1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * A RTC driver for the Simtek STK17TA8 4 * 5 * By Thomas Hommel <thomas.hommel@ge.com> 6 * 7 * Based on the DS1553 driver from 8 * Atsushi Nemoto <anemo@mba.ocn.ne.jp> 9 */ 10 11 #include <linux/bcd.h> 12 #include <linux/init.h> 13 #include <linux/kernel.h> 14 #include <linux/gfp.h> 15 #include <linux/delay.h> 16 #include <linux/jiffies.h> 17 #include <linux/interrupt.h> 18 #include <linux/rtc.h> 19 #include <linux/platform_device.h> 20 #include <linux/io.h> 21 #include <linux/module.h> 22 23 #define RTC_REG_SIZE 0x20000 24 #define RTC_OFFSET 0x1fff0 25 26 #define RTC_FLAGS (RTC_OFFSET + 0) 27 #define RTC_CENTURY (RTC_OFFSET + 1) 28 #define RTC_SECONDS_ALARM (RTC_OFFSET + 2) 29 #define RTC_MINUTES_ALARM (RTC_OFFSET + 3) 30 #define RTC_HOURS_ALARM (RTC_OFFSET + 4) 31 #define RTC_DATE_ALARM (RTC_OFFSET + 5) 32 #define RTC_INTERRUPTS (RTC_OFFSET + 6) 33 #define RTC_WATCHDOG (RTC_OFFSET + 7) 34 #define RTC_CALIBRATION (RTC_OFFSET + 8) 35 #define RTC_SECONDS (RTC_OFFSET + 9) 36 #define RTC_MINUTES (RTC_OFFSET + 10) 37 #define RTC_HOURS (RTC_OFFSET + 11) 38 #define RTC_DAY (RTC_OFFSET + 12) 39 #define RTC_DATE (RTC_OFFSET + 13) 40 #define RTC_MONTH (RTC_OFFSET + 14) 41 #define RTC_YEAR (RTC_OFFSET + 15) 42 43 #define RTC_SECONDS_MASK 0x7f 44 #define RTC_DAY_MASK 0x07 45 #define RTC_CAL_MASK 0x3f 46 47 /* Bits in the Calibration register */ 48 #define RTC_STOP 0x80 49 50 /* Bits in the Flags register */ 51 #define RTC_FLAGS_AF 0x40 52 #define RTC_FLAGS_PF 0x20 53 #define RTC_WRITE 0x02 54 #define RTC_READ 0x01 55 56 /* Bits in the Interrupts register */ 57 #define RTC_INTS_AIE 0x40 58 59 struct rtc_plat_data { 60 struct rtc_device *rtc; 61 void __iomem *ioaddr; 62 unsigned long last_jiffies; 63 int irq; 64 unsigned int irqen; 65 int alrm_sec; 66 int alrm_min; 67 int alrm_hour; 68 int alrm_mday; 69 spinlock_t lock; 70 }; 71 72 static int stk17ta8_rtc_set_time(struct device *dev, struct rtc_time *tm) 73 { 74 struct rtc_plat_data *pdata = dev_get_drvdata(dev); 75 void __iomem *ioaddr = pdata->ioaddr; 76 u8 flags; 77 78 flags = readb(pdata->ioaddr + RTC_FLAGS); 79 writeb(flags | RTC_WRITE, pdata->ioaddr + RTC_FLAGS); 80 81 writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR); 82 writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH); 83 writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY); 84 writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE); 85 writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS); 86 writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES); 87 writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS); 88 writeb(bin2bcd((tm->tm_year + 1900) / 100), ioaddr + RTC_CENTURY); 89 90 writeb(flags & ~RTC_WRITE, pdata->ioaddr + RTC_FLAGS); 91 return 0; 92 } 93 94 static int stk17ta8_rtc_read_time(struct device *dev, struct rtc_time *tm) 95 { 96 struct rtc_plat_data *pdata = dev_get_drvdata(dev); 97 void __iomem *ioaddr = pdata->ioaddr; 98 unsigned int year, month, day, hour, minute, second, week; 99 unsigned int century; 100 u8 flags; 101 102 /* give enough time to update RTC in case of continuous read */ 103 if (pdata->last_jiffies == jiffies) 104 msleep(1); 105 pdata->last_jiffies = jiffies; 106 107 flags = readb(pdata->ioaddr + RTC_FLAGS); 108 writeb(flags | RTC_READ, ioaddr + RTC_FLAGS); 109 second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK; 110 minute = readb(ioaddr + RTC_MINUTES); 111 