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