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 u32 lp_status; 78 u32 lp_cr; 79 80 spin_lock(&pdata->lock); 81 if (clk_enable(pdata->clk)) { 82 spin_unlock(&pdata->lock); 83 return IRQ_NONE; 84 } 85 86 lp_status = readl(ioaddr + SRTC_LPSR); 87 lp_cr = readl(ioaddr + SRTC_LPCR); 88 89 /* update irq data & counter */ 90 if (lp_status & SRTC_LPSR_ALP) { 91 if (lp_cr & SRTC_LPCR_ALP) 92 rtc_update_irq(pdata->rtc, 1, RTC_AF | RTC_IRQF); 93 94 /* disable further lp alarm interrupts */ 95 lp_cr &= ~(SRTC_LPCR_ALP | SRTC_LPCR_WAE); 96 } 97 98 /* Update interrupt enables */ 99 writel(lp_cr, ioaddr + SRTC_LPCR); 100 101 /* clear interrupt status */ 102 writel(lp_status, ioaddr + SRTC_LPSR); 103 104 mxc_rtc_sync_lp_locked(dev, ioaddr); 105 clk_disable(pdata->clk); 106 spin_unlock(&pdata->lock); 107 return IRQ_HANDLED; 108 } 109 110 /* 111 * Enable clk and aquire spinlock 112 * @return 0 if successful; non-zero otherwise. 113 */ 114 static int mxc_rtc_lock(struct mxc_rtc_data *const pdata) 115 { 116 int ret; 117 118 spin_lock_irq(&pdata->lock); 119 ret = clk_enable(pdata->clk); 120 if (ret) { 121 spin_unlock_irq(&pdata->lock); 122 return ret; 123 } 124 return 0; 125 } 126 127 static int mxc_rtc_unlock(struct mxc_rtc_data *const pdata) 128 { 129 clk_disable(pdata->clk); 130 spin_unlock_irq(&pdata->lock); 131 return 0; 132 } 133 134 /* 135 * This function reads the current RTC time into tm in Gregorian date. 136 * 137 * @param tm contains the RTC time value upon return 138 * 139 * @return 0 if successful; non-zero otherwise. 140 */ 141 static int mxc_rtc_read_time(struct device *dev, struct rtc_time *tm) 142 { 143 struct mxc_rtc_data *pdata = dev_get_drvdata(dev); 144 const int clk_failed = clk_enable(pdata->clk); 145 146 if (!clk_failed) { 147 const time64_t now = readl(pdata->ioaddr + SRTC_LPSCMR); 148 149 rtc_time64_to_tm(now, tm); 150 clk_disable(pdata->clk); 151 return 0; 152 } 153 return clk_failed; 154 } 155 156 /* 157 * This function sets the internal RTC time based on tm in Gregorian date. 158 * 159 * @param tm the time value to be set in the RTC 160 * 161 * @return 0 if successful; non-zero otherwise. 162 */ 163 static int mxc_rtc_set_time(struct device *dev, struct rtc_time *tm) 164 { 165 struct mxc_rtc_data *pdata = dev_get_drvdata(dev); 166 time64_t time = rtc_tm_to_time64(tm); 167 int ret; 168 169 ret = mxc_rtc_lock(pdata); 170 if (ret) 171 return ret; 172 173 writel(time, pdata->ioaddr + SRTC_LPSCMR); 174 mxc_rtc_sync_lp_locked(dev, pdata->ioaddr); 175 return mxc_rtc_unlock(pdata); 176 } 177 178 /* 179 * This function reads the current alarm value into the passed in \b alrm 180 * argument. It updates the \b alrm's pending field value based on the whether 181 * an alarm interrupt occurs or not. 182 * 183 * @param alrm contains the RTC alarm value upon return 184 * 185 * @return 0 if successful; non-zero otherwise. 