/*
   * Copyright 2007-2008 Extreme Engineering Solutions, Inc.
   *
   * Author: Nate Case <ncase@xes-inc.com>
   *
   * This file is subject to the terms and conditions of version 2 of
   * the GNU General Public License.  See the file COPYING in the main
   * directory of this archive for more details.
   *
   * LED driver for various PCA955x I2C LED drivers
   *
   * Supported devices:
   *
   *	Device		Description		7-bit slave address
   *	------		-----------		-------------------
   *	PCA9550		2-bit driver		0x60 .. 0x61
   *	PCA9551		8-bit driver		0x60 .. 0x67
   *	PCA9552		16-bit driver		0x60 .. 0x67
   *	PCA9553/01	4-bit driver		0x62
   *	PCA9553/02	4-bit driver		0x63
   *
   * Philips PCA955x LED driver chips follow a register map as shown below:
   *
   *	Control Register		Description
   *	----------------		-----------
   *	0x0				Input register 0
   *					..
   *	NUM_INPUT_REGS - 1		Last Input register X
   *
   *	NUM_INPUT_REGS			Frequency prescaler 0
   *	NUM_INPUT_REGS + 1		PWM register 0
   *	NUM_INPUT_REGS + 2		Frequency prescaler 1
   *	NUM_INPUT_REGS + 3		PWM register 1
   *
   *	NUM_INPUT_REGS + 4		LED selector 0
   *	NUM_INPUT_REGS + 4
   *	    + NUM_LED_REGS - 1		Last LED selector
   *
   *  where NUM_INPUT_REGS and NUM_LED_REGS vary depending on how many
   *  bits the chip supports.
   */
  
  #include <linux/module.h>
  #include <linux/delay.h>
  #include <linux/string.h>
  #include <linux/ctype.h>
  #include <linux/leds.h>
  #include <linux/err.h>
  #include <linux/i2c.h>
  #include <linux/workqueue.h>
  #include <linux/slab.h>
  
  /* LED select registers determine the source that drives LED outputs */
  #define PCA955X_LS_LED_ON	0x0	/* Output LOW */
  #define PCA955X_LS_LED_OFF	0x1	/* Output HI-Z */
  #define PCA955X_LS_BLINK0	0x2	/* Blink at PWM0 rate */
  #define PCA955X_LS_BLINK1	0x3	/* Blink at PWM1 rate */
  
  enum pca955x_type {
  	pca9550,
  	pca9551,
  	pca9552,
  	pca9553,
  };
  
  struct pca955x_chipdef {
  	int			bits;
  	u8			slv_addr;	/* 7-bit slave address mask */
  	int			slv_addr_shift;	/* Number of bits to ignore */
  };
  
  static struct pca955x_chipdef pca955x_chipdefs[] = {
  	[pca9550] = {
  		.bits		= 2,
  		.slv_addr	= /* 110000x */ 0x60,
  		.slv_addr_shift	= 1,
  	},
  	[pca9551] = {
  		.bits		= 8,
  		.slv_addr	= /* 1100xxx */ 0x60,
  		.slv_addr_shift	= 3,
  	},
  	[pca9552] = {
  		.bits		= 16,
  		.slv_addr	= /* 1100xxx */ 0x60,
  		.slv_addr_shift	= 3,
  	},
  	[pca9553] = {
  		.bits		= 4,
  		.slv_addr	= /* 110001x */ 0x62,
  		.slv_addr_shift	= 1,
  	},
  };
  
  static const struct i2c_device_id pca955x_id[] = {
  	{ "pca9550", pca9550 },
  	{ "pca9551", pca9551 },
  	{ "pca9552", pca9552 },
  	{ "pca9553", pca9553 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, pca955x_id);
  
  struct pca955x {
  	struct mutex lock;
  	struct pca955x_led *leds;
  	struct pca955x_chipdef	*chipdef;
  	struct i2c_client	*client;
  };
  
  struct pca955x_led {
  	struct pca955x	*pca955x;
  	struct work_struct	work;
  	enum led_brightness	brightness;
  	struct led_classdev	led_cdev;
  	int			led_num;	/* 0 .. 15 potentially */
  	char			name[32];
  };
  
  /* 8 bits per input register */
  static inline int pca95xx_num_input_regs(int bits)
  {
  	return (bits + 7) / 8;
  }
  
  /* 4 bits per LED selector register */
  static inline int pca95xx_num_led_regs(int bits)
  {
  	return (bits + 3)  / 4;
  }
  
