drivers/platform/chrome/cros_ec_lightbar.c - third_party/kernel - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 // Expose the Chromebook Pixel lightbar to userspace
 //
 // Copyright (C) 2014 Google, Inc.

 #include <linux/ctype.h>
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/fs.h>
 #include <linux/kobject.h>
 #include <linux/mfd/cros_ec.h>
 #include <linux/module.h>
 #include <linux/platform_data/cros_ec_commands.h>
 #include <linux/platform_data/cros_ec_proto.h>
 #include <linux/platform_device.h>
 #include <linux/sched.h>
 #include <linux/types.h>
 #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;

 /*
  * Whether or not we have given userspace control of the lightbar.
  * If this is true, we won't do anything during suspend/resume.
  */
 static bool userspace_control;

 static ssize_t interval_msec_show(struct device *dev,
 				  struct device_attribute *attr, char *buf)
 {
 	unsigned long msec = lb_interval_jiffies * 1000 / HZ;

 	return scnprintf(buf, PAGE_SIZE, "%lu\n", msec);
 }

 static ssize_t interval_msec_store(struct device *dev,
 				   struct device_attribute *attr,
 				   const char *buf, size_t count)
 {
 	unsigned long msec;

 	if (kstrtoul(buf, 0, &msec))
 		return -EINVAL;

 	lb_interval_jiffies = msec * HZ / 1000;

 	return count;
 }

 static DEFINE_MUTEX(lb_mutex);
 /* Return 0 if able to throttle correctly, error otherwise */
 static int lb_throttle(void)
 {
 	static unsigned long last_access;
 	unsigned long now, next_timeslot;
 	long delay;
 	int ret = 0;

 	mutex_lock(&lb_mutex);

 	now = jiffies;
 	next_timeslot = last_access + lb_interval_jiffies;

 	if (time_before(now, next_timeslot)) {
 		delay = (long)(next_timeslot) - (long)now;
 		set_current_state(TASK_INTERRUPTIBLE);
 		if (schedule_timeout(delay) > 0) {
 			/* interrupted - just abort */
 			ret = -EINTR;
 			goto out;
 		}
 		now = jiffies;
 	}

 	last_access = now;
 out:
 	mutex_unlock(&lb_mutex);

 	return ret;
 }

 static struct cros_ec_command *alloc_lightbar_cmd_msg(struct cros_ec_dev *ec)
 {
 	struct cros_ec_command *msg;
 	int len;

 	len = max(sizeof(struct ec_params_lightbar),
 		  sizeof(struct ec_response_lightbar));

 	msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
 	if (!msg)
 		return NULL;

 	msg->version = 0;
 	msg->command = EC_CMD_LIGHTBAR_CMD + ec->cmd_offset;
 	msg->outsize = sizeof(struct ec_params_lightbar);
 	msg->insize = sizeof(struct ec_response_lightbar);

 	return msg;
 }

 static int get_lightbar_version(struct cros_ec_dev *ec,
 				uint32_t *ver_ptr, uint32_t *flg_ptr)
 {
 	struct ec_params_lightbar *param;
 	struct ec_response_lightbar *resp;
 	struct cros_ec_command *msg;
 	int ret;

 	msg = alloc_lightbar_cmd_msg(ec);
 	if (!msg)
 		return 0;

 	param = (struct ec_params_lightbar *)msg->data;
 	param->cmd = LIGHTBAR_CMD_VERSION;
 	ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
 	if (ret < 0) {
 		ret = 0;
 		goto exit;
 	}

 	switch (msg->result) {
 	case EC_RES_INVALID_PARAM:
 		/* Pixel had no version command. */
 		if (ver_ptr)
 			*ver_ptr = 0;
 		if (flg_ptr)
 			*flg_ptr = 0;
 		ret = 1;
 		goto exit;

 	case EC_RES_SUCCESS:
 		resp = (struct ec_response_lightbar *)msg->data;

 		/* Future devices w/lightbars should implement this command */
 		if (ver_ptr)
 			*ver_ptr = resp->version.num;
 		if (flg_ptr)
 			*flg_ptr = resp->version.flags;
 		ret = 1;
 		goto exit;
 	}

