linux-kernel - Re: [PATCH v3 6/8] mfd / platform: cros_ec: instantiate only if th EC has a VBC NVRAM.

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Message-ID: <CABXOdTd3_KGfJG-E7UBgnxKJcyFNVZ2FqdqH6y-G0gkEUZjk0Q@mail.gmail.com>
Date:   Mon, 10 Dec 2018 10:15:05 -0800
From:   Guenter Roeck <groeck@...gle.com>
To:     Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc:     Lee Jones <lee.jones@...aro.org>,
        Gwendal Grignou <gwendal@...omium.org>,
        Nicolas Boichat <drinkcat@...omium.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Guenter Roeck <groeck@...omium.org>, kernel@...labora.com,
        Benson Leung <bleung@...omium.org>,
        Olof Johansson <olof@...om.net>
Subject: Re: [PATCH v3 6/8] mfd / platform: cros_ec: instantiate only if th EC
 has a VBC NVRAM.

On Tue, Nov 27, 2018 at 4:19 AM Enric Balletbo i Serra
<enric.balletbo@...labora.com> wrote:
>
> The cros-ec-vbc driver is DT-only and there is a DT property that
> indicates if the EC has the VCB NVRAM, in such case instantiate the
> driver but don't instantiate on the other cases.
>
> To do this move the check code to its parent instead of play with the
> attribute group visibility. This changes a bit the actual behaviour.
> Before the patch if an EC doesn't have a VBC NVRAM an empty vbc folder
> is created in /sys/class/chromeos/<ec device>, after the patch the empty
> folder is not created, so, the folder is only created if the vbc is set.
>
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>

Reviewed-by: Guenter Roeck <groeck@...omium.org>

> ---
>
> Changes in v3:
> - Fixed build error as reported by kbuild test robot.
>
> Changes in v2:
> - Remove unnecessary IS_ENABLED.
> - Remove dev_err message telling that VBC is found.
> - Use dev_warn instead of dev_err as the error is ignored.
>
>  drivers/mfd/cros_ec_dev.c             | 19 ++++++++++++++++++-
>  drivers/platform/chrome/cros_ec_vbc.c | 16 ----------------
>  2 files changed, 18 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
> index d9b16ce79319..1ba98a32715e 100644
> --- a/drivers/mfd/cros_ec_dev.c
> +++ b/drivers/mfd/cros_ec_dev.c
> @@ -21,6 +21,7 @@
>  #include <linux/mfd/core.h>
>  #include <linux/module.h>
>  #include <linux/mod_devicetable.h>
> +#include <linux/of_platform.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm.h>
>  #include <linux/slab.h>
> @@ -386,12 +387,16 @@ static const struct mfd_cell cros_ec_platform_cells[] = {
>         { .name = "cros-ec-debugfs" },
>         { .name = "cros-ec-lightbar" },
>         { .name = "cros-ec-sysfs" },
> -       { .name = "cros-ec-vbc" },
> +};
> +
> +static const struct mfd_cell cros_ec_vbc_cells[] = {
> +       { .name = "cros-ec-vbc" }
>  };
>
>  static int ec_device_probe(struct platform_device *pdev)
>  {
>         int retval = -ENOMEM;
> +       struct device_node *node;
>         struct device *dev = &pdev->dev;
>         struct cros_ec_platform *ec_platform = dev_get_platdata(dev);
>         struct cros_ec_dev *ec = devm_kzalloc(dev, sizeof(*ec), GFP_KERNEL);
> @@ -479,6 +484,18 @@ static int ec_device_probe(struct platform_device *pdev)
>                          "failed to add cros-ec platform devices: %d\n",
>                          retval);
>
> +       /* Check whether this EC instance has a VBC NVRAM */
> +       node = ec->ec_dev->dev->of_node;
> +       if (of_property_read_bool(node, "google,has-vbc-nvram")) {
> +               retval = mfd_add_devices(ec->dev, PLATFORM_DEVID_AUTO,
> +                                        cros_ec_vbc_cells,
> +                                        ARRAY_SIZE(cros_ec_vbc_cells),
> +                                        NULL, 0, NULL);
> +               if (retval)
> +                       dev_warn(ec->dev, "failed to add VBC devices: %d\n",
> +                                retval);
> +       }
> +
>         return 0;
>
>  failed:
> diff --git a/drivers/platform/chrome/cros_ec_vbc.c b/drivers/platform/chrome/cros_ec_vbc.c
> index da3bbf05e86f..af9bfe6f385c 100644
> --- a/drivers/platform/chrome/cros_ec_vbc.c
> +++ b/drivers/platform/chrome/cros_ec_vbc.c
> @@ -108,21 +108,6 @@ static ssize_t vboot_context_write(struct file *filp, struct kobject *kobj,
>         return data_sz;
>  }
>
> -static umode_t cros_ec_vbc_is_visible(struct kobject *kobj,
> -                                     struct bin_attribute *a, int n)
> -{
> -       struct device *dev = container_of(kobj, struct device, kobj);
> -       struct cros_ec_dev *ec = to_cros_ec_dev(dev);
> -       struct device_node *np = ec->ec_dev->dev->of_node;
> -
> -       if (IS_ENABLED(CONFIG_OF) && np) {
> -               if (of_property_read_bool(np, "google,has-vbc-nvram"))
> -                       return a->attr.mode;
> -       }
> -
> -       return 0;
> -}
> -
>  static BIN_ATTR_RW(vboot_context, 16);
>
>  static struct bin_attribute *cros_ec_vbc_bin_attrs[] = {
> @@ -133,7 +118,6 @@ static struct bin_attribute *cros_ec_vbc_bin_attrs[] = {
>  struct attribute_group cros_ec_vbc_attr_group = {
>         .name = "vbc",
>         .bin_attrs = cros_ec_vbc_bin_attrs,
> -       .is_bin_visible = cros_ec_vbc_is_visible,
>  };
>
>  static int cros_ec_vbc_probe(struct platform_device *pd)
> --
> 2.19.1
>