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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright 2023, Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
*
* This driver emulates a real time clock based on timer ticks.
*/
#include <div64.h>
#include <dm.h>
#include <mapmem.h>
#include <rtc.h>
#include <linux/io.h>
/**
* struct goldfish_rtc - private data for RTC driver
*/
struct goldfish_rtc {
/**
* @base: base address for register file
*/
void __iomem *base;
/**
* @isdst: daylight saving time
*/
int isdst;
};
/* Register offsets */
#define GOLDFISH_TIME_LOW 0x00
#define GOLDFISH_TIME_HIGH 0x04
static int goldfish_rtc_get(struct udevice *dev, struct rtc_time *time)
{
struct goldfish_rtc *priv = dev_get_priv(dev);
void __iomem *base = priv->base;
u64 time_high;
u64 time_low;
u64 now;
time_low = ioread32(base + GOLDFISH_TIME_LOW);
time_high = ioread32(base + GOLDFISH_TIME_HIGH);
now = (time_high << 32) | time_low;
do_div(now, 1000000000U);
rtc_to_tm(now, time);
time->tm_isdst = priv->isdst;
return 0;
}
static int goldfish_rtc_set(struct udevice *dev, const struct rtc_time *time)
{
struct goldfish_rtc *priv = dev_get_priv(dev);
void __iomem *base = priv->base;
u64 now;
if (time->tm_year < 1970)
return -EINVAL;
now = rtc_mktime(time) * 1000000000ULL;
iowrite32(now >> 32, base + GOLDFISH_TIME_HIGH);
iowrite32(now, base + GOLDFISH_TIME_LOW);
if (time->tm_isdst > 0)
priv->isdst = 1;
else if (time->tm_isdst < 0)
priv->isdst = -1;
else
priv->isdst = 0;
return 0;
}
static int goldfish_rtc_probe(struct udevice *dev)
{
struct goldfish_rtc *priv = dev_get_priv(dev);
fdt_addr_t addr;
addr = dev_read_addr(dev);
if (addr == FDT_ADDR_T_NONE)
return -EINVAL;
priv->base = map_sysmem(addr, 0x20);
return 0;
}
static const struct rtc_ops goldfish_rtc_ops = {
.get = goldfish_rtc_get,
.set = goldfish_rtc_set,
};
static const struct udevice_id goldfish_rtc_of_match[] = {
{ .compatible = "google,goldfish-rtc", },
{},
};
U_BOOT_DRIVER(rtc_goldfish) = {
.name = "rtc_goldfish",
.id = UCLASS_RTC,
.ops = &goldfish_rtc_ops,
.probe = goldfish_rtc_probe,
.of_match = goldfish_rtc_of_match,
.priv_auto = sizeof(struct goldfish_rtc),
};
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