1 /* 2 * An SPI driver for the Philips PCF2123 RTC 3 * Copyright 2009 Cyber Switching, Inc. 4 * 5 * Author: Chris Verges <chrisv@cyberswitching.com> 6 * Maintainers: http://www.cyberswitching.com 7 * 8 * based on the RS5C348 driver in this same directory. 9 * 10 * Thanks to Christian Pellegrin <chripell@fsfe.org> for 11 * the sysfs contributions to this driver. 12 * 13 * This program is free software; you can redistribute it and/or modify 14 * it under the terms of the GNU General Public License version 2 as 15 * published by the Free Software Foundation. 16 * 17 * Please note that the CS is active high, so platform data 18 * should look something like: 19 * 20 * static struct spi_board_info ek_spi_devices[] = { 21 * ... 22 * { 23 * .modalias = "rtc-pcf2123", 24 * .chip_select = 1, 25 * .controller_data = (void *)AT91_PIN_PA10, 26 * .max_speed_hz = 1000 * 1000, 27 * .mode = SPI_CS_HIGH, 28 * .bus_num = 0, 29 * }, 30 * ... 31 *}; 32 * 33 */ 34 35 #include <linux/bcd.h> 36 #include <linux/delay.h> 37 #include <linux/device.h> 38 #include <linux/errno.h> 39 #include <linux/init.h> 40 #include <linux/kernel.h> 41 #include <linux/of.h> 42 #include <linux/string.h> 43 #include <linux/slab.h> 44 #include <linux/rtc.h> 45 #include <linux/spi/spi.h> 46 #include <linux/module.h> 47 #include <linux/sysfs.h> 48 49 /* REGISTERS */ 50 #define PCF2123_REG_CTRL1 (0x00) /* Control Register 1 */ 51 #define PCF2123_REG_CTRL2 (0x01) /* Control Register 2 */ 52 #define PCF2123_REG_SC (0x02) /* datetime */ 53 #define PCF2123_REG_MN (0x03) 54 #define PCF2123_REG_HR (0x04) 55 #define PCF2123_REG_DM (0x05) 56 #define PCF2123_REG_DW (0x06) 57 #define PCF2123_REG_MO (0x07) 58 #define PCF2123_REG_YR (0x08) 59 #define PCF2123_REG_ALRM_MN (0x09) /* Alarm Registers */ 60 #define PCF2123_REG_ALRM_HR (0x0a) 61 #define PCF2123_REG_ALRM_DM (0x0b) 62 #define PCF2123_REG_ALRM_DW (0x0c) 63 #define PCF2123_REG_OFFSET (0x0d) /* Clock Rate Offset Register */ 64 #define PCF2123_REG_TMR_CLKOUT (0x0e) /* Timer Registers */ 65 #define PCF2123_REG_CTDWN_TMR (0x0f) 66 67 /* PCF2123_REG_CTRL1 BITS */ 68 #define CTRL1_CLEAR (0) /* Clear */ 69 #define CTRL1_CORR_INT BIT(1) /* Correction irq enable */ 70 #define CTRL1_12_HOUR BIT(2) /* 12 hour time */ 71 #define CTRL1_SW_RESET (BIT(3) | BIT(4) | BIT(6)) /* Software reset */ 72 #define CTRL1_STOP BIT(5) /* Stop the clock */ 73 #define CTRL1_EXT_TEST BIT(7) /* External clock test mode */ 74 75 /* PCF2123_REG_CTRL2 BITS */ 76 #define CTRL2_TIE BIT(0) /* Countdown timer irq enable */ 77 #define CTRL2_AIE BIT(1) /* Alarm irq enable */ 78 #define CTRL2_TF BIT(2) /* Countdown timer flag */ 79 #define CTRL2_AF BIT(3) /* Alarm flag */ 80 #define CTRL2_TI_TP BIT(4) /* Irq pin generates pulse */ 81 #define CTRL2_MSF BIT(5) /* Minute or second irq flag */ 82 #define CTRL2_SI BIT(6) /* Second irq enable */ 83 #define CTRL2_MI BIT(7) /* Minute irq enable */ 84 85 /* PCF2123_REG_SC BITS */ 86 #define OSC_HAS_STOPPED BIT(7) /* Clock has been stopped */ 87 88 /* PCF2123_REG_ALRM_XX BITS */ 89 #define ALRM_ENABLE BIT(7) /* MN, HR, DM, or DW alarm enable */ 90 91 /* PCF2123_REG_TMR_CLKOUT BITS */ 92 #define CD_TMR_4096KHZ (0) /* 4096 KHz countdown timer */ 93 #define CD_TMR_64HZ (1) /* 64 Hz countdown timer */ 94 #define CD_TMR_1HZ (2) /* 1 Hz countdown timer */ 95 #define CD_TMR_60th_HZ (3) /* 60th Hz countdown timer */ 96 #define