1 /* 2 * Real Time Clock driver for Wolfson Microelectronics WM831x 3 * 4 * Copyright (C) 2009 Wolfson Microelectronics PLC. 5 * 6 * Author: Mark Brown <broonie@opensource.wolfsonmicro.com> 7 * 8 * This program is free software; you can redistribute it and/or modify it 9 * under the terms of the GNU General Public License as published by the 10 * Free Software Foundation; either version 2 of the License, or (at your 11 * option) any later version. 12 * 13 */ 14 15 #include <linux/module.h> 16 #include <linux/kernel.h> 17 #include <linux/time.h> 18 #include <linux/rtc.h> 19 #include <linux/slab.h> 20 #include <linux/bcd.h> 21 #include <linux/interrupt.h> 22 #include <linux/ioctl.h> 23 #include <linux/completion.h> 24 #include <linux/mfd/wm831x/core.h> 25 #include <linux/delay.h> 26 #include <linux/platform_device.h> 27 #include <linux/random.h> 28 29 /* 30 * R16416 (0x4020) - RTC Write Counter 31 */ 32 #define WM831X_RTC_WR_CNT_MASK 0xFFFF /* RTC_WR_CNT - [15:0] */ 33 #define WM831X_RTC_WR_CNT_SHIFT 0 /* RTC_WR_CNT - [15:0] */ 34 #define WM831X_RTC_WR_CNT_WIDTH 16 /* RTC_WR_CNT - [15:0] */ 35 36 /* 37 * R16417 (0x4021) - RTC Time 1 38 */ 39 #define WM831X_RTC_TIME_MASK 0xFFFF /* RTC_TIME - [15:0] */ 40 #define WM831X_RTC_TIME_SHIFT 0 /* RTC_TIME - [15:0] */ 41 #define WM831X_RTC_TIME_WIDTH 16 /* RTC_TIME - [15:0] */ 42 43 /* 44 * R16418 (0x4022) - RTC Time 2 45 */ 46 #define WM831X_RTC_TIME_MASK 0xFFFF /* RTC_TIME - [15:0] */ 47 #define WM831X_RTC_TIME_SHIFT 0 /* RTC_TIME - [15:0] */ 48 #define WM831X_RTC_TIME_WIDTH 16 /* RTC_TIME - [15:0] */ 49 50 /* 51 * R16419 (0x4023) - RTC Alarm 1 52 */ 53 #define WM831X_RTC_ALM_MASK 0xFFFF /* RTC_ALM - [15:0] */ 54 #define WM831X_RTC_ALM_SHIFT 0 /* RTC_ALM - [15:0] */ 55 #define WM831X_RTC_ALM_WIDTH 16 /* RTC_ALM - [15:0] */ 56 57 /* 58 * R16420 (0x4024) - RTC Alarm 2 59 */ 60 #define WM831X_RTC_ALM_MASK 0xFFFF /* RTC_ALM - [15:0] */ 61 #define WM831X_RTC_ALM_SHIFT 0 /* RTC_ALM - [15:0] */ 62 #define WM831X_RTC_ALM_WIDTH 16 /* RTC_ALM - [15:0] */ 63 64 /* 65 * R16421 (0x4025) - RTC Control 66 */ 67 #define WM831X_RTC_VALID 0x8000 /* RTC_VALID */ 68 #define WM831X_RTC_VALID_MASK 0x8000 /* RTC_VALID */ 69 #define WM831X_RTC_VALID_SHIFT 15 /* RTC_VALID */ 70 #define WM831X_RTC_VALID_WIDTH 1 /* RTC_VALID */ 71 #define WM831X_RTC_SYNC_BUSY 0x4000 /* RTC_SYNC_BUSY */ 72 #define WM831X_RTC_SYNC_BUSY_MASK 0x4000 /* RTC_SYNC_BUSY */ 73 #define WM831X_RTC_SYNC_BUSY_SHIFT 14 /* RTC_SYNC_BUSY */ 74 #define WM831X_RTC_SYNC_BUSY_WIDTH 1 /* RTC_SYNC_BUSY */ 75 #define WM831X_RTC_ALM_ENA 0x0400 /* RTC_ALM_ENA */ 76 #define WM831X_RTC_ALM_ENA_MASK 0x0400 /* RTC_ALM_ENA */ 77 #define WM831X_RTC_ALM_ENA_SHIFT 10 /* RTC_ALM_ENA */ 78 #define WM831X_RTC_ALM_ENA_WIDTH 1 /* RTC_ALM_ENA */ 79 #define WM831X_RTC_PINT_FREQ_MASK 0x0070 /* RTC_PINT_FREQ - [6:4] */ 80 #define WM831X_RTC_PINT_FREQ_SHIFT 4 /* RTC_PINT_FREQ - [6:4] */ 81 #define WM831X_RTC_PINT_FREQ_WIDTH 3 /* RTC_PINT_FREQ - [6:4] */ 82 83 /* 84 * R16422 (0x4026) - RTC Trim 85 */ 86 #define WM831X_RTC_TRIM_MASK 0x03FF /* RTC_TRIM - [9:0] */ 87 #define WM831X_RTC_TRIM_SHIFT 0 /* RTC_TRIM - [9:0] */ 88 #define WM831X_RTC_TRIM_WIDTH 10 /* RTC_TRIM - [9:0] */ 89 90 #define WM831X_SET_TIME_RETRIES 5 91 #define WM831X_GET_TIME_RETRIES 5 92 93 struct wm831x_rtc { 94 struct wm831x *wm831x; 95 struct rtc_device *rtc; 96 unsigned int alarm_enabled:1; 97 }; 98 99 static void wm831x_rtc_add_randomness(struct wm831x *wm831x) 100 { 101 int ret; 102 u16 reg; 103 104 /* 105 * The write counter contains a pseudo-random number which is 106 * regenerated every time we set the RTC so it should be a 107 * useful per-system source of entropy. 