text: /*
   * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   */
  
  #include <asm/io.h>
  
  #include <linux/delay.h>
  #include <linux/moduleparam.h>
  #include <linux/module.h>
  
  #include "w1_internal.h"
  
  static int w1_delay_parm = 1;
  module_param_named(delay_coef, w1_delay_parm, int, 0);
  
  static int w1_disable_irqs = 0;
  module_param_named(disable_irqs, w1_disable_irqs, int, 0);
  
  static u8 w1_crc8_table[] = {
  	0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65,
  	157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220,
  	35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98,
  	190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255,
  	70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89, 7,
  	219, 133, 103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196, 154,
  	101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36,
  	248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231, 185,
  	140, 210, 48, 110, 237, 179, 81, 15, 78, 16, 242, 172, 47, 113, 147, 205,
  	17, 79, 173, 243, 112, 46, 204, 146, 211, 141, 111, 49, 178, 236, 14, 80,
  	175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82, 176, 238,
  	50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115,
  	202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213, 139,
  	87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22,
  	233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168,
  	116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53
  };
  
  static void w1_delay(unsigned long tm)
  {
  	udelay(tm * w1_delay_parm);
  }
  
  static void w1_write_bit(struct w1_master *dev, int bit);
  static u8 w1_read_bit(struct w1_master *dev);
  
  /**
   * w1_touch_bit() - Generates a write-0 or write-1 cycle and samples the level.
   * @dev:	the master device
   * @bit:	0 - write a 0, 1 - write a 0 read the level
   */
  static u8 w1_touch_bit(struct w1_master *dev, int bit)
  {
  	if (dev->bus_master->touch_bit)
  		return dev->bus_master->touch_bit(dev->bus_master->data, bit);
  	else if (bit)
  		return w1_read_bit(dev);
  	else {
  		w1_write_bit(dev, 0);
  		return 0;
  	}
  }
  
  /**
   * w1_write_bit() - Generates a write-0 or write-1 cycle.
   * @dev:	the master device
   * @bit:	bit to write
   *
   * Only call if dev->bus_master->touch_bit is NULL
   */
  static void w1_write_bit(struct w1_master *dev, int bit)
  {
  	unsigned long flags = 0;
  
  	if(w1_disable_irqs) local_irq_save(flags);
  
  	if (bit) {
  		dev->bus_master->write_bit(dev->bus_master->data, 0);
  		w1_delay(6);
  		dev->bus_master->write_bit(dev->bus_master->data, 1);
  		w1_delay(64);
  	} else {
  		dev->bus_master->write_bit(dev->bus_master->data, 0);
  		w1_delay(60);
  		dev->bus_master->write_bit(dev->bus_master->data, 1);
  		w1_delay(10);
  	}
  
  	if(w1_disable_irqs) local_irq_restore(flags);
  }
  
  /**
   * w1_pre_write() - pre-write operations
   * @dev:	the master device
   *
   * Pre-write operation, currently only supporting strong pullups.
   * Program the hardware for a strong pullup, if one has been requested and
   * the hardware supports it.
   */
  static void w1_pre_write(struct w1_master *dev)
  {
  	if (dev->pullup_duration &&
  		dev->enable_pullup && dev->bus_master->set_pullup) {
  		dev->bus_master->set_pullup(dev->bus_master->data,
  			dev->pullup_duration);
  	}
  }
  
  /**
   * w1_post_write() - post-write options
   * @dev:	the master device
   *
   * Post-write operation, currently only supporting strong pullups.
   * If a strong pullup was requested, clear it if the hardware supports
   * them, or execute the delay otherwise, in either case clear the request.
   */
  static void w1_post_write(struct w1_master *dev)
  {
  	if (dev->pullup_duration) {
  		if (dev->enable_pullup && dev->bus_master->set_pullup)
  			dev->bus_master->set_pullup(dev->bus_master->data, 0);
  		else
  			msleep(dev->pullup_duration);
  		dev->pullup_duration = 0;
  	}
  }
  
  /**
   * w1_write_8() - Writes 8 bits.
   * @dev:	the master device
   * @byte:	the byte to write
   */
  void w1_write_8(struct w1_master *dev, u8 byte)
  {
  	int i;
  
  	if (dev->bus_master->write_byte) {
  		w1_pre_write(dev);
  		dev->bus_master->write_byte(dev->bus_master->data, byte);
  	}
  	else
  		for (i = 0; i < 8; ++i) {
  			if (i == 7)
  				w1_pre_write(dev);
  			w1_touch_bit(dev, (byte >> i) & 0x1);
  		}
  	w1_post_write(dev);
  }
  EXPORT_SYMBOL_GPL(w1_write_8);
  
