1 /* 2 * rtc-st-lpc.c - ST's LPC RTC, powered by the Low Power Timer 3 * 4 * Copyright (C) 2014 STMicroelectronics Limited 5 * 6 * Author: David Paris <david.paris@st.com> for STMicroelectronics 7 * Lee Jones <lee.jones@linaro.org> for STMicroelectronics 8 * 9 * Based on the original driver written by Stuart Menefy. 10 * 11 * This program is free software; you can redistribute it and/or 12 * modify it under the terms of the GNU General Public Licence 13 * as published by the Free Software Foundation; either version 14 * 2 of the Licence, or (at your option) any later version. 15 */ 16 17 #include <linux/clk.h> 18 #include <linux/delay.h> 19 #include <linux/init.h> 20 #include <linux/io.h> 21 #include <linux/irq.h> 22 #include <linux/kernel.h> 23 #include <linux/module.h> 24 #include <linux/of.h> 25 #include <linux/of_irq.h> 26 #include <linux/platform_device.h> 27 #include <linux/rtc.h> 28 29 #include <dt-bindings/mfd/st-lpc.h> 30 31 /* Low Power Timer */ 32 #define LPC_LPT_LSB_OFF 0x400 33 #define LPC_LPT_MSB_OFF 0x404 34 #define LPC_LPT_START_OFF 0x408 35 36 /* Low Power Alarm */ 37 #define LPC_LPA_LSB_OFF 0x410 38 #define LPC_LPA_MSB_OFF 0x414 39 #define LPC_LPA_START_OFF 0x418 40 41 /* LPC as WDT */ 42 #define LPC_WDT_OFF 0x510 43 #define LPC_WDT_FLAG_OFF 0x514 44 45 struct st_rtc { 46 struct rtc_device *rtc_dev; 47 struct rtc_wkalrm alarm; 48 struct resource *res; 49 struct clk *clk; 50 unsigned long clkrate; 51 void __iomem *ioaddr; 52 bool irq_enabled:1; 53 spinlock_t lock; 54 short irq; 55 }; 56 57 static void st_rtc_set_hw_alarm(struct st_rtc *rtc, 58 unsigned long msb, unsigned long lsb) 59 { 60 unsigned long flags; 61 62 spin_lock_irqsave(&rtc->lock, flags); 63 64 writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF); 65 66 writel_relaxed(msb, rtc->ioaddr + LPC_LPA_MSB_OFF); 67 writel_relaxed(lsb, rtc->ioaddr + LPC_LPA_LSB_OFF); 68 writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF); 69 70 writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF); 71 72 spin_unlock_irqrestore(&rtc->lock, flags); 73 } 74 75 static irqreturn_t st_rtc_handler(int this_irq, void *data) 76 { 77 struct st_rtc *rtc = (struct st_rtc *)data; 78 79 rtc_update_irq(rtc->rtc_dev, 1, RTC_AF); 80 81 return IRQ_HANDLED; 82 } 83 84 static int st_rtc_read_time(struct device *dev, struct rtc_time *tm) 85 { 86 struct st_rtc *rtc = dev_get_drvdata(dev); 87 unsigned long lpt_lsb, lpt_msb; 88 unsigned long long lpt; 89 unsigned long flags; 90 91 spin_lock_irqsave(&rtc->lock, flags); 92 93 do { 94 lpt_msb = readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF); 95 lpt_lsb = readl_relaxed(rtc->ioaddr + LPC_LPT_LSB_OFF); 96 } while (readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF) != lpt_msb); 97 98 spin_unlock_irqrestore(&rtc->lock, flags); 99 100 lpt = ((unsigned long long)lpt_msb << 32) | lpt_lsb; 101 do_div(lpt, rtc->clkrate); 102 rtc_time_to_tm(lpt, tm); 103 104 return 0; 105 } 106 107 static int st_rtc_set_time(struct device *dev, struct rtc_time *tm) 108 { 109 struct st_rtc *rtc = dev_get_drvdata(dev); 110 unsigned long long lpt; 111 unsigned long secs, flags; 112 int ret; 113 114 ret = rtc_tm_to_time(tm, &secs); 115 if (ret) 116 return