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linux-sg2042/drivers/spi/ti-ssp-spi.c

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/*
* Sequencer Serial Port (SSP) based SPI master driver
*
* Copyright (C) 2010 Texas Instruments Inc
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/spi/spi.h>
#include <linux/mfd/ti_ssp.h>
#define MODE_BITS (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH)
struct ti_ssp_spi {
struct spi_master *master;
struct device *dev;
spinlock_t lock;
struct list_head msg_queue;
struct completion complete;
bool shutdown;
struct workqueue_struct *workqueue;
struct work_struct work;
u8 mode, bpw;
int cs_active;
u32 pc_en, pc_dis, pc_wr, pc_rd;
void (*select)(int cs);
};
static u32 ti_ssp_spi_rx(struct ti_ssp_spi *hw)
{
u32 ret;
ti_ssp_run(hw->dev, hw->pc_rd, 0, &ret);
return ret;
}
static void ti_ssp_spi_tx(struct ti_ssp_spi *hw, u32 data)
{
ti_ssp_run(hw->dev, hw->pc_wr, data << (32 - hw->bpw), NULL);
}
static int ti_ssp_spi_txrx(struct ti_ssp_spi *hw, struct spi_message *msg,
struct spi_transfer *t)
{
int count;
if (hw->bpw <= 8) {
u8 *rx = t->rx_buf;
const u8 *tx = t->tx_buf;
for (count = 0; count < t->len; count += 1) {
if (t->tx_buf)
ti_ssp_spi_tx(hw, *tx++);
if (t->rx_buf)
*rx++ = ti_ssp_spi_rx(hw);
}
} else if (hw->bpw <= 16) {
u16 *rx = t->rx_buf;
const u16 *tx = t->tx_buf;
for (count = 0; count < t->len; count += 2) {
if (t->tx_buf)
ti_ssp_spi_tx(hw, *tx++);
if (t->rx_buf)
*rx++ = ti_ssp_spi_rx(hw);
}
} else {
u32 *rx = t->rx_buf;
const u32 *tx = t->tx_buf;
for (count = 0; count < t->len; count += 4) {
if (t->tx_buf)
ti_ssp_spi_tx(hw, *tx++);
if (t->rx_buf)
*rx++ = ti_ssp_spi_rx(hw);
}
}
msg->actual_length += count; /* bytes transferred */
dev_dbg(&msg->spi->dev, "xfer %s%s, %d bytes, %d bpw, count %d%s\n",
t->tx_buf ? "tx" : "", t->rx_buf ? "rx" : "", t->len,
hw->bpw, count, (count < t->len) ? " (under)" : "");
return (count < t->len) ? -EIO : 0; /* left over data */
}
static void ti_ssp_spi_chip_select(struct ti_ssp_spi *hw, int cs_active)
{
cs_active = !!cs_active;
if (cs_active == hw->cs_active)
return;
ti_ssp_run(hw->dev, cs_active ? hw->pc_en : hw->pc_dis, 0, NULL);
hw->cs_active = cs_active;
}
#define __SHIFT_OUT(bits) (SSP_OPCODE_SHIFT | SSP_OUT_MODE | \
cs_en | clk | SSP_COUNT((bits) * 2 - 1))
#define __SHIFT_IN(bits) (SSP_OPCODE_SHIFT | SSP_IN_MODE | \
cs_en | clk | SSP_COUNT((bits) * 2 - 1))
static int ti_ssp_spi_setup_transfer(struct ti_ssp_spi *hw, u8 bpw, u8 mode)
{
int error, idx = 0;
u32 seqram[16];
u32 cs_en, cs_dis, clk;
u32 topbits, botbits;
mode &= MODE_BITS;
if (mode == hw->mode && bpw == hw->bpw)
return 0;
cs_en = (mode & SPI_CS_HIGH) ? SSP_CS_HIGH : SSP_CS_LOW;
cs_dis = (mode & SPI_CS_HIGH) ? SSP_CS_LOW : SSP_CS_HIGH;
clk = (mode & SPI_CPOL) ? SSP_CLK_HIGH : SSP_CLK_LOW;
/* Construct instructions */
/* Disable Chip Select */
hw->pc_dis = idx;
seqram[idx++] = SSP_OPCODE_DIRECT | SSP_OUT_MODE | cs_dis | clk;
seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_dis | clk;
/* Enable Chip Select */
hw->pc_en = idx;
seqram[idx++] = SSP_OPCODE_DIRECT | SSP_OUT_MODE | cs_en | clk;
seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
/* Reads and writes need to be split for bpw > 16 */
topbits = (bpw > 16) ? 16 : bpw;
botbits = bpw - topbits;
/* Write */
hw->pc_wr = idx;
seqram[idx++] = __SHIFT_OUT(topbits) | SSP_ADDR_REG;
if (botbits)
seqram[idx++] = __SHIFT_OUT(botbits) | SSP_DATA_REG;
seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
/* Read */
hw->pc_rd = idx;
if (botbits)
seqram[idx++] = __SHIFT_IN(botbits) | SSP_ADDR_REG;
seqram[idx++] = __SHIFT_IN(topbits) | SSP_DATA_REG;
seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
error = ti_ssp_load(hw->dev, 0, seqram, idx);
if (error < 0)
return error;
error = ti_ssp_set_mode(hw->dev, ((mode & SPI_CPHA) ?