 	/* Anything else (ie, EC_RES_INVALID_COMMAND) - no lightbar */
 	ret = 0;
 exit:
 	kfree(msg);
 	return ret;
 }

 static ssize_t version_show(struct device *dev,
 			    struct device_attribute *attr, char *buf)
 {
 	uint32_t version = 0, flags = 0;
 	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
 	int ret;

 	ret = lb_throttle();
 	if (ret)
 		return ret;

 	/* This should always succeed, because we check during init. */
 	if (!get_lightbar_version(ec, &version, &flags))
 		return -EIO;

 	return scnprintf(buf, PAGE_SIZE, "%d %d\n", version, flags);
 }

 static ssize_t brightness_store(struct device *dev,
 				struct device_attribute *attr,
 				const char *buf, size_t count)
 {
 	struct ec_params_lightbar *param;
 	struct cros_ec_command *msg;
 	int ret;
 	unsigned int val;
 	struct cros_ec_dev *ec = to_cros_ec_dev(dev);

 	if (kstrtouint(buf, 0, &val))
 		return -EINVAL;

 	msg = alloc_lightbar_cmd_msg(ec);
 	if (!msg)
 		return -ENOMEM;

 	param = (struct ec_params_lightbar *)msg->data;
 	param->cmd = LIGHTBAR_CMD_SET_BRIGHTNESS;
 	param->set_brightness.num = val;
 	ret = lb_throttle();
 	if (ret)
 		goto exit;

 	ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
 	if (ret < 0)
 		goto exit;

 	if (msg->result != EC_RES_SUCCESS) {
 		ret = -EINVAL;
 		goto exit;
 	}

 	ret = count;
 exit:
 	kfree(msg);
 	return ret;
 }


 /*
  * We expect numbers, and we'll keep reading until we find them, skipping over
  * any whitespace (sysfs guarantees that the input is null-terminated). Every
  * four numbers are sent to the lightbar as <LED,R,G,B>. We fail at the first
  * parsing error, if we don't parse any numbers, or if we have numbers left
  * over.
  */
 static ssize_t led_rgb_store(struct device *dev, struct device_attribute *attr,
 			     const char *buf, size_t count)
 {
 	struct ec_params_lightbar *param;
 	struct cros_ec_command *msg;
 	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
 	unsigned int val[4];
 	int ret, i = 0, j = 0, ok = 0;

 	msg = alloc_lightbar_cmd_msg(ec);
 	if (!msg)
 		return -ENOMEM;

 	do {
 		/* Skip any whitespace */
 		while (*buf && isspace(*buf))
 			buf++;

 		if (!*buf)
 			break;

 		ret = sscanf(buf, "%i", &val[i++]);
 		if (ret == 0)
 			goto exit;

 		if (i == 4) {
 			param = (struct ec_params_lightbar *)msg->data;
 			param->cmd = LIGHTBAR_CMD_SET_RGB;
 			param->set_rgb.led = val[0];
 			param->set_rgb.red = val[1];
 			param->set_rgb.green = val[2];
 			param->set_rgb.blue = val[3];
 			/*
 			 * Throttle only the first of every four transactions,
 			 * so that the user can update all four LEDs at once.
 			 */
 			if ((j++ % 4) == 0) {
 				ret = lb_throttle();
 				if (ret)
 					goto exit;
 			}

 			ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
 			if (ret < 0)
 				goto exit;

 			if (msg->result != EC_RES_SUCCESS)
 				goto exit;

 			i = 0;
 			ok = 1;
 		}

 		/* Skip over the number we just read */
 		while (*buf && !isspace(*buf))
 			buf++;

