Re: [PATCH v3 3/8] mfd / platform: cros_ec: move vbc attributes to its own driver.

From: Guenter Roeck
Date: Thu Nov 29 2018 - 18:36:44 EST

On Tue, Nov 27, 2018 at 4:19 AM Enric Balletbo i Serra
<enric.balletbo@xxxxxxxxxxxxx> wrote:
>
> The entire way how cros sysfs attibutes are created is broken.
> cros_ec_vbc should be its own driver and its attributes should be
> associated with a vbc driver not the mfd driver. In order to retain
> the path, the vbc attributes are attached to the cros_class.
>
> The patch also adds the sysfs documentation.
>
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>

Reviewed-by: Guenter Roeck <groeck@xxxxxxxxxxxx>

> ---
>
> Changes in v3:
> - Fixed build error as reported by the kbuild test robot.
>
> Changes in v2:
> - Removed unneeded check of ec_dev.
>
> .../sysfs-class-chromeos-driver-cros-ec-vbc | 6 +++
> drivers/mfd/cros_ec_dev.c | 2 +-
> drivers/platform/chrome/Kconfig | 10 +++++
> drivers/platform/chrome/Makefile | 3 +-
> drivers/platform/chrome/cros_ec_vbc.c | 43 ++++++++++++++++++-
> include/linux/mfd/cros_ec.h | 1 -
> 6 files changed, 61 insertions(+), 4 deletions(-)
> create mode 100644 Documentation/ABI/testing/sysfs-class-chromeos-driver-cros-ec-vbc
>
> diff --git a/Documentation/ABI/testing/sysfs-class-chromeos-driver-cros-ec-vbc b/Documentation/ABI/testing/sysfs-class-chromeos-driver-cros-ec-vbc
> new file mode 100644
> index 000000000000..c256a2febf37
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-chromeos-driver-cros-ec-vbc
> @@ -0,0 +1,6 @@
> +What: /sys/class/chromeos/<cros-ec>/vbc/vboot_context
> +Date: October 2015
> +KernelVersion: 4.4
> +Description:
> + Read/write the verified boot context data included on a
> + small nvram space on some EC implementations.
> diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
> index 614f888c9d6d..51325049690c 100644
> --- a/drivers/mfd/cros_ec_dev.c
> +++ b/drivers/mfd/cros_ec_dev.c
> @@ -36,7 +36,6 @@ static int ec_major;
>
> static const struct attribute_group *cros_ec_groups[] = {
> &cros_ec_attr_group,
> - &cros_ec_vbc_attr_group,
> NULL,
> };
>
> @@ -391,6 +390,7 @@ static const struct mfd_cell cros_usbpd_charger_cells[] = {
>
> static const struct mfd_cell cros_ec_platform_cells[] = {
> { .name = "cros-ec-lightbar" },
> + { .name = "cros-ec-vbc" },
> };
>
> static int ec_device_probe(struct platform_device *pdev)
> diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
> index 05bcefbe1926..29bd9837d520 100644
> --- a/drivers/platform/chrome/Kconfig
> +++ b/drivers/platform/chrome/Kconfig
> @@ -121,4 +121,14 @@ config CROS_EC_LIGHTBAR
> To compile this driver as a module, choose M here: the
> module will be called cros_ec_lightbar.
>
> +config CROS_EC_VBC
> + tristate "ChromeOS EC vboot context support"
> + depends on MFD_CROS_EC_CHARDEV && OF
> + help
> + This option exposes the ChromeOS EC vboot context nvram to
> + userspace.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called cros_ec_vbc.
> +
> endif # CHROMEOS_PLATFORMS
> diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
