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1// SPDX-License-Identifier: GPL-2.0+2/*3 * Real Time Clock driver for Conexant Digicolor4 *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 0x019#define DC_RTC_TIME 0x820#define DC_RTC_REFERENCE 0xc21#define DC_RTC_ALARM 0x1022#define DC_RTC_INTFLAG_CLEAR 0x1423#define DC_RTC_INTENABLE 0x1624 25#define DC_RTC_CMD_MASK 0xf26#define DC_RTC_GO_BUSY BIT(7)27 28#define CMD_NOP 029#define CMD_RESET 130#define CMD_WRITE 331#define CMD_READ 432 33#define CMD_DELAY_US (10*1000)34#define CMD_TIMEOUT_US (500*CMD_DELAY_US)35 36struct dc_rtc {37 struct rtc_device *rtc_dev;38 void __iomem *regs;39};40 41static 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 59static 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 83static 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 91static 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 105static 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 112static 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 133static 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 149static 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 158static 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 166static 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 176static 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 devm_rtc_register_device(rtc->rtc_dev);206}207 208static const __maybe_unused struct of_device_id dc_dt_ids[] = {209 { .compatible = "cnxt,cx92755-rtc" },210 { /* sentinel */ }211};212MODULE_DEVICE_TABLE(of, dc_dt_ids);213 214static struct platform_driver dc_rtc_driver = {215 .driver = {216 .name = "digicolor_rtc",217 .of_match_table = of_match_ptr(dc_dt_ids),218 },219};220module_platform_driver_probe(dc_rtc_driver, dc_rtc_probe);221 222MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");223MODULE_DESCRIPTION("Conexant Digicolor Realtime Clock Driver (RTC)");224MODULE_LICENSE("GPL");225