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linux/drivers/gpio/mcp23s08.c

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/*
* mcp23s08.c - SPI gpio expander driver
*/
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/workqueue.h>
#include <linux/mutex.h>
#include <linux/spi/spi.h>
#include <linux/spi/mcp23s08.h>
#include <asm/gpio.h>
/* Registers are all 8 bits wide.
*
* The mcp23s17 has twice as many bits, and can be configured to work
* with either 16 bit registers or with two adjacent 8 bit banks.
*
* Also, there are I2C versions of both chips.
*/
#define MCP_IODIR 0x00 /* init/reset: all ones */
#define MCP_IPOL 0x01
#define MCP_GPINTEN 0x02
#define MCP_DEFVAL 0x03
#define MCP_INTCON 0x04
#define MCP_IOCON 0x05
# define IOCON_SEQOP (1 << 5)
# define IOCON_HAEN (1 << 3)
# define IOCON_ODR (1 << 2)
# define IOCON_INTPOL (1 << 1)
#define MCP_GPPU 0x06
#define MCP_INTF 0x07
#define MCP_INTCAP 0x08
#define MCP_GPIO 0x09
#define MCP_OLAT 0x0a
struct mcp23s08 {
struct spi_device *spi;
u8 addr;
/* lock protects the cached values */
struct mutex lock;
u8 cache[11];
struct gpio_chip chip;
struct work_struct work;
};
static int mcp23s08_read(struct mcp23s08 *mcp, unsigned reg)
{
u8 tx[2], rx[1];
int status;
tx[0] = mcp->addr | 0x01;
tx[1] = reg;
status = spi_write_then_read(mcp->spi, tx, sizeof tx, rx, sizeof rx);
return (status < 0) ? status : rx[0];
}
static int mcp23s08_write(struct mcp23s08 *mcp, unsigned reg, u8 val)
{
u8 tx[3];
tx[0] = mcp->addr;
tx[1] = reg;
tx[2] = val;
return spi_write_then_read(mcp->spi, tx, sizeof tx, NULL, 0);
}
static int
mcp23s08_read_regs(struct mcp23s08 *mcp, unsigned reg, u8 *vals, unsigned n)
{
u8 tx[2];
if ((n + reg) > sizeof mcp->cache)
return -EINVAL;
tx[0] = mcp->addr | 0x01;
tx[1] = reg;
return spi_write_then_read(mcp->spi, tx, sizeof tx, vals, n);
}
/*----------------------------------------------------------------------*/
static int mcp23s08_direction_input(struct gpio_chip *chip, unsigned offset)
{
struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
int status;
mutex_lock(&mcp->lock);
mcp->cache[MCP_IODIR] |= (1 << offset);
status = mcp23s08_write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);
mutex_unlock(&mcp->lock);
return status;
}
static int mcp23s08_get(struct gpio_chip *chip, unsigned offset)
{
struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
int status;
mutex_lock(&mcp->lock);
/* REVISIT reading this clears any IRQ ... */
status = mcp23s08_read(mcp, MCP_GPIO);
if (status < 0)
status = 0;
else {
mcp->cache[MCP_GPIO] = status;
status = !!(status & (1 << offset));
}
mutex_unlock(&mcp->lock);
return status;
}
static int __mcp23s08_set(struct mcp23s08 *mcp, unsigned mask, int value)
{
u8 olat = mcp->cache[MCP_OLAT];
if (value)
olat |= mask;
else
olat &= ~mask;
mcp->cache[MCP_OLAT] = olat;
return mcp23s08_write(mcp, MCP_OLAT, olat);
}
static void mcp23s08_set(struct gpio_chip *chip, unsigned offset, int value)
{
struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
u8 mask = 1 << offset;
mutex_lock(&mcp->lock);
__mcp23s08_set(mcp, mask, value);
mutex_unlock(&mcp->lock);
}
static int
mcp23s08_direction_output(struct gpio_chip *chip, unsigned offset, int value)
{
struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
u8 mask = 1 << offset;
int status;
mutex_lock(&mcp->lock);
status = __mcp23s08_set(mcp, mask, value);
if (status == 0) {
mcp->cache[MCP_IODIR] &= ~mask;
status = mcp23s08_write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);
}
mutex_unlock(&mcp->lock);
return status;
}
/*----------------------------------------------------------------------*/
#ifdef CONFIG_DEBUG_FS
#include <linux/seq_file.h>
/*
* This shows more info than the generic gpio dump code:
* pullups, deglitching, open drain drive.
