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         void __iomem *virtbase;
  47         int irq;
  48 #ifdef CONFIG_PM_SLEEP
  49         u32 irqmaskstore;
  50 #endif
  51 };
  52
  53 static irqreturn_t coh901331_interrupt(int irq, void *data)
  54 {
  55         struct coh901331_port *rtap = data;
  56
  57         clk_enable(rtap->clk);
  58         /* Ack IRQ */
  59         writel(1, rtap->virtbase + COH901331_IRQ_EVENT);
  60         /*
  61          * Disable the interrupt. This is necessary because
  62          * the RTC lives on a lower-clocked line and will
  63          * not release the IRQ line until after a few (slower)
  64          * clock cycles. The interrupt will be re-enabled when
  65          * a new alarm is set anyway.
  66          */
  67         writel(0, rtap->virtbase + COH901331_IRQ_MASK);
  68         clk_disable(rtap->clk);
  69
  70         /* Set alarm flag */
  71         rtc_update_irq(rtap->rtc, 1, RTC_AF);
  72
  73         return IRQ_HANDLED;
  74 }
  75
  76 static int coh901331_read_time(struct device *dev, struct rtc_time *tm)
  77 {
  78         struct coh901331_port *rtap = dev_get_drvdata(dev);
  79
  80         clk_enable(rtap->clk);
  81         /* Check if the time is valid */
  82         if (readl(rtap->virtbase + COH901331_VALID)) {
  83                 rtc_time_to_tm(readl(rtap->virtbase + COH901331_CUR_TIME), tm);
  84                 clk_disable(rtap->clk);
  85                 return rtc_valid_tm(tm);
  86         }
  87         clk_disable(rtap->clk);
  88         return -EINVAL;
  89 }
  90
  91 static int coh901331_set_mmss(struct device *dev, unsigned long secs)
  92 {
  93         struct coh901331_port *rtap = dev_get_drvdata(dev);
  94
  95         clk_enable(rtap->clk);
  96         writel(secs, rtap->virtbase + COH901331_SET_TIME);
  97         clk_disable(rtap->clk);
  98
  99         return 0;
 100 }
 101
 102 static int coh901331_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 103 {
 104         struct coh901331_port *rtap = dev_get_drvdata(dev);
 105
 106         clk_enable(rtap->clk);
 107         rtc_time_to_tm(readl(rtap->virtbase + COH901331_ALARM), &alarm->time);
 108         alarm->pending = readl(rtap->virtbase + COH901331_IRQ_EVENT) & 1U;
 109         alarm->enabled = readl(rtap->virtbase + COH901331_IRQ_MASK) & 1U;
 110         clk_disable(rtap->clk);
 111
 112         return 0;
 113 }
 114
 115 static int coh901331_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 116 {
 117         struct coh901331_port *rtap = dev_get_drvdata(dev);
 118         unsigned long time;
 119
 120         rtc_tm_to_time(&alarm->time, &time);
 121         clk_enable(rtap->clk);
 122         writel(time, rtap->virtbase + COH901331_ALARM);
 123         writel(alarm->enabled, rtap->virtbase + COH901331_IRQ_MASK);
 124         clk_disable(rtap->clk);
 125
 126         return 0;
 127 }
 128
 129 static int coh901331_alarm_irq_enable(struct device *dev, unsigned int enabled)
 130 {
 131         struct coh901331_port *rtap = dev_get_drvdata(dev);
 132
 133         clk_enable(rtap->clk);
 134         if (enabled)
 135                 writel(1, rtap->virtbase + COH901331_IRQ_MASK);
 136         else
 137                 writel(0, rtap->virtbase + COH901331_IRQ_MASK);
 138         clk_disable(rtap->clk);
 139
 140         return 0;
 141 }
 142
 143 static struct rtc_class_ops coh901331_ops = {
 144         .read_time = coh901331_read_time,
 145         .set_mmss = coh901331_set_mmss,
 146         .read_alarm = coh901331_read_alarm,
 147         .set_alarm = coh901331_set_alarm,
 148         .alarm_irq_enable = coh901331_alarm_irq_enable,
 149 };
 150
 151 static int __exit coh901331_remove(struct platform_device *pdev)
 152 {
 153         struct coh901331_port *rtap = platform_get_drvdata(pdev);
 154
 155         if (rtap)
 156                 clk_unprepare(rtap->clk);
 157
 158         return 0;
 159 }
 160
 161
 162 static int __init coh901331_probe(struct platform_device *pdev)
 163 {
 164         int ret;
 165         struct coh901331_port *rtap;
 166         struct resource *res;
 167