CD_TMR_TE BIT(3) /* Countdown timer enable */ 97 98 /* PCF2123_REG_OFFSET BITS */ 99 #define OFFSET_SIGN_BIT 6 /* 2's complement sign bit */ 100 #define OFFSET_COARSE BIT(7) /* Coarse mode offset */ 101 #define OFFSET_STEP (2170) /* Offset step in parts per billion */ 102 103 /* READ/WRITE ADDRESS BITS */ 104 #define PCF2123_WRITE BIT(4) 105 #define PCF2123_READ (BIT(4) | BIT(7)) 106 107 108 static struct spi_driver pcf2123_driver; 109 110 struct pcf2123_sysfs_reg { 111 struct device_attribute attr; 112 char name[2]; 113 }; 114 115 struct pcf2123_plat_data { 116 struct rtc_device *rtc; 117 struct pcf2123_sysfs_reg regs[16]; 118 }; 119 120 /* 121 * Causes a 30 nanosecond delay to ensure that the PCF2123 chip select 122 * is released properly after an SPI write. This function should be 123 * called after EVERY read/write call over SPI. 124 */ 125 static inline void pcf2123_delay_trec(void) 126 { 127 ndelay(30); 128 } 129 130 static int pcf2123_read(struct device *dev, u8 reg, u8 *rxbuf, size_t size) 131 { 132 struct spi_device *spi = to_spi_device(dev); 133 int ret; 134 135 reg |= PCF2123_READ; 136 ret = spi_write_then_read(spi, ®, 1, rxbuf, size); 137 pcf2123_delay_trec(); 138 139 return ret; 140 } 141 142 static int pcf2123_write(struct device *dev, u8 *txbuf, size_t size) 143 { 144 struct spi_device *spi = to_spi_device(dev); 145 int ret; 146 147 txbuf[0] |= PCF2123_WRITE; 148 ret = spi_write(spi, txbuf, size); 149 pcf2123_delay_trec(); 150 151 return ret; 152 } 153 154 static int pcf2123_write_reg(struct device *dev, u8 reg, u8 val) 155 { 156 u8 txbuf[2]; 157 158 txbuf[0] = reg; 159 txbuf[1] = val; 160 return pcf2123_write(dev, txbuf, sizeof(txbuf)); 161 } 162 163 static ssize_t pcf2123_show(struct device *dev, struct device_attribute *attr, 164 char *buffer) 165 { 166 struct pcf2123_sysfs_reg *r; 167 u8 rxbuf[1]; 168 unsigned long reg; 169 int ret; 170 171 r = container_of(attr, struct pcf2123_sysfs_reg, attr); 172 173 ret = kstrtoul(r->name, 16, ®); 174 if (ret) 175 return ret; 176 177 ret = pcf2123_read(dev, reg, rxbuf, 1); 178 if (ret < 0) 179 return -EIO; 180 181 return sprintf(buffer, "0x%x\n", rxbuf[0]); 182 } 183 184 static ssize_t pcf2123_store(struct device *dev, struct device_attribute *attr, 185 const char *buffer, size_t count) 186 { 187 struct pcf2123_sysfs_reg *r; 188 unsigned long reg; 189 unsigned long val; 190 191 int ret; 192 193 r = container_of(attr, struct pcf2123_sysfs_reg, attr); 194 195 ret = kstrtoul(r->name, 16, ®); 196 if (ret) 197 return ret; 198 199 ret = kstrtoul(buffer, 10, &val); 200 if (ret) 201 return ret; 202 203 ret = pcf2123_write_reg(dev, reg, val); 204 if (ret < 0) 205 return -EIO; 206 return count; 207 } 208 209 static int pcf2123_read_offset(struct device *dev, long *offset) 210 { 211 int ret; 212 s8 reg; 213 214 ret = pcf2123_read(dev, PCF2123_REG_OFFSET, ®, 1); 215 if (ret < 0) 216 return ret; 217 218 if (reg & OFFSET_COARSE) 219 reg <<= 1; /* multiply by 2 and sign extend */ 220 else 221 reg = sign_extend32(reg, OFFSET_SIGN_BIT); 222 223 *offset = ((long)reg) * OFFSET_STEP; 224 225 return 0; 226 } 227 228 /* 229 * The offset register is a 7 bit signed value with a coarse bit in bit 7. 230 * The main difference between the two is normal offset adjusts the first 231 * second of n minutes every other hour, with 61, 62 and 63 being shoved 232 * into the 60th minute. 