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acrn-kernel/drivers/watchdog/armada_37xx_wdt.c

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// SPDX-License-Identifier: GPL-2.0+
/*
* Watchdog driver for Marvell Armada 37xx SoCs
*
* Author: Marek Behún <kabel@kernel.org>
*/
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/types.h>
#include <linux/watchdog.h>
/*
* There are four counters that can be used for watchdog on Armada 37xx.
* The addresses for counter control registers are register base plus ID*0x10,
* where ID is 0, 1, 2 or 3.
*
* In this driver we use IDs 0 and 1. Counter ID 1 is used as watchdog counter,
* while counter ID 0 is used to implement pinging the watchdog: counter ID 1 is
* set to restart counting from initial value on counter ID 0 end count event.
* Pinging is done by forcing immediate end count event on counter ID 0.
* If only one counter was used, pinging would have to be implemented by
* disabling and enabling the counter, leaving the system in a vulnerable state
* for a (really) short period of time.
*
* Counters ID 2 and 3 are enabled by default even before U-Boot loads,
* therefore this driver does not provide a way to use them, eg. by setting a
* property in device tree.
*/
#define CNTR_ID_RETRIGGER 0
#define CNTR_ID_WDOG 1
/* relative to cpu_misc */
#define WDT_TIMER_SELECT 0x64
#define WDT_TIMER_SELECT_MASK 0xf
#define WDT_TIMER_SELECT_VAL BIT(CNTR_ID_WDOG)
/* relative to reg */
#define CNTR_CTRL(id) ((id) * 0x10)
#define CNTR_CTRL_ENABLE 0x0001
#define CNTR_CTRL_ACTIVE 0x0002
#define CNTR_CTRL_MODE_MASK 0x000c
#define CNTR_CTRL_MODE_ONESHOT 0x0000
#define CNTR_CTRL_MODE_HWSIG 0x000c
#define CNTR_CTRL_TRIG_SRC_MASK 0x00f0
#define CNTR_CTRL_TRIG_SRC_PREV_CNTR 0x0050
#define CNTR_CTRL_PRESCALE_MASK 0xff00
#define CNTR_CTRL_PRESCALE_MIN 2
#define CNTR_CTRL_PRESCALE_SHIFT 8
#define CNTR_COUNT_LOW(id) (CNTR_CTRL(id) + 0x4)
#define CNTR_COUNT_HIGH(id) (CNTR_CTRL(id) + 0x8)
#define WATCHDOG_TIMEOUT 120
static unsigned int timeout;
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout, "Watchdog timeout 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 armada_37xx_watchdog {
struct watchdog_device wdt;
struct regmap *cpu_misc;
void __iomem *reg;
u64 timeout; /* in clock ticks */
unsigned long clk_rate;
struct clk *clk;
};
static u64 get_counter_value(struct armada_37xx_watchdog *dev, int id)
{
u64 val;
/*
* when low is read, high is latched into flip-flops so that it can be
* read consistently without using software debouncing
*/
val = readl(dev->reg + CNTR_COUNT_LOW(id));
val |= ((u64)readl(dev->reg + CNTR_COUNT_HIGH(id))) << 32;
return val;
}
static void set_counter_value(struct armada_37xx_watchdog *dev, int id, u64 val)
{
writel(val & 0xffffffff, dev->reg + CNTR_COUNT_LOW(id));
writel(val >> 32, dev->reg + CNTR_COUNT_HIGH(id));
}
static void counter_enable(struct armada_37xx_watchdog *dev, int id)
{
u32 reg;
reg = readl(dev->reg + CNTR_CTRL(id));
reg |= CNTR_CTRL_ENABLE;
writel(reg, dev->reg + CNTR_CTRL(id));
}
static void counter_disable(struct armada_37xx_watchdog *dev, int id)
{
u32 reg;
reg = readl(dev->reg + CNTR_CTRL(id));
reg &= ~CNTR_CTRL_ENABLE;
writel(reg, dev->reg + CNTR_CTRL(id));
}
