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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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