linux/drivers/rtc/rtc-coh901331.c
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   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 */
  43struct 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
  55static 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
  78static 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
  93static 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
 104static 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
 117static 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
 131static 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
 145static 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
 153static 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                clk_put(rtap->clk);
 161                platform_set_drvdata(pdev, NULL);
 162        }
 163
 164        return 0;
 165}
 166
 167
 168static int __init coh901331_probe(struct platform_device *pdev)
 169{
 170        int ret;
 171        struct coh901331_port *rtap;
 172        struct resource *res;
 173
 174        rtap = devm_kzalloc(&pdev->dev,
 175                            sizeof(struct coh901331_port), GFP_KERNEL);
 176        if (!rtap)
 177                return -ENOMEM;
 178
 179        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 180        if (!res)
 181                return -ENOENT;
 182
 183        rtap->phybase = res->start;
 184        rtap->physize = resource_size(res);
 185
 186        if (devm_request_mem_region(&pdev->dev, rtap->phybase, rtap->physize,
 187                                    "rtc-coh901331") == NULL)
 188                return -EBUSY;
 189
 190        rtap->virtbase = devm_ioremap(&pdev->dev, rtap->phybase, rtap->physize);
 191        if (!rtap->virtbase)
 192                return -ENOMEM;
 193
 194        rtap->irq = platform_get_irq(pdev, 0);
 195        if (devm_request_irq(&pdev->dev, rtap->irq, coh901331_interrupt, 0,
 196                             "RTC COH 901 331 Alarm", rtap))
 197                return -EIO;
 198
 199        rtap->clk = clk_get(&pdev->dev, NULL);
 200        if (IS_ERR(rtap->clk)) {
 201                ret = PTR_ERR(rtap->clk);
 202                dev_err(&pdev->dev, "could not get clock\n");
 203                return ret;
 204        }
 205
 206        /* We enable/disable the clock only to assure it works */
 207        ret = clk_prepare_enable(rtap->clk);
 208        if (ret) {
 209                dev_err(&pdev->dev, "could not enable clock\n");
 210                goto out_no_clk_prepenable;
 211        }
 212        clk_disable(rtap->clk);
 213
 214        platform_set_drvdata(pdev, rtap);
 215        rtap->rtc = rtc_device_register("coh901331", &pdev->dev, &coh901331_ops,
 216                                         THIS_MODULE);
 217        if (IS_ERR(rtap->rtc)) {
 218                ret = PTR_ERR(rtap->rtc);
 219                goto out_no_rtc;
 220        }
 221
 222        return 0;
 223
 224 out_no_rtc:
 225        platform_set_drvdata(pdev, NULL);
 226        clk_unprepare(rtap->clk);
 227 out_no_clk_prepenable:
 228        clk_put(rtap->clk);
 229        return ret;
 230}
 231
 232#ifdef CONFIG_PM
 233static int coh901331_suspend(struct platform_device *pdev, pm_message_t state)
 234{
 235        struct coh901331_port *rtap = dev_get_drvdata(&pdev->dev);
 236
 237        /*
 238         * If this RTC alarm will be used for waking the system up,
 239         * don't disable it of course. Else we just disable the alarm
 240         * and await suspension.
 241         */
 242        if (device_may_wakeup(&pdev->dev)) {
 243                enable_irq_wake(rtap->irq);
 244        } else {
 245                clk_enable(rtap->clk);
 246                rtap->irqmaskstore = readl(rtap->virtbase + COH901331_IRQ_MASK);
 247                writel(0, rtap->virtbase + COH901331_IRQ_MASK);
 248                clk_disable(rtap->clk);
 249        }
 250        clk_unprepare(rtap->clk);
 251        return 0;
 252}
 253
 254static int coh901331_resume(struct platform_device *pdev)
 255{
 256        struct coh901331_port *rtap = dev_get_drvdata(&pdev->dev);
 257
 258        clk_prepare(rtap->clk);
 259        if (device_may_wakeup(&pdev->dev)) {
 260                disable_irq_wake(rtap->irq);
 261        } else {
 262                clk_enable(rtap->clk);
 263                writel(rtap->irqmaskstore, rtap->virtbase + COH901331_IRQ_MASK);
 264                clk_disable(rtap->clk);
 265        }
 266        return 0;
 267}
 268#else
 269#define coh901331_suspend NULL
 270#define coh901331_resume NULL
 271#endif
 272
 273static void coh901331_shutdown(struct platform_device *pdev)
 274{
 275        struct coh901331_port *rtap = dev_get_drvdata(&pdev->dev);
 276
 277        clk_enable(rtap->clk);
 278        writel(0, rtap->virtbase + COH901331_IRQ_MASK);
 279        clk_disable_unprepare(rtap->clk);
 280}
 281
 282static struct platform_driver coh901331_driver = {
 283        .driver = {
 284                .name = "rtc-coh901331",
 285                .owner = THIS_MODULE,
 286        },
 287        .remove = __exit_p(coh901331_remove),
 288        .suspend = coh901331_suspend,
 289        .resume = coh901331_resume,
 290        .shutdown = coh901331_shutdown,
 291};
 292
 293static int __init coh901331_init(void)
 294{
 295        return platform_driver_probe(&coh901331_driver, coh901331_probe);
 296}
 297
 298static void __exit coh901331_exit(void)
 299{
 300        platform_driver_unregister(&coh901331_driver);
 301}
 302
 303module_init(coh901331_init);
 304module_exit(coh901331_exit);
 305
 306MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
 307MODULE_DESCRIPTION("ST-Ericsson AB COH 901 331 RTC Driver");
 308MODULE_LICENSE("GPL");
 309
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