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

From: Enric Balletbo Serra
Date: Mon Dec 10 2018 - 16:27:51 EST

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Missatge de Guenter Roeck <groeck@xxxxxxxxxx> 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@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.
>

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

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.

> 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
> > >>
> > >

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In reply to: Guenter Roeck: "Re: [PATCH v3 5/8] mfd / platform: cros_ec: move device sysfs attributes to its own driver."
Next in thread: Guenter Roeck: "Re: [PATCH v3 5/8] mfd / platform: cros_ec: move device sysfs attributes to its own driver."
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