 	} while (*buf);

 exit:
 	kfree(msg);
 	return (ok && i == 0) ? count : -EINVAL;
 }

 static char const *seqname[] = {
 	"ERROR", "S5", "S3", "S0", "S5S3", "S3S0",
 	"S0S3", "S3S5", "STOP", "RUN", "KONAMI",
 	"TAP", "PROGRAM",
 };

 static ssize_t sequence_show(struct device *dev,
 			     struct device_attribute *attr, char *buf)
 {
 	struct ec_params_lightbar *param;
 	struct ec_response_lightbar *resp;
 	struct cros_ec_command *msg;
 	int ret;
 	struct cros_ec_dev *ec = to_cros_ec_dev(dev);

 	msg = alloc_lightbar_cmd_msg(ec);
 	if (!msg)
 		return -ENOMEM;

 	param = (struct ec_params_lightbar *)msg->data;
 	param->cmd = LIGHTBAR_CMD_GET_SEQ;
 	ret = lb_throttle();
 	if (ret)
 		goto exit;

 	ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
 	if (ret < 0)
 		goto exit;

 	if (msg->result != EC_RES_SUCCESS) {
 		ret = scnprintf(buf, PAGE_SIZE,
 				"ERROR: EC returned %d\n", msg->result);
 		goto exit;
 	}

 	resp = (struct ec_response_lightbar *)msg->data;
 	if (resp->get_seq.num >= ARRAY_SIZE(seqname))
 		ret = scnprintf(buf, PAGE_SIZE, "%d\n", resp->get_seq.num);
 	else
 		ret = scnprintf(buf, PAGE_SIZE, "%s\n",
 				seqname[resp->get_seq.num]);

 exit:
 	kfree(msg);
 	return ret;
 }

 static int lb_send_empty_cmd(struct cros_ec_dev *ec, uint8_t cmd)
 {
 	struct ec_params_lightbar *param;
 	struct cros_ec_command *msg;
 	int ret;

 	msg = alloc_lightbar_cmd_msg(ec);
 	if (!msg)
 		return -ENOMEM;

 	param = (struct ec_params_lightbar *)msg->data;
 	param->cmd = cmd;

 	ret = lb_throttle();
 	if (ret)
 		goto error;

 	ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
 	if (ret < 0)
 		goto error;
 	if (msg->result != EC_RES_SUCCESS) {
 		ret = -EINVAL;
 		goto error;
 	}
 	ret = 0;
 error:
 	kfree(msg);

 	return ret;
 }

 static int lb_manual_suspend_ctrl(struct cros_ec_dev *ec, uint8_t enable)
 {
 	struct ec_params_lightbar *param;
 	struct cros_ec_command *msg;
 	int ret;

 	msg = alloc_lightbar_cmd_msg(ec);
 	if (!msg)
 		return -ENOMEM;

 	param = (struct ec_params_lightbar *)msg->data;

 	param->cmd = LIGHTBAR_CMD_MANUAL_SUSPEND_CTRL;
 	param->manual_suspend_ctrl.enable = enable;

 	ret = lb_throttle();
 	if (ret)
 		goto error;

 	ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
 	if (ret < 0)
 		goto error;
 	if (msg->result != EC_RES_SUCCESS) {
 		ret = -EINVAL;
 		goto error;
 	}
 	ret = 0;
 error:
 	kfree(msg);

 	return ret;
 }

 static ssize_t sequence_store(struct device *dev, struct device_attribute *attr,
 			      const char *buf, size_t count)
 {
 	struct ec_params_lightbar *param;
 	struct cros_ec_command *msg;
 	unsigned int num;
 	int ret, len;
 	struct cros_ec_dev *ec = to_cros_ec_dev(dev);

 	for (len = 0; len < count; len++)
 		if (!isalnum(buf[len]))
 			break;

 	for (num = 0; num < ARRAY_SIZE(seqname); num++)
 		if (!strncasecmp(seqname[num], buf, len))
 			break;

 	if (num >= ARRAY_SIZE(seqname)) {
 		ret = kstrtouint(buf, 0, &num);
 		if (ret)
 			return ret;
 	}

 	msg = alloc_lightbar_cmd_msg(ec);
 	if (!msg)
 		return -ENOMEM;

 	param = (struct ec_params_lightbar *)msg->data;
 	param->cmd = LIGHTBAR_CMD_SEQ;
 	param->seq.num = num;
 	ret = lb_throttle();
 	if (ret)
 		goto exit;

