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>

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);