1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * w1_ds2431.c - w1 family 2d (DS2431) driver 4 * 5 * Copyright (c) 2008 Bernhard Weirich <bernhard.weirich@riedel.net> 6 * 7 * Heavily inspired by w1_DS2433 driver from Ben Gardner <bgardner@wabtec.com> 8 */ 9 10 #include <linux/kernel.h> 11 #include <linux/module.h> 12 #include <linux/moduleparam.h> 13 #include <linux/device.h> 14 #include <linux/types.h> 15 #include <linux/delay.h> 16 17 #include <linux/w1.h> 18 19 #define W1_EEPROM_DS2431 0x2D 20 21 #define W1_F2D_EEPROM_SIZE 128 22 #define W1_F2D_PAGE_COUNT 4 23 #define W1_F2D_PAGE_BITS 5 24 #define W1_F2D_PAGE_SIZE (1<<W1_F2D_PAGE_BITS) 25 #define W1_F2D_PAGE_MASK 0x1F 26 27 #define W1_F2D_SCRATCH_BITS 3 28 #define W1_F2D_SCRATCH_SIZE (1<<W1_F2D_SCRATCH_BITS) 29 #define W1_F2D_SCRATCH_MASK (W1_F2D_SCRATCH_SIZE-1) 30 31 #define W1_F2D_READ_EEPROM 0xF0 32 #define W1_F2D_WRITE_SCRATCH 0x0F 33 #define W1_F2D_READ_SCRATCH 0xAA 34 #define W1_F2D_COPY_SCRATCH 0x55 35 36 37 #define W1_F2D_TPROG_MS 11 38 39 #define W1_F2D_READ_RETRIES 10 40 #define W1_F2D_READ_MAXLEN 8 41 42 /* 43 * Check the file size bounds and adjusts count as needed. 44 * This would not be needed if the file size didn't reset to 0 after a write. 45 */ 46 static inline size_t w1_f2d_fix_count(loff_t off, size_t count, size_t size) 47 { 48 if (off > size) 49 return 0; 50 51 if ((off + count) > size) 52 return size - off; 53 54 return count; 55 } 56 57 /* 58 * Read a block from W1 ROM two times and compares the results. 59 * If they are equal they are returned, otherwise the read 60 * is repeated W1_F2D_READ_RETRIES times. 61 * 62 * count must not exceed W1_F2D_READ_MAXLEN. 63 */ 64 static int w1_f2d_readblock(struct w1_slave *sl, int off, int count, char *buf) 65 { 66 u8 wrbuf[3]; 67 u8 cmp[W1_F2D_READ_MAXLEN]; 68 int tries = W1_F2D_READ_RETRIES; 69 70 do { 71 wrbuf[0] = W1_F2D_READ_EEPROM; 72 wrbuf[1] = off & 0xff; 73 wrbuf[2] = off >> 8; 74 75 if (w1_reset_select_slave(sl)) 76 return -1; 77 78 w1_write_block(sl->master, wrbuf, 3); 79 w1_read_block(sl->master, buf, count); 80 81 if (w1_reset_select_slave(sl)) 82 return -1; 83 84 w1_write_block(sl->master, wrbuf, 3); 85 w1_read_block(sl->master, cmp, count); 86 87 if (!memcmp(cmp, buf, count)) 88 return 0; 89 } while (--tries); 90 91 dev_err(&sl->dev, "proof reading failed %d times\n", 92 W1_F2D_READ_RETRIES); 93 94 return -1; 95 } 96 97 static ssize_t eeprom_read(struct file *filp, struct kobject *kobj, 98 struct bin_attribute *bin_attr, char *buf, 99 loff_t off, size_t count) 100 { 101 struct w1_slave *sl = kobj_to_w1_slave(kobj); 102 int todo = count; 103 104 count = w1_f2d_fix_count(off, count, W1_F2D_EEPROM_SIZE); 105 if (count == 0) 106 return 0; 107 108 mutex_lock(&sl->master->bus_mutex); 109 110 /* read directly from the EEPROM in chunks of W1_F2D_READ_MAXLEN */ 111 while (todo > 0) { 112 int block_read; 113 114 if (todo >= W1_F2D_READ_MAXLEN) 115 block_read = W1_F2D_READ_MAXLEN; 116 else 117 block_read = todo; 118 119 if (w1_f2d_readblock(sl, off, block_read, buf) < 0) 120 count = -EIO; 121 122 todo -= W1_F2D_READ_MAXLEN; 123 buf += W1_F2D_READ_MAXLEN; 124 off += W1_F2D_READ_MAXLEN; 125 } 126 127 mutex_unlock(&sl->master->bus_mutex); 128 129 return count; 130 } 131 132 /* 133 * Writes to the scratchpad and reads it back for verification. 134 * Then copies the scratchpad to EEPROM. 135 * The data must be aligned at W1_F2D_SCRATCH_SIZE bytes and 136 * must be W1_F2D_SCRATCH_SIZE bytes long. 137 * The master must be locked. 