drivers/rtc/rtc-jz4740.c

   1 /*
   2  *  Copyright (C) 2009-2010, Lars-Peter Clausen <lars@metafoo.de>
   3  *       JZ4740 SoC RTC driver
   4  *
   5  *  This program is free software; you can redistribute it and/or modify it
   6  *  under  the terms of  the GNU General Public License as published by the
   7  *  Free Software Foundation;  either version 2 of the License, or (at your
   8  *  option) any later version.
   9  *
  10  *  You should have received a copy of the GNU General Public License along
  11  *  with this program; if not, write to the Free Software Foundation, Inc.,
  12  *  675 Mass Ave, Cambridge, MA 02139, USA.
  13  *
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/rtc.h>
  20 #include <linux/slab.h>
  21 #include <linux/spinlock.h>
  22
  23 #define JZ_REG_RTC_CTRL         0x00
  24 #define JZ_REG_RTC_SEC          0x04
  25 #define JZ_REG_RTC_SEC_ALARM    0x08
  26 #define JZ_REG_RTC_REGULATOR    0x0C
  27 #define JZ_REG_RTC_HIBERNATE    0x20
  28 #define JZ_REG_RTC_SCRATCHPAD   0x34
  29
  30 #define JZ_RTC_CTRL_WRDY        BIT(7)
  31 #define JZ_RTC_CTRL_1HZ         BIT(6)
  32 #define JZ_RTC_CTRL_1HZ_IRQ     BIT(5)
  33 #define JZ_RTC_CTRL_AF          BIT(4)
  34 #define JZ_RTC_CTRL_AF_IRQ      BIT(3)
  35 #define JZ_RTC_CTRL_AE          BIT(2)
  36 #define JZ_RTC_CTRL_ENABLE      BIT(0)
  37
  38 struct jz4740_rtc {
  39         struct resource *mem;
  40         void __iomem *base;
  41
  42         struct rtc_device *rtc;
  43
  44         unsigned int irq;
  45
  46         spinlock_t lock;
  47 };
  48
  49 static inline uint32_t jz4740_rtc_reg_read(struct jz4740_rtc *rtc, size_t reg)
  50 {
  51         return readl(rtc->base + reg);
  52 }
  53
  54 static int jz4740_rtc_wait_write_ready(struct jz4740_rtc *rtc)
  55 {
  56         uint32_t ctrl;
  57         int timeout = 1000;
  58
  59         do {
  60                 ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
  61         } while (!(ctrl & JZ_RTC_CTRL_WRDY) && --timeout);
  62
  63         return timeout ? 0 : -EIO;
  64 }
  65
  66 static inline int jz4740_rtc_reg_write(struct jz4740_rtc *rtc, size_t reg,
  67         uint32_t val)
  68 {
  69         int ret;
  70         ret = jz4740_rtc_wait_write_ready(rtc);
  71         if (ret == 0)
  72                 writel(val, rtc->base + reg);
  73
  74         return ret;
  75 }
  76
  77 static int jz4740_rtc_ctrl_set_bits(struct jz4740_rtc *rtc, uint32_t mask,
  78         bool set)
  79 {
  80         int ret;
  81         unsigned long flags;
  82         uint32_t ctrl;
  83
  84         spin_lock_irqsave(&rtc->lock, flags);
  85
  86         ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
  87
  88         /* Don't clear interrupt flags by accident */
  89         ctrl |= JZ_RTC_CTRL_1HZ | JZ_RTC_CTRL_AF;
  90
  91         if (set)
  92                 ctrl |= mask;
  93         else
  94                 ctrl &= ~mask;
  95
  96         ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_CTRL, ctrl);
  97
  98         spin_unlock_irqrestore(&rtc->lock, flags);
  99
 100         return ret;
 101 }
 102
 103 static int jz4740_rtc_read_time(struct device *dev, struct rtc_time *time)
 104 {
 105         struct jz4740_rtc *rtc = dev_get_drvdata(dev);
 106         uint32_t secs, secs2;
 107         int timeout = 5;
 108
 109         /* If the seconds register is read while it is updated, it can contain a
 110          * bogus value. This can be avoided by making sure that two consecutive
 111          * reads have the same value.
