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/*
* RTC driver for the Aspeed 24xx SoCs
*
* Copyright 2015 IBM Corp.
*
* Joel Stanley <joel@jms.id.au >
*
* 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/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/io.h>
struct aspeed_rtc {
struct rtc_device *rtc_dev;
void __iomem *base;
spinlock_t lock;
};
#define RTC_TIME 0x00
#define RTC_YEAR 0x04
#define RTC_CTRL 0x10
#define RTC_UNLOCK 0x02
#define RTC_ENABLE 0x01
static int aspeed_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct aspeed_rtc *rtc = dev_get_drvdata(dev);
unsigned int cent, year, mon, day, hour, min, sec;
u32 reg1, reg2;
do {
reg2 = readl(rtc->base + RTC_YEAR);
reg1 = readl(rtc->base + RTC_TIME);
} while (reg2 != readl(rtc->base + RTC_YEAR));
day = (reg1 >> 24) & 0x1f;
hour = (reg1 >> 16) & 0x1f;
min = (reg1 >> 8) & 0x3f;
sec = (reg1 >> 0) & 0x3f;
cent = (reg2 >> 16) & 0x1f;
year = (reg2 >> 8) & 0x7f;
/* Month is 1-12 in hardware, and 0-11 in struct rtc_time, however we
* are using mktime64 which is 1-12, so no adjustment is necessary */
mon = (reg2 >> 0) & 0x0f;
rtc_time64_to_tm(mktime64(cent*100 + year, mon, day, hour, min, sec),
tm);
return 0;
}
static int aspeed_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct aspeed_rtc *rtc = dev_get_drvdata(dev);
unsigned long flags;
u32 reg1, reg2, ctrl;
int year, cent;
/* tm_year counts from 1900 */
cent = (tm->tm_year + 1900) / 100;
year = tm->tm_year % 100;
reg1 = (tm->tm_mday << 24) | (tm->tm_hour << 16) | (tm->tm_min << 8) |
tm->tm_sec;
/* Month in struct rtc_time is 0-11, but the hardware is 1-12 */
reg2 = ((cent & 0x1f) << 16) | ((year & 0x7f) << 8) |
((tm->tm_mon & 0xf) + 1);
/* TODO: Do we need to lock? */
spin_lock_irqsave(&rtc->lock, flags);
ctrl = readl(rtc->base + RTC_CTRL);
writel(ctrl | RTC_UNLOCK, rtc->base + RTC_CTRL);
writel(reg1, rtc->base + RTC_TIME);
writel(reg2, rtc->base + RTC_YEAR);
writel(ctrl, rtc->base + RTC_CTRL);
spin_unlock_irqrestore(&rtc->lock, flags);
return 0;
}
static struct rtc_class_ops aspeed_rtc_ops = {
.read_time = aspeed_rtc_read_time,
.set_time = aspeed_rtc_set_time,
};
static int aspeed_rtc_probe(struct platform_device *pdev)
{
struct resource *res;
struct aspeed_rtc *rtc;
rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
if (!rtc)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
rtc->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(rtc->base))
return PTR_ERR(rtc->base);
platform_set_drvdata(pdev, rtc);
rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, pdev->name,
&aspeed_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc->rtc_dev)) {
dev_err(&pdev->dev, "failed to register\n");
return PTR_ERR(rtc->rtc_dev);
}
spin_lock_init(&rtc->lock);
/* Enable RTC and clear the unlock bit */
writel(RTC_ENABLE, rtc->base + RTC_CTRL);
return 0;
}
#ifdef CONFIG_OF
static const struct of_device_id aspeed_rtc_of_match_table[] = {
{ .compatible = "aspeed,rtc", },
{}
};
#endif
static struct platform_driver aspeed_rtc_driver = {
.driver = {
.name = "aspeed-rtc",
.of_match_table = of_match_ptr(aspeed_rtc_of_match_table),
},
};
module_platform_driver_probe(aspeed_rtc_driver, aspeed_rtc_probe);
MODULE_DESCRIPTION("Aspeed AST24xx RTC driver");
MODULE_AUTHOR("Joel Stanley <joel@jms.id.au>");
MODULE_LICENSE("GPL");
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