drivers/rtc/rtc-coh901331.c

   1 /*
   2  * Copyright (C) 2007-2009 ST-Ericsson AB
   3  * License terms: GNU General Public License (GPL) version 2
   4  * Real Time Clock interface for ST-Ericsson AB COH 901 331 RTC.
   5  * Author: Linus Walleij <linus.walleij@stericsson.com>
   6  * Based on rtc-pl031.c by Deepak Saxena <dsaxena@plexity.net>
   7  * Copyright 2006 (c) MontaVista Software, Inc.
   8  */
   9 #include <linux/init.h>
  10 #include <linux/module.h>
  11 #include <linux/rtc.h>
  12 #include <linux/clk.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/pm.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/io.h>
  17
  18 /*
  19  * Registers in the COH 901 331
  20  */
  21 /* Alarm value 32bit (R/W) */
  22 #define COH901331_ALARM         0x00U
  23 /* Used to set current time 32bit (R/W) */
  24 #define COH901331_SET_TIME      0x04U
  25 /* Indication if current time is valid 32bit (R/-) */
  26 #define COH901331_VALID         0x08U
  27 /* Read the current time 32bit (R/-) */
  28 #define COH901331_CUR_TIME      0x0cU
  29 /* Event register for the "alarm" interrupt */
  30 #define COH901331_IRQ_EVENT     0x10U
  31 /* Mask register for the "alarm" interrupt */
  32 #define COH901331_IRQ_MASK      0x14U
  33 /* Force register for the "alarm" interrupt */
  34 #define COH901331_IRQ_FORCE     0x18U
  35
  36 /*
  37  * Reference to RTC block clock
  38  * Notice that the frequent clk_enable()/clk_disable() on this
  39  * clock is mainly to be able to turn on/off other clocks in the
  40  * hierarchy as needed, the RTC clock is always on anyway.
  41  */
  42 struct coh901331_port {
  43         struct rtc_device *rtc;
  44         struct clk *clk;
  45         u32 phybase;
  46         u32 physize;
  47         void __iomem *virtbase;
  48         int irq;
  49 #ifdef CONFIG_PM
  50         u32 irqmaskstore;
  51 #endif
  52 };
  53
  54 static irqreturn_t coh901331_interrupt(int irq, void *data)
  55 {
  56         struct coh901331_port *rtap = data;
  57
  58         clk_enable(rtap->clk);
  59         /* Ack IRQ */
  60         writel(1, rtap->virtbase + COH901331_IRQ_EVENT);
  61         /*
  62          * Disable the interrupt. This is necessary because
  63          * the RTC lives on a lower-clocked line and will
  64          * not release the IRQ line until after a few (slower)
  65          * clock cycles. The interrupt will be re-enabled when
  66          * a new alarm is set anyway.
  67          */
  68         writel(0, rtap->virtbase + COH901331_IRQ_MASK);
  69         clk_disable(rtap->clk);
  70
  71         /* Set alarm flag */
  72         rtc_update_irq(rtap->rtc, 1, RTC_AF);
  73
  74         return IRQ_HANDLED;
  75 }
  76
  77 static int coh901331_read_time(struct device *dev, struct rtc_time *tm)
  78 {
  79         struct coh901331_port *rtap = dev_get_drvdata(dev);
  80
  81         clk_enable(rtap->clk);
  82         /* Check if the time is valid */
  83         if (readl(rtap->virtbase + COH901331_VALID)) {
  84                 rtc_time_to_tm(readl(rtap->virtbase + COH901331_CUR_TIME), tm);
  85                 clk_disable(rtap->clk);
  86                 return rtc_valid_tm(tm);
  87         }
  88         clk_disable(rtap->clk);
  89         return -EINVAL;
  90 }
  91
  92 static int coh901331_set_mmss(struct device *dev, unsigned long secs)
  93 {
  94         struct coh901331_port *rtap = dev_get_drvdata(dev);
  95
  96         clk_enable(rtap->clk);
  97         writel(secs, rtap->virtbase + COH901331_SET_TIME);
  98         clk_disable(rtap->clk);
  99
 100         return 0;
 101 }
 102
 103 static int coh901331_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 104 {
 105         struct coh901331_port *rtap = dev_get_drvdata(dev);