108 */ 109 ret = wm831x_reg_read(wm831x, WM831X_RTC_WRITE_COUNTER); 110 if (ret >= 0) { 111 reg = ret; 112 add_device_randomness(®, sizeof(reg)); 113 } else { 114 dev_warn(wm831x->dev, "Failed to read RTC write counter: %d\n", 115 ret); 116 } 117 } 118 119 /* 120 * Read current time and date in RTC 121 */ 122 static int wm831x_rtc_readtime(struct device *dev, struct rtc_time *tm) 123 { 124 struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev); 125 struct wm831x *wm831x = wm831x_rtc->wm831x; 126 u16 time1[2], time2[2]; 127 int ret; 128 int count = 0; 129 130 /* Has the RTC been programmed? */ 131 ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL); 132 if (ret < 0) { 133 dev_err(dev, "Failed to read RTC control: %d\n", ret); 134 return ret; 135 } 136 if (!(ret & WM831X_RTC_VALID)) { 137 dev_dbg(dev, "RTC not yet configured\n"); 138 return -EINVAL; 139 } 140 141 /* Read twice to make sure we don't read a corrupt, partially 142 * incremented, value. 143 */ 144 do { 145 ret = wm831x_bulk_read(wm831x, WM831X_RTC_TIME_1, 146 2, time1); 147 if (ret != 0) 148 continue; 149 150 ret = wm831x_bulk_read(wm831x, WM831X_RTC_TIME_1, 151 2, time2); 152 if (ret != 0) 153 continue; 154 155 if (memcmp(time1, time2, sizeof(time1)) == 0) { 156 u32 time = (time1[0] << 16) | time1[1]; 157 158 rtc_time_to_tm(time, tm); 159 return rtc_valid_tm(tm); 160 } 161 162 } while (++count < WM831X_GET_TIME_RETRIES); 163 164 dev_err(dev, "Timed out reading current time\n"); 165 166 return -EIO; 167 } 168 169 /* 170 * Set current time and date in RTC 171 */ 172 static int wm831x_rtc_set_mmss(struct device *dev, unsigned long time) 173 { 174 struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev); 175 struct wm831x *wm831x = wm831x_rtc->wm831x; 176 struct rtc_time new_tm; 177 unsigned long new_time; 178 int ret; 179 int count = 0; 180 181 ret = wm831x_reg_write(wm831x, WM831X_RTC_TIME_1, 182 (time >> 16) & 0xffff); 183 if (ret < 0) { 184 dev_err(dev, "Failed to write TIME_1: %d\n", ret); 185 return ret; 186 } 187 188 ret = wm831x_reg_write(wm831x, WM831X_RTC_TIME_2, time & 0xffff); 189 if (ret < 0) { 190 dev_err(dev, "Failed to write TIME_2: %d\n", ret); 191 return ret; 192 } 193 194 /* Wait for the update to complete - should happen first time 195 * round but be conservative. 196 */ 197 do { 198 msleep(1); 199 200 ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL); 201 if (ret < 0) 202 ret = WM831X_RTC_SYNC_BUSY; 203 } while (!(ret & WM831X_RTC_SYNC_BUSY) && 204 ++count < WM831X_SET_TIME_RETRIES); 205 206 if (ret & WM831X_RTC_SYNC_BUSY) { 207 dev_err(dev, "Timed out writing RTC update\n"); 208 return -EIO; 209 } 210 211 /* Check that the update was accepted; security features may 212 * have caused the update to be ignored. 