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

[Enric Balletbo Serra <eballetbo@gmail.com>]

Missatge de Guenter Roeck <groeck@google.com> del dia dl., 10 de des.
2018 a les 22:50:
>
> On Mon, Dec 10, 2018 at 1:27 PM Enric Balletbo Serra
> <eballetbo@gmail.com> wrote:
> >
> > Missatge de Guenter Roeck <groeck@google.com> del dia dl., 10 de des.
> > 2018 a les 19:34:
> > >
> > > On Mon, Dec 10, 2018 at 10:22 AM Enric Balletbo i Serra
> > > <enric.balletbo@collabora.com> 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@collabora.com> 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>
> > > > >> ---
> > > > >>
> > > > >> 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.
> > >
> >
> > I assumed that <something> is the standard de facto, although I don't
> > see that documented anywhere. If you do a grep it is extensively used.
> > I.e:
> >
> > stable/sysfs-class-infiniband:199:What:
> > /sys/class/infiniband/<device-name>/ports/<port-num>/hw_counters/lifespan
> > testing/sysfs-class-power:3:What:
> > /sys/class/power_supply/<supply_name>/manufacturer
> > ... and many others
> >
> That makes sense if the name is determined by the driver, and there
> are many drivers and no fixed name(s). Here we have exactly two
> possible names.
>

Although are not upstream yet, there aren't more possible names? If I
remember correctly there is also cros_fp (for a fingerprint) and
cros_tp (for a touchpad)? I am not sure which devices use those.

> > Maybe add a new entry at the beginning?
> >
> > What:          /sys/class/chromeos/<cros-ec-name>
> > ...
> > Description:
> >               The cros-ec device name, i.e. cros_ec or cros_pd.
> >
> How about {cros_ec,cros_pd} instead of <cros-ec> ?
> I see that used a few times where the names are well defined.
>

Sounds good to me if the list is fixed, if needs to increase I don't
think it will be really friendly. Or we can do this way and change if
the list grows.

Cheers,
 Enric

> Thanks,
> Guenter
>
> > > 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
> > > > >>
> > > > >