From: David Brownell

Two small updates to the pcf857x driver: (a) the max732[89] chips
are also second sources for the pcf8574/a, and (b) add a mutex to
prevent trashing the cached state. Adding the lock is effectively
a bugfix, although it seems unlikely that anyone would have run
into the issue it protects against.

Signed-off-by: David Brownell
---
drivers/gpio/Kconfig | 5 +++--
drivers/gpio/pcf857x.c | 33 +++++++++++++++++++++++++++++----
2 files changed, 32 insertions(+), 6 deletions(-)

--- a/drivers/gpio/Kconfig 2008-07-13 13:42:29.000000000 -0700
+++ b/drivers/gpio/Kconfig 2008-07-13 14:25:55.000000000 -0700
@@ -79,7 +79,7 @@ config GPIO_PCA953X
will be called pca953x.

config GPIO_PCF857X
- tristate "PCF857x, PCA857x, and PCA967x I2C GPIO expanders"
+ tristate "PCF857x, PCA{85,96}7x, and MAX732[89] I2C GPIO expanders"
depends on I2C
help
Say yes here to provide access to most "quasi-bidirectional" I2C
@@ -88,7 +88,8 @@ config GPIO_PCF857X
some of them. Compatible models include:

8 bits: pcf8574, pcf8574a, pca8574, pca8574a,
- pca9670, pca9672, pca9674, pca9674a
+ pca9670, pca9672, pca9674, pca9674a,
+ max7328, max7329

16 bits: pcf8575, pcf8575c, pca8575,
pca9671, pca9673, pca9675
--- a/drivers/gpio/pcf857x.c 2008-07-13 13:41:36.000000000 -0700
+++ b/drivers/gpio/pcf857x.c 2008-07-13 13:54:06.000000000 -0700
@@ -37,6 +37,8 @@ static const struct i2c_device_id pcf857
{ "pca9671", 16 },
{ "pca9673", 16 },
{ "pca9675", 16 },
+ { "max7328", 8 },
+ { "max7329", 8 },
{ }
};
MODULE_DEVICE_TABLE(i2c, pcf857x_id);
@@ -56,6 +58,7 @@ MODULE_DEVICE_TABLE(i2c, pcf857x_id);
struct pcf857x {
struct gpio_chip chip;
struct i2c_client *client;
+ struct mutex lock; /* protect 'out' */
unsigned out; /* software latch */
};

@@ -66,9 +69,14 @@ struct pcf857x {
static int pcf857x_input8(struct gpio_chip *chip, unsigned offset)
{
struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
+ int status;

+ mutex_lock(&gpio->lock);
gpio->out |= (1 << offset);
- return i2c_smbus_write_byte(gpio->client, gpio->out);
+ status = i2c_smbus_write_byte(gpio->client, gpio->out);
+ mutex_unlock(&gpio->lock);
+
+ return status;
}

static int pcf857x_get8(struct gpio_chip *chip, unsigned offset)
@@ -84,12 +92,17 @@ static int pcf857x_output8(struct gpio_c
{
struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
unsigned bit = 1 << offset;
+ int status;

+ mutex_lock(&gpio->lock);
if (value)
gpio->out |= bit;
else
gpio->out &= ~bit;
- return i2c_smbus_write_byte(gpio->client, gpio->out);
+ status = i2c_smbus_write_byte(gpio->client, gpio->out);
+ mutex_unlock(&gpio->lock);
+
+ return status;
}

static void pcf857x_set8(struct gpio_chip *chip, unsigned offset, int value)
@@ -124,9 +137,14 @@ static int i2c_read_le16(struct i2c_clie
static int pcf857x_input16(struct gpio_chip *chip, unsigned offset)
{
struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
+ int status;

+ mutex_lock(&gpio->lock);
gpio->out |= (1 << offset);
- return i2c_write_le16(gpio->client, gpio->out);
+ status = i2c_write_le16(gpio->client, gpio->out);
+ mutex_unlock(&gpio->lock);
+
+ return status;
}

static int pcf857x_get16(struct gpio_chip *chip, unsigned offset)
@@ -142,12 +160,17 @@ static int pcf857x_output16(struct gpio_
{
struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
unsigned bit = 1 << offset;
+ int status;

+ mutex_lock(&gpio->lock);
if (value)
gpio->out |= bit;
else
gpio->out &= ~bit;
- return i2c_write_le16(gpio->client, gpio->out);
+ status = i2c_write_le16(gpio->client, gpio->out);
+ mutex_unlock(&gpio->lock);
+
+ return status;
}

static void pcf857x_set16(struct gpio_chip *chip, unsigned offset, int value)
@@ -173,6 +196,8 @@ static int pcf857x_probe(struct i2c_clie
if (!gpio)
return -ENOMEM;

+ mutex_init(&gpio->lock);
+
gpio->chip.base = pdata->gpio_base;
gpio->chip.can_sleep = 1;
gpio->chip.dev = &client->dev;
--
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