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OpenCloudOS-Kernel/include/linux/spi/spi.h

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/*
* Copyright (C) 2005 David Brownell
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifndef __LINUX_SPI_H
#define __LINUX_SPI_H
#include <linux/device.h>
#include <linux/mod_devicetable.h>
#include <linux/slab.h>
#include <linux/kthread.h>
/*
* INTERFACES between SPI master-side drivers and SPI infrastructure.
* (There's no SPI slave support for Linux yet...)
*/
extern struct bus_type spi_bus_type;
/**
* struct spi_device - Master side proxy for an SPI slave device
* @dev: Driver model representation of the device.
* @master: SPI controller used with the device.
* @max_speed_hz: Maximum clock rate to be used with this chip
* (on this board); may be changed by the device's driver.
* The spi_transfer.speed_hz can override this for each transfer.
* @chip_select: Chipselect, distinguishing chips handled by @master.
* @mode: The spi mode defines how data is clocked out and in.
* This may be changed by the device's driver.
* The "active low" default for chipselect mode can be overridden
* (by specifying SPI_CS_HIGH) as can the "MSB first" default for
* each word in a transfer (by specifying SPI_LSB_FIRST).
* @bits_per_word: Data transfers involve one or more words; word sizes
* like eight or 12 bits are common. In-memory wordsizes are
* powers of two bytes (e.g. 20 bit samples use 32 bits).
* This may be changed by the device's driver, or left at the
* default (0) indicating protocol words are eight bit bytes.
* The spi_transfer.bits_per_word can override this for each transfer.
* @irq: Negative, or the number passed to request_irq() to receive
* interrupts from this device.
* @controller_state: Controller's runtime state
* @controller_data: Board-specific definitions for controller, such as
* FIFO initialization parameters; from board_info.controller_data
* @modalias: Name of the driver to use with this device, or an alias
* for that name. This appears in the sysfs "modalias" attribute
* for driver coldplugging, and in uevents used for hotplugging
*
* A @spi_device is used to interchange data between an SPI slave
* (usually a discrete chip) and CPU memory.
*
* In @dev, the platform_data is used to hold information about this
* device that's meaningful to the device's protocol driver, but not
* to its controller. One example might be an identifier for a chip
* variant with slightly different functionality; another might be
* information about how this particular board wires the chip's pins.
*/
struct spi_device {
struct device dev;
struct spi_master *master;
u32 max_speed_hz;
u8 chip_select;
u8 mode;
#define SPI_CPHA 0x01 /* clock phase */
#define SPI_CPOL 0x02 /* clock polarity */
#define SPI_MODE_0 (0|0) /* (original MicroWire) */
#define SPI_MODE_1 (0|SPI_CPHA)
#define SPI_MODE_2 (SPI_CPOL|0)
#define SPI_MODE_3 (SPI_CPOL|SPI_CPHA)
#define SPI_CS_HIGH 0x04 /* chipselect active high? */
#define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */
#define SPI_3WIRE 0x10 /* SI/SO signals shared */
#define SPI_LOOP 0x20 /* loopback mode */
#define SPI_NO_CS 0x40 /* 1 dev/bus, no chipselect */
#define SPI_READY 0x80 /* slave pulls low to pause */
u8 bits_per_word;
int irq;
void *controller_state;
void *controller_data;
char modalias[SPI_NAME_SIZE];
/*
* likely need more hooks for more protocol options affecting how
* the controller talks to each chip, like:
* - memory packing (12 bit samples into low bits, others zeroed)
* - priority
* - drop chipselect after each word
* - chipselect delays
* - ...