*/
static void mcp23s08_dbg_show(struct seq_file *s, struct gpio_chip *chip)
{
struct mcp23s08 *mcp;
char bank;
unsigned t;
unsigned mask;
mcp = container_of(chip, struct mcp23s08, chip);
/* NOTE: we only handle one bank for now ... */
bank = '0' + ((mcp->addr >> 1) & 0x3);
mutex_lock(&mcp->lock);
t = mcp23s08_read_regs(mcp, 0, mcp->cache, sizeof mcp->cache);
if (t < 0) {
seq_printf(s, " I/O ERROR %d\n", t);
goto done;
}
for (t = 0, mask = 1; t < 8; t++, mask <<= 1) {
const char *label;
label = gpiochip_is_requested(chip, t);
if (!label)
continue;
seq_printf(s, " gpio-%-3d P%c.%d (%-12s) %s %s %s",
chip->base + t, bank, t, label,
(mcp->cache[MCP_IODIR] & mask) ? "in " : "out",
(mcp->cache[MCP_GPIO] & mask) ? "hi" : "lo",
(mcp->cache[MCP_GPPU] & mask) ? " " : "up");
/* NOTE: ignoring the irq-related registers */
seq_printf(s, "\n");
}
done:
mutex_unlock(&mcp->lock);
}
#else
#define mcp23s08_dbg_show NULL
#endif
/*----------------------------------------------------------------------*/
static int mcp23s08_probe(struct spi_device *spi)
{
struct mcp23s08 *mcp;
struct mcp23s08_platform_data *pdata;
int status;
int do_update = 0;
pdata = spi->dev.platform_data;
if (!pdata || pdata->slave > 3 || !pdata->base)
return -ENODEV;
mcp = kzalloc(sizeof *mcp, GFP_KERNEL);
if (!mcp)
return -ENOMEM;
mutex_init(&mcp->lock);
mcp->spi = spi;
mcp->addr = 0x40 | (pdata->slave << 1);
mcp->chip.label = "mcp23s08",
mcp->chip.direction_input = mcp23s08_direction_input;
mcp->chip.get = mcp23s08_get;
mcp->chip.direction_output = mcp23s08_direction_output;
mcp->chip.set = mcp23s08_set;
mcp->chip.dbg_show = mcp23s08_dbg_show;
mcp->chip.base = pdata->base;
mcp->chip.ngpio = 8;
mcp->chip.can_sleep = 1;
spi_set_drvdata(spi, mcp);
/* verify MCP_IOCON.SEQOP = 0, so sequential reads work */
status = mcp23s08_read(mcp, MCP_IOCON);
if (status < 0)
goto fail;
if (status & IOCON_SEQOP) {
status &= ~IOCON_SEQOP;
status = mcp23s08_write(mcp, MCP_IOCON, (u8) status);
if (status < 0)
goto fail;
}
/* configure ~100K pullups */
status = mcp23s08_write(mcp, MCP_GPPU, pdata->pullups);
if (status < 0)
goto fail;
status = mcp23s08_read_regs(mcp, 0, mcp->cache, sizeof mcp->cache);
if (status < 0)
goto fail;
/* disable inverter on input */
if (mcp->cache[MCP_IPOL] != 0) {
mcp->cache[MCP_IPOL] = 0;
do_update = 1;
}
/* disable irqs */
if (mcp->cache[MCP_GPINTEN] != 0) {
mcp->cache[MCP_GPINTEN] = 0;
do_update = 1;
}
if (do_update) {
u8 tx[4];
tx[0] = mcp->addr;
tx[1] = MCP_IPOL;
memcpy(&tx[2], &mcp->cache[MCP_IPOL], sizeof(tx) - 2);
status = spi_write_then_read(mcp->spi, tx, sizeof tx, NULL, 0);
/* FIXME check status... */
}
status = gpiochip_add(&mcp->chip);
/* NOTE: these chips have a relatively sane IRQ framework, with
* per-signal masking and level/edge triggering. It's not yet
* handled here...
*/
if (pdata->setup) {
status = pdata->setup(spi, mcp->chip.base,
mcp->chip.ngpio, pdata->context);
if (status < 0)
dev_dbg(&spi->dev, "setup --> %d\n", status);
}
return 0;
fail:
kfree(mcp);
return status;
}
static int mcp23s08_remove(struct spi_device *spi)
{
struct mcp23s08 *mcp = spi_get_drvdata(spi);
struct mcp23s08_platform_data *pdata = spi->dev.platform_data;
int status = 0;
if (pdata->teardown) {
status = pdata->teardown(spi,
mcp->chip.base, mcp->chip.ngpio,
pdata->context);
if (status < 0) {
dev_err(&spi->dev, "%s --> %d\n", "teardown", status);
return status;
}
}
status = gpiochip_remove(&mcp->chip);
if (status == 0)
kfree(mcp);
else
dev_err(&spi->dev, "%s --> %d\n", "remove", status);
return status;
}
static struct spi_driver mcp23s08_driver = {
.probe = mcp23s08_probe,
.remove = mcp23s08_remove,
.driver = {
.name = "mcp23s08",
.owner = THIS_MODULE,
},
};
/*----------------------------------------------------------------------*/
static int __init mcp23s08_init(void)
{
return spi_register_driver(&mcp23s08_driver);
}
module_init(mcp23s08_init);
static void __exit mcp23s08_exit(void)
{
spi_unregister_driver(&mcp23s08_driver);
}
module_exit(mcp23s08_exit);
MODULE_LICENSE("GPL");
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