186 */ 187 static int mxc_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm) 188 { 189 struct mxc_rtc_data *pdata = dev_get_drvdata(dev); 190 void __iomem *ioaddr = pdata->ioaddr; 191 int ret; 192 193 ret = mxc_rtc_lock(pdata); 194 if (ret) 195 return ret; 196 197 rtc_time64_to_tm(readl(ioaddr + SRTC_LPSAR), &alrm->time); 198 alrm->pending = !!(readl(ioaddr + SRTC_LPSR) & SRTC_LPSR_ALP); 199 return mxc_rtc_unlock(pdata); 200 } 201 202 /* 203 * Enable/Disable alarm interrupt 204 * The caller should hold the pdata->lock 205 */ 206 static void mxc_rtc_alarm_irq_enable_locked(struct mxc_rtc_data *pdata, 207 unsigned int enable) 208 { 209 u32 lp_cr = readl(pdata->ioaddr + SRTC_LPCR); 210 211 if (enable) 212 lp_cr |= (SRTC_LPCR_ALP | SRTC_LPCR_WAE); 213 else 214 lp_cr &= ~(SRTC_LPCR_ALP | SRTC_LPCR_WAE); 215 216 writel(lp_cr, pdata->ioaddr + SRTC_LPCR); 217 } 218 219 static int mxc_rtc_alarm_irq_enable(struct device *dev, unsigned int enable) 220 { 221 struct mxc_rtc_data *pdata = dev_get_drvdata(dev); 222 int ret = mxc_rtc_lock(pdata); 223 224 if (ret) 225 return ret; 226 227 mxc_rtc_alarm_irq_enable_locked(pdata, enable); 228 return mxc_rtc_unlock(pdata); 229 } 230 231 /* 232 * This function sets the RTC alarm based on passed in alrm. 233 * 234 * @param alrm the alarm value to be set in the RTC 235 * 236 * @return 0 if successful; non-zero otherwise. 237 */ 238 static int mxc_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm) 239 { 240 const time64_t time = rtc_tm_to_time64(&alrm->time); 241 struct mxc_rtc_data *pdata = dev_get_drvdata(dev); 242 int ret = mxc_rtc_lock(pdata); 243 244 if (ret) 245 return ret; 246 247 writel((u32)time, pdata->ioaddr + SRTC_LPSAR); 248 249 /* clear alarm interrupt status bit */ 250 writel(SRTC_LPSR_ALP, pdata->ioaddr + SRTC_LPSR); 251 mxc_rtc_sync_lp_locked(dev, pdata->ioaddr); 252 253 mxc_rtc_alarm_irq_enable_locked(pdata, alrm->enabled); 254 mxc_rtc_sync_lp_locked(dev, pdata->ioaddr); 255 mxc_rtc_unlock(pdata); 256 return ret; 257 } 258 259 static const struct rtc_class_ops mxc_rtc_ops = { 260 .read_time = mxc_rtc_read_time, 261 .set_time = mxc_rtc_set_time, 262 .read_alarm = mxc_rtc_read_alarm, 263 .set_alarm = mxc_rtc_set_alarm, 264 .alarm_irq_enable = mxc_rtc_alarm_irq_enable, 265 }; 266 267 static int mxc_rtc_wait_for_flag(void __iomem *ioaddr, int flag) 268 { 269 unsigned int timeout = REG_READ_TIMEOUT; 270 271 while (!(readl(ioaddr) & flag)) { 272 if (!--timeout) 273 return -EBUSY; 274 } 275 return 0; 276 } 277 278 static int mxc_rtc_probe(struct platform_device *pdev) 279 { 280 struct mxc_rtc_data *pdata; 281 void __iomem *ioaddr; 282 int ret = 0; 283 284 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL); 285 if (!pdata) 286 return -ENOMEM; 287 288 pdata->ioaddr = devm_platform_ioremap_resource(pdev, 0); 289 if (IS_ERR(pdata->ioaddr)) 290 return PTR_ERR(pdata->ioaddr); 291 292 ioaddr = pdata->ioaddr; 293 294 pdata->clk = devm_clk_get(&pdev->dev, NULL); 295 if (IS_ERR(pdata->clk)) { 296 dev_err(&pdev->dev, "unable to get rtc clock!