*/
};
static inline struct spi_device *to_spi_device(struct device *dev)
{
return dev ? container_of(dev, struct spi_device, dev) : NULL;
}
/* most drivers won't need to care about device refcounting */
static inline struct spi_device *spi_dev_get(struct spi_device *spi)
{
return (spi && get_device(&spi->dev)) ? spi : NULL;
}
static inline void spi_dev_put(struct spi_device *spi)
{
if (spi)
put_device(&spi->dev);
}
/* ctldata is for the bus_master driver's runtime state */
static inline void *spi_get_ctldata(struct spi_device *spi)
{
return spi->controller_state;
}
static inline void spi_set_ctldata(struct spi_device *spi, void *state)
{
spi->controller_state = state;
}
/* device driver data */
static inline void spi_set_drvdata(struct spi_device *spi, void *data)
{
dev_set_drvdata(&spi->dev, data);
}
static inline void *spi_get_drvdata(struct spi_device *spi)
{
return dev_get_drvdata(&spi->dev);
}
struct spi_message;
/**
* struct spi_driver - Host side "protocol" driver
* @id_table: List of SPI devices supported by this driver
* @probe: Binds this driver to the spi device. Drivers can verify
* that the device is actually present, and may need to configure
* characteristics (such as bits_per_word) which weren't needed for
* the initial configuration done during system setup.
* @remove: Unbinds this driver from the spi device
* @shutdown: Standard shutdown callback used during system state
* transitions such as powerdown/halt and kexec
* @suspend: Standard suspend callback used during system state transitions
* @resume: Standard resume callback used during system state transitions
* @driver: SPI device drivers should initialize the name and owner
* field of this structure.
*
* This represents the kind of device driver that uses SPI messages to
* interact with the hardware at the other end of a SPI link. It's called
* a "protocol" driver because it works through messages rather than talking
* directly to SPI hardware (which is what the underlying SPI controller
* driver does to pass those messages). These protocols are defined in the
* specification for the device(s) supported by the driver.
*
* As a rule, those device protocols represent the lowest level interface
* supported by a driver, and it will support upper level interfaces too.
* Examples of such upper levels include frameworks like MTD, networking,
* MMC, RTC, filesystem character device nodes, and hardware monitoring.
*/
struct spi_driver {
const struct spi_device_id *id_table;
int (*probe)(struct spi_device *spi);
int (*remove)(struct spi_device *spi);
void (*shutdown)(struct spi_device *spi);
int (*suspend)(struct spi_device *spi, pm_message_t mesg);
int (*resume)(struct spi_device *spi);
struct device_driver driver;
};
static inline struct spi_driver *to_spi_driver(struct device_driver *drv)
{
return drv ? container_of(drv, struct spi_driver, driver) : NULL;
}
extern int spi_register_driver(struct spi_driver *sdrv);
/**
* spi_unregister_driver - reverse effect of spi_register_driver
* @sdrv: the driver to unregister
* Context: can sleep
*/
static inline void spi_unregister_driver(struct spi_driver *sdrv)
{
if (sdrv)
driver_unregister(&sdrv->driver);
}
/**
* module_spi_driver() - Helper macro for registering a SPI driver
* @__spi_driver: spi_driver struct
*
* Helper macro for SPI drivers which do not do anything special in module
* init/exit. This eliminates a lot of boilerplate. Each module may only
* use this macro once, and calling it replaces module_init() and module_exit()
*/
#define module_spi_driver(__spi_driver) \
module_driver(__spi_driver, spi_register_driver, \
spi_unregister_driver)
/**
* struct spi_master - interface to SPI master controller
* @dev: device interface to this driver
* @list: link with the global spi_master list
* @bus_num: board-specific (and often SOC-specific) identifier for a
* given SPI controller.
* @num_chipselect: chipselects are used to distinguish individual
* SPI slaves, and are numbered from zero to num_chipselects.
* each slave has a chipselect signal, but it's common that not
* every chipselect is connected to a slave.
* @dma_alignment: SPI controller constraint on DMA buffers alignment.
* @mode_bits: flags understood by this controller driver
* @flags: other constraints relevant to this driver
* @bus_lock_spinlock: spinlock for SPI bus locking
* @bus_lock_mutex: mutex for SPI bus locking
* @bus_lock_flag: indicates that the SPI bus is locked for exclusive use
* @setup: updates the device mode and clocking records used by a
* device's SPI controller; protocol code may call this. This
* must fail if an unrecognized or unsupported mode is requested.
* It's always safe to call this unless transfers are pending on
* the device whose settings are being modified.
* @transfer: adds a message to the controller's transfer queue.
