Re: [PATCH 5/7] mfd / platform: cros_ec: move device sysfs attributes to its own driver.

Guenter Roeck
2018-11-22T19:10:01Z

On Thu, Nov 22, 2018 at 12:33:54PM +0100, Enric Balletbo i Serra wrote:
> The entire way how cros debugfs attibutes are created is broken.
> cros_ec_sysfs should be its own driver and its attributes should be
> associated with the sysfs driver not the mfd driver.
>
> The patch also adds the sysfs documentation.
>
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
> ---
>
> .../ABI/testing/sysfs-class-chromeos | 32 ++++++++++++++
> drivers/mfd/Kconfig | 1 -
> drivers/mfd/cros_ec_dev.c | 7 +--
> drivers/platform/chrome/Kconfig | 14 ++++--
> drivers/platform/chrome/Makefile | 3 +-
> drivers/platform/chrome/cros_ec_sysfs.c | 43 ++++++++++++++++++-
> include/linux/mfd/cros_ec.h | 3 --
> 7 files changed, 87 insertions(+), 16 deletions(-)
> create mode 100644 Documentation/ABI/testing/sysfs-class-chromeos
>
> diff --git a/Documentation/ABI/testing/sysfs-class-chromeos b/Documentation/ABI/testing/sysfs-class-chromeos
> new file mode 100644
> index 000000000000..a5399c4ca82d
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-chromeos
> @@ -0,0 +1,32 @@
> +What: /sys/class/chromeos/<cros-ec>/flashinfo
> +Date: August 2015
> +KernelVersion: 4.2
> +Description:
> + Show the EC flash information.
> +
> +What: /sys/class/chromeos/<cros-ec>/kb_wake_angle
> +Date: March 2018
> +KernelVersion: 4.17
> +Description:
> + Control the keyboard wake lid angle. Values are between
> + 0 and 360. This file will also show the keyboard wake lid
> + angle by querying the hardware.
> +
> +What: /sys/class/chromeos/<cros-ec>/reboot
> +Date: August 2015
> +KernelVersion: 4.2
> +Description:
> + Tell the EC to reboot in various ways. Options are:
> + "cancel": Cancel a pending reboot.
> + "ro": Jump to RO without rebooting.
> + "rw": Jump to RW without rebooting.
> + "cold": Cold reboot.
> + "disable-jump": Disable jump until next reboot.
> + "hibernate": Hibernate the EC.
> + "at-shutdown": Reboot after an AP shutdown.
> +
> +What: /sys/class/chromeos/<cros-ec>/version
> +Date: August 2015
> +KernelVersion: 4.2
> +Description:
> + Show the information about the EC software and hardware.
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 8c5dfdce4326..089ffb408918 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -214,7 +214,6 @@ config MFD_CROS_EC
> config MFD_CROS_EC_CHARDEV
> tristate "Chrome OS Embedded Controller userspace device interface"
> depends on MFD_CROS_EC
> - select CROS_EC_CTL
> ---help---
> This driver adds support to talk with the ChromeOS EC from userspace.
>
> diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
> index 8c7ee2a0b50a..fc235af6da65 100644
> --- a/drivers/mfd/cros_ec_dev.c
> +++ b/drivers/mfd/cros_ec_dev.c
> @@ -34,15 +34,9 @@
> #define CROS_MAX_DEV 128
> static int ec_major;
>
> -static const struct attribute_group *cros_ec_groups[] = {
> - &cros_ec_attr_group,
> - NULL,
> -};
> -
> static struct class cros_class = {
> .owner = THIS_MODULE,
> .name = "chromeos",
> - .dev_groups = cros_ec_groups,
> };
>
> int cros_ec_attach_attribute_group(struct cros_ec_dev *ec,
> @@ -405,6 +399,7 @@ static const struct mfd_cell cros_usbpd_charger_cells[] = {
> 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" },
> };
>
> diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
> index a1239d48c46f..2ef51520766a 100644
> --- a/drivers/platform/chrome/Kconfig
> +++ b/drivers/platform/chrome/Kconfig
> @@ -49,9 +49,6 @@ config CHROMEOS_TBMC
> To compile this driver as a module, choose M here: the
> module will be called chromeos_tbmc.
>
> -config CROS_EC_CTL
> - tristate
> -
> config CROS_EC_I2C
> tristate "ChromeOS Embedded Controller (I2C)"
> depends on MFD_CROS_EC && I2C
> @@ -141,4 +138,15 @@ config CROS_EC_DEBUGFS
> To compile this driver as a module, choose M here: the
> module will be called cros_ec_debugfs.
>
> +config CROS_EC_SYSFS
> + tristate "ChromeOS EC control and information through sysfs"
> + depends on MFD_CROS_EC_CHARDEV && SYSFS
> + default y
> + help
> + This option exposes some sysfs attributes to control and get
> + information from ChromeOS EC.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called cros_ec_sysfs.
> +
> endif # CHROMEOS_PLATFORMS
> diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
> index 12a5c4d18c17..fdbee501931b 100644
> --- a/drivers/platform/chrome/Makefile
> +++ b/drivers/platform/chrome/Makefile
> @@ -3,8 +3,6 @@
> obj-$(CONFIG_CHROMEOS_LAPTOP) += chromeos_laptop.o
> obj-$(CONFIG_CHROMEOS_PSTORE) += chromeos_pstore.o
> obj-$(CONFIG_CHROMEOS_TBMC) += chromeos_tbmc.o
> -cros_ec_ctl-objs := cros_ec_sysfs.o
> -obj-$(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
> cros_ec_lpcs-objs := cros_ec_lpc.o cros_ec_lpc_reg.o
> @@ -15,3 +13,4 @@ obj-$(CONFIG_CROS_KBD_LED_BACKLIGHT) += cros_kbd_led_backlight.o
> obj-$(CONFIG_CROS_EC_LIGHTBAR) += cros_ec_lightbar.o
> obj-$(CONFIG_CROS_EC_VBC) += cros_ec_vbc.o
> obj-$(CONFIG_CROS_EC_DEBUGFS) += cros_ec_debugfs.o
> +obj-$(CONFIG_CROS_EC_SYSFS) += cros_ec_sysfs.o
> diff --git a/drivers/platform/chrome/cros_ec_sysfs.c b/drivers/platform/chrome/cros_ec_sysfs.c
> index f34a50121064..47d08a8f0542 100644
> --- a/drivers/platform/chrome/cros_ec_sysfs.c
> +++ b/drivers/platform/chrome/cros_ec_sysfs.c
> @@ -34,6 +34,8 @@
> #include <linux/types.h>
> #include <linux/uaccess.h>
>
> +#define DRV_NAME "cros-ec-sysfs"
> +
> /* Accessor functions */
>
> static ssize_t reboot_show(struct device *dev,
> @@ -353,7 +355,46 @@ struct attribute_group cros_ec_attr_group = {
> .attrs = __ec_attrs,
> .is_visible = cros_ec_ctrl_visible,

