/*
 * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
 * Copyright (c) 2012 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
 *
 * 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 <common.h>
#include <init.h>
#include <clock.h>

#include "w1.h"

static LIST_HEAD(w1_buses);

static void w1_pre_write(struct w1_bus *bus);
static void w1_post_write(struct w1_bus *bus);

static void w1_delay(unsigned long usecs)
{
	uint64_t start = get_time_ns();

	while(!is_timeout_non_interruptible(start, usecs * USECOND));
}

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
};

u8 w1_calc_crc8(u8 * data, int len)
{
	u8 crc = 0;

	while (len--)
		crc = w1_crc8_table[crc ^ *data++];

	return crc;
}

/**
 * Issues a reset bus sequence.
 *
 * @param  dev The bus master pointer
 * @return     0=Device present, 1=No device present or error
 */
int w1_reset_bus(struct w1_bus *bus)
{
	return bus->reset_bus(bus) & 0x1;
}

static u8 w1_soft_reset_bus(struct w1_bus *bus)
{
	int result;

	bus->write_bit(bus, 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);
	bus->write_bit(bus, 1);
	w1_delay(70);

	result = bus->read_bit(bus) & 0x1;
	/* minmum 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 */
	mdelay(1);

	return result;
}

/**
 * Generates a write-0 or write-1 cycle and samples the level.
 */
static u8 w1_touch_bit(struct w1_bus *bus, int bit)
{
	return bus->touch_bit(bus, bit);
}

/**
 * Generates a write-0 or write-1 cycle.
 * Only call if dev->bus_master->touch_bit is NULL
 */
static void w1_write_bit(struct w1_bus *bus, int bit)
{
	if (bit) {
		bus->write_bit(bus, 0);
		w1_delay(6);
		bus->write_bit(bus, 1);
		w1_delay(64);
	} else {
		bus->write_bit(bus, 0);
		w1_delay(60);
		bus->write_bit(bus, 1);
		w1_delay(10);
	}
}

/**
 * Reads 8 bits.
 *
 * @param dev     the master device
 * @return        the byte read
 */
u8 w1_read_8(struct w1_bus *bus)
{
	return bus->read_byte(bus);
}

static u8 w1_soft_read_8(struct w1_bus *bus)
{
	int i;
	u8 res = 0;

	for (i = 0; i < 8; ++i)
		res |= (w1_touch_bit(bus, 1) << i);

	return res;
}

/**
 * Writes a series of bytes.
 *
 * @param dev     the master device
 * @param buf     pointer to the data to write
 * @param len     the number of bytes to write
 */
void w1_write_block(struct w1_bus *bus, const u8 *buf, int len)
{
	int i;

	if (bus->write_block) {
		w1_pre_write(bus);
		bus->write_block(bus, buf, len);
	} else {
		for (i = 0; i < len; ++i)
			w1_write_8(bus, buf[i]); /* calls w1_pre_write */
	}
	w1_post_write(bus);
}

/**
 * Touches a series of bytes.
 *
 * @param dev     the master device
 * @param buf     pointer to the data to write
 * @param len     the number of bytes to write
 */
void w1_touch_block(struct w1_bus *bus, 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(bus);
			tmp |= w1_touch_bit(bus, (buf[i] >> j) & 0x1) << j;
		}

		buf[i] = tmp;
	}
}

/**
 * Generates a write-1 cycle and samples the level.
 * Only call if dev->bus_master->touch_bit is NULL
 */
static u8 w1_read_bit(struct w1_bus *bus)
{
	int result;

