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OpenCloudOS-Kernel/drivers/spi/spi.c

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/*
* SPI init/core code
*
* Copyright (C) 2005 David Brownell
* Copyright (C) 2008 Secret Lab Technologies Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/cache.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/mutex.h>
#include <linux/of_device.h>
#include <linux/of_irq.h>
#include <linux/clk/clk-conf.h>
#include <linux/slab.h>
#include <linux/mod_devicetable.h>
#include <linux/spi/spi.h>
#include <linux/of_gpio.h>
#include <linux/pm_runtime.h>
#include <linux/pm_domain.h>
#include <linux/export.h>
#include <linux/sched/rt.h>
#include <linux/delay.h>
#include <linux/kthread.h>
#include <linux/ioport.h>
#include <linux/acpi.h>
#define CREATE_TRACE_POINTS
#include <trace/events/spi.h>
static void spidev_release(struct device *dev)
{
struct spi_device *spi = to_spi_device(dev);
/* spi masters may cleanup for released devices */
if (spi->master->cleanup)
spi->master->cleanup(spi);
spi_master_put(spi->master);
kfree(spi);
}
static ssize_t
modalias_show(struct device *dev, struct device_attribute *a, char *buf)
{
const struct spi_device *spi = to_spi_device(dev);
int len;
len = acpi_device_modalias(dev, buf, PAGE_SIZE - 1);
if (len != -ENODEV)
return len;
return sprintf(buf, "%s%s\n", SPI_MODULE_PREFIX, spi->modalias);
}
static DEVICE_ATTR_RO(modalias);
#define SPI_STATISTICS_ATTRS(field, file) \
static ssize_t spi_master_##field##_show(struct device *dev, \
struct device_attribute *attr, \
char *buf) \
{ \
struct spi_master *master = container_of(dev, \
struct spi_master, dev); \
return spi_statistics_##field##_show(&master->statistics, buf); \
} \
static struct device_attribute dev_attr_spi_master_##field = { \
.attr = { .name = file, .mode = S_IRUGO }, \
.show = spi_master_##field##_show, \
}; \
static ssize_t spi_device_##field##_show(struct device *dev, \
struct device_attribute *attr, \
char *buf) \
{ \
struct spi_device *spi = container_of(dev, \
struct spi_device, dev); \
return spi_statistics_##field##_show(&spi->statistics, buf); \
} \
static struct device_attribute dev_attr_spi_device_##field = { \
.attr = { .name = file, .mode = S_IRUGO }, \
.show = spi_device_##field##_show, \
}
#define SPI_STATISTICS_SHOW_NAME(name, file, field, format_string) \
static ssize_t spi_statistics_##name##_show(struct spi_statistics *stat, \
char *buf) \
{ \
unsigned long flags; \
ssize_t len; \
spin_lock_irqsave(&stat->lock, flags); \
len = sprintf(buf, format_string, stat->field); \
spin_unlock_irqrestore(&stat->lock, flags); \
return len; \
} \
SPI_STATISTICS_ATTRS(name, file)
#define SPI_STATISTICS_SHOW(field, format_string) \
SPI_STATISTICS_SHOW_NAME(field, __stringify(field), \
field, format_string)
SPI_STATISTICS_SHOW(messages, "%lu");
SPI_STATISTICS_SHOW(transfers, "%lu");
SPI_STATISTICS_SHOW(errors, "%lu");
SPI_STATISTICS_SHOW(timedout, "%lu");
SPI_STATISTICS_SHOW(spi_sync, "%lu");
SPI_STATISTICS_SHOW(spi_sync_immediate, "%lu");
SPI_STATISTICS_SHOW(spi_async, "%lu");
SPI_STATISTICS_SHOW(bytes, "%llu");
SPI_STATISTICS_SHOW(bytes_rx, "%llu");
SPI_STATISTICS_SHOW(bytes_tx, "%llu");
static struct attribute *spi_dev_attrs[] = {
&dev_attr_modalias.attr,
NULL,
};
static const struct attribute_group spi_dev_group = {
.attrs = spi_dev_attrs,
};
static struct attribute *spi_device_statistics_attrs[] = {
&dev_attr_spi_device_messages.attr,
&dev_attr_spi_device_transfers.attr,
&dev_attr_spi_device_errors.attr,
&dev_attr_spi_device_timedout.attr,
&dev_attr_spi_device_spi_sync.attr,
&dev_attr_spi_device_spi_sync_immediate.attr,
&dev_attr_spi_device_spi_async.attr,
&dev_attr_spi_device_bytes.attr,
&dev_attr_spi_device_bytes_rx.attr,
&dev_attr_spi_device_bytes_tx.attr,
NULL,
};
static const struct attribute_group spi_device_statistics_group = {
.name = "statistics",
.attrs = spi_device_statistics_attrs,
};
static const struct attribute_group *spi_dev_groups[] = {
&spi_dev_group,
&spi_device_statistics_group,
NULL,
};
static struct attribute *spi_master_statistics_attrs[] = {
&dev_attr_spi_master_messages.attr,
&dev_attr_spi_master_transfers.attr,
&dev_attr_spi_master_errors.attr,
&dev_attr_spi_master_timedout.attr,
&dev_attr_spi_master_spi_sync.attr,
&dev_attr_spi_master_spi_sync_immediate.attr,
&dev_attr_spi_master_spi_async.attr,
&dev_attr_spi_master_bytes.attr,
&dev_attr_spi_master_bytes_rx.attr,
&dev_attr_spi_master_bytes_tx.attr,
NULL,
};
static const struct attribute_group spi_master_statistics_group = {
.name = "statistics",
.attrs = spi_master_statistics_attrs,
};
static const struct attribute_group *spi_master_groups[] = {
&spi_master_statistics_group,
NULL,
};
void spi_statistics_add_transfer_stats(struct spi_statistics *stats,
struct spi_transfer *xfer,
struct spi_master *master)
{
unsigned long flags;
spin_lock_irqsave(&stats->lock, flags);
stats->transfers++;
stats->bytes += xfer->len;
if ((xfer->tx_buf) &&
(xfer->tx_buf != master->dummy_tx))
stats->bytes_tx += xfer->len;
if ((xfer->rx_buf) &&
(xfer->rx_buf != master->dummy_rx))
stats->bytes_rx += xfer->len;
spin_unlock_irqrestore(&stats->lock, flags);
}
EXPORT_SYMBOL_GPL(spi_statistics_add_transfer_stats);
/* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
* and the sysfs version makes coldplug work too.
*/
static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
const struct spi_device *sdev)
{
while (id->name[0]) {
if (!strcmp(sdev->modalias, id->name))
return id;
id++;
}
return NULL;
}
const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
{
const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
return spi_match_id(sdrv->id_table, sdev);
}
EXPORT_SYMBOL_GPL(spi_get_device_id);
static int spi_match_device(struct device *dev, struct device_driver *drv)
{
const struct spi_device *spi = to_spi_device(dev);
const struct spi_driver *sdrv = to_spi_driver(drv);
/* Attempt an OF style match */
if (of_driver_match_device(dev, drv))
return 1;
/* Then try ACPI */
if (acpi_driver_match_device(dev, drv))
return 1;
if (sdrv->id_table)
return !!spi_match_id(sdrv->id_table, spi);
return strcmp(spi->modalias, drv->name) == 0;
}
static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
{
const struct spi_device *spi = to_spi_device(dev);
int rc;
rc = acpi_device_uevent_modalias(dev, env);
if (rc != -ENODEV)
return rc;
add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
return 0;
}
struct bus_type spi_bus_type = {
.name = "spi",
.dev_groups = spi_dev_groups,
.match = spi_match_device,
.uevent = spi_uevent,
};
EXPORT_SYMBOL_GPL(spi_bus_type);
static int spi_drv_probe(struct device *dev)
{
const struct spi_driver *sdrv = to_spi_driver(dev->driver);
int ret;
ret = of_clk_set_defaults(dev->of_node, false);
if (ret)
return ret;
ret = dev_pm_domain_attach(dev, true);
if (ret != -EPROBE_DEFER) {
ret = sdrv->probe(to_spi_device(dev));
if (ret)
dev_pm_domain_detach(dev, true);
}
return ret;
}
static int spi_drv_remove(struct device *dev)
{
const struct spi_driver *sdrv = to_spi_driver(dev->driver);
int ret;
ret = sdrv->remove(to_spi_device(dev));
dev_pm_domain_detach(dev, true);
return ret;
}
static void spi_drv_shutdown(struct device *dev)
{
const struct spi_driver *sdrv = to_spi_driver(dev->driver);
sdrv->shutdown(to_spi_device(dev));
}
/**
* spi_register_driver - register a SPI driver
* @sdrv: the driver to register
* Context: can sleep
*/
int spi_register_driver(struct spi_driver *sdrv)
{
sdrv->driver.bus = &spi_bus_type;
if (sdrv->probe)
sdrv->driver.probe = spi_drv_probe;
if (sdrv->remove)
sdrv->driver.remove = spi_drv_remove;
if (sdrv->shutdown)
sdrv->driver.shutdown = spi_drv_shutdown;
return driver_register(&sdrv->driver);
}
EXPORT_SYMBOL_GPL(spi_register_driver);
/*-------------------------------------------------------------------------*/
/* SPI devices should normally not be created by SPI device drivers; that
* would make them board-specific. Similarly with SPI master drivers.
