1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-or-later
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * w1_ds2423.c
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright (c) 2010 Mika Laitio <lamikr@pilppa.org>
6*4882a593Smuzhiyun *
7*4882a593Smuzhiyun * This driver will read and write the value of 4 counters to w1_slave file in
8*4882a593Smuzhiyun * sys filesystem.
9*4882a593Smuzhiyun * Inspired by the w1_therm and w1_ds2431 drivers.
10*4882a593Smuzhiyun */
11*4882a593Smuzhiyun
12*4882a593Smuzhiyun #include <linux/kernel.h>
13*4882a593Smuzhiyun #include <linux/module.h>
14*4882a593Smuzhiyun #include <linux/moduleparam.h>
15*4882a593Smuzhiyun #include <linux/device.h>
16*4882a593Smuzhiyun #include <linux/types.h>
17*4882a593Smuzhiyun #include <linux/delay.h>
18*4882a593Smuzhiyun #include <linux/crc16.h>
19*4882a593Smuzhiyun
20*4882a593Smuzhiyun #include <linux/w1.h>
21*4882a593Smuzhiyun
22*4882a593Smuzhiyun #define W1_COUNTER_DS2423 0x1D
23*4882a593Smuzhiyun
24*4882a593Smuzhiyun #define CRC16_VALID 0xb001
25*4882a593Smuzhiyun #define CRC16_INIT 0
26*4882a593Smuzhiyun
27*4882a593Smuzhiyun #define COUNTER_COUNT 4
28*4882a593Smuzhiyun #define READ_BYTE_COUNT 42
29*4882a593Smuzhiyun
w1_slave_show(struct device * device,struct device_attribute * attr,char * out_buf)30*4882a593Smuzhiyun static ssize_t w1_slave_show(struct device *device,
31*4882a593Smuzhiyun struct device_attribute *attr, char *out_buf)
32*4882a593Smuzhiyun {
33*4882a593Smuzhiyun struct w1_slave *sl = dev_to_w1_slave(device);
34*4882a593Smuzhiyun struct w1_master *dev = sl->master;
35*4882a593Smuzhiyun u8 rbuf[COUNTER_COUNT * READ_BYTE_COUNT];
36*4882a593Smuzhiyun u8 wrbuf[3];
37*4882a593Smuzhiyun int rom_addr;
38*4882a593Smuzhiyun int read_byte_count;
39*4882a593Smuzhiyun int result;
40*4882a593Smuzhiyun ssize_t c;
41*4882a593Smuzhiyun int ii;
42*4882a593Smuzhiyun int p;
43*4882a593Smuzhiyun int crc;
44*4882a593Smuzhiyun
45*4882a593Smuzhiyun c = PAGE_SIZE;
46*4882a593Smuzhiyun rom_addr = (12 << 5) + 31;
47*4882a593Smuzhiyun wrbuf[0] = 0xA5;
48*4882a593Smuzhiyun wrbuf[1] = rom_addr & 0xFF;
49*4882a593Smuzhiyun wrbuf[2] = rom_addr >> 8;
50*4882a593Smuzhiyun mutex_lock(&dev->bus_mutex);
51*4882a593Smuzhiyun if (!w1_reset_select_slave(sl)) {
52*4882a593Smuzhiyun w1_write_block(dev, wrbuf, 3);
53*4882a593Smuzhiyun read_byte_count = 0;
54*4882a593Smuzhiyun for (p = 0; p < 4; p++) {
55*4882a593Smuzhiyun /*
56*4882a593Smuzhiyun * 1 byte for first bytes in ram page read
57*4882a593Smuzhiyun * 4 bytes for counter
58*4882a593Smuzhiyun * 4 bytes for zero bits
59*4882a593Smuzhiyun * 2 bytes for crc
60*4882a593Smuzhiyun * 31 remaining bytes from the ram page
61*4882a593Smuzhiyun */
62*4882a593Smuzhiyun read_byte_count += w1_read_block(dev,
63*4882a593Smuzhiyun rbuf + (p * READ_BYTE_COUNT), READ_BYTE_COUNT);
64*4882a593Smuzhiyun for (ii = 0; ii < READ_BYTE_COUNT; ++ii)
65*4882a593Smuzhiyun c -= snprintf(out_buf + PAGE_SIZE - c,
66*4882a593Smuzhiyun c, "%02x ",
67*4882a593Smuzhiyun rbuf[(p * READ_BYTE_COUNT) + ii]);
68*4882a593Smuzhiyun if (read_byte_count != (p + 1) * READ_BYTE_COUNT) {
69*4882a593Smuzhiyun dev_warn(device,
70*4882a593Smuzhiyun "w1_counter_read() returned %u bytes "
71*4882a593Smuzhiyun "instead of %d bytes wanted.\n",
72*4882a593Smuzhiyun read_byte_count,
73*4882a593Smuzhiyun READ_BYTE_COUNT);
74*4882a593Smuzhiyun c -= snprintf(out_buf + PAGE_SIZE - c,
75*4882a593Smuzhiyun c, "crc=NO\n");
76*4882a593Smuzhiyun } else {
77*4882a593Smuzhiyun if (p == 0) {
78*4882a593Smuzhiyun crc = crc16(CRC16_INIT, wrbuf, 3);
79*4882a593Smuzhiyun crc = crc16(crc, rbuf, 11);
80*4882a593Smuzhiyun } else {
81*4882a593Smuzhiyun /*
82*4882a593Smuzhiyun * DS2423 calculates crc from all bytes
83*4882a593Smuzhiyun * read after the previous crc bytes.