	/* sample timing is critical here */
	bus->write_bit(bus, 0);
	w1_delay(6);
	bus->write_bit(bus, 1);
	w1_delay(9);

	result = bus->read_bit(bus);

	w1_delay(55);

	return result & 0x1;
}

/**
 * Does a triplet - used for searching ROM addresses.
 * 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.
 *
 * @param dev     the master device
 * @param bdir    the bit to write if both id_bit and comp_bit are 0
 * @return        bit fields - see above
 */
u8 w1_triplet(struct w1_bus *bus, int bdir)
{
	return bus->triplet(bus, bdir);
}

static u8 w1_soft_triplet(struct w1_bus *bus, u8 bdir)
{
	u8 id_bit   = w1_touch_bit(bus, 1);
	u8 comp_bit = w1_touch_bit(bus, 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;
	}

	w1_touch_bit(bus, bdir);
	return retval;
}

static u8 w1_soft_touch_bit(struct w1_bus *bus, u8 bit)
{
	if (bit)
		return w1_read_bit(bus);

	w1_write_bit(bus, 0);
	return 0;
}

/**
 * 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.
 *
 * @param dev     the master device
 */
static void w1_pre_write(struct w1_bus *bus)
{
	if (!bus->set_pullup)
		return;

	if (bus->pullup_duration && bus->enable_pullup)
		bus->set_pullup(bus, bus->pullup_duration);
}

/**
 * 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.
 *
 * @param dev     the master device
 */
static void w1_post_write(struct w1_bus *bus)
{
	if (!bus->pullup_duration)
		return;

	if (bus->enable_pullup && bus->set_pullup)
		bus->set_pullup(bus, 0);
	else
		mdelay(bus->pullup_duration);
	bus->pullup_duration = 0;
}

/**
 * Writes 8 bits.
 *
 * @param dev     the master device
 * @param byte    the byte to write
 */
void w1_write_8(struct w1_bus *bus, u8 byte)
{
	if (bus->write_byte) {
		w1_pre_write(bus);
		bus->write_byte(bus, byte);
	} else {
		int i;

		for (i = 0; i < 8; ++i) {
			if (i == 7)
				w1_pre_write(bus);
			w1_touch_bit(bus, (byte >> i) & 0x1);
		}
	}
	w1_post_write(bus);
}

/**
 * Reads a series of bytes.
 *
 * @param dev     the master device
 * @param buf     pointer to the buffer to fill
 * @param len     the number of bytes to read
 * @return        the number of bytes read
 */
u8 w1_read_block(struct w1_bus *bus, u8 *buf, int len)
{
	return bus->read_block(bus, buf, len);
}

static u8 w1_soft_read_block(struct w1_bus *bus, u8 *buf, int len)
{
	int i;

	for (i = 0; i < len; ++i)
		buf[i] = w1_read_8(bus);
	return len;
}

/**
 * Resets the bus and then selects the slave by sending either a skip rom
 * or a rom match.
 * The w1 master lock must be held.
 *
 * @param sl	the slave to select
 * @return 	0=success, anything else=error
 */
int w1_reset_select_slave(struct w1_device *dev)
{
	struct w1_bus *bus = dev->bus;

	if (w1_reset_bus(bus))
		return -1;

	if (bus->slave_count == 1)
		w1_write_8(bus, W1_SKIP_ROM);
	else {
		u8 match[9] = {W1_MATCH_ROM, };
		u64 rn = le64_to_cpu(*((u64*)&dev->reg_num));

		memcpy(&match[1], &rn, 8);
		w1_write_block(bus, match, 9);
	}
	return 0;
}

#define to_w1_device(d)	container_of(d, struct w1_device, dev)
#define to_w1_driver(d) container_of(d, struct w1_driver, drv)

static int w1_bus_match(struct device_d *_dev, struct driver_d *_drv)
{
	struct w1_device *dev = to_w1_device(_dev);
	struct w1_driver *drv = to_w1_driver(_drv);

	return !(drv->fid == dev->fid);
}

static int w1_bus_probe(struct device_d *_dev)
{
	struct w1_driver *drv = to_w1_driver(_dev->driver);
	struct w1_device *dev = to_w1_device(_dev);