* @cleanup: frees controller-specific state
* @queued: whether this master is providing an internal message queue
* @kworker: thread struct for message pump
* @kworker_task: pointer to task for message pump kworker thread
* @pump_messages: work struct for scheduling work to the message pump
* @queue_lock: spinlock to syncronise access to message queue
* @queue: message queue
* @cur_msg: the currently in-flight message
* @busy: message pump is busy
* @running: message pump is running
* @rt: whether this queue is set to run as a realtime task
* @prepare_transfer_hardware: a message will soon arrive from the queue
* so the subsystem requests the driver to prepare the transfer hardware
* by issuing this call
* @transfer_one_message: the subsystem calls the driver to transfer a single
* message while queuing transfers that arrive in the meantime. When the
* driver is finished with this message, it must call
* spi_finalize_current_message() so the subsystem can issue the next
* transfer
* @prepare_transfer_hardware: there are currently no more messages on the
* queue so the subsystem notifies the driver that it may relax the
* hardware by issuing this call
*
* Each SPI master controller can communicate with one or more @spi_device
* children. These make a small bus, sharing MOSI, MISO and SCK signals
* but not chip select signals. Each device may be configured to use a
* different clock rate, since those shared signals are ignored unless
* the chip is selected.
*
* The driver for an SPI controller manages access to those devices through
* a queue of spi_message transactions, copying data between CPU memory and
* an SPI slave device. For each such message it queues, it calls the
* message's completion function when the transaction completes.
*/
struct spi_master {
struct device dev;
struct list_head list;
/* other than negative (== assign one dynamically), bus_num is fully
* board-specific. usually that simplifies to being SOC-specific.
* example: one SOC has three SPI controllers, numbered 0..2,
* and one board's schematics might show it using SPI-2. software
* would normally use bus_num=2 for that controller.
*/
s16 bus_num;
/* chipselects will be integral to many controllers; some others
* might use board-specific GPIOs.
*/
u16 num_chipselect;
/* some SPI controllers pose alignment requirements on DMAable
* buffers; let protocol drivers know about these requirements.
*/
u16 dma_alignment;
/* spi_device.mode flags understood by this controller driver */
u16 mode_bits;
/* other constraints relevant to this driver */
u16 flags;
#define SPI_MASTER_HALF_DUPLEX BIT(0) /* can't do full duplex */
#define SPI_MASTER_NO_RX BIT(1) /* can't do buffer read */
#define SPI_MASTER_NO_TX BIT(2) /* can't do buffer write */
/* lock and mutex for SPI bus locking */
spinlock_t bus_lock_spinlock;
struct mutex bus_lock_mutex;
/* flag indicating that the SPI bus is locked for exclusive use */
bool bus_lock_flag;
/* Setup mode and clock, etc (spi driver may call many times).
*
* IMPORTANT: this may be called when transfers to another
* device are active. DO NOT UPDATE SHARED REGISTERS in ways
* which could break those transfers.
*/
int (*setup)(struct spi_device *spi);
/* bidirectional bulk transfers
*
* + The transfer() method may not sleep; its main role is
* just to add the message to the queue.
* + For now there's no remove-from-queue operation, or
* any other request management
* + To a given spi_device, message queueing is pure fifo
*
* + The master's main job is to process its message queue,
* selecting a chip then transferring data
* + If there are multiple spi_device children, the i/o queue
* arbitration algorithm is unspecified (round robin, fifo,
* priority, reservations, preemption, etc)
*
* + Chipselect stays active during the entire message
* (unless modified by spi_transfer.cs_change != 0).
* + The message transfers use clock and SPI mode parameters
* previously established by setup() for this device
*/
int (*transfer)(struct spi_device *spi,
struct spi_message *mesg);
/* called on release() to free memory provided by spi_master */
void (*cleanup)(struct spi_device *spi);
/*
* These hooks are for drivers that want to use the generic
* master transfer queueing mechanism. If these are used, the
* transfer() function above must NOT be specified by the driver.
* Over time we expect SPI drivers to be phased over to this API.