 	ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
 	if (ret < 0)
 		goto exit;

 	if (msg->result != EC_RES_SUCCESS) {
 		ret = -EINVAL;
 		goto exit;
 	}

 	ret = count;
 exit:
 	kfree(msg);
 	return ret;
 }

 static ssize_t program_store(struct device *dev, struct device_attribute *attr,
 			     const char *buf, size_t count)
 {
 	int extra_bytes, max_size, ret;
 	struct ec_params_lightbar *param;
 	struct cros_ec_command *msg;
 	struct cros_ec_dev *ec = to_cros_ec_dev(dev);

 	/*
 	 * We might need to reject the program for size reasons. The EC
 	 * enforces a maximum program size, but we also don't want to try
 	 * and send a program that is too big for the protocol. In order
 	 * to ensure the latter, we also need to ensure we have extra bytes
 	 * to represent the rest of the packet.
 	 */
 	extra_bytes = sizeof(*param) - sizeof(param->set_program.data);
 	max_size = min(EC_LB_PROG_LEN, ec->ec_dev->max_request - extra_bytes);
 	if (count > max_size) {
 		dev_err(dev, "Program is %u bytes, too long to send (max: %u)",
 			(unsigned int)count, max_size);

 		return -EINVAL;
 	}

 	msg = alloc_lightbar_cmd_msg(ec);
 	if (!msg)
 		return -ENOMEM;

 	ret = lb_throttle();
 	if (ret)
 		goto exit;

 	dev_info(dev, "Copying %zu byte program to EC", count);

 	param = (struct ec_params_lightbar *)msg->data;
 	param->cmd = LIGHTBAR_CMD_SET_PROGRAM;

 	param->set_program.size = count;
 	memcpy(param->set_program.data, buf, count);

 	/*
 	 * We need to set the message size manually or else it will use
 	 * EC_LB_PROG_LEN. This might be too long, and the program
 	 * is unlikely to use all of the space.
 	 */
 	msg->outsize = count + extra_bytes;

 	ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
 	if (ret < 0)
 		goto exit;
 	if (msg->result != EC_RES_SUCCESS) {
 		ret = -EINVAL;
 		goto exit;
 	}

 	ret = count;
 exit:
 	kfree(msg);

 	return ret;
 }

 static ssize_t userspace_control_show(struct device *dev,
 				      struct device_attribute *attr,
 				      char *buf)
 {
 	return scnprintf(buf, PAGE_SIZE, "%d\n", userspace_control);
 }

 static ssize_t userspace_control_store(struct device *dev,
 				       struct device_attribute *attr,
 				       const char *buf,
 				       size_t count)
 {
 	bool enable;
 	int ret;

 	ret = strtobool(buf, &enable);
 	if (ret < 0)
 		return ret;

 	userspace_control = enable;

 	return count;
 }

 /* Module initialization */

 static DEVICE_ATTR_RW(interval_msec);
 static DEVICE_ATTR_RO(version);
 static DEVICE_ATTR_WO(brightness);
 static DEVICE_ATTR_WO(led_rgb);
 static DEVICE_ATTR_RW(sequence);
 static DEVICE_ATTR_WO(program);
 static DEVICE_ATTR_RW(userspace_control);

 static struct attribute *__lb_cmds_attrs[] = {
 	&dev_attr_interval_msec.attr,
 	&dev_attr_version.attr,
 	&dev_attr_brightness.attr,
 	&dev_attr_led_rgb.attr,
 	&dev_attr_sequence.attr,
 	&dev_attr_program.attr,
 	&dev_attr_userspace_control.attr,
 	NULL,
 };

 static struct attribute_group cros_ec_lightbar_attr_group = {
 	.name = "lightbar",
 	.attrs = __lb_cmds_attrs,
 };

 static int cros_ec_lightbar_probe(struct platform_device *pd)
 {
 	struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
 	struct cros_ec_platform *pdata = dev_get_platdata(ec_dev->dev);
 	struct device *dev = &pd->dev;
 	int ret;

