drivers/rtc/rtc-digicolor.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Real Time Clock driver for Conexant Digicolor
   4  *
   5  * Copyright (C) 2015 Paradox Innovation Ltd.
   6  *
   7  * Author: Baruch Siach <baruch@tkos.co.il>
   8  */
   9
  10 #include <linux/io.h>
  11 #include <linux/iopoll.h>
  12 #include <linux/delay.h>
  13 #include <linux/module.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/rtc.h>
  16 #include <linux/of.h>
  17
  18 #define DC_RTC_CONTROL          0x0
  19 #define DC_RTC_TIME             0x8
  20 #define DC_RTC_REFERENCE        0xc
  21 #define DC_RTC_ALARM            0x10
  22 #define DC_RTC_INTFLAG_CLEAR    0x14
  23 #define DC_RTC_INTENABLE        0x16
  24
  25 #define DC_RTC_CMD_MASK         0xf
  26 #define DC_RTC_GO_BUSY          BIT(7)
  27
  28 #define CMD_NOP                 0
  29 #define CMD_RESET               1
  30 #define CMD_WRITE               3
  31 #define CMD_READ                4
  32
  33 #define CMD_DELAY_US            (10*1000)
  34 #define CMD_TIMEOUT_US          (500*CMD_DELAY_US)
  35
  36 struct dc_rtc {
  37         struct rtc_device       *rtc_dev;
  38         void __iomem            *regs;
  39 };
  40
  41 static int dc_rtc_cmds(struct dc_rtc *rtc, const u8 *cmds, int len)
  42 {
  43         u8 val;
  44         int i, ret;
  45
  46         for (i = 0; i < len; i++) {
  47                 writeb_relaxed((cmds[i] & DC_RTC_CMD_MASK) | DC_RTC_GO_BUSY,
  48                                rtc->regs + DC_RTC_CONTROL);
  49                 ret = readb_relaxed_poll_timeout(
  50                         rtc->regs + DC_RTC_CONTROL, val,
  51                         !(val & DC_RTC_GO_BUSY), CMD_DELAY_US, CMD_TIMEOUT_US);
  52                 if (ret < 0)
  53                         return ret;
  54         }
  55
  56         return 0;
  57 }
  58
  59 static int dc_rtc_read(struct dc_rtc *rtc, unsigned long *val)
  60 {
  61         static const u8 read_cmds[] = {CMD_READ, CMD_NOP};
  62         u32 reference, time1, time2;
  63         int ret;
  64
  65         ret = dc_rtc_cmds(rtc, read_cmds, ARRAY_SIZE(read_cmds));
  66         if (ret < 0)
  67                 return ret;
  68
  69         reference = readl_relaxed(rtc->regs + DC_RTC_REFERENCE);
  70         time1 = readl_relaxed(rtc->regs + DC_RTC_TIME);
  71         /* Read twice to ensure consistency */
  72         while (1) {
  73                 time2 = readl_relaxed(rtc->regs + DC_RTC_TIME);
  74                 if (time1 == time2)
  75                         break;
  76                 time1 = time2;
  77         }
  78
  79         *val = reference + time1;
  80         return 0;
  81 }
  82
  83 static int dc_rtc_write(struct dc_rtc *rtc, u32 val)
  84 {
  85         static const u8 write_cmds[] = {CMD_WRITE, CMD_NOP, CMD_RESET, CMD_NOP};
  86
  87         writel_relaxed(val, rtc->regs + DC_RTC_REFERENCE);
  88         return dc_rtc_cmds(rtc, write_cmds, ARRAY_SIZE(write_cmds));
  89 }
  90
  91 static int dc_rtc_read_time(struct device *dev, struct rtc_time *tm)
  92 {
  93         struct dc_rtc *rtc = dev_get_drvdata(dev);
  94         unsigned long now;
  95         int ret;
  96
  97         ret = dc_rtc_read(rtc, &now);
  98         if (ret < 0)
  99                 return ret;
 100         rtc_time64_to_tm(now, tm);
 101
 102         return 0;
 103 }
 104
 105 static int dc_rtc_set_time(struct device *dev, struct rtc_time *tm)
 106 {
 107         struct dc_rtc *rtc = dev_get_drvdata(dev);
 108
 109         return dc_rtc_write(rtc, rtc_tm_to_time64(tm));
 110 }
 111
 112 static int dc_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 113 {
 114         struct dc_rtc *rtc = dev_get_drvdata(dev);
