147 lines
3.8 KiB
C
147 lines
3.8 KiB
C
/*
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* w1_ds2423.c
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*
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* Copyright (c) 2010 Mika Laitio <lamikr@pilppa.org>
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*
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* This driver will read and write the value of 4 counters to w1_slave file in
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* sys filesystem.
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* Inspired by the w1_therm and w1_ds2431 drivers.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the therms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/device.h>
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#include <linux/types.h>
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#include <linux/delay.h>
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#include <linux/crc16.h>
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#include <linux/w1.h>
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#define W1_COUNTER_DS2423 0x1D
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#define CRC16_VALID 0xb001
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#define CRC16_INIT 0
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#define COUNTER_COUNT 4
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#define READ_BYTE_COUNT 42
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static ssize_t w1_slave_show(struct device *device,
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struct device_attribute *attr, char *out_buf)
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{
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struct w1_slave *sl = dev_to_w1_slave(device);
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struct w1_master *dev = sl->master;
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u8 rbuf[COUNTER_COUNT * READ_BYTE_COUNT];
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u8 wrbuf[3];
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int rom_addr;
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int read_byte_count;
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int result;
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ssize_t c;
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int ii;
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int p;
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int crc;
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c = PAGE_SIZE;
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rom_addr = (12 << 5) + 31;
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wrbuf[0] = 0xA5;
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wrbuf[1] = rom_addr & 0xFF;
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wrbuf[2] = rom_addr >> 8;
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mutex_lock(&dev->bus_mutex);
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if (!w1_reset_select_slave(sl)) {
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w1_write_block(dev, wrbuf, 3);
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read_byte_count = 0;
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for (p = 0; p < 4; p++) {
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/*
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* 1 byte for first bytes in ram page read
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* 4 bytes for counter
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* 4 bytes for zero bits
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* 2 bytes for crc
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* 31 remaining bytes from the ram page
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*/
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read_byte_count += w1_read_block(dev,
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rbuf + (p * READ_BYTE_COUNT), READ_BYTE_COUNT);
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for (ii = 0; ii < READ_BYTE_COUNT; ++ii)
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c -= snprintf(out_buf + PAGE_SIZE - c,
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c, "%02x ",
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rbuf[(p * READ_BYTE_COUNT) + ii]);
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if (read_byte_count != (p + 1) * READ_BYTE_COUNT) {
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dev_warn(device,
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"w1_counter_read() returned %u bytes "
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"instead of %d bytes wanted.\n",
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read_byte_count,
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READ_BYTE_COUNT);
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c -= snprintf(out_buf + PAGE_SIZE - c,
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c, "crc=NO\n");
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} else {
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if (p == 0) {
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crc = crc16(CRC16_INIT, wrbuf, 3);
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crc = crc16(crc, rbuf, 11);
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} else {
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/*
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* DS2423 calculates crc from all bytes
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* read after the previous crc bytes.
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*/
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crc = crc16(CRC16_INIT,
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(rbuf + 11) +
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((p - 1) * READ_BYTE_COUNT),
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READ_BYTE_COUNT);
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}
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if (crc == CRC16_VALID) {
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result = 0;
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for (ii = 4; ii > 0; ii--) {
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result <<= 8;
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result |= rbuf[(p *
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READ_BYTE_COUNT) + ii];
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}
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c -= snprintf(out_buf + PAGE_SIZE - c,
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c, "crc=YES c=%d\n", result);
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} else {
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c -= snprintf(out_buf + PAGE_SIZE - c,
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c, "crc=NO\n");
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}
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}
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}
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} else {
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c -= snprintf(out_buf + PAGE_SIZE - c, c, "Connection error");
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}
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mutex_unlock(&dev->bus_mutex);
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return PAGE_SIZE - c;
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}
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static DEVICE_ATTR_RO(w1_slave);
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static struct attribute *w1_f1d_attrs[] = {
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&dev_attr_w1_slave.attr,
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NULL,
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};
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ATTRIBUTE_GROUPS(w1_f1d);
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static struct w1_family_ops w1_f1d_fops = {
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.groups = w1_f1d_groups,
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};
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static struct w1_family w1_family_1d = {
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.fid = W1_COUNTER_DS2423,
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.fops = &w1_f1d_fops,
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};
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module_w1_family(w1_family_1d);
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MODULE_AUTHOR("Mika Laitio <lamikr@pilppa.org>");
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MODULE_DESCRIPTION("w1 family 1d driver for DS2423, 4 counters and 4kb ram");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("w1-family-" __stringify(W1_COUNTER_DS2423));
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