// 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/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
  ", 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
  ", 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
  ", 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
  ", resp->get_seq.num);

  	else

  		ret = scnprintf(buf, PAGE_SIZE, "%s
  ",
  				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
  ", 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
  ",
  			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);