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linux-next/drivers/watchdog/sprd_wdt.c
Chunyan Zhang 2a6c9c65b2 watchdog: sprd: change to use usleep_range() instead of busy loop 
After changing to check busy bit for the previous loading operation instead
of the current one, for most of cases, the busy bit is not set for the
first time of read, so there's no need to check so frequently, so this
patch use usleep_range() to replace cpu_relax() to avoid busy loop.

Also this patch change the max times to 11 which would be enough, since
according to the specification, the busy bit would be set after a new
loading operation and last 2 or 3 RTC clock cycles (about 60us~92us).

Fixes: 4776034670 ("watchdog: Add Spreadtrum watchdog driver")
Original-by: Lingling Xu <ling_ling.xu@unisoc.com>
Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20201029023933.24548-4-zhang.lyra@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
2020-12-13 16:17:39 +01:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Spreadtrum watchdog driver
* Copyright (C) 2017 Spreadtrum - http://www.spreadtrum.com
*/
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#define SPRD_WDT_LOAD_LOW 0x0
#define SPRD_WDT_LOAD_HIGH 0x4
#define SPRD_WDT_CTRL 0x8
#define SPRD_WDT_INT_CLR 0xc
#define SPRD_WDT_INT_RAW 0x10
#define SPRD_WDT_INT_MSK 0x14
#define SPRD_WDT_CNT_LOW 0x18
#define SPRD_WDT_CNT_HIGH 0x1c
#define SPRD_WDT_LOCK 0x20
#define SPRD_WDT_IRQ_LOAD_LOW 0x2c
#define SPRD_WDT_IRQ_LOAD_HIGH 0x30
/* WDT_CTRL */
#define SPRD_WDT_INT_EN_BIT BIT(0)
#define SPRD_WDT_CNT_EN_BIT BIT(1)
#define SPRD_WDT_NEW_VER_EN BIT(2)
#define SPRD_WDT_RST_EN_BIT BIT(3)
/* WDT_INT_CLR */
#define SPRD_WDT_INT_CLEAR_BIT BIT(0)
#define SPRD_WDT_RST_CLEAR_BIT BIT(3)
/* WDT_INT_RAW */
#define SPRD_WDT_INT_RAW_BIT BIT(0)
#define SPRD_WDT_RST_RAW_BIT BIT(3)
#define SPRD_WDT_LD_BUSY_BIT BIT(4)
/* 1s equal to 32768 counter steps */
#define SPRD_WDT_CNT_STEP 32768
#define SPRD_WDT_UNLOCK_KEY 0xe551
#define SPRD_WDT_MIN_TIMEOUT 3
#define SPRD_WDT_MAX_TIMEOUT 60
#define SPRD_WDT_CNT_HIGH_SHIFT 16
#define SPRD_WDT_LOW_VALUE_MASK GENMASK(15, 0)
#define SPRD_WDT_LOAD_TIMEOUT 11
struct sprd_wdt {
void __iomem *base;
struct watchdog_device wdd;
struct clk *enable;
struct clk *rtc_enable;
int irq;
};
static inline struct sprd_wdt *to_sprd_wdt(struct watchdog_device *wdd)
{
return container_of(wdd, struct sprd_wdt, wdd);
}
static inline void sprd_wdt_lock(void __iomem *addr)
{
writel_relaxed(0x0, addr + SPRD_WDT_LOCK);
}
static inline void sprd_wdt_unlock(void __iomem *addr)
{
writel_relaxed(SPRD_WDT_UNLOCK_KEY, addr + SPRD_WDT_LOCK);
}
static irqreturn_t sprd_wdt_isr(int irq, void *dev_id)
{
struct sprd_wdt *wdt = (struct sprd_wdt *)dev_id;
sprd_wdt_unlock(wdt->base);
writel_relaxed(SPRD_WDT_INT_CLEAR_BIT, wdt->base + SPRD_WDT_INT_CLR);
sprd_wdt_lock(wdt->base);
watchdog_notify_pretimeout(&wdt->wdd);
return IRQ_HANDLED;
}
static u32 sprd_wdt_get_cnt_value(struct sprd_wdt *wdt)
{
u32 val;
val = readl_relaxed(wdt->base + SPRD_WDT_CNT_HIGH) <<
SPRD_WDT_CNT_HIGH_SHIFT;
val |= readl_relaxed(wdt->base + SPRD_WDT_CNT_LOW) &
SPRD_WDT_LOW_VALUE_MASK;
return val;
}
static int sprd_wdt_load_value(struct sprd_wdt *wdt, u32 timeout,
u32 pretimeout)
{
u32 val, delay_cnt = 0;
u32 tmr_step = timeout * SPRD_WDT_CNT_STEP;
u32 prtmr_step = pretimeout * SPRD_WDT_CNT_STEP;
/*
* Checking busy bit to make sure the previous loading operation is
* done. According to the specification, the busy bit would be set
* after a new loading operation and last 2 or 3 RTC clock
* cycles (about 60us~92us).