*/
bool queued;
struct kthread_worker kworker;
struct task_struct *kworker_task;
struct kthread_work pump_messages;
spinlock_t queue_lock;
struct list_head queue;
struct spi_message *cur_msg;
bool busy;
bool running;
bool rt;
int (*prepare_transfer_hardware)(struct spi_master *master);
int (*transfer_one_message)(struct spi_master *master,
struct spi_message *mesg);
int (*unprepare_transfer_hardware)(struct spi_master *master);
};
static inline void *spi_master_get_devdata(struct spi_master *master)
{
return dev_get_drvdata(&master->dev);
}
static inline void spi_master_set_devdata(struct spi_master *master, void *data)
{
dev_set_drvdata(&master->dev, data);
}
static inline struct spi_master *spi_master_get(struct spi_master *master)
{
if (!master || !get_device(&master->dev))
return NULL;
return master;
}
static inline void spi_master_put(struct spi_master *master)
{
if (master)
put_device(&master->dev);
}
/* PM calls that need to be issued by the driver */
extern int spi_master_suspend(struct spi_master *master);
extern int spi_master_resume(struct spi_master *master);
/* Calls the driver make to interact with the message queue */
extern struct spi_message *spi_get_next_queued_message(struct spi_master *master);
extern void spi_finalize_current_message(struct spi_master *master);
/* the spi driver core manages memory for the spi_master classdev */
extern struct spi_master *
spi_alloc_master(struct device *host, unsigned size);
extern int spi_register_master(struct spi_master *master);
extern void spi_unregister_master(struct spi_master *master);
extern struct spi_master *spi_busnum_to_master(u16 busnum);
/*---------------------------------------------------------------------------*/
/*
* I/O INTERFACE between SPI controller and protocol drivers
*
* Protocol drivers use a queue of spi_messages, each transferring data
* between the controller and memory buffers.
*
* The spi_messages themselves consist of a series of read+write transfer
* segments. Those segments always read the same number of bits as they
* write; but one or the other is easily ignored by passing a null buffer
* pointer. (This is unlike most types of I/O API, because SPI hardware
* is full duplex.)
*
* NOTE: Allocation of spi_transfer and spi_message memory is entirely
* up to the protocol driver, which guarantees the integrity of both (as
* well as the data buffers) for as long as the message is queued.
*/
/**
* struct spi_transfer - a read/write buffer pair
* @tx_buf: data to be written (dma-safe memory), or NULL
* @rx_buf: data to be read (dma-safe memory), or NULL
* @tx_dma: DMA address of tx_buf, if @spi_message.is_dma_mapped
* @rx_dma: DMA address of rx_buf, if @spi_message.is_dma_mapped
* @len: size of rx and tx buffers (in bytes)
* @speed_hz: Select a speed other than the device default for this
* transfer. If 0 the default (from @spi_device) is used.
* @bits_per_word: select a bits_per_word other than the device default
* for this transfer. If 0 the default (from @spi_device) is used.
* @cs_change: affects chipselect after this transfer completes
* @delay_usecs: microseconds to delay after this transfer before
* (optionally) changing the chipselect status, then starting
* the next transfer or completing this @spi_message.
* @transfer_list: transfers are sequenced through @spi_message.transfers
*
* SPI transfers always write the same number of bytes as they read.
* Protocol drivers should always provide @rx_buf and/or @tx_buf.
* In some cases, they may also want to provide DMA addresses for
* the data being transferred; that may reduce overhead, when the
* underlying driver uses dma.
*
* If the transmit buffer is null, zeroes will be shifted out
* while filling @rx_buf. If the receive buffer is null, the data
* shifted in will be discarded. Only "len" bytes shift out (or in).
* It's an error to try to shift out a partial word. (For example, by
* shifting out three bytes with word size of sixteen or twenty bits;
* the former uses two bytes per word, the latter uses four bytes.)
*
* In-memory data values are always in native CPU byte order, translated
* from the wire byte order (big-endian except with SPI_LSB_FIRST). So
* for example when bits_per_word is sixteen, buffers are 2N bytes long
* (@len = 2N) and hold N sixteen bit words in CPU byte order.
*
* When the word size of the SPI transfer is not a power-of-two multiple
* of eight bits, those in-memory words include extra bits. In-memory
* words are always seen by protocol drivers as right-justified, so the
* undefined (rx) or unused (tx) bits are always the most significant bits.
