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