// SPDX-License-Identifier: GPL-2.0-or-only
/*
 * Deepcool Digital Linux Kernel Driver
 *
 * Driver for Deepcool Digital USB HID devices (CPU coolers, AIOs, cases)
 * Provides sysfs interface for monitoring and controlling display modes
 *
 * Copyright (C) 2025
 */

#include <linux/cpufreq.h>
#include <linux/cpumask.h>
#include <linux/hid.h>
#include <linux/hwmon-sysfs.h>
#include <linux/hwmon.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/thermal.h>
#include <linux/workqueue.h>

#define DRIVER_NAME "deepcool_digital"
#define DRIVER_VERSION "0.1.0"

// Vendor and Product IDs
#define DEEPCOOL_VENDOR_ID 0x3633
#define CH510_VENDOR_ID 0x34D3
#define CH510_PRODUCT_ID 0x1100

// Update intervals
#define DEFAULT_UPDATE_INTERVAL_MS 1000
#define MIN_UPDATE_INTERVAL_MS 100
#define MAX_UPDATE_INTERVAL_MS 2000
#define AUTO_MODE_INTERVAL_MS 5000

// Temperature limits
#define TEMP_WARNING_C 80
#define TEMP_WARNING_F 176
#define TEMP_LIMIT_C 90
#define TEMP_LIMIT_F 194

// Device series identifiers
enum deepcool_series {
  DEEPCOOL_AK_SERIES,
  DEEPCOOL_LS_SERIES,
  DEEPCOOL_AG_SERIES,
  DEEPCOOL_LQ_SERIES,
  DEEPCOOL_LD_SERIES,
  DEEPCOOL_LP_SERIES,
  DEEPCOOL_CH_SERIES,
  DEEPCOOL_CH_SERIES_GEN2,
  DEEPCOOL_CH510,
  DEEPCOOL_AK400_PRO,
  DEEPCOOL_AK620_PRO,
  DEEPCOOL_UNKNOWN,
};

// Display modes
enum deepcool_mode {
  MODE_DEFAULT = 0,
  MODE_AUTO,
  MODE_CPU_TEMP,
  MODE_CPU_USAGE,
  MODE_CPU_POWER,
  MODE_CPU_FREQ,
  MODE_CPU_FAN,
  MODE_GPU_TEMP,
  MODE_GPU_USAGE,
  MODE_GPU_POWER,
  MODE_CPU,
  MODE_GPU,
  MODE_PSU,
  MODE_MAX,
};

// Represents a device
struct deepcool_device {
  struct hid_device *hdev;
  struct device *hwmon_dev;
  struct delayed_work update_work;
  struct mutex lock;

  // Device identification
  enum deepcool_series series;
  u16 product_id;

  // Configuration
  enum deepcool_mode mode;
  enum deepcool_mode secondary_mode;
  unsigned int update_interval_ms;
  bool fahrenheit;
  bool alarm_enabled;
  u8 rotation;

  // CPU monitoring state
  u64 prev_idle_time;
  u64 prev_total_time;
  u64 prev_energy_uj;
  unsigned long prev_jiffies;

  // Cached sensor values
  s32 cpu_temp;
  u8 cpu_usage;
  u16 cpu_power;
  u16 cpu_freq;

  // Auto mode state
  unsigned long auto_mode_last_change;
  enum deepcool_mode auto_mode_current;

  // Device capabilities
  bool supports_secondary_mode;
  bool supports_rotation;
  bool supports_alarm;
  bool supports_fahrenheit;
};

// Map mode names
static const char *mode_names[MODE_MAX] = {
    [MODE_DEFAULT] = "default",
    [MODE_AUTO] = "auto",
    [MODE_CPU_TEMP] = "cpu_temp",
    [MODE_CPU_USAGE] = "cpu_usage",
    [MODE_CPU_POWER] = "cpu_power",
    [MODE_CPU_FREQ] = "cpu_freq",
    [MODE_CPU_FAN] = "cpu_fan",
    [MODE_GPU_TEMP] = "gpu_temp",
    [MODE_GPU_USAGE] = "gpu_usage",
    [MODE_GPU_POWER] = "gpu_power",
    [MODE_CPU] = "cpu",
    [MODE_GPU] = "gpu",
    [MODE_PSU] = "psu",
};

static void deepcool_update_work(struct work_struct *work);
static int deepcool_send_packet(struct deepcool_device *ddata);

