gpio: pca953x: Get platform_data from OpenFirmware

On OpenFirmware platforms, it makes the most sense to get platform_data
from the device tree.  Make an attempt to translate OF node properties
into platform_data struct before bailing out.

Note that the implementation approach taken differs from other device
drivers that make use of device tree information.  This is because I2C
chips are already registered automatically by of_i2c, so we can get by
with a small translator function in the driver.

[[email protected]: coding-style fixes]
[[email protected]: kfree(NULL) is legal]
Signed-off-by: Nate Case <[email protected]>
Cc: David Brownell <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

drivers/gpio/pca953x.c

@@ -15,6 +15,10 @@
 #include <linux/init.h>
 #include <linux/i2c.h>
 #include <linux/i2c/pca953x.h>
+#ifdef CONFIG_OF_GPIO
+#include <linux/of_platform.h>
+#include <linux/of_gpio.h>
+#endif
 
 #include <asm/gpio.h>
 
@@ -49,6 +53,7 @@ struct pca953x_chip {
 	uint16_t reg_direction;
 
 	struct i2c_client *client;
+	struct pca953x_platform_data *dyn_pdata;
 	struct gpio_chip gpio_chip;
 	char **names;
 };
@@ -196,22 +201,80 @@ static void pca953x_setup_gpio(struct pca953x_chip *chip, int gpios)
 	gc->names = chip->names;
 }
 
+/*
+ * Handlers for alternative sources of platform_data
+ */
+#ifdef CONFIG_OF_GPIO
+/*
+ * Translate OpenFirmware node properties into platform_data
+ */
+static struct pca953x_platform_data *
+pca953x_get_alt_pdata(struct i2c_client *client)
+{
+	struct pca953x_platform_data *pdata;
+	struct device_node *node;
+	const uint16_t *val;
+
+	node = dev_archdata_get_node(&client->dev.archdata);
+	if (node == NULL)
+		return NULL;
+
+	pdata = kzalloc(sizeof(struct pca953x_platform_data), GFP_KERNEL);
+	if (pdata == NULL) {
+		dev_err(&client->dev, "Unable to allocate platform_data\n");
+		return NULL;
+	}
+
+	pdata->gpio_base = -1;
+	val = of_get_property(node, "linux,gpio-base", NULL);
+	if (val) {
+		if (*val < 0)
+			dev_warn(&client->dev,
+				 "invalid gpio-base in device tree\n");
+		else
+			pdata->gpio_base = *val;
+	}
+
+	val = of_get_property(node, "polarity", NULL);
+	if (val)
+		pdata->invert = *val;
+
+	return pdata;
+}
+#else
+static struct pca953x_platform_data *
+pca953x_get_alt_pdata(struct i2c_client *client)
+{
+	return NULL;
+}
+#endif
+
 static int __devinit pca953x_probe(struct i2c_client *client,
 				   const struct i2c_device_id *id)
 {
 	struct pca953x_platform_data *pdata;
 	struct pca953x_chip *chip;
 	int ret;
 
+	chip = kzalloc(sizeof(struct pca953x_chip), GFP_KERNEL);
+	if (chip == NULL)
+		return -ENOMEM;
+
 	pdata = client->dev.platform_data;
 	if (pdata == NULL) {
-		dev_dbg(&client->dev, "no platform data\n");
-		return -EINVAL;
+		pdata = pca953x_get_alt_pdata(client);
+		/*
+		 * Unlike normal platform_data, this is allocated
+		 * dynamically and must be freed in the driver
+		 */
+		chip->dyn_pdata = pdata;
 	}
 
-	chip = kzalloc(sizeof(struct pca953x_chip), GFP_KERNEL);
-	if (chip == NULL)
-		return -ENOMEM;
+	if (pdata == NULL) {
+		dev_dbg(&client->dev, "no platform data\n");
+		ret = -EINVAL;
+		goto out_failed;
+	}
 
 	chip->client = client;
 
@@ -253,6 +316,7 @@ static int __devinit pca953x_probe(struct i2c_client *client,
 	return 0;
 
 out_failed:
+	kfree(chip->dyn_pdata);
 	kfree(chip);
 	return ret;
 }
@@ -280,6 +344,7 @@ static int pca953x_remove(struct i2c_client *client)
 		return ret;
 	}
 
+	kfree(chip->dyn_pdata);
 	kfree(chip);
 	return 0;
 }