static void init_counter(struct armada_37xx_watchdog *dev, int id, u32 mode,
u32 trig_src)
{
u32 reg;
reg = readl(dev->reg + CNTR_CTRL(id));
reg &= ~(CNTR_CTRL_MODE_MASK | CNTR_CTRL_PRESCALE_MASK |
CNTR_CTRL_TRIG_SRC_MASK);
/* set mode */
reg |= mode & CNTR_CTRL_MODE_MASK;
/* set prescaler to the min value */
reg |= CNTR_CTRL_PRESCALE_MIN << CNTR_CTRL_PRESCALE_SHIFT;
/* set trigger source */
reg |= trig_src & CNTR_CTRL_TRIG_SRC_MASK;
writel(reg, dev->reg + CNTR_CTRL(id));
}
static int armada_37xx_wdt_ping(struct watchdog_device *wdt)
{
struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
/* counter 1 is retriggered by forcing end count on counter 0 */
counter_disable(dev, CNTR_ID_RETRIGGER);
counter_enable(dev, CNTR_ID_RETRIGGER);
return 0;
}
static unsigned int armada_37xx_wdt_get_timeleft(struct watchdog_device *wdt)
{
struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
u64 res;
res = get_counter_value(dev, CNTR_ID_WDOG) * CNTR_CTRL_PRESCALE_MIN;
do_div(res, dev->clk_rate);
return res;
}
static int armada_37xx_wdt_set_timeout(struct watchdog_device *wdt,
unsigned int timeout)
{
struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
wdt->timeout = timeout;
/*
* Compute the timeout in clock rate. We use smallest possible
* prescaler, which divides the clock rate by 2
* (CNTR_CTRL_PRESCALE_MIN).
*/
dev->timeout = (u64)dev->clk_rate * timeout;
do_div(dev->timeout, CNTR_CTRL_PRESCALE_MIN);
set_counter_value(dev, CNTR_ID_WDOG, dev->timeout);
return 0;
}
static bool armada_37xx_wdt_is_running(struct armada_37xx_watchdog *dev)
{
u32 reg;
regmap_read(dev->cpu_misc, WDT_TIMER_SELECT, &reg);
if ((reg & WDT_TIMER_SELECT_MASK) != WDT_TIMER_SELECT_VAL)
return false;
reg = readl(dev->reg + CNTR_CTRL(CNTR_ID_WDOG));
return !!(reg & CNTR_CTRL_ACTIVE);
}
static int armada_37xx_wdt_start(struct watchdog_device *wdt)
{
struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
/* select counter 1 as watchdog counter */
regmap_write(dev->cpu_misc, WDT_TIMER_SELECT, WDT_TIMER_SELECT_VAL);
/* init counter 0 as retrigger counter for counter 1 */
init_counter(dev, CNTR_ID_RETRIGGER, CNTR_CTRL_MODE_ONESHOT, 0);
set_counter_value(dev, CNTR_ID_RETRIGGER, 0);
/* init counter 1 to be retriggerable by counter 0 end count */
init_counter(dev, CNTR_ID_WDOG, CNTR_CTRL_MODE_HWSIG,
CNTR_CTRL_TRIG_SRC_PREV_CNTR);
set_counter_value(dev, CNTR_ID_WDOG, dev->timeout);
/* enable counter 1 */
counter_enable(dev, CNTR_ID_WDOG);
/* start counter 1 by forcing immediate end count on counter 0 */
counter_enable(dev, CNTR_ID_RETRIGGER);
return 0;
}
static int armada_37xx_wdt_stop(struct watchdog_device *wdt)
{
struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
counter_disable(dev, CNTR_ID_WDOG);
counter_disable(dev, CNTR_ID_RETRIGGER);
regmap_write(dev->cpu_misc, WDT_TIMER_SELECT, 0);
return 0;
}
static const struct watchdog_info armada_37xx_wdt_info = {
.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
.identity = "Armada 37xx Watchdog",
};
static const struct watchdog_ops armada_37xx_wdt_ops = {
.owner = THIS_MODULE,
.start = armada_37xx_wdt_start,
.stop = armada_37xx_wdt_stop,
.ping = armada_37xx_wdt_ping,
.set_timeout = armada_37xx_wdt_set_timeout,
.get_timeleft = armada_37xx_wdt_get_timeleft,