* Device registration normally goes into like arch/.../mach.../board-YYY.c
* with other readonly (flashable) information about mainboard devices.
*/
struct boardinfo {
struct list_head list;
struct spi_board_info board_info;
};
static LIST_HEAD(board_list);
static LIST_HEAD(spi_master_list);
/*
* Used to protect add/del opertion for board_info list and
* spi_master list, and their matching process
*/
static DEFINE_MUTEX(board_lock);
/**
* spi_alloc_device - Allocate a new SPI device
* @master: Controller to which device is connected
* Context: can sleep
*
* Allows a driver to allocate and initialize a spi_device without
* registering it immediately. This allows a driver to directly
* fill the spi_device with device parameters before calling
* spi_add_device() on it.
*
* Caller is responsible to call spi_add_device() on the returned
* spi_device structure to add it to the SPI master. If the caller
* needs to discard the spi_device without adding it, then it should
* call spi_dev_put() on it.
*
* Returns a pointer to the new device, or NULL.
*/
struct spi_device *spi_alloc_device(struct spi_master *master)
{
struct spi_device *spi;
if (!spi_master_get(master))
return NULL;
spi = kzalloc(sizeof(*spi), GFP_KERNEL);
if (!spi) {
spi_master_put(master);
return NULL;
}
spi->master = master;
spi->dev.parent = &master->dev;
spi->dev.bus = &spi_bus_type;
spi->dev.release = spidev_release;
spi->cs_gpio = -ENOENT;
spin_lock_init(&spi->statistics.lock);
device_initialize(&spi->dev);
return spi;
}
EXPORT_SYMBOL_GPL(spi_alloc_device);
static void spi_dev_set_name(struct spi_device *spi)
{
struct acpi_device *adev = ACPI_COMPANION(&spi->dev);
if (adev) {
dev_set_name(&spi->dev, "spi-%s", acpi_dev_name(adev));
return;
}
dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->master->dev),
spi->chip_select);
}
static int spi_dev_check(struct device *dev, void *data)
{
struct spi_device *spi = to_spi_device(dev);
struct spi_device *new_spi = data;
if (spi->master == new_spi->master &&
spi->chip_select == new_spi->chip_select)
return -EBUSY;
return 0;
}
/**
* spi_add_device - Add spi_device allocated with spi_alloc_device
* @spi: spi_device to register
*
* Companion function to spi_alloc_device. Devices allocated with
* spi_alloc_device can be added onto the spi bus with this function.
*
* Returns 0 on success; negative errno on failure
*/
int spi_add_device(struct spi_device *spi)
{
static DEFINE_MUTEX(spi_add_lock);
struct spi_master *master = spi->master;
struct device *dev = master->dev.parent;
int status;
/* Chipselects are numbered 0..max; validate. */
if (spi->chip_select >= master->num_chipselect) {
dev_err(dev, "cs%d >= max %d\n",
spi->chip_select,
master->num_chipselect);
return -EINVAL;
}
/* Set the bus ID string */
spi_dev_set_name(spi);
/* We need to make sure there's no other device with this
* chipselect **BEFORE** we call setup(), else we'll trash
* its configuration. Lock against concurrent add() calls.
*/
mutex_lock(&spi_add_lock);
status = bus_for_each_dev(&spi_bus_type, NULL, spi, spi_dev_check);
if (status) {
dev_err(dev, "chipselect %d already in use\n",
spi->chip_select);
goto done;
}
if (master->cs_gpios)
spi->cs_gpio = master->cs_gpios[spi->chip_select];
/* Drivers may modify this initial i/o setup, but will
* normally rely on the device being setup. Devices
* using SPI_CS_HIGH can't coexist well otherwise...
*/
status = spi_setup(spi);
if (status < 0) {
dev_err(dev, "can't setup %s, status %d\n",
dev_name(&spi->dev), status);
goto done;
}
/* Device may be bound to an active driver when this returns */
status = device_add(&spi->dev);
if (status < 0)
dev_err(dev, "can't add %s, status %d\n",
dev_name(&spi->dev), status);
else
dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
done:
mutex_unlock(&spi_add_lock);
return status;
}
EXPORT_SYMBOL_GPL(spi_add_device);
/**
* spi_new_device - instantiate one new SPI device
* @master: Controller to which device is connected
* @chip: Describes the SPI device
* Context: can sleep
*
* On typical mainboards, this is purely internal; and it's not needed
* after board init creates the hard-wired devices. Some development
* platforms may not be able to use spi_register_board_info though, and
* this is exported so that for example a USB or parport based adapter
* driver could add devices (which it would learn about out-of-band).
*
* Returns the new device, or NULL.
*/
struct spi_device *spi_new_device(struct spi_master *master,
struct spi_board_info *chip)
{
struct spi_device *proxy;
int status;
/* NOTE: caller did any chip->bus_num checks necessary.
*
* Also, unless we change the return value convention to use
* error-or-pointer (not NULL-or-pointer), troubleshootability
* suggests syslogged diagnostics are best here (ugh).
*/
proxy = spi_alloc_device(master);
if (!proxy)
return NULL;
WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
proxy->chip_select = chip->chip_select;
proxy->max_speed_hz = chip->max_speed_hz;
proxy->mode = chip->mode;
proxy->irq = chip->irq;
strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
proxy->dev.platform_data = (void *) chip->platform_data;
proxy->controller_data = chip->controller_data;
proxy->controller_state = NULL;
status = spi_add_device(proxy);
if (status < 0) {
spi_dev_put(proxy);
return NULL;
}
return proxy;
}
EXPORT_SYMBOL_GPL(spi_new_device);
static void spi_match_master_to_boardinfo(struct spi_master *master,
struct spi_board_info *bi)
{
struct spi_device *dev;
if (master->bus_num != bi->bus_num)
return;
dev = spi_new_device(master, bi);
if (!dev)
dev_err(master->dev.parent, "can't create new device for %s\n",
bi->modalias);
}
/**
* spi_register_board_info - register SPI devices for a given board
* @info: array of chip descriptors
* @n: how many descriptors are provided
* Context: can sleep
*
* Board-specific early init code calls this (probably during arch_initcall)
* with segments of the SPI device table. Any device nodes are created later,
* after the relevant parent SPI controller (bus_num) is defined. We keep
* this table of devices forever, so that reloading a controller driver will
* not make Linux forget about these hard-wired devices.
*
* Other code can also call this, e.g. a particular add-on board might provide
* SPI devices through its expansion connector, so code initializing that board
* would naturally declare its SPI devices.
*
* The board info passed can safely be __initdata ... but be careful of
* any embedded pointers (platform_data, etc), they're copied as-is.
