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Subject[PATCH] i2c-gpio: add devicetree support
Date
This patch adds devicetree support to i2c-gpio driver. It converts
dts bindings and allocates a struct i2c_gpio_platform_data, which
will be freed on driver removal.

Signed-off-by: Albert Herranz <albert_herranz@yahoo.es>
Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
---
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.
Documentation/devicetree/bindings/i2c/i2c-gpio.txt | 40 ++++++++++
drivers/i2c/busses/i2c-gpio.c | 83 +++++++++++++++++++-
2 files changed, 119 insertions(+), 4 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..4b31bbe 100644
--- a/drivers/i2c/busses/i2c-gpio.c
+++ b/drivers/i2c/busses/i2c-gpio.c
@@ -14,8 +14,8 @@
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
-
-#include <asm/gpio.h>
+#include <linux/gpio.h>
+#include <linux/of_i2c.h>

/* Toggle SDA by changing the direction of the pin */
static void i2c_gpio_setsda_dir(void *data, int state)
@@ -78,15 +78,74 @@ 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 struct i2c_gpio_platform_data *i2c_gpio_of_probe(
+ struct platform_device *pdev)
+{
+ struct i2c_gpio_platform_data *pdata = NULL;
+ struct device_node *np = pdev->dev.of_node;
+ const __be32 *prop;
+ int sda_pin, scl_pin;
+
+ if (!np || of_gpio_count(np) < 2)
+ goto err;
+
+ 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);
+ goto err;
+ }
+
+ pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
+ if (!pdata)
+ goto err;
+
+ 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", NULL);
+ if (prop)
+ pdata->udelay = DIV_ROUND_UP(1000000, be32_to_cpup(prop) * 2);
+ prop = of_get_property(np, "timeout", NULL);
+ if (prop) {
+ pdata->timeout =
+ msecs_to_jiffies(be32_to_cpup(prop));
+ }
+err:
+ return pdata;
+}
+#else
+static struct i2c_gpio_platform_data *i2c_gpio_of_probe(
+ struct platform_device *pdev)
+{
+ return NULL;
+}
+#endif
+
static int __devinit i2c_gpio_probe(struct platform_device *pdev)
{
- struct i2c_gpio_platform_data *pdata;
+ struct i2c_gpio_platform_data *pdata, *pdata_of = NULL;
struct i2c_algo_bit_data *bit_data;
struct i2c_adapter *adap;
int ret;

pdata = pdev->dev.platform_data;
if (!pdata)
+ pdata = pdata_of = i2c_gpio_of_probe(pdev);
+ if (!pdata)
return -ENXIO;

ret = -ENOMEM;
@@ -143,6 +202,8 @@ 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;
+ if (pdata_of)
+ adap->dev.of_node = pdev->dev.of_node;

/*
* If "dev->id" is negative we consider it as zero.
@@ -161,6 +222,9 @@ static int __devinit i2c_gpio_probe(struct platform_device *pdev)
pdata->scl_is_output_only
? ", no clock stretching" : "");

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

err_add_bus:
@@ -172,6 +236,7 @@ err_request_sda:
err_alloc_bit_data:
kfree(adap);
err_alloc_adap:
+ kfree(pdata_of);
return ret;
}

@@ -179,23 +244,33 @@ static int __devexit i2c_gpio_remove(struct platform_device *pdev)
{
struct i2c_gpio_platform_data *pdata;
struct i2c_adapter *adap;
+ struct i2c_algo_bit_data *bit_data;

adap = platform_get_drvdata(pdev);
- pdata = pdev->dev.platform_data;
+ bit_data = adap->algo_data;
+ pdata = bit_data->data;

i2c_del_adapter(adap);
gpio_free(pdata->scl_pin);
gpio_free(pdata->sda_pin);
kfree(adap->algo_data);
+ if (adap->dev.of_node)
+ kfree(pdata);
kfree(adap);

return 0;
}

+static const struct of_device_id i2c_gpio_match[] = {
+ { .compatible = "i2c-gpio", },
+ {},
+};
+
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),
--
1.7.3.5


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