kernel/drivers/rtc/rtc-at32ap700x.c

   1 /*
   2  * An RTC driver for the AVR32 AT32AP700x processor series.
   3  *
   4  * Copyright (C) 2007 Atmel Corporation
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published
   8  * by the Free Software Foundation.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/kernel.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/slab.h>
  15 #include <linux/rtc.h>
  16 #include <linux/io.h>
  17
  18 /*
  19  * This is a bare-bones RTC. It runs during most system sleep states, but has
  20  * no battery backup and gets reset during system restart.  It must be
  21  * initialized from an external clock (network, I2C, etc) before it can be of
  22  * much use.
  23  *
  24  * The alarm functionality is limited by the hardware, not supporting
  25  * periodic interrupts.
  26  */
  27
  28 #define RTC_CTRL                0x00
  29 #define RTC_CTRL_EN                0
  30 #define RTC_CTRL_PCLR              1
  31 #define RTC_CTRL_TOPEN             2
  32 #define RTC_CTRL_PSEL              8
  33
  34 #define RTC_VAL                 0x04
  35
  36 #define RTC_TOP                 0x08
  37
  38 #define RTC_IER                 0x10
  39 #define RTC_IER_TOPI               0
  40
  41 #define RTC_IDR                 0x14
  42 #define RTC_IDR_TOPI               0
  43
  44 #define RTC_IMR                 0x18
  45 #define RTC_IMR_TOPI               0
  46
  47 #define RTC_ISR                 0x1c
  48 #define RTC_ISR_TOPI               0
  49
  50 #define RTC_ICR                 0x20
  51 #define RTC_ICR_TOPI               0
  52
  53 #define RTC_BIT(name)           (1 << RTC_##name)
  54 #define RTC_BF(name, value)     ((value) << RTC_##name)
  55
  56 #define rtc_readl(dev, reg)                             \
  57         __raw_readl((dev)->regs + RTC_##reg)
  58 #define rtc_writel(dev, reg, value)                     \
  59         __raw_writel((value), (dev)->regs + RTC_##reg)
  60
  61 struct rtc_at32ap700x {
  62         struct rtc_device       *rtc;
  63         void __iomem            *regs;
  64         unsigned long           alarm_time;
  65         unsigned long           irq;
  66         /* Protect against concurrent register access. */
  67         spinlock_t              lock;
  68 };
  69
  70 static int at32_rtc_readtime(struct device *dev, struct rtc_time *tm)
  71 {
  72         struct rtc_at32ap700x *rtc = dev_get_drvdata(dev);
  73         unsigned long now;
  74
  75         now = rtc_readl(rtc, VAL);
  76         rtc_time_to_tm(now, tm);
  77
  78         return 0;
  79 }
  80
  81 static int at32_rtc_settime(struct device *dev, struct rtc_time *tm)
  82 {
  83         struct rtc_at32ap700x *rtc = dev_get_drvdata(dev);
  84         unsigned long now;
  85         int ret;
  86
  87         ret = rtc_tm_to_time(tm, &now);
  88         if (ret == 0)
  89                 rtc_writel(rtc, VAL, now);
  90
  91         return ret;
  92 }
  93
  94 static int at32_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
  95 {
  96         struct rtc_at32ap700x *rtc = dev_get_drvdata(dev);
  97
  98         spin_lock_irq(&rtc->lock);
  99         rtc_time_to_tm(rtc->alarm_time, &alrm->time);
 100         alrm->enabled = rtc_readl(rtc, IMR) & RTC_BIT(IMR_TOPI) ? 1 : 0;
 101         alrm->pending = rtc_readl(rtc, ISR) & RTC_BIT(ISR_TOPI) ? 1 : 0;
 102         spin_unlock_irq(&rtc->lock);
 103
 104         return 0;
 105 }
 106
 107 static int at32_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
 108 {
 109         struct rtc_at32ap700x *rtc = dev_get_drvdata(dev);
 110         unsigned long rtc_unix_time;
 111         unsigned long alarm_unix_time;
 112         int ret;
 113
 114         rtc_unix_time = rtc_readl(rtc, VAL);
 115
 116         ret = rtc_tm_to_time(&alrm->time, &alarm_unix_time);
 117         if (ret)
 118                 return ret;
 119
 120         if (alarm_unix_time < rtc_unix_time)
 121                 return -EINVAL;
 122
 123         spin_lock_irq(&rtc->lock);
 124         rtc->alarm_time = alarm_unix_time;
 125         rtc_writel(rtc, TOP, rtc->alarm_time);
 126         if (alrm->enabled)
 127                 rtc_writel(rtc, CTRL, rtc_readl(rtc, CTRL)
 128                                 | RTC_BIT(CTRL_TOPEN));
 129         else
 130                 rtc_writel(rtc, CTRL, rtc_readl(rtc, CTRL)
 131                                 & ~RTC_BIT(CTRL_TOPEN));
 132         spin_unlock_irq(&rtc->lock);
 133
 134         return ret;
 135 }
 136
 137 static int at32_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 138 {
 139         struct rtc_at32ap700x *rtc = dev_get_drvdata(dev);
 140         int ret = 0;
 141
 142         spin_lock_irq(&rtc->lock);
 143
 144         if (enabled) {
 145                 if (rtc_readl(rtc, VAL) > rtc->alarm_time) {
 146                         ret = -EINVAL;
 147                         goto out;
 148                 }
 149                 rtc_writel(rtc, CTRL, rtc_readl(rtc, CTRL)
 150                                 | RTC_BIT(CTRL_TOPEN));