*/
int spi_register_board_info(struct spi_board_info const *info, unsigned n)
{
struct boardinfo *bi;
int i;
if (!n)
return -EINVAL;
bi = kzalloc(n * sizeof(*bi), GFP_KERNEL);
if (!bi)
return -ENOMEM;
for (i = 0; i < n; i++, bi++, info++) {
struct spi_master *master;
memcpy(&bi->board_info, info, sizeof(*info));
mutex_lock(&board_lock);
list_add_tail(&bi->list, &board_list);
list_for_each_entry(master, &spi_master_list, list)
spi_match_master_to_boardinfo(master, &bi->board_info);
mutex_unlock(&board_lock);
}
return 0;
}
/*-------------------------------------------------------------------------*/
static void spi_set_cs(struct spi_device *spi, bool enable)
{
if (spi->mode & SPI_CS_HIGH)
enable = !enable;
if (spi->cs_gpio >= 0)
gpio_set_value(spi->cs_gpio, !enable);
else if (spi->master->set_cs)
spi->master->set_cs(spi, !enable);
}
#ifdef CONFIG_HAS_DMA
static int spi_map_buf(struct spi_master *master, struct device *dev,
struct sg_table *sgt, void *buf, size_t len,
enum dma_data_direction dir)
{
const bool vmalloced_buf = is_vmalloc_addr(buf);
int desc_len;
int sgs;
struct page *vm_page;
void *sg_buf;
size_t min;
int i, ret;
if (vmalloced_buf) {
desc_len = PAGE_SIZE;
sgs = DIV_ROUND_UP(len + offset_in_page(buf), desc_len);
} else {
desc_len = master->max_dma_len;
sgs = DIV_ROUND_UP(len, desc_len);
}
ret = sg_alloc_table(sgt, sgs, GFP_KERNEL);
if (ret != 0)
return ret;
for (i = 0; i < sgs; i++) {
if (vmalloced_buf) {
min = min_t(size_t,
len, desc_len - offset_in_page(buf));
vm_page = vmalloc_to_page(buf);
if (!vm_page) {
sg_free_table(sgt);
return -ENOMEM;
}
sg_set_page(&sgt->sgl[i], vm_page,
min, offset_in_page(buf));
} else {
min = min_t(size_t, len, desc_len);
sg_buf = buf;
sg_set_buf(&sgt->sgl[i], sg_buf, min);
}
buf += min;
len -= min;
}
ret = dma_map_sg(dev, sgt->sgl, sgt->nents, dir);
if (!ret)
ret = -ENOMEM;
if (ret < 0) {
sg_free_table(sgt);
return ret;
}
sgt->nents = ret;
return 0;
}
static void spi_unmap_buf(struct spi_master *master, struct device *dev,
struct sg_table *sgt, enum dma_data_direction dir)
{
if (sgt->orig_nents) {
dma_unmap_sg(dev, sgt->sgl, sgt->orig_nents, dir);
sg_free_table(sgt);
}
}
static int __spi_map_msg(struct spi_master *master, struct spi_message *msg)
{
struct device *tx_dev, *rx_dev;
struct spi_transfer *xfer;
int ret;
if (!master->can_dma)
return 0;
if (master->dma_tx)
tx_dev = master->dma_tx->device->dev;
else
tx_dev = &master->dev;
if (master->dma_rx)
rx_dev = master->dma_rx->device->dev;
else
rx_dev = &master->dev;
list_for_each_entry(xfer, &msg->transfers, transfer_list) {
if (!master->can_dma(master, msg->spi, xfer))
continue;
if (xfer->tx_buf != NULL) {
ret = spi_map_buf(master, tx_dev, &xfer->tx_sg,
(void *)xfer->tx_buf, xfer->len,
DMA_TO_DEVICE);
if (ret != 0)
return ret;
}
if (xfer->rx_buf != NULL) {
ret = spi_map_buf(master, rx_dev, &xfer->rx_sg,
xfer->rx_buf, xfer->len,
DMA_FROM_DEVICE);
if (ret != 0) {
spi_unmap_buf(master, tx_dev, &xfer->tx_sg,
DMA_TO_DEVICE);
return ret;
}
}
}
master->cur_msg_mapped = true;
return 0;
}
static int __spi_unmap_msg(struct spi_master *master, struct spi_message *msg)
{
struct spi_transfer *xfer;
struct device *tx_dev, *rx_dev;
if (!master->cur_msg_mapped || !master->can_dma)
return 0;
if (master->dma_tx)
tx_dev = master->dma_tx->device->dev;
else
tx_dev = &master->dev;
if (master->dma_rx)
rx_dev = master->dma_rx->device->dev;
else
rx_dev = &master->dev;
list_for_each_entry(xfer, &msg->transfers, transfer_list) {
if (!master->can_dma(master, msg->spi, xfer))
continue;
spi_unmap_buf(master, rx_dev, &xfer->rx_sg, DMA_FROM_DEVICE);
spi_unmap_buf(master, tx_dev, &xfer->tx_sg, DMA_TO_DEVICE);
}
return 0;
}
#else /* !CONFIG_HAS_DMA */
static inline int __spi_map_msg(struct spi_master *master,
struct spi_message *msg)
{
return 0;
}
static inline int __spi_unmap_msg(struct spi_master *master,
struct spi_message *msg)
{
return 0;
}
#endif /* !CONFIG_HAS_DMA */
static inline int spi_unmap_msg(struct spi_master *master,
struct spi_message *msg)
{
struct spi_transfer *xfer;
list_for_each_entry(xfer, &msg->transfers, transfer_list) {
/*
* Restore the original value of tx_buf or rx_buf if they are
* NULL.
*/
if (xfer->tx_buf == master->dummy_tx)
xfer->tx_buf = NULL;
if (xfer->rx_buf == master->dummy_rx)
xfer->rx_buf = NULL;
}
return __spi_unmap_msg(master, msg);
}
static int spi_map_msg(struct spi_master *master, struct spi_message *msg)
{
struct spi_transfer *xfer;
void *tmp;
unsigned int max_tx, max_rx;
if (master->flags & (SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX)) {
max_tx = 0;
max_rx = 0;
list_for_each_entry(xfer, &msg->transfers, transfer_list) {
if ((master->flags & SPI_MASTER_MUST_TX) &&
!xfer->tx_buf)
max_tx = max(xfer->len, max_tx);
if ((master->flags & SPI_MASTER_MUST_RX) &&
!xfer->rx_buf)
max_rx = max(xfer->len, max_rx);
}
if (max_tx) {
tmp = krealloc(master->dummy_tx, max_tx,
GFP_KERNEL | GFP_DMA);
if (!tmp)
return -ENOMEM;
master->dummy_tx = tmp;
memset(tmp, 0, max_tx);
}
if (max_rx) {
tmp = krealloc(master->dummy_rx, max_rx,
GFP_KERNEL | GFP_DMA);
if (!tmp)
return -ENOMEM;
master->dummy_rx = tmp;
}
if (max_tx || max_rx) {
list_for_each_entry(xfer, &msg->transfers,
transfer_list) {
if (!xfer->tx_buf)
xfer->tx_buf = master->dummy_tx;
if (!xfer->rx_buf)
xfer->rx_buf = master->dummy_rx;
}
}
}
return __spi_map_msg(master, msg);
}
/*
* spi_transfer_one_message - Default implementation of transfer_one_message()
*
* This is a standard implementation of transfer_one_message() for
* drivers which impelment a transfer_one() operation. It provides
* standard handling of delays and chip select management.
*/
static int spi_transfer_one_message(struct spi_master *master,
struct spi_message *msg)
{
struct spi_transfer *xfer;
bool keep_cs = false;
int ret = 0;
unsigned long ms = 1;
struct spi_statistics *statm = &master->statistics;
struct spi_statistics *stats = &msg->spi->statistics;
spi_set_cs(msg->spi, true);
SPI_STATISTICS_INCREMENT_FIELD(statm, messages);
SPI_STATISTICS_INCREMENT_FIELD(stats, messages);
list_for_each_entry(xfer, &msg->transfers, transfer_list) {
trace_spi_transfer_start(msg, xfer);
spi_statistics_add_transfer_stats(statm, xfer, master);
spi_statistics_add_transfer_stats(stats, xfer, master);
if (xfer->tx_buf || xfer->rx_buf) {
reinit_completion(&master->xfer_completion);
ret = master->transfer_one(master, msg->spi, xfer);
if (ret < 0) {
SPI_STATISTICS_INCREMENT_FIELD(statm,
errors);
SPI_STATISTICS_INCREMENT_FIELD(stats,
errors);
dev_err(&msg->spi->dev,
"SPI transfer failed: %d\n", ret);
goto out;
}
if (ret > 0) {
ret = 0;
ms = xfer->len * 8 * 1000 / xfer->speed_hz;
ms += ms + 100; /* some tolerance */
ms = wait_for_completion_timeout(&master->xfer_completion,
msecs_to_jiffies(ms));
}
if (ms == 0) {
SPI_STATISTICS_INCREMENT_FIELD(statm,
timedout);
SPI_STATISTICS_INCREMENT_FIELD(stats,
timedout);
dev_err(&msg->spi->dev,
"SPI transfer timed out\n");
msg->status = -ETIMEDOUT;
}
} else {
if (xfer->len)
dev_err(&msg->spi->dev,
"Bufferless transfer has length %u\n",
xfer->len);
}
trace_spi_transfer_stop(msg, xfer);
if (msg->status != -EINPROGRESS)
goto out;
if (xfer->delay_usecs)
udelay(xfer->delay_usecs);
if (xfer->cs_change) {
if (list_is_last(&xfer->transfer_list,
&msg->transfers)) {
keep_cs = true;
} else {
spi_set_cs(msg->spi, false);
udelay(10);
spi_set_cs(msg->spi, true);
}
}
msg->actual_length += xfer->len;
}
out:
if (ret != 0 || !keep_cs)
spi_set_cs(msg->spi, false);
if (msg->status == -EINPROGRESS)
msg->status = ret;
if (msg->status && master->handle_err)
master->handle_err(master, msg);
spi_finalize_current_message(master);
return ret;
}
/**
* spi_finalize_current_transfer - report completion of a transfer
* @master: the master reporting completion
*
* Called by SPI drivers using the core transfer_one_message()
* implementation to notify it that the current interrupt driven
* transfer has finished and the next one may be scheduled.
*/
void spi_finalize_current_transfer(struct spi_master *master)
{
complete(&master->xfer_completion);
}
EXPORT_SYMBOL_GPL(spi_finalize_current_transfer);
/**
* __spi_pump_messages - function which processes spi message queue
* @master: master to process queue for
* @in_kthread: true if we are in the context of the message pump thread
*
* This function checks if there is any spi message in the queue that
* needs processing and if so call out to the driver to initialize hardware
* and transfer each message.
*
* Note that it is called both from the kthread itself and also from
* inside spi_sync(); the queue extraction handling at the top of the
* function should deal with this safely.