// CPU Monitoring

static s32 deepcool_read_cpu_temp(void) {
  struct thermal_zone_device *tz;
  int temp = 0;
  int ret;

  // Try to find CPU thermal zone
  // Keyword: try
  // This sometimes fails unexpectedly and I do not know why
  tz = thermal_zone_get_zone_by_name("x86_pkg_temp");
  if (IS_ERR(tz)) {
    tz = thermal_zone_get_zone_by_name("cpu_thermal");
    if (IS_ERR(tz))
      return 0;
  }

  ret = thermal_zone_get_temp(tz, &temp);
  if (ret < 0)
    return 0;

  return temp / 1000;
}

static void deepcool_read_cpu_usage(struct deepcool_device *ddata) {
  u64 idle_time = 0, total_time = 0;
  u64 delta_idle, delta_total;
  int cpu;

  // Sum up idle and total time across all CPUs
  for_each_possible_cpu(cpu) {
    struct kernel_cpustat *kcs = &kcpustat_cpu(cpu);

    idle_time += kcs->cpustat[CPUTIME_IDLE];
    idle_time += kcs->cpustat[CPUTIME_IOWAIT];

    total_time += kcs->cpustat[CPUTIME_USER];
    total_time += kcs->cpustat[CPUTIME_NICE];
    total_time += kcs->cpustat[CPUTIME_SYSTEM];
    total_time += kcs->cpustat[CPUTIME_IDLE];
    total_time += kcs->cpustat[CPUTIME_IOWAIT];
    total_time += kcs->cpustat[CPUTIME_IRQ];
    total_time += kcs->cpustat[CPUTIME_SOFTIRQ];
    total_time += kcs->cpustat[CPUTIME_STEAL];
  }

  if (ddata->prev_total_time == 0) {
    ddata->prev_idle_time = idle_time;
    ddata->prev_total_time = total_time;
    ddata->cpu_usage = 0;
    return;
  }

  delta_idle = idle_time - ddata->prev_idle_time;
  delta_total = total_time - ddata->prev_total_time;

  if (delta_total > 0)
    ddata->cpu_usage = 100 - (u8)((delta_idle * 100) / delta_total);
  else
    ddata->cpu_usage = 0;

  ddata->prev_idle_time = idle_time;
  ddata->prev_total_time = total_time;
}

static u16 deepcool_read_cpu_freq(void) {
  unsigned int freq_khz = 0;
  unsigned int max_freq = 0;
  int cpu;

  // Find the highest CPU frequency across all cores
  for_each_possible_cpu(cpu) {
    freq_khz = cpufreq_quick_get(cpu);
    if (freq_khz > max_freq)
      max_freq = freq_khz;
  }

  // Convert kHz to MHz
  return max_freq / 1000;
}

static u64 deepcool_read_cpu_energy(void) {
  struct file *fp;
  char buf[64];
  u64 energy = 0;
  loff_t pos = 0;
  int ret;

  // TODO: confirm if this path can change
  fp = filp_open("/sys/class/powercap/intel-rapl/intel-rapl:0/energy_uj",
                 O_RDONLY, 0);
  if (IS_ERR(fp))
    return 0;

  ret = kernel_read(fp, buf, sizeof(buf) - 1, &pos);
  if (ret > 0) {
    buf[ret] = '\0';
    ret = kstrtou64(buf, 10, &energy);
    if (ret < 0)
      energy = 0;
  }

  filp_close(fp, NULL);
  return energy;
}

static void deepcool_calc_cpu_power(struct deepcool_device *ddata) {
  u64 current_energy;
  u64 delta_energy;
  unsigned long current_jiffies;
  unsigned long delta_ms;
  u64 max_energy_uj = 262143328850ULL; // default max for Intel RAPL

  current_energy = deepcool_read_cpu_energy();
  current_jiffies = jiffies;

  if (ddata->prev_energy_uj == 0 || current_energy == 0) {
    ddata->prev_energy_uj = current_energy;
    ddata->prev_jiffies = current_jiffies;
    ddata->cpu_power = 0;
    return;
  }

  delta_ms = jiffies_to_msecs(current_jiffies - ddata->prev_jiffies);
  if (delta_ms == 0) {
    ddata->cpu_power = 0;
    return;
  }

