/*
* w1_ds2423.c
*
* Copyright (c) 2010 Mika Laitio <lamikr@pilppa.org>
*
* This driver will read and write the value of 4 counters to w1_slave file in
* sys filesystem.
* Inspired by the w1_therm and w1_ds2431 drivers.
*
* This program is free software; you can redistribute it and/or modify
* it under the therms 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#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 <linux/crc16.h>
#include "../w1.h"
#include "../w1_int.h"
#include "../w1_family.h"
#define CRC16_VALID 0xb001
#define CRC16_INIT 0
#define COUNTER_COUNT 4
#define READ_BYTE_COUNT 42
static ssize_t w1_counter_read(struct device *device,
struct device_attribute *attr, char *buf);
static struct device_attribute w1_counter_attr =
__ATTR(w1_slave, S_IRUGO, w1_counter_read, NULL);
static ssize_t w1_counter_read(struct device *device,
struct device_attribute *attr, char *out_buf)
{
struct w1_slave *sl = dev_to_w1_slave(device);
struct w1_master *dev = sl->master;
u8 rbuf[COUNTER_COUNT * READ_BYTE_COUNT];
u8 wrbuf[3];
int rom_addr;
int read_byte_count;
int result;
ssize_t c;
int ii;
int p;
int crc;
c = PAGE_SIZE;
rom_addr = (12 << 5) + 31;
wrbuf[0] = 0xA5;
wrbuf[1] = rom_addr & 0xFF;
wrbuf[2] = rom_addr >> 8;
mutex_lock(&dev->mutex);
if (!w1_reset_select_slave(sl)) {
w1_write_block(dev, wrbuf, 3);
read_byte_count = 0;
for (p = 0; p < 4; p++) {
/*
* 1 byte for first bytes in ram page read
* 4 bytes for counter
* 4 bytes for zero bits
* 2 bytes for crc
* 31 remaining bytes from the ram page
*/
read_byte_count += w1_read_block(dev,
rbuf + (p * READ_BYTE_COUNT), READ_BYTE_COUNT);
for (ii = 0; ii < READ_BYTE_COUNT; ++ii)
c -= snprintf(out_buf + PAGE_SIZE - c,
c, "%02x ",
rbuf[(p * READ_BYTE_COUNT) + ii]);
if (read_byte_count != (p + 1) * READ_BYTE_COUNT) {
dev_warn(device,
"w1_counter_read() returned %u bytes "
"instead of %d bytes wanted.\n",
read_byte_count,
READ_BYTE_COUNT);
c -= snprintf(out_buf + PAGE_SIZE - c,
c, "crc=NO\n");
} else {
if (p == 0) {
crc = crc16(CRC16_INIT, wrbuf, 3);
crc = crc16(crc, rbuf, 11);
} else {
/*
* DS2423 calculates crc from all bytes
* read after the previous crc bytes.
*/
crc = crc16(CRC16_INIT,
(rbuf + 11) +
((p - 1) * READ_BYTE_COUNT),
READ_BYTE_COUNT);
}
if (crc == CRC16_VALID) {
result = 0;
for (ii = 4; ii > 0; ii--) {
result <<= 8;
result |= rbuf[(p *
READ_BYTE_COUNT) + ii];
}
c -= snprintf(out_buf + PAGE_SIZE - c,
c, "crc=YES c=%d\n", result);
} else {
c -= snprintf(out_buf + PAGE_SIZE - c,
c, "crc=NO\n");
}
}
}
} else {
c -= snprintf(out_buf + PAGE_SIZE - c, c, "Connection error");
}
mutex_unlock(&dev->mutex);
return PAGE_SIZE - c;
}
static int w1_f1d_add_slave(struct w1_slave *sl)
{
return device_create_file(&sl->dev, &w1_counter_attr);
}
static void w1_f1d_remove_slave(struct w1_slave *sl)
{
device_remove_file(&sl->dev, &w1_counter_attr);
}
static struct w1_family_ops w1_f1d_fops = {
.add_slave = w1_f1d_add_slave,
.remove_slave = w1_f1d_remove_slave,
};
static struct w1_family w1_family_1d = {
.fid = W1_COUNTER_DS2423,
.fops = &w1_f1d_fops,
};
static int __init w1_f1d_init(void)
{
return w1_register_family(&w1_family_1d);
}
static void __exit w1_f1d_exit(void)
{
w1_unregister_family(&w1_family_1d);
}
module_init(w1_f1d_init);
module_exit(w1_f1d_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Mika Laitio <lamikr@pilppa.org>");
MODULE_DESCRIPTION("w1 family 1d driver for DS2423, 4 counters and 4kb ram");