 106
 107         clk_enable(rtap->clk);
 108         rtc_time_to_tm(readl(rtap->virtbase + COH901331_ALARM), &alarm->time);
 109         alarm->pending = readl(rtap->virtbase + COH901331_IRQ_EVENT) & 1U;
 110         alarm->enabled = readl(rtap->virtbase + COH901331_IRQ_MASK) & 1U;
 111         clk_disable(rtap->clk);
 112
 113         return 0;
 114 }
 115
 116 static int coh901331_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 117 {
 118         struct coh901331_port *rtap = dev_get_drvdata(dev);
 119         unsigned long time;
 120
 121         rtc_tm_to_time(&alarm->time, &time);
 122         clk_enable(rtap->clk);
 123         writel(time, rtap->virtbase + COH901331_ALARM);
 124         writel(alarm->enabled, rtap->virtbase + COH901331_IRQ_MASK);
 125         clk_disable(rtap->clk);
 126
 127         return 0;
 128 }
 129
 130 static int coh901331_alarm_irq_enable(struct device *dev, unsigned int enabled)
 131 {
 132         struct coh901331_port *rtap = dev_get_drvdata(dev);
 133
 134         clk_enable(rtap->clk);
 135         if (enabled)
 136                 writel(1, rtap->virtbase + COH901331_IRQ_MASK);
 137         else
 138                 writel(0, rtap->virtbase + COH901331_IRQ_MASK);
 139         clk_disable(rtap->clk);
 140
 141         return 0;
 142 }
 143
 144 static struct rtc_class_ops coh901331_ops = {
 145         .read_time = coh901331_read_time,
 146         .set_mmss = coh901331_set_mmss,
 147         .read_alarm = coh901331_read_alarm,
 148         .set_alarm = coh901331_set_alarm,
 149         .alarm_irq_enable = coh901331_alarm_irq_enable,
 150 };
 151
 152 static int __exit coh901331_remove(struct platform_device *pdev)
 153 {
 154         struct coh901331_port *rtap = dev_get_drvdata(&pdev->dev);
 155
 156         if (rtap) {
 157                 free_irq(rtap->irq, rtap);
 158                 rtc_device_unregister(rtap->rtc);
 159                 clk_put(rtap->clk);
 160                 iounmap(rtap->virtbase);
 161                 release_mem_region(rtap->phybase, rtap->physize);
 162                 platform_set_drvdata(pdev, NULL);
 163                 kfree(rtap);
 164         }
 165
 166         return 0;
 167 }
 168
 169
 170 static int __init coh901331_probe(struct platform_device *pdev)
 171 {
 172         int ret;
 173         struct coh901331_port *rtap;
 174         struct resource *res;
 175
 176         rtap = kzalloc(sizeof(struct coh901331_port), GFP_KERNEL);
 177         if (!rtap)
 178                 return -ENOMEM;
 179
 180         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 181         if (!res) {
 182                 ret = -ENOENT;
 183                 goto out_no_resource;
 184         }
 185         rtap->phybase = res->start;
 186         rtap->physize = resource_size(res);
 187
 188         if (request_mem_region(rtap->phybase, rtap->physize,
 189                                "rtc-coh901331") == NULL) {
 190                 ret = -EBUSY;
 191                 goto out_no_memregion;
 192         }
 193
 194         rtap->virtbase = ioremap(rtap->phybase, rtap->physize);
 195         if (!rtap->virtbase) {
 196                 ret = -ENOMEM;
 197                 goto out_no_remap;
 198         }
 199
 200         rtap->irq = platform_get_irq(pdev, 0);
 201         if (request_irq(rtap->irq, coh901331_interrupt, IRQF_DISABLED,
 202                         "RTC COH 901 331 Alarm", rtap)) {
 203                 ret = -EIO;
 204                 goto out_no_irq;
 205         }
 206
 207         rtap->clk = clk_get(&pdev->dev, NULL);
 208         if (IS_ERR(rtap->clk)) {
 209                 ret = PTR_ERR(rtap->clk);
 210                 dev_err(&pdev->dev, "could not get clock\n");