  // Handle counter rollover
  if (current_energy > ddata->prev_energy_uj)
    delta_energy = current_energy - ddata->prev_energy_uj;
  else
    delta_energy = (max_energy_uj + current_energy) - ddata->prev_energy_uj;

  // Calculate power: W = ΔμJ / (Δms * 1000)
  ddata->cpu_power = (u16)(delta_energy / (delta_ms * 1000));

  ddata->prev_energy_uj = current_energy;
  ddata->prev_jiffies = current_jiffies;
}

static void deepcool_update_sensors(struct deepcool_device *ddata) {
  ddata->cpu_temp = deepcool_read_cpu_temp();
  deepcool_read_cpu_usage(ddata);
  ddata->cpu_freq = deepcool_read_cpu_freq();
  deepcool_calc_cpu_power(ddata);
}

// Auto Mode Management
static enum deepcool_mode
deepcool_next_auto_mode(struct deepcool_device *ddata) {
  enum deepcool_mode next;

  switch (ddata->series) {
  case DEEPCOOL_AK_SERIES:
    // Cycle: cpu_temp -> cpu_usage -> cpu_temp
    if (ddata->auto_mode_current == MODE_CPU_TEMP)
      next = MODE_CPU_USAGE;
    else
      next = MODE_CPU_TEMP;
    break;

  case DEEPCOOL_LS_SERIES:
    // cpu_temp -> cpu_power -> cpu_temp
    if (ddata->auto_mode_current == MODE_CPU_TEMP)
      next = MODE_CPU_POWER;
    else
      next = MODE_CPU_TEMP;
    break;

  case DEEPCOOL_AG_SERIES:
    // cpu_temp -> cpu_usage -> cpu_temp
    if (ddata->auto_mode_current == MODE_CPU_TEMP)
      next = MODE_CPU_USAGE;
    else
      next = MODE_CPU_TEMP;
    break;

  case DEEPCOOL_AK620_PRO:
  case DEEPCOOL_AK400_PRO:
    // Always show all metrics simultaneously
    next = MODE_AUTO;
    break;

  default:
    next = MODE_CPU_TEMP;
    break;
  }

  return next;
}

static void deepcool_handle_auto_mode(struct deepcool_device *ddata) {
  unsigned long now = jiffies;

  if (time_after(now, ddata->auto_mode_last_change +
                          msecs_to_jiffies(AUTO_MODE_INTERVAL_MS))) {
    ddata->auto_mode_current = deepcool_next_auto_mode(ddata);
    ddata->auto_mode_last_change = now;
  }
}

// Device communication

static int deepcool_send_ak620_pro_packet(struct deepcool_device *ddata) {
  u8 *data = kzalloc(64, GFP_KERNEL);
  u16 checksum = 0;
  u16 power, freq;
  u8 temp;
  int i, ret;
  if (!data)
    return -ENOMEM;

  // Packet header
  data[0] = 16;
  data[1] = 104;
  data[2] = 1;
  data[3] = 4;
  data[4] = 13;
  data[5] = 1;
  data[6] = 2;
  data[7] = 8;

  // Power consumption (big-endian)
  power = cpu_to_be16(ddata->cpu_power);
  data[8] = (power >> 8) & 0xFF;
  data[9] = power & 0xFF;

  // Temp
  temp = ddata->cpu_temp;
  if (ddata->fahrenheit) {
    temp = (temp * 9 / 5) + 32;
    data[10] = 1;
  } else {
    data[10] = 0;
  }

  // Convert to float representation
  // TODO: this can be made more robust
  data[11] = 0;
  data[12] = 0;
  data[13] = temp;
  data[14] = 0;

  // Utilization
  data[15] = ddata->cpu_usage;

  // Frequency (big-endian)
  freq = cpu_to_be16(ddata->cpu_freq);
  data[16] = (freq >> 8) & 0xFF;
  data[17] = freq & 0xFF;

  // Calculate checksum
  for (i = 1; i <= 17; i++)
    checksum += data[i];
  data[18] = checksum % 256;
  data[19] = 22;