  /*
   * Return an LED selector register value based on an existing one, with
   * the appropriate 2-bit state value set for the given LED number (0-3).
   */
  static inline u8 pca955x_ledsel(u8 oldval, int led_num, int state)
  {
  	return (oldval & (~(0x3 << (led_num << 1)))) |
  		((state & 0x3) << (led_num << 1));
  }
  
  /*
   * Write to frequency prescaler register, used to program the
   * period of the PWM output.  period = (PSCx + 1) / 38
   */
  static void pca955x_write_psc(struct i2c_client *client, int n, u8 val)
  {
  	struct pca955x *pca955x = i2c_get_clientdata(client);
  
  	i2c_smbus_write_byte_data(client,
  		pca95xx_num_input_regs(pca955x->chipdef->bits) + 2*n,
  		val);
  }
  
  /*
   * Write to PWM register, which determines the duty cycle of the
   * output.  LED is OFF when the count is less than the value of this
   * register, and ON when it is greater.  If PWMx == 0, LED is always OFF.
   *
   * Duty cycle is (256 - PWMx) / 256
   */
  static void pca955x_write_pwm(struct i2c_client *client, int n, u8 val)
  {
  	struct pca955x *pca955x = i2c_get_clientdata(client);
  
  	i2c_smbus_write_byte_data(client,
  		pca95xx_num_input_regs(pca955x->chipdef->bits) + 1 + 2*n,
  		val);
  }
  
  /*
   * Write to LED selector register, which determines the source that
   * drives the LED output.
   */
  static void pca955x_write_ls(struct i2c_client *client, int n, u8 val)
  {
  	struct pca955x *pca955x = i2c_get_clientdata(client);
  
  	i2c_smbus_write_byte_data(client,
  		pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n,
  		val);
  }
  
  /*
   * Read the LED selector register, which determines the source that
   * drives the LED output.
   */
  static u8 pca955x_read_ls(struct i2c_client *client, int n)
  {
  	struct pca955x *pca955x = i2c_get_clientdata(client);
  
  	return (u8) i2c_smbus_read_byte_data(client,
  		pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n);
  }
  
  static void pca955x_led_work(struct work_struct *work)
  {
  	struct pca955x_led *pca955x_led;
  	struct pca955x *pca955x;
  	u8 ls;
  	int chip_ls;	/* which LSx to use (0-3 potentially) */
  	int ls_led;	/* which set of bits within LSx to use (0-3) */
  
  	pca955x_led = container_of(work, struct pca955x_led, work);
  	pca955x = pca955x_led->pca955x;
  
  	chip_ls = pca955x_led->led_num / 4;
  	ls_led = pca955x_led->led_num % 4;
  
  	mutex_lock(&pca955x->lock);
  
  	ls = pca955x_read_ls(pca955x->client, chip_ls);
  
  	switch (pca955x_led->brightness) {
  	case LED_FULL:
  		ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_ON);
  		break;
  	case LED_OFF:
  		ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_OFF);
  		break;
  	case LED_HALF:
  		ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK0);
  		break;
  	default:
  		/*
  		 * Use PWM1 for all other values.  This has the unwanted
  		 * side effect of making all LEDs on the chip share the
  		 * same brightness level if set to a value other than
  		 * OFF, HALF, or FULL.  But, this is probably better than
  		 * just turning off for all other values.
  		 */
  		pca955x_write_pwm(pca955x->client, 1,
  				255 - pca955x_led->brightness);
  		ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK1);
  		break;
  	}
  
  	pca955x_write_ls(pca955x->client, chip_ls, ls);
  
  	mutex_unlock(&pca955x->lock);
  }
  
  static void pca955x_led_set(struct led_classdev *led_cdev, enum led_brightness value)
  {
  	struct pca955x_led *pca955x;
  
  	pca955x = container_of(led_cdev, struct pca955x_led, led_cdev);
  
  	pca955x->brightness = value;
  
  	/*
  	 * Must use workqueue for the actual I/O since I2C operations
  	 * can sleep.
  	 */
  	schedule_work(&pca955x->work);
  }
  
  static int pca955x_probe(struct i2c_client *client,
  					const struct i2c_device_id *id)
  {
  	struct pca955x *pca955x;
  	struct pca955x_led *pca955x_led;
  	struct pca955x_chipdef *chip;
  	struct i2c_adapter *adapter;
  	struct led_platform_data *pdata;
  	int i, err;
  
  	chip = &pca955x_chipdefs[id->driver_data];
  	adapter = to_i2c_adapter(client->dev.parent);
  	pdata = dev_get_platdata(&client->dev);
  