 	/*
 	 * Only instantiate the lightbar if the EC name is 'cros_ec'. Other EC
 	 * devices like 'cros_pd' doesn't have a lightbar.
 	 */
 	if (strcmp(pdata->ec_name, CROS_EC_DEV_NAME) != 0)
 		return -ENODEV;

 	/*
 	 * Ask then for the lightbar version, if it's 0 then the 'cros_ec'
 	 * doesn't have a lightbar.
 	 */
 	if (!get_lightbar_version(ec_dev, NULL, NULL))
 		return -ENODEV;

 	/* 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->parent);

 	if (userspace_control)
 		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->parent);

 	if (userspace_control)
 		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);
	// SPDX-License-Identifier: GPL-2.0+
	// Expose the Chromebook Pixel lightbar to userspace
	//
	// Copyright (C) 2014 Google, Inc.

	#include <linux/ctype.h>
	#include <linux/delay.h>
	#include <linux/device.h>
	#include <linux/fs.h>
	#include <linux/kobject.h>
	#include <linux/mfd/cros_ec.h>
	#include <linux/module.h>
	#include <linux/platform_data/cros_ec_commands.h>
	#include <linux/platform_data/cros_ec_proto.h>
	#include <linux/platform_device.h>
	#include <linux/sched.h>
	#include <linux/types.h>
	#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;

	/*
	* Whether or not we have given userspace control of the lightbar.
	* If this is true, we won't do anything during suspend/resume.
	*/
	static bool userspace_control;

	static ssize_t interval_msec_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	unsigned long msec = lb_interval_jiffies * 1000 / HZ;

	return scnprintf(buf, PAGE_SIZE, "%lu\n", msec);
	}

	static ssize_t interval_msec_store(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t count)
	{
	unsigned long msec;

	if (kstrtoul(buf, 0, &msec))
	return -EINVAL;

	lb_interval_jiffies = msec * HZ / 1000;

	return count;
	}

	static DEFINE_MUTEX(lb_mutex);
	/* Return 0 if able to throttle correctly, error otherwise */
	static int lb_throttle(void)
	{
	static unsigned long last_access;
	unsigned long now, next_timeslot;
	long delay;
	int ret = 0;

	mutex_lock(&lb_mutex);

	now = jiffies;
	next_timeslot = last_access + lb_interval_jiffies;

	if (time_before(now, next_timeslot)) {
	delay = (long)(next_timeslot) - (long)now;
	set_current_state(TASK_INTERRUPTIBLE);
	if (schedule_timeout(delay) > 0) {
	/* interrupted - just abort */
	ret = -EINTR;
	goto out;
	}
	now = jiffies;
	}

	last_access = now;
	out:
	mutex_unlock(&lb_mutex);

	return ret;
	}

	static struct cros_ec_command alloc_lightbar_cmd_msg(struct cros_ec_dev ec)
	{
	struct cros_ec_command *msg;
	int len;

	len = max(sizeof(struct ec_params_lightbar),
	sizeof(struct ec_response_lightbar));

	msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
	if (!msg)
	return NULL;

	msg->version = 0;
	msg->command = EC_CMD_LIGHTBAR_CMD + ec->cmd_offset;
	msg->outsize = sizeof(struct ec_params_lightbar);
	msg->insize = sizeof(struct ec_response_lightbar);

	return msg;
	}

	static int get_lightbar_version(struct cros_ec_dev *ec,
	uint32_t ver_ptr, uint32_t flg_ptr)
	{
	struct ec_params_lightbar *param;
	struct ec_response_lightbar *resp;
	struct cros_ec_command *msg;
	int ret;

	msg = alloc_lightbar_cmd_msg(ec);
	if (!msg)
	return 0;

	param = (struct ec_params_lightbar *)msg->data;
	param->cmd = LIGHTBAR_CMD_VERSION;
	ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
	if (ret < 0) {
	ret = 0;
	goto exit;
	}

	switch (msg->result) {
	case EC_RES_INVALID_PARAM:
	/* Pixel had no version command. */
	if (ver_ptr)
	*ver_ptr = 0;
	if (flg_ptr)
	*flg_ptr = 0;
	ret = 1;
	goto exit;

	case EC_RES_SUCCESS:
	resp = (struct ec_response_lightbar *)msg->data;