  // Send HID output report
  ret = hid_hw_output_report(ddata->hdev, data, 64);
  kfree(data);
  if (ret < 0) {
    hid_err(ddata->hdev, "Failed to send packet: %d\n", ret);
    return ret;
  }

  return 0;
}

static int deepcool_send_ak_series_packet(struct deepcool_device *ddata) {
  u8 *data = kzalloc(64, GFP_KERNEL);
  u16 checksum = 0;
  enum deepcool_mode current_mode;
  u8 mode_byte;
  int i, ret;
  if (!data)
    return -ENOMEM;

  // Determine current mode
  if (ddata->mode == MODE_AUTO) {
    deepcool_handle_auto_mode(ddata);
    current_mode = ddata->auto_mode_current;
  } else {
    current_mode = ddata->mode;
  }

  // Initialize packet header
  data[0] = 16;
  data[1] = 106;
  data[2] = 1;
  data[3] = 3;

  // Mode byte
  switch (current_mode) {
  case MODE_CPU_TEMP:
    mode_byte = 0;
    break;
  case MODE_CPU_USAGE:
    mode_byte = 1;
    break;
  default:
    mode_byte = 0;
    break;
  }
  data[4] = mode_byte;

  // Alarm flag
  data[5] = ddata->alarm_enabled ? 1 : 0;

  // Temperature/usage value
  if (current_mode == MODE_CPU_TEMP) {
    u8 temp = ddata->cpu_temp;
    if (ddata->fahrenheit)
      temp = (temp * 9 / 5) + 32;
    data[6] = temp;
  } else {
    data[6] = ddata->cpu_usage;
  }

  // Calculate checksum
  for (i = 1; i <= 6; i++)
    checksum += data[i];
  data[7] = checksum % 256;
  data[8] = 22;

  // Send HID output report
  ret = hid_hw_output_report(ddata->hdev, data, 64);
  kfree(data);
  if (ret < 0) {
    hid_err(ddata->hdev, "Failed to send packet: %d\n", ret);
    return ret;
  }

  return 0;
}

static int deepcool_send_ls_series_packet(struct deepcool_device *ddata) {
  u8 *data = kzalloc(64, GFP_KERNEL);
  u16 checksum = 0;
  enum deepcool_mode current_mode;
  u8 mode_byte;
  u16 value;
  int i, ret;
  if (!data)
    return -ENOMEM;

  // Determine current mode
  if (ddata->mode == MODE_AUTO) {
    deepcool_handle_auto_mode(ddata);
    current_mode = ddata->auto_mode_current;
  } else {
    current_mode = ddata->mode;
  }

  // Initialize packet header
  data[0] = 16;
  data[1] = 175;
  data[2] = 3;

  // Mode byte
  switch (current_mode) {
  case MODE_CPU_TEMP:
    mode_byte = 0;
    break;
  case MODE_CPU_POWER:
    mode_byte = 2;
    break;
  default:
    mode_byte = 0;
    break;
  }
  data[3] = mode_byte;

  // Alarm flag
  data[4] = ddata->alarm_enabled ? 1 : 0;

  // Value (big-endian)
  if (current_mode == MODE_CPU_TEMP) {
    u8 temp = ddata->cpu_temp;
    if (ddata->fahrenheit)
      temp = (temp * 9 / 5) + 32;
    value = cpu_to_be16(temp);
  } else {
    value = cpu_to_be16(ddata->cpu_power);
  }
  data[5] = (value >> 8) & 0xFF;
  data[6] = value & 0xFF;

  // Calculate checksum
  for (i = 1; i <= 6; i++)
    checksum += data[i];
  data[7] = checksum % 256;
  data[8] = 22;

  // Send HID output report
  ret = hid_hw_output_report(ddata->hdev, data, 64);
  kfree(data);
  if (ret < 0) {
    hid_err(ddata->hdev, "Failed to send packet: %d\n", ret);
    return ret;
  }

  return 0;
}

static int deepcool_send_ag_series_packet(struct deepcool_device *ddata) {
  u8 *data = kzalloc(64, GFP_KERNEL);
  u16 checksum = 0;
  enum deepcool_mode current_mode;
  u8 mode_byte;
  int i, ret;
  if (!data)
    return -ENOMEM;

