text: // SPDX-License-Identifier: GPL-2.0-or-later
  /*
   * Copyright (C) 2001-2004 Aurelien Jarno <aurelien@aurel32.net>
   * Ported to Linux 2.6 by Aurelien Jarno <aurelien@aurel32.net> with
   * the help of Jean Delvare <jdelvare@suse.de>
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/slab.h>
  #include <linux/i2c.h>
  #include <linux/mutex.h>
  #include <linux/err.h>
  #include <linux/hwmon.h>
  
  /* Insmod parameters */
  
  static int input_mode;
  module_param(input_mode, int, 0);
  MODULE_PARM_DESC(input_mode,
  	"Analog input mode:\n"
  	" 0 = four single ended inputs\n"
  	" 1 = three differential inputs\n"
  	" 2 = single ended and differential mixed\n"
  	" 3 = two differential inputs\n");
  
  /*
   * The PCF8591 control byte
   *      7    6    5    4    3    2    1    0
   *   |  0 |AOEF|   AIP   |  0 |AINC|  AICH   |
   */
  
  /* Analog Output Enable Flag (analog output active if 1) */
  #define PCF8591_CONTROL_AOEF		0x40
  
  /*
   * Analog Input Programming
   * 0x00 = four single ended inputs
   * 0x10 = three differential inputs
   * 0x20 = single ended and differential mixed
   * 0x30 = two differential inputs
   */
  #define PCF8591_CONTROL_AIP_MASK	0x30
  
  /* Autoincrement Flag (switch on if 1) */
  #define PCF8591_CONTROL_AINC		0x04
  
  /*
   * Channel selection
   * 0x00 = channel 0
   * 0x01 = channel 1
   * 0x02 = channel 2
   * 0x03 = channel 3
   */
  #define PCF8591_CONTROL_AICH_MASK	0x03
  
  /* Initial values */
  #define PCF8591_INIT_CONTROL	((input_mode << 4) | PCF8591_CONTROL_AOEF)
  #define PCF8591_INIT_AOUT	0	/* DAC out = 0 */
  
  /* Conversions */
  #define REG_TO_SIGNED(reg)	(((reg) & 0x80) ? ((reg) - 256) : (reg))
  
  struct pcf8591_data {
  	struct device *hwmon_dev;
  	struct mutex update_lock;
  
  	u8 control;
  	u8 aout;
  };
  
  static void pcf8591_init_client(struct i2c_client *client);
  static int pcf8591_read_channel(struct device *dev, int channel);
  
  /* following are the sysfs callback functions */
  #define show_in_channel(channel)					\
  static ssize_t show_in##channel##_input(struct device *dev,		\
  					struct device_attribute *attr,	\
  					char *buf)			\
  {									\
  	return sprintf(buf, "%d\n", pcf8591_read_channel(dev, channel));\
  }									\
  static DEVICE_ATTR(in##channel##_input, S_IRUGO,			\
  		   show_in##channel##_input, NULL);
  
  show_in_channel(0);
  show_in_channel(1);
  show_in_channel(2);
  show_in_channel(3);
  
  static ssize_t out0_output_show(struct device *dev,
  				struct device_attribute *attr, char *buf)
  {
  	struct pcf8591_data *data = i2c_get_clientdata(to_i2c_client(dev));
  	return sprintf(buf, "%d\n", data->aout * 10);
  }
  
  static ssize_t out0_output_store(struct device *dev,
  				 struct device_attribute *attr,
  				 const char *buf, size_t count)
  {
  	unsigned long val;
  	struct i2c_client *client = to_i2c_client(dev);
  	struct pcf8591_data *data = i2c_get_clientdata(client);
  	int err;
  
  	err = kstrtoul(buf, 10, &val);
  	if (err)
  		return err;
  
  	val /= 10;
  	if (val > 255)
  		return -EINVAL;
  
  	data->aout = val;
  	i2c_smbus_write_byte_data(client, data->control, data->aout);
  	return count;
  }
  
  static DEVICE_ATTR_RW(out0_output);
  
  static ssize_t out0_enable_show(struct device *dev,
  				struct device_attribute *attr, char *buf)
  {
  	struct pcf8591_data *data = i2c_get_clientdata(to_i2c_client(dev));
  	return sprintf(buf, "%u\n", !(!(data->control & PCF8591_CONTROL_AOEF)));
  }
  
  static ssize_t out0_enable_store(struct device *dev,
  				 struct device_attribute *attr,
  				 const char *buf, size_t count)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct pcf8591_data *data = i2c_get_clientdata(client);
  	unsigned long val;
  	int err;
  
  	err = kstrtoul(buf, 10, &val);
  	if (err)
  		return err;
  
  	mutex_lock(&data->update_lock);
  	if (val)
  		data->control |= PCF8591_CONTROL_AOEF;
  	else
  		data->control &= ~PCF8591_CONTROL_AOEF;
  	i2c_smbus_write_byte(client, data->control);
  	mutex_unlock(&data->update_lock);
  	return count;
  }
  
  static DEVICE_ATTR_RW(out0_enable);
  
  static struct attribute *pcf8591_attributes[] = {
  	&dev_attr_out0_enable.attr,
  	&dev_attr_out0_output.attr,
  	&dev_attr_in0_input.attr,
  	&dev_attr_in1_input.attr,
  	NULL
  };
  
  static const struct attribute_group pcf8591_attr_group = {
  	.attrs = pcf8591_attributes,
  };
  
  static struct attribute *pcf8591_attributes_opt[] = {
  	&dev_attr_in2_input.attr,
  	&dev_attr_in3_input.attr,
  	NULL
  };
  
  static const struct attribute_group pcf8591_attr_group_opt = {
  	.attrs = pcf8591_attributes_opt,
  };
  
