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Release 4.7 drivers/rtc/rtc-digicolor.c

Directory: drivers/rtc
/*
 * Real Time Clock driver for Conexant Digicolor
 *
 * Copyright (C) 2015 Paradox Innovation Ltd.
 *
 * Author: Baruch Siach <baruch@tkos.co.il>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 */

#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; }

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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; }

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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)); }

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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; }

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static int dc_rtc_set_mmss(struct device *dev, unsigned long secs) { struct dc_rtc *rtc = dev_get_drvdata(dev); return dc_rtc_write(rtc, secs); }

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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; }

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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; }

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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; }

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static struct rtc_class_ops dc_rtc_ops = { .read_time = dc_rtc_read_time, .set_mmss = dc_rtc_set_mmss, .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; }

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static int __init dc_rtc_probe(struct platform_device *pdev) { struct resource *res; struct dc_rtc *rtc; int irq, ret; rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL); if (!rtc) return -ENOMEM; res = platform_get_resource(pdev, IORESOURCE_MEM, 0); rtc->regs = devm_ioremap_resource(&pdev->dev, res); if (IS_ERR(rtc->regs)) return PTR_ERR(rtc->regs); 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 = devm_rtc_device_register(&pdev->dev, pdev->name, &dc_rtc_ops, THIS_MODULE); if (IS_ERR(rtc->rtc_dev)) return PTR_ERR(rtc->rtc_dev); return 0; }

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static const 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");

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Directory: drivers/rtc
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