*
* All SPI transfers start with the relevant chipselect active. Normally
* it stays selected until after the last transfer in a message. Drivers
* can affect the chipselect signal using cs_change.
*
* (i) If the transfer isn't the last one in the message, this flag is
* used to make the chipselect briefly go inactive in the middle of the
* message. Toggling chipselect in this way may be needed to terminate
* a chip command, letting a single spi_message perform all of group of
* chip transactions together.
*
* (ii) When the transfer is the last one in the message, the chip may
* stay selected until the next transfer. On multi-device SPI busses
* with nothing blocking messages going to other devices, this is just
* a performance hint; starting a message to another device deselects
* this one. But in other cases, this can be used to ensure correctness.
* Some devices need protocol transactions to be built from a series of
* spi_message submissions, where the content of one message is determined
* by the results of previous messages and where the whole transaction
* ends when the chipselect goes intactive.
*
* The code that submits an spi_message (and its spi_transfers)
* to the lower layers is responsible for managing its memory.
* Zero-initialize every field you don't set up explicitly, to
* insulate against future API updates. After you submit a message
* and its transfers, ignore them until its completion callback.
*/
struct spi_transfer {
/* it's ok if tx_buf == rx_buf (right?)
* for MicroWire, one buffer must be null
* buffers must work with dma_*map_single() calls, unless
* spi_message.is_dma_mapped reports a pre-existing mapping
*/
const void *tx_buf;
void *rx_buf;
unsigned len;
dma_addr_t tx_dma;
dma_addr_t rx_dma;
unsigned cs_change:1;
u8 bits_per_word;
u16 delay_usecs;
u32 speed_hz;
struct list_head transfer_list;
};
/**
* struct spi_message - one multi-segment SPI transaction
* @transfers: list of transfer segments in this transaction
* @spi: SPI device to which the transaction is queued
* @is_dma_mapped: if true, the caller provided both dma and cpu virtual
* addresses for each transfer buffer
* @complete: called to report transaction completions
* @context: the argument to complete() when it's called
* @actual_length: the total number of bytes that were transferred in all
* successful segments
* @status: zero for success, else negative errno
* @queue: for use by whichever driver currently owns the message
* @state: for use by whichever driver currently owns the message
*
* A @spi_message is used to execute an atomic sequence of data transfers,
* each represented by a struct spi_transfer. The sequence is "atomic"
* in the sense that no other spi_message may use that SPI bus until that
* sequence completes. On some systems, many such sequences can execute as
* as single programmed DMA transfer. On all systems, these messages are
* queued, and might complete after transactions to other devices. Messages
* sent to a given spi_device are alway executed in FIFO order.
*
* The code that submits an spi_message (and its spi_transfers)
* to the lower layers is responsible for managing its memory.
* Zero-initialize every field you don't set up explicitly, to
* insulate against future API updates. After you submit a message
* and its transfers, ignore them until its completion callback.
*/
struct spi_message {
struct list_head transfers;
struct spi_device *spi;
unsigned is_dma_mapped:1;
/* REVISIT: we might want a flag affecting the behavior of the
* last transfer ... allowing things like "read 16 bit length L"
* immediately followed by "read L bytes". Basically imposing
* a specific message scheduling algorithm.
*
* Some controller drivers (message-at-a-time queue processing)
* could provide that as their default scheduling algorithm. But
* others (with multi-message pipelines) could need a flag to
* tell them about such special cases.
*/
/* completion is reported through a callback */
void (*complete)(void *context);
void *context;
unsigned actual_length;
int status;
/* for optional use by whatever driver currently owns the
* spi_message ... between calls to spi_async and then later
* complete(), that's the spi_master controller driver.
*/
struct list_head queue;
void *state;
};
static inline void spi_message_init(struct spi_message *m)
{
memset(m, 0, sizeof *m);
INIT_LIST_HEAD(&m->transfers);
}
static inline void
spi_message_add_tail(struct spi_transfer *t, struct spi_message *m)
{
list_add_tail(&t->transfer_list, &m->transfers);
}
static inline void
spi_transfer_del(struct spi_transfer *t)
{
list_del(&t->transfer_list);
}
/* It's fine to embed message and transaction structures in other data
* structures so long as you don't free them while they're in use.
