mfd / platform: cros_ec: Move lightbar attributes to its own driver

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 <[e-mail]>
Reviewed-by: Guenter Roeck <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>

Documentation/ABI/testing/sysfs-class-chromeos-driver-cros-ec-lightbar

···
+What:		/sys/class/chromeos/<ec-device-name>/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/<ec-device-name>/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/<ec-device-name>/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 won’t 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/<ec-device-name>/lightbar/program
+Date:		August 2015
+KernelVersion:	4.2
+Description:
+		This allows you to upload and run custom lightbar sequences.
+
+What:		/sys/class/chromeos/<ec-device-name>/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/<ec-device-name>/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/<ec-device-name>/lightbar/version
+Date:		August 2015
+KernelVersion:	4.2
+Description:
+		Show the information about the lightbar version.

drivers/mfd/cros_ec_dev.c

···
 
 static const struct attribute_group *cros_ec_groups[] = {
 	&cros_ec_attr_group,
-	&cros_ec_lightbar_attr_group,
 	&cros_ec_vbc_attr_group,
 	NULL,
 };
···
 	{ .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;
···
 				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) {
 		dev_err(dev, "cdev_device_add failed => %d\n", retval);
 		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");
···
 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);
 
···
 
 	cros_ec_debugfs_suspend(ec);
 
-	lb_suspend(ec);
-
 	return 0;
 }
 
···
 	struct cros_ec_dev *ec = dev_get_drvdata(dev);
 
 	cros_ec_debugfs_resume(ec);
-
-	lb_resume(ec);
 
 	return 0;
 }

drivers/mfd/cros_ec_dev.h

···
 #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_ */

drivers/platform/chrome/Kconfig

···
 	  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
+	default 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

drivers/platform/chrome/Makefile

···
 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-$(CONFIG_CROS_EC_I2C)		+= cros_ec_i2c.o
···
 obj-$(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

drivers/platform/chrome/cros_ec_lightbar.c

···
 #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;
 
···
 	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;
···
 
 	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)
···
 	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);
 }
···
 	.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);

include/linux/mfd/cros_ec.h

···
 
 /* 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 */