Re: [PATCH v3 2/8] mfd / platform: cros_ec: move lightbar attributes to its own driver.

[Guenter Roeck]

On Tue, Nov 27, 2018 at 4:19 AM Enric Balletbo i Serra
<enric.balletbo@xxxxxxxxxxxxx> wrote:
>
> The entire way how cros sysfs attibutes are created is broken.
> cros_ec_lightbar should be its own driver and its attributes should be
> associated with a lightbar driver not the mfd driver. In order to retain
> the path, the lightbar attributes are attached to the cros_class.
>
> The patch also adds the sysfs documentation.
>
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>

Reviewed-by: Guenter Roeck <groeck@xxxxxxxxxxxx>

> ---
>
> Changes in v3:
> - Removed unneded check for ec_dev.
>
> Changes in v2:
> - Removed the two exported functions to attach/detach to the cros_class.
> - Use dev_warn instead of dev_err when adding the lightbar.
>
>  ...sfs-class-chromeos-driver-cros-ec-lightbar | 74 +++++++++++++++
>  drivers/mfd/cros_ec_dev.c                     | 24 ++---
>  drivers/mfd/cros_ec_dev.h                     |  6 --
>  drivers/platform/chrome/Kconfig               | 10 ++
>  drivers/platform/chrome/Makefile              |  3 +-
>  drivers/platform/chrome/cros_ec_lightbar.c    | 95 ++++++++++++++-----
>  include/linux/mfd/cros_ec.h                   |  1 -
>  7 files changed, 172 insertions(+), 41 deletions(-)
>  create mode 100644 Documentation/ABI/testing/sysfs-class-chromeos-driver-cros-ec-lightbar
>
> diff --git a/Documentation/ABI/testing/sysfs-class-chromeos-driver-cros-ec-lightbar b/Documentation/ABI/testing/sysfs-class-chromeos-driver-cros-ec-lightbar
> new file mode 100644
> index 000000000000..4893fd2e956f
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-chromeos-driver-cros-ec-lightbar
> @@ -0,0 +1,74 @@
> +What:          /sys/class/chromeos/<cros-ec>/lightbar/brightness
> +Date:          August 2015
> +KernelVersion: 4.2
> +Description:
> +               Writing to this file adjusts the overall brightness of
> +               the lightbar, separate from any color intensity. The
> +               valid range is 0 (off) to 255 (maximum brightness).
> +
> +What:          /sys/class/chromeos/<cros-ec>/lightbar/interval_msec
> +Date:          August 2015
> +KernelVersion: 4.2
> +Description:
> +               The lightbar is controlled by an embedded controller (EC),
> +               which also manages the keyboard, battery charging, fans,
> +               and other system hardware. To prevent unprivileged users
> +               from interfering with the other EC functions, the rate at
> +               which the lightbar control files can be read or written is
> +               limited.
> +
> +               Reading this file will return the number of milliseconds
> +               that must elapse between accessing any of the lightbar
> +               functions through this interface. Going faster will simply
> +               block until the necessary interval has lapsed. The interval
> +               applies uniformly to all accesses of any kind by any user.
> +
> +What:          /sys/class/chromeos/<cros-ec>/lightbar/led_rgb
> +Date:          August 2015
> +KernelVersion: 4.2
> +Description:
> +               This allows you to control each LED segment. If the
> +               lightbar is already running one of the automatic
> +               sequences, you probably wonât see anything change because
> +               your color setting will be almost immediately replaced.
> +               To get useful results, you should stop the lightbar
> +               sequence first.
> +
> +               The values written to this file are sets of four integers,
> +               indicating LED, RED, GREEN, BLUE. The LED number is 0 to 3
> +               to select a single segment, or 4 to set all four segments
> +               to the same value at once. The RED, GREEN, and BLUE
> +               numbers should be in the range 0 (off) to 255 (maximum).
> +               You can update more than one segment at a time by writing
> +               more than one set of four integers.
> +
> +What:          /sys/class/chromeos/<cros-ec>/lightbar/program
> +Date:          August 2015
> +KernelVersion: 4.2
> +Description:
> +               This allows you to upload and run custom lightbar sequences.