ret; 117 118 lpt = (unsigned long long)secs * rtc->clkrate; 119 120 spin_lock_irqsave(&rtc->lock, flags); 121 122 writel_relaxed(lpt >> 32, rtc->ioaddr + LPC_LPT_MSB_OFF); 123 writel_relaxed(lpt, rtc->ioaddr + LPC_LPT_LSB_OFF); 124 writel_relaxed(1, rtc->ioaddr + LPC_LPT_START_OFF); 125 126 spin_unlock_irqrestore(&rtc->lock, flags); 127 128 return 0; 129 } 130 131 static int st_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm) 132 { 133 struct st_rtc *rtc = dev_get_drvdata(dev); 134 unsigned long flags; 135 136 spin_lock_irqsave(&rtc->lock, flags); 137 138 memcpy(wkalrm, &rtc->alarm, sizeof(struct rtc_wkalrm)); 139 140 spin_unlock_irqrestore(&rtc->lock, flags); 141 142 return 0; 143 } 144 145 static int st_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled) 146 { 147 struct st_rtc *rtc = dev_get_drvdata(dev); 148 149 if (enabled && !rtc->irq_enabled) { 150 enable_irq(rtc->irq); 151 rtc->irq_enabled = true; 152 } else if (!enabled && rtc->irq_enabled) { 153 disable_irq(rtc->irq); 154 rtc->irq_enabled = false; 155 } 156 157 return 0; 158 } 159 160 static int st_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t) 161 { 162 struct st_rtc *rtc = dev_get_drvdata(dev); 163 struct rtc_time now; 164 unsigned long now_secs; 165 unsigned long alarm_secs; 166 unsigned long long lpa; 167 168 st_rtc_read_time(dev, &now); 169 rtc_tm_to_time(&now, &now_secs); 170 rtc_tm_to_time(&t->time, &alarm_secs); 171 172 /* Invalid alarm time */ 173 if (now_secs > alarm_secs) 174 return -EINVAL; 175 176 memcpy(&rtc->alarm, t, sizeof(struct rtc_wkalrm)); 177 178 /* Now many secs to fire */ 179 alarm_secs -= now_secs; 180 lpa = (unsigned long long)alarm_secs * rtc->clkrate; 181 182 st_rtc_set_hw_alarm(rtc, lpa >> 32, lpa); 183 st_rtc_alarm_irq_enable(dev, t->enabled); 184 185 return 0; 186 } 187 188 static struct rtc_class_ops st_rtc_ops = { 189 .read_time = st_rtc_read_time, 190 .set_time = st_rtc_set_time, 191 .read_alarm = st_rtc_read_alarm, 192 .set_alarm = st_rtc_set_alarm, 193 .alarm_irq_enable = st_rtc_alarm_irq_enable, 194 }; 195 196 static int st_rtc_probe(struct platform_device *pdev) 197 { 198 struct device_node *np = pdev->dev.of_node; 199 struct st_rtc *rtc; 200 struct resource *res; 201 struct rtc_time tm_check; 202 uint32_t mode; 203 int ret = 0; 204 205 ret = of_property_read_u32(np, "st,lpc-mode", &mode); 206 if (ret) { 207 dev_err(&pdev->dev, "An LPC mode must be provided\n"); 208 return -EINVAL; 209 } 210 211 /* LPC can either run as a Clocksource or in RTC or WDT mode */ 212 if (mode != ST_LPC_MODE_RTC) 213 return -ENODEV; 214 215 rtc = devm_kzalloc(&pdev->dev, sizeof(struct st_rtc), GFP_KERNEL); 216 if (!rtc) 217 return -ENOMEM; 218 219 spin_lock_init(&rtc->lock); 220 221 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 222 rtc->ioaddr = devm_ioremap_resource(&pdev->dev, res); 223 if (IS_ERR(rtc->ioaddr)) 224 return PTR_ERR(rtc->ioaddr); 225 226 rtc->irq = irq_of_parse_and_map(np, 0); 227 if (!rtc->irq) { 228 dev_err(&pdev->dev, "IRQ missing or invalid\n"); 229 return -EINVAL; 230 } 231 232 ret = devm_request_irq(&pdev->dev, rtc->irq, st_rtc_handler, 0, 233 pdev->name, rtc); 234 if (ret) { 235 dev_err(&pdev->dev, "Failed to