233 * The coarse adjustment does the same, but every hour. 234 * the two overlap, with every even normal offset value corresponding 235 * to a coarse offset. Based on this algorithm, it seems that despite the 236 * name, coarse offset is a better fit for overlapping values. 237 */ 238 static int pcf2123_set_offset(struct device *dev, long offset) 239 { 240 s8 reg; 241 242 if (offset > OFFSET_STEP * 127) 243 reg = 127; 244 else if (offset < OFFSET_STEP * -128) 245 reg = -128; 246 else 247 reg = (s8)((offset + (OFFSET_STEP >> 1)) / OFFSET_STEP); 248 249 /* choose fine offset only for odd values in the normal range */ 250 if (reg & 1 && reg <= 63 && reg >= -64) { 251 /* Normal offset. Clear the coarse bit */ 252 reg &= ~OFFSET_COARSE; 253 } else { 254 /* Coarse offset. Divide by 2 and set the coarse bit */ 255 reg >>= 1; 256 reg |= OFFSET_COARSE; 257 } 258 259 return pcf2123_write_reg(dev, PCF2123_REG_OFFSET, reg); 260 } 261 262 static int pcf2123_rtc_read_time(struct device *dev, struct rtc_time *tm) 263 { 264 u8 rxbuf[7]; 265 int ret; 266 267 ret = pcf2123_read(dev, PCF2123_REG_SC, rxbuf, sizeof(rxbuf)); 268 if (ret < 0) 269 return ret; 270 271 if (rxbuf[0] & OSC_HAS_STOPPED) { 272 dev_info(dev, "clock was stopped. Time is not valid\n"); 273 return -EINVAL; 274 } 275 276 tm->tm_sec = bcd2bin(rxbuf[0] & 0x7F); 277 tm->tm_min = bcd2bin(rxbuf[1] & 0x7F); 278 tm->tm_hour = bcd2bin(rxbuf[2] & 0x3F); /* rtc hr 0-23 */ 279 tm->tm_mday = bcd2bin(rxbuf[3] & 0x3F); 280 tm->tm_wday = rxbuf[4] & 0x07; 281 tm->tm_mon = bcd2bin(rxbuf[5] & 0x1F) - 1; /* rtc mn 1-12 */ 282 tm->tm_year = bcd2bin(rxbuf[6]); 283 if (tm->tm_year < 70) 284 tm->tm_year += 100; /* assume we are in 1970...2069 */ 285 286 dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, " 287 "mday=%d, mon=%d, year=%d, wday=%d\n", 288 __func__, 289 tm->tm_sec, tm->tm_min, tm->tm_hour, 290 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 291 292 return 0; 293 } 294 295 static int pcf2123_rtc_set_time(struct device *dev, struct rtc_time *tm) 296 { 297 u8 txbuf[8]; 298 int ret; 299 300 dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, " 301 "mday=%d, mon=%d, year=%d, wday=%d\n", 302 __func__, 303 tm->tm_sec, tm->tm_min, tm->tm_hour, 304 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 305 306 /* Stop the counter first */ 307 ret = pcf2123_write_reg(dev, PCF2123_REG_CTRL1, CTRL1_STOP); 308 if (ret < 0) 309 return ret; 310 311 /* Set the new time */ 312 txbuf[0] = PCF2123_REG_SC; 313 txbuf[1] = bin2bcd(tm->tm_sec & 0x7F); 314 txbuf[2] = bin2bcd(tm->tm_min & 0x7F); 315 txbuf[3] = bin2bcd(tm->tm_hour & 0x3F); 316 txbuf[4] = bin2bcd(tm->tm_mday & 0x3F); 317 txbuf[5] = tm->tm_wday & 0x07; 318 txbuf[6] = bin2bcd((tm->tm_mon + 1) & 0x1F); /* rtc mn 1-12 */ 319 txbuf[7] = bin2bcd(tm->tm_year < 100 ? tm->tm_year : tm->tm_year - 100); 320 321 ret = pcf2123_write(dev, txbuf, sizeof(txbuf)); 322 if (ret < 0) 323 return ret; 324 325 /* Start the counter */ 326 ret = pcf2123_write_reg(dev, PCF2123_REG_CTRL1, CTRL1_CLEAR); 327 if (ret < 0) 328 return ret; 329 330 return 0; 331 } 332 333 static int pcf2123_reset(struct device *dev) 334 { 335 int ret; 336 u8 rxbuf[2]; 337 338 ret = pcf2123_write_reg(dev, PCF2123_REG_CTRL1, CTRL1_SW_RESET); 339 if (ret < 0) 340 return ret; 341 342 /* Stop the counter */ 343 dev_dbg(dev, "stopping RTC\n"); 344 ret = pcf2123_write_reg(dev, PCF2123_REG_CTRL1, CTRL1_STOP); 345 if (ret < 0) 346 return ret; 347 348 /* See if the counter was actually stopped */ 349 dev_dbg(dev, "checking for presence of RTC\n"); 350 ret = pcf2123_read(dev, PCF2123_REG_CTRL1, rxbuf, sizeof(rxbuf)); 351 if (ret < 0) 352 return ret; 353 354 dev_dbg(dev, "received data from RTC (0x%02X 0x%02X)\n", 355 rxbuf[0], rxbuf[1]); 356 if (!