  
  /**
   * w1_read_bit() - Generates a write-1 cycle and samples the level.
   * @dev:	the master device
   *
   * Only call if dev->bus_master->touch_bit is NULL
   */
  static u8 w1_read_bit(struct w1_master *dev)
  {
  	int result;
  	unsigned long flags = 0;
  
  	/* sample timing is critical here */
  	local_irq_save(flags);
  	dev->bus_master->write_bit(dev->bus_master->data, 0);
  	w1_delay(6);
  	dev->bus_master->write_bit(dev->bus_master->data, 1);
  	w1_delay(9);
  
  	result = dev->bus_master->read_bit(dev->bus_master->data);
  	local_irq_restore(flags);
  
  	w1_delay(55);
  
  	return result & 0x1;
  }
  
  /**
   * w1_triplet() - * Does a triplet - used for searching ROM addresses.
   * @dev:	the master device
   * @bdir:	the bit to write if both id_bit and comp_bit are 0
   *
   * Return bits:
   *  bit 0 = id_bit
   *  bit 1 = comp_bit
   *  bit 2 = dir_taken
   * If both bits 0 & 1 are set, the search should be restarted.
   *
   * Return:        bit fields - see above
   */
  u8 w1_triplet(struct w1_master *dev, int bdir)
  {
  	if (dev->bus_master->triplet)
  		return dev->bus_master->triplet(dev->bus_master->data, bdir);
  	else {
  		u8 id_bit   = w1_touch_bit(dev, 1);
  		u8 comp_bit = w1_touch_bit(dev, 1);
  		u8 retval;
  
  		if (id_bit && comp_bit)
  			return 0x03;  /* error */
  
  		if (!id_bit && !comp_bit) {
  			/* Both bits are valid, take the direction given */
  			retval = bdir ? 0x04 : 0;
  		} else {
  			/* Only one bit is valid, take that direction */
  			bdir = id_bit;
  			retval = id_bit ? 0x05 : 0x02;
  		}
  
  		if (dev->bus_master->touch_bit)
  			w1_touch_bit(dev, bdir);
  		else
  			w1_write_bit(dev, bdir);
  		return retval;
  	}
  }
  EXPORT_SYMBOL_GPL(w1_triplet);
  
  /**
   * w1_read_8() - Reads 8 bits.
   * @dev:	the master device
   *
   * Return:        the byte read
   */
  u8 w1_read_8(struct w1_master *dev)
  {
  	int i;
  	u8 res = 0;
  
  	if (dev->bus_master->read_byte)
  		res = dev->bus_master->read_byte(dev->bus_master->data);
  	else
  		for (i = 0; i < 8; ++i)
  			res |= (w1_touch_bit(dev,1) << i);
  
  	return res;
  }
  EXPORT_SYMBOL_GPL(w1_read_8);
  
  /**
   * w1_write_block() - Writes a series of bytes.
   * @dev:	the master device
   * @buf:	pointer to the data to write
   * @len:	the number of bytes to write
   */
  void w1_write_block(struct w1_master *dev, const u8 *buf, int len)
  {
  	int i;
  
  	if (dev->bus_master->write_block) {
  		w1_pre_write(dev);
  		dev->bus_master->write_block(dev->bus_master->data, buf, len);
  	}
  	else
  		for (i = 0; i < len; ++i)
  			w1_write_8(dev, buf[i]); /* calls w1_pre_write */
  	w1_post_write(dev);
  }
  EXPORT_SYMBOL_GPL(w1_write_block);
  
  /**
   * w1_touch_block() - Touches a series of bytes.
   * @dev:	the master device
   * @buf:	pointer to the data to write
   * @len:	the number of bytes to write
   */
  void w1_touch_block(struct w1_master *dev, u8 *buf, int len)
  {
  	int i, j;
  	u8 tmp;
  
  	for (i = 0; i < len; ++i) {
  		tmp = 0;
  		for (j = 0; j < 8; ++j) {
  			if (j == 7)
  				w1_pre_write(dev);
  			tmp |= w1_touch_bit(dev, (buf[i] >> j) & 0x1) << j;
  		}
  
  		buf[i] = tmp;
  	}
  }
  EXPORT_SYMBOL_GPL(w1_touch_block);
  
  /**
   * w1_read_block() - Reads a series of bytes.
   * @dev:	the master device
   * @buf:	pointer to the buffer to fill
   * @len:	the number of bytes to read
   * Return:	the number of bytes read
   */
  u8 w1_read_block(struct w1_master *dev, u8 *buf, int len)
  {
  	int i;
  	u8 ret;
  
  	if (dev->bus_master->read_block)
  		ret = dev->bus_master->read_block(dev->bus_master->data, buf, len);
  	else {
  		for (i = 0; i < len; ++i)
  			buf[i] = w1_read_8(dev);
  		ret = len;
  	}
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(w1_read_block);
  