request irq %i\n", rtc->irq); 236 return ret; 237 } 238 239 enable_irq_wake(rtc->irq); 240 disable_irq(rtc->irq); 241 242 rtc->clk = clk_get(&pdev->dev, NULL); 243 if (IS_ERR(rtc->clk)) { 244 dev_err(&pdev->dev, "Unable to request clock\n"); 245 return PTR_ERR(rtc->clk); 246 } 247 248 clk_prepare_enable(rtc->clk); 249 250 rtc->clkrate = clk_get_rate(rtc->clk); 251 if (!rtc->clkrate) { 252 dev_err(&pdev->dev, "Unable to fetch clock rate\n"); 253 return -EINVAL; 254 } 255 256 device_set_wakeup_capable(&pdev->dev, 1); 257 258 platform_set_drvdata(pdev, rtc); 259 260 /* 261 * The RTC-LPC is able to manage date.year > 2038 262 * but currently the kernel can not manage this date! 263 * If the RTC-LPC has a date.year > 2038 then 264 * it's set to the epoch "Jan 1st 2000" 265 */ 266 st_rtc_read_time(&pdev->dev, &tm_check); 267 268 if (tm_check.tm_year >= (2038 - 1900)) { 269 memset(&tm_check, 0, sizeof(tm_check)); 270 tm_check.tm_year = 100; 271 tm_check.tm_mday = 1; 272 st_rtc_set_time(&pdev->dev, &tm_check); 273 } 274 275 rtc->rtc_dev = rtc_device_register("st-lpc-rtc", &pdev->dev, 276 &st_rtc_ops, THIS_MODULE); 277 if (IS_ERR(rtc->rtc_dev)) { 278 clk_disable_unprepare(rtc->clk); 279 return PTR_ERR(rtc->rtc_dev); 280 } 281 282 return 0; 283 } 284 285 static int st_rtc_remove(struct platform_device *pdev) 286 { 287 struct st_rtc *rtc = platform_get_drvdata(pdev); 288 289 if (likely(rtc->rtc_dev)) 290 rtc_device_unregister(rtc->rtc_dev); 291 292 return 0; 293 } 294 295 #ifdef CONFIG_PM_SLEEP 296 static int st_rtc_suspend(struct device *dev) 297 { 298 struct st_rtc *rtc = dev_get_drvdata(dev); 299 300 if (device_may_wakeup(dev)) 301 return 0; 302 303 writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF); 304 writel_relaxed(0, rtc->ioaddr + LPC_LPA_START_OFF); 305 writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF); 306 307 return 0; 308 } 309 310 static int st_rtc_resume(struct device *dev) 311 { 312 struct st_rtc *rtc = dev_get_drvdata(dev); 313 314 rtc_alarm_irq_enable(rtc->rtc_dev, 0); 315 316 /* 317 * clean 'rtc->alarm' to allow a new 318 * .set_alarm to the upper RTC layer 319 */ 320 memset(&rtc->alarm, 0, sizeof(struct rtc_wkalrm)); 321 322 writel_relaxed(0, rtc->ioaddr + LPC_LPA_MSB_OFF); 323 writel_relaxed(0, rtc->ioaddr + LPC_LPA_LSB_OFF); 324 writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF); 325 writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF); 326 writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF); 327 328 return 0; 329 } 330 #endif 331 332 static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume); 333 334 static const struct of_device_id st_rtc_match[] = { 335 { .compatible = "st,stih407-lpc" }, 336 {} 337 }; 338 MODULE_DEVICE_TABLE(of, st_rtc_match); 339 340 static struct platform_driver st_rtc_platform_driver = { 341 .driver = { 342 .name = "st-lpc-rtc", 343 .pm = &st_rtc_pm_ops, 344 .of_match_table = st_rtc_match, 345 }, 346 .probe = st_rtc_probe, 347 .remove = st_rtc_remove, 348 }; 349 350 module_platform_driver(st_rtc_platform_driver); 351 352 MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver"); 353 MODULE_AUTHOR("David Paris <david.paris@st.com>"); 354 MODULE_LICENSE("GPL"); 355