Re: [PATCH v2 2/3] power: gpio-charger: add device tree support

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Heiko

On Sun, Sep 21, 2014 at 1:05 PM, Heiko Stuebner <heiko@xxxxxxxxx> wrote:
> From: Heiko Stuebner <heiko.stuebner@xxxxxx>
>
> Add the ability to parse gpio-charger data from a devicetree node.
>
> Signed-off-by: Heiko Stuebner <heiko.stuebner@xxxxxx>
> ---
>  drivers/power/gpio-charger.c | 66 ++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 63 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/power/gpio-charger.c b/drivers/power/gpio-charger.c
> index a0024b2..5fe6879 100644
> --- a/drivers/power/gpio-charger.c
> +++ b/drivers/power/gpio-charger.c
> @@ -22,6 +22,8 @@
>  #include <linux/platform_device.h>
>  #include <linux/power_supply.h>
>  #include <linux/slab.h>
> +#include <linux/of.h>
> +#include <linux/of_gpio.h>
>
>  #include <linux/power/gpio-charger.h>
>
> @@ -69,17 +71,68 @@ static enum power_supply_property gpio_charger_properties[] = {
>         POWER_SUPPLY_PROP_ONLINE,
>  };
>
> +static
> +struct gpio_charger_platform_data *gpio_charger_parse_dt(struct device *dev)
> +{
> +       struct device_node *np = dev->of_node;
> +       struct gpio_charger_platform_data *pdata;
> +       const char *chargetype;
> +       enum of_gpio_flags flags;
> +       int ret;
> +
> +       if (!np)
> +               return ERR_PTR(-ENOENT);
> +
> +       pdata = devm_kzalloc(dev, sizeof(struct gpio_charger_platform_data),

nit: sizeof(*pdata) is smaller / cleaner.

> +                            GFP_KERNEL);
> +       if (!pdata)
> +               return ERR_PTR(-ENOMEM);
> +
> +       pdata->name = np->name;
> +
> +       pdata->gpio = of_get_gpio_flags(np, 0, &flags);

It would be nice to check the gpio for errors here, including handling
the possibility of EPROBE_DEFER.


> +       pdata->gpio_active_low = flags & OF_GPIO_ACTIVE_LOW;
> +
> +       pdata->type = POWER_SUPPLY_TYPE_UNKNOWN;
> +       ret = of_property_read_string(np, "charger-type", &chargetype);
> +       if (ret >= 0) {
> +               if (!strncmp("unknown", chargetype, 7))
> +                       pdata->type = POWER_SUPPLY_TYPE_UNKNOWN;
> +               else if (!strncmp("battery", chargetype, 7))
> +                       pdata->type = POWER_SUPPLY_TYPE_BATTERY;
> +               else if (!strncmp("ups", chargetype, 3))
> +                       pdata->type = POWER_SUPPLY_TYPE_UPS;
> +               else if (!strncmp("mains", chargetype, 5))
> +                       pdata->type = POWER_SUPPLY_TYPE_MAINS;
> +               else if (!strncmp("usb-sdp", chargetype, 7))
> +                       pdata->type = POWER_SUPPLY_TYPE_USB;
> +               else if (!strncmp("usb-dcp", chargetype, 7))
> +                       pdata->type = POWER_SUPPLY_TYPE_USB_DCP;
> +               else if (!strncmp("usb-cdp", chargetype, 7))
> +                       pdata->type = POWER_SUPPLY_TYPE_USB_CDP;
> +               else if (!strncmp("usb-aca", chargetype, 7))
> +                       pdata->type = POWER_SUPPLY_TYPE_USB_ACA;
> +               else
> +                       dev_warn(dev, "unknown charger type %s\n", chargetype);
> +       }
> +
> +       return pdata;
> +}
> +
>  static int gpio_charger_probe(struct platform_device *pdev)
>  {
> -       const struct gpio_charger_platform_data *pdata = pdev->dev.platform_data;
> +       struct gpio_charger_platform_data *pdata = pdev->dev.platform_data;

Do you really need to remove const?  If I remember correctly the const
here is not saying that the variable "pdata" won't change but that the
data pointed to by pdata won't change.  I think that's still the case
(from the perspective of this function).


>         struct gpio_charger *gpio_charger;
>         struct power_supply *charger;
>         int ret;
>         int irq;
>
>         if (!pdata) {
> -               dev_err(&pdev->dev, "No platform data\n");
> -               return -EINVAL;
> +               pdata = gpio_charger_parse_dt(&pdev->dev);
> +               if (IS_ERR(pdata)) {
> +                       dev_err(&pdev->dev, "No platform data\n");
> +                       return -EINVAL;

Probably should pass back the error code since it might be
EPROBE_DEFER.  ...and <sigh> I guess you need the special case of
"don't print if it's EPROBE_DEFER".  I almost wish we had a helper
function for that.  ;)


> +               }
>         }
>
>         if (!gpio_is_valid(pdata->gpio)) {
> @@ -189,6 +242,12 @@ static int gpio_charger_resume(struct device *dev)
>  static SIMPLE_DEV_PM_OPS(gpio_charger_pm_ops,
>                 gpio_charger_suspend, gpio_charger_resume);
>
> +static const struct of_device_id gpio_charger_match[] = {
> +       { .compatible = "gpio-charger" },
> +       { }
> +};
> +MODULE_DEVICE_TABLE(of, gpio_charger_match);
> +
>  static struct platform_driver gpio_charger_driver = {
>         .probe = gpio_charger_probe,
>         .remove = gpio_charger_remove,
> @@ -196,6 +255,7 @@ static struct platform_driver gpio_charger_driver = {
>                 .name = "gpio-charger",
>                 .owner = THIS_MODULE,
>                 .pm = &gpio_charger_pm_ops,
> +               .of_match_table = of_match_ptr(gpio_charger_match),

Given that you don't have any #ifdefs with "CONFIG_OF", I think
gpio_charger_match will always exist.  It seems like you should remove
the of_match_ptr or add some #ifdefs.  I can't quite keep up with what
the currently suggested best practice is here, though.

-Doug
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