225 lines
5.2 KiB
C
225 lines
5.2 KiB
C
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// SPDX-License-Identifier: GPL-2.0+
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/*
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* Real Time Clock driver for Conexant Digicolor
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*
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* Copyright (C) 2015 Paradox Innovation Ltd.
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*
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* Author: Baruch Siach <baruch@tkos.co.il>
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*/
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#include <linux/io.h>
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#include <linux/iopoll.h>
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#include <linux/delay.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/rtc.h>
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#include <linux/of.h>
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#define DC_RTC_CONTROL 0x0
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#define DC_RTC_TIME 0x8
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#define DC_RTC_REFERENCE 0xc
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#define DC_RTC_ALARM 0x10
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#define DC_RTC_INTFLAG_CLEAR 0x14
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#define DC_RTC_INTENABLE 0x16
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#define DC_RTC_CMD_MASK 0xf
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#define DC_RTC_GO_BUSY BIT(7)
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#define CMD_NOP 0
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#define CMD_RESET 1
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#define CMD_WRITE 3
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#define CMD_READ 4
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#define CMD_DELAY_US (10*1000)
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#define CMD_TIMEOUT_US (500*CMD_DELAY_US)
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struct dc_rtc {
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struct rtc_device *rtc_dev;
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void __iomem *regs;
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};
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static int dc_rtc_cmds(struct dc_rtc *rtc, const u8 *cmds, int len)
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{
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u8 val;
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int i, ret;
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for (i = 0; i < len; i++) {
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writeb_relaxed((cmds[i] & DC_RTC_CMD_MASK) | DC_RTC_GO_BUSY,
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rtc->regs + DC_RTC_CONTROL);
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ret = readb_relaxed_poll_timeout(
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rtc->regs + DC_RTC_CONTROL, val,
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!(val & DC_RTC_GO_BUSY), CMD_DELAY_US, CMD_TIMEOUT_US);
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if (ret < 0)
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return ret;
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}
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return 0;
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}
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static int dc_rtc_read(struct dc_rtc *rtc, unsigned long *val)
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{
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static const u8 read_cmds[] = {CMD_READ, CMD_NOP};
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u32 reference, time1, time2;
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int ret;
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ret = dc_rtc_cmds(rtc, read_cmds, ARRAY_SIZE(read_cmds));
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if (ret < 0)
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return ret;
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reference = readl_relaxed(rtc->regs + DC_RTC_REFERENCE);
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time1 = readl_relaxed(rtc->regs + DC_RTC_TIME);
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/* Read twice to ensure consistency */
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while (1) {
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time2 = readl_relaxed(rtc->regs + DC_RTC_TIME);
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if (time1 == time2)
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break;
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time1 = time2;
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}
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*val = reference + time1;
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return 0;
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}
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static int dc_rtc_write(struct dc_rtc *rtc, u32 val)
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{
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static const u8 write_cmds[] = {CMD_WRITE, CMD_NOP, CMD_RESET, CMD_NOP};
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writel_relaxed(val, rtc->regs + DC_RTC_REFERENCE);
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return dc_rtc_cmds(rtc, write_cmds, ARRAY_SIZE(write_cmds));
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}
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static int dc_rtc_read_time(struct device *dev, struct rtc_time *tm)
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{
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struct dc_rtc *rtc = dev_get_drvdata(dev);
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unsigned long now;
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int ret;
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ret = dc_rtc_read(rtc, &now);
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if (ret < 0)
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return ret;
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rtc_time64_to_tm(now, tm);
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return 0;
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}
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static int dc_rtc_set_time(struct device *dev, struct rtc_time *tm)
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{
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struct dc_rtc *rtc = dev_get_drvdata(dev);
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return dc_rtc_write(rtc, rtc_tm_to_time64(tm));
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}
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static int dc_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
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{
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struct dc_rtc *rtc = dev_get_drvdata(dev);
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u32 alarm_reg, reference;
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unsigned long now;
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int ret;
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alarm_reg = readl_relaxed(rtc->regs + DC_RTC_ALARM);
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reference = readl_relaxed(rtc->regs + DC_RTC_REFERENCE);
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rtc_time64_to_tm(reference + alarm_reg, &alarm->time);
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ret = dc_rtc_read(rtc, &now);
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if (ret < 0)
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return ret;
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alarm->pending = alarm_reg + reference > now;
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alarm->enabled = readl_relaxed(rtc->regs + DC_RTC_INTENABLE);
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return 0;
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}
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static int dc_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
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{
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struct dc_rtc *rtc = dev_get_drvdata(dev);
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time64_t alarm_time;
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u32 reference;
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alarm_time = rtc_tm_to_time64(&alarm->time);
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reference = readl_relaxed(rtc->regs + DC_RTC_REFERENCE);
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writel_relaxed(alarm_time - reference, rtc->regs + DC_RTC_ALARM);
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writeb_relaxed(!!alarm->enabled, rtc->regs + DC_RTC_INTENABLE);
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return 0;
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}
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static int dc_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
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{
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struct dc_rtc *rtc = dev_get_drvdata(dev);
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writeb_relaxed(!!enabled, rtc->regs + DC_RTC_INTENABLE);
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return 0;
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}
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static const struct rtc_class_ops dc_rtc_ops = {
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.read_time = dc_rtc_read_time,
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.set_time = dc_rtc_set_time,
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.read_alarm = dc_rtc_read_alarm,
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.set_alarm = dc_rtc_set_alarm,
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.alarm_irq_enable = dc_rtc_alarm_irq_enable,
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};
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static irqreturn_t dc_rtc_irq(int irq, void *dev_id)
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{
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struct dc_rtc *rtc = dev_id;
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writeb_relaxed(1, rtc->regs + DC_RTC_INTFLAG_CLEAR);
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rtc_update_irq(rtc->rtc_dev, 1, RTC_AF | RTC_IRQF);
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return IRQ_HANDLED;
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}
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static int __init dc_rtc_probe(struct platform_device *pdev)
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{
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struct dc_rtc *rtc;
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int irq, ret;
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rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
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if (!rtc)
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return -ENOMEM;
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rtc->regs = devm_platform_ioremap_resource(pdev, 0);
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if (IS_ERR(rtc->regs))
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return PTR_ERR(rtc->regs);
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rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
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if (IS_ERR(rtc->rtc_dev))
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return PTR_ERR(rtc->rtc_dev);
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irq = platform_get_irq(pdev, 0);
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if (irq < 0)
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return irq;
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ret = devm_request_irq(&pdev->dev, irq, dc_rtc_irq, 0, pdev->name, rtc);
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if (ret < 0)
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return ret;
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platform_set_drvdata(pdev, rtc);
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rtc->rtc_dev->ops = &dc_rtc_ops;
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rtc->rtc_dev->range_max = U32_MAX;
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return devm_rtc_register_device(rtc->rtc_dev);
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}
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static const __maybe_unused struct of_device_id dc_dt_ids[] = {
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{ .compatible = "cnxt,cx92755-rtc" },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, dc_dt_ids);
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static struct platform_driver dc_rtc_driver = {
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.driver = {
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.name = "digicolor_rtc",
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.of_match_table = of_match_ptr(dc_dt_ids),
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},
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};
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module_platform_driver_probe(dc_rtc_driver, dc_rtc_probe);
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MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
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MODULE_DESCRIPTION("Conexant Digicolor Realtime Clock Driver (RTC)");
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MODULE_LICENSE("GPL");
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