	/* Future devices w/lightbars should implement this command */
	if (ver_ptr)
	*ver_ptr = resp->version.num;
	if (flg_ptr)
	*flg_ptr = resp->version.flags;
	ret = 1;
	goto exit;
	}

	/* Anything else (ie, EC_RES_INVALID_COMMAND) - no lightbar */
	ret = 0;
	exit:
	kfree(msg);
	return ret;
	}

	static ssize_t version_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	uint32_t version = 0, flags = 0;
	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
	int ret;

	ret = lb_throttle();
	if (ret)
	return ret;

	/* This should always succeed, because we check during init. */
	if (!get_lightbar_version(ec, &version, &flags))
	return -EIO;

	return scnprintf(buf, PAGE_SIZE, "%d %d\n", version, flags);
	}

	static ssize_t brightness_store(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t count)
	{
	struct ec_params_lightbar *param;
	struct cros_ec_command *msg;
	int ret;
	unsigned int val;
	struct cros_ec_dev *ec = to_cros_ec_dev(dev);

	if (kstrtouint(buf, 0, &val))
	return -EINVAL;

	msg = alloc_lightbar_cmd_msg(ec);
	if (!msg)
	return -ENOMEM;

	param = (struct ec_params_lightbar *)msg->data;
	param->cmd = LIGHTBAR_CMD_SET_BRIGHTNESS;
	param->set_brightness.num = val;
	ret = lb_throttle();
	if (ret)
	goto exit;

	ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
	if (ret < 0)
	goto exit;

	if (msg->result != EC_RES_SUCCESS) {
	ret = -EINVAL;
	goto exit;
	}

	ret = count;
	exit:
	kfree(msg);
	return ret;
	}


	/*
	* We expect numbers, and we'll keep reading until we find them, skipping over
	* any whitespace (sysfs guarantees that the input is null-terminated). Every
	* four numbers are sent to the lightbar as <LED,R,G,B>. We fail at the first
	* parsing error, if we don't parse any numbers, or if we have numbers left
	* over.
	*/
	static ssize_t led_rgb_store(struct device dev, struct device_attribute attr,
	const char *buf, size_t count)
	{
	struct ec_params_lightbar *param;
	struct cros_ec_command *msg;
	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
	unsigned int val[4];
	int ret, i = 0, j = 0, ok = 0;

	msg = alloc_lightbar_cmd_msg(ec);
	if (!msg)
	return -ENOMEM;

	do {
	/* Skip any whitespace */
	while (buf && isspace(buf))
	buf++;

	if (!*buf)
	break;

	ret = sscanf(buf, "%i", &val[i++]);
	if (ret == 0)
	goto exit;

	if (i == 4) {
	param = (struct ec_params_lightbar *)msg->data;
	param->cmd = LIGHTBAR_CMD_SET_RGB;
	param->set_rgb.led = val[0];
	param->set_rgb.red = val[1];
	param->set_rgb.green = val[2];
	param->set_rgb.blue = val[3];
	/*
	* Throttle only the first of every four transactions,
	* so that the user can update all four LEDs at once.
	*/
	if ((j++ % 4) == 0) {
	ret = lb_throttle();
	if (ret)
	goto exit;
	}

	ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
	if (ret < 0)
	goto exit;

	if (msg->result != EC_RES_SUCCESS)
	goto exit;

	i = 0;
	ok = 1;
	}

	/* Skip over the number we just read */
	while (buf && !isspace(buf))
	buf++;

