1 // SPDX-License-Identifier: GPL-2.0+ 2 // 3 // Copyright (C) 2011-2012 Freescale Semiconductor, Inc. 4 5 #include <linux/init.h> 6 #include <linux/io.h> 7 #include <linux/kernel.h> 8 #include <linux/module.h> 9 #include <linux/of.h> 10 #include <linux/of_device.h> 11 #include <linux/platform_device.h> 12 #include <linux/rtc.h> 13 #include <linux/clk.h> 14 #include <linux/mfd/syscon.h> 15 #include <linux/regmap.h> 16 17 #define SNVS_LPREGISTER_OFFSET 0x34 18 19 /* These register offsets are relative to LP (Low Power) range */ 20 #define SNVS_LPCR 0x04 21 #define SNVS_LPSR 0x18 22 #define SNVS_LPSRTCMR 0x1c 23 #define SNVS_LPSRTCLR 0x20 24 #define SNVS_LPTAR 0x24 25 #define SNVS_LPPGDR 0x30 26 27 #define SNVS_LPCR_SRTC_ENV (1 << 0) 28 #define SNVS_LPCR_LPTA_EN (1 << 1) 29 #define SNVS_LPCR_LPWUI_EN (1 << 3) 30 #define SNVS_LPSR_LPTA (1 << 0) 31 32 #define SNVS_LPPGDR_INIT 0x41736166 33 #define CNTR_TO_SECS_SH 15 34 35 struct snvs_rtc_data { 36 struct rtc_device *rtc; 37 struct regmap *regmap; 38 int offset; 39 int irq; 40 struct clk *clk; 41 }; 42 43 /* Read 64 bit timer register, which could be in inconsistent state */ 44 static u64 rtc_read_lpsrt(struct snvs_rtc_data *data) 45 { 46 u32 msb, lsb; 47 48 regmap_read(data->regmap, data->offset + SNVS_LPSRTCMR, &msb); 49 regmap_read(data->regmap, data->offset + SNVS_LPSRTCLR, &lsb); 50 return (u64)msb << 32 | lsb; 51 } 52 53 /* Read the secure real time counter, taking care to deal with the cases of the 54 * counter updating while being read. 55 */ 56 static u32 rtc_read_lp_counter(struct snvs_rtc_data *data) 57 { 58 u64 read1, read2; 59 unsigned int timeout = 100; 60 61 /* As expected, the registers might update between the read of the LSB 62 * reg and the MSB reg. It's also possible that one register might be 63 * in partially modified state as well. 64 */ 65 read1 = rtc_read_lpsrt(data); 66 do { 67 read2 = read1; 68 read1 = rtc_read_lpsrt(data); 69 } while (read1 != read2 && --timeout); 70 if (!timeout) 71 dev_err(&data->rtc->dev, "Timeout trying to get valid LPSRT Counter read\n"); 72 73 /* Convert 47-bit counter to 32-bit raw second count */ 74 return (u32) (read1 >> CNTR_TO_SECS_SH); 75 } 76 77 /* Just read the lsb from the counter, dealing with inconsistent state */ 78 static int rtc_read_lp_counter_lsb(struct snvs_rtc_data *data, u32 *lsb) 79 { 80 u32 count1, count2; 81 unsigned int timeout = 100; 82 83 regmap_read(data->regmap, data->offset + SNVS_LPSRTCLR, &count1); 84 do { 85 count2 = count1; 86 regmap_read(data->regmap, data->offset + SNVS_LPSRTCLR, &count1); 87 } while (count1 != count2 && --timeout); 88 if (!timeout) { 89 dev_err(&data->rtc->dev, "Timeout trying to get valid LPSRT Counter read\n"); 90 return -ETIMEDOUT; 91 } 92 93 *lsb = count1; 94 return 0; 95 } 96 97 static int rtc_write_sync_lp(struct snvs_rtc_data *data) 98 { 99 u32 count1, count2; 100 u32 elapsed; 101 unsigned int timeout = 