hour = readb(ioaddr + RTC_HOURS); 112 day = readb(ioaddr + RTC_DATE); 113 week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK; 114 month = readb(ioaddr + RTC_MONTH); 115 year = readb(ioaddr + RTC_YEAR); 116 century = readb(ioaddr + RTC_CENTURY); 117 writeb(flags & ~RTC_READ, ioaddr + RTC_FLAGS); 118 tm->tm_sec = bcd2bin(second); 119 tm->tm_min = bcd2bin(minute); 120 tm->tm_hour = bcd2bin(hour); 121 tm->tm_mday = bcd2bin(day); 122 tm->tm_wday = bcd2bin(week); 123 tm->tm_mon = bcd2bin(month) - 1; 124 /* year is 1900 + tm->tm_year */ 125 tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900; 126 127 return 0; 128 } 129 130 static void stk17ta8_rtc_update_alarm(struct rtc_plat_data *pdata) 131 { 132 void __iomem *ioaddr = pdata->ioaddr; 133 unsigned long irqflags; 134 u8 flags; 135 136 spin_lock_irqsave(&pdata->lock, irqflags); 137 138 flags = readb(ioaddr + RTC_FLAGS); 139 writeb(flags | RTC_WRITE, ioaddr + RTC_FLAGS); 140 141 writeb(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ? 142 0x80 : bin2bcd(pdata->alrm_mday), 143 ioaddr + RTC_DATE_ALARM); 144 writeb(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ? 145 0x80 : bin2bcd(pdata->alrm_hour), 146 ioaddr + RTC_HOURS_ALARM); 147 writeb(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ? 148 0x80 : bin2bcd(pdata->alrm_min), 149 ioaddr + RTC_MINUTES_ALARM); 150 writeb(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ? 151 0x80 : bin2bcd(pdata->alrm_sec), 152 ioaddr + RTC_SECONDS_ALARM); 153 writeb(pdata->irqen ? RTC_INTS_AIE : 0, ioaddr + RTC_INTERRUPTS); 154 readb(ioaddr + RTC_FLAGS); /* clear interrupts */ 155 writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS); 156 spin_unlock_irqrestore(&pdata->lock, irqflags); 157 } 158 159 static int stk17ta8_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm) 160 { 161 struct rtc_plat_data *pdata = dev_get_drvdata(dev); 162 163 if (pdata->irq <= 0) 164 return -EINVAL; 165 pdata->alrm_mday = alrm->time.tm_mday; 166 pdata->alrm_hour = alrm->time.tm_hour; 167 pdata->alrm_min = alrm->time.tm_min; 168 pdata->alrm_sec = alrm->time.tm_sec; 169 if (alrm->enabled) 170 pdata->irqen |= RTC_AF; 171 stk17ta8_rtc_update_alarm(pdata); 172 return 0; 173 } 174 175 static int stk17ta8_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm) 176 { 177 struct rtc_plat_data *pdata = dev_get_drvdata(dev); 178 179 if (pdata->irq <= 0) 180 return -EINVAL; 181 alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday; 182 alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour; 183 alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min; 184 alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec; 185 alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0; 186 return 0; 187 } 188 189 static irqreturn_t stk17ta8_rtc_interrupt(int irq, void *dev_id) 190 { 191 struct platform_device *pdev = dev_id; 192 struct rtc_plat_data *pdata = platform_get_drvdata(pdev); 193 void __iomem *ioaddr = pdata->ioaddr; 194 unsigned long events = 0; 195 196 spin_lock(&pdata->lock); 197 /* read and clear interrupt */ 198 if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_AF) { 199 events = RTC_IRQF; 200 if (readb(ioaddr + RTC_SECONDS_ALARM) & 0x80) 201 events |= RTC_UF; 202 else 203 events |= RTC_AF; 204 rtc_update_irq(pdata->rtc, 1, events); 205 } 206 spin_unlock(&pdata->lock); 207 return events ? IRQ_HANDLED : IRQ_NONE; 208 } 209 210 static int stk17ta8_rtc_alarm_irq_enable(struct device *dev, 211 