> index 3c29a4b405d5..4081b7179df7 100644
> --- a/drivers/platform/chrome/Makefile
> +++ b/drivers/platform/chrome/Makefile
> @@ -4,7 +4,7 @@ obj-$(CONFIG_CHROMEOS_LAPTOP) += chromeos_laptop.o
> obj-$(CONFIG_CHROMEOS_PSTORE) += chromeos_pstore.o
> obj-$(CONFIG_CHROMEOS_TBMC) += chromeos_tbmc.o
> cros_ec_ctl-objs := cros_ec_sysfs.o \
> - cros_ec_vbc.o cros_ec_debugfs.o
> + cros_ec_debugfs.o
> obj-$(CONFIG_CROS_EC_CTL) += cros_ec_ctl.o
> obj-$(CONFIG_CROS_EC_I2C) += cros_ec_i2c.o
> obj-$(CONFIG_CROS_EC_SPI) += cros_ec_spi.o
> @@ -14,3 +14,4 @@ obj-$(CONFIG_CROS_EC_LPC) += cros_ec_lpcs.o
> obj-$(CONFIG_CROS_EC_PROTO) += cros_ec_proto.o
> obj-$(CONFIG_CROS_KBD_LED_BACKLIGHT) += cros_kbd_led_backlight.o
> obj-$(CONFIG_CROS_EC_LIGHTBAR) += cros_ec_lightbar.o
> +obj-$(CONFIG_CROS_EC_VBC) += cros_ec_vbc.o
> diff --git a/drivers/platform/chrome/cros_ec_vbc.c b/drivers/platform/chrome/cros_ec_vbc.c
> index 5356f26bc022..da3bbf05e86f 100644
> --- a/drivers/platform/chrome/cros_ec_vbc.c
> +++ b/drivers/platform/chrome/cros_ec_vbc.c
> @@ -22,8 +22,11 @@
> #include <linux/platform_device.h>
> #include <linux/mfd/cros_ec.h>
> #include <linux/mfd/cros_ec_commands.h>
> +#include <linux/module.h>
> #include <linux/slab.h>
>
> +#define DRV_NAME "cros-ec-vbc"
> +
> static ssize_t vboot_context_read(struct file *filp, struct kobject *kobj,
> struct bin_attribute *att, char *buf,
> loff_t pos, size_t count)
> @@ -132,4 +135,42 @@ struct attribute_group cros_ec_vbc_attr_group = {
> .bin_attrs = cros_ec_vbc_bin_attrs,
> .is_bin_visible = cros_ec_vbc_is_visible,
> };
> -EXPORT_SYMBOL(cros_ec_vbc_attr_group);
> +
> +static int cros_ec_vbc_probe(struct platform_device *pd)
> +{
> + struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
> + struct device *dev = &pd->dev;
> + int ret;
> +
> + ret = sysfs_create_group(&ec_dev->class_dev.kobj,
> + &cros_ec_vbc_attr_group);
> + if (ret < 0)
> + dev_err(dev, "failed to create %s attributes. err=%d\n",
> + cros_ec_vbc_attr_group.name, ret);
> +
> + return ret;
> +}
> +
> +static int cros_ec_vbc_remove(struct platform_device *pd)
> +{
> + struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
> +
> + sysfs_remove_group(&ec_dev->class_dev.kobj,
> + &cros_ec_vbc_attr_group);
> +
> + return 0;
> +}
> +
> +static struct platform_driver cros_ec_vbc_driver = {
> + .driver = {
> + .name = DRV_NAME,
> + },
> + .probe = cros_ec_vbc_probe,
> + .remove = cros_ec_vbc_remove,
> +};
> +
> +module_platform_driver(cros_ec_vbc_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Expose the vboot context nvram to userspace");
> +MODULE_ALIAS("platform:" DRV_NAME);
> diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> index b6beba3031ba..bbbe416fd573 100644
> --- a/include/linux/mfd/cros_ec.h
> +++ b/include/linux/mfd/cros_ec.h
> @@ -325,7 +325,6 @@ u32 cros_ec_get_host_event(struct cros_ec_device *ec_dev);
>
> /* sysfs stuff */
> extern struct attribute_group cros_ec_attr_group;
> -extern struct attribute_group cros_ec_vbc_attr_group;
>
> /* debugfs stuff */
> int cros_ec_debugfs_init(struct cros_ec_dev *ec);
> --
> 2.19.1
>