	} while (*buf);

	exit:
	kfree(msg);
	return (ok && i == 0) ? count : -EINVAL;
	}

	static char const *seqname[] = {
	"ERROR", "S5", "S3", "S0", "S5S3", "S3S0",
	"S0S3", "S3S5", "STOP", "RUN", "KONAMI",
	"TAP", "PROGRAM",
	};

	static ssize_t sequence_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct ec_params_lightbar *param;
	struct ec_response_lightbar *resp;
	struct cros_ec_command *msg;
	int ret;
	struct cros_ec_dev *ec = to_cros_ec_dev(dev);

	msg = alloc_lightbar_cmd_msg(ec);
	if (!msg)
	return -ENOMEM;

	param = (struct ec_params_lightbar *)msg->data;
	param->cmd = LIGHTBAR_CMD_GET_SEQ;
	ret = lb_throttle();
	if (ret)
	goto exit;

	ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
	if (ret < 0)
	goto exit;

	if (msg->result != EC_RES_SUCCESS) {
	ret = scnprintf(buf, PAGE_SIZE,
	"ERROR: EC returned %d\n", msg->result);
	goto exit;
	}

	resp = (struct ec_response_lightbar *)msg->data;
	if (resp->get_seq.num >= ARRAY_SIZE(seqname))
	ret = scnprintf(buf, PAGE_SIZE, "%d\n", resp->get_seq.num);
	else
	ret = scnprintf(buf, PAGE_SIZE, "%s\n",
	seqname[resp->get_seq.num]);

	exit:
	kfree(msg);
	return ret;
	}

	static int lb_send_empty_cmd(struct cros_ec_dev *ec, uint8_t cmd)
	{
	struct ec_params_lightbar *param;
	struct cros_ec_command *msg;
	int ret;

	msg = alloc_lightbar_cmd_msg(ec);
	if (!msg)
	return -ENOMEM;

	param = (struct ec_params_lightbar *)msg->data;
	param->cmd = cmd;

	ret = lb_throttle();
	if (ret)
	goto error;

	ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
	if (ret < 0)
	goto error;
	if (msg->result != EC_RES_SUCCESS) {
	ret = -EINVAL;
	goto error;
	}
	ret = 0;
	error:
	kfree(msg);

	return ret;
	}

	static int lb_manual_suspend_ctrl(struct cros_ec_dev *ec, uint8_t enable)
	{
	struct ec_params_lightbar *param;
	struct cros_ec_command *msg;
	int ret;

	msg = alloc_lightbar_cmd_msg(ec);
	if (!msg)
	return -ENOMEM;

	param = (struct ec_params_lightbar *)msg->data;

	param->cmd = LIGHTBAR_CMD_MANUAL_SUSPEND_CTRL;
	param->manual_suspend_ctrl.enable = enable;

	ret = lb_throttle();
	if (ret)
	goto error;

	ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
	if (ret < 0)
	goto error;
	if (msg->result != EC_RES_SUCCESS) {
	ret = -EINVAL;
	goto error;
	}
	ret = 0;
	error:
	kfree(msg);

	return ret;
	}

	static ssize_t sequence_store(struct device dev, struct device_attribute attr,
	const char *buf, size_t count)
	{
	struct ec_params_lightbar *param;
	struct cros_ec_command *msg;
	unsigned int num;
	int ret, len;
	struct cros_ec_dev *ec = to_cros_ec_dev(dev);

	for (len = 0; len < count; len++)
	if (!isalnum(buf[len]))
	break;

	for (num = 0; num < ARRAY_SIZE(seqname); num++)
	if (!strncasecmp(seqname[num], buf, len))
	break;

	if (num >= ARRAY_SIZE(seqname)) {
	ret = kstrtouint(buf, 0, &num);
	if (ret)
	return ret;
	}

	msg = alloc_lightbar_cmd_msg(ec);
	if (!msg)
	return -ENOMEM;

	param = (struct ec_params_lightbar *)msg->data;
	param->cmd = LIGHTBAR_CMD_SEQ;
	param->seq.num = num;
	ret = lb_throttle();
	if (ret)
	goto exit;

	ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
	if (ret < 0)
	goto exit;

	if (msg->result != EC_RES_SUCCESS) {
	ret = -EINVAL;
	goto exit;
	}

	ret = count;
	exit:
	kfree(msg);
	return ret;
	}

	static ssize_t program_store(struct device dev, struct device_attribute attr,
	const char *buf, size_t count)
	{
	int extra_bytes, max_size, ret;
	struct ec_params_lightbar *param;
	struct cros_ec_command *msg;
	struct cros_ec_dev *ec = to_cros_ec_dev(dev);