I think the .is_visible evaluation should now happen in the probe fuction.

> };
> -EXPORT_SYMBOL(cros_ec_attr_group);
> +
> +static int cros_ec_sysfs_probe(struct platform_device *pd)
> +{
> + struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
> + struct cros_ec_platform *ec_platform = dev_get_platdata(ec_dev->dev);
> + struct device *dev = &pd->dev;
> + int ret;
> +
> + if (!ec_dev) {
> + dev_err(dev, "No EC dev found\n");
> + return -EINVAL;
> + }

Above:

struct cros_ec_platform *ec_platform = dev_get_platdata(ec_dev->dev);

so if ec_dev is ever NULL, we'll never get to this point (and static
analyzers will have a field day). I think the check is unnecessary.

> +
> + ret = cros_ec_attach_attribute_group(ec_dev, &cros_ec_attr_group);
> + if (ret < 0)
> + dev_err(dev, "failed to create %s attributes. err=%d\n",
> + ec_platform->ec_name, ret);

Does it really make sense to display ec_platform->ec_name here ?
"Failed to create sysfs attributes" with dev_err should be good enough.

Also, again, I think we should create the attribute directly and drop
cros_ec_attach_attribute_group().

> +
> + return ret;
> +}
> +
> +static int cros_ec_sysfs_remove(struct platform_device *pd)
> +{
> + struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
> +
> + cros_ec_detach_attribute_group(ec_dev, &cros_ec_attr_group);
> +
> + return 0;
> +}
> +
> +static struct platform_driver cros_ec_sysfs_driver = {
> + .driver = {
> + .name = DRV_NAME,
> + },
> + .probe = cros_ec_sysfs_probe,
> + .remove = cros_ec_sysfs_remove,
> +};
> +
> +module_platform_driver(cros_ec_sysfs_driver);
>
> MODULE_LICENSE("GPL");
> MODULE_DESCRIPTION("ChromeOS EC control driver");
> +MODULE_ALIAS("platform:" DRV_NAME);
> diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> index 1722c2c26143..6d8618894a45 100644
> --- a/include/linux/mfd/cros_ec.h
> +++ b/include/linux/mfd/cros_ec.h
> @@ -333,9 +333,6 @@ int cros_ec_get_next_event(struct cros_ec_device *ec_dev, bool *wake_event);
> */
> u32 cros_ec_get_host_event(struct cros_ec_device *ec_dev);
>
> -/* sysfs stuff */
> -extern struct attribute_group cros_ec_attr_group;
> -
> /* Attach/detach attributes to the cros_class */
> extern int cros_ec_attach_attribute_group(struct cros_ec_dev *ec,
> struct attribute_group *attrs);