 112          */
 113         secs = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC);
 114         secs2 = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC);
 115
 116         while (secs != secs2 && --timeout) {
 117                 secs = secs2;
 118                 secs2 = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC);
 119         }
 120
 121         if (timeout == 0)
 122                 return -EIO;
 123
 124         rtc_time_to_tm(secs, time);
 125
 126         return rtc_valid_tm(time);
 127 }
 128
 129 static int jz4740_rtc_set_mmss(struct device *dev, unsigned long secs)
 130 {
 131         struct jz4740_rtc *rtc = dev_get_drvdata(dev);
 132
 133         return jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC, secs);
 134 }
 135
 136 static int jz4740_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 137 {
 138         struct jz4740_rtc *rtc = dev_get_drvdata(dev);
 139         uint32_t secs;
 140         uint32_t ctrl;
 141
 142         secs = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC_ALARM);
 143
 144         ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
 145
 146         alrm->enabled = !!(ctrl & JZ_RTC_CTRL_AE);
 147         alrm->pending = !!(ctrl & JZ_RTC_CTRL_AF);
 148
 149         rtc_time_to_tm(secs, &alrm->time);
 150
 151         return rtc_valid_tm(&alrm->time);
 152 }
 153
 154 static int jz4740_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 155 {
 156         int ret;
 157         struct jz4740_rtc *rtc = dev_get_drvdata(dev);
 158         unsigned long secs;
 159
 160         rtc_tm_to_time(&alrm->time, &secs);
 161
 162         ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC_ALARM, secs);
 163         if (!ret)
 164                 ret = jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_AE, alrm->enabled);
 165
 166         return ret;
 167 }
 168
 169 static int jz4740_rtc_update_irq_enable(struct device *dev, unsigned int enable)
 170 {
 171         struct jz4740_rtc *rtc = dev_get_drvdata(dev);
 172         return jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_1HZ_IRQ, enable);
 173 }
 174
 175 static int jz4740_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
 176 {
 177         struct jz4740_rtc *rtc = dev_get_drvdata(dev);
 178         return jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_AF_IRQ, enable);
 179 }
 180
 181 static struct rtc_class_ops jz4740_rtc_ops = {
 182         .read_time      = jz4740_rtc_read_time,
 183         .set_mmss       = jz4740_rtc_set_mmss,
 184         .read_alarm     = jz4740_rtc_read_alarm,
 185         .set_alarm      = jz4740_rtc_set_alarm,
 186         .update_irq_enable = jz4740_rtc_update_irq_enable,
 187         .alarm_irq_enable = jz4740_rtc_alarm_irq_enable,
 188 };
 189
 190 static irqreturn_t jz4740_rtc_irq(int irq, void *data)
 191 {
 192         struct jz4740_rtc *rtc = data;
 193         uint32_t ctrl;
 194         unsigned long events = 0;
 195
 196         ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
 197
 198         if (ctrl & JZ_RTC_CTRL_1HZ)
 199                 events |= (RTC_UF | RTC_IRQF);
 200
 201         if (ctrl & JZ_RTC_CTRL_AF)
 202                 events |= (RTC_AF | RTC_IRQF);
 203
 204         rtc_update_irq(rtc->rtc, 1, events);
 205
 206         jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_1HZ | JZ_RTC_CTRL_AF, false);
 207
 208         return IRQ_HANDLED;
 209 }
 210
 211 void jz4740_rtc_poweroff(struct device *dev)
 212 {
 213         struct jz4740_rtc *rtc = dev_get_drvdata(dev);
 214         jz4740_rtc_reg_write(rtc, JZ_REG_RTC_HIBERNATE, 1);
 215 }
 216 EXPORT_SYMBOL_GPL(jz4740_rtc_poweroff);
 217
 218 static int __devinit jz4740_rtc_probe(struct platform_device *pdev)
 219 {
 220         int ret;
 221         struct jz4740_rtc *rtc;
 222         uint32_t scratchpad;
 223
 224         rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
 225         if (!rtc)
 226                 return -ENOMEM;
 227
 228         rtc->irq = platform_get_irq(pdev, 0);
 229         if (rtc->irq < 0) {
