LXR linux/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 */
  43struct 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
  53static 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
  76static 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
  91static 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
 102static 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
 115static 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
 129static 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
 143static const 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
 151static 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
 162static 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
 214static 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
 235static 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
 251static SIMPLE_DEV_PM_OPS(coh901331_pm_ops, coh901331_suspend, coh901331_resume);
 252
 253static 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
 262static const struct of_device_id coh901331_dt_match[] = {
 263        { .compatible = "stericsson,coh901331" },
 264        {},
 265};
 266MODULE_DEVICE_TABLE(of, coh901331_dt_match);
 267
 268static struct platform_driver coh901331_driver = {
 269        .driver = {
 270                .name = "rtc-coh901331",
 271                .pm = &coh901331_pm_ops,
 272                .of_match_table = coh901331_dt_match,
 273        },
 274        .remove = __exit_p(coh901331_remove),
 275        .shutdown = coh901331_shutdown,
 276};
 277
 278module_platform_driver_probe(coh901331_driver, coh901331_probe);
 279
 280MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
 281MODULE_DESCRIPTION("ST-Ericsson AB COH 901 331 RTC Driver");
 282MODULE_LICENSE("GPL");
 283