213 */ 214 ret = wm831x_rtc_readtime(dev, &new_tm); 215 if (ret < 0) 216 return ret; 217 218 ret = rtc_tm_to_time(&new_tm, &new_time); 219 if (ret < 0) { 220 dev_err(dev, "Failed to convert time: %d\n", ret); 221 return ret; 222 } 223 224 /* Allow a second of change in case of tick */ 225 if (new_time - time > 1) { 226 dev_err(dev, "RTC update not permitted by hardware\n"); 227 return -EPERM; 228 } 229 230 return 0; 231 } 232 233 /* 234 * Read alarm time and date in RTC 235 */ 236 static int wm831x_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm) 237 { 238 struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev); 239 int ret; 240 u16 data[2]; 241 u32 time; 242 243 ret = wm831x_bulk_read(wm831x_rtc->wm831x, WM831X_RTC_ALARM_1, 244 2, data); 245 if (ret != 0) { 246 dev_err(dev, "Failed to read alarm time: %d\n", ret); 247 return ret; 248 } 249 250 time = (data[0] << 16) | data[1]; 251 252 rtc_time_to_tm(time, &alrm->time); 253 254 ret = wm831x_reg_read(wm831x_rtc->wm831x, WM831X_RTC_CONTROL); 255 if (ret < 0) { 256 dev_err(dev, "Failed to read RTC control: %d\n", ret); 257 return ret; 258 } 259 260 if (ret & WM831X_RTC_ALM_ENA) 261 alrm->enabled = 1; 262 else 263 alrm->enabled = 0; 264 265 return 0; 266 } 267 268 static int wm831x_rtc_stop_alarm(struct wm831x_rtc *wm831x_rtc) 269 { 270 wm831x_rtc->alarm_enabled = 0; 271 272 return wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL, 273 WM831X_RTC_ALM_ENA, 0); 274 } 275 276 static int wm831x_rtc_start_alarm(struct wm831x_rtc *wm831x_rtc) 277 { 278 wm831x_rtc->alarm_enabled = 1; 279 280 return wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL, 281 WM831X_RTC_ALM_ENA, WM831X_RTC_ALM_ENA); 282 } 283 284 static int wm831x_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm) 285 { 286 struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev); 287 struct wm831x *wm831x = wm831x_rtc->wm831x; 288 int ret; 289 unsigned long time; 290 291 ret = rtc_tm_to_time(&alrm->time, &time); 292 if (ret < 0) { 293 dev_err(dev, "Failed to convert time: %d\n", ret); 294 return ret; 295 } 296 297 ret = wm831x_rtc_stop_alarm(wm831x_rtc); 298 if (ret < 0) { 299 dev_err(dev, "Failed to stop alarm: %d\n", ret); 300 return ret; 301 } 302 303 ret = wm831x_reg_write(wm831x, WM831X_RTC_ALARM_1, 304 (time >> 16) & 0xffff); 305 if (ret < 0) { 306 dev_err(dev, "Failed to write ALARM_1: %d\n", ret); 307 return ret; 308 } 309 310 ret = wm831x_reg_write(wm831x, WM831X_RTC_ALARM_2, time & 0xffff); 311 if (ret < 0) { 312 dev_err(dev, "Failed to write ALARM_2: %d\n", ret); 313 return ret; 314 } 315 316 if (alrm->enabled) { 317 ret = wm831x_rtc_start_alarm(wm831x_rtc); 318 if (ret < 0) { 319 dev_err(dev, "Failed to start alarm: %d\n", ret); 320 return ret; 321 } 322 } 323 324 return 0; 325 } 326 327 static int wm831x_rtc_alarm_irq_enable(struct device *dev, 328 unsigned int enabled) 329 { 330 struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev); 331 332 if (enabled) 333 return wm831x_rtc_start_alarm(wm831x_rtc); 334 else 335 return wm831x_rtc_stop_alarm(wm831x_rtc); 336 } 337 338 static irqreturn_t wm831x_alm_irq(int irq, void *data) 339 { 340 struct wm831x_rtc *wm831x_rtc = data; 341 342 rtc_update_irq(wm831x_rtc->rtc, 1, RTC_IRQF | RTC_AF); 343 344 return IRQ_HANDLED; 345 } 346 347 static const struct rtc_class_ops wm831x_rtc_ops = { 348 .read_time = wm831x_rtc_readtime, 349 .set_mmss = wm831x_rtc_set_mmss, 350 .read_alarm = wm831x_rtc_readalarm, 351 .set_alarm = wm831x_rtc_setalarm, 352 .alarm_irq_enable = wm831x_rtc_alarm_irq_enable, 353 }; 354 355 #ifdef CONFIG_PM 356 /* Turn off the alarm if it should not be a wake source. */ 357 static int wm831x_rtc_suspend(struct device *dev) 358 { 359 struct platform_device *pdev = to_platform_device(dev); 360 struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(&pdev->dev); 361 int ret, enable; 362 363 if (wm831x_rtc->alarm_enabled && device_may_wakeup(&pdev->dev)) 364 enable = WM831X_RTC_ALM_ENA; 365 else 366 enable = 0; 367 368 ret = wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL, 369 WM831X_RTC_ALM_ENA, enable); 370 if (ret != 0) 371 dev_err(&pdev->dev, "Failed to update RTC alarm: %d\n", ret); 372 373 return 0; 374 } 375 376 /* Enable the alarm if it should be enabled (in case it was disabled to 377 * prevent use as a wake source). 