1 /* 2 * w1_ds2423.c 3 * 4 * Copyright (c) 2010 Mika Laitio <lamikr@pilppa.org> 5 * 6 * This driver will read and write the value of 4 counters to w1_slave file in 7 * sys filesystem. 8 * Inspired by the w1_therm and w1_ds2431 drivers. 9 * 10 * This program is free software; you can redistribute it and/or modify 11 * it under the therms of the GNU General Public License as published by 12 * the Free Software Foundation; either version 2 of the License, or 13 * (at your option) any later version. 14 * 15 * This program is distributed in the hope that it will be useful, 16 * but WITHOUT ANY WARRANTY; without even the implied warranty of 17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 18 * GNU General Public License for more details. 19 * 20 * You should have received a copy of the GNU General Public License 21 * along with this program; if not, write to the Free Software 22 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 23 */ 24 25 #include <linux/kernel.h> 26 #include <linux/module.h> 27 #include <linux/moduleparam.h> 28 #include <linux/device.h> 29 #include <linux/types.h> 30 #include <linux/delay.h> 31 #include <linux/crc16.h> 32 33 #include <linux/w1.h> 34 35 #define W1_COUNTER_DS2423 0x1D 36 37 #define CRC16_VALID 0xb001 38 #define CRC16_INIT 0 39 40 #define COUNTER_COUNT 4 41 #define READ_BYTE_COUNT 42 42 43 static ssize_t w1_slave_show(struct device *device, 44 struct device_attribute *attr, char *out_buf) 45 { 46 struct w1_slave *sl = dev_to_w1_slave(device); 47 struct w1_master *dev = sl->master; 48 u8 rbuf[COUNTER_COUNT * READ_BYTE_COUNT]; 49 u8 wrbuf[3]; 50 int rom_addr; 51 int read_byte_count; 52 int result; 53 ssize_t c; 54 int ii; 55 int p; 56 int crc; 57 58 c = PAGE_SIZE; 59 rom_addr = (12 << 5) + 31; 60 wrbuf[0] = 0xA5; 61 wrbuf[1] = rom_addr & 0xFF; 62 wrbuf[2] = rom_addr >> 8; 63 mutex_lock(&dev->bus_mutex); 64 if (!w1_reset_select_slave(sl)) { 65 w1_write_block(dev, wrbuf, 3); 66 read_byte_count = 0; 67 for (p = 0; p < 4; p++) { 68 /* 69 * 1 byte for first bytes in ram page read 70 * 4 bytes for counter 71 * 4 bytes for zero bits 72 * 2 bytes for crc 73 * 31 remaining bytes from the ram page 74 */ 75 read_byte_count += w1_read_block(dev, 76 rbuf + (p * READ_BYTE_COUNT), READ_BYTE_COUNT); 77 for (ii = 0; ii < READ_BYTE_COUNT; ++ii) 78 c -= snprintf(out_buf + PAGE_SIZE - c, 79 c, "%02x ", 80 rbuf[(p * READ_BYTE_COUNT) + ii]); 81 if (read_byte_count != (p + 1) * READ_BYTE_COUNT) { 82 dev_warn(device, 83 "w1_counter_read() returned %u bytes " 84 "instead of %d bytes wanted.\n", 85 read_byte_count, 86 READ_BYTE_COUNT); 87 c -= snprintf(out_buf + PAGE_SIZE - c, 88 c, "crc=NO\n"); 89 } else { 90 if (p == 0) { 91 crc = crc16(CRC16_INIT, wrbuf, 3); 92 crc = crc16(crc, rbuf, 11); 93 } else { 94 /* 95 * DS2423 calculates crc from all bytes 96 * read after the previous crc bytes. 97 */ 98 crc = crc16(CRC16_INIT, 99 (rbuf + 11) + 100 ((p - 1) * READ_BYTE_COUNT), 101 READ_BYTE_COUNT); 102 } 103 if (crc == CRC16_VALID) { 104 result = 0; 105 for (ii = 4; ii > 0; ii--) { 106 result <<= 8; 107 result |= rbuf[(p * 108 READ_BYTE_COUNT) + ii]; 109 } 110 c -= snprintf(out_buf + PAGE_SIZE - c, 111 c, "crc=YES c=%d\n", result); 112 } else { 113 c -= snprintf(out_buf + PAGE_SIZE - c, 114 c, "crc=NO\n"); 115 } 116 } 117 } 118 } else { 119 c -= snprintf(out_buf + PAGE_SIZE - c, c, "Connection error"); 120 } 121 mutex_unlock(&dev->bus_mutex); 122 return PAGE_SIZE - c; 123 } 124 125 static DEVICE_ATTR_RO(w1_slave); 126 127 static struct attribute *w1_f1d_attrs[] = { 128 &dev_attr_w1_slave.attr, 129 NULL, 130 }; 131 ATTRIBUTE_GROUPS(w1_f1d); 132 133 static struct w1_family_ops w1_f1d_fops = { 134 .groups = w1_f1d_groups, 135 }; 136 137 static struct w1_family w1_family_1d = { 138 .fid = W1_COUNTER_DS2423, 139 .fops = &w1_f1d_fops, 140 }; 141 module_w1_family(w1_family_1d); 142 143 MODULE_AUTHOR("Mika Laitio <lamikr@pilppa.org>"); 144 MODULE_DESCRIPTION("w1 family 1d driver for DS2423, 4 counters and 4kb ram"); 145 MODULE_LICENSE("GPL"); 146 MODULE_ALIAS("w1-family-" __stringify(W1_COUNTER_DS2423)); 147