> +
> +What:          /sys/class/chromeos/<cros-ec>/lightbar/sequence
> +Date:          August 2015
> +KernelVersion: 4.2
> +Description:
> +               The Pixel lightbar has a number of built-in sequences
> +               that it displays under various conditions, such as at
> +               power on, shut down, or while running. Reading from this
> +               file displays the current sequence that the lightbar is
> +               displaying. Writing to this file allows you to change the
> +               sequence.
> +
> +What:          /sys/class/chromeos/<cros-ec>/lightbar/userspace_control
> +Date:          August 2015
> +KernelVersion: 4.2
> +Description:
> +               This allows you to take the control of the lightbar. This
> +               prevents the kernel from going through its normal
> +               sequences.
> +
> +What:          /sys/class/chromeos/<cros-ec>/lightbar/version
> +Date:          August 2015
> +KernelVersion: 4.2
> +Description:
> +               Show the information about the lightbar version.
> diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
> index ff788d3e6d5f..614f888c9d6d 100644
> --- a/drivers/mfd/cros_ec_dev.c
> +++ b/drivers/mfd/cros_ec_dev.c
> @@ -36,7 +36,6 @@ static int ec_major;
>
>  static const struct attribute_group *cros_ec_groups[] = {
>         &cros_ec_attr_group,
> -       &cros_ec_lightbar_attr_group,
>         &cros_ec_vbc_attr_group,
>         NULL,
>  };
> @@ -390,6 +389,10 @@ static const struct mfd_cell cros_usbpd_charger_cells[] = {
>         { .name = "cros-usbpd-charger" }
>  };
>
> +static const struct mfd_cell cros_ec_platform_cells[] = {
> +       { .name = "cros-ec-lightbar" },
> +};
> +
>  static int ec_device_probe(struct platform_device *pdev)
>  {
>         int retval = -ENOMEM;
> @@ -464,9 +467,6 @@ static int ec_device_probe(struct platform_device *pdev)
>                                 retval);
>         }
>
> -       /* Take control of the lightbar from the EC. */
> -       lb_manual_suspend_ctrl(ec, 1);
> -
>         /* We can now add the sysfs class, we know which parameter to show */
>         retval = cdev_device_add(&ec->cdev, &ec->class_dev);
>         if (retval) {
> @@ -474,6 +474,15 @@ static int ec_device_probe(struct platform_device *pdev)
>                 goto failed;
>         }
>
> +       retval = mfd_add_devices(ec->dev, PLATFORM_DEVID_AUTO,
> +                                cros_ec_platform_cells,
> +                                ARRAY_SIZE(cros_ec_platform_cells),
> +                                NULL, 0, NULL);
> +       if (retval)
> +               dev_warn(ec->dev,
> +                        "failed to add cros-ec platform devices: %d\n",
> +                        retval);
> +
>         if (cros_ec_debugfs_init(ec))
>                 dev_warn(dev, "failed to create debugfs directory\n");
>
> @@ -488,9 +497,6 @@ static int ec_device_remove(struct platform_device *pdev)
>  {
>         struct cros_ec_dev *ec = dev_get_drvdata(&pdev->dev);
>
> -       /* Let the EC take over the lightbar again. */
> -       lb_manual_suspend_ctrl(ec, 0);
> -
>         cros_ec_debugfs_remove(ec);
>
>         mfd_remove_devices(ec->dev);
> @@ -519,8 +525,6 @@ static __maybe_unused int ec_device_suspend(struct device *dev)
>
>         cros_ec_debugfs_suspend(ec);
>
> -       lb_suspend(ec);
> -
>         return 0;
>  }
>
> @@ -530,8 +534,6 @@ static __maybe_unused int ec_device_resume(struct device *dev)
>
>         cros_ec_debugfs_resume(ec);
>
> -       lb_resume(ec);
> -
>         return 0;
>  }
>
> diff --git a/drivers/mfd/cros_ec_dev.h b/drivers/mfd/cros_ec_dev.h
> index 978d836a0248..ec750433455a 100644
> --- a/drivers/mfd/cros_ec_dev.h
> +++ b/drivers/mfd/cros_ec_dev.h
> @@ -44,10 +44,4 @@ struct cros_ec_readmem {
>  #define CROS_EC_DEV_IOCXCMD   _IOWR(CROS_EC_DEV_IOC, 0, struct cros_ec_command)
>  #define CROS_EC_DEV_IOCRDMEM  _IOWR(CROS_EC_DEV_IOC, 1, struct cros_ec_readmem)
>
> -/* Lightbar utilities */
> -extern bool ec_has_lightbar(struct cros_ec_dev *ec);
> -extern int lb_manual_suspend_ctrl(struct cros_ec_dev *ec, uint8_t enable);
> -extern int lb_suspend(struct cros_ec_dev *ec);
> -extern int lb_resume(struct cros_ec_dev *ec);
> -
>  #endif /* _CROS_EC_DEV_H_ */
> diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
> index 16b1615958aa..05bcefbe1926 100644
> --- a/drivers/platform/chrome/Kconfig
> +++ b/drivers/platform/chrome/Kconfig
> @@ -111,4 +111,14 @@ config CROS_KBD_LED_BACKLIGHT
>           To compile this driver as a module, choose M here: the
>           module will be called cros_kbd_led_backlight.