 115         u32 alarm_reg, reference;
 116         unsigned long now;
 117         int ret;
 118
 119         alarm_reg = readl_relaxed(rtc->regs + DC_RTC_ALARM);
 120         reference = readl_relaxed(rtc->regs + DC_RTC_REFERENCE);
 121         rtc_time64_to_tm(reference + alarm_reg, &alarm->time);
 122
 123         ret = dc_rtc_read(rtc, &now);
 124         if (ret < 0)
 125                 return ret;
 126
 127         alarm->pending = alarm_reg + reference > now;
 128         alarm->enabled = readl_relaxed(rtc->regs + DC_RTC_INTENABLE);
 129
 130         return 0;
 131 }
 132
 133 static int dc_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 134 {
 135         struct dc_rtc *rtc = dev_get_drvdata(dev);
 136         time64_t alarm_time;
 137         u32 reference;
 138
 139         alarm_time = rtc_tm_to_time64(&alarm->time);
 140
 141         reference = readl_relaxed(rtc->regs + DC_RTC_REFERENCE);
 142         writel_relaxed(alarm_time - reference, rtc->regs + DC_RTC_ALARM);
 143
 144         writeb_relaxed(!!alarm->enabled, rtc->regs + DC_RTC_INTENABLE);
 145
 146         return 0;
 147 }
 148
 149 static int dc_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 150 {
 151         struct dc_rtc *rtc = dev_get_drvdata(dev);
 152
 153         writeb_relaxed(!!enabled, rtc->regs + DC_RTC_INTENABLE);
 154
 155         return 0;
 156 }
 157
 158 static const struct rtc_class_ops dc_rtc_ops = {
 159         .read_time              = dc_rtc_read_time,
 160         .set_time               = dc_rtc_set_time,
 161         .read_alarm             = dc_rtc_read_alarm,
 162         .set_alarm              = dc_rtc_set_alarm,
 163         .alarm_irq_enable       = dc_rtc_alarm_irq_enable,
 164 };
 165
 166 static irqreturn_t dc_rtc_irq(int irq, void *dev_id)
 167 {
 168         struct dc_rtc *rtc = dev_id;
 169
 170         writeb_relaxed(1, rtc->regs + DC_RTC_INTFLAG_CLEAR);
 171         rtc_update_irq(rtc->rtc_dev, 1, RTC_AF | RTC_IRQF);
 172
 173         return IRQ_HANDLED;
 174 }
 175
 176 static int __init dc_rtc_probe(struct platform_device *pdev)
 177 {
 178         struct dc_rtc *rtc;
 179         int irq, ret;
 180
 181         rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
 182         if (!rtc)
 183                 return -ENOMEM;
 184
 185         rtc->regs = devm_platform_ioremap_resource(pdev, 0);
 186         if (IS_ERR(rtc->regs))
 187                 return PTR_ERR(rtc->regs);
 188
 189         rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
 190         if (IS_ERR(rtc->rtc_dev))
 191                 return PTR_ERR(rtc->rtc_dev);
 192
 193         irq = platform_get_irq(pdev, 0);
 194         if (irq < 0)
 195                 return irq;
 196         ret = devm_request_irq(&pdev->dev, irq, dc_rtc_irq, 0, pdev->name, rtc);
 197         if (ret < 0)
 198                 return ret;
 199
 200         platform_set_drvdata(pdev, rtc);
 201
 202         rtc->rtc_dev->ops = &dc_rtc_ops;
 203         rtc->rtc_dev->range_max = U32_MAX;
 204
 205         return rtc_register_device(rtc->rtc_dev);
 206 }
 207
 208 static const struct of_device_id dc_dt_ids[] = {
 209         { .compatible = "cnxt,cx92755-rtc" },
 210         { /* sentinel */ }
 211 };
 212 MODULE_DEVICE_TABLE(of, dc_dt_ids);
 213
 214 static struct platform_driver dc_rtc_driver = {
 215         .driver = {
 216                 .name = "digicolor_rtc",
 217                 .of_match_table = of_match_ptr(dc_dt_ids),
 218         },
 219 };
 220 module_platform_driver_probe(dc_rtc_driver, dc_rtc_probe);
 221
 222 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
 223 MODULE_DESCRIPTION("Conexant Digicolor Realtime Clock Driver (RTC)");
 224 MODULE_LICENSE("GPL");