	return drv->probe(dev);
}

static void w1_bus_remove(struct device_d *_dev)
{
	struct w1_driver *drv = to_w1_driver(_dev->driver);
	struct w1_device *dev = to_w1_device(_dev);

	if (drv->remove)
		drv->remove(dev);
}

struct bus_type w1_bustype= {
	.name = "w1_bus",
	.match = w1_bus_match,
	.probe = w1_bus_probe,
	.remove = w1_bus_remove,
};

static bool w1_is_registered(struct w1_bus *bus, u64 rn)
{
	struct device_d *dev = NULL;
	struct w1_device *w1_dev;

	bus_for_each_device(&w1_bustype, dev) {
		w1_dev = to_w1_device(dev);

		if (w1_dev->bus == bus && w1_dev->reg_num == rn)
			return true;
	}

	return false;
}

static int w1_device_register(struct w1_bus *bus, struct w1_device *dev)
{
	char str[18];
	int ret;

	dev_set_name(&dev->dev, "w1-%x-", dev->fid);
	dev->dev.id = DEVICE_ID_DYNAMIC;
	dev->dev.bus = &w1_bustype;
	dev->bus = bus;

	dev->dev.parent = &bus->dev;

	ret = register_device(&dev->dev);
	if (ret)
		return ret;

	sprintf(str, "0x%x", dev->fid);
	dev_add_param_fixed(&dev->dev, "fid", str);
	sprintf(str, "0x%llx", dev->id);
	dev_add_param_fixed(&dev->dev, "id", str);
	sprintf(str, "0x%llx", dev->reg_num);
	dev_add_param_fixed(&dev->dev, "reg_num", str);

	return ret;
}

int w1_driver_register(struct w1_driver *drv)
{
	drv->drv.bus = &w1_bustype;

	if (drv->probe)
		drv->drv.probe = w1_bus_probe;
	if (drv->remove)
		drv->drv.remove = w1_bus_remove;

	return register_driver(&drv->drv);
}

static void w1_found(struct w1_bus *bus, u64 rn)
{
	struct w1_device *dev;
	u64 tmp = be64_to_cpu(rn);

	if (IS_ENABLED(CONFIG_W1_DUAL_SEARCH)
	 && bus->is_searched && w1_is_registered(bus, rn))
		return;

	dev = xzalloc(sizeof(*dev));

	dev->reg_num = rn;
	dev->fid = tmp >> 56;
	dev->id = (tmp >> 8) & 0xffffffffffffULL;
	dev->crc = tmp & 0xff;

	dev_dbg(&bus->dev, "%s:  familly = 0x%x, id = 0x%llx, crc = 0x%x\n",
		__func__, dev->fid, dev->id, dev->crc);

	if (dev->crc != w1_calc_crc8((u8 *)&rn, 7)) {
		dev_err(&bus->dev, "0x%llx crc error\n", rn);
		return;
	}

	w1_device_register(bus, dev);
}

/**
 * Performs a ROM Search & registers any devices found.
 * The 1-wire search is a simple binary tree search.
 * For each bit of the address, we read two bits and write one bit.
 * The bit written will put to sleep all devies that don't match that bit.
 * When the two reads differ, the direction choice is obvious.
 * When both bits are 0, we must choose a path to take.
 * When we can scan all 64 bits without having to choose a path, we are done.
 *
 * See "Application note 187 1-wire search algorithm" at www.maxim-ic.com
 *
 * @dev        The master device to search
 * @cb         Function to call when a device is found
 */
static void w1_search(struct w1_bus *bus, u8 search_type)
{
	u64 last_rn, rn, tmp64;
	int i, slave_count = 0;
	int last_zero, last_device;
	int search_bit, desc_bit;
	u8  triplet_ret = 0;

	search_bit = 0;
	rn = last_rn = 0;
	last_device = 0;
	last_zero = -1;

	desc_bit = 64;

	while ( !last_device && (slave_count++ < bus->max_slave_count) ) {
		last_rn = rn;
		rn = 0;

