gpio: pcf857x: add lock and handle more chips

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 <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 9e0c4fbfc51ab6974dac6e01c898a86a12e448d8..fced1909cbba0dd055c2a01cd73fc5303138750b 100644 (file)
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -45,7 +45,7 @@ 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
@@ -54,7 +54,8 @@ 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

diff --git a/drivers/gpio/pcf857x.c b/drivers/gpio/pcf857x.c
index aa6cc8b2a2bc88afbeca4dec1b67bc75c05288a0..d25d356c4f200c9a197a5ac84373f7441e415e3a 100644 (file)
--- a/drivers/gpio/pcf857x.c
+++ b/drivers/gpio/pcf857x.c
@@ -37,6 +37,8 @@ static const struct i2c_device_id pcf857x_id[] = {
        { "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_chip *chip, unsigned offset, int value)
 {
        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_client *client)
 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_chip *chip, unsigned offset, int value)
 {
        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_client *client,
        if (!gpio)
                return -ENOMEM;
 
+       mutex_init(&gpio->lock);
+
        gpio->chip.base = pdata->gpio_base;
        gpio->chip.can_sleep = 1;
        gpio->chip.owner = THIS_MODULE;