w1: new driver. DS2431 chip

/*

 * w1_ds2431.c - w1 family 2d (DS2431) driver

 *

 * Copyright (c) 2008 Bernhard Weirich <bernhard.weirich@riedel.net>

 *

 * Heavily inspired by w1_DS2433 driver from Ben Gardner <bgardner@wabtec.com>

 *

 * This source code is licensed under the GNU General Public License,

 * Version 2. See the file COPYING for more details.

 */

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/moduleparam.h>

#include <linux/device.h>

#include <linux/types.h>

#include <linux/delay.h>

#include "../w1.h"

#include "../w1_int.h"

#include "../w1_family.h"

#define W1_F2D_EEPROM_SIZE		128

#define W1_F2D_PAGE_COUNT		4

#define W1_F2D_PAGE_BITS		5

#define W1_F2D_PAGE_SIZE		(1<<W1_F2D_PAGE_BITS)

#define W1_F2D_PAGE_MASK		0x1F

#define W1_F2D_SCRATCH_BITS  3

#define W1_F2D_SCRATCH_SIZE  (1<<W1_F2D_SCRATCH_BITS)

#define W1_F2D_SCRATCH_MASK  (W1_F2D_SCRATCH_SIZE-1)

#define W1_F2D_READ_EEPROM	0xF0

#define W1_F2D_WRITE_SCRATCH	0x0F

#define W1_F2D_READ_SCRATCH	0xAA

#define W1_F2D_COPY_SCRATCH	0x55

#define W1_F2D_TPROG_MS		11

#define W1_F2D_READ_RETRIES		10

#define W1_F2D_READ_MAXLEN		8

/*

 * Check the file size bounds and adjusts count as needed.

 * This would not be needed if the file size didn't reset to 0 after a write.

 */

static inline size_t w1_f2d_fix_count(loff_t off, size_t count, size_t size)

{

	if (off > size)

		return 0;

	if ((off + count) > size)

		return size - off;

	return count;

}

/*

 * Read a block from W1 ROM two times and compares the results.

 * If they are equal they are returned, otherwise the read

 * is repeated W1_F2D_READ_RETRIES times.

 *

 * count must not exceed W1_F2D_READ_MAXLEN.

 */

static int w1_f2d_readblock(struct w1_slave *sl, int off, int count, char *buf)

{

	u8 wrbuf[3];

	u8 cmp[W1_F2D_READ_MAXLEN];

	int tries = W1_F2D_READ_RETRIES;

	do {

		wrbuf[0] = W1_F2D_READ_EEPROM;

		wrbuf[1] = off & 0xff;

		wrbuf[2] = off >> 8;

		if (w1_reset_select_slave(sl))

			return -1;

		w1_write_block(sl->master, wrbuf, 3);

		w1_read_block(sl->master, buf, count);

		if (w1_reset_select_slave(sl))

			return -1;

		w1_write_block(sl->master, wrbuf, 3);

		w1_read_block(sl->master, cmp, count);

		if (!memcmp(cmp, buf, count))

			return 0;

	} while (--tries);

	dev_err(&sl->dev, "proof reading failed %d times\n",

			W1_F2D_READ_RETRIES);

	return -1;

}

static ssize_t w1_f2d_read_bin(struct kobject *kobj,

			       struct bin_attribute *bin_attr,

			       char *buf, loff_t off, size_t count)

{

	struct w1_slave *sl = kobj_to_w1_slave(kobj);

	int todo = count;

	count = w1_f2d_fix_count(off, count, W1_F2D_EEPROM_SIZE);

	if (count == 0)

		return 0;

	mutex_lock(&sl->master->mutex);

	/* read directly from the EEPROM in chunks of W1_F2D_READ_MAXLEN */

	while (todo > 0) {

		int block_read;

		if (todo >= W1_F2D_READ_MAXLEN)

			block_read = W1_F2D_READ_MAXLEN;

		else

			block_read = todo;

		if (w1_f2d_readblock(sl, off, block_read, buf) < 0)

			count = -EIO;

		todo -= W1_F2D_READ_MAXLEN;

		buf += W1_F2D_READ_MAXLEN;

		off += W1_F2D_READ_MAXLEN;

	}

	mutex_unlock(&sl->master->mutex);

	return count;

}

/*

 * Writes to the scratchpad and reads it back for verification.

 * Then copies the scratchpad to EEPROM.

 * The data must be aligned at W1_F2D_SCRATCH_SIZE bytes and

 * must be W1_F2D_SCRATCH_SIZE bytes long.

 * The master must be locked.