unsigned int enabled) 212 { 213 struct rtc_plat_data *pdata = dev_get_drvdata(dev); 214 215 if (pdata->irq <= 0) 216 return -EINVAL; 217 if (enabled) 218 pdata->irqen |= RTC_AF; 219 else 220 pdata->irqen &= ~RTC_AF; 221 stk17ta8_rtc_update_alarm(pdata); 222 return 0; 223 } 224 225 static const struct rtc_class_ops stk17ta8_rtc_ops = { 226 .read_time = stk17ta8_rtc_read_time, 227 .set_time = stk17ta8_rtc_set_time, 228 .read_alarm = stk17ta8_rtc_read_alarm, 229 .set_alarm = stk17ta8_rtc_set_alarm, 230 .alarm_irq_enable = stk17ta8_rtc_alarm_irq_enable, 231 }; 232 233 static int stk17ta8_nvram_read(void *priv, unsigned int pos, void *val, 234 size_t bytes) 235 { 236 struct rtc_plat_data *pdata = priv; 237 void __iomem *ioaddr = pdata->ioaddr; 238 u8 *buf = val; 239 240 for (; bytes; bytes--) 241 *buf++ = readb(ioaddr + pos++); 242 return 0; 243 } 244 245 static int stk17ta8_nvram_write(void *priv, unsigned int pos, void *val, 246 size_t bytes) 247 { 248 struct rtc_plat_data *pdata = priv; 249 void __iomem *ioaddr = pdata->ioaddr; 250 u8 *buf = val; 251 252 for (; bytes; bytes--) 253 writeb(*buf++, ioaddr + pos++); 254 return 0; 255 } 256 257 static int stk17ta8_rtc_probe(struct platform_device *pdev) 258 { 259 unsigned int cal; 260 unsigned int flags; 261 struct rtc_plat_data *pdata; 262 void __iomem *ioaddr; 263 int ret = 0; 264 struct nvmem_config nvmem_cfg = { 265 .name = "stk17ta8_nvram", 266 .word_size = 1, 267 .stride = 1, 268 .size = RTC_OFFSET, 269 .reg_read = stk17ta8_nvram_read, 270 .reg_write = stk17ta8_nvram_write, 271 }; 272 273 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL); 274 if (!pdata) 275 return -ENOMEM; 276 277 ioaddr = devm_platform_ioremap_resource(pdev, 0); 278 if (IS_ERR(ioaddr)) 279 return PTR_ERR(ioaddr); 280 pdata->ioaddr = ioaddr; 281 pdata->irq = platform_get_irq(pdev, 0); 282 283 /* turn RTC on if it was not on */ 284 cal = readb(ioaddr + RTC_CALIBRATION); 285 if (cal & RTC_STOP) { 286 cal &= RTC_CAL_MASK; 287 flags = readb(ioaddr + RTC_FLAGS); 288 writeb(flags | RTC_WRITE, ioaddr + RTC_FLAGS); 289 writeb(cal, ioaddr + RTC_CALIBRATION); 290 writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS); 291 } 292 if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_PF) 293 dev_warn(&pdev->dev, "voltage-low detected.\n"); 294 295 spin_lock_init(&pdata->lock); 296 pdata->last_jiffies = jiffies; 297 platform_set_drvdata(pdev, pdata); 298 if (pdata->irq > 0) { 299 writeb(0, ioaddr + RTC_INTERRUPTS); 300 if (devm_request_irq(&pdev->dev, pdata->irq, 301 stk17ta8_rtc_interrupt, 302 IRQF_SHARED, 303 pdev->name, pdev) < 0) { 304 dev_warn(&pdev->dev, "interrupt not available.\n"); 305 pdata->irq = 0; 306 } 307 } 308 309 pdata->rtc = devm_rtc_allocate_device(&pdev->dev); 310 if (IS_ERR(pdata->rtc)) 311 return PTR_ERR(pdata->rtc); 312 313 pdata->rtc->ops = &stk17ta8_rtc_ops; 314 315 nvmem_cfg.priv = pdata; 316 ret = devm_rtc_nvmem_register(pdata->rtc, &nvmem_cfg); 317 if (ret) 318 return ret; 319 320 return devm_rtc_register_device(pdata->rtc); 321 } 322 323 /* work with hotplug and coldplug */ 324 MODULE_ALIAS("platform:stk17ta8"); 325 326 static struct platform_driver stk17ta8_rtc_driver = { 327 .probe = stk17ta8_rtc_probe, 328 .driver = { 329 .name = "stk17ta8", 330 }, 331 }; 332 333 module_platform_driver(stk17ta8_rtc_driver); 334 335 MODULE_AUTHOR("Thomas Hommel <thomas.hommel@ge.com>"); 336 MODULE_DESCRIPTION("Simtek STK17TA8 RTC driver"); 337 MODULE_LICENSE("GPL"); 338