*/
static void __spi_pump_messages(struct spi_master *master, bool in_kthread)
{
unsigned long flags;
bool was_busy = false;
int ret;
/* Lock queue */
spin_lock_irqsave(&master->queue_lock, flags);
/* Make sure we are not already running a message */
if (master->cur_msg) {
spin_unlock_irqrestore(&master->queue_lock, flags);
return;
}
/* If another context is idling the device then defer */
if (master->idling) {
queue_kthread_work(&master->kworker, &master->pump_messages);
spin_unlock_irqrestore(&master->queue_lock, flags);
return;
}
/* Check if the queue is idle */
if (list_empty(&master->queue) || !master->running) {
if (!master->busy) {
spin_unlock_irqrestore(&master->queue_lock, flags);
return;
}
/* Only do teardown in the thread */
if (!in_kthread) {
queue_kthread_work(&master->kworker,
&master->pump_messages);
spin_unlock_irqrestore(&master->queue_lock, flags);
return;
}
master->busy = false;
master->idling = true;
spin_unlock_irqrestore(&master->queue_lock, flags);
kfree(master->dummy_rx);
master->dummy_rx = NULL;
kfree(master->dummy_tx);
master->dummy_tx = NULL;
if (master->unprepare_transfer_hardware &&
master->unprepare_transfer_hardware(master))
dev_err(&master->dev,
"failed to unprepare transfer hardware\n");
if (master->auto_runtime_pm) {
pm_runtime_mark_last_busy(master->dev.parent);
pm_runtime_put_autosuspend(master->dev.parent);
}
trace_spi_master_idle(master);
spin_lock_irqsave(&master->queue_lock, flags);
master->idling = false;
spin_unlock_irqrestore(&master->queue_lock, flags);
return;
}
/* Extract head of queue */
master->cur_msg =
list_first_entry(&master->queue, struct spi_message, queue);
list_del_init(&master->cur_msg->queue);
if (master->busy)
was_busy = true;
else
master->busy = true;
spin_unlock_irqrestore(&master->queue_lock, flags);
if (!was_busy && master->auto_runtime_pm) {
ret = pm_runtime_get_sync(master->dev.parent);
if (ret < 0) {
dev_err(&master->dev, "Failed to power device: %d\n",
ret);
return;
}
}
if (!was_busy)
trace_spi_master_busy(master);
if (!was_busy && master->prepare_transfer_hardware) {
ret = master->prepare_transfer_hardware(master);
if (ret) {
dev_err(&master->dev,
"failed to prepare transfer hardware\n");
if (master->auto_runtime_pm)
pm_runtime_put(master->dev.parent);
return;
}
}
trace_spi_message_start(master->cur_msg);
if (master->prepare_message) {
ret = master->prepare_message(master, master->cur_msg);
if (ret) {
dev_err(&master->dev,
"failed to prepare message: %d\n", ret);
master->cur_msg->status = ret;
spi_finalize_current_message(master);
return;
}
master->cur_msg_prepared = true;
}
ret = spi_map_msg(master, master->cur_msg);
if (ret) {
master->cur_msg->status = ret;
spi_finalize_current_message(master);
return;
}
ret = master->transfer_one_message(master, master->cur_msg);
if (ret) {
dev_err(&master->dev,
"failed to transfer one message from queue\n");
return;
}
}
/**
* spi_pump_messages - kthread work function which processes spi message queue
* @work: pointer to kthread work struct contained in the master struct
*/
static void spi_pump_messages(struct kthread_work *work)
{
struct spi_master *master =
container_of(work, struct spi_master, pump_messages);
__spi_pump_messages(master, true);
}
static int spi_init_queue(struct spi_master *master)
{
struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
master->running = false;
master->busy = false;
init_kthread_worker(&master->kworker);
master->kworker_task = kthread_run(kthread_worker_fn,
&master->kworker, "%s",
dev_name(&master->dev));
if (IS_ERR(master->kworker_task)) {
dev_err(&master->dev, "failed to create message pump task\n");
return PTR_ERR(master->kworker_task);
}
init_kthread_work(&master->pump_messages, spi_pump_messages);
/*
* Master config will indicate if this controller should run the
* message pump with high (realtime) priority to reduce the transfer
* latency on the bus by minimising the delay between a transfer
* request and the scheduling of the message pump thread. Without this
* setting the message pump thread will remain at default priority.
*/
if (master->rt) {
dev_info(&master->dev,
"will run message pump with realtime priority\n");
sched_setscheduler(master->kworker_task, SCHED_FIFO, &param);
}
return 0;
}
/**
* spi_get_next_queued_message() - called by driver to check for queued
* messages
* @master: the master to check for queued messages
*
* If there are more messages in the queue, the next message is returned from
* this call.
*/
struct spi_message *spi_get_next_queued_message(struct spi_master *master)
{
struct spi_message *next;
unsigned long flags;
/* get a pointer to the next message, if any */
spin_lock_irqsave(&master->queue_lock, flags);
next = list_first_entry_or_null(&master->queue, struct spi_message,
queue);
spin_unlock_irqrestore(&master->queue_lock, flags);
return next;
}
EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
/**
* spi_finalize_current_message() - the current message is complete
* @master: the master to return the message to
*
* Called by the driver to notify the core that the message in the front of the
* queue is complete and can be removed from the queue.
*/
void spi_finalize_current_message(struct spi_master *master)
{
struct spi_message *mesg;
unsigned long flags;
int ret;
spin_lock_irqsave(&master->queue_lock, flags);
mesg = master->cur_msg;
spin_unlock_irqrestore(&master->queue_lock, flags);
spi_unmap_msg(master, mesg);
if (master->cur_msg_prepared && master->unprepare_message) {
ret = master->unprepare_message(master, mesg);
if (ret) {
dev_err(&master->dev,
"failed to unprepare message: %d\n", ret);
}
}
spin_lock_irqsave(&master->queue_lock, flags);
master->cur_msg = NULL;
master->cur_msg_prepared = false;
queue_kthread_work(&master->kworker, &master->pump_messages);
spin_unlock_irqrestore(&master->queue_lock, flags);
trace_spi_message_done(mesg);
mesg->state = NULL;
if (mesg->complete)
mesg->complete(mesg->context);
}
EXPORT_SYMBOL_GPL(spi_finalize_current_message);
static int spi_start_queue(struct spi_master *master)
{
unsigned long flags;
spin_lock_irqsave(&master->queue_lock, flags);
if (master->running || master->busy) {
spin_unlock_irqrestore(&master->queue_lock, flags);
return -EBUSY;
}
master->running = true;
master->cur_msg = NULL;
spin_unlock_irqrestore(&master->queue_lock, flags);
queue_kthread_work(&master->kworker, &master->pump_messages);
return 0;
}
static int spi_stop_queue(struct spi_master *master)
{
unsigned long flags;
unsigned limit = 500;
int ret = 0;
spin_lock_irqsave(&master->queue_lock, flags);
/*
* This is a bit lame, but is optimized for the common execution path.
* A wait_queue on the master->busy could be used, but then the common
* execution path (pump_messages) would be required to call wake_up or
* friends on every SPI message. Do this instead.
*/
while ((!list_empty(&master->queue) || master->busy) && limit--) {
spin_unlock_irqrestore(&master->queue_lock, flags);
usleep_range(10000, 11000);
spin_lock_irqsave(&master->queue_lock, flags);
}
if (!list_empty(&master->queue) || master->busy)
ret = -EBUSY;
else
master->running = false;
spin_unlock_irqrestore(&master->queue_lock, flags);
if (ret) {
dev_warn(&master->dev,
"could not stop message queue\n");
return ret;
}
return ret;
}
static int spi_destroy_queue(struct spi_master *master)
{
int ret;
ret = spi_stop_queue(master);
/*
* flush_kthread_worker will block until all work is done.
* If the reason that stop_queue timed out is that the work will never
* finish, then it does no good to call flush/stop thread, so
* return anyway.
