sp805_wdt.c
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// SPDX-License-Identifier: GPL-2.0+
/*
* Watchdog driver for SP805 on some Layerscape SoC
*
* Copyright 2019 NXP
*/
#include <asm/io.h>
#include <common.h>
#include <dm/device.h>
#include <dm/fdtaddr.h>
#include <dm/read.h>
#include <linux/bitops.h>
#include <watchdog.h>
#include <wdt.h>
#include <linux/err.h>
#define WDTLOAD 0x000
#define WDTCONTROL 0x008
#define WDTINTCLR 0x00C
#define WDTLOCK 0xC00
#define TIME_OUT_MIN_MSECS 1
#define TIME_OUT_MAX_MSECS 120000
#define SYS_FSL_WDT_CLK_DIV 16
#define INT_ENABLE BIT(0)
#define RESET_ENABLE BIT(1)
#define DISABLE 0
#define UNLOCK 0x1ACCE551
#define LOCK 0x00000001
#define INT_MASK BIT(0)
DECLARE_GLOBAL_DATA_PTR;
struct sp805_wdt_priv {
void __iomem *reg;
};
static int sp805_wdt_reset(struct udevice *dev)
{
struct sp805_wdt_priv *priv = dev_get_priv(dev);
writel(UNLOCK, priv->reg + WDTLOCK);
writel(INT_MASK, priv->reg + WDTINTCLR);
writel(LOCK, priv->reg + WDTLOCK);
readl(priv->reg + WDTLOCK);
return 0;
}
static int sp805_wdt_start(struct udevice *dev, u64 timeout, ulong flags)
{
u32 load_value;
u32 load_time;
struct sp805_wdt_priv *priv = dev_get_priv(dev);
load_time = (u32)timeout;
if (timeout < TIME_OUT_MIN_MSECS)
load_time = TIME_OUT_MIN_MSECS;
else if (timeout > TIME_OUT_MAX_MSECS)
load_time = TIME_OUT_MAX_MSECS;
/* sp805 runs counter with given value twice, so when the max timeout is
* set 120s, the gd->bus_clk is less than 1145MHz, the load_value will
* not overflow.
*/
load_value = (gd->bus_clk) /
(2 * 1000 * SYS_FSL_WDT_CLK_DIV) * load_time;
writel(UNLOCK, priv->reg + WDTLOCK);
writel(load_value, priv->reg + WDTLOAD);
writel(INT_MASK, priv->reg + WDTINTCLR);
writel(INT_ENABLE | RESET_ENABLE, priv->reg + WDTCONTROL);
writel(LOCK, priv->reg + WDTLOCK);
readl(priv->reg + WDTLOCK);
return 0;
}
static int sp805_wdt_stop(struct udevice *dev)
{
struct sp805_wdt_priv *priv = dev_get_priv(dev);
writel(UNLOCK, priv->reg + WDTLOCK);
writel(DISABLE, priv->reg + WDTCONTROL);
writel(LOCK, priv->reg + WDTLOCK);
readl(priv->reg + WDTLOCK);
return 0;
}
static int sp805_wdt_expire_now(struct udevice *dev, ulong flags)
{
sp805_wdt_start(dev, 0, flags);
return 0;
}
static int sp805_wdt_probe(struct udevice *dev)
{
debug("%s: Probing wdt%u (sp805-wdt)\n", __func__, dev->seq);
return 0;
}
static int sp805_wdt_ofdata_to_platdata(struct udevice *dev)
{
struct sp805_wdt_priv *priv = dev_get_priv(dev);
priv->reg = (void __iomem *)dev_read_addr(dev);
if (IS_ERR(priv->reg))
return PTR_ERR(priv->reg);
return 0;
}
static const struct wdt_ops sp805_wdt_ops = {
.start = sp805_wdt_start,
.reset = sp805_wdt_reset,
.stop = sp805_wdt_stop,
.expire_now = sp805_wdt_expire_now,
};
static const struct udevice_id sp805_wdt_ids[] = {
{ .compatible = "arm,sp805-wdt" },
{}
};
U_BOOT_DRIVER(sp805_wdt) = {
.name = "sp805_wdt",
.id = UCLASS_WDT,
.of_match = sp805_wdt_ids,
.probe = sp805_wdt_probe,
.priv_auto_alloc_size = sizeof(struct sp805_wdt_priv),
.ofdata_to_platdata = sp805_wdt_ofdata_to_platdata,
.ops = &sp805_wdt_ops,
};