1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Real Time Clock (RTC) Driver for i.MX53 4 * Copyright (c) 2004-2011 Freescale Semiconductor, Inc. 5 * Copyright (c) 2017 Beckhoff Automation GmbH & Co. KG 6 */ 7 8 #include <linux/clk.h> 9 #include <linux/io.h> 10 #include <linux/module.h> 11 #include <linux/mod_devicetable.h> 12 #include <linux/platform_device.h> 13 #include <linux/pm_wakeirq.h> 14 #include <linux/rtc.h> 15 16 #define SRTC_LPPDR_INIT 0x41736166 /* init for glitch detect */ 17 18 #define SRTC_LPCR_EN_LP BIT(3) /* lp enable */ 19 #define SRTC_LPCR_WAE BIT(4) /* lp wakeup alarm enable */ 20 #define SRTC_LPCR_ALP BIT(7) /* lp alarm flag */ 21 #define SRTC_LPCR_NSA BIT(11) /* lp non secure access */ 22 #define SRTC_LPCR_NVE BIT(14) /* lp non valid state exit bit */ 23 #define SRTC_LPCR_IE BIT(15) /* lp init state exit bit */ 24 25 #define SRTC_LPSR_ALP BIT(3) /* lp alarm flag */ 26 #define SRTC_LPSR_NVES BIT(14) /* lp non-valid state exit status */ 27 #define SRTC_LPSR_IES BIT(15) /* lp init state exit status */ 28 29 #define SRTC_LPSCMR 0x00 /* LP Secure Counter MSB Reg */ 30 #define SRTC_LPSCLR 0x04 /* LP Secure Counter LSB Reg */ 31 #define SRTC_LPSAR 0x08 /* LP Secure Alarm Reg */ 32 #define SRTC_LPCR 0x10 /* LP Control Reg */ 33 #define SRTC_LPSR 0x14 /* LP Status Reg */ 34 #define SRTC_LPPDR 0x18 /* LP Power Supply Glitch Detector Reg */ 35 36 /* max. number of retries to read registers, 120 was max during test */ 37 #define REG_READ_TIMEOUT 2000 38 39 struct mxc_rtc_data { 40 struct rtc_device *rtc; 41 void __iomem *ioaddr; 42 struct clk *clk; 43 spinlock_t lock; /* protects register access */ 44 int irq; 45 }; 46 47 /* 48 * This function does write synchronization for writes to the lp srtc block. 49 * To take care of the asynchronous CKIL clock, all writes from the IP domain 50 * will be synchronized to the CKIL domain. 51 * The caller should hold the pdata->lock 52 */ 53 static void mxc_rtc_sync_lp_locked(struct device *dev, void __iomem *ioaddr) 54 { 55 unsigned int i; 56 57 /* Wait for 3 CKIL cycles */ 58 for (i = 0; i < 3; i++) { 59 const u32 count = readl(ioaddr + SRTC_LPSCLR); 60 unsigned int timeout = REG_READ_TIMEOUT; 61 62 while ((readl(ioaddr + SRTC_LPSCLR)) == count) { 63 if (!--timeout) { 64 dev_err_once(dev, "SRTC_LPSCLR stuck! Check your hw.\n"); 65 return; 66 } 67 } 68 } 69 } 70 71 /* This function is the RTC interrupt service routine. */ 72 static irqreturn_t mxc_rtc_interrupt(int irq, void *dev_id) 73 { 74 struct device *dev = dev_id; 75 struct mxc_rtc_data *pdata = dev_get_drvdata(dev); 76 void __iomem *ioaddr = pdata->ioaddr; 77 unsigned long flags; 78 u32 lp_status; 79 u32 lp_cr; 80 81 spin_lock_irqsave(&pdata->lock, flags); 82 if (clk_enable(pdata->clk)) { 83 spin_unlock_irqrestore(&pdata->lock, flags); 84 