  /**
   * w1_reset_bus() - Issues a reset bus sequence.
   * @dev:	the master device
   * Return:	0=Device present, 1=No device present or error
   */
  int w1_reset_bus(struct w1_master *dev)
  {
  	int result;
  	unsigned long flags = 0;
  
  	if(w1_disable_irqs) local_irq_save(flags);
  
  	if (dev->bus_master->reset_bus)
  		result = dev->bus_master->reset_bus(dev->bus_master->data) & 0x1;
  	else {
  		dev->bus_master->write_bit(dev->bus_master->data, 0);
  		/* minimum 480, max ? us
  		 * be nice and sleep, except 18b20 spec lists 960us maximum,
  		 * so until we can sleep with microsecond accuracy, spin.
  		 * Feel free to come up with some other way to give up the
  		 * cpu for such a short amount of time AND get it back in
  		 * the maximum amount of time.
  		 */
  		w1_delay(500);
  		dev->bus_master->write_bit(dev->bus_master->data, 1);
  		w1_delay(70);
  
  		result = dev->bus_master->read_bit(dev->bus_master->data) & 0x1;
  		/* minimum 70 (above) + 430 = 500 us
  		 * There aren't any timing requirements between a reset and
  		 * the following transactions.  Sleeping is safe here.
  		 */
  		/* w1_delay(430); min required time */
  		msleep(1);
  	}
  
  	if(w1_disable_irqs) local_irq_restore(flags);
  
  	return result;
  }
  EXPORT_SYMBOL_GPL(w1_reset_bus);
  
  u8 w1_calc_crc8(u8 * data, int len)
  {
  	u8 crc = 0;
  
  	while (len--)
  		crc = w1_crc8_table[crc ^ *data++];
  
  	return crc;
  }
  EXPORT_SYMBOL_GPL(w1_calc_crc8);
  
  void w1_search_devices(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb)
  {
  	dev->attempts++;
  	if (dev->bus_master->search)
  		dev->bus_master->search(dev->bus_master->data, dev,
  			search_type, cb);
  	else
  		w1_search(dev, search_type, cb);
  }
  
  /**
   * w1_reset_select_slave() - reset and select a slave
   * @sl:		the slave to select
   *
   * Resets the bus and then selects the slave by sending either a skip rom
   * or a rom match.  A skip rom is issued if there is only one device
   * registered on the bus.
   * The w1 master lock must be held.
   *
   * Return:	0=success, anything else=error
   */
  int w1_reset_select_slave(struct w1_slave *sl)
  {
  	if (w1_reset_bus(sl->master))
  		return -1;
  
  	if (sl->master->slave_count == 1)
  		w1_write_8(sl->master, W1_SKIP_ROM);
  	else {
  		u8 match[9] = {W1_MATCH_ROM, };
  		u64 rn = le64_to_cpu(*((u64*)&sl->reg_num));
  
  		memcpy(&match[1], &rn, 8);
  		w1_write_block(sl->master, match, 9);
  	}
  	return 0;
  }
  EXPORT_SYMBOL_GPL(w1_reset_select_slave);
  
  /**
   * w1_reset_resume_command() - resume instead of another match ROM
   * @dev:	the master device
   *
   * When the workflow with a slave amongst many requires several
   * successive commands a reset between each, this function is similar
   * to doing a reset then a match ROM for the last matched ROM. The
   * advantage being that the matched ROM step is skipped in favor of the
   * resume command. The slave must support the command of course.
   *
   * If the bus has only one slave, traditionnaly the match ROM is skipped
   * and a "SKIP ROM" is done for efficiency. On multi-slave busses, this
   * doesn't work of course, but the resume command is the next best thing.
   *
   * The w1 master lock must be held.
   */
  int w1_reset_resume_command(struct w1_master *dev)
  {
  	if (w1_reset_bus(dev))
  		return -1;
  
  	/* This will make only the last matched slave perform a skip ROM. */
  	w1_write_8(dev, W1_RESUME_CMD);
  	return 0;
  }
  EXPORT_SYMBOL_GPL(w1_reset_resume_command);
  
  /**
   * w1_next_pullup() - register for a strong pullup
   * @dev:	the master device
   * @delay:	time in milliseconds
   *
   * Put out a strong pull-up of the specified duration after the next write
   * operation.  Not all hardware supports strong pullups.  Hardware that
   * doesn't support strong pullups will sleep for the given time after the
   * write operation without a strong pullup.  This is a one shot request for
   * the next write, specifying zero will clear a previous request.
   * The w1 master lock must be held.
   *
   * Return:	0=success, anything else=error
   */
  void w1_next_pullup(struct w1_master *dev, int delay)
  {
  	dev->pullup_duration = delay;
  }
  EXPORT_SYMBOL_GPL(w1_next_pullup);
  