u-boot/drivers/watchdog/mt7620_wdt.c

143 lines
2.9 KiB
C
Raw Normal View History

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2020 MediaTek Inc.
*
* Author: Weijie Gao <weijie.gao@mediatek.com>
*
* Watchdog timer for MT7620 and earlier SoCs
*/
#include <div64.h>
#include <dm.h>
#include <reset.h>
#include <wdt.h>
#include <linux/bitops.h>
#include <linux/io.h>
struct mt7620_wdt {
void __iomem *regs;
u64 timeout;
};
#define TIMER_FREQ 40000000
#define TIMER_MASK 0xffff
#define TIMER_PRESCALE 65536
#define TIMER_LOAD 0x00
#define TIMER_CTL 0x08
#define TIMER_ENABLE BIT(7)
#define TIMER_MODE_SHIFT 4
#define TIMER_MODE_WDT 3
#define TIMER_PRESCALE_SHIFT 0
#define TIMER_PRESCALE_65536 15
static void mt7620_wdt_ping(struct mt7620_wdt *priv)
{
u64 val;
val = (TIMER_FREQ / TIMER_PRESCALE) * priv->timeout;
do_div(val, 1000);
if (val > TIMER_MASK)
val = TIMER_MASK;
writel(val, priv->regs + TIMER_LOAD);
}
static int mt7620_wdt_start(struct udevice *dev, u64 ms, ulong flags)
{
struct mt7620_wdt *priv = dev_get_priv(dev);
priv->timeout = ms;
mt7620_wdt_ping(priv);
writel(TIMER_ENABLE | (TIMER_MODE_WDT << TIMER_MODE_SHIFT) |
(TIMER_PRESCALE_65536 << TIMER_PRESCALE_SHIFT),
priv->regs + TIMER_CTL);
return 0;
}
static int mt7620_wdt_stop(struct udevice *dev)
{
struct mt7620_wdt *priv = dev_get_priv(dev);
mt7620_wdt_ping(priv);
clrbits_32(priv->regs + TIMER_CTL, TIMER_ENABLE);
return 0;
}
static int mt7620_wdt_reset(struct udevice *dev)
{
struct mt7620_wdt *priv = dev_get_priv(dev);
mt7620_wdt_ping(priv);
return 0;
}
static int mt7620_wdt_expire_now(struct udevice *dev, ulong flags)
{
struct mt7620_wdt *priv = dev_get_priv(dev);
mt7620_wdt_start(dev, 1, flags);
/*
* 0 will disable the timer directly, a positive number must be used
* instead. Since the timer is a countdown timer, 1 (tick) is used.
*
* For a timer with input clock = 40MHz, 1 timer tick is short
* enough to trigger a timeout immediately.
*
* Restore prescale to 1, and load timer with 1 to trigger timeout.
*/
writel(TIMER_ENABLE | (TIMER_MODE_WDT << TIMER_MODE_SHIFT),
priv->regs + TIMER_CTL);
writel(1, priv->regs + TIMER_LOAD);
return 0;
}
static int mt7620_wdt_probe(struct udevice *dev)
{
struct mt7620_wdt *priv = dev_get_priv(dev);
struct reset_ctl reset_wdt;
int ret;
ret = reset_get_by_index(dev, 0, &reset_wdt);
if (!ret)
reset_deassert(&reset_wdt);
priv->regs = dev_remap_addr(dev);
if (!priv->regs)
return -EINVAL;
mt7620_wdt_stop(dev);
return 0;
}
static const struct wdt_ops mt7620_wdt_ops = {
.start = mt7620_wdt_start,
.reset = mt7620_wdt_reset,
.stop = mt7620_wdt_stop,
.expire_now = mt7620_wdt_expire_now,
};
static const struct udevice_id mt7620_wdt_ids[] = {
{ .compatible = "mediatek,mt7620-wdt" },
{}
};
U_BOOT_DRIVER(mt7620_wdt) = {
.name = "mt7620_wdt",
.id = UCLASS_WDT,
.of_match = mt7620_wdt_ids,
.probe = mt7620_wdt_probe,
.priv_auto = sizeof(struct mt7620_wdt),
.ops = &mt7620_wdt_ops,
};