return IRQ_NONE; 85 } 86 87 lp_status = readl(ioaddr + SRTC_LPSR); 88 lp_cr = readl(ioaddr + SRTC_LPCR); 89 90 /* update irq data & counter */ 91 if (lp_status & SRTC_LPSR_ALP) { 92 if (lp_cr & SRTC_LPCR_ALP) 93 rtc_update_irq(pdata->rtc, 1, RTC_AF | RTC_IRQF); 94 95 /* disable further lp alarm interrupts */ 96 lp_cr &= ~(SRTC_LPCR_ALP | SRTC_LPCR_WAE); 97 } 98 99 /* Update interrupt enables */ 100 writel(lp_cr, ioaddr + SRTC_LPCR); 101 102 /* clear interrupt status */ 103 writel(lp_status, ioaddr + SRTC_LPSR); 104 105 mxc_rtc_sync_lp_locked(dev, ioaddr); 106 clk_disable(pdata->clk); 107 spin_unlock_irqrestore(&pdata->lock, flags); 108 return IRQ_HANDLED; 109 } 110 111 /* 112 * Enable clk and aquire spinlock 113 * @return 0 if successful; non-zero otherwise. 114 */ 115 static int mxc_rtc_lock(struct mxc_rtc_data *const pdata) 116 { 117 int ret; 118 119 spin_lock_irq(&pdata->lock); 120 ret = clk_enable(pdata->clk); 121 if (ret) { 122 spin_unlock_irq(&pdata->lock); 123 return ret; 124 } 125 return 0; 126 } 127 128 static int mxc_rtc_unlock(struct mxc_rtc_data *const pdata) 129 { 130 clk_disable(pdata->clk); 131 spin_unlock_irq(&pdata->lock); 132 return 0; 133 } 134 135 /* 136 * This function reads the current RTC time into tm in Gregorian date. 137 * 138 * @param tm contains the RTC time value upon return 139 * 140 * @return 0 if successful; non-zero otherwise. 141 */ 142 static int mxc_rtc_read_time(struct device *dev, struct rtc_time *tm) 143 { 144 struct mxc_rtc_data *pdata = dev_get_drvdata(dev); 145 const int clk_failed = clk_enable(pdata->clk); 146 147 if (!clk_failed) { 148 const time64_t now = readl(pdata->ioaddr + SRTC_LPSCMR); 149 150 rtc_time64_to_tm(now, tm); 151 clk_disable(pdata->clk); 152 return 0; 153 } 154 return clk_failed; 155 } 156 157 /* 158 * This function sets the internal RTC time based on tm in Gregorian date. 159 * 160 * @param tm the time value to be set in the RTC 161 * 162 * @return 0 if successful; non-zero otherwise. 163 */ 164 static int mxc_rtc_set_time(struct device *dev, struct rtc_time *tm) 165 { 166 struct mxc_rtc_data *pdata = dev_get_drvdata(dev); 167 time64_t time = rtc_tm_to_time64(tm); 168 int ret; 169 170 ret = mxc_rtc_lock(pdata); 171 if (ret) 172 return ret; 173 174 writel(time, pdata->ioaddr + SRTC_LPSCMR); 175 mxc_rtc_sync_lp_locked(dev, pdata->ioaddr); 176 return mxc_rtc_unlock(pdata); 177 } 178 179 /* 180 * This function reads the current alarm value into the passed in \b alrm 181 * argument. It updates the \b alrm's pending field value based on the whether 182 * an alarm interrupt occurs or not. 183 * 184 * @param alrm contains the RTC alarm value upon return 185 * 186 * @return 0 if successful; non-zero otherwise. 