  // Determine current mode
  if (ddata->mode == MODE_AUTO) {
    deepcool_handle_auto_mode(ddata);
    current_mode = ddata->auto_mode_current;
  } else {
    current_mode = ddata->mode;
  }

  // Initialize packet header
  data[0] = 16;
  data[1] = 170;
  data[2] = 1;
  data[3] = 3;

  // Mode byte
  switch (current_mode) {
  case MODE_CPU_TEMP:
    mode_byte = 0;
    break;
  case MODE_CPU_USAGE:
    mode_byte = 1;
    break;
  default:
    mode_byte = 0;
    break;
  }
  data[4] = mode_byte;

  // Alarm flag
  data[5] = ddata->alarm_enabled ? 1 : 0;

  // Temperature/usage value
  if (current_mode == MODE_CPU_TEMP) {
    data[6] = ddata->cpu_temp;
  } else {
    data[6] = ddata->cpu_usage;
  }

  // Calculate checksum
  for (i = 1; i <= 6; i++)
    checksum += data[i];
  data[7] = checksum % 256;
  data[8] = 22; // termination byte

  // Send HID output report
  ret = hid_hw_output_report(ddata->hdev, data, 64);
  kfree(data);
  if (ret < 0) {
    hid_err(ddata->hdev, "Failed to send packet: %d\n", ret);
    return ret;
  }

  return 0;
}

static int deepcool_send_packet(struct deepcool_device *ddata) {
  int ret;

  switch (ddata->series) {
  case DEEPCOOL_AK620_PRO:
  case DEEPCOOL_AK400_PRO:
    ret = deepcool_send_ak620_pro_packet(ddata);
    break;
  case DEEPCOOL_AK_SERIES:
    ret = deepcool_send_ak_series_packet(ddata);
    break;
  case DEEPCOOL_LS_SERIES:
    ret = deepcool_send_ls_series_packet(ddata);
    break;
  case DEEPCOOL_AG_SERIES:
    ret = deepcool_send_ag_series_packet(ddata);
    break;
  default:
    hid_warn(ddata->hdev, "Unsupported device series\n");
    ret = -EOPNOTSUPP;
    break;
  }

  return ret;
}

// Work queue handler
static void deepcool_update_work(struct work_struct *work) {
  struct deepcool_device *ddata =
      container_of(work, struct deepcool_device, update_work.work);

  mutex_lock(&ddata->lock);

  // Update sensor readings
  deepcool_update_sensors(ddata);

  // Send updated packet to device
  deepcool_send_packet(ddata);

  mutex_unlock(&ddata->lock);

  // Schedule next update
  schedule_delayed_work(&ddata->update_work,
                        msecs_to_jiffies(ddata->update_interval_ms));
}

// Sysfs attrs

static ssize_t mode_show(struct device *dev, struct device_attribute *attr,
                         char *buf) {
  struct deepcool_device *ddata = dev_get_drvdata(dev);
  const char *mode_str;

  mutex_lock(&ddata->lock);
  mode_str = mode_names[ddata->mode];
  mutex_unlock(&ddata->lock);

  return sprintf(buf, "%s\n", mode_str);
}

static ssize_t mode_store(struct device *dev, struct device_attribute *attr,
                          const char *buf, size_t count) {
  struct deepcool_device *ddata = dev_get_drvdata(dev);
  char mode_str[32];
  enum deepcool_mode new_mode = MODE_DEFAULT;
  int i;

  if (count >= sizeof(mode_str))
    return -EINVAL;

  memcpy(mode_str, buf, count);
  mode_str[count] = '\0';

  if (mode_str[count - 1] == '\n')
    mode_str[count - 1] = '\0';