138 * 139 * @param sl The slave structure 140 * @param addr Address for the write 141 * @param len length must be <= (W1_F2D_PAGE_SIZE - (addr & W1_F2D_PAGE_MASK)) 142 * @param data The data to write 143 * @return 0=Success -1=failure 144 */ 145 static int w1_f2d_write(struct w1_slave *sl, int addr, int len, const u8 *data) 146 { 147 int tries = W1_F2D_READ_RETRIES; 148 u8 wrbuf[4]; 149 u8 rdbuf[W1_F2D_SCRATCH_SIZE + 3]; 150 u8 es = (addr + len - 1) % W1_F2D_SCRATCH_SIZE; 151 152 retry: 153 154 /* Write the data to the scratchpad */ 155 if (w1_reset_select_slave(sl)) 156 return -1; 157 158 wrbuf[0] = W1_F2D_WRITE_SCRATCH; 159 wrbuf[1] = addr & 0xff; 160 wrbuf[2] = addr >> 8; 161 162 w1_write_block(sl->master, wrbuf, 3); 163 w1_write_block(sl->master, data, len); 164 165 /* Read the scratchpad and verify */ 166 if (w1_reset_select_slave(sl)) 167 return -1; 168 169 w1_write_8(sl->master, W1_F2D_READ_SCRATCH); 170 w1_read_block(sl->master, rdbuf, len + 3); 171 172 /* Compare what was read against the data written */ 173 if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) || 174 (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0)) { 175 176 if (--tries) 177 goto retry; 178 179 dev_err(&sl->dev, 180 "could not write to eeprom, scratchpad compare failed %d times\n", 181 W1_F2D_READ_RETRIES); 182 183 return -1; 184 } 185 186 /* Copy the scratchpad to EEPROM */ 187 if (w1_reset_select_slave(sl)) 188 return -1; 189 190 wrbuf[0] = W1_F2D_COPY_SCRATCH; 191 wrbuf[3] = es; 192 w1_write_block(sl->master, wrbuf, 4); 193 194 /* Sleep for tprog ms to wait for the write to complete */ 195 msleep(W1_F2D_TPROG_MS); 196 197 /* Reset the bus to wake up the EEPROM */ 198 w1_reset_bus(sl->master); 199 200 return 0; 201 } 202 203 static ssize_t eeprom_write(struct file *filp, struct kobject *kobj, 204 struct bin_attribute *bin_attr, char *buf, 205 loff_t off, size_t count) 206 { 207 struct w1_slave *sl = kobj_to_w1_slave(kobj); 208 int addr, len; 209 int copy; 210 211 count = w1_f2d_fix_count(off, count, W1_F2D_EEPROM_SIZE); 212 if (count == 0) 213 return 0; 214 215 mutex_lock(&sl->master->bus_mutex); 216 217 /* Can only write data in blocks of the size of the scratchpad */ 218 addr = off; 219 len = count; 220 while (len > 0) { 221 222 /* if len too short or addr not aligned */ 223 if (len < W1_F2D_SCRATCH_SIZE || addr & W1_F2D_SCRATCH_MASK) { 224 char tmp[W1_F2D_SCRATCH_SIZE]; 225 226 /* read the block and update the parts to be written */ 227 if (w1_f2d_readblock(sl, addr & ~W1_F2D_SCRATCH_MASK, 228 W1_F2D_SCRATCH_SIZE, tmp)) { 229 count = -EIO; 230 goto out_up; 231 } 232 233 /* copy at most to the boundary of the PAGE or len */ 234 copy = W1_F2D_SCRATCH_SIZE - 235 (addr & W1_F2D_SCRATCH_MASK); 236 237 if (copy > len) 238 copy = len; 239 240 memcpy(&tmp[addr & W1_F2D_SCRATCH_MASK], buf, copy); 241 if (w1_f2d_write(sl, addr & ~W1_F2D_SCRATCH_MASK, 242 W1_F2D_SCRATCH_SIZE, tmp) < 0) { 243 count = -EIO; 244 goto out_up; 245 } 246 } else { 247 248 copy = W1_F2D_SCRATCH_SIZE; 249 if (w1_f2d_write(sl, addr, copy, buf) < 0) { 250 count = -EIO; 251 goto out_up; 252 } 253 } 254 buf += copy; 255 addr += copy; 256 len -= copy; 257 } 258 259 out_up: 260 mutex_unlock(&sl->master->bus_mutex); 261 262 return count; 263 } 264 265 static BIN_ATTR_RW(eeprom, W1_F2D_EEPROM_SIZE); 266 267 static struct bin_attribute *w1_f2d_bin_attrs[] = { 268 &bin_attr_eeprom, 269 NULL, 270 }; 271 272 static const struct attribute_group w1_f2d_group = { 273 .bin_attrs = w1_f2d_bin_attrs, 274 }; 275 276 static const struct attribute_group *w1_f2d_groups[] = { 277 &w1_f2d_group, 278 NULL, 279 }; 280 281 static struct w1_family_ops w1_f2d_fops = { 282 .groups = w1_f2d_groups, 283 }; 284 285 static struct w1_family w1_family_2d = { 286 .fid = W1_EEPROM_DS2431, 287 .fops = &w1_f2d_fops, 288 }; 289 module_w1_family(w1_family_2d); 290 291 MODULE_AUTHOR("Bernhard Weirich <bernhard.weirich@riedel.net>"); 292 MODULE_DESCRIPTION("w1 family 2d driver for DS2431, 1kb EEPROM"); 293 MODULE_LICENSE("GPL"); 294 MODULE_ALIAS("w1-family-" __stringify(W1_EEPROM_DS2431)); 295