drivers/rtc/rtc-coh901331.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2007-2009 ST-Ericsson AB
   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                 clk_disable(rtap->clk);
  85                 return -EINVAL;
  86         }
  87
  88         rtc_time64_to_tm(readl(rtap->virtbase + COH901331_CUR_TIME), tm);
  89         clk_disable(rtap->clk);
  90         return 0;
  91 }
  92
  93 static int coh901331_set_time(struct device *dev, struct rtc_time *tm)
  94 {
  95         struct coh901331_port *rtap = dev_get_drvdata(dev);
  96
  97         clk_enable(rtap->clk);
  98         writel(rtc_tm_to_time64(tm), rtap->virtbase + COH901331_SET_TIME);
  99         clk_disable(rtap->clk);
 100
 101         return 0;
 102 }
 103
 104 static 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_time64_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
 117 static 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 =  rtc_tm_to_time64(&alarm->time);
 121
 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_time = coh901331_set_time,
 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
 168         rtap = devm_kzalloc(&pdev->dev,
 169                             sizeof(struct coh901331_port), GFP_KERNEL);
 170         if (!rtap)
 171                 return -ENOMEM;
 172
 173         rtap->virtbase  = devm_platform_ioremap_resource(pdev, 0);
 174         if (IS_ERR(rtap->virtbase))
 175                 return PTR_ERR(rtap->virtbase);
 176
 177         rtap->irq = platform_get_irq(pdev, 0);
 178         if (devm_request_irq(&pdev->dev, rtap->irq, coh901331_interrupt, 0,
 179                              "RTC COH 901 331 Alarm", rtap))
 180                 return -EIO;
 181
 182         rtap->clk = devm_clk_get(&pdev->dev, NULL);
 183         if (IS_ERR(rtap->clk)) {
 184                 ret = PTR_ERR(rtap->clk);
 185                 dev_err(&pdev->dev, "could not get clock\n");
 186                 return ret;
 187         }
 188
 189         rtap->rtc = devm_rtc_allocate_device(&pdev->dev);
 190         if (IS_ERR(rtap->rtc))
 191                 return PTR_ERR(rtap->rtc);
 192
 193         rtap->rtc->ops = &coh901331_ops;
 194         rtap->rtc->range_max = U32_MAX;
 195
 196         /* We enable/disable the clock only to assure it works */
 197         ret = clk_prepare_enable(rtap->clk);
 198         if (ret) {
 199                 dev_err(&pdev->dev, "could not enable clock\n");
 200                 return ret;
 201         }
 202         clk_disable(rtap->clk);
 203
 204         platform_set_drvdata(pdev, rtap);
 205
 206         ret = rtc_register_device(rtap->rtc);
 207         if (ret)
 208                 goto out_no_rtc;
 209
 210         return 0;
 211
 212  out_no_rtc:
 213         clk_unprepare(rtap->clk);
 214         return ret;
 215 }
 216
 217 #ifdef CONFIG_PM_SLEEP
 218 static int coh901331_suspend(struct device *dev)
 219 {
 220         struct coh901331_port *rtap = dev_get_drvdata(dev);
 221
 222         /*
 223          * If this RTC alarm will be used for waking the system up,
 224          * don't disable it of course. Else we just disable the alarm
 225          * and await suspension.
 226          */
 227         if (device_may_wakeup(dev)) {
 228                 enable_irq_wake(rtap->irq);
 229         } else {
 230                 clk_enable(rtap->clk);
 231                 rtap->irqmaskstore = readl(rtap->virtbase + COH901331_IRQ_MASK);
 232                 writel(0, rtap->virtbase + COH901331_IRQ_MASK);
 233                 clk_disable(rtap->clk);
 234         }
 235         clk_unprepare(rtap->clk);
 236         return 0;
 237 }
 238
 239 static int coh901331_resume(struct device *dev)
 240 {
 241         int ret;
 242         struct coh901331_port *rtap = dev_get_drvdata(dev);
 243
 244         ret = clk_prepare(rtap->clk);
 245         if (ret)
 246                 return ret;
 247
 248         if (device_may_wakeup(dev)) {
 249                 disable_irq_wake(rtap->irq);
 250         } else {
 251                 clk_enable(rtap->clk);
 252                 writel(rtap->irqmaskstore, rtap->virtbase + COH901331_IRQ_MASK);
 253                 clk_disable(rtap->clk);
 254         }
 255         return 0;
 256 }
 257 #endif
 258
 259 static SIMPLE_DEV_PM_OPS(coh901331_pm_ops, coh901331_suspend, coh901331_resume);
 260
 261 static void coh901331_shutdown(struct platform_device *pdev)
 262 {
 263         struct coh901331_port *rtap = platform_get_drvdata(pdev);
 264
 265         clk_enable(rtap->clk);
 266         writel(0, rtap->virtbase + COH901331_IRQ_MASK);
 267         clk_disable_unprepare(rtap->clk);
 268 }
 269
 270 static const struct of_device_id coh901331_dt_match[] = {
 271         { .compatible = "stericsson,coh901331" },
 272         {},
 273 };
 274 MODULE_DEVICE_TABLE(of, coh901331_dt_match);
 275
 276 static struct platform_driver coh901331_driver = {
 277         .driver = {
 278                 .name = "rtc-coh901331",
 279                 .pm = &coh901331_pm_ops,
 280                 .of_match_table = coh901331_dt_match,
 281         },
 282         .remove = __exit_p(coh901331_remove),
 283         .shutdown = coh901331_shutdown,
 284 };
 285
 286 module_platform_driver_probe(coh901331_driver, coh901331_probe);
 287
 288 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
 289 MODULE_DESCRIPTION("ST-Ericsson AB COH 901 331 RTC Driver");
 290 MODULE_LICENSE("GPL");