(rxbuf[0] & CTRL1_STOP)) 357 return -ENODEV; 358 359 /* Start the counter */ 360 ret = pcf2123_write_reg(dev, PCF2123_REG_CTRL1, CTRL1_CLEAR); 361 if (ret < 0) 362 return ret; 363 364 return 0; 365 } 366 367 static const struct rtc_class_ops pcf2123_rtc_ops = { 368 .read_time = pcf2123_rtc_read_time, 369 .set_time = pcf2123_rtc_set_time, 370 .read_offset = pcf2123_read_offset, 371 .set_offset = pcf2123_set_offset, 372 373 }; 374 375 static int pcf2123_probe(struct spi_device *spi) 376 { 377 struct rtc_device *rtc; 378 struct rtc_time tm; 379 struct pcf2123_plat_data *pdata; 380 int ret, i; 381 382 pdata = devm_kzalloc(&spi->dev, sizeof(struct pcf2123_plat_data), 383 GFP_KERNEL); 384 if (!pdata) 385 return -ENOMEM; 386 spi->dev.platform_data = pdata; 387 388 ret = pcf2123_rtc_read_time(&spi->dev, &tm); 389 if (ret < 0) { 390 ret = pcf2123_reset(&spi->dev); 391 if (ret < 0) { 392 dev_err(&spi->dev, "chip not found\n"); 393 goto kfree_exit; 394 } 395 } 396 397 dev_info(&spi->dev, "spiclk %u KHz.\n", 398 (spi->max_speed_hz + 500) / 1000); 399 400 /* Finalize the initialization */ 401 rtc = devm_rtc_device_register(&spi->dev, pcf2123_driver.driver.name, 402 &pcf2123_rtc_ops, THIS_MODULE); 403 404 if (IS_ERR(rtc)) { 405 dev_err(&spi->dev, "failed to register.\n"); 406 ret = PTR_ERR(rtc); 407 goto kfree_exit; 408 } 409 410 pdata->rtc = rtc; 411 412 for (i = 0; i < 16; i++) { 413 sysfs_attr_init(&pdata->regs[i].attr.attr); 414 sprintf(pdata->regs[i].name, "%1x", i); 415 pdata->regs[i].attr.attr.mode = S_IRUGO | S_IWUSR; 416 pdata->regs[i].attr.attr.name = pdata->regs[i].name; 417 pdata->regs[i].attr.show = pcf2123_show; 418 pdata->regs[i].attr.store = pcf2123_store; 419 ret = device_create_file(&spi->dev, &pdata->regs[i].attr); 420 if (ret) { 421 dev_err(&spi->dev, "Unable to create sysfs %s\n", 422 pdata->regs[i].name); 423 goto sysfs_exit; 424 } 425 } 426 427 return 0; 428 429 sysfs_exit: 430 for (i--; i >= 0; i--) 431 device_remove_file(&spi->dev, &pdata->regs[i].attr); 432 433 kfree_exit: 434 spi->dev.platform_data = NULL; 435 return ret; 436 } 437 438 static int pcf2123_remove(struct spi_device *spi) 439 { 440 struct pcf2123_plat_data *pdata = dev_get_platdata(&spi->dev); 441 int i; 442 443 if (pdata) { 444 for (i = 0; i < 16; i++) 445 if (pdata->regs[i].name[0]) 446 device_remove_file(&spi->dev, 447 &pdata->regs[i].attr); 448 } 449 450 return 0; 451 } 452 453 #ifdef CONFIG_OF 454 static const struct of_device_id pcf2123_dt_ids[] = { 455 { .compatible = "nxp,rtc-pcf2123", }, 456 { /* sentinel */ } 457 }; 458 MODULE_DEVICE_TABLE(of, pcf2123_dt_ids); 459 #endif 460 461 static struct spi_driver pcf2123_driver = { 462 .driver = { 463 .name = "rtc-pcf2123", 464 .of_match_table = of_match_ptr(pcf2123_dt_ids), 465 }, 466 .probe = pcf2123_probe, 467 .remove = pcf2123_remove, 468 }; 469 470 module_spi_driver(pcf2123_driver); 471 472 MODULE_AUTHOR("Chris Verges <chrisv@cyberswitching.com>"); 473 MODULE_DESCRIPTION("NXP PCF2123 RTC driver"); 474 MODULE_LICENSE("GPL"); 475