gpio: handle pca953{4,5,6,7,8} too

This third part of an extension to support more pca953x chips updates the
logic to handle the smaller register widths used by the 4-bit and 8-bit parts,
and to use the chip type to determine how many GPIOs it provides.

As long as we don't support interrupt and reset capabilities, those size
issues are the only software-visible differences between these parts.

Signed-off-by: Guennadi Liakhovetski <[e-mail]>
Signed-off-by: David Brownell <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/gpio/pca953x.c

···
 /*
- *  pca953x.c - 16-bit I/O port with interrupt and reset
+ *  pca953x.c - 4/8/16 bit I/O ports
  *
  *  Copyright (C) 2005 Ben Gardner <[e-mail]>
  *  Copyright (C) 2007 Marvell International Ltd.
···
 
 #include <asm/gpio.h>
 
+#define PCA953X_INPUT          0
+#define PCA953X_OUTPUT         1
+#define PCA953X_INVERT         2
+#define PCA953X_DIRECTION      3
 
-#define NR_PCA953X_GPIOS	16
+/* This is temporary - in 2.6.26 i2c_driver_data should replace it. */
+struct pca953x_desc {
+	char		name[I2C_NAME_SIZE];
+	unsigned long	driver_data;
+};
 
-#define PCA953X_INPUT		0
-#define PCA953X_OUTPUT		2
-#define PCA953X_INVERT		4
-#define PCA953X_DIRECTION	6
+static const struct pca953x_desc pca953x_descs[] = {
+	{ "pca9534", 8, },
+	{ "pca9535", 16, },
+	{ "pca9536", 4, },
+	{ "pca9537", 4, },
+	{ "pca9538", 8, },
+	{ "pca9539", 16, },
+	/* REVISIT several pca955x parts should work here too */
+};
 
 struct pca953x_chip {
 	unsigned gpio_start;
···
  */
 static int pca953x_write_reg(struct pca953x_chip *chip, int reg, uint16_t val)
 {
-	if (i2c_smbus_write_word_data(chip->client, reg, val) < 0)
-		return -EIO;
+	int ret;
+
+	if (chip->gpio_chip.ngpio <= 8)
+		ret = i2c_smbus_write_byte_data(chip->client, reg, val);
 	else
-		return 0;
+		ret = i2c_smbus_write_word_data(chip->client, reg << 1, val);
+
+	if (ret < 0) {
+		dev_err(&chip->client->dev, "failed writing register\n");
+		return -EIO;
+	}
+
+	return 0;
 }
 
 static int pca953x_read_reg(struct pca953x_chip *chip, int reg, uint16_t *val)
 {
 	int ret;
 
-	ret = i2c_smbus_read_word_data(chip->client, reg);
+	if (chip->gpio_chip.ngpio <= 8)
+		ret = i2c_smbus_read_byte_data(chip->client, reg);
+	else
+		ret = i2c_smbus_read_word_data(chip->client, reg << 1);
+
 	if (ret < 0) {
 		dev_err(&chip->client->dev, "failed reading register\n");
 		return -EIO;
···
 	chip->reg_output = reg_val;
 }
 
-static int pca953x_init_gpio(struct pca953x_chip *chip)
+static void pca953x_setup_gpio(struct pca953x_chip *chip, int gpios)
 {
 	struct gpio_chip *gc;
 
···
 	gc->set = pca953x_gpio_set_value;
 
 	gc->base = chip->gpio_start;
-	gc->ngpio = NR_PCA953X_GPIOS;
-	gc->label = "pca953x";
-
-	return gpiochip_add(gc);
+	gc->ngpio = gpios;
+	gc->label = chip->client->name;
 }
 
 static int __devinit pca953x_probe(struct i2c_client *client)
 {
 	struct pca953x_platform_data *pdata;
 	struct pca953x_chip *chip;
-	int ret;
+	int ret, i;
+	const struct pca953x_desc *id = NULL;
 
 	pdata = client->dev.platform_data;
 	if (pdata == NULL)
+		return -ENODEV;
+
+	/* this loop vanishes when we get i2c_device_id */
+	for (i = 0; i < ARRAY_SIZE(pca953x_descs); i++)
+		if (!strcmp(pca953x_descs[i].name, client->name)) {
+			id = pca953x_descs + i;
+			break;
+		}
+	if (!id)
 		return -ENODEV;
 
 	chip = kzalloc(sizeof(struct pca953x_chip), GFP_KERNEL);
···
 	/* initialize cached registers from their original values.
 	 * we can't share this chip with another i2c master.
 	 */
+	pca953x_setup_gpio(chip, id->driver_data);
+
 	ret = pca953x_read_reg(chip, PCA953X_OUTPUT, &chip->reg_output);
 	if (ret)
 		goto out_failed;
···
 	if (ret)
 		goto out_failed;
 
-	ret = pca953x_init_gpio(chip);
+
+	ret = gpiochip_add(&chip->gpio_chip);
 	if (ret)
 		goto out_failed;