>
> +config CROS_EC_LIGHTBAR
> +       tristate "Chromebook Pixel's lightbar support"
> +       depends on MFD_CROS_EC_CHARDEV
> +       help
> +         This option exposes the Chromebook Pixel's lightbar to
> +         userspace.
> +
> +         To compile this driver as a module, choose M here: the
> +         module will be called cros_ec_lightbar.
> +
>  endif # CHROMEOS_PLATFORMS
> diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
> index cd591bf872bb..3c29a4b405d5 100644
> --- a/drivers/platform/chrome/Makefile
> +++ b/drivers/platform/chrome/Makefile
> @@ -3,7 +3,7 @@
>  obj-$(CONFIG_CHROMEOS_LAPTOP)          += chromeos_laptop.o
>  obj-$(CONFIG_CHROMEOS_PSTORE)          += chromeos_pstore.o
>  obj-$(CONFIG_CHROMEOS_TBMC)            += chromeos_tbmc.o
> -cros_ec_ctl-objs                       := cros_ec_sysfs.o cros_ec_lightbar.o \
> +cros_ec_ctl-objs                       := cros_ec_sysfs.o \
>                                            cros_ec_vbc.o cros_ec_debugfs.o
>  obj-$(CONFIG_CROS_EC_CTL)              += cros_ec_ctl.o
>  obj-$(CONFIG_CROS_EC_I2C)              += cros_ec_i2c.o
> @@ -13,3 +13,4 @@ cros_ec_lpcs-$(CONFIG_CROS_EC_LPC_MEC)        += cros_ec_lpc_mec.o
>  obj-$(CONFIG_CROS_EC_LPC)              += cros_ec_lpcs.o
>  obj-$(CONFIG_CROS_EC_PROTO)            += cros_ec_proto.o
>  obj-$(CONFIG_CROS_KBD_LED_BACKLIGHT)   += cros_kbd_led_backlight.o
> +obj-$(CONFIG_CROS_EC_LIGHTBAR)         += cros_ec_lightbar.o
> diff --git a/drivers/platform/chrome/cros_ec_lightbar.c b/drivers/platform/chrome/cros_ec_lightbar.c
> index 68193bb53383..80eed6317570 100644
> --- a/drivers/platform/chrome/cros_ec_lightbar.c
> +++ b/drivers/platform/chrome/cros_ec_lightbar.c
> @@ -33,6 +33,8 @@
>  #include <linux/uaccess.h>
>  #include <linux/slab.h>
>
> +#define DRV_NAME "cros-ec-lightbar"
> +
>  /* Rate-limit the lightbar interface to prevent DoS. */
>  static unsigned long lb_interval_jiffies = 50 * HZ / 1000;
>
> @@ -373,7 +375,7 @@ static int lb_send_empty_cmd(struct cros_ec_dev *ec, uint8_t cmd)
>         return ret;
>  }
>
> -int lb_manual_suspend_ctrl(struct cros_ec_dev *ec, uint8_t enable)
> +static int lb_manual_suspend_ctrl(struct cros_ec_dev *ec, uint8_t enable)
>  {
>         struct ec_params_lightbar *param;
>         struct cros_ec_command *msg;
> @@ -408,25 +410,6 @@ int lb_manual_suspend_ctrl(struct cros_ec_dev *ec, uint8_t enable)
>
>         return ret;
>  }
> -EXPORT_SYMBOL(lb_manual_suspend_ctrl);
> -
> -int lb_suspend(struct cros_ec_dev *ec)
> -{
> -       if (userspace_control || ec != ec_with_lightbar)
> -               return 0;
> -
> -       return lb_send_empty_cmd(ec, LIGHTBAR_CMD_SUSPEND);
> -}
> -EXPORT_SYMBOL(lb_suspend);
> -
> -int lb_resume(struct cros_ec_dev *ec)
> -{
> -       if (userspace_control || ec != ec_with_lightbar)
> -               return 0;
> -
> -       return lb_send_empty_cmd(ec, LIGHTBAR_CMD_RESUME);
> -}
> -EXPORT_SYMBOL(lb_resume);
>
>  static ssize_t sequence_store(struct device *dev, struct device_attribute *attr,
>                               const char *buf, size_t count)