1000; 102 int ret; 103 104 ret = rtc_read_lp_counter_lsb(data, &count1); 105 if (ret) 106 return ret; 107 108 /* Wait for 3 CKIL cycles, about 61.0-91.5 µs */ 109 do { 110 ret = rtc_read_lp_counter_lsb(data, &count2); 111 if (ret) 112 return ret; 113 elapsed = count2 - count1; /* wrap around _is_ handled! */ 114 } while (elapsed < 3 && --timeout); 115 if (!timeout) { 116 dev_err(&data->rtc->dev, "Timeout waiting for LPSRT Counter to change\n"); 117 return -ETIMEDOUT; 118 } 119 return 0; 120 } 121 122 static int snvs_rtc_enable(struct snvs_rtc_data *data, bool enable) 123 { 124 int timeout = 1000; 125 u32 lpcr; 126 127 regmap_update_bits(data->regmap, data->offset + SNVS_LPCR, SNVS_LPCR_SRTC_ENV, 128 enable ? SNVS_LPCR_SRTC_ENV : 0); 129 130 while (--timeout) { 131 regmap_read(data->regmap, data->offset + SNVS_LPCR, &lpcr); 132 133 if (enable) { 134 if (lpcr & SNVS_LPCR_SRTC_ENV) 135 break; 136 } else { 137 if (!(lpcr & SNVS_LPCR_SRTC_ENV)) 138 break; 139 } 140 } 141 142 if (!timeout) 143 return -ETIMEDOUT; 144 145 return 0; 146 } 147 148 static int snvs_rtc_read_time(struct device *dev, struct rtc_time *tm) 149 { 150 struct snvs_rtc_data *data = dev_get_drvdata(dev); 151 unsigned long time = rtc_read_lp_counter(data); 152 153 rtc_time_to_tm(time, tm); 154 155 return 0; 156 } 157 158 static int snvs_rtc_set_time(struct device *dev, struct rtc_time *tm) 159 { 160 struct snvs_rtc_data *data = dev_get_drvdata(dev); 161 unsigned long time; 162 int ret; 163 164 rtc_tm_to_time(tm, &time); 165 166 /* Disable RTC first */ 167 ret = snvs_rtc_enable(data, false); 168 if (ret) 169 return ret; 170 171 /* Write 32-bit time to 47-bit timer, leaving 15 LSBs blank */ 172 regmap_write(data->regmap, data->offset + SNVS_LPSRTCLR, time << CNTR_TO_SECS_SH); 173 regmap_write(data->regmap, data->offset + SNVS_LPSRTCMR, time >> (32 - CNTR_TO_SECS_SH)); 174 175 /* Enable RTC again */ 176 ret = snvs_rtc_enable(data, true); 177 178 return ret; 179 } 180 181 static int snvs_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm) 182 { 183 struct snvs_rtc_data *data = dev_get_drvdata(dev); 184 u32 lptar, lpsr; 185 186 regmap_read(data->regmap, data->offset + SNVS_LPTAR, &lptar); 187 rtc_time_to_tm(lptar, &alrm->time); 188 189 regmap_read(data->regmap, data->offset + SNVS_LPSR, &lpsr); 190 alrm->pending = (lpsr & SNVS_LPSR_LPTA) ? 1 : 0; 191 192 return 0; 193 } 194 195 static int snvs_rtc_alarm_irq_enable(struct device *dev, unsigned int enable) 196 { 197 struct snvs_rtc_data *data = dev_get_drvdata(dev); 198 199 regmap_update_bits(data->regmap, data->offset + SNVS_LPCR, 200 (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN), 201 enable ? (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN) : 0); 202 203 return rtc_write_sync_lp(data); 204 } 205 206 static int snvs_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm) 207 { 208 struct snvs_rtc_data *data = dev_get_drvdata(dev); 