On Thu, 19 Jul 2012 13:19:24 +0200, Jean Delvare wrote:
> GPIOs may not be available immediately when i2c-gpio looks for them.
> Implement support for deferred probing so that probing can be
> attempted again later when GPIO pins are finally available.
>
> Signed-off-by: Jean Delvare <[email protected]>
> Cc: Haavard Skinnemoen <[email protected]>
> ---
> A little more changes were needed than I initially thought, because we
> want to check the pins before we allocate memory. Otherwise we would
> have a possibly large number of memory allocation and freeing cycles
> until GPIO pins are finally available.
>
> Note: I wrote this patch for someone else, I can't test it, so I would
> appreciate if someone could at least test and confirm that I did not
> break anything in the standard (non-deferred) case. Thanks!
Anyone, please? Anyone using i2c-gpio, please test this patch and
report how it goes. Thanks.
> drivers/i2c/busses/i2c-gpio.c | 76
> +++++++++++++++++++++++++++--------------
> 1 file changed, 51 insertions(+), 25 deletions(-)
>
> --- linux-3.5-rc5.orig/drivers/i2c/busses/i2c-gpio.c 2012-06-05
> 16:22:59.000000000 +0200
> +++ linux-3.5-rc5/drivers/i2c/busses/i2c-gpio.c 2012-07-07
> 10:53:40.911407245 +0200
> @@ -85,23 +85,30 @@ 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)
> +static int __devinit of_i2c_gpio_get_pins(struct device_node *np,
> + unsigned int *sda_pin,
> + unsigned int *scl_pin)
> {
> - 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);
> + *sda_pin = of_get_gpio(np, 0);
> + *scl_pin = of_get_gpio(np, 1);
>
> - if (!gpio_is_valid(pdata->sda_pin) || !gpio_is_valid(pdata->scl_pin)) {
> + if (!gpio_is_valid(*sda_pin) || !gpio_is_valid(*scl_pin)) {
> pr_err("%s: invalid GPIO pins, sda=%d/scl=%d\n",
> - np->full_name, pdata->sda_pin, pdata->scl_pin);
> + np->full_name, *sda_pin, *scl_pin);
> return -ENODEV;
> }
>
> + return 0;
> +}
> +
> +static void __devinit of_i2c_gpio_get_props(struct device_node *np,
> + struct i2c_gpio_platform_data *pdata)
> +{
> + u32 reg;
> +
> of_property_read_u32(np, "i2c-gpio,delay-us", &pdata->udelay);
>
> if (!of_property_read_u32(np, "i2c-gpio,timeout-ms", ®))
> @@ -113,8 +120,6 @@ static int __devinit of_i2c_gpio_probe(s
> 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)
> @@ -123,31 +128,52 @@ static int __devinit i2c_gpio_probe(stru
> struct i2c_gpio_platform_data *pdata;
> struct i2c_algo_bit_data *bit_data;
> struct i2c_adapter *adap;
> + unsigned int sda_pin, scl_pin;
> int ret;
>
> - priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> - if (!priv)
> - return -ENOMEM;
> - adap = &priv->adap;
> - bit_data = &priv->bit_data;
> - pdata = &priv->pdata;
> -
> + /* First get the GPIO pins; if it fails, we'll defer the probe. */
> if (pdev->dev.of_node) {
> - ret = of_i2c_gpio_probe(pdev->dev.of_node, pdata);
> + ret = of_i2c_gpio_get_pins(pdev->dev.of_node,
> + &sda_pin, &scl_pin);
> if (ret)
> return ret;
> } else {
> if (!pdev->dev.platform_data)
> return -ENXIO;
> - memcpy(pdata, pdev->dev.platform_data, sizeof(*pdata));
> + pdata = pdev->dev.platform_data;
> + sda_pin = pdata->sda_pin;
> + scl_pin = pdata->scl_pin;
> }
>
> - ret = gpio_request(pdata->sda_pin, "sda");
> - if (ret)
> + ret = gpio_request(sda_pin, "sda");
> + if (ret) {
> + if (ret == -EINVAL)
> + ret = -EPROBE_DEFER; /* Try again later */
> goto err_request_sda;
> - ret = gpio_request(pdata->scl_pin, "scl");
> - if (ret)
> + }
> + ret = gpio_request(scl_pin, "scl");
> + if (ret) {
> + if (ret == -EINVAL)
> + ret = -EPROBE_DEFER; /* Try again later */
> goto err_request_scl;
> + }
> +
> + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> + if (!priv) {
> + ret = -ENOMEM;
> + goto err_add_bus;
> + }
> + adap = &priv->adap;
> + bit_data = &priv->bit_data;
> + pdata = &priv->pdata;
> +
> + if (pdev->dev.of_node) {
> + pdata->sda_pin = sda_pin;
> + pdata->scl_pin = scl_pin;
> + of_i2c_gpio_get_props(pdev->dev.of_node, pdata);
> + } else {
> + memcpy(pdata, pdev->dev.platform_data, sizeof(*pdata));
> + }
>
> if (pdata->sda_is_open_drain) {
> gpio_direction_output(pdata->sda_pin, 1);
> @@ -207,9 +233,9 @@ static int __devinit i2c_gpio_probe(stru
> return 0;
>
> err_add_bus:
> - gpio_free(pdata->scl_pin);
> + gpio_free(scl_pin);
> err_request_scl:
> - gpio_free(pdata->sda_pin);
> + gpio_free(sda_pin);
> err_request_sda:
> return ret;
> }
>
>
--
Jean Delvare
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