};
static void armada_clk_disable_unprepare(void *data)
{
clk_disable_unprepare(data);
}
static int armada_37xx_wdt_probe(struct platform_device *pdev)
{
struct armada_37xx_watchdog *dev;
struct resource *res;
struct regmap *regmap;
int ret;
dev = devm_kzalloc(&pdev->dev, sizeof(struct armada_37xx_watchdog),
GFP_KERNEL);
if (!dev)
return -ENOMEM;
dev->wdt.info = &armada_37xx_wdt_info;
dev->wdt.ops = &armada_37xx_wdt_ops;
regmap = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
"marvell,system-controller");
if (IS_ERR(regmap))
return PTR_ERR(regmap);
dev->cpu_misc = regmap;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -ENODEV;
dev->reg = devm_ioremap(&pdev->dev, res->start, resource_size(res));
if (!dev->reg)
return -ENOMEM;
/* init clock */
dev->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(dev->clk))
return PTR_ERR(dev->clk);
ret = clk_prepare_enable(dev->clk);
if (ret)
return ret;
ret = devm_add_action_or_reset(&pdev->dev,
armada_clk_disable_unprepare, dev->clk);
if (ret)
return ret;
dev->clk_rate = clk_get_rate(dev->clk);
if (!dev->clk_rate)
return -EINVAL;
/*
* Since the timeout in seconds is given as 32 bit unsigned int, and
* the counters hold 64 bit values, even after multiplication by clock
* rate the counter can hold timeout of UINT_MAX seconds.
*/
dev->wdt.min_timeout = 1;
dev->wdt.max_timeout = UINT_MAX;
dev->wdt.parent = &pdev->dev;
/* default value, possibly override by module parameter or dtb */
dev->wdt.timeout = WATCHDOG_TIMEOUT;
watchdog_init_timeout(&dev->wdt, timeout, &pdev->dev);
platform_set_drvdata(pdev, &dev->wdt);
watchdog_set_drvdata(&dev->wdt, dev);
armada_37xx_wdt_set_timeout(&dev->wdt, dev->wdt.timeout);
if (armada_37xx_wdt_is_running(dev))
set_bit(WDOG_HW_RUNNING, &dev->wdt.status);
watchdog_set_nowayout(&dev->wdt, nowayout);
watchdog_stop_on_reboot(&dev->wdt);
ret = devm_watchdog_register_device(&pdev->dev, &dev->wdt);
if (ret)
return ret;
dev_info(&pdev->dev, "Initial timeout %d sec%s\n",
dev->wdt.timeout, nowayout ? ", nowayout" : "");
return 0;
}
static int __maybe_unused armada_37xx_wdt_suspend(struct device *dev)
{
struct watchdog_device *wdt = dev_get_drvdata(dev);
return armada_37xx_wdt_stop(wdt);
}
static int __maybe_unused armada_37xx_wdt_resume(struct device *dev)
{
struct watchdog_device *wdt = dev_get_drvdata(dev);
if (watchdog_active(wdt))
return armada_37xx_wdt_start(wdt);
return 0;
}
static const struct dev_pm_ops armada_37xx_wdt_dev_pm_ops = {
SET_SYSTEM_SLEEP_PM_OPS(armada_37xx_wdt_suspend,
armada_37xx_wdt_resume)
};
#ifdef CONFIG_OF
static const struct of_device_id armada_37xx_wdt_match[] = {
{ .compatible = "marvell,armada-3700-wdt", },
{},
};
MODULE_DEVICE_TABLE(of, armada_37xx_wdt_match);
#endif
static struct platform_driver armada_37xx_wdt_driver = {
.probe = armada_37xx_wdt_probe,
.driver = {
.name = "armada_37xx_wdt",
.of_match_table = of_match_ptr(armada_37xx_wdt_match),
.pm = &armada_37xx_wdt_dev_pm_ops,
},
};
module_platform_driver(armada_37xx_wdt_driver);
MODULE_AUTHOR("Marek Behun <kabel@kernel.org>");
MODULE_DESCRIPTION("Armada 37xx CPU Watchdog");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:armada_37xx_wdt");
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