  // Find matching mode
  for (i = 0; i < MODE_MAX; i++) {
    if (mode_names[i] && strcmp(mode_str, mode_names[i]) == 0) {
      new_mode = i;
      break;
    }
  }

  if (i == MODE_MAX)
    return -EINVAL;

  mutex_lock(&ddata->lock);
  ddata->mode = new_mode;
  if (new_mode == MODE_AUTO) {
    ddata->auto_mode_current = MODE_CPU_TEMP;
    ddata->auto_mode_last_change = jiffies;
  }
  mutex_unlock(&ddata->lock);

  return count;
}

static ssize_t update_interval_show(struct device *dev,
                                    struct device_attribute *attr, char *buf) {
  struct deepcool_device *ddata = dev_get_drvdata(dev);
  unsigned int interval;

  mutex_lock(&ddata->lock);
  interval = ddata->update_interval_ms;
  mutex_unlock(&ddata->lock);

  return sprintf(buf, "%u\n", interval);
}

static ssize_t update_interval_store(struct device *dev,
                                     struct device_attribute *attr,
                                     const char *buf, size_t count) {
  struct deepcool_device *ddata = dev_get_drvdata(dev);
  unsigned int interval;
  int ret;

  ret = kstrtouint(buf, 10, &interval);
  if (ret)
    return ret;

  if (interval < MIN_UPDATE_INTERVAL_MS || interval > MAX_UPDATE_INTERVAL_MS)
    return -EINVAL;

  mutex_lock(&ddata->lock);
  ddata->update_interval_ms = interval;
  mutex_unlock(&ddata->lock);

  // Restart work with new interval
  cancel_delayed_work_sync(&ddata->update_work);
  schedule_delayed_work(&ddata->update_work, msecs_to_jiffies(interval));

  return count;
}

static ssize_t fahrenheit_show(struct device *dev,
                               struct device_attribute *attr, char *buf) {
  struct deepcool_device *ddata = dev_get_drvdata(dev);
  bool fahrenheit;

  mutex_lock(&ddata->lock);
  fahrenheit = ddata->fahrenheit;
  mutex_unlock(&ddata->lock);

  return sprintf(buf, "%d\n", fahrenheit ? 1 : 0);
}

static ssize_t fahrenheit_store(struct device *dev,
                                struct device_attribute *attr, const char *buf,
                                size_t count) {
  struct deepcool_device *ddata = dev_get_drvdata(dev);
  bool value;
  int ret;

  ret = kstrtobool(buf, &value);
  if (ret)
    return ret;

  if (value && !ddata->supports_fahrenheit)
    return -EOPNOTSUPP;

  mutex_lock(&ddata->lock);
  ddata->fahrenheit = value;
  mutex_unlock(&ddata->lock);

  return count;
}

static ssize_t alarm_show(struct device *dev, struct device_attribute *attr,
                          char *buf) {
  struct deepcool_device *ddata = dev_get_drvdata(dev);
  bool alarm;

  mutex_lock(&ddata->lock);
  alarm = ddata->alarm_enabled;
  mutex_unlock(&ddata->lock);

  return sprintf(buf, "%d\n", alarm ? 1 : 0);
}

static ssize_t alarm_store(struct device *dev, struct device_attribute *attr,
                           const char *buf, size_t count) {
  struct deepcool_device *ddata = dev_get_drvdata(dev);
  bool value;
  int ret;

  ret = kstrtobool(buf, &value);
  if (ret)
    return ret;

  if (value && !ddata->supports_alarm)
    return -EOPNOTSUPP;

  mutex_lock(&ddata->lock);
  ddata->alarm_enabled = value;
  mutex_unlock(&ddata->lock);

  return count;
}

static ssize_t cpu_temp_show(struct device *dev, struct device_attribute *attr,
                             char *buf) {
  struct deepcool_device *ddata = dev_get_drvdata(dev);
  s32 temp;

  mutex_lock(&ddata->lock);
  temp = ddata->cpu_temp;
  if (ddata->fahrenheit)
    temp = (temp * 9 / 5) + 32;
  mutex_unlock(&ddata->lock);

  return sprintf(buf, "%d\n", temp);
}

static ssize_t cpu_usage_show(struct device *dev, struct device_attribute *attr,
                              char *buf) {
  struct deepcool_device *ddata = dev_get_drvdata(dev);
  u8 usage;

  mutex_lock(&ddata->lock);
  usage = ddata->cpu_usage;
  mutex_unlock(&ddata->lock);

  return sprintf(buf, "%u\n", usage);
}

static ssize_t cpu_power_show(struct device *dev, struct device_attribute *attr,
                              char *buf) {
  struct deepcool_device *ddata = dev_get_drvdata(dev);
  u16 power;

  mutex_lock(&ddata->lock);
  power = ddata->cpu_power;
  mutex_unlock(&ddata->lock);

