stm32mp_wdt.c
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// SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
/*
* Copyright (C) 2019, STMicroelectronics - All Rights Reserved
*/
#include <common.h>
#include <clk.h>
#include <dm.h>
#include <syscon.h>
#include <wdt.h>
#include <asm/io.h>
#include <linux/iopoll.h>
/* IWDG registers */
#define IWDG_KR 0x00 /* Key register */
#define IWDG_PR 0x04 /* Prescaler Register */
#define IWDG_RLR 0x08 /* ReLoad Register */
#define IWDG_SR 0x0C /* Status Register */
/* IWDG_KR register bit mask */
#define KR_KEY_RELOAD 0xAAAA /* Reload counter enable */
#define KR_KEY_ENABLE 0xCCCC /* Peripheral enable */
#define KR_KEY_EWA 0x5555 /* Write access enable */
/* IWDG_PR register bit values */
#define PR_256 0x06 /* Prescaler set to 256 */
/* IWDG_RLR register values */
#define RLR_MAX 0xFFF /* Max value supported by reload register */
/* IWDG_SR register bit values */
#define SR_PVU BIT(0) /* Watchdog prescaler value update */
#define SR_RVU BIT(1) /* Watchdog counter reload value update */
struct stm32mp_wdt_priv {
fdt_addr_t base; /* registers addr in physical memory */
unsigned long wdt_clk_rate; /* Watchdog dedicated clock rate */
};
static int stm32mp_wdt_reset(struct udevice *dev)
{
struct stm32mp_wdt_priv *priv = dev_get_priv(dev);
writel(KR_KEY_RELOAD, priv->base + IWDG_KR);
return 0;
}
static int stm32mp_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
{
struct stm32mp_wdt_priv *priv = dev_get_priv(dev);
int reload;
u32 val;
int ret;
/* Prescaler fixed to 256 */
reload = timeout_ms * priv->wdt_clk_rate / 256;
if (reload > RLR_MAX + 1)
/* Force to max watchdog counter reload value */
reload = RLR_MAX + 1;
else if (!reload)
/* Force to min watchdog counter reload value */
reload = priv->wdt_clk_rate / 256;
/* Set prescaler & reload registers */
writel(KR_KEY_EWA, priv->base + IWDG_KR);
writel(PR_256, priv->base + IWDG_PR);
writel(reload - 1, priv->base + IWDG_RLR);
/* Enable watchdog */
writel(KR_KEY_ENABLE, priv->base + IWDG_KR);
/* Wait for the registers to be updated */
ret = readl_poll_timeout(priv->base + IWDG_SR, val,
val & (SR_PVU | SR_RVU), CONFIG_SYS_HZ);
if (ret < 0) {
pr_err("Updating IWDG registers timeout");
return -ETIMEDOUT;
}
return 0;
}
static int stm32mp_wdt_probe(struct udevice *dev)
{
struct stm32mp_wdt_priv *priv = dev_get_priv(dev);
struct clk clk;
int ret;
debug("IWDG init\n");
priv->base = devfdt_get_addr(dev);
if (priv->base == FDT_ADDR_T_NONE)
return -EINVAL;
/* Enable clock */
ret = clk_get_by_name(dev, "pclk", &clk);
if (ret)
return ret;
ret = clk_enable(&clk);
if (ret)
return ret;
/* Get LSI clock */
ret = clk_get_by_name(dev, "lsi", &clk);
if (ret)
return ret;
priv->wdt_clk_rate = clk_get_rate(&clk);
debug("IWDG init done\n");
return 0;
}
static const struct wdt_ops stm32mp_wdt_ops = {
.start = stm32mp_wdt_start,
.reset = stm32mp_wdt_reset,
};
static const struct udevice_id stm32mp_wdt_match[] = {
{ .compatible = "st,stm32mp1-iwdg" },
{ /* sentinel */ }
};
U_BOOT_DRIVER(stm32mp_wdt) = {
.name = "stm32mp-wdt",
.id = UCLASS_WDT,
.of_match = stm32mp_wdt_match,
.priv_auto_alloc_size = sizeof(struct stm32mp_wdt_priv),
.probe = stm32mp_wdt_probe,
.ops = &stm32mp_wdt_ops,
};