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

[Enric Balletbo i Serra]

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.

>> +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
>>
>