*/
static inline struct spi_message *spi_message_alloc(unsigned ntrans, gfp_t flags)
{
struct spi_message *m;
m = kzalloc(sizeof(struct spi_message)
+ ntrans * sizeof(struct spi_transfer),
flags);
if (m) {
unsigned i;
struct spi_transfer *t = (struct spi_transfer *)(m + 1);
INIT_LIST_HEAD(&m->transfers);
for (i = 0; i < ntrans; i++, t++)
spi_message_add_tail(t, m);
}
return m;
}
static inline void spi_message_free(struct spi_message *m)
{
kfree(m);
}
extern int spi_setup(struct spi_device *spi);
extern int spi_async(struct spi_device *spi, struct spi_message *message);
extern int spi_async_locked(struct spi_device *spi,
struct spi_message *message);
/*---------------------------------------------------------------------------*/
/* All these synchronous SPI transfer routines are utilities layered
* over the core async transfer primitive. Here, "synchronous" means
* they will sleep uninterruptibly until the async transfer completes.
*/
extern int spi_sync(struct spi_device *spi, struct spi_message *message);
extern int spi_sync_locked(struct spi_device *spi, struct spi_message *message);
extern int spi_bus_lock(struct spi_master *master);
extern int spi_bus_unlock(struct spi_master *master);
/**
* spi_write - SPI synchronous write
* @spi: device to which data will be written
* @buf: data buffer
* @len: data buffer size
* Context: can sleep
*
* This writes the buffer and returns zero or a negative error code.
* Callable only from contexts that can sleep.
*/
static inline int
spi_write(struct spi_device *spi, const void *buf, size_t len)
{
struct spi_transfer t = {
.tx_buf = buf,
.len = len,
};
struct spi_message m;
spi_message_init(&m);
spi_message_add_tail(&t, &m);
return spi_sync(spi, &m);
}
/**
* spi_read - SPI synchronous read
* @spi: device from which data will be read
* @buf: data buffer
* @len: data buffer size
* Context: can sleep
*
* This reads the buffer and returns zero or a negative error code.
* Callable only from contexts that can sleep.
*/
static inline int
spi_read(struct spi_device *spi, void *buf, size_t len)
{
struct spi_transfer t = {
.rx_buf = buf,
.len = len,
};
struct spi_message m;
spi_message_init(&m);
spi_message_add_tail(&t, &m);
return spi_sync(spi, &m);
}
/* this copies txbuf and rxbuf data; for small transfers only! */
extern int spi_write_then_read(struct spi_device *spi,
const void *txbuf, unsigned n_tx,
void *rxbuf, unsigned n_rx);
/**
* spi_w8r8 - SPI synchronous 8 bit write followed by 8 bit read
* @spi: device with which data will be exchanged
* @cmd: command to be written before data is read back
* Context: can sleep
*
* This returns the (unsigned) eight bit number returned by the
* device, or else a negative error code. Callable only from
* contexts that can sleep.
*/
static inline ssize_t spi_w8r8(struct spi_device *spi, u8 cmd)
{
ssize_t status;
u8 result;
status = spi_write_then_read(spi, &cmd, 1, &result, 1);
/* return negative errno or unsigned value */
return (status < 0) ? status : result;
}
/**
* spi_w8r16 - SPI synchronous 8 bit write followed by 16 bit read
* @spi: device with which data will be exchanged
* @cmd: command to be written before data is read back
* Context: can sleep
*
* This returns the (unsigned) sixteen bit number returned by the
* device, or else a negative error code. Callable only from
* contexts that can sleep.
*
* The number is returned in wire-order, which is at least sometimes
* big-endian.
*/
static inline ssize_t spi_w8r16(struct spi_device *spi, u8 cmd)
{
ssize_t status;
u16 result;
status = spi_write_then_read(spi, &cmd, 1, (u8 *) &result, 2);
/* return negative errno or unsigned value */
return (status < 0) ? status : result;
}
/*---------------------------------------------------------------------------*/
/*
* INTERFACE between board init code and SPI infrastructure.