378 */ 379 static int wm831x_rtc_resume(struct device *dev) 380 { 381 struct platform_device *pdev = to_platform_device(dev); 382 struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(&pdev->dev); 383 int ret; 384 385 if (wm831x_rtc->alarm_enabled) { 386 ret = wm831x_rtc_start_alarm(wm831x_rtc); 387 if (ret != 0) 388 dev_err(&pdev->dev, 389 "Failed to restart RTC alarm: %d\n", ret); 390 } 391 392 return 0; 393 } 394 395 /* Unconditionally disable the alarm */ 396 static int wm831x_rtc_freeze(struct device *dev) 397 { 398 struct platform_device *pdev = to_platform_device(dev); 399 struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(&pdev->dev); 400 int ret; 401 402 ret = wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL, 403 WM831X_RTC_ALM_ENA, 0); 404 if (ret != 0) 405 dev_err(&pdev->dev, "Failed to stop RTC alarm: %d\n", ret); 406 407 return 0; 408 } 409 #else 410 #define wm831x_rtc_suspend NULL 411 #define wm831x_rtc_resume NULL 412 #define wm831x_rtc_freeze NULL 413 #endif 414 415 static int wm831x_rtc_probe(struct platform_device *pdev) 416 { 417 struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent); 418 struct wm831x_rtc *wm831x_rtc; 419 int alm_irq = wm831x_irq(wm831x, platform_get_irq_byname(pdev, "ALM")); 420 int ret = 0; 421 422 wm831x_rtc = devm_kzalloc(&pdev->dev, sizeof(*wm831x_rtc), GFP_KERNEL); 423 if (wm831x_rtc == NULL) 424 return -ENOMEM; 425 426 platform_set_drvdata(pdev, wm831x_rtc); 427 wm831x_rtc->wm831x = wm831x; 428 429 ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL); 430 if (ret < 0) { 431 dev_err(&pdev->dev, "Failed to read RTC control: %d\n", ret); 432 goto err; 433 } 434 if (ret & WM831X_RTC_ALM_ENA) 435 wm831x_rtc->alarm_enabled = 1; 436 437 device_init_wakeup(&pdev->dev, 1); 438 439 wm831x_rtc->rtc = devm_rtc_device_register(&pdev->dev, "wm831x", 440 &wm831x_rtc_ops, THIS_MODULE); 441 if (IS_ERR(wm831x_rtc->rtc)) { 442 ret = PTR_ERR(wm831x_rtc->rtc); 443 goto err; 444 } 445 446 ret = devm_request_threaded_irq(&pdev->dev, alm_irq, NULL, 447 wm831x_alm_irq, 448 IRQF_TRIGGER_RISING, "RTC alarm", 449 wm831x_rtc); 450 if (ret != 0) { 451 dev_err(&pdev->dev, "Failed to request alarm IRQ %d: %d\n", 452 alm_irq, ret); 453 } 454 455 wm831x_rtc_add_randomness(wm831x); 456 457 return 0; 458 459 err: 460 return ret; 461 } 462 463 static const struct dev_pm_ops wm831x_rtc_pm_ops = { 464 .suspend = wm831x_rtc_suspend, 465 .resume = wm831x_rtc_resume, 466 467 .freeze = wm831x_rtc_freeze, 468 .thaw = wm831x_rtc_resume, 469 .restore = wm831x_rtc_resume, 470 471 .poweroff = wm831x_rtc_suspend, 472 }; 473 474 static struct platform_driver wm831x_rtc_driver = { 475 .probe = wm831x_rtc_probe, 476 .driver = { 477 .name = "wm831x-rtc", 478 .pm = &wm831x_rtc_pm_ops, 479 }, 480 }; 481 482 module_platform_driver(wm831x_rtc_driver); 483 484 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>"); 485 MODULE_DESCRIPTION("RTC driver for the WM831x series PMICs"); 486 MODULE_LICENSE("GPL"); 487 MODULE_ALIAS("platform:wm831x-rtc"); 488