*/
if (ret) {
dev_err(&master->dev, "problem destroying queue\n");
return ret;
}
flush_kthread_worker(&master->kworker);
kthread_stop(master->kworker_task);
return 0;
}
static int __spi_queued_transfer(struct spi_device *spi,
struct spi_message *msg,
bool need_pump)
{
struct spi_master *master = spi->master;
unsigned long flags;
spin_lock_irqsave(&master->queue_lock, flags);
if (!master->running) {
spin_unlock_irqrestore(&master->queue_lock, flags);
return -ESHUTDOWN;
}
msg->actual_length = 0;
msg->status = -EINPROGRESS;
list_add_tail(&msg->queue, &master->queue);
if (!master->busy && need_pump)
queue_kthread_work(&master->kworker, &master->pump_messages);
spin_unlock_irqrestore(&master->queue_lock, flags);
return 0;
}
/**
* spi_queued_transfer - transfer function for queued transfers
* @spi: spi device which is requesting transfer
* @msg: spi message which is to handled is queued to driver queue
*/
static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
{
return __spi_queued_transfer(spi, msg, true);
}
static int spi_master_initialize_queue(struct spi_master *master)
{
int ret;
master->transfer = spi_queued_transfer;
if (!master->transfer_one_message)
master->transfer_one_message = spi_transfer_one_message;
/* Initialize and start queue */
ret = spi_init_queue(master);
if (ret) {
dev_err(&master->dev, "problem initializing queue\n");
goto err_init_queue;
}
master->queued = true;
ret = spi_start_queue(master);
if (ret) {
dev_err(&master->dev, "problem starting queue\n");
goto err_start_queue;
}
return 0;
err_start_queue:
spi_destroy_queue(master);
err_init_queue:
return ret;
}
/*-------------------------------------------------------------------------*/
#if defined(CONFIG_OF)
static struct spi_device *
of_register_spi_device(struct spi_master *master, struct device_node *nc)
{
struct spi_device *spi;
int rc;
u32 value;
/* Alloc an spi_device */
spi = spi_alloc_device(master);
if (!spi) {
dev_err(&master->dev, "spi_device alloc error for %s\n",
nc->full_name);
rc = -ENOMEM;
goto err_out;
}
/* Select device driver */
rc = of_modalias_node(nc, spi->modalias,
sizeof(spi->modalias));
if (rc < 0) {
dev_err(&master->dev, "cannot find modalias for %s\n",
nc->full_name);
goto err_out;
}
/* Device address */
rc = of_property_read_u32(nc, "reg", &value);
if (rc) {
dev_err(&master->dev, "%s has no valid 'reg' property (%d)\n",
nc->full_name, rc);
goto err_out;
}
spi->chip_select = value;
/* Mode (clock phase/polarity/etc.) */
if (of_find_property(nc, "spi-cpha", NULL))
spi->mode |= SPI_CPHA;
if (of_find_property(nc, "spi-cpol", NULL))
spi->mode |= SPI_CPOL;
if (of_find_property(nc, "spi-cs-high", NULL))
spi->mode |= SPI_CS_HIGH;
if (of_find_property(nc, "spi-3wire", NULL))
spi->mode |= SPI_3WIRE;
if (of_find_property(nc, "spi-lsb-first", NULL))
spi->mode |= SPI_LSB_FIRST;
/* Device DUAL/QUAD mode */
if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {
switch (value) {
case 1:
break;
case 2:
spi->mode |= SPI_TX_DUAL;
break;
case 4:
spi->mode |= SPI_TX_QUAD;
break;
default:
dev_warn(&master->dev,
"spi-tx-bus-width %d not supported\n",
value);
break;
}
}
if (!of_property_read_u32(nc, "spi-rx-bus-width", &value)) {
switch (value) {
case 1:
break;
case 2:
spi->mode |= SPI_RX_DUAL;
break;
case 4:
spi->mode |= SPI_RX_QUAD;
break;
default:
dev_warn(&master->dev,
"spi-rx-bus-width %d not supported\n",
value);
break;
}
}
/* Device speed */
rc = of_property_read_u32(nc, "spi-max-frequency", &value);
if (rc) {
dev_err(&master->dev, "%s has no valid 'spi-max-frequency' property (%d)\n",
nc->full_name, rc);
goto err_out;
}
spi->max_speed_hz = value;
/* IRQ */
spi->irq = irq_of_parse_and_map(nc, 0);
/* Store a pointer to the node in the device structure */
of_node_get(nc);
spi->dev.of_node = nc;
/* Register the new device */
rc = spi_add_device(spi);
if (rc) {
dev_err(&master->dev, "spi_device register error %s\n",
nc->full_name);
goto err_out;
}
return spi;
err_out:
spi_dev_put(spi);
return ERR_PTR(rc);
}
/**
* of_register_spi_devices() - Register child devices onto the SPI bus
* @master: Pointer to spi_master device
*
* Registers an spi_device for each child node of master node which has a 'reg'
* property.
*/
static void of_register_spi_devices(struct spi_master *master)
{
struct spi_device *spi;
struct device_node *nc;
if (!master->dev.of_node)
return;
for_each_available_child_of_node(master->dev.of_node, nc) {
spi = of_register_spi_device(master, nc);
if (IS_ERR(spi))
dev_warn(&master->dev, "Failed to create SPI device for %s\n",
nc->full_name);
}
}
#else
static void of_register_spi_devices(struct spi_master *master) { }
#endif
#ifdef CONFIG_ACPI
static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
{
struct spi_device *spi = data;
if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
struct acpi_resource_spi_serialbus *sb;
sb = &ares->data.spi_serial_bus;
if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_SPI) {
spi->chip_select = sb->device_selection;
spi->max_speed_hz = sb->connection_speed;
if (sb->clock_phase == ACPI_SPI_SECOND_PHASE)
spi->mode |= SPI_CPHA;
if (sb->clock_polarity == ACPI_SPI_START_HIGH)
spi->mode |= SPI_CPOL;
if (sb->device_polarity == ACPI_SPI_ACTIVE_HIGH)
spi->mode |= SPI_CS_HIGH;
}
} else if (spi->irq < 0) {
struct resource r;
if (acpi_dev_resource_interrupt(ares, 0, &r))
spi->irq = r.start;
}
/* Always tell the ACPI core to skip this resource */
return 1;
}
static acpi_status acpi_spi_add_device(acpi_handle handle, u32 level,
void *data, void **return_value)
{
struct spi_master *master = data;
struct list_head resource_list;
struct acpi_device *adev;
struct spi_device *spi;
int ret;
if (acpi_bus_get_device(handle, &adev))
return AE_OK;
if (acpi_bus_get_status(adev) || !adev->status.present)
return AE_OK;
spi = spi_alloc_device(master);
if (!spi) {
dev_err(&master->dev, "failed to allocate SPI device for %s\n",
dev_name(&adev->dev));
return AE_NO_MEMORY;
}
ACPI_COMPANION_SET(&spi->dev, adev);
spi->irq = -1;
INIT_LIST_HEAD(&resource_list);
ret = acpi_dev_get_resources(adev, &resource_list,
acpi_spi_add_resource, spi);
acpi_dev_free_resource_list(&resource_list);
if (ret < 0 || !spi->max_speed_hz) {
spi_dev_put(spi);
return AE_OK;
}
adev->power.flags.ignore_parent = true;
strlcpy(spi->modalias, acpi_device_hid(adev), sizeof(spi->modalias));
if (spi_add_device(spi)) {
adev->power.flags.ignore_parent = false;
dev_err(&master->dev, "failed to add SPI device %s from ACPI\n",
dev_name(&adev->dev));
spi_dev_put(spi);
}
return AE_OK;
}
static void acpi_register_spi_devices(struct spi_master *master)
{
acpi_status status;
acpi_handle handle;
handle = ACPI_HANDLE(master->dev.parent);
if (!handle)
return;
status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
acpi_spi_add_device, NULL,
master, NULL);
if (ACPI_FAILURE(status))
dev_warn(&master->dev, "failed to enumerate SPI slaves\n");
}
#else
static inline void acpi_register_spi_devices(struct spi_master *master) {}
#endif /* CONFIG_ACPI */
static void spi_master_release(struct device *dev)
{
struct spi_master *master;
master = container_of(dev, struct spi_master, dev);
kfree(master);
}
static struct class spi_master_class = {
.name = "spi_master",
.owner = THIS_MODULE,
.dev_release = spi_master_release,
.dev_groups = spi_master_groups,
};
/**
* spi_alloc_master - allocate SPI master controller
* @dev: the controller, possibly using the platform_bus
* @size: how much zeroed driver-private data to allocate; the pointer to this
* memory is in the driver_data field of the returned device,
* accessible with spi_master_get_devdata().
* Context: can sleep
*
* This call is used only by SPI master controller drivers, which are the
* only ones directly touching chip registers. It's how they allocate
* an spi_master structure, prior to calling spi_register_master().
*
* This must be called from context that can sleep. It returns the SPI
* master structure on success, else NULL.
*
* The caller is responsible for assigning the bus number and initializing
* the master's methods before calling spi_register_master(); and (after errors
* adding the device) calling spi_master_put() and kfree() to prevent a memory
* leak.
*/
struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
{
struct spi_master *master;
if (!dev)
return NULL;
master = kzalloc(size + sizeof(*master), GFP_KERNEL);
if (!master)
return NULL;
device_initialize(&master->dev);
master->bus_num = -1;
master->num_chipselect = 1;
master->dev.class = &spi_master_class;
master->dev.parent = get_device(dev);
spi_master_set_devdata(master, &master[1]);
return master;
}
EXPORT_SYMBOL_GPL(spi_alloc_master);
#ifdef CONFIG_OF
static int of_spi_register_master(struct spi_master *master)
{
int nb, i, *cs;
struct device_node *np = master->dev.of_node;
if (!np)
return 0;
nb = of_gpio_named_count(np, "cs-gpios");
master->num_chipselect = max_t(int, nb, master->num_chipselect);
/* Return error only for an incorrectly formed cs-gpios property */
if (nb == 0 || nb == -ENOENT)
return 0;
else if (nb < 0)
return nb;
cs = devm_kzalloc(&master->dev,
sizeof(int) * master->num_chipselect,
GFP_KERNEL);
master->cs_gpios = cs;
if (!master->cs_gpios)
return -ENOMEM;
for (i = 0; i < master->num_chipselect; i++)
cs[i] = -ENOENT;
for (i = 0; i < nb; i++)
cs[i] = of_get_named_gpio(np, "cs-gpios", i);
return 0;
}
#else
static int of_spi_register_master(struct spi_master *master)
{
return 0;
}
#endif
/**
* spi_register_master - register SPI master controller
* @master: initialized master, originally from spi_alloc_master()
* Context: can sleep
*
* SPI master controllers connect to their drivers using some non-SPI bus,
* such as the platform bus. The final stage of probe() in that code
* includes calling spi_register_master() to hook up to this SPI bus glue.