  return sprintf(buf, "%u\n", power);
}

static ssize_t cpu_freq_show(struct device *dev, struct device_attribute *attr,
                             char *buf) {
  struct deepcool_device *ddata = dev_get_drvdata(dev);
  u16 freq;

  mutex_lock(&ddata->lock);
  freq = ddata->cpu_freq;
  mutex_unlock(&ddata->lock);

  return sprintf(buf, "%u\n", freq);
}

static DEVICE_ATTR_RW(mode);
static DEVICE_ATTR_RW(update_interval);
static DEVICE_ATTR_RW(fahrenheit);
static DEVICE_ATTR_RW(alarm);
static DEVICE_ATTR_RO(cpu_temp);
static DEVICE_ATTR_RO(cpu_usage);
static DEVICE_ATTR_RO(cpu_power);
static DEVICE_ATTR_RO(cpu_freq);

static struct attribute *deepcool_attrs[] = {&dev_attr_mode.attr,
                                             &dev_attr_update_interval.attr,
                                             &dev_attr_fahrenheit.attr,
                                             &dev_attr_alarm.attr,
                                             &dev_attr_cpu_temp.attr,
                                             &dev_attr_cpu_usage.attr,
                                             &dev_attr_cpu_power.attr,
                                             &dev_attr_cpu_freq.attr,
                                             NULL};

ATTRIBUTE_GROUPS(deepcool);

// Device identification

static enum deepcool_series deepcool_identify_device(u16 product_id) {
  switch (product_id) {
  case 1 ... 4:
    return DEEPCOOL_AK_SERIES;
  case 5:
    return DEEPCOOL_AK400_PRO;
  case 6:
    return DEEPCOOL_LS_SERIES;
  case 7:
    return DEEPCOOL_AK620_PRO;
  case 8:
    return DEEPCOOL_AG_SERIES;
  case 9:
    return DEEPCOOL_LQ_SERIES;
  case 10 ... 11:
    return DEEPCOOL_LD_SERIES;
  case 12 ... 14:
    return DEEPCOOL_LP_SERIES;
  case 15 ... 17:
    return DEEPCOOL_CH_SERIES;
  case 18 ... 21:
    return DEEPCOOL_CH_SERIES_GEN2;
  case CH510_PRODUCT_ID:
    return DEEPCOOL_CH510;
  default:
    return DEEPCOOL_UNKNOWN;
  }
}

static void deepcool_set_capabilities(struct deepcool_device *ddata) {
  // Set default capabilities based on device series
  switch (ddata->series) {
  case DEEPCOOL_AK_SERIES:
    ddata->supports_alarm = true;
    ddata->supports_fahrenheit = true;
    ddata->supports_secondary_mode = false;
    ddata->supports_rotation = false;
    break;

  case DEEPCOOL_LS_SERIES:
    ddata->supports_alarm = true;
    ddata->supports_fahrenheit = true;
    ddata->supports_secondary_mode = false;
    ddata->supports_rotation = false;
    break;

  case DEEPCOOL_AG_SERIES:
    ddata->supports_alarm = true;
    ddata->supports_fahrenheit = false;
    ddata->supports_secondary_mode = false;
    ddata->supports_rotation = false;
    break;

  case DEEPCOOL_LP_SERIES:
    ddata->supports_alarm = false;
    ddata->supports_fahrenheit = true;
    ddata->supports_secondary_mode = true;
    ddata->supports_rotation = true;
    break;

  case DEEPCOOL_AK620_PRO:
  case DEEPCOOL_AK400_PRO:
    ddata->supports_alarm = false; // hard-coded alarm
    ddata->supports_fahrenheit = true;
    ddata->supports_secondary_mode = false;
    ddata->supports_rotation = false;
    break;

  default:
    ddata->supports_alarm = false;
    ddata->supports_fahrenheit = false;
    ddata->supports_secondary_mode = false;
    ddata->supports_rotation = false;
    break;
  }
}

