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