 168         rtap = devm_kzalloc(&pdev->dev,
 169                             sizeof(struct coh901331_port), GFP_KERNEL);
 170         if (!rtap)
 171                 return -ENOMEM;
 172
 173         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 174         rtap->virtbase  = devm_ioremap_resource(&pdev->dev, res);
 175         if (IS_ERR(rtap->virtbase))
 176                 return PTR_ERR(rtap->virtbase);
 177
 178         rtap->irq = platform_get_irq(pdev, 0);
 179         if (devm_request_irq(&pdev->dev, rtap->irq, coh901331_interrupt, 0,
 180                              "RTC COH 901 331 Alarm", rtap))
 181                 return -EIO;
 182
 183         rtap->clk = devm_clk_get(&pdev->dev, NULL);
 184         if (IS_ERR(rtap->clk)) {
 185                 ret = PTR_ERR(rtap->clk);
 186                 dev_err(&pdev->dev, "could not get clock\n");
 187                 return ret;
 188         }
 189
 190         /* We enable/disable the clock only to assure it works */
 191         ret = clk_prepare_enable(rtap->clk);
 192         if (ret) {
 193                 dev_err(&pdev->dev, "could not enable clock\n");
 194                 return ret;
 195         }
 196         clk_disable(rtap->clk);
 197
 198         platform_set_drvdata(pdev, rtap);
 199         rtap->rtc = devm_rtc_device_register(&pdev->dev, "coh901331",
 200                                         &coh901331_ops, THIS_MODULE);
 201         if (IS_ERR(rtap->rtc)) {
 202                 ret = PTR_ERR(rtap->rtc);
 203                 goto out_no_rtc;
 204         }
 205
 206         return 0;
 207
 208  out_no_rtc:
 209         clk_unprepare(rtap->clk);
 210         return ret;
 211 }
 212
 213 #ifdef CONFIG_PM_SLEEP
 214 static int coh901331_suspend(struct device *dev)
 215 {
 216         struct coh901331_port *rtap = dev_get_drvdata(dev);
 217
 218         /*
 219          * If this RTC alarm will be used for waking the system up,
 220          * don't disable it of course. Else we just disable the alarm
 221          * and await suspension.
 222          */
 223         if (device_may_wakeup(dev)) {
 224                 enable_irq_wake(rtap->irq);
 225         } else {
 226                 clk_enable(rtap->clk);
 227                 rtap->irqmaskstore = readl(rtap->virtbase + COH901331_IRQ_MASK);
 228                 writel(0, rtap->virtbase + COH901331_IRQ_MASK);
 229                 clk_disable(rtap->clk);
 230         }
 231         clk_unprepare(rtap->clk);
 232         return 0;
 233 }
 234
 235 static int coh901331_resume(struct device *dev)
 236 {
 237         struct coh901331_port *rtap = dev_get_drvdata(dev);
 238
 239         clk_prepare(rtap->clk);
 240         if (device_may_wakeup(dev)) {
 241                 disable_irq_wake(rtap->irq);
 242         } else {
 243                 clk_enable(rtap->clk);
 244                 writel(rtap->irqmaskstore, rtap->virtbase + COH901331_IRQ_MASK);
 245                 clk_disable(rtap->clk);
 246         }
 247         return 0;
 248 }
 249 #endif
 250
 251 static SIMPLE_DEV_PM_OPS(coh901331_pm_ops, coh901331_suspend, coh901331_resume);
 252
 253 static void coh901331_shutdown(struct platform_device *pdev)
 254 {
 255         struct coh901331_port *rtap = platform_get_drvdata(pdev);
 256
 257         clk_enable(rtap->clk);
 258         writel(0, rtap->virtbase + COH901331_IRQ_MASK);
 259         clk_disable_unprepare(rtap->clk);
 260 }
 261
 262 static const struct of_device_id coh901331_dt_match[] = {
 263         { .compatible = "stericsson,coh901331" },
 264         {},
 265 };
 266
 267 static struct platform_driver coh901331_driver = {
 268         .driver = {
 269                 .name = "rtc-coh901331",
 270                 .pm = &coh901331_pm_ops,
 271                 .of_match_table = coh901331_dt_match,
 272         },
 273         .remove = __exit_p(coh901331_remove),
 274         .shutdown = coh901331_shutdown,
 275 };
 276
 277 module_platform_driver_probe(coh901331_driver, coh901331_probe);
 278
 279 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
 280 MODULE_DESCRIPTION("ST-Ericsson AB COH 901 331 RTC Driver");
 281 MODULE_LICENSE("GPL");