// HID Driver Callbacks
static int deepcool_probe(struct hid_device *hdev,
                          const struct hid_device_id *id) {
  struct deepcool_device *ddata;
  int ret;

  ddata = devm_kzalloc(&hdev->dev, sizeof(*ddata), GFP_KERNEL);
  if (!ddata)
    return -ENOMEM;

  ddata->hdev = hdev;
  ddata->product_id = hdev->product;
  ddata->series = deepcool_identify_device(hdev->product);

  if (ddata->series == DEEPCOOL_UNKNOWN) {
    hid_err(hdev, "Unknown Deepcool device: 0x%04x\n", hdev->product);
    return -ENODEV;
  }

  // Set device capabilities
  deepcool_set_capabilities(ddata);

  // Initialize default configuration
  ddata->mode = MODE_AUTO;
  ddata->auto_mode_current = MODE_CPU_TEMP;
  ddata->auto_mode_last_change = jiffies;
  ddata->secondary_mode = MODE_DEFAULT;
  ddata->update_interval_ms = DEFAULT_UPDATE_INTERVAL_MS;
  ddata->fahrenheit = false;
  ddata->alarm_enabled = false;
  ddata->rotation = 0;

  mutex_init(&ddata->lock);
  hid_set_drvdata(hdev, ddata);

  ret = hid_parse(hdev);
  if (ret) {
    hid_err(hdev, "HID parse failed: %d\n", ret);
    return ret;
  }

  ret = hid_hw_start(hdev, HID_CONNECT_HIDRAW);
  if (ret) {
    hid_err(hdev, "HID hw start failed: %d\n", ret);
    return ret;
  }

  ret = hid_hw_open(hdev);
  if (ret) {
    hid_err(hdev, "HID hw open failed: %d\n", ret);
    goto err_hw_stop;
  }

  // Create sysfs attributes
  ret = sysfs_create_group(&hdev->dev.kobj, &deepcool_group);
  if (ret) {
    hid_err(hdev, "Failed to create sysfs group: %d\n", ret);
    goto err_hw_close;
  }

  // Initialize work queue
  INIT_DELAYED_WORK(&ddata->update_work, deepcool_update_work);

  // Start update work
  schedule_delayed_work(&ddata->update_work,
                        msecs_to_jiffies(ddata->update_interval_ms));

  hid_info(hdev, "Deepcool Digital device initialized (series: %d)\n",
           ddata->series);

  return 0;

err_hw_close:
  hid_hw_close(hdev);
err_hw_stop:
  hid_hw_stop(hdev);
  return ret;
}

static void deepcool_remove(struct hid_device *hdev) {
  struct deepcool_device *ddata = hid_get_drvdata(hdev);

  // Stop work queue
  cancel_delayed_work_sync(&ddata->update_work);

  // Remove sysfs attributes
  sysfs_remove_group(&hdev->dev.kobj, &deepcool_group);

  hid_hw_close(hdev);
  hid_hw_stop(hdev);

  hid_info(hdev, "Deepcool Digital device removed\n");
}

// HID Device ID Table
static const struct hid_device_id deepcool_devices[] = {
    /* Deepcool Digital devices (vendor ID 0x3633) */
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 1)}, // AK Series
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 2)},
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 3)},
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 4)},
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 5)},  // AK400 PRO
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 6)},  // LS Series
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 7)},  // AK620 PRO
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 8)},  // AG Series
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 9)},  // LQ Series
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 10)}, // LD Series
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 11)},
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 12)}, // LP Series
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 13)},
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 14)},
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 15)}, // CH Series
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 16)},
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 17)},
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 18)}, // CH Series Gen2
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 19)},
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 20)},
    {HID_USB_DEVICE(DEEPCOOL_VENDOR_ID, 21)},
    {HID_USB_DEVICE(CH510_VENDOR_ID,
                    CH510_PRODUCT_ID)}, // CH510 (different vendor ID)
    {}};
MODULE_DEVICE_TABLE(hid, deepcool_devices);

// Represents a HID device
static struct hid_driver deepcool_driver = {
    .name = DRIVER_NAME,
    .id_table = deepcool_devices,
    .probe = deepcool_probe,
    .remove = deepcool_remove,
    .driver =
        {
            .groups = deepcool_groups,
        },
};
module_hid_driver(deepcool_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("NotAShelf <raf@notashelf.dev>");
MODULE_DESCRIPTION("Deepcool Digital USB HID driver");
MODULE_VERSION(DRIVER_VERSION);