*
* SPI controllers use board specific (often SOC specific) bus numbers,
* and board-specific addressing for SPI devices combines those numbers
* with chip select numbers. Since SPI does not directly support dynamic
* device identification, boards need configuration tables telling which
* chip is at which address.
*
* This must be called from context that can sleep. It returns zero on
* success, else a negative error code (dropping the master's refcount).
* After a successful return, the caller is responsible for calling
* spi_unregister_master().
*/
int spi_register_master(struct spi_master *master)
{
static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
struct device *dev = master->dev.parent;
struct boardinfo *bi;
int status = -ENODEV;
int dynamic = 0;
if (!dev)
return -ENODEV;
status = of_spi_register_master(master);
if (status)
return status;
/* even if it's just one always-selected device, there must
* be at least one chipselect
*/
if (master->num_chipselect == 0)
return -EINVAL;
if ((master->bus_num < 0) && master->dev.of_node)
master->bus_num = of_alias_get_id(master->dev.of_node, "spi");
/* convention: dynamically assigned bus IDs count down from the max */
if (master->bus_num < 0) {
/* FIXME switch to an IDR based scheme, something like
* I2C now uses, so we can't run out of "dynamic" IDs
*/
master->bus_num = atomic_dec_return(&dyn_bus_id);
dynamic = 1;
}
INIT_LIST_HEAD(&master->queue);
spin_lock_init(&master->queue_lock);
spin_lock_init(&master->bus_lock_spinlock);
mutex_init(&master->bus_lock_mutex);
master->bus_lock_flag = 0;
init_completion(&master->xfer_completion);
if (!master->max_dma_len)
master->max_dma_len = INT_MAX;
/* register the device, then userspace will see it.
* registration fails if the bus ID is in use.
*/
dev_set_name(&master->dev, "spi%u", master->bus_num);
status = device_add(&master->dev);
if (status < 0)
goto done;
dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
dynamic ? " (dynamic)" : "");
/* If we're using a queued driver, start the queue */
if (master->transfer)
dev_info(dev, "master is unqueued, this is deprecated\n");
else {
status = spi_master_initialize_queue(master);
if (status) {
device_del(&master->dev);
goto done;
}
}
/* add statistics */
spin_lock_init(&master->statistics.lock);
mutex_lock(&board_lock);
list_add_tail(&master->list, &spi_master_list);
list_for_each_entry(bi, &board_list, list)
spi_match_master_to_boardinfo(master, &bi->board_info);
mutex_unlock(&board_lock);
/* Register devices from the device tree and ACPI */
of_register_spi_devices(master);
acpi_register_spi_devices(master);
done:
return status;
}
EXPORT_SYMBOL_GPL(spi_register_master);
static void devm_spi_unregister(struct device *dev, void *res)
{
spi_unregister_master(*(struct spi_master **)res);
}
/**
* dev_spi_register_master - register managed SPI master controller
* @dev: device managing SPI master
* @master: initialized master, originally from spi_alloc_master()
* Context: can sleep
*
* Register a SPI device as with spi_register_master() which will
* automatically be unregister
*/
int devm_spi_register_master(struct device *dev, struct spi_master *master)
{
struct spi_master **ptr;
int ret;
ptr = devres_alloc(devm_spi_unregister, sizeof(*ptr), GFP_KERNEL);
if (!ptr)
return -ENOMEM;
ret = spi_register_master(master);
if (!ret) {
*ptr = master;
devres_add(dev, ptr);
} else {
devres_free(ptr);
}
return ret;
}
EXPORT_SYMBOL_GPL(devm_spi_register_master);
static int __unregister(struct device *dev, void *null)
{
spi_unregister_device(to_spi_device(dev));
return 0;
}
/**
* spi_unregister_master - unregister SPI master controller
* @master: the master being unregistered
* Context: can sleep
*
* This call is used only by SPI master controller drivers, which are the
* only ones directly touching chip registers.
*
* This must be called from context that can sleep.
*/
void spi_unregister_master(struct spi_master *master)
{
int dummy;
if (master->queued) {
if (spi_destroy_queue(master))
dev_err(&master->dev, "queue remove failed\n");
}
mutex_lock(&board_lock);
list_del(&master->list);
mutex_unlock(&board_lock);
dummy = device_for_each_child(&master->dev, NULL, __unregister);
device_unregister(&master->dev);
}
EXPORT_SYMBOL_GPL(spi_unregister_master);
int spi_master_suspend(struct spi_master *master)
{
int ret;
/* Basically no-ops for non-queued masters */
if (!master->queued)
return 0;
ret = spi_stop_queue(master);
if (ret)
dev_err(&master->dev, "queue stop failed\n");
return ret;
}
EXPORT_SYMBOL_GPL(spi_master_suspend);
int spi_master_resume(struct spi_master *master)
{
int ret;
if (!master->queued)
return 0;
ret = spi_start_queue(master);
if (ret)
dev_err(&master->dev, "queue restart failed\n");
return ret;
}
EXPORT_SYMBOL_GPL(spi_master_resume);
static int __spi_master_match(struct device *dev, const void *data)
{
struct spi_master *m;
const u16 *bus_num = data;
m = container_of(dev, struct spi_master, dev);
return m->bus_num == *bus_num;
}
/**
* spi_busnum_to_master - look up master associated with bus_num
* @bus_num: the master's bus number
* Context: can sleep
*
* This call may be used with devices that are registered after
* arch init time. It returns a refcounted pointer to the relevant
* spi_master (which the caller must release), or NULL if there is
* no such master registered.
*/
struct spi_master *spi_busnum_to_master(u16 bus_num)
{
struct device *dev;
struct spi_master *master = NULL;
dev = class_find_device(&spi_master_class, NULL, &bus_num,
__spi_master_match);
if (dev)
master = container_of(dev, struct spi_master, dev);
/* reference got in class_find_device */
return master;
}
EXPORT_SYMBOL_GPL(spi_busnum_to_master);
/*-------------------------------------------------------------------------*/
/* Core methods for SPI master protocol drivers. Some of the
* other core methods are currently defined as inline functions.
*/
static int __spi_validate_bits_per_word(struct spi_master *master, u8 bits_per_word)
{
if (master->bits_per_word_mask) {
/* Only 32 bits fit in the mask */
if (bits_per_word > 32)
return -EINVAL;
if (!(master->bits_per_word_mask &
SPI_BPW_MASK(bits_per_word)))
return -EINVAL;
}
return 0;
}
/**
* spi_setup - setup SPI mode and clock rate
* @spi: the device whose settings are being modified
* Context: can sleep, and no requests are queued to the device
*
* SPI protocol drivers may need to update the transfer mode if the
* device doesn't work with its default. They may likewise need
* to update clock rates or word sizes from initial values. This function
* changes those settings, and must be called from a context that can sleep.
* Except for SPI_CS_HIGH, which takes effect immediately, the changes take
* effect the next time the device is selected and data is transferred to
* or from it. When this function returns, the spi device is deselected.
*
* Note that this call will fail if the protocol driver specifies an option
* that the underlying controller or its driver does not support. For
* example, not all hardware supports wire transfers using nine bit words,
* LSB-first wire encoding, or active-high chipselects.
*/
int spi_setup(struct spi_device *spi)
{
unsigned bad_bits, ugly_bits;
int status = 0;
/* check mode to prevent that DUAL and QUAD set at the same time
*/
if (((spi->mode & SPI_TX_DUAL) && (spi->mode & SPI_TX_QUAD)) ||
((spi->mode & SPI_RX_DUAL) && (spi->mode & SPI_RX_QUAD))) {
dev_err(&spi->dev,
"setup: can not select dual and quad at the same time\n");
return -EINVAL;
}
/* if it is SPI_3WIRE mode, DUAL and QUAD should be forbidden
*/
if ((spi->mode & SPI_3WIRE) && (spi->mode &
(SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)))
return -EINVAL;
/* help drivers fail *cleanly* when they need options
* that aren't supported with their current master
*/
bad_bits = spi->mode & ~spi->master->mode_bits;
ugly_bits = bad_bits &
(SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD);
if (ugly_bits) {
dev_warn(&spi->dev,
"setup: ignoring unsupported mode bits %x\n",
ugly_bits);
spi->mode &= ~ugly_bits;
bad_bits &= ~ugly_bits;
}
if (bad_bits) {
dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
bad_bits);
return -EINVAL;
}
if (!spi->bits_per_word)
spi->bits_per_word = 8;
if (__spi_validate_bits_per_word(spi->master, spi->bits_per_word))
return -EINVAL;
if (!spi->max_speed_hz)
spi->max_speed_hz = spi->master->max_speed_hz;
spi_set_cs(spi, false);
if (spi->master->setup)
status = spi->master->setup(spi);
dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s%u bits/w, %u Hz max --> %d\n",
(int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
(spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
(spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
(spi->mode & SPI_3WIRE) ? "3wire, " : "",
(spi->mode & SPI_LOOP) ? "loopback, " : "",
spi->bits_per_word, spi->max_speed_hz,
status);
return status;
}
EXPORT_SYMBOL_GPL(spi_setup);
static int __spi_validate(struct spi_device *spi, struct spi_message *message)
{
struct spi_master *master = spi->master;
struct spi_transfer *xfer;
int w_size;
if (list_empty(&message->transfers))
return -EINVAL;
/* Half-duplex links include original MicroWire, and ones with
* only one data pin like SPI_3WIRE (switches direction) or where
* either MOSI or MISO is missing. They can also be caused by
* software limitations.
