Re: [PATCH v3 5/8] mfd / platform: cros_ec: move device sysfs attributes to its own driver.

[Guenter Roeck]

On Mon, Dec 10, 2018 at 10:22 AM Enric Balletbo i Serra
<enric.balletbo@xxxxxxxxxxxxx> wrote:
>
> Hi Guenter,
>
> On 10/12/18 19:13, Guenter Roeck wrote:
> > On Tue, Nov 27, 2018 at 4:19 AM Enric Balletbo i Serra
> > <enric.balletbo@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxx>
> >> ---
> >>
> >> Changes in v3:
> >> - Do not print ec_platform name as is with dev_err is enough.
> >>
> >> Changes in v2:
> >> - Create the attributes directly instead of use the attach/detach callbacks.
> >>
> >>  .../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       | 36 ++++++++++++++++++-
> >>  include/linux/mfd/cros_ec.h                   |  3 --
> >>  7 files changed, 80 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
> >
> > Why "<cros-ec>" and not "cros_ec" ?
> >
>
> Maybe will be more clear if I use <cros-ec-name>?
>
> Actually <cros-ec-name> can be cros_ec or cros_pd. I put between <> to indicate
> that is not the literal name.
>
Should that be mentioned somewhere ? Readers of this document won't
know what it stands for.

Thanks,
Guenter

> >> +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 50ba8e0fb4ec..d9b16ce79319 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,
> >>  };
> >>
> >>  /* Basic communication */
> >> @@ -391,6 +385,7 @@ 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 4e4232b47764..b709cc5173a2 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
> >> @@ -142,4 +139,15 @@ 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
> >
> > In practice this is limited to MFD_CROS_EC_CHARDEV, meaning it will be
> > set to m if MFD_CROS_EC_CHARDEV=m.
> > Not sure what is better here, but for consistency I would prefer
> > "default MFD_CROS_EC_CHARDEV" (or default y
> > in the entire series).
> >
>
> Right, makes sense that if the MFD_CROS_EC_CHARDEV is selected set also those by
> default. Will prepare a new version with that small change.
>
> >> +       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..0ff5aa30c070 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 +355,39 @@ struct attribute_group cros_ec_attr_group = {
> >>         .attrs = __ec_attrs,
> >>         .is_visible = cros_ec_ctrl_visible,
> >>  };
> >> -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 device *dev = &pd->dev;
> >> +       int ret;
> >> +
> >> +       ret = sysfs_create_group(&ec_dev->class_dev.kobj, &cros_ec_attr_group);
> >> +       if (ret < 0)
> >> +               dev_err(dev, "failed to create attributes. err=%d\n", ret);
> >> +
> >> +       return ret;
> >> +}
> >> +
> >> +static int cros_ec_sysfs_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_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 3e4401e2ceea..f718ad9c2132 100644
> >> --- a/include/linux/mfd/cros_ec.h
> >> +++ b/include/linux/mfd/cros_ec.h
> >> @@ -323,7 +323,4 @@ 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;
> >> -
> >>  #endif /* __LINUX_MFD_CROS_EC_H */
> >> --
> >> 2.19.1
> >>
> >