 230                 ret = -ENOENT;
 231                 dev_err(&pdev->dev, "Failed to get platform irq\n");
 232                 goto err_free;
 233         }
 234
 235         rtc->mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 236         if (!rtc->mem) {
 237                 ret = -ENOENT;
 238                 dev_err(&pdev->dev, "Failed to get platform mmio memory\n");
 239                 goto err_free;
 240         }
 241
 242         rtc->mem = request_mem_region(rtc->mem->start, resource_size(rtc->mem),
 243                                         pdev->name);
 244         if (!rtc->mem) {
 245                 ret = -EBUSY;
 246                 dev_err(&pdev->dev, "Failed to request mmio memory region\n");
 247                 goto err_free;
 248         }
 249
 250         rtc->base = ioremap_nocache(rtc->mem->start, resource_size(rtc->mem));
 251         if (!rtc->base) {
 252                 ret = -EBUSY;
 253                 dev_err(&pdev->dev, "Failed to ioremap mmio memory\n");
 254                 goto err_release_mem_region;
 255         }
 256
 257         spin_lock_init(&rtc->lock);
 258
 259         platform_set_drvdata(pdev, rtc);
 260
 261         rtc->rtc = rtc_device_register(pdev->name, &pdev->dev, &jz4740_rtc_ops,
 262                                         THIS_MODULE);
 263         if (IS_ERR(rtc->rtc)) {
 264                 ret = PTR_ERR(rtc->rtc);
 265                 dev_err(&pdev->dev, "Failed to register rtc device: %d\n", ret);
 266                 goto err_iounmap;
 267         }
 268
 269         ret = request_irq(rtc->irq, jz4740_rtc_irq, 0,
 270                                 pdev->name, rtc);
 271         if (ret) {
 272                 dev_err(&pdev->dev, "Failed to request rtc irq: %d\n", ret);
 273                 goto err_unregister_rtc;
 274         }
 275
 276         scratchpad = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SCRATCHPAD);
 277         if (scratchpad != 0x12345678) {
 278                 ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SCRATCHPAD, 0x12345678);
 279                 ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC, 0);
 280                 if (ret) {
 281                         dev_err(&pdev->dev, "Could not write write to RTC registers\n");
 282                         goto err_free_irq;
 283                 }
 284         }
 285
 286         return 0;
 287
 288 err_free_irq:
 289         free_irq(rtc->irq, rtc);
 290 err_unregister_rtc:
 291         rtc_device_unregister(rtc->rtc);
 292 err_iounmap:
 293         platform_set_drvdata(pdev, NULL);
 294         iounmap(rtc->base);
 295 err_release_mem_region:
 296         release_mem_region(rtc->mem->start, resource_size(rtc->mem));
 297 err_free:
 298         kfree(rtc);
 299
 300         return ret;
 301 }
 302
 303 static int __devexit jz4740_rtc_remove(struct platform_device *pdev)
 304 {
 305         struct jz4740_rtc *rtc = platform_get_drvdata(pdev);
 306
 307         free_irq(rtc->irq, rtc);
 308
 309         rtc_device_unregister(rtc->rtc);
 310
 311         iounmap(rtc->base);
 312         release_mem_region(rtc->mem->start, resource_size(rtc->mem));
 313
 314         kfree(rtc);
 315
 316         platform_set_drvdata(pdev, NULL);
 317
 318         return 0;
 319 }
 320
 321 struct platform_driver jz4740_rtc_driver = {
 322         .probe = jz4740_rtc_probe,
 323         .remove = __devexit_p(jz4740_rtc_remove),
 324         .driver = {
 325                 .name = "jz4740-rtc",
 326                 .owner = THIS_MODULE,
 327         },
 328 };
 329
 330 static int __init jz4740_rtc_init(void)
 331 {
 332         return platform_driver_register(&jz4740_rtc_driver);
 333 }
 334 module_init(jz4740_rtc_init);
 335
 336 static void __exit jz4740_rtc_exit(void)
 337 {
 338         platform_driver_unregister(&jz4740_rtc_driver);
 339 }
 340 module_exit(jz4740_rtc_exit);
 341
 342 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 343 MODULE_LICENSE("GPL");
 344 MODULE_DESCRIPTION("RTC driver for the JZ4740 SoC\n");
 345 MODULE_ALIAS("platform:jz4740-rtc");