*/
if ((master->flags & SPI_MASTER_HALF_DUPLEX)
|| (spi->mode & SPI_3WIRE)) {
unsigned flags = master->flags;
list_for_each_entry(xfer, &message->transfers, transfer_list) {
if (xfer->rx_buf && xfer->tx_buf)
return -EINVAL;
if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
return -EINVAL;
if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
return -EINVAL;
}
}
/**
* Set transfer bits_per_word and max speed as spi device default if
* it is not set for this transfer.
* Set transfer tx_nbits and rx_nbits as single transfer default
* (SPI_NBITS_SINGLE) if it is not set for this transfer.
*/
list_for_each_entry(xfer, &message->transfers, transfer_list) {
message->frame_length += xfer->len;
if (!xfer->bits_per_word)
xfer->bits_per_word = spi->bits_per_word;
if (!xfer->speed_hz)
xfer->speed_hz = spi->max_speed_hz;
if (!xfer->speed_hz)
xfer->speed_hz = master->max_speed_hz;
if (master->max_speed_hz &&
xfer->speed_hz > master->max_speed_hz)
xfer->speed_hz = master->max_speed_hz;
if (__spi_validate_bits_per_word(master, xfer->bits_per_word))
return -EINVAL;
/*
* SPI transfer length should be multiple of SPI word size
* where SPI word size should be power-of-two multiple
*/
if (xfer->bits_per_word <= 8)
w_size = 1;
else if (xfer->bits_per_word <= 16)
w_size = 2;
else
w_size = 4;
/* No partial transfers accepted */
if (xfer->len % w_size)
return -EINVAL;
if (xfer->speed_hz && master->min_speed_hz &&
xfer->speed_hz < master->min_speed_hz)
return -EINVAL;
if (xfer->tx_buf && !xfer->tx_nbits)
xfer->tx_nbits = SPI_NBITS_SINGLE;
if (xfer->rx_buf && !xfer->rx_nbits)
xfer->rx_nbits = SPI_NBITS_SINGLE;
/* check transfer tx/rx_nbits:
* 1. check the value matches one of single, dual and quad
* 2. check tx/rx_nbits match the mode in spi_device
*/
if (xfer->tx_buf) {
if (xfer->tx_nbits != SPI_NBITS_SINGLE &&
xfer->tx_nbits != SPI_NBITS_DUAL &&
xfer->tx_nbits != SPI_NBITS_QUAD)
return -EINVAL;
if ((xfer->tx_nbits == SPI_NBITS_DUAL) &&
!(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
return -EINVAL;
if ((xfer->tx_nbits == SPI_NBITS_QUAD) &&
!(spi->mode & SPI_TX_QUAD))
return -EINVAL;
}
/* check transfer rx_nbits */
if (xfer->rx_buf) {
if (xfer->rx_nbits != SPI_NBITS_SINGLE &&
xfer->rx_nbits != SPI_NBITS_DUAL &&
xfer->rx_nbits != SPI_NBITS_QUAD)
return -EINVAL;
if ((xfer->rx_nbits == SPI_NBITS_DUAL) &&
!(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))
return -EINVAL;
if ((xfer->rx_nbits == SPI_NBITS_QUAD) &&
!(spi->mode & SPI_RX_QUAD))
return -EINVAL;
}
}
message->status = -EINPROGRESS;
return 0;
}
static int __spi_async(struct spi_device *spi, struct spi_message *message)
{
struct spi_master *master = spi->master;
message->spi = spi;
SPI_STATISTICS_INCREMENT_FIELD(&master->statistics, spi_async);
SPI_STATISTICS_INCREMENT_FIELD(&spi->statistics, spi_async);
trace_spi_message_submit(message);
return master->transfer(spi, message);
}
/**
* spi_async - asynchronous SPI transfer
* @spi: device with which data will be exchanged
* @message: describes the data transfers, including completion callback
* Context: any (irqs may be blocked, etc)
*
* This call may be used in_irq and other contexts which can't sleep,
* as well as from task contexts which can sleep.
*
* The completion callback is invoked in a context which can't sleep.
* Before that invocation, the value of message->status is undefined.
* When the callback is issued, message->status holds either zero (to
* indicate complete success) or a negative error code. After that
* callback returns, the driver which issued the transfer request may
* deallocate the associated memory; it's no longer in use by any SPI
* core or controller driver code.
*
* Note that although all messages to a spi_device are handled in
* FIFO order, messages may go to different devices in other orders.
* Some device might be higher priority, or have various "hard" access
* time requirements, for example.
*
* On detection of any fault during the transfer, processing of
* the entire message is aborted, and the device is deselected.
* Until returning from the associated message completion callback,
* no other spi_message queued to that device will be processed.
* (This rule applies equally to all the synchronous transfer calls,
* which are wrappers around this core asynchronous primitive.)
*/
int spi_async(struct spi_device *spi, struct spi_message *message)
{
struct spi_master *master = spi->master;
int ret;
unsigned long flags;
ret = __spi_validate(spi, message);
if (ret != 0)
return ret;
spin_lock_irqsave(&master->bus_lock_spinlock, flags);
if (master->bus_lock_flag)
ret = -EBUSY;
else
ret = __spi_async(spi, message);
spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
return ret;
}
EXPORT_SYMBOL_GPL(spi_async);
/**
* spi_async_locked - version of spi_async with exclusive bus usage
* @spi: device with which data will be exchanged
* @message: describes the data transfers, including completion callback
* Context: any (irqs may be blocked, etc)
*
* This call may be used in_irq and other contexts which can't sleep,
* as well as from task contexts which can sleep.
*
* The completion callback is invoked in a context which can't sleep.
* Before that invocation, the value of message->status is undefined.
* When the callback is issued, message->status holds either zero (to
* indicate complete success) or a negative error code. After that
* callback returns, the driver which issued the transfer request may
* deallocate the associated memory; it's no longer in use by any SPI
* core or controller driver code.
*
* Note that although all messages to a spi_device are handled in
* FIFO order, messages may go to different devices in other orders.
* Some device might be higher priority, or have various "hard" access
* time requirements, for example.
*
* On detection of any fault during the transfer, processing of
* the entire message is aborted, and the device is deselected.
* Until returning from the associated message completion callback,
* no other spi_message queued to that device will be processed.
* (This rule applies equally to all the synchronous transfer calls,
* which are wrappers around this core asynchronous primitive.)
*/
int spi_async_locked(struct spi_device *spi, struct spi_message *message)
{
struct spi_master *master = spi->master;
int ret;
unsigned long flags;
ret = __spi_validate(spi, message);
if (ret != 0)
return ret;
spin_lock_irqsave(&master->bus_lock_spinlock, flags);
ret = __spi_async(spi, message);
spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
return ret;
}
EXPORT_SYMBOL_GPL(spi_async_locked);
/*-------------------------------------------------------------------------*/
/* Utility methods for SPI master protocol drivers, layered on
* top of the core. Some other utility methods are defined as
* inline functions.
*/
static void spi_complete(void *arg)
{
complete(arg);
}
static int __spi_sync(struct spi_device *spi, struct spi_message *message,
int bus_locked)
{
DECLARE_COMPLETION_ONSTACK(done);
int status;
struct spi_master *master = spi->master;
unsigned long flags;
status = __spi_validate(spi, message);
if (status != 0)
return status;
message->complete = spi_complete;
message->context = &done;
message->spi = spi;
SPI_STATISTICS_INCREMENT_FIELD(&master->statistics, spi_sync);
SPI_STATISTICS_INCREMENT_FIELD(&spi->statistics, spi_sync);
if (!bus_locked)
mutex_lock(&master->bus_lock_mutex);
/* If we're not using the legacy transfer method then we will
* try to transfer in the calling context so special case.
* This code would be less tricky if we could remove the
* support for driver implemented message queues.
*/
if (master->transfer == spi_queued_transfer) {
spin_lock_irqsave(&master->bus_lock_spinlock, flags);
trace_spi_message_submit(message);
status = __spi_queued_transfer(spi, message, false);
spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
} else {
status = spi_async_locked(spi, message);
}
if (!bus_locked)
mutex_unlock(&master->bus_lock_mutex);
if (status == 0) {
/* Push out the messages in the calling context if we
* can.