84*4882a593Smuzhiyun */
85*4882a593Smuzhiyun crc = crc16(CRC16_INIT,
86*4882a593Smuzhiyun (rbuf + 11) +
87*4882a593Smuzhiyun ((p - 1) * READ_BYTE_COUNT),
88*4882a593Smuzhiyun READ_BYTE_COUNT);
89*4882a593Smuzhiyun }
90*4882a593Smuzhiyun if (crc == CRC16_VALID) {
91*4882a593Smuzhiyun result = 0;
92*4882a593Smuzhiyun for (ii = 4; ii > 0; ii--) {
93*4882a593Smuzhiyun result <<= 8;
94*4882a593Smuzhiyun result |= rbuf[(p *
95*4882a593Smuzhiyun READ_BYTE_COUNT) + ii];
96*4882a593Smuzhiyun }
97*4882a593Smuzhiyun c -= snprintf(out_buf + PAGE_SIZE - c,
98*4882a593Smuzhiyun c, "crc=YES c=%d\n", result);
99*4882a593Smuzhiyun } else {
100*4882a593Smuzhiyun c -= snprintf(out_buf + PAGE_SIZE - c,
101*4882a593Smuzhiyun c, "crc=NO\n");
102*4882a593Smuzhiyun }
103*4882a593Smuzhiyun }
104*4882a593Smuzhiyun }
105*4882a593Smuzhiyun } else {
106*4882a593Smuzhiyun c -= snprintf(out_buf + PAGE_SIZE - c, c, "Connection error");
107*4882a593Smuzhiyun }
108*4882a593Smuzhiyun mutex_unlock(&dev->bus_mutex);
109*4882a593Smuzhiyun return PAGE_SIZE - c;
110*4882a593Smuzhiyun }
111*4882a593Smuzhiyun
112*4882a593Smuzhiyun static DEVICE_ATTR_RO(w1_slave);
113*4882a593Smuzhiyun
114*4882a593Smuzhiyun static struct attribute *w1_f1d_attrs[] = {
115*4882a593Smuzhiyun &dev_attr_w1_slave.attr,
116*4882a593Smuzhiyun NULL,
117*4882a593Smuzhiyun };
118*4882a593Smuzhiyun ATTRIBUTE_GROUPS(w1_f1d);
119*4882a593Smuzhiyun
120*4882a593Smuzhiyun static const struct w1_family_ops w1_f1d_fops = {
121*4882a593Smuzhiyun .groups = w1_f1d_groups,
122*4882a593Smuzhiyun };
123*4882a593Smuzhiyun
124*4882a593Smuzhiyun static struct w1_family w1_family_1d = {
125*4882a593Smuzhiyun .fid = W1_COUNTER_DS2423,
126*4882a593Smuzhiyun .fops = &w1_f1d_fops,
127*4882a593Smuzhiyun };
128*4882a593Smuzhiyun module_w1_family(w1_family_1d);
129*4882a593Smuzhiyun
130*4882a593Smuzhiyun MODULE_AUTHOR("Mika Laitio <lamikr@pilppa.org>");
131*4882a593Smuzhiyun MODULE_DESCRIPTION("w1 family 1d driver for DS2423, 4 counters and 4kb ram");
132*4882a593Smuzhiyun MODULE_LICENSE("GPL");
133*4882a593Smuzhiyun MODULE_ALIAS("w1-family-" __stringify(W1_COUNTER_DS2423));
134