187 */ 188 static int mxc_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm) 189 { 190 struct mxc_rtc_data *pdata = dev_get_drvdata(dev); 191 void __iomem *ioaddr = pdata->ioaddr; 192 int ret; 193 194 ret = mxc_rtc_lock(pdata); 195 if (ret) 196 return ret; 197 198 rtc_time64_to_tm(readl(ioaddr + SRTC_LPSAR), &alrm->time); 199 alrm->pending = !!(readl(ioaddr + SRTC_LPSR) & SRTC_LPSR_ALP); 200 return mxc_rtc_unlock(pdata); 201 } 202 203 /* 204 * Enable/Disable alarm interrupt 205 * The caller should hold the pdata->lock 206 */ 207 static void mxc_rtc_alarm_irq_enable_locked(struct mxc_rtc_data *pdata, 208 unsigned int enable) 209 { 210 u32 lp_cr = readl(pdata->ioaddr + SRTC_LPCR); 211 212 if (enable) 213 lp_cr |= (SRTC_LPCR_ALP | SRTC_LPCR_WAE); 214 else 215 lp_cr &= ~(SRTC_LPCR_ALP | SRTC_LPCR_WAE); 216 217 writel(lp_cr, pdata->ioaddr + SRTC_LPCR); 218 } 219 220 static int mxc_rtc_alarm_irq_enable(struct device *dev, unsigned int enable) 221 { 222 struct mxc_rtc_data *pdata = dev_get_drvdata(dev); 223 int ret = mxc_rtc_lock(pdata); 224 225 if (ret) 226 return ret; 227 228 mxc_rtc_alarm_irq_enable_locked(pdata, enable); 229 return mxc_rtc_unlock(pdata); 230 } 231 232 /* 233 * This function sets the RTC alarm based on passed in alrm. 234 * 235 * @param alrm the alarm value to be set in the RTC 236 * 237 * @return 0 if successful; non-zero otherwise. 238 */ 239 static int mxc_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm) 240 { 241 const time64_t time = rtc_tm_to_time64(&alrm->time); 242 struct mxc_rtc_data *pdata = dev_get_drvdata(dev); 243 int ret = mxc_rtc_lock(pdata); 244 245 if (ret) 246 return ret; 247 248 writel((u32)time, pdata->ioaddr + SRTC_LPSAR); 249 250 /* clear alarm interrupt status bit */ 251 writel(SRTC_LPSR_ALP, pdata->ioaddr + SRTC_LPSR); 252 mxc_rtc_sync_lp_locked(dev, pdata->ioaddr); 253 254 mxc_rtc_alarm_irq_enable_locked(pdata, alrm->enabled); 255 mxc_rtc_sync_lp_locked(dev, pdata->ioaddr); 256 mxc_rtc_unlock(pdata); 257 return ret; 258 } 259 260 static const struct rtc_class_ops mxc_rtc_ops = { 261 .read_time = mxc_rtc_read_time, 262 .set_time = mxc_rtc_set_time, 263 .read_alarm = mxc_rtc_read_alarm, 264 .set_alarm = mxc_rtc_set_alarm, 265 .alarm_irq_enable = mxc_rtc_alarm_irq_enable, 266 }; 267 268 static int mxc_rtc_wait_for_flag(void __iomem *ioaddr, int flag) 269 { 270 unsigned int timeout = REG_READ_TIMEOUT; 271 272 while (!(readl(ioaddr) & flag)) { 273 if (!--timeout) 274 return -EBUSY; 275 } 276 return 0; 277 } 278 279 static int mxc_rtc_probe(struct platform_device *pdev) 280 { 281 struct mxc_rtc_data *pdata; 282 struct resource *res; 283 void __iomem *ioaddr; 284 int ret = 0; 285 286 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL); 287 if (!pdata) 288 return -ENOMEM; 289 290 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 291 pdata->ioaddr = devm_ioremap_resource(&pdev->dev, res); 292 if (IS_ERR(pdata->ioaddr)) 293 return PTR_ERR(pdata->ioaddr); 294 295 ioaddr = pdata->ioaddr; 296 297 pdata->clk = devm_clk_get(&pdev->dev, NULL); 298 if (IS_ERR(pdata->clk)) { 299 dev_err(&pdev->dev, "unable to get rtc clock!