209 struct rtc_time *alrm_tm = &alrm->time; 210 unsigned long time; 211 int ret; 212 213 rtc_tm_to_time(alrm_tm, &time); 214 215 regmap_update_bits(data->regmap, data->offset + SNVS_LPCR, SNVS_LPCR_LPTA_EN, 0); 216 ret = rtc_write_sync_lp(data); 217 if (ret) 218 return ret; 219 regmap_write(data->regmap, data->offset + SNVS_LPTAR, time); 220 221 /* Clear alarm interrupt status bit */ 222 regmap_write(data->regmap, data->offset + SNVS_LPSR, SNVS_LPSR_LPTA); 223 224 return snvs_rtc_alarm_irq_enable(dev, alrm->enabled); 225 } 226 227 static const struct rtc_class_ops snvs_rtc_ops = { 228 .read_time = snvs_rtc_read_time, 229 .set_time = snvs_rtc_set_time, 230 .read_alarm = snvs_rtc_read_alarm, 231 .set_alarm = snvs_rtc_set_alarm, 232 .alarm_irq_enable = snvs_rtc_alarm_irq_enable, 233 }; 234 235 static irqreturn_t snvs_rtc_irq_handler(int irq, void *dev_id) 236 { 237 struct device *dev = dev_id; 238 struct snvs_rtc_data *data = dev_get_drvdata(dev); 239 u32 lpsr; 240 u32 events = 0; 241 242 regmap_read(data->regmap, data->offset + SNVS_LPSR, &lpsr); 243 244 if (lpsr & SNVS_LPSR_LPTA) { 245 events |= (RTC_AF | RTC_IRQF); 246 247 /* RTC alarm should be one-shot */ 248 snvs_rtc_alarm_irq_enable(dev, 0); 249 250 rtc_update_irq(data->rtc, 1, events); 251 } 252 253 /* clear interrupt status */ 254 regmap_write(data->regmap, data->offset + SNVS_LPSR, lpsr); 255 256 return events ? IRQ_HANDLED : IRQ_NONE; 257 } 258 259 static const struct regmap_config snvs_rtc_config = { 260 .reg_bits = 32, 261 .val_bits = 32, 262 .reg_stride = 4, 263 }; 264 265 static int snvs_rtc_probe(struct platform_device *pdev) 266 { 267 struct snvs_rtc_data *data; 268 struct resource *res; 269 int ret; 270 void __iomem *mmio; 271 272 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); 273 if (!data) 274 return -ENOMEM; 275 276 data->regmap = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "regmap"); 277 278 if (IS_ERR(data->regmap)) { 279 dev_warn(&pdev->dev, "snvs rtc: you use old dts file, please update it\n"); 280 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 281 282 mmio = devm_ioremap_resource(&pdev->dev, res); 283 if (IS_ERR(mmio)) 284 return PTR_ERR(mmio); 285 286 data->regmap = devm_regmap_init_mmio(&pdev->dev, mmio, &snvs_rtc_config); 287 } else { 288 data->offset = SNVS_LPREGISTER_OFFSET; 289 of_property_read_u32(pdev->dev.of_node, "offset", &data->offset); 290 } 291 292 if (IS_ERR(data->regmap)) { 293 dev_err(&pdev->dev, "Can't find snvs syscon\n"); 294 return -ENODEV; 295 } 296 297 data->irq = platform_get_irq(pdev, 0); 298 if (data->irq < 0) 299 return data->irq; 300 301 data->clk = devm_clk_get(&pdev->dev, "snvs-rtc"); 302 if (IS_ERR(data->clk)) { 303 data->clk = NULL; 304 } else { 305 ret = clk_prepare_enable(data->clk); 306 if (ret) { 307 dev_err(&pdev->dev, 308 "Could not prepare or enable the snvs clock\n"); 309 return ret; 310 } 311 } 312 313 