// SPDX-License-Identifier: GPL-2.0-or-later

  /*

   * atxp1.c - kernel module for setting CPU VID and general purpose
   *	     I/Os using the Attansic ATXP1 chip.
   *

   * The ATXP1 can reside on I2C addresses 0x37 or 0x4e. The chip is
   * not auto-detected by the driver and must be instantiated explicitly.

   * See Documentation/i2c/instantiating-devices.rst for more information.

   */

  
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/module.h>

  #include <linux/jiffies.h>

  #include <linux/i2c.h>

  #include <linux/hwmon.h>

  #include <linux/hwmon-vid.h>

  #include <linux/err.h>

  #include <linux/mutex.h>

  #include <linux/sysfs.h>

  #include <linux/slab.h>

  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("System voltages control via Attansic ATXP1");

  MODULE_VERSION("0.6.3");

  MODULE_AUTHOR("Sebastian Witt <se.witt@gmx.net>");
  
  #define ATXP1_VID	0x00
  #define ATXP1_CVID	0x01
  #define ATXP1_GPIO1	0x06
  #define ATXP1_GPIO2	0x0a
  #define ATXP1_VIDENA	0x20
  #define ATXP1_VIDMASK	0x1f
  #define ATXP1_GPIO1MASK	0x0f

  struct atxp1_data {

  	struct i2c_client *client;

  	struct mutex update_lock;

  	unsigned long last_updated;
  	u8 valid;
  	struct {
  		u8 vid;		/* VID output register */
  		u8 cpu_vid; /* VID input from CPU */
  		u8 gpio1;   /* General purpose I/O register 1 */
  		u8 gpio2;   /* General purpose I/O register 2 */
  	} reg;
  	u8 vrm;			/* Detected CPU VRM */
  };

  static struct atxp1_data *atxp1_update_device(struct device *dev)

  {

  	struct atxp1_data *data = dev_get_drvdata(dev);
  	struct i2c_client *client = data->client;

  	mutex_lock(&data->update_lock);

  	if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {

  
  		/* Update local register data */
  		data->reg.vid = i2c_smbus_read_byte_data(client, ATXP1_VID);

  		data->reg.cpu_vid = i2c_smbus_read_byte_data(client,
  							     ATXP1_CVID);

  		data->reg.gpio1 = i2c_smbus_read_byte_data(client, ATXP1_GPIO1);
  		data->reg.gpio2 = i2c_smbus_read_byte_data(client, ATXP1_GPIO2);
  
  		data->valid = 1;
  	}

  	mutex_unlock(&data->update_lock);

  	return data;

  }
  
  /* sys file functions for cpu0_vid */

  static ssize_t cpu0_vid_show(struct device *dev,
  			     struct device_attribute *attr, char *buf)

  {
  	int size;
  	struct atxp1_data *data;
  
  	data = atxp1_update_device(dev);

  	size = sprintf(buf, "%d
  ", vid_from_reg(data->reg.vid & ATXP1_VIDMASK,
  						 data->vrm));

  
  	return size;
  }

  static ssize_t cpu0_vid_store(struct device *dev,
  			      struct device_attribute *attr, const char *buf,
  			      size_t count)

  {

  	struct atxp1_data *data = atxp1_update_device(dev);
  	struct i2c_client *client = data->client;

  	int vid, cvid;

  	unsigned long vcore;
  	int err;

  	err = kstrtoul(buf, 10, &vcore);
  	if (err)
  		return err;

  	vcore /= 25;
  	vcore *= 25;
  
  	/* Calculate VID */
  	vid = vid_to_reg(vcore, data->vrm);

  	if (vid < 0) {
  		dev_err(dev, "VID calculation failed.
  ");

  		return vid;

  	}

  	/*
  	 * If output enabled, use control register value.
  	 * Otherwise original CPU VID
  	 */

  	if (data->reg.vid & ATXP1_VIDENA)
  		cvid = data->reg.vid & ATXP1_VIDMASK;
  	else
  		cvid = data->reg.cpu_vid;
  
  	/* Nothing changed, aborting */
  	if (vid == cvid)
  		return count;

  	dev_dbg(dev, "Setting VCore to %d mV (0x%02x)
  ", (int)vcore, vid);

  
  	/* Write every 25 mV step to increase stability */
  	if (cvid > vid) {

  		for (; cvid >= vid; cvid--)
  			i2c_smbus_write_byte_data(client,
  						ATXP1_VID, cvid | ATXP1_VIDENA);
  	} else {
  		for (; cvid <= vid; cvid++)
  			i2c_smbus_write_byte_data(client,
  						ATXP1_VID, cvid | ATXP1_VIDENA);

