mtk_wdt.c
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// SPDX-License-Identifier: GPL-2.0
/*
* Watchdog driver for MediaTek SoCs
*
* Copyright (C) 2018 MediaTek Inc.
* Author: Ryder Lee <ryder.lee@mediatek.com>
*/
#include <common.h>
#include <dm.h>
#include <hang.h>
#include <wdt.h>
#include <asm/io.h>
#define MTK_WDT_MODE 0x00
#define MTK_WDT_LENGTH 0x04
#define MTK_WDT_RESTART 0x08
#define MTK_WDT_STATUS 0x0c
#define MTK_WDT_INTERVAL 0x10
#define MTK_WDT_SWRST 0x14
#define MTK_WDT_REQ_MODE 0x30
#define MTK_WDT_DEBUG_CTL 0x40
#define WDT_MODE_KEY (0x22 << 24)
#define WDT_MODE_EN BIT(0)
#define WDT_MODE_EXTPOL BIT(1)
#define WDT_MODE_EXTEN BIT(2)
#define WDT_MODE_IRQ_EN BIT(3)
#define WDT_MODE_DUAL_EN BIT(6)
#define WDT_LENGTH_KEY 0x8
#define WDT_LENGTH_TIMEOUT(n) ((n) << 5)
#define WDT_RESTART_KEY 0x1971
#define WDT_SWRST_KEY 0x1209
struct mtk_wdt_priv {
void __iomem *base;
};
static int mtk_wdt_reset(struct udevice *dev)
{
struct mtk_wdt_priv *priv = dev_get_priv(dev);
/* Reload watchdog duration */
writel(WDT_RESTART_KEY, priv->base + MTK_WDT_RESTART);
return 0;
}
static int mtk_wdt_stop(struct udevice *dev)
{
struct mtk_wdt_priv *priv = dev_get_priv(dev);
clrsetbits_le32(priv->base + MTK_WDT_MODE, WDT_MODE_EN, WDT_MODE_KEY);
return 0;
}
static int mtk_wdt_expire_now(struct udevice *dev, ulong flags)
{
struct mtk_wdt_priv *priv = dev_get_priv(dev);
/* Kick watchdog to prevent counter == 0 */
writel(WDT_RESTART_KEY, priv->base + MTK_WDT_RESTART);
/* Reset */
writel(WDT_SWRST_KEY, priv->base + MTK_WDT_SWRST);
hang();
return 0;
}
static void mtk_wdt_set_timeout(struct udevice *dev, u64 timeout_ms)
{
struct mtk_wdt_priv *priv = dev_get_priv(dev);
u64 timeout_us;
u32 timeout_cc;
u32 length;
/*
* One WDT_LENGTH count is 512 ticks of the wdt clock
* Clock runs at 32768 Hz
* e.g. 15.625 ms per count (nominal)
* We want the ceiling after dividing timeout_ms by 15.625 ms
* We add 15624 prior to the divide to implement the ceiling
* We prevent over-flow by clamping the timeout_ms value here
* as the maximum WDT_LENGTH counts is 1023 -> 15.984375 sec
* We also enforce a minimum of 1 count
* Many watchdog peripherals have a self-imposed count of 1
* that is added to the register counts.
* The MediaTek docs lack details to know if this is the case here.
* So we enforce a minimum of 1 to guarantee operation.
*/
if (timeout_ms > 15984)
timeout_ms = 15984;
timeout_us = timeout_ms * 1000;
timeout_cc = (15624 + timeout_us) / 15625;
if (timeout_cc == 0)
timeout_cc = 1;
length = WDT_LENGTH_TIMEOUT(timeout_cc) | WDT_LENGTH_KEY;
writel(length, priv->base + MTK_WDT_LENGTH);
}
static int mtk_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
{
struct mtk_wdt_priv *priv = dev_get_priv(dev);
mtk_wdt_set_timeout(dev, timeout_ms);
mtk_wdt_reset(dev);
/* Enable watchdog reset signal */
setbits_le32(priv->base + MTK_WDT_MODE,
WDT_MODE_EN | WDT_MODE_KEY | WDT_MODE_EXTEN);
return 0;
}
static int mtk_wdt_probe(struct udevice *dev)
{
struct mtk_wdt_priv *priv = dev_get_priv(dev);
priv->base = dev_read_addr_ptr(dev);
if (!priv->base)
return -ENOENT;
/* Clear status */
clrsetbits_le32(priv->base + MTK_WDT_MODE,
WDT_MODE_IRQ_EN | WDT_MODE_EXTPOL, WDT_MODE_KEY);
return mtk_wdt_stop(dev);
}
static const struct wdt_ops mtk_wdt_ops = {
.start = mtk_wdt_start,
.reset = mtk_wdt_reset,
.stop = mtk_wdt_stop,
.expire_now = mtk_wdt_expire_now,
};
static const struct udevice_id mtk_wdt_ids[] = {
{ .compatible = "mediatek,wdt"},
{}
};
U_BOOT_DRIVER(mtk_wdt) = {
.name = "mtk_wdt",
.id = UCLASS_WDT,
.of_match = mtk_wdt_ids,
.priv_auto_alloc_size = sizeof(struct mtk_wdt_priv),
.probe = mtk_wdt_probe,
.ops = &mtk_wdt_ops,
.flags = DM_FLAG_PRE_RELOC,
};