*/
do {
val = readl_relaxed(wdt->base + SPRD_WDT_INT_RAW);
if (!(val & SPRD_WDT_LD_BUSY_BIT))
break;
usleep_range(10, 100);
} while (delay_cnt++ < SPRD_WDT_LOAD_TIMEOUT);
if (delay_cnt >= SPRD_WDT_LOAD_TIMEOUT)
return -EBUSY;
sprd_wdt_unlock(wdt->base);
writel_relaxed((tmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
SPRD_WDT_LOW_VALUE_MASK, wdt->base + SPRD_WDT_LOAD_HIGH);
writel_relaxed((tmr_step & SPRD_WDT_LOW_VALUE_MASK),
wdt->base + SPRD_WDT_LOAD_LOW);
writel_relaxed((prtmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
SPRD_WDT_LOW_VALUE_MASK,
wdt->base + SPRD_WDT_IRQ_LOAD_HIGH);
writel_relaxed(prtmr_step & SPRD_WDT_LOW_VALUE_MASK,
wdt->base + SPRD_WDT_IRQ_LOAD_LOW);
sprd_wdt_lock(wdt->base);
return 0;
}
static int sprd_wdt_enable(struct sprd_wdt *wdt)
{
u32 val;
int ret;
ret = clk_prepare_enable(wdt->enable);
if (ret)
return ret;
ret = clk_prepare_enable(wdt->rtc_enable);
if (ret) {
clk_disable_unprepare(wdt->enable);
return ret;
}
sprd_wdt_unlock(wdt->base);
val = readl_relaxed(wdt->base + SPRD_WDT_CTRL);
val |= SPRD_WDT_NEW_VER_EN;
writel_relaxed(val, wdt->base + SPRD_WDT_CTRL);
sprd_wdt_lock(wdt->base);
return 0;
}
static void sprd_wdt_disable(void *_data)
{
struct sprd_wdt *wdt = _data;
sprd_wdt_unlock(wdt->base);
writel_relaxed(0x0, wdt->base + SPRD_WDT_CTRL);
sprd_wdt_lock(wdt->base);
clk_disable_unprepare(wdt->rtc_enable);
clk_disable_unprepare(wdt->enable);
}
static int sprd_wdt_start(struct watchdog_device *wdd)
{
struct sprd_wdt *wdt = to_sprd_wdt(wdd);
u32 val;
int ret;
ret = sprd_wdt_load_value(wdt, wdd->timeout, wdd->pretimeout);
if (ret)
return ret;
sprd_wdt_unlock(wdt->base);
val = readl_relaxed(wdt->base + SPRD_WDT_CTRL);
val |= SPRD_WDT_CNT_EN_BIT | SPRD_WDT_INT_EN_BIT | SPRD_WDT_RST_EN_BIT;
writel_relaxed(val, wdt->base + SPRD_WDT_CTRL);
sprd_wdt_lock(wdt->base);
set_bit(WDOG_HW_RUNNING, &wdd->status);
return 0;
}
static int sprd_wdt_stop(struct watchdog_device *wdd)
{
struct sprd_wdt *wdt = to_sprd_wdt(wdd);
u32 val;
sprd_wdt_unlock(wdt->base);
val = readl_relaxed(wdt->base + SPRD_WDT_CTRL);
val &= ~(SPRD_WDT_CNT_EN_BIT | SPRD_WDT_RST_EN_BIT |
SPRD_WDT_INT_EN_BIT);
writel_relaxed(val, wdt->base + SPRD_WDT_CTRL);
sprd_wdt_lock(wdt->base);
return 0;
}
static int sprd_wdt_set_timeout(struct watchdog_device *wdd,
u32 timeout)
{
struct sprd_wdt *wdt = to_sprd_wdt(wdd);
if (timeout == wdd->timeout)
return 0;
wdd->timeout = timeout;
return sprd_wdt_load_value(wdt, timeout, wdd->pretimeout);
}
static int sprd_wdt_set_pretimeout(struct watchdog_device *wdd,
u32 new_pretimeout)
{
struct sprd_wdt *wdt = to_sprd_wdt(wdd);
if (new_pretimeout < wdd->min_timeout)
return -EINVAL;
wdd->pretimeout = new_pretimeout;
return sprd_wdt_load_value(wdt, wdd->timeout, new_pretimeout);
}
static u32 sprd_wdt_get_timeleft(struct watchdog_device *wdd)
{
struct sprd_wdt *wdt = to_sprd_wdt(wdd);
u32 val;
val = sprd_wdt_get_cnt_value(wdt);
return val / SPRD_WDT_CNT_STEP;
}
static const struct watchdog_ops sprd_wdt_ops = {
.owner = THIS_MODULE,
