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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2020 TOSHIBA CORPORATION
* Copyright (c) 2020 Toshiba Electronic Devices & Storage Corporation
* Copyright (c) 2020 Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
*/
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#define WDT_CNT 0x00
#define WDT_MIN 0x04
#define WDT_MAX 0x08
#define WDT_CTL 0x0c
#define WDT_CMD 0x10
#define WDT_CMD_CLEAR 0x4352
#define WDT_CMD_START_STOP 0x5354
#define WDT_DIV 0x30
#define VISCONTI_WDT_FREQ 2000000 /* 2MHz */
#define WDT_DEFAULT_TIMEOUT 10U /* in seconds */
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(
nowayout,
"Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT)")");
struct visconti_wdt_priv {
struct watchdog_device wdev;
void __iomem *base;
u32 div;
};
static int visconti_wdt_start(struct watchdog_device *wdev)
{
struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
writel(priv->div, priv->base + WDT_DIV);
writel(0, priv->base + WDT_MIN);
writel(timeout, priv->base + WDT_MAX);
writel(0, priv->base + WDT_CTL);
writel(WDT_CMD_START_STOP, priv->base + WDT_CMD);
return 0;
}
static int visconti_wdt_stop(struct watchdog_device *wdev)
{
struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
writel(1, priv->base + WDT_CTL);
writel(WDT_CMD_START_STOP, priv->base + WDT_CMD);
return 0;
}
static int visconti_wdt_ping(struct watchdog_device *wdd)
{
struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdd);
writel(WDT_CMD_CLEAR, priv->base + WDT_CMD);
return 0;
}
static unsigned int visconti_wdt_get_timeleft(struct watchdog_device *wdev)
{
struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
u32 cnt = readl(priv->base + WDT_CNT);
if (timeout <= cnt)
return 0;
timeout -= cnt;
return timeout / VISCONTI_WDT_FREQ;
}
static int visconti_wdt_set_timeout(struct watchdog_device *wdev, unsigned int timeout)
{
u32 val;
struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
wdev->timeout = timeout;
val = wdev->timeout * VISCONTI_WDT_FREQ;
/* Clear counter before setting timeout because WDT expires */
writel(WDT_CMD_CLEAR, priv->base + WDT_CMD);
writel(val, priv->base + WDT_MAX);
return 0;
}
static const struct watchdog_info visconti_wdt_info = {
.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
.identity = "Visconti Watchdog",
};
static const struct watchdog_ops visconti_wdt_ops = {
.owner = THIS_MODULE,
.start = visconti_wdt_start,
.stop = visconti_wdt_stop,
.ping = visconti_wdt_ping,
.get_timeleft = visconti_wdt_get_timeleft,
.set_timeout = visconti_wdt_set_timeout,
};
static void visconti_clk_disable_unprepare(void *data)
{
clk_disable_unprepare(data);
}
static int visconti_wdt_probe(struct platform_device *pdev)
{
struct watchdog_device *wdev;
struct visconti_wdt_priv *priv;
struct device *dev = &pdev->dev;
struct clk *clk;
int ret;
unsigned long clk_freq;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(priv->base))
return PTR_ERR(priv->base);
clk = devm_clk_get(dev, NULL);
if (IS_ERR(clk))
return dev_err_probe(dev, PTR_ERR(clk), "Could not get clock\n");
ret = clk_prepare_enable(clk);
if (ret) {
dev_err(dev, "Could not enable clock\n");
return ret;
}
ret = devm_add_action_or_reset(dev, visconti_clk_disable_unprepare, clk);
if (ret)
return ret;
clk_freq = clk_get_rate(clk);
if (!clk_freq)
return -EINVAL;
priv->div = clk_freq / VISCONTI_WDT_FREQ;
/* Initialize struct watchdog_device. */
wdev = &priv->wdev;
wdev->info = &visconti_wdt_info;
wdev->ops = &visconti_wdt_ops;
wdev->parent = dev;
wdev->min_timeout = 1;
wdev->max_timeout = 0xffffffff / VISCONTI_WDT_FREQ;
wdev->timeout = min(wdev->max_timeout, WDT_DEFAULT_TIMEOUT);
watchdog_set_drvdata(wdev, priv);
watchdog_set_nowayout(wdev, nowayout);
watchdog_stop_on_unregister(wdev);
/* This overrides the default timeout only if DT configuration was found */
ret = watchdog_init_timeout(wdev, 0, dev);
if (ret)
dev_warn(dev, "Specified timeout value invalid, using default\n");
return devm_watchdog_register_device(dev, wdev);
}
static const struct of_device_id visconti_wdt_of_match[] = {
{ .compatible = "toshiba,visconti-wdt", },
{}
};
MODULE_DEVICE_TABLE(of, visconti_wdt_of_match);
static struct platform_driver visconti_wdt_driver = {
.driver = {
.name = "visconti_wdt",
.of_match_table = visconti_wdt_of_match,
},
.probe = visconti_wdt_probe,
};
module_platform_driver(visconti_wdt_driver);
MODULE_DESCRIPTION("TOSHIBA Visconti Watchdog Driver");
MODULE_AUTHOR("Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp");
MODULE_LICENSE("GPL v2");
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