	/*
	* We might need to reject the program for size reasons. The EC
	* enforces a maximum program size, but we also don't want to try
	* and send a program that is too big for the protocol. In order
	* to ensure the latter, we also need to ensure we have extra bytes
	* to represent the rest of the packet.
	*/
	extra_bytes = sizeof(*param) - sizeof(param->set_program.data);
	max_size = min(EC_LB_PROG_LEN, ec->ec_dev->max_request - extra_bytes);
	if (count > max_size) {
	dev_err(dev, "Program is %u bytes, too long to send (max: %u)",
	(unsigned int)count, max_size);

	return -EINVAL;
	}

	msg = alloc_lightbar_cmd_msg(ec);
	if (!msg)
	return -ENOMEM;

	ret = lb_throttle();
	if (ret)
	goto exit;

	dev_info(dev, "Copying %zu byte program to EC", count);

	param = (struct ec_params_lightbar *)msg->data;
	param->cmd = LIGHTBAR_CMD_SET_PROGRAM;

	param->set_program.size = count;
	memcpy(param->set_program.data, buf, count);

	/*
	* We need to set the message size manually or else it will use
	* EC_LB_PROG_LEN. This might be too long, and the program
	* is unlikely to use all of the space.
	*/
	msg->outsize = count + extra_bytes;

	ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
	if (ret < 0)
	goto exit;
	if (msg->result != EC_RES_SUCCESS) {
	ret = -EINVAL;
	goto exit;
	}

	ret = count;
	exit:
	kfree(msg);

	return ret;
	}

	static ssize_t userspace_control_show(struct device *dev,
	struct device_attribute *attr,
	char *buf)
	{
	return scnprintf(buf, PAGE_SIZE, "%d\n", userspace_control);
	}

	static ssize_t userspace_control_store(struct device *dev,
	struct device_attribute *attr,
	const char *buf,
	size_t count)
	{
	bool enable;
	int ret;

	ret = strtobool(buf, &enable);
	if (ret < 0)
	return ret;

	userspace_control = enable;

	return count;
	}

	/* Module initialization */

	static DEVICE_ATTR_RW(interval_msec);
	static DEVICE_ATTR_RO(version);
	static DEVICE_ATTR_WO(brightness);
	static DEVICE_ATTR_WO(led_rgb);
	static DEVICE_ATTR_RW(sequence);
	static DEVICE_ATTR_WO(program);
	static DEVICE_ATTR_RW(userspace_control);

	static struct attribute *__lb_cmds_attrs[] = {
	&dev_attr_interval_msec.attr,
	&dev_attr_version.attr,
	&dev_attr_brightness.attr,
	&dev_attr_led_rgb.attr,
	&dev_attr_sequence.attr,
	&dev_attr_program.attr,
	&dev_attr_userspace_control.attr,
	NULL,
	};

	static struct attribute_group cros_ec_lightbar_attr_group = {
	.name = "lightbar",
	.attrs = __lb_cmds_attrs,
	};

	static int cros_ec_lightbar_probe(struct platform_device *pd)
	{
	struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
	struct cros_ec_platform *pdata = dev_get_platdata(ec_dev->dev);
	struct device *dev = &pd->dev;
	int ret;

	/*
	* Only instantiate the lightbar if the EC name is 'cros_ec'. Other EC
	* devices like 'cros_pd' doesn't have a lightbar.
	*/
	if (strcmp(pdata->ec_name, CROS_EC_DEV_NAME) != 0)
	return -ENODEV;

	/*
	* Ask then for the lightbar version, if it's 0 then the 'cros_ec'
	* doesn't have a lightbar.
	*/
	if (!get_lightbar_version(ec_dev, NULL, NULL))
	return -ENODEV;

	/* 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->parent);

	if (userspace_control)
	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->parent);

	if (userspace_control)
	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);