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Subject[PATCH v5] i2c-gpio: add devicetree support
Date
From: Albert Herranz <albert_herranz@yahoo.es>

This patch adds devicetree support to i2c-gpio driver. The allocation
of local data is integrated to a private structure, and use devm_*
helper for easy cleanup.

It is base on an earlier patch for gc-linux from
Albert Herranz <albert_herranz@yahoo.es>.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
CC: Albert Herranz <albert_herranz@yahoo.es>
Acked-by: Haavard Skinnemoen <hskinnemoen@gmail.com>
---
for v2.6.39
v2 move of nodes probing to a hook, which will be optimized out
when devicetree is not used.
use linux/gpio.h.
move binding doc to i2c/i2c-gpio.txt.
v3 use speed-hz instead of udelay in dts binding.
condition the devicetree probe.
v4 simplify private allocation.
v5 condition module device table export for of.
Documentation/devicetree/bindings/i2c/i2c-gpio.txt | 40 +++++++
drivers/i2c/busses/i2c-gpio.c | 113 ++++++++++++++++----
2 files changed, 133 insertions(+), 20 deletions(-)
create mode 100644 Documentation/devicetree/bindings/i2c/i2c-gpio.txt
diff --git a/Documentation/devicetree/bindings/i2c/i2c-gpio.txt b/Documentation/devicetree/bindings/i2c/i2c-gpio.txt
new file mode 100644
index 0000000..38ef4f2
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-gpio.txt
@@ -0,0 +1,40 @@
+GPIO-based I2C
+
+Required properties:
+- compatible : should be "i2c-gpio".
+- gpios : should specify GPIOs used for SDA and SCL lines, in that order.
+Optional properties:
+- sda-is-open-drain : present if SDA gpio is open-drain.
+- scl-is-open-drain : present if SCL gpio is open-drain.
+- scl-is-output-only : present if the output driver for SCL cannot be
+ turned off. this will prevent clock stretching from working.
+- speed-hz : SCL frequency.
+- timeout : clock stretching timeout in milliseconds.
+
+Example:
+
+gpio0: starlet-gpio@0d8000c0 {
+ compatible = "nintendo,starlet-gpio";
+ reg = <0d8000c0 4>;
+ gpio-controller;
+ #gpio-cells = <2>;
+};
+
+i2c-video {
+ #address-cells = <1>;
+ #size-cells = <0>;
+ compatible = "i2c-gpio";
+
+ gpios = <&gpio0 10 0 /* SDA line */
+ &gpio0 11 0 /* SCL line */
+ >;
+ sda-is-open-drain;
+ scl-is-open-drain;
+ scl-is-output-only;
+ speed-hz = <250000>;
+
+ audio-video-encoder {
+ compatible = "nintendo,wii-ave-rvl";
+ reg = <70>;
+ };
+};
diff --git a/drivers/i2c/busses/i2c-gpio.c b/drivers/i2c/busses/i2c-gpio.c
index d9aa9a6..6cc5f15 100644
--- a/drivers/i2c/busses/i2c-gpio.c
+++ b/drivers/i2c/busses/i2c-gpio.c
@@ -14,8 +14,14 @@
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
+#include <linux/gpio.h>
+#include <linux/of_i2c.h>

-#include <asm/gpio.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 +84,80 @@ static int i2c_gpio_getscl(void *data)
return gpio_get_value(pdata->scl_pin);
}

+#ifdef CONFIG_OF
+#include <linux/of_gpio.h>
+
+/* Check if devicetree nodes exist and build platform data */
+static int i2c_gpio_of_probe(struct platform_device *pdev,
+ struct i2c_gpio_platform_data *pdata)
+{
+ struct device_node *np = pdev->dev.of_node;
+ const __be32 *prop;
+ int sda_pin, scl_pin;
+ int len;
+
+ if (!np || of_gpio_count(np) < 2)
+ return -ENXIO;
+
+ sda_pin = of_get_gpio_flags(np, 0, NULL);
+ scl_pin = of_get_gpio_flags(np, 1, NULL);
+ if (sda_pin < 0 || scl_pin < 0) {
+ pr_err("%s: invalid GPIO pins, sda=%d/scl=%d\n",
+ np->full_name, sda_pin, scl_pin);
+ return -ENXIO;
+ }
+
+ pdata->sda_pin = sda_pin;
+ pdata->scl_pin = scl_pin;
+ prop = of_get_property(np, "sda-is-open-drain", NULL);
+ if (prop)
+ pdata->sda_is_open_drain = 1;
+ prop = of_get_property(np, "scl-is-open-drain", NULL);
+ if (prop)
+ pdata->scl_is_open_drain = 1;
+ prop = of_get_property(np, "scl-is-output-only", NULL);
+ if (prop)
+ pdata->scl_is_output_only = 1;
+ prop = of_get_property(np, "speed-hz", &len);
+ if (prop && len >= sizeof(__be32))
+ pdata->udelay = DIV_ROUND_UP(1000000, be32_to_cpup(prop) * 2);
+ prop = of_get_property(np, "timeout", &len);
+ if (prop && len >= sizeof(__be32))
+ pdata->timeout = msecs_to_jiffies(be32_to_cpup(prop));
+
+ return 0;
+}
+#else
+static int i2c_gpio_of_probe(struct platform_device *pdev,
+ struct i2c_gpio_platform_data *pdata)
+{
+ return -ENXIO;
+}
+#endif
+
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.platform_data) {
+ *pdata = *(struct i2c_gpio_platform_data *)
+ pdev->dev.platform_data;
+ } else {
+ ret = i2c_gpio_of_probe(pdev, pdata);
+ if (ret)
+ return ret;
+ }

ret = gpio_request(pdata->sda_pin, "sda");
if (ret)
@@ -143,6 +205,7 @@ 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.
@@ -154,13 +217,16 @@ static int __devinit i2c_gpio_probe(struct platform_device *pdev)
if (ret)
goto err_add_bus;

- platform_set_drvdata(pdev, 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,
pdata->scl_is_output_only
? ", no clock stretching" : "");

+ /* Now register all the child nodes */
+ of_i2c_register_devices(adap);
+
return 0;

err_add_bus:
@@ -168,34 +234,41 @@ err_add_bus:
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;
}

+#ifdef CONFIG_OF
+static const struct of_device_id i2c_gpio_match[] = {
+ { .compatible = "i2c-gpio", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, i2c_gpio_match);
+#else /* CONFIG_OF */
+#define i2c_gpio_match NULL
+#endif /* CONFIG_OF */
+
static struct platform_driver i2c_gpio_driver = {
.driver = {
.name = "i2c-gpio",
.owner = THIS_MODULE,
+ .of_match_table = i2c_gpio_match,
},
.probe = i2c_gpio_probe,
.remove = __devexit_p(i2c_gpio_remove),
--
1.7.4


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