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/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 */
  44struct 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
  54static 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
  77static 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
  92static 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
 103static 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
 116static 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
 130static 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
 144static 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
 152static 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
 163static 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
 215static 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
 236static 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
 252static SIMPLE_DEV_PM_OPS(coh901331_pm_ops, coh901331_suspend, coh901331_resume);
 253
 254static 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
 263static const struct of_device_id coh901331_dt_match[] = {
 264        { .compatible = "stericsson,coh901331" },
 265        {},
 266};
 267MODULE_DEVICE_TABLE(of, coh901331_dt_match);
 268
 269static 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
 279module_platform_driver_probe(coh901331_driver, coh901331_probe);
 280
 281MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
 282MODULE_DESCRIPTION("ST-Ericsson AB COH 901 331 RTC Driver");
 283MODULE_LICENSE("GPL");
 284