 211                 goto out_no_clk;
 212         }
 213
 214         /* We enable/disable the clock only to assure it works */
 215         ret = clk_enable(rtap->clk);
 216         if (ret) {
 217                 dev_err(&pdev->dev, "could not enable clock\n");
 218                 goto out_no_clk_enable;
 219         }
 220         clk_disable(rtap->clk);
 221
 222         rtap->rtc = rtc_device_register("coh901331", &pdev->dev, &coh901331_ops,
 223                                          THIS_MODULE);
 224         if (IS_ERR(rtap->rtc)) {
 225                 ret = PTR_ERR(rtap->rtc);
 226                 goto out_no_rtc;
 227         }
 228
 229         platform_set_drvdata(pdev, rtap);
 230
 231         return 0;
 232
 233  out_no_rtc:
 234  out_no_clk_enable:
 235         clk_put(rtap->clk);
 236  out_no_clk:
 237         free_irq(rtap->irq, rtap);
 238  out_no_irq:
 239         iounmap(rtap->virtbase);
 240  out_no_remap:
 241         platform_set_drvdata(pdev, NULL);
 242  out_no_memregion:
 243         release_mem_region(rtap->phybase, SZ_4K);
 244  out_no_resource:
 245         kfree(rtap);
 246         return ret;
 247 }
 248
 249 #ifdef CONFIG_PM
 250 static int coh901331_suspend(struct platform_device *pdev, pm_message_t state)
 251 {
 252         struct coh901331_port *rtap = dev_get_drvdata(&pdev->dev);
 253
 254         /*
 255          * If this RTC alarm will be used for waking the system up,
 256          * don't disable it of course. Else we just disable the alarm
 257          * and await suspension.
 258          */
 259         if (device_may_wakeup(&pdev->dev)) {
 260                 enable_irq_wake(rtap->irq);
 261         } else {
 262                 clk_enable(rtap->clk);
 263                 rtap->irqmaskstore = readl(rtap->virtbase + COH901331_IRQ_MASK);
 264                 writel(0, rtap->virtbase + COH901331_IRQ_MASK);
 265                 clk_disable(rtap->clk);
 266         }
 267         return 0;
 268 }
 269
 270 static int coh901331_resume(struct platform_device *pdev)
 271 {
 272         struct coh901331_port *rtap = dev_get_drvdata(&pdev->dev);
 273
 274         if (device_may_wakeup(&pdev->dev)) {
 275                 disable_irq_wake(rtap->irq);
 276         } else {
 277                 clk_enable(rtap->clk);
 278                 writel(rtap->irqmaskstore, rtap->virtbase + COH901331_IRQ_MASK);
 279                 clk_disable(rtap->clk);
 280         }
 281         return 0;
 282 }
 283 #else
 284 #define coh901331_suspend NULL
 285 #define coh901331_resume NULL
 286 #endif
 287
 288 static void coh901331_shutdown(struct platform_device *pdev)
 289 {
 290         struct coh901331_port *rtap = dev_get_drvdata(&pdev->dev);
 291
 292         clk_enable(rtap->clk);
 293         writel(0, rtap->virtbase + COH901331_IRQ_MASK);
 294         clk_disable(rtap->clk);
 295 }
 296
 297 static struct platform_driver coh901331_driver = {
 298         .driver = {
 299                 .name = "rtc-coh901331",
 300                 .owner = THIS_MODULE,
 301         },
 302         .remove = __exit_p(coh901331_remove),
 303         .suspend = coh901331_suspend,
 304         .resume = coh901331_resume,
 305         .shutdown = coh901331_shutdown,
 306 };
 307
 308 static int __init coh901331_init(void)
 309 {
 310         return platform_driver_probe(&coh901331_driver, coh901331_probe);
 311 }
 312
 313 static void __exit coh901331_exit(void)
 314 {
 315         platform_driver_unregister(&coh901331_driver);
 316 }
 317
 318 module_init(coh901331_init);
 319 module_exit(coh901331_exit);
 320
 321 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
 322 MODULE_DESCRIPTION("ST-Ericsson AB COH 901 331 RTC Driver");
 323 MODULE_LICENSE("GPL");