[PATCH 3/3 v2] i2c-gpio: add devicetree support
Thomas Chou
thomas at wytron.com.tw
Tue Feb 1 02:25:51 EST 2011
From: Albert Herranz <albert_herranz at yahoo.es>
This patch is based on an earlier patch from Albert Herranz,
http://git.infradead.org/users/herraa1/gc-linux-2.6.git/commit/
9854eb78607c641ab5ae85bcbe3c9d14ac113733
The dts binding is modified as Grant suggested. The of probing
is merged inline instead of a separate file. It uses the newer
of gpio probe.
Signed-off-by: Albert Herranz <albert_herranz at yahoo.es>
Signed-off-by: Thomas Chou <thomas at 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.
Documentation/devicetree/bindings/i2c/i2c-gpio.txt | 40 +++++++++++
drivers/i2c/busses/i2c-gpio.c | 73 +++++++++++++++++++-
2 files changed, 110 insertions(+), 3 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..541fb10
--- /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.
+- udelay : signal toggle delay. SCL frequency is (500 / udelay) kHz
+- timeout : clock stretching timeout in milliseconds.
+
+Example:
+
+gpio0: starlet-gpio at 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;
+ udelay = <2>;
+
+ 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..dbf5b85 100644
--- a/drivers/i2c/busses/i2c-gpio.c
+++ b/drivers/i2c/busses/i2c-gpio.c
@@ -14,8 +14,10 @@
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
-
-#include <asm/gpio.h>
+#include <linux/gpio.h>
+#include <linux/of_platform.h>
+#include <linux/of_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)
@@ -78,6 +80,53 @@ static int i2c_gpio_getscl(void *data)
return gpio_get_value(pdata->scl_pin);
}
+/* 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;
+
+ if (np && of_gpio_count(np) >= 2) {
+ const __be32 *prop;
+ int sda_pin, scl_pin;
+
+ 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_gpio_pin;
+ }
+ pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
+ if (!pdata)
+ goto err_alloc_pdata;
+ 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, "udelay", NULL);
+ if (prop)
+ pdata->udelay = be32_to_cpup(prop);
+ prop = of_get_property(np, "timeout", NULL);
+ if (prop) {
+ pdata->timeout =
+ msecs_to_jiffies(be32_to_cpup(prop));
+ }
+ }
+
+err_gpio_pin:
+err_alloc_pdata:
+ return pdata;
+}
+
static int __devinit i2c_gpio_probe(struct platform_device *pdev)
{
struct i2c_gpio_platform_data *pdata;
@@ -87,6 +136,8 @@ static int __devinit i2c_gpio_probe(struct platform_device *pdev)
pdata = pdev->dev.platform_data;
if (!pdata)
+ pdata = i2c_gpio_of_probe(pdev);
+ if (!pdata)
return -ENXIO;
ret = -ENOMEM;
@@ -143,6 +194,7 @@ 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.
@@ -161,6 +213,9 @@ 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 +227,8 @@ err_request_sda:
err_alloc_bit_data:
kfree(adap);
err_alloc_adap:
+ if (!pdev->dev.platform_data)
+ kfree(pdata);
return ret;
}
@@ -179,23 +236,33 @@ 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);
kfree(adap);
+ if (!pdev->dev.platform_data)
+ kfree(pdata);
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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