platform_set_drvdata(pdev, data); 314 315 /* Initialize glitch detect */ 316 regmap_write(data->regmap, data->offset + SNVS_LPPGDR, SNVS_LPPGDR_INIT); 317 318 /* Clear interrupt status */ 319 regmap_write(data->regmap, data->offset + SNVS_LPSR, 0xffffffff); 320 321 /* Enable RTC */ 322 ret = snvs_rtc_enable(data, true); 323 if (ret) { 324 dev_err(&pdev->dev, "failed to enable rtc %d\n", ret); 325 goto error_rtc_device_register; 326 } 327 328 device_init_wakeup(&pdev->dev, true); 329 330 ret = devm_request_irq(&pdev->dev, data->irq, snvs_rtc_irq_handler, 331 IRQF_SHARED, "rtc alarm", &pdev->dev); 332 if (ret) { 333 dev_err(&pdev->dev, "failed to request irq %d: %d\n", 334 data->irq, ret); 335 goto error_rtc_device_register; 336 } 337 338 data->rtc = devm_rtc_device_register(&pdev->dev, pdev->name, 339 &snvs_rtc_ops, THIS_MODULE); 340 if (IS_ERR(data->rtc)) { 341 ret = PTR_ERR(data->rtc); 342 dev_err(&pdev->dev, "failed to register rtc: %d\n", ret); 343 goto error_rtc_device_register; 344 } 345 346 return 0; 347 348 error_rtc_device_register: 349 if (data->clk) 350 clk_disable_unprepare(data->clk); 351 352 return ret; 353 } 354 355 #ifdef CONFIG_PM_SLEEP 356 static int snvs_rtc_suspend(struct device *dev) 357 { 358 struct snvs_rtc_data *data = dev_get_drvdata(dev); 359 360 if (device_may_wakeup(dev)) 361 return enable_irq_wake(data->irq); 362 363 return 0; 364 } 365 366 static int snvs_rtc_suspend_noirq(struct device *dev) 367 { 368 struct snvs_rtc_data *data = dev_get_drvdata(dev); 369 370 if (data->clk) 371 clk_disable_unprepare(data->clk); 372 373 return 0; 374 } 375 376 static int snvs_rtc_resume(struct device *dev) 377 { 378 struct snvs_rtc_data *data = dev_get_drvdata(dev); 379 380 if (device_may_wakeup(dev)) 381 return disable_irq_wake(data->irq); 382 383 return 0; 384 } 385 386 static int snvs_rtc_resume_noirq(struct device *dev) 387 { 388 struct snvs_rtc_data *data = dev_get_drvdata(dev); 389 390 if (data->clk) 391 return clk_prepare_enable(data->clk); 392 393 return 0; 394 } 395 396 static const struct dev_pm_ops snvs_rtc_pm_ops = { 397 .suspend = snvs_rtc_suspend, 398 .suspend_noirq = snvs_rtc_suspend_noirq, 399 .resume = snvs_rtc_resume, 400 .resume_noirq = snvs_rtc_resume_noirq, 401 }; 402 403 #define SNVS_RTC_PM_OPS (&snvs_rtc_pm_ops) 404 405 #else 406 407 #define SNVS_RTC_PM_OPS NULL 408 409 #endif 410 411 static const struct of_device_id snvs_dt_ids[] = { 412 { .compatible = "fsl,sec-v4.0-mon-rtc-lp", }, 413 { /* sentinel */ } 414 }; 415 MODULE_DEVICE_TABLE(of, snvs_dt_ids); 416 417 static struct platform_driver snvs_rtc_driver = { 418 .driver = { 419 .name = "snvs_rtc", 420 .pm = SNVS_RTC_PM_OPS, 421 .of_match_table = snvs_dt_ids, 422 }, 423 .probe = snvs_rtc_probe, 424 }; 425 module_platform_driver(snvs_rtc_driver); 426 427 MODULE_AUTHOR("Freescale Semiconductor, Inc."); 428 MODULE_DESCRIPTION("Freescale SNVS RTC Driver"); 429 MODULE_LICENSE("GPL"); 430