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(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(out_buf + PAGE_SIZE - c, 66 c, "%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(out_buf + PAGE_SIZE - c, 75 c, "crc=NO\n"); 76 } else { 77 if (p == 0) { 78 crc = crc16(CRC16_INIT, wrbuf, 3); 79 crc = crc16(crc, rbuf, 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 (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(out_buf + PAGE_SIZE - c, 98 c, "crc=YES c=%d\n", result); 99 } else { 100 c -= snprintf(out_buf + PAGE_SIZE - c, 101 c, "crc=NO\n"); 102 } 103 } 104 } 105 } else { 106 c -= snprintf(out_buf + PAGE_SIZE - c, c, "Connection error"); 107 } 108 mutex_unlock(&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