		/*
		 * Reset bus and all 1-wire device state machines
		 * so they can respond to our requests.
		 *
		 * Return 0 - device(s) present, 1 - no devices present.
		 */
		if (w1_reset_bus(bus)) {
			dev_dbg(&bus->dev, "No devices present on the wire.\n");
			break;
		}

		/* Do fast search on single slave bus */
		if (bus->max_slave_count == 1) {
			int rv;
			w1_write_8(bus, W1_READ_ROM);
			rv = w1_read_block(bus, (u8 *)&rn, 8);

			if (rv == 8 && rn)
				w1_found(bus, rn);

			break;
		}

		/* Start the search */
		w1_write_8(bus, search_type);
		for (i = 0; i < 64; ++i) {
			/* Determine the direction/search bit */
			if (i == desc_bit)
				search_bit = 1;	  /* took the 0 path last time, so take the 1 path */
			else if (i > desc_bit)
				search_bit = 0;	  /* take the 0 path on the next branch */
			else
				search_bit = ((last_rn >> i) & 0x1);

			/** Read two bits and write one bit */
			triplet_ret = w1_triplet(bus, search_bit);

			/* quit if no device responded */
			if ( (triplet_ret & 0x03) == 0x03 )
				break;

			/* If both directions were valid, and we took the 0 path... */
			if (triplet_ret == 0)
				last_zero = i;

			/* extract the direction taken & update the device number */
			tmp64 = (triplet_ret >> 2);
			rn |= (tmp64 << i);
		}

		if ( (triplet_ret & 0x03) != 0x03 ) {
			if ( (desc_bit == last_zero) || (last_zero < 0))
				last_device = 1;
			desc_bit = last_zero;
			w1_found(bus, rn);
		}
	}

	w1_reset_bus(bus);
}

int w1_bus_register(struct w1_bus *bus)
{
	int ret;

	/* validate minimum functionality */
	if (!(bus->touch_bit && bus->reset_bus) &&
	    !(bus->write_bit && bus->read_bit)) {
		pr_err("w1_bus_register: invalid function set\n");
		return -EINVAL;
	}
	/* While it would be electrically possible to make a device that
	 * generated a strong pullup in bit bang mode, only hardware that
	 * controls 1-wire time frames are even expected to support a strong
	 * pullup.  w1_io.c would need to support calling set_pullup before
	 * the last write_bit operation of a w1_write_8 which it currently
	 * doesn't.
	 */
	if (!bus->touch_bit && bus->set_pullup) {
		pr_err("w1_add_bus_device: set_pullup requires touch_bit, disabling\n");
		bus->set_pullup = NULL;
	}

	if (!bus->reset_bus)
		bus->reset_bus = w1_soft_reset_bus;

	if (!bus->touch_bit)
		bus->touch_bit = w1_soft_touch_bit;

	if (!bus->read_block)
		bus->read_block = w1_soft_read_block;

	if (!bus->read_byte)
		bus->read_byte = w1_soft_read_8;

	if (!bus->triplet)
		bus->triplet = w1_soft_triplet;

	if (!bus->max_slave_count)
		bus->max_slave_count = 10;

	list_add_tail(&bus->list, &w1_buses);

	dev_set_name(&bus->dev, "w1_bus");
	bus->dev.id = DEVICE_ID_DYNAMIC;
	bus->dev.parent = bus->parent;

	ret = register_device(&bus->dev);
	if (ret)
		return ret;

	bus->is_searched = false;
	w1_search(bus, W1_SEARCH);
	bus->is_searched = true;
	if (IS_ENABLED(CONFIG_W1_DUAL_SEARCH))
		w1_search(bus, W1_SEARCH);

	return 0;
}

static int w1_bus_init(void)
{
	return bus_register(&w1_bustype);
}
pure_initcall(w1_bus_init);
