Add support for TCA6424A

This patch extends the PCA953x driver to support TI's TCA6424A 24 bit I2C I/O expander. The patch is based on code by Michele
Bevilacqua.

Changes in v2:
- Compare ngpio against 24 in both places, not >16
- Larger datatype now u32 instead of uint.
  Bit fields not used for struct members since their address is taken.
- Be precise: TCA6424A (untested for older TCA6424)

Signed-off-by: Andreas Schallenberg<Andreas.Schallenberg@3alitytechnica.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

1 files changed, 30 insertions, 13 deletions

diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index d3f3e8f5456..1c313c710be 100644
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -28,6 +28,8 @@
 #define PCA953X_INVERT          2
 #define PCA953X_DIRECTION       3
 
+#define REG_ADDR_AI             0x80
+
 #define PCA957X_IN              0
 #define PCA957X_INVRT           1
 #define PCA957X_BKEN            2
@@ -63,15 +65,15 @@ static const struct i2c_device_id pca953x_id[] = {
         { "pca6107", 8  | PCA953X_TYPE | PCA_INT, },
         { "tca6408", 8  | PCA953X_TYPE | PCA_INT, },
         { "tca6416", 16 | PCA953X_TYPE | PCA_INT, },
-        /* NYET:  { "tca6424", 24, }, */
+        { "tca6424", 24 | PCA953X_TYPE | PCA_INT, },
         { }
 };
 MODULE_DEVICE_TABLE(i2c, pca953x_id);
 
 struct pca953x_chip {
         unsigned gpio_start;
-        uint16_t reg_output;
-        uint16_t reg_direction;
+        u32 reg_output;
+        u32 reg_direction;
         struct mutex i2c_lock;
 
 #ifdef CONFIG_GPIO_PCA953X_IRQ
@@ -89,12 +91,20 @@ struct pca953x_chip {
         int     chip_type;
 };
 
-static int pca953x_write_reg(struct pca953x_chip *chip, int reg, uint16_t val)
+static int pca953x_write_reg(struct pca953x_chip *chip, int reg, u32 val)
 {
         int ret = 0;
 
         if (chip->gpio_chip.ngpio <= 8)
                 ret = i2c_smbus_write_byte_data(chip->client, reg, val);
+        else if (chip->gpio_chip.ngpio == 24) {
+                ret = i2c_smbus_write_word_data(chip->client,
+                                                (reg << 2) | REG_ADDR_AI,
+                                                val & 0xffff);
+                ret = i2c_smbus_write_byte_data(chip->client,
+                                                (reg << 2) + 2,
+                                                (val & 0xff0000) >> 16);
+        }
         else {
                 switch (chip->chip_type) {
                 case PCA953X_TYPE:
@@ -121,12 +131,17 @@ static int pca953x_write_reg(struct pca953x_chip *chip, int reg, uint16_t val)
         return 0;
 }
 
-static int pca953x_read_reg(struct pca953x_chip *chip, int reg, uint16_t *val)
+static int pca953x_read_reg(struct pca953x_chip *chip, int reg, u32 *val)
 {
         int ret;
 
         if (chip->gpio_chip.ngpio <= 8)
                 ret = i2c_smbus_read_byte_data(chip->client, reg);
+        else if (chip->gpio_chip.ngpio == 24) {
+                ret =  i2c_smbus_read_word_data(chip->client, reg << 2);
+                ret |= (i2c_smbus_read_byte_data(chip->client,
+                                                 (reg << 2) + 2)<<16);
+        }
         else
                 ret = i2c_smbus_read_word_data(chip->client, reg << 1);
 
@@ -135,14 +150,14 @@ static int pca953x_read_reg(struct pca953x_chip *chip, int reg, uint16_t *val)
                 return ret;
         }
 
-        *val = (uint16_t)ret;
+        *val = (u32)ret;
         return 0;
 }
 
 static int pca953x_gpio_direction_input(struct gpio_chip *gc, unsigned off)
 {
         struct pca953x_chip *chip;
-        uint16_t reg_val;
+        uint reg_val;
         int ret, offset = 0;
 
         chip = container_of(gc, struct pca953x_chip, gpio_chip);
@@ -173,7 +188,7 @@ static int pca953x_gpio_direction_output(struct gpio_chip *gc,
                 unsigned off, int val)
 {
         struct pca953x_chip *chip;
-        uint16_t reg_val;
+        uint reg_val;
         int ret, offset = 0;
 
         chip = container_of(gc, struct pca953x_chip, gpio_chip);
@@ -223,7 +238,7 @@ exit:
 static int pca953x_gpio_get_value(struct gpio_chip *gc, unsigned off)
 {
         struct pca953x_chip *chip;
-        uint16_t reg_val;
+        u32 reg_val;
         int ret, offset = 0;
 
         chip = container_of(gc, struct pca953x_chip, gpio_chip);
@@ -253,7 +268,7 @@ static int pca953x_gpio_get_value(struct gpio_chip *gc, unsigned off)
 static void pca953x_gpio_set_value(struct gpio_chip *gc, unsigned off, int val)
 {
         struct pca953x_chip *chip;
-        uint16_t reg_val;
+        u32 reg_val;
         int ret, offset = 0;
 
         chip = container_of(gc, struct pca953x_chip, gpio_chip);
@@ -386,7 +401,7 @@ static struct irq_chip pca953x_irq_chip = {
 
 static uint16_t pca953x_irq_pending(struct pca953x_chip *chip)
 {
-        uint16_t cur_stat;
+        u32 cur_stat;
         uint16_t old_stat;
         uint16_t pending;
         uint16_t trigger;
@@ -449,6 +464,7 @@ static int pca953x_irq_setup(struct pca953x_chip *chip,
 {
         struct i2c_client *client = chip->client;
         int ret, offset = 0;
+        u32 temporary;
 
         if (irq_base != -1
                         && (id->driver_data & PCA_INT)) {
@@ -462,7 +478,8 @@ static int pca953x_irq_setup(struct pca953x_chip *chip,
                         offset = PCA957X_IN;
                         break;
                 }
-                ret = pca953x_read_reg(chip, offset, &chip->irq_stat);
+                ret = pca953x_read_reg(chip, offset, &temporary);
+                chip->irq_stat = temporary;
                 if (ret)
                         goto out_failed;
 
@@ -603,7 +620,7 @@ out:
 static int __devinit device_pca957x_init(struct pca953x_chip *chip, int invert)
 {
         int ret;
-        uint16_t val = 0;
+        u32 val = 0;
 
         /* Let every port in proper state, that could save power */
         pca953x_write_reg(chip, PCA957X_PUPD, 0x0);