 151                 rtc_writel(rtc, ICR, RTC_BIT(ICR_TOPI));
 152                 rtc_writel(rtc, IER, RTC_BIT(IER_TOPI));
 153         } else {
 154                 rtc_writel(rtc, CTRL, rtc_readl(rtc, CTRL)
 155                                 & ~RTC_BIT(CTRL_TOPEN));
 156                 rtc_writel(rtc, IDR, RTC_BIT(IDR_TOPI));
 157                 rtc_writel(rtc, ICR, RTC_BIT(ICR_TOPI));
 158         }
 159 out:
 160         spin_unlock_irq(&rtc->lock);
 161
 162         return ret;
 163 }
 164
 165 static irqreturn_t at32_rtc_interrupt(int irq, void *dev_id)
 166 {
 167         struct rtc_at32ap700x *rtc = (struct rtc_at32ap700x *)dev_id;
 168         unsigned long isr = rtc_readl(rtc, ISR);
 169         unsigned long events = 0;
 170         int ret = IRQ_NONE;
 171
 172         spin_lock(&rtc->lock);
 173
 174         if (isr & RTC_BIT(ISR_TOPI)) {
 175                 rtc_writel(rtc, ICR, RTC_BIT(ICR_TOPI));
 176                 rtc_writel(rtc, IDR, RTC_BIT(IDR_TOPI));
 177                 rtc_writel(rtc, CTRL, rtc_readl(rtc, CTRL)
 178                                 & ~RTC_BIT(CTRL_TOPEN));
 179                 rtc_writel(rtc, VAL, rtc->alarm_time);
 180                 events = RTC_AF | RTC_IRQF;
 181                 rtc_update_irq(rtc->rtc, 1, events);
 182                 ret = IRQ_HANDLED;
 183         }
 184
 185         spin_unlock(&rtc->lock);
 186
 187         return ret;
 188 }
 189
 190 static struct rtc_class_ops at32_rtc_ops = {
 191         .read_time      = at32_rtc_readtime,
 192         .set_time       = at32_rtc_settime,
 193         .read_alarm     = at32_rtc_readalarm,
 194         .set_alarm      = at32_rtc_setalarm,
 195         .alarm_irq_enable = at32_rtc_alarm_irq_enable,
 196 };
 197
 198 static int __init at32_rtc_probe(struct platform_device *pdev)
 199 {
 200         struct resource *regs;
 201         struct rtc_at32ap700x *rtc;
 202         int irq;
 203         int ret;
 204
 205         rtc = devm_kzalloc(&pdev->dev, sizeof(struct rtc_at32ap700x),
 206                            GFP_KERNEL);
 207         if (!rtc)
 208                 return -ENOMEM;
 209
 210         regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 211         if (!regs) {
 212                 dev_dbg(&pdev->dev, "no mmio resource defined\n");
 213                 return -ENXIO;
 214         }
 215
 216         irq = platform_get_irq(pdev, 0);
 217         if (irq <= 0) {
 218                 dev_dbg(&pdev->dev, "could not get irq\n");
 219                 return -ENXIO;
 220         }
 221
 222         rtc->irq = irq;
 223         rtc->regs = devm_ioremap(&pdev->dev, regs->start, resource_size(regs));
 224         if (!rtc->regs) {
 225                 dev_dbg(&pdev->dev, "could not map I/O memory\n");
 226                 return -ENOMEM;
 227         }
 228         spin_lock_init(&rtc->lock);
 229
 230         /*
 231          * Maybe init RTC: count from zero at 1 Hz, disable wrap irq.
 232          *
 233          * Do not reset VAL register, as it can hold an old time
 234          * from last JTAG reset.
 235          */
 236         if (!(rtc_readl(rtc, CTRL) & RTC_BIT(CTRL_EN))) {
 237                 rtc_writel(rtc, CTRL, RTC_BIT(CTRL_PCLR));
 238                 rtc_writel(rtc, IDR, RTC_BIT(IDR_TOPI));
 239                 rtc_writel(rtc, CTRL, RTC_BF(CTRL_PSEL, 0xe)
 240                                 | RTC_BIT(CTRL_EN));
 241         }
 242
 243         ret = devm_request_irq(&pdev->dev, irq, at32_rtc_interrupt, IRQF_SHARED,
 244                                 "rtc", rtc);
 245         if (ret) {
 246                 dev_dbg(&pdev->dev, "could not request irq %d\n", irq);
 247                 return ret;
 248         }
 249
 250         platform_set_drvdata(pdev, rtc);
 251
 252         rtc->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
 253                                 &at32_rtc_ops, THIS_MODULE);
 254         if (IS_ERR(rtc->rtc)) {
 255                 dev_dbg(&pdev->dev, "could not register rtc device\n");
 256                 return PTR_ERR(rtc->rtc);
 257         }
 258
 259         device_init_wakeup(&pdev->dev, 1);
 260
 261         dev_info(&pdev->dev, "Atmel RTC for AT32AP700x at %08lx irq %ld\n",
 262                         (unsigned long)rtc->regs, rtc->irq);
 263
 264         return 0;
 265 }
 266
 267 static int __exit at32_rtc_remove(struct platform_device *pdev)
 268 {
 269         device_init_wakeup(&pdev->dev, 0);
 270
 271         return 0;
 272 }
 273
 274 MODULE_ALIAS("platform:at32ap700x_rtc");
 275
 276 static struct platform_driver at32_rtc_driver = {
 277         .remove         = __exit_p(at32_rtc_remove),
 278         .driver         = {
 279                 .name   = "at32ap700x_rtc",
 280         },
 281 };
 282
 283 module_platform_driver_probe(at32_rtc_driver, at32_rtc_probe);
 284
 285 MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
 286 MODULE_DESCRIPTION("Real time clock for AVR32 AT32AP700x");
 287 MODULE_LICENSE("GPL");