0 : SSP_EARLY_DIN));
if (error < 0)
return error;
hw->bpw = bpw;
hw->mode = mode;
return error;
}
static void ti_ssp_spi_work(struct work_struct *work)
{
struct ti_ssp_spi *hw = container_of(work, struct ti_ssp_spi, work);
spin_lock(&hw->lock);
while (!list_empty(&hw->msg_queue)) {
struct spi_message *m;
struct spi_device *spi;
struct spi_transfer *t = NULL;
int status = 0;
m = container_of(hw->msg_queue.next, struct spi_message,
queue);
list_del_init(&m->queue);
spin_unlock(&hw->lock);
spi = m->spi;
if (hw->select)
hw->select(spi->chip_select);
list_for_each_entry(t, &m->transfers, transfer_list) {
int bpw = spi->bits_per_word;
int xfer_status;
if (t->bits_per_word)
bpw = t->bits_per_word;
if (ti_ssp_spi_setup_transfer(hw, bpw, spi->mode) < 0)
break;
ti_ssp_spi_chip_select(hw, 1);
xfer_status = ti_ssp_spi_txrx(hw, m, t);
if (xfer_status < 0)
status = xfer_status;
if (t->delay_usecs)
udelay(t->delay_usecs);
if (t->cs_change)
ti_ssp_spi_chip_select(hw, 0);
}
ti_ssp_spi_chip_select(hw, 0);
m->status = status;
m->complete(m->context);
spin_lock(&hw->lock);
}
if (hw->shutdown)
complete(&hw->complete);
spin_unlock(&hw->lock);
}
static int ti_ssp_spi_setup(struct spi_device *spi)
{
if (spi->bits_per_word > 32)
return -EINVAL;
return 0;
}
static int ti_ssp_spi_transfer(struct spi_device *spi, struct spi_message *m)
{
struct ti_ssp_spi *hw;
struct spi_transfer *t;
int error = 0;
m->actual_length = 0;
m->status = -EINPROGRESS;
hw = spi_master_get_devdata(spi->master);
if (list_empty(&m->transfers) || !m->complete)
return -EINVAL;
list_for_each_entry(t, &m->transfers, transfer_list) {
if (t->len && !(t->rx_buf || t->tx_buf)) {
dev_err(&spi->dev, "invalid xfer, no buffer\n");
return -EINVAL;
}
if (t->len && t->rx_buf && t->tx_buf) {
dev_err(&spi->dev, "invalid xfer, full duplex\n");
return -EINVAL;
}
if (t->bits_per_word > 32) {
dev_err(&spi->dev, "invalid xfer width %d\n",
t->bits_per_word);
return -EINVAL;
}
}
spin_lock(&hw->lock);
if (hw->shutdown) {
error = -ESHUTDOWN;
goto error_unlock;
}
list_add_tail(&m->queue, &hw->msg_queue);
queue_work(hw->workqueue, &hw->work);
error_unlock:
spin_unlock(&hw->lock);
return error;
}
static int __devinit ti_ssp_spi_probe(struct platform_device *pdev)
{
const struct ti_ssp_spi_data *pdata;
struct ti_ssp_spi *hw;
struct spi_master *master;
struct device *dev = &pdev->dev;
int error = 0;
pdata = dev->platform_data;
if (!pdata) {
dev_err(dev, "platform data not found\n");
return -EINVAL;
}
master = spi_alloc_master(dev, sizeof(struct ti_ssp_spi));
if (!master) {
dev_err(dev, "cannot allocate SPI master\n");
return -ENOMEM;
}
hw = spi_master_get_devdata(master);
platform_set_drvdata(pdev, hw);
hw->master = master;
hw->dev = dev;
hw->select = pdata->select;
spin_lock_init(&hw->lock);
init_completion(&hw->complete);
INIT_LIST_HEAD(&hw->msg_queue);
INIT_WORK(&hw->work, ti_ssp_spi_work);
hw->workqueue = create_singlethread_workqueue(dev_name(dev));
if (!hw->workqueue) {
error = -ENOMEM;
dev_err(dev, "work queue creation failed\n");
goto error_wq;
}
error = ti_ssp_set_iosel(hw->dev, pdata->iosel);
if (error < 0) {
dev_err(dev, "io setup failed\n");
goto error_iosel;
}
master->bus_num = pdev->id;
master->num_chipselect = pdata->num_cs;
master->mode_bits = MODE_BITS;
master->flags = SPI_MASTER_HALF_DUPLEX;
master->setup = ti_ssp_spi_setup;
master->transfer = ti_ssp_spi_transfer;
error = spi_register_master(master);
if (error) {
dev_err(dev, "master registration failed\n");
goto error_reg;
}
return 0;
error_reg:
error_iosel:
destroy_workqueue(hw->workqueue);
error_wq:
spi_master_put(master);
return error;
}
static int __devexit ti_ssp_spi_remove(struct platform_device *pdev)
{
struct ti_ssp_spi *hw = platform_get_drvdata(pdev);
int error;
hw->shutdown = 1;
while (!list_empty(&hw->msg_queue)) {
error = wait_for_completion_interruptible(&hw->complete);
if (error < 0) {
hw->shutdown = 0;
return error;
}
}
destroy_workqueue(hw->workqueue);
spi_unregister_master(hw->master);
return 0;
}
static struct platform_driver ti_ssp_spi_driver = {
.probe = ti_ssp_spi_probe,
.remove = __devexit_p(ti_ssp_spi_remove),
.driver = {
.name = "ti-ssp-spi",
.owner = THIS_MODULE,
},
};
static int __init ti_ssp_spi_init(void)
{
return platform_driver_register(&ti_ssp_spi_driver);
}
module_init(ti_ssp_spi_init);
static void __exit ti_ssp_spi_exit(void)
{
platform_driver_unregister(&ti_ssp_spi_driver);
}
module_exit(ti_ssp_spi_exit);
MODULE_DESCRIPTION("SSP SPI Master");
MODULE_AUTHOR("Cyril Chemparathy");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:ti-ssp-spi");
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