 *

 * @param sl	The slave structure

 * @param addr	Address for the write

 * @param len   length must be <= (W1_F2D_PAGE_SIZE - (addr & W1_F2D_PAGE_MASK))

 * @param data	The data to write

 * @return	0=Success -1=failure

 */

static int w1_f2d_write(struct w1_slave *sl, int addr, int len, const u8 *data)

{

	int tries = W1_F2D_READ_RETRIES;

	u8 wrbuf[4];

	u8 rdbuf[W1_F2D_SCRATCH_SIZE + 3];

	u8 es = (addr + len - 1) % W1_F2D_SCRATCH_SIZE;

retry:

	/* Write the data to the scratchpad */

	if (w1_reset_select_slave(sl))

		return -1;

	wrbuf[0] = W1_F2D_WRITE_SCRATCH;

	wrbuf[1] = addr & 0xff;

	wrbuf[2] = addr >> 8;

	w1_write_block(sl->master, wrbuf, 3);

	w1_write_block(sl->master, data, len);

	/* Read the scratchpad and verify */

	if (w1_reset_select_slave(sl))

		return -1;

	w1_write_8(sl->master, W1_F2D_READ_SCRATCH);

	w1_read_block(sl->master, rdbuf, len + 3);

	/* Compare what was read against the data written */

	if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||

	    (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0)) {

		if (--tries)

			goto retry;

		dev_err(&sl->dev,

			"could not write to eeprom, scratchpad compare failed %d times\n",

			W1_F2D_READ_RETRIES);

		return -1;

	}

	/* Copy the scratchpad to EEPROM */

	if (w1_reset_select_slave(sl))

		return -1;

	wrbuf[0] = W1_F2D_COPY_SCRATCH;

	wrbuf[3] = es;

	w1_write_block(sl->master, wrbuf, 4);

	/* Sleep for tprog ms to wait for the write to complete */

	msleep(W1_F2D_TPROG_MS);

	/* Reset the bus to wake up the EEPROM  */

	w1_reset_bus(sl->master);

	return 0;

}

static ssize_t w1_f2d_write_bin(struct kobject *kobj,

				struct bin_attribute *bin_attr,

				char *buf, loff_t off, size_t count)

{

	struct w1_slave *sl = kobj_to_w1_slave(kobj);

	int addr, len;

	int copy;

	count = w1_f2d_fix_count(off, count, W1_F2D_EEPROM_SIZE);

	if (count == 0)

		return 0;

	mutex_lock(&sl->master->mutex);

	/* Can only write data in blocks of the size of the scratchpad */

	addr = off;

	len = count;

	while (len > 0) {

		/* if len too short or addr not aligned */

		if (len < W1_F2D_SCRATCH_SIZE || addr & W1_F2D_SCRATCH_MASK) {

			char tmp[W1_F2D_SCRATCH_SIZE];

			/* read the block and update the parts to be written */

			if (w1_f2d_readblock(sl, addr & ~W1_F2D_SCRATCH_MASK,

					W1_F2D_SCRATCH_SIZE, tmp)) {

				count = -EIO;

				goto out_up;

			}

			/* copy at most to the boundary of the PAGE or len */

			copy = W1_F2D_SCRATCH_SIZE -

				(addr & W1_F2D_SCRATCH_MASK);

			if (copy > len)

				copy = len;

			memcpy(&tmp[addr & W1_F2D_SCRATCH_MASK], buf, copy);

			if (w1_f2d_write(sl, addr & ~W1_F2D_SCRATCH_MASK,

					W1_F2D_SCRATCH_SIZE, tmp) < 0) {

				count = -EIO;

				goto out_up;

			}

		} else {

			copy = W1_F2D_SCRATCH_SIZE;

			if (w1_f2d_write(sl, addr, copy, buf) < 0) {

				count = -EIO;

				goto out_up;

			}

		}

		buf += copy;

		addr += copy;

		len -= copy;

	}

out_up:

	mutex_unlock(&sl->master->mutex);

	return count;

}

static struct bin_attribute w1_f2d_bin_attr = {

	.attr = {

		.name = "eeprom",

		.mode = S_IRUGO | S_IWUSR,

	},

	.size = W1_F2D_EEPROM_SIZE,

	.read = w1_f2d_read_bin,

	.write = w1_f2d_write_bin,

};

static int w1_f2d_add_slave(struct w1_slave *sl)

{

	return sysfs_create_bin_file(&sl->dev.kobj, &w1_f2d_bin_attr);

}

static void w1_f2d_remove_slave(struct w1_slave *sl)

{

	sysfs_remove_bin_file(&sl->dev.kobj, &w1_f2d_bin_attr);

}

static struct w1_family_ops w1_f2d_fops = {

	.add_slave      = w1_f2d_add_slave,

	.remove_slave   = w1_f2d_remove_slave,

};

static struct w1_family w1_family_2d = {

	.fid = W1_EEPROM_DS2431,

	.fops = &w1_f2d_fops,

};

static int __init w1_f2d_init(void)

{

	return w1_register_family(&w1_family_2d);

}

static void __exit w1_f2d_fini(void)

{

	w1_unregister_family(&w1_family_2d);

}

module_init(w1_f2d_init);

module_exit(w1_f2d_fini);

MODULE_LICENSE("GPL");

MODULE_AUTHOR("Bernhard Weirich <bernhard.weirich@riedel.net>");

MODULE_DESCRIPTION("w1 family 2d driver for DS2431, 1kb EEPROM");

#define W1_THERM_DS1822  	0x22

#define W1_EEPROM_DS2433  	0x23

#define W1_THERM_DS18B20 	0x28

#define W1_EEPROM_DS2431	0x2D

#define W1_FAMILY_DS2760	0x30

#define MAXNAMELEN		32