*
* No SPI driver ever sees these SPI device table segments, but
* it's how the SPI core (or adapters that get hotplugged) grows
* the driver model tree.
*
* As a rule, SPI devices can't be probed. Instead, board init code
* provides a table listing the devices which are present, with enough
* information to bind and set up the device's driver. There's basic
* support for nonstatic configurations too; enough to handle adding
* parport adapters, or microcontrollers acting as USB-to-SPI bridges.
*/
/**
* struct spi_board_info - board-specific template for a SPI device
* @modalias: Initializes spi_device.modalias; identifies the driver.
* @platform_data: Initializes spi_device.platform_data; the particular
* data stored there is driver-specific.
* @controller_data: Initializes spi_device.controller_data; some
* controllers need hints about hardware setup, e.g. for DMA.
* @irq: Initializes spi_device.irq; depends on how the board is wired.
* @max_speed_hz: Initializes spi_device.max_speed_hz; based on limits
* from the chip datasheet and board-specific signal quality issues.
* @bus_num: Identifies which spi_master parents the spi_device; unused
* by spi_new_device(), and otherwise depends on board wiring.
* @chip_select: Initializes spi_device.chip_select; depends on how
* the board is wired.
* @mode: Initializes spi_device.mode; based on the chip datasheet, board
* wiring (some devices support both 3WIRE and standard modes), and
* possibly presence of an inverter in the chipselect path.
*
* When adding new SPI devices to the device tree, these structures serve
* as a partial device template. They hold information which can't always
* be determined by drivers. Information that probe() can establish (such
* as the default transfer wordsize) is not included here.
*
* These structures are used in two places. Their primary role is to
* be stored in tables of board-specific device descriptors, which are
* declared early in board initialization and then used (much later) to
* populate a controller's device tree after the that controller's driver
* initializes. A secondary (and atypical) role is as a parameter to
* spi_new_device() call, which happens after those controller drivers
* are active in some dynamic board configuration models.
*/
struct spi_board_info {
/* the device name and module name are coupled, like platform_bus;
* "modalias" is normally the driver name.
*
* platform_data goes to spi_device.dev.platform_data,
* controller_data goes to spi_device.controller_data,
* irq is copied too
*/
char modalias[SPI_NAME_SIZE];
const void *platform_data;
void *controller_data;
int irq;
/* slower signaling on noisy or low voltage boards */
u32 max_speed_hz;
/* bus_num is board specific and matches the bus_num of some
* spi_master that will probably be registered later.
*
* chip_select reflects how this chip is wired to that master;
* it's less than num_chipselect.
*/
u16 bus_num;
u16 chip_select;
/* mode becomes spi_device.mode, and is essential for chips
* where the default of SPI_CS_HIGH = 0 is wrong.
*/
u8 mode;
/* ... may need additional spi_device chip config data here.
* avoid stuff protocol drivers can set; but include stuff
* needed to behave without being bound to a driver:
* - quirks like clock rate mattering when not selected
*/
};
#ifdef CONFIG_SPI
extern int
spi_register_board_info(struct spi_board_info const *info, unsigned n);
#else
/* board init code may ignore whether SPI is configured or not */
static inline int
spi_register_board_info(struct spi_board_info const *info, unsigned n)
{ return 0; }
#endif
/* If you're hotplugging an adapter with devices (parport, usb, etc)
* use spi_new_device() to describe each device. You can also call
* spi_unregister_device() to start making that device vanish, but
* normally that would be handled by spi_unregister_master().
*
* You can also use spi_alloc_device() and spi_add_device() to use a two
* stage registration sequence for each spi_device. This gives the caller
* some more control over the spi_device structure before it is registered,
* but requires that caller to initialize fields that would otherwise
* be defined using the board info.
*/
extern struct spi_device *
spi_alloc_device(struct spi_master *master);
extern int
spi_add_device(struct spi_device *spi);
extern struct spi_device *
spi_new_device(struct spi_master *, struct spi_board_info *);
static inline void
spi_unregister_device(struct spi_device *spi)
{
if (spi)
device_unregister(&spi->dev);
}
extern const struct spi_device_id *
spi_get_device_id(const struct spi_device *sdev);
#endif /* __LINUX_SPI_H */
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