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_SLEEP
  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                 clk_unprepare(rtap->clk);
 159                 platform_set_drvdata(pdev, NULL);
 160         }
 161
 162         return 0;
 163 }
 164
 165
 166 static int __init coh901331_probe(struct platform_device *pdev)
 167 {
 168         int ret;
 169         struct coh901331_port *rtap;
 170         struct resource *res;
 171
 172         rtap = devm_kzalloc(&pdev->dev,
 173                             sizeof(struct coh901331_port), GFP_KERNEL);
 174         if (!rtap)
 175                 return -ENOMEM;
 176
 177         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 178         if (!res)
 179                 return -ENOENT;
 180
 181         rtap->phybase = res->start;
 182         rtap->physize = resource_size(res);
 183
 184         if (devm_request_mem_region(&pdev->dev, rtap->phybase, rtap->physize,
 185                                     "rtc-coh901331") == NULL)
 186                 return -EBUSY;
 187
 188         rtap->virtbase = devm_ioremap(&pdev->dev, rtap->phybase, rtap->physize);
 189         if (!rtap->virtbase)
 190                 return -ENOMEM;
 191
 192         rtap->irq = platform_get_irq(pdev, 0);
 193         if (devm_request_irq(&pdev->dev, rtap->irq, coh901331_interrupt, 0,
 194                              "RTC COH 901 331 Alarm", rtap))
 195                 return -EIO;
 196
 197         rtap->clk = devm_clk_get(&pdev->dev, NULL);
 198         if (IS_ERR(rtap->clk)) {
 199                 ret = PTR_ERR(rtap->clk);
 200                 dev_err(&pdev->dev, "could not get clock\n");
 201                 return ret;
 202         }
 203
 204         /* We enable/disable the clock only to assure it works */
 205         ret = clk_prepare_enable(rtap->clk);
 206         if (ret) {
 207                 dev_err(&pdev->dev, "could not enable clock\n");
 208                 return ret;
 209         }
 210         clk_disable(rtap->clk);
 211
 212         platform_set_drvdata(pdev, rtap);
 213         rtap->rtc = devm_rtc_device_register(&pdev->dev, "coh901331",
 214                                         &coh901331_ops, THIS_MODULE);
 215         if (IS_ERR(rtap->rtc)) {
 216                 ret = PTR_ERR(rtap->rtc);
 217                 goto out_no_rtc;
 218         }
 219
 220         return 0;
 221
 222  out_no_rtc:
 223         platform_set_drvdata(pdev, NULL);
 224         clk_unprepare(rtap->clk);
 225         return ret;
 226 }
 227
 228 #ifdef CONFIG_PM_SLEEP
 229 static int coh901331_suspend(struct device *dev)
 230 {
 231         struct coh901331_port *rtap = dev_get_drvdata(dev);
 232
 233         /*
 234          * If this RTC alarm will be used for waking the system up,
 235          * don't disable it of course. Else we just disable the alarm
 236          * and await suspension.
 237          */
 238         if (device_may_wakeup(dev)) {
 239                 enable_irq_wake(rtap->irq);
 240         } else {
 241                 clk_enable(rtap->clk);
 242                 rtap->irqmaskstore = readl(rtap->virtbase + COH901331_IRQ_MASK);
 243                 writel(0, rtap->virtbase + COH901331_IRQ_MASK);
 244                 clk_disable(rtap->clk);
 245         }
 246         clk_unprepare(rtap->clk);
 247         return 0;
 248 }
 249
 250 static int coh901331_resume(struct device *dev)
 251 {
 252         struct coh901331_port *rtap = dev_get_drvdata(dev);
 253
 254         clk_prepare(rtap->clk);
 255         if (device_may_wakeup(dev)) {
 256                 disable_irq_wake(rtap->irq);
 257         } else {
 258                 clk_enable(rtap->clk);
 259                 writel(rtap->irqmaskstore, rtap->virtbase + COH901331_IRQ_MASK);
 260                 clk_disable(rtap->clk);
 261         }
 262         return 0;
 263 }
 264 #endif
 265
 266 static SIMPLE_DEV_PM_OPS(coh901331_pm_ops, coh901331_suspend, coh901331_resume);
 267
 268 static void coh901331_shutdown(struct platform_device *pdev)
 269 {
 270         struct coh901331_port *rtap = dev_get_drvdata(&pdev->dev);
 271
 272         clk_enable(rtap->clk);
 273         writel(0, rtap->virtbase + COH901331_IRQ_MASK);
 274         clk_disable_unprepare(rtap->clk);
 275 }
 276
 277 static struct platform_driver coh901331_driver = {
 278         .driver = {
 279                 .name = "rtc-coh901331",
 280                 .owner = THIS_MODULE,
 281                 .pm = &coh901331_pm_ops,
 282         },
 283         .remove = __exit_p(coh901331_remove),
 284         .shutdown = coh901331_shutdown,
 285 };
 286
 287 module_platform_driver_probe(coh901331_driver, coh901331_probe);
 288
 289 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
 290 MODULE_DESCRIPTION("ST-Ericsson AB COH 901 331 RTC Driver");
 291 MODULE_LICENSE("GPL");