\n"); 297 return PTR_ERR(pdata->clk); 298 } 299 300 spin_lock_init(&pdata->lock); 301 pdata->irq = platform_get_irq(pdev, 0); 302 if (pdata->irq < 0) 303 return pdata->irq; 304 305 device_init_wakeup(&pdev->dev, 1); 306 ret = dev_pm_set_wake_irq(&pdev->dev, pdata->irq); 307 if (ret) 308 dev_err(&pdev->dev, "failed to enable irq wake\n"); 309 310 ret = clk_prepare_enable(pdata->clk); 311 if (ret) 312 return ret; 313 /* initialize glitch detect */ 314 writel(SRTC_LPPDR_INIT, ioaddr + SRTC_LPPDR); 315 316 /* clear lp interrupt status */ 317 writel(0xFFFFFFFF, ioaddr + SRTC_LPSR); 318 319 /* move out of init state */ 320 writel((SRTC_LPCR_IE | SRTC_LPCR_NSA), ioaddr + SRTC_LPCR); 321 ret = mxc_rtc_wait_for_flag(ioaddr + SRTC_LPSR, SRTC_LPSR_IES); 322 if (ret) { 323 dev_err(&pdev->dev, "Timeout waiting for SRTC_LPSR_IES\n"); 324 clk_disable_unprepare(pdata->clk); 325 return ret; 326 } 327 328 /* move out of non-valid state */ 329 writel((SRTC_LPCR_IE | SRTC_LPCR_NVE | SRTC_LPCR_NSA | 330 SRTC_LPCR_EN_LP), ioaddr + SRTC_LPCR); 331 ret = mxc_rtc_wait_for_flag(ioaddr + SRTC_LPSR, SRTC_LPSR_NVES); 332 if (ret) { 333 dev_err(&pdev->dev, "Timeout waiting for SRTC_LPSR_NVES\n"); 334 clk_disable_unprepare(pdata->clk); 335 return ret; 336 } 337 338 pdata->rtc = devm_rtc_allocate_device(&pdev->dev); 339 if (IS_ERR(pdata->rtc)) 340 return PTR_ERR(pdata->rtc); 341 342 pdata->rtc->ops = &mxc_rtc_ops; 343 pdata->rtc->range_max = U32_MAX; 344 345 clk_disable(pdata->clk); 346 platform_set_drvdata(pdev, pdata); 347 ret = 348 devm_request_irq(&pdev->dev, pdata->irq, mxc_rtc_interrupt, 0, 349 pdev->name, &pdev->dev); 350 if (ret < 0) { 351 dev_err(&pdev->dev, "interrupt not available.\n"); 352 clk_unprepare(pdata->clk); 353 return ret; 354 } 355 356 ret = devm_rtc_register_device(pdata->rtc); 357 if (ret < 0) 358 clk_unprepare(pdata->clk); 359 360 return ret; 361 } 362 363 static int mxc_rtc_remove(struct platform_device *pdev) 364 { 365 struct mxc_rtc_data *pdata = platform_get_drvdata(pdev); 366 367 clk_disable_unprepare(pdata->clk); 368 return 0; 369 } 370 371 static const struct of_device_id mxc_ids[] = { 372 { .compatible = "fsl,imx53-rtc", }, 373 {} 374 }; 375 376 static struct platform_driver mxc_rtc_driver = { 377 .driver = { 378 .name = "mxc_rtc_v2", 379 .of_match_table = mxc_ids, 380 }, 381 .probe = mxc_rtc_probe, 382 .remove = mxc_rtc_remove, 383 }; 384 385 module_platform_driver(mxc_rtc_driver); 386 387 MODULE_AUTHOR("Freescale Semiconductor, Inc."); 388 MODULE_DESCRIPTION("Real Time Clock (RTC) Driver for i.MX53"); 389 MODULE_LICENSE("GPL"); 390