\n"); 300 return PTR_ERR(pdata->clk); 301 } 302 303 spin_lock_init(&pdata->lock); 304 pdata->irq = platform_get_irq(pdev, 0); 305 if (pdata->irq < 0) 306 return pdata->irq; 307 308 device_init_wakeup(&pdev->dev, 1); 309 ret = dev_pm_set_wake_irq(&pdev->dev, pdata->irq); 310 if (ret) 311 dev_err(&pdev->dev, "failed to enable irq wake\n"); 312 313 ret = clk_prepare_enable(pdata->clk); 314 if (ret) 315 return ret; 316 /* initialize glitch detect */ 317 writel(SRTC_LPPDR_INIT, ioaddr + SRTC_LPPDR); 318 319 /* clear lp interrupt status */ 320 writel(0xFFFFFFFF, ioaddr + SRTC_LPSR); 321 322 /* move out of init state */ 323 writel((SRTC_LPCR_IE | SRTC_LPCR_NSA), ioaddr + SRTC_LPCR); 324 ret = mxc_rtc_wait_for_flag(ioaddr + SRTC_LPSR, SRTC_LPSR_IES); 325 if (ret) { 326 dev_err(&pdev->dev, "Timeout waiting for SRTC_LPSR_IES\n"); 327 clk_disable_unprepare(pdata->clk); 328 return ret; 329 } 330 331 /* move out of non-valid state */ 332 writel((SRTC_LPCR_IE | SRTC_LPCR_NVE | SRTC_LPCR_NSA | 333 SRTC_LPCR_EN_LP), ioaddr + SRTC_LPCR); 334 ret = mxc_rtc_wait_for_flag(ioaddr + SRTC_LPSR, SRTC_LPSR_NVES); 335 if (ret) { 336 dev_err(&pdev->dev, "Timeout waiting for SRTC_LPSR_NVES\n"); 337 clk_disable_unprepare(pdata->clk); 338 return ret; 339 } 340 341 pdata->rtc = devm_rtc_allocate_device(&pdev->dev); 342 if (IS_ERR(pdata->rtc)) 343 return PTR_ERR(pdata->rtc); 344 345 pdata->rtc->ops = &mxc_rtc_ops; 346 pdata->rtc->range_max = U32_MAX; 347 348 clk_disable(pdata->clk); 349 platform_set_drvdata(pdev, pdata); 350 ret = 351 devm_request_irq(&pdev->dev, pdata->irq, mxc_rtc_interrupt, 0, 352 pdev->name, &pdev->dev); 353 if (ret < 0) { 354 dev_err(&pdev->dev, "interrupt not available.\n"); 355 clk_unprepare(pdata->clk); 356 return ret; 357 } 358 359 ret = rtc_register_device(pdata->rtc); 360 if (ret < 0) 361 clk_unprepare(pdata->clk); 362 363 return ret; 364 } 365 366 static int mxc_rtc_remove(struct platform_device *pdev) 367 { 368 struct mxc_rtc_data *pdata = platform_get_drvdata(pdev); 369 370 clk_disable_unprepare(pdata->clk); 371 return 0; 372 } 373 374 static const struct of_device_id mxc_ids[] = { 375 { .compatible = "fsl,imx53-rtc", }, 376 {} 377 }; 378 379 static struct platform_driver mxc_rtc_driver = { 380 .driver = { 381 .name = "mxc_rtc_v2", 382 .of_match_table = mxc_ids, 383 }, 384 .probe = mxc_rtc_probe, 385 .remove = mxc_rtc_remove, 386 }; 387 388 module_platform_driver(mxc_rtc_driver); 389 390 MODULE_AUTHOR("Freescale Semiconductor, Inc."); 391 MODULE_DESCRIPTION("Real Time Clock (RTC) Driver for i.MX53"); 392 MODULE_LICENSE("GPL"); 393