  	/* Make sure the slave address / chip type combo given is possible */
  	if ((client->addr & ~((1 << chip->slv_addr_shift) - 1)) !=
  	    chip->slv_addr) {
  		dev_err(&client->dev, "invalid slave address %02x
  ",
  				client->addr);
  		return -ENODEV;
  	}
  
  	dev_info(&client->dev, "leds-pca955x: Using %s %d-bit LED driver at "
  			"slave address 0x%02x
  ",
  			id->name, chip->bits, client->addr);
  
  	if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
  		return -EIO;
  
  	if (pdata) {
  		if (pdata->num_leds != chip->bits) {
  			dev_err(&client->dev, "board info claims %d LEDs"
  					" on a %d-bit chip
  ",
  					pdata->num_leds, chip->bits);
  			return -ENODEV;
  		}
  	}
  
  	pca955x = devm_kzalloc(&client->dev, sizeof(*pca955x), GFP_KERNEL);
  	if (!pca955x)
  		return -ENOMEM;
  
  	pca955x->leds = devm_kzalloc(&client->dev,
  			sizeof(*pca955x_led) * chip->bits, GFP_KERNEL);
  	if (!pca955x->leds)
  		return -ENOMEM;
  
  	i2c_set_clientdata(client, pca955x);
  
  	mutex_init(&pca955x->lock);
  	pca955x->client = client;
  	pca955x->chipdef = chip;
  
  	for (i = 0; i < chip->bits; i++) {
  		pca955x_led = &pca955x->leds[i];
  		pca955x_led->led_num = i;
  		pca955x_led->pca955x = pca955x;
  
  		/* Platform data can specify LED names and default triggers */
  		if (pdata) {
  			if (pdata->leds[i].name)
  				snprintf(pca955x_led->name,
  					sizeof(pca955x_led->name), "pca955x:%s",
  					pdata->leds[i].name);
  			if (pdata->leds[i].default_trigger)
  				pca955x_led->led_cdev.default_trigger =
  					pdata->leds[i].default_trigger;
  		} else {
  			snprintf(pca955x_led->name, sizeof(pca955x_led->name),
  				 "pca955x:%d", i);
  		}
  
  		pca955x_led->led_cdev.name = pca955x_led->name;
  		pca955x_led->led_cdev.brightness_set = pca955x_led_set;
  
  		INIT_WORK(&pca955x_led->work, pca955x_led_work);
  
  		err = led_classdev_register(&client->dev,
  					&pca955x_led->led_cdev);
  		if (err < 0)
  			goto exit;
  	}
  
  	/* Turn off LEDs */
  	for (i = 0; i < pca95xx_num_led_regs(chip->bits); i++)
  		pca955x_write_ls(client, i, 0x55);
  
  	/* PWM0 is used for half brightness or 50% duty cycle */
  	pca955x_write_pwm(client, 0, 255-LED_HALF);
  
  	/* PWM1 is used for variable brightness, default to OFF */
  	pca955x_write_pwm(client, 1, 0);
  
  	/* Set to fast frequency so we do not see flashing */
  	pca955x_write_psc(client, 0, 0);
  	pca955x_write_psc(client, 1, 0);
  
  	return 0;
  
  exit:
  	while (i--) {
  		led_classdev_unregister(&pca955x->leds[i].led_cdev);
  		cancel_work_sync(&pca955x->leds[i].work);
  	}
  
  	return err;
  }
  
  static int pca955x_remove(struct i2c_client *client)
  {
  	struct pca955x *pca955x = i2c_get_clientdata(client);
  	int i;
  
  	for (i = 0; i < pca955x->chipdef->bits; i++) {
  		led_classdev_unregister(&pca955x->leds[i].led_cdev);
  		cancel_work_sync(&pca955x->leds[i].work);
  	}
  
  	return 0;
  }
  
  static struct i2c_driver pca955x_driver = {
  	.driver = {
  		.name	= "leds-pca955x",
  		.owner	= THIS_MODULE,
  	},
  	.probe	= pca955x_probe,
  	.remove	= pca955x_remove,
  	.id_table = pca955x_id,
  };
  
  module_i2c_driver(pca955x_driver);
  
  MODULE_AUTHOR("Nate Case <ncase@xes-inc.com>");
  MODULE_DESCRIPTION("PCA955x LED driver");
  MODULE_LICENSE("GPL v2");