i2c/gpio: add DT support

To achieve DT support, we need to populate a custom platform_data in a
private struct from DT information. To simplify code, the adapter and
algorithm are also put into the private struct.
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>

Documentation/devicetree/bindings/gpio/gpio_i2c.txt

+Device-Tree bindings for i2c gpio driver
+
+Required properties:
+	- compatible = "i2c-gpio";
+	- gpios: sda and scl gpio
+
+
+Optional properties:
+	- i2c-gpio,sda-open-drain: sda as open drain
+	- i2c-gpio,scl-open-drain: scl as open drain
+	- i2c-gpio,scl-output-only: scl as output only
+	- i2c-gpio,delay-us: delay between GPIO operations (may depend on each platform)
+	- i2c-gpio,timeout-ms: timeout to get data
+
+Example nodes:
+
+i2c@0 {
+	compatible = "i2c-gpio";
+	gpios = <&pioA 23 0 /* sda */
+		 &pioA 24 0 /* scl */
+		>;
+	i2c-gpio,sda-open-drain;
+	i2c-gpio,scl-open-drain;
+	i2c-gpio,delay-us = <2>;	/* ~100 kHz */
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	rv3029c2@56 {
+		compatible = "rv3029c2";
+		reg = <0x56>;
+	};
+};

drivers/i2c/busses/i2c-gpio.c

@@ -14,8 +14,15 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/platform_device.h>
-
-#include <asm/gpio.h>
+#include <linux/gpio.h>
+#include <linux/of_gpio.h>
+#include <linux/of_i2c.h>
+
+struct i2c_gpio_private_data {
+	struct i2c_adapter adap;
+	struct i2c_algo_bit_data bit_data;
+	struct i2c_gpio_platform_data pdata;
+};
 
 /* Toggle SDA by changing the direction of the pin */
 static void i2c_gpio_setsda_dir(void *data, int state)
@@ -78,24 +85,62 @@ static int i2c_gpio_getscl(void *data)
 	return gpio_get_value(pdata->scl_pin);
 }
 
+static int __devinit of_i2c_gpio_probe(struct device_node *np,
+			     struct i2c_gpio_platform_data *pdata)
+{
+	u32 reg;
+
+	if (of_gpio_count(np) < 2)
+		return -ENODEV;
+
+	pdata->sda_pin = of_get_gpio(np, 0);
+	pdata->scl_pin = of_get_gpio(np, 1);
+
+	if (!gpio_is_valid(pdata->sda_pin) || !gpio_is_valid(pdata->scl_pin)) {
+		pr_err("%s: invalid GPIO pins, sda=%d/scl=%d\n",
+		       np->full_name, pdata->sda_pin, pdata->scl_pin);
+		return -ENODEV;
+	}
+
+	of_property_read_u32(np, "i2c-gpio,delay-us", &pdata->udelay);
+
+	if (!of_property_read_u32(np, "i2c-gpio,timeout-ms", &reg))
+		pdata->timeout = msecs_to_jiffies(reg);
+
+	pdata->sda_is_open_drain =
+		of_property_read_bool(np, "i2c-gpio,sda-open-drain");
+	pdata->scl_is_open_drain =
+		of_property_read_bool(np, "i2c-gpio,scl-open-drain");
+	pdata->scl_is_output_only =
+		of_property_read_bool(np, "i2c-gpio,scl-output-only");
+
+	return 0;
+}
+
 static int __devinit i2c_gpio_probe(struct platform_device *pdev)
 {
+	struct i2c_gpio_private_data *priv;
 	struct i2c_gpio_platform_data *pdata;
 	struct i2c_algo_bit_data *bit_data;
 	struct i2c_adapter *adap;
 	int ret;
 
-	pdata = pdev->dev.platform_data;
-	if (!pdata)
-		return -ENXIO;
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+	adap = &priv->adap;
+	bit_data = &priv->bit_data;
+	pdata = &priv->pdata;
 
-	ret = -ENOMEM;
-	adap = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL);
-	if (!adap)
-		goto err_alloc_adap;
-	bit_data = kzalloc(sizeof(struct i2c_algo_bit_data), GFP_KERNEL);
-	if (!bit_data)
-		goto err_alloc_bit_data;
+	if (pdev->dev.of_node) {
+		ret = of_i2c_gpio_probe(pdev->dev.of_node, pdata);
+		if (ret)
+			return ret;
+	} else {
+		if (!pdev->dev.platform_data)
+			return -ENXIO;
+		memcpy(pdata, pdev->dev.platform_data, sizeof(*pdata));
+	}
 
 	ret = gpio_request(pdata->sda_pin, "sda");
 	if (ret)
@@ -143,6 +188,7 @@ static int __devinit i2c_gpio_probe(struct platform_device *pdev)
 	adap->algo_data = bit_data;
 	adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
 	adap->dev.parent = &pdev->dev;
+	adap->dev.of_node = pdev->dev.of_node;
 
 	/*
 	 * If "dev->id" is negative we consider it as zero.
@@ -154,7 +200,9 @@ static int __devinit i2c_gpio_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_add_bus;
 
-	platform_set_drvdata(pdev, adap);
+	of_i2c_register_devices(adap);
+
+	platform_set_drvdata(pdev, priv);
 
 	dev_info(&pdev->dev, "using pins %u (SDA) and %u (SCL%s)\n",
 		 pdata->sda_pin, pdata->scl_pin,
@@ -168,34 +216,40 @@ static int __devinit i2c_gpio_probe(struct platform_device *pdev)
 err_request_scl:
 	gpio_free(pdata->sda_pin);
 err_request_sda:
-	kfree(bit_data);
-err_alloc_bit_data:
-	kfree(adap);
-err_alloc_adap:
 	return ret;
 }
 
 static int __devexit i2c_gpio_remove(struct platform_device *pdev)
 {
+	struct i2c_gpio_private_data *priv;
 	struct i2c_gpio_platform_data *pdata;
 	struct i2c_adapter *adap;
 
-	adap = platform_get_drvdata(pdev);
-	pdata = pdev->dev.platform_data;
+	priv = platform_get_drvdata(pdev);
+	adap = &priv->adap;
+	pdata = &priv->pdata;
 
 	i2c_del_adapter(adap);
 	gpio_free(pdata->scl_pin);
 	gpio_free(pdata->sda_pin);
-	kfree(adap->algo_data);
-	kfree(adap);
 
 	return 0;
 }
 
+#if defined(CONFIG_OF)
+static const struct of_device_id i2c_gpio_dt_ids[] = {
+	{ .compatible = "i2c-gpio", },
+	{ /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, i2c_gpio_dt_ids);
+#endif
+
 static struct platform_driver i2c_gpio_driver = {
 	.driver		= {
 		.name	= "i2c-gpio",
 		.owner	= THIS_MODULE,
+		.of_match_table	= of_match_ptr(i2c_gpio_dt_ids),
 	},
 	.probe		= i2c_gpio_probe,
 	.remove		= __devexit_p(i2c_gpio_remove),