  /*
   * Real code
   */
  
  static int pcf8591_probe(struct i2c_client *client,
  			 const struct i2c_device_id *id)
  {
  	struct pcf8591_data *data;
  	int err;
  
  	data = devm_kzalloc(&client->dev, sizeof(struct pcf8591_data),
  			    GFP_KERNEL);
  	if (!data)
  		return -ENOMEM;
  
  	i2c_set_clientdata(client, data);
  	mutex_init(&data->update_lock);
  
  	/* Initialize the PCF8591 chip */
  	pcf8591_init_client(client);
  
  	/* Register sysfs hooks */
  	err = sysfs_create_group(&client->dev.kobj, &pcf8591_attr_group);
  	if (err)
  		return err;
  
  	/* Register input2 if not in "two differential inputs" mode */
  	if (input_mode != 3) {
  		err = device_create_file(&client->dev, &dev_attr_in2_input);
  		if (err)
  			goto exit_sysfs_remove;
  	}
  
  	/* Register input3 only in "four single ended inputs" mode */
  	if (input_mode == 0) {
  		err = device_create_file(&client->dev, &dev_attr_in3_input);
  		if (err)
  			goto exit_sysfs_remove;
  	}
  
  	data->hwmon_dev = hwmon_device_register(&client->dev);
  	if (IS_ERR(data->hwmon_dev)) {
  		err = PTR_ERR(data->hwmon_dev);
  		goto exit_sysfs_remove;
  	}
  
  	return 0;
  
  exit_sysfs_remove:
  	sysfs_remove_group(&client->dev.kobj, &pcf8591_attr_group_opt);
  	sysfs_remove_group(&client->dev.kobj, &pcf8591_attr_group);
  	return err;
  }
  
  static int pcf8591_remove(struct i2c_client *client)
  {
  	struct pcf8591_data *data = i2c_get_clientdata(client);
  
  	hwmon_device_unregister(data->hwmon_dev);
  	sysfs_remove_group(&client->dev.kobj, &pcf8591_attr_group_opt);
  	sysfs_remove_group(&client->dev.kobj, &pcf8591_attr_group);
  	return 0;
  }
  
  /* Called when we have found a new PCF8591. */
  static void pcf8591_init_client(struct i2c_client *client)
  {
  	struct pcf8591_data *data = i2c_get_clientdata(client);
  	data->control = PCF8591_INIT_CONTROL;
  	data->aout = PCF8591_INIT_AOUT;
  
  	i2c_smbus_write_byte_data(client, data->control, data->aout);
  
  	/*
  	 * The first byte transmitted contains the conversion code of the
  	 * previous read cycle. FLUSH IT!
  	 */
  	i2c_smbus_read_byte(client);
  }
  
  static int pcf8591_read_channel(struct device *dev, int channel)
  {
  	u8 value;
  	struct i2c_client *client = to_i2c_client(dev);
  	struct pcf8591_data *data = i2c_get_clientdata(client);
  
  	mutex_lock(&data->update_lock);
  
  	if ((data->control & PCF8591_CONTROL_AICH_MASK) != channel) {
  		data->control = (data->control & ~PCF8591_CONTROL_AICH_MASK)
  			      | channel;
  		i2c_smbus_write_byte(client, data->control);
  
  		/*
  		 * The first byte transmitted contains the conversion code of
  		 * the previous read cycle. FLUSH IT!
  		 */
  		i2c_smbus_read_byte(client);
  	}
  	value = i2c_smbus_read_byte(client);
  
  	mutex_unlock(&data->update_lock);
  
  	if ((channel == 2 && input_mode == 2) ||
  	    (channel != 3 && (input_mode == 1 || input_mode == 3)))
  		return 10 * REG_TO_SIGNED(value);
  	else
  		return 10 * value;
  }
  
  static const struct i2c_device_id pcf8591_id[] = {
  	{ "pcf8591", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, pcf8591_id);
  
  static struct i2c_driver pcf8591_driver = {
  	.driver = {
  		.name	= "pcf8591",
  	},
  	.probe		= pcf8591_probe,
  	.remove		= pcf8591_remove,
  	.id_table	= pcf8591_id,
  };
  
  static int __init pcf8591_init(void)
  {
  	if (input_mode < 0 || input_mode > 3) {
  		pr_warn("invalid input_mode (%d)\n", input_mode);
  		input_mode = 0;
  	}
  	return i2c_add_driver(&pcf8591_driver);
  }
  
  static void __exit pcf8591_exit(void)
  {
  	i2c_del_driver(&pcf8591_driver);
  }
  
  MODULE_AUTHOR("Aurelien Jarno <aurelien@aurel32.net>");
  MODULE_DESCRIPTION("PCF8591 driver");
  MODULE_LICENSE("GPL");
  
  module_init(pcf8591_init);
  module_exit(pcf8591_exit);
  