> @@ -584,7 +567,7 @@ static struct attribute *__lb_cmds_attrs[] = {
>         NULL,
>  };
>
> -bool ec_has_lightbar(struct cros_ec_dev *ec)
> +static bool ec_has_lightbar(struct cros_ec_dev *ec)
>  {
>         return !!get_lightbar_version(ec, NULL, NULL);
>  }
> @@ -616,4 +599,72 @@ struct attribute_group cros_ec_lightbar_attr_group = {
>         .attrs = __lb_cmds_attrs,
>         .is_visible = cros_ec_lightbar_attrs_are_visible,
>  };
> -EXPORT_SYMBOL(cros_ec_lightbar_attr_group);
> +
> +static int cros_ec_lightbar_probe(struct platform_device *pd)
> +{
> +       struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
> +       struct device *dev = &pd->dev;
> +       int ret;
> +
> +       /* Take control of the lightbar from the EC. */
> +       lb_manual_suspend_ctrl(ec_dev, 1);
> +
> +       ret = sysfs_create_group(&ec_dev->class_dev.kobj,
> +                                &cros_ec_lightbar_attr_group);
> +       if (ret < 0)
> +               dev_err(dev, "failed to create %s attributes. err=%d\n",
> +                       cros_ec_lightbar_attr_group.name, ret);
> +
> +       return ret;
> +}
> +
> +static int cros_ec_lightbar_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_lightbar_attr_group);
> +
> +       /* Let the EC take over the lightbar again. */
> +       lb_manual_suspend_ctrl(ec_dev, 0);
> +
> +       return 0;
> +}
> +
> +static int __maybe_unused cros_ec_lightbar_resume(struct device *dev)
> +{
> +       struct cros_ec_dev *ec_dev = dev_get_drvdata(dev);
> +
> +       if (userspace_control || ec_dev != ec_with_lightbar)
> +               return 0;
> +
> +       return lb_send_empty_cmd(ec_dev, LIGHTBAR_CMD_RESUME);
> +}
> +
> +static int __maybe_unused cros_ec_lightbar_suspend(struct device *dev)
> +{
> +       struct cros_ec_dev *ec_dev = dev_get_drvdata(dev);
> +
> +       if (userspace_control || ec_dev != ec_with_lightbar)
> +               return 0;
> +
> +       return lb_send_empty_cmd(ec_dev, LIGHTBAR_CMD_SUSPEND);
> +}
> +
> +static SIMPLE_DEV_PM_OPS(cros_ec_lightbar_pm_ops,
> +                        cros_ec_lightbar_suspend, cros_ec_lightbar_resume);
> +
> +static struct platform_driver cros_ec_lightbar_driver = {
> +       .driver = {
> +               .name = DRV_NAME,
> +               .pm = &cros_ec_lightbar_pm_ops,
> +       },
> +       .probe = cros_ec_lightbar_probe,
> +       .remove = cros_ec_lightbar_remove,
> +};
> +
> +module_platform_driver(cros_ec_lightbar_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Expose the Chromebook Pixel's lightbar to userspace");
> +MODULE_ALIAS("platform:" DRV_NAME);
> diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> index 706dd724de52..b6beba3031ba 100644
> --- a/include/linux/mfd/cros_ec.h
> +++ b/include/linux/mfd/cros_ec.h
> @@ -325,7 +325,6 @@ u32 cros_ec_get_host_event(struct cros_ec_device *ec_dev);
>
>  /* sysfs stuff */
>  extern struct attribute_group cros_ec_attr_group;
> -extern struct attribute_group cros_ec_lightbar_attr_group;
>  extern struct attribute_group cros_ec_vbc_attr_group;
>
>  /* debugfs stuff */
> --
> 2.19.1
>