*/
if (master->transfer == spi_queued_transfer) {
SPI_STATISTICS_INCREMENT_FIELD(&master->statistics,
spi_sync_immediate);
SPI_STATISTICS_INCREMENT_FIELD(&spi->statistics,
spi_sync_immediate);
__spi_pump_messages(master, false);
}
wait_for_completion(&done);
status = message->status;
}
message->context = NULL;
return status;
}
/**
* spi_sync - blocking/synchronous SPI data transfers
* @spi: device with which data will be exchanged
* @message: describes the data transfers
* Context: can sleep
*
* This call may only be used from a context that may sleep. The sleep
* is non-interruptible, and has no timeout. Low-overhead controller
* drivers may DMA directly into and out of the message buffers.
*
* Note that the SPI device's chip select is active during the message,
* and then is normally disabled between messages. Drivers for some
* frequently-used devices may want to minimize costs of selecting a chip,
* by leaving it selected in anticipation that the next message will go
* to the same chip. (That may increase power usage.)
*
* Also, the caller is guaranteeing that the memory associated with the
* message will not be freed before this call returns.
*
* It returns zero on success, else a negative error code.
*/
int spi_sync(struct spi_device *spi, struct spi_message *message)
{
return __spi_sync(spi, message, 0);
}
EXPORT_SYMBOL_GPL(spi_sync);
/**
* spi_sync_locked - version of spi_sync with exclusive bus usage
* @spi: device with which data will be exchanged
* @message: describes the data transfers
* Context: can sleep
*
* This call may only be used from a context that may sleep. The sleep
* is non-interruptible, and has no timeout. Low-overhead controller
* drivers may DMA directly into and out of the message buffers.
*
* This call should be used by drivers that require exclusive access to the
* SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
* be released by a spi_bus_unlock call when the exclusive access is over.
*
* It returns zero on success, else a negative error code.
*/
int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
{
return __spi_sync(spi, message, 1);
}
EXPORT_SYMBOL_GPL(spi_sync_locked);
/**
* spi_bus_lock - obtain a lock for exclusive SPI bus usage
* @master: SPI bus master that should be locked for exclusive bus access
* Context: can sleep
*
* This call may only be used from a context that may sleep. The sleep
* is non-interruptible, and has no timeout.
*
* This call should be used by drivers that require exclusive access to the
* SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
* exclusive access is over. Data transfer must be done by spi_sync_locked
* and spi_async_locked calls when the SPI bus lock is held.
*
* It returns zero on success, else a negative error code.
*/
int spi_bus_lock(struct spi_master *master)
{
unsigned long flags;
mutex_lock(&master->bus_lock_mutex);
spin_lock_irqsave(&master->bus_lock_spinlock, flags);
master->bus_lock_flag = 1;
spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
/* mutex remains locked until spi_bus_unlock is called */
return 0;
}
EXPORT_SYMBOL_GPL(spi_bus_lock);
/**
* spi_bus_unlock - release the lock for exclusive SPI bus usage
* @master: SPI bus master that was locked for exclusive bus access
* Context: can sleep
*
* This call may only be used from a context that may sleep. The sleep
* is non-interruptible, and has no timeout.
*
* This call releases an SPI bus lock previously obtained by an spi_bus_lock
* call.
*
* It returns zero on success, else a negative error code.
*/
int spi_bus_unlock(struct spi_master *master)
{
master->bus_lock_flag = 0;
mutex_unlock(&master->bus_lock_mutex);
return 0;
}
EXPORT_SYMBOL_GPL(spi_bus_unlock);
/* portable code must never pass more than 32 bytes */
#define SPI_BUFSIZ max(32, SMP_CACHE_BYTES)
static u8 *buf;
/**
* spi_write_then_read - SPI synchronous write followed by read
* @spi: device with which data will be exchanged
* @txbuf: data to be written (need not be dma-safe)
* @n_tx: size of txbuf, in bytes
* @rxbuf: buffer into which data will be read (need not be dma-safe)
* @n_rx: size of rxbuf, in bytes
* Context: can sleep
*
* This performs a half duplex MicroWire style transaction with the
* device, sending txbuf and then reading rxbuf. The return value
* is zero for success, else a negative errno status code.
* This call may only be used from a context that may sleep.
*
* Parameters to this routine are always copied using a small buffer;
* portable code should never use this for more than 32 bytes.
* Performance-sensitive or bulk transfer code should instead use
* spi_{async,sync}() calls with dma-safe buffers.
*/
int spi_write_then_read(struct spi_device *spi,
const void *txbuf, unsigned n_tx,
void *rxbuf, unsigned n_rx)
{
static DEFINE_MUTEX(lock);
int status;
struct spi_message message;
struct spi_transfer x[2];
u8 *local_buf;
/* Use preallocated DMA-safe buffer if we can. We can't avoid
* copying here, (as a pure convenience thing), but we can
* keep heap costs out of the hot path unless someone else is
* using the pre-allocated buffer or the transfer is too large.
*/
if ((n_tx + n_rx) > SPI_BUFSIZ || !mutex_trylock(&lock)) {
local_buf = kmalloc(max((unsigned)SPI_BUFSIZ, n_tx + n_rx),
GFP_KERNEL | GFP_DMA);
if (!local_buf)
return -ENOMEM;
} else {
local_buf = buf;
}
spi_message_init(&message);
memset(x, 0, sizeof(x));
if (n_tx) {
x[0].len = n_tx;
spi_message_add_tail(&x[0], &message);
}
if (n_rx) {
x[1].len = n_rx;
spi_message_add_tail(&x[1], &message);
}
memcpy(local_buf, txbuf, n_tx);
x[0].tx_buf = local_buf;
x[1].rx_buf = local_buf + n_tx;
/* do the i/o */
status = spi_sync(spi, &message);
if (status == 0)
memcpy(rxbuf, x[1].rx_buf, n_rx);
if (x[0].tx_buf == buf)
mutex_unlock(&lock);
else
kfree(local_buf);
return status;
}
EXPORT_SYMBOL_GPL(spi_write_then_read);
/*-------------------------------------------------------------------------*/
#if IS_ENABLED(CONFIG_OF_DYNAMIC)
static int __spi_of_device_match(struct device *dev, void *data)
{
return dev->of_node == data;
}
/* must call put_device() when done with returned spi_device device */
static struct spi_device *of_find_spi_device_by_node(struct device_node *node)
{
struct device *dev = bus_find_device(&spi_bus_type, NULL, node,
__spi_of_device_match);
return dev ? to_spi_device(dev) : NULL;
}
static int __spi_of_master_match(struct device *dev, const void *data)
{
return dev->of_node == data;
}
/* the spi masters are not using spi_bus, so we find it with another way */
static struct spi_master *of_find_spi_master_by_node(struct device_node *node)
{
struct device *dev;
dev = class_find_device(&spi_master_class, NULL, node,
__spi_of_master_match);
if (!dev)
return NULL;
/* reference got in class_find_device */
return container_of(dev, struct spi_master, dev);
}
static int of_spi_notify(struct notifier_block *nb, unsigned long action,
void *arg)
{
struct of_reconfig_data *rd = arg;
struct spi_master *master;
struct spi_device *spi;
switch (of_reconfig_get_state_change(action, arg)) {
case OF_RECONFIG_CHANGE_ADD:
master = of_find_spi_master_by_node(rd->dn->parent);
if (master == NULL)
return NOTIFY_OK; /* not for us */
spi = of_register_spi_device(master, rd->dn);
put_device(&master->dev);
if (IS_ERR(spi)) {
pr_err("%s: failed to create for '%s'\n",
__func__, rd->dn->full_name);
return notifier_from_errno(PTR_ERR(spi));
}
break;
case OF_RECONFIG_CHANGE_REMOVE:
/* find our device by node */
spi = of_find_spi_device_by_node(rd->dn);
if (spi == NULL)
return NOTIFY_OK; /* no? not meant for us */
/* unregister takes one ref away */
spi_unregister_device(spi);
/* and put the reference of the find */
put_device(&spi->dev);
break;
}
return NOTIFY_OK;
}
static struct notifier_block spi_of_notifier = {
.notifier_call = of_spi_notify,
};
#else /* IS_ENABLED(CONFIG_OF_DYNAMIC) */
extern struct notifier_block spi_of_notifier;
#endif /* IS_ENABLED(CONFIG_OF_DYNAMIC) */
static int __init spi_init(void)
{
int status;
buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
if (!buf) {
status = -ENOMEM;
goto err0;
}
status = bus_register(&spi_bus_type);
if (status < 0)
goto err1;
status = class_register(&spi_master_class);
if (status < 0)
goto err2;
if (IS_ENABLED(CONFIG_OF_DYNAMIC))
WARN_ON(of_reconfig_notifier_register(&spi_of_notifier));
return 0;
err2:
bus_unregister(&spi_bus_type);
err1:
kfree(buf);
buf = NULL;
err0:
return status;
}
/* board_info is normally registered in arch_initcall(),
* but even essential drivers wait till later
*
* REVISIT only boardinfo really needs static linking. the rest (device and
* driver registration) _could_ be dynamically linked (modular) ... costs
* include needing to have boardinfo data structures be much more public.
*/
postcore_initcall(spi_init);
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