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