  	}
  
  	data->valid = 0;
  
  	return count;
  }

  /*
   * CPU core reference voltage
   * unit: millivolt
   */

  static DEVICE_ATTR_RW(cpu0_vid);

  
  /* sys file functions for GPIO1 */

  static ssize_t gpio1_show(struct device *dev, struct device_attribute *attr,
  			  char *buf)

  {
  	int size;
  	struct atxp1_data *data;
  
  	data = atxp1_update_device(dev);
  
  	size = sprintf(buf, "0x%02x
  ", data->reg.gpio1 & ATXP1_GPIO1MASK);
  
  	return size;
  }

  static ssize_t gpio1_store(struct device *dev, struct device_attribute *attr,
  			   const char *buf, size_t count)

  {

  	struct atxp1_data *data = atxp1_update_device(dev);
  	struct i2c_client *client = data->client;

  	unsigned long value;
  	int err;

  	err = kstrtoul(buf, 16, &value);
  	if (err)
  		return err;

  
  	value &= ATXP1_GPIO1MASK;
  
  	if (value != (data->reg.gpio1 & ATXP1_GPIO1MASK)) {

  		dev_info(dev, "Writing 0x%x to GPIO1.
  ", (unsigned int)value);

  
  		i2c_smbus_write_byte_data(client, ATXP1_GPIO1, value);
  
  		data->valid = 0;
  	}
  
  	return count;
  }

  /*
   * GPIO1 data register
   * unit: Four bit as hex (e.g. 0x0f)
   */

  static DEVICE_ATTR_RW(gpio1);

  
  /* sys file functions for GPIO2 */

  static ssize_t gpio2_show(struct device *dev, struct device_attribute *attr,
  			  char *buf)

  {
  	int size;
  	struct atxp1_data *data;
  
  	data = atxp1_update_device(dev);
  
  	size = sprintf(buf, "0x%02x
  ", data->reg.gpio2);
  
  	return size;
  }

  static ssize_t gpio2_store(struct device *dev, struct device_attribute *attr,
  			   const char *buf, size_t count)

  {

  	struct atxp1_data *data = atxp1_update_device(dev);

  	struct i2c_client *client = data->client;

  	unsigned long value;
  	int err;

  	err = kstrtoul(buf, 16, &value);
  	if (err)
  		return err;
  	value &= 0xff;

  
  	if (value != data->reg.gpio2) {

  		dev_info(dev, "Writing 0x%x to GPIO1.
  ", (unsigned int)value);

  
  		i2c_smbus_write_byte_data(client, ATXP1_GPIO2, value);
  
  		data->valid = 0;
  	}
  
  	return count;
  }

  /*
   * GPIO2 data register
   * unit: Eight bit as hex (e.g. 0xff)
   */

  static DEVICE_ATTR_RW(gpio2);

  static struct attribute *atxp1_attrs[] = {

  	&dev_attr_gpio1.attr,
  	&dev_attr_gpio2.attr,
  	&dev_attr_cpu0_vid.attr,
  	NULL
  };

  ATTRIBUTE_GROUPS(atxp1);

  static int atxp1_probe(struct i2c_client *client)

  {

  	struct device *dev = &client->dev;

  	struct atxp1_data *data;

  	struct device *hwmon_dev;

  	data = devm_kzalloc(dev, sizeof(struct atxp1_data), GFP_KERNEL);

  	if (!data)
  		return -ENOMEM;

  	/* Get VRM */
  	data->vrm = vid_which_vrm();

  	if (data->vrm != 90 && data->vrm != 91) {
  		dev_err(dev, "atxp1: Not supporting VRM %d.%d
  ",
  			data->vrm / 10, data->vrm % 10);
  		return -ENODEV;
  	}

  	data->client = client;

  	mutex_init(&data->update_lock);

  	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
  							   data,
  							   atxp1_groups);
  	if (IS_ERR(hwmon_dev))
  		return PTR_ERR(hwmon_dev);

  	dev_info(dev, "Using VRM: %d.%d
  ", data->vrm / 10, data->vrm % 10);

  	return 0;

  };

  static const struct i2c_device_id atxp1_id[] = {
  	{ "atxp1", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, atxp1_id);
  
  static struct i2c_driver atxp1_driver = {
  	.class		= I2C_CLASS_HWMON,
  	.driver = {
  		.name	= "atxp1",
  	},

  	.probe_new	= atxp1_probe,

  	.id_table	= atxp1_id,

  };

  module_i2c_driver(atxp1_driver);