.start = sprd_wdt_start,
.stop = sprd_wdt_stop,
.set_timeout = sprd_wdt_set_timeout,
.set_pretimeout = sprd_wdt_set_pretimeout,
.get_timeleft = sprd_wdt_get_timeleft,
};
static const struct watchdog_info sprd_wdt_info = {
.options = WDIOF_SETTIMEOUT |
WDIOF_PRETIMEOUT |
WDIOF_MAGICCLOSE |
WDIOF_KEEPALIVEPING,
.identity = "Spreadtrum Watchdog Timer",
};
static int sprd_wdt_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct sprd_wdt *wdt;
int ret;
wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
if (!wdt)
return -ENOMEM;
wdt->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(wdt->base))
return PTR_ERR(wdt->base);
wdt->enable = devm_clk_get(dev, "enable");
if (IS_ERR(wdt->enable)) {
dev_err(dev, "can't get the enable clock\n");
return PTR_ERR(wdt->enable);
}
wdt->rtc_enable = devm_clk_get(dev, "rtc_enable");
if (IS_ERR(wdt->rtc_enable)) {
dev_err(dev, "can't get the rtc enable clock\n");
return PTR_ERR(wdt->rtc_enable);
}
wdt->irq = platform_get_irq(pdev, 0);
if (wdt->irq < 0)
return wdt->irq;
ret = devm_request_irq(dev, wdt->irq, sprd_wdt_isr, IRQF_NO_SUSPEND,
"sprd-wdt", (void *)wdt);
if (ret) {
dev_err(dev, "failed to register irq\n");
return ret;
}
wdt->wdd.info = &sprd_wdt_info;
wdt->wdd.ops = &sprd_wdt_ops;
wdt->wdd.parent = dev;
wdt->wdd.min_timeout = SPRD_WDT_MIN_TIMEOUT;
wdt->wdd.max_timeout = SPRD_WDT_MAX_TIMEOUT;
wdt->wdd.timeout = SPRD_WDT_MAX_TIMEOUT;
ret = sprd_wdt_enable(wdt);
if (ret) {
dev_err(dev, "failed to enable wdt\n");
return ret;
}
ret = devm_add_action_or_reset(dev, sprd_wdt_disable, wdt);
if (ret) {
dev_err(dev, "Failed to add wdt disable action\n");
return ret;
}
watchdog_set_nowayout(&wdt->wdd, WATCHDOG_NOWAYOUT);
watchdog_init_timeout(&wdt->wdd, 0, dev);
ret = devm_watchdog_register_device(dev, &wdt->wdd);
if (ret) {
sprd_wdt_disable(wdt);
return ret;
}
platform_set_drvdata(pdev, wdt);
return 0;
}
static int __maybe_unused sprd_wdt_pm_suspend(struct device *dev)
{
struct sprd_wdt *wdt = dev_get_drvdata(dev);
if (watchdog_active(&wdt->wdd))
sprd_wdt_stop(&wdt->wdd);
sprd_wdt_disable(wdt);
return 0;
}
static int __maybe_unused sprd_wdt_pm_resume(struct device *dev)
{
struct sprd_wdt *wdt = dev_get_drvdata(dev);
int ret;
ret = sprd_wdt_enable(wdt);
if (ret)
return ret;
if (watchdog_active(&wdt->wdd))
ret = sprd_wdt_start(&wdt->wdd);
return ret;
}
static const struct dev_pm_ops sprd_wdt_pm_ops = {
SET_SYSTEM_SLEEP_PM_OPS(sprd_wdt_pm_suspend,
sprd_wdt_pm_resume)
};
static const struct of_device_id sprd_wdt_match_table[] = {
{ .compatible = "sprd,sp9860-wdt", },
{},
};
MODULE_DEVICE_TABLE(of, sprd_wdt_match_table);
static struct platform_driver sprd_watchdog_driver = {
.probe = sprd_wdt_probe,
.driver = {
.name = "sprd-wdt",
.of_match_table = sprd_wdt_match_table,
.pm = &sprd_wdt_pm_ops,
},
};
module_platform_driver(sprd_watchdog_driver);
MODULE_AUTHOR("Eric Long <eric.long@spreadtrum.com>");
MODULE_DESCRIPTION("Spreadtrum Watchdog Timer Controller Driver");
MODULE_LICENSE("GPL v2");
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