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/mod_devicetable.h>
  12 #include <linux/rtc.h>
  13 #include <linux/clk.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/pm.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/io.h>
  18 #include <linux/slab.h>
  19
  20 /*
  21  * Registers in the COH 901 331
  22  */
  23 /* Alarm value 32bit (R/W) */
  24 #define COH901331_ALARM         0x00U
  25 /* Used to set current time 32bit (R/W) */
  26 #define COH901331_SET_TIME      0x04U
  27 /* Indication if current time is valid 32bit (R/-) */
  28 #define COH901331_VALID         0x08U
  29 /* Read the current time 32bit (R/-) */
  30 #define COH901331_CUR_TIME      0x0cU
  31 /* Event register for the "alarm" interrupt */
  32 #define COH901331_IRQ_EVENT     0x10U
  33 /* Mask register for the "alarm" interrupt */
  34 #define COH901331_IRQ_MASK      0x14U
  35 /* Force register for the "alarm" interrupt */
  36 #define COH901331_IRQ_FORCE     0x18U
  37
  38 /*
  39  * Reference to RTC block clock
  40  * Notice that the frequent clk_enable()/clk_disable() on this
  41  * clock is mainly to be able to turn on/off other clocks in the
  42  * hierarchy as needed, the RTC clock is always on anyway.
  43  */
  44 struct coh901331_port {
  45         struct rtc_device *rtc;
  46         struct clk *clk;
  47         void __iomem *virtbase;
  48         int irq;
  49 #ifdef CONFIG_PM_SLEEP
  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 0;
  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 const 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 = platform_get_drvdata(pdev);
 155
 156         if (rtap)
 157                 clk_unprepare(rtap->clk);
 158
 159         return 0;
 160 }
 161
 162
 163 static int __init coh901331_probe(struct platform_device *pdev)
 164 {
 165         int ret;
 166         struct coh901331_port *rtap;
 167         struct resource *res;
 168
 169         rtap = devm_kzalloc(&pdev->dev,
 170                             sizeof(struct coh901331_port), GFP_KERNEL);
 171         if (!rtap)
 172                 return -ENOMEM;
 173
 174         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 175         rtap->virtbase  = devm_ioremap_resource(&pdev->dev, res);
 176         if (IS_ERR(rtap->virtbase))
 177                 return PTR_ERR(rtap->virtbase);
 178
 179         rtap->irq = platform_get_irq(pdev, 0);
 180         if (devm_request_irq(&pdev->dev, rtap->irq, coh901331_interrupt, 0,
 181                              "RTC COH 901 331 Alarm", rtap))
 182                 return -EIO;
 183
 184         rtap->clk = devm_clk_get(&pdev->dev, NULL);
 185         if (IS_ERR(rtap->clk)) {
 186                 ret = PTR_ERR(rtap->clk);
 187                 dev_err(&pdev->dev, "could not get clock\n");
 188                 return ret;
 189         }
 190
 191         /* We enable/disable the clock only to assure it works */
 192         ret = clk_prepare_enable(rtap->clk);
 193         if (ret) {
 194                 dev_err(&pdev->dev, "could not enable clock\n");
 195                 return ret;
 196         }
 197         clk_disable(rtap->clk);
 198
 199         platform_set_drvdata(pdev, rtap);
 200         rtap->rtc = devm_rtc_device_register(&pdev->dev, "coh901331",
 201                                         &coh901331_ops, THIS_MODULE);
 202         if (IS_ERR(rtap->rtc)) {
 203                 ret = PTR_ERR(rtap->rtc);
 204                 goto out_no_rtc;
 205         }
 206
 207         return 0;
 208
 209  out_no_rtc:
 210         clk_unprepare(rtap->clk);
 211         return ret;
 212 }
 213
 214 #ifdef CONFIG_PM_SLEEP
 215 static int coh901331_suspend(struct device *dev)
 216 {
 217         struct coh901331_port *rtap = dev_get_drvdata(dev);
 218
 219         /*
 220          * If this RTC alarm will be used for waking the system up,
 221          * don't disable it of course. Else we just disable the alarm
 222          * and await suspension.
 223          */
 224         if (device_may_wakeup(dev)) {
 225                 enable_irq_wake(rtap->irq);
 226         } else {
 227                 clk_enable(rtap->clk);
 228                 rtap->irqmaskstore = readl(rtap->virtbase + COH901331_IRQ_MASK);
 229                 writel(0, rtap->virtbase + COH901331_IRQ_MASK);
 230                 clk_disable(rtap->clk);
 231         }
 232         clk_unprepare(rtap->clk);
 233         return 0;
 234 }
 235
 236 static int coh901331_resume(struct device *dev)
 237 {
 238         struct coh901331_port *rtap = dev_get_drvdata(dev);
 239
 240         clk_prepare(rtap->clk);
 241         if (device_may_wakeup(dev)) {
 242                 disable_irq_wake(rtap->irq);
 243         } else {
 244                 clk_enable(rtap->clk);
 245                 writel(rtap->irqmaskstore, rtap->virtbase + COH901331_IRQ_MASK);
 246                 clk_disable(rtap->clk);
 247         }
 248         return 0;
 249 }
 250 #endif
 251
 252 static SIMPLE_DEV_PM_OPS(coh901331_pm_ops, coh901331_suspend, coh901331_resume);
 253
 254 static void coh901331_shutdown(struct platform_device *pdev)
 255 {
 256         struct coh901331_port *rtap = platform_get_drvdata(pdev);
 257
 258         clk_enable(rtap->clk);
 259         writel(0, rtap->virtbase + COH901331_IRQ_MASK);
 260         clk_disable_unprepare(rtap->clk);
 261 }
 262
 263 static const struct of_device_id coh901331_dt_match[] = {
 264         { .compatible = "stericsson,coh901331" },
 265         {},
 266 };
 267 MODULE_DEVICE_TABLE(of, coh901331_dt_match);
 268
 269 static struct platform_driver coh901331_driver = {
 270         .driver = {
 271                 .name = "rtc-coh901331",
 272                 .pm = &coh901331_pm_ops,
 273                 .of_match_table = coh901331_dt_match,
 274         },
 275         .remove = __exit_p(coh901331_remove),
 276         .shutdown = coh901331_shutdown,
 277 };
 278
 279 module_platform_driver_probe(coh901331_driver, coh901331_probe);
 280
 281 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
 282 MODULE_DESCRIPTION("ST-Ericsson AB COH 901 331 RTC Driver");
 283 MODULE_LICENSE("GPL");