Date:   Mon, 6 Nov 2017 10:06:06 +0800
From:   Eric Long <eric.long@...eadtrum.com>
To:     Guenter Roeck <linux@...ck-us.net>, <eric.long@...eadtrum.com>
CC:     Wim Van Sebroeck <wim@...ana.be>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, <baolin.wang@...aro.org>,
        <linux-watchdog@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [v5,2/2] watchdog: Add Spreadtrum watchdog driver

On Fri, Nov 03, 2017 at 06:48:26AM -0700, Guenter Roeck wrote:
> On Fri, Nov 03, 2017 at 07:18:28PM +0800, Eric Long wrote:
> > This patch adds the watchdog driver for Spreadtrum SC9860 platform.
> > 
> > Signed-off-by: Eric Long <eric.long@...eadtrum.com>
> > ---
> > Changes since v4:
> >  - Remove sprd_wdt_remove().
> >  - Add devm_add_action() for sprd_wdt_disable().
> > 
> > Changes since v3:
> >  - Update Kconfig SPRD_WATCHDOG help messages.
> >  - Correct the wrong spell words.
> >  - Rename SPRD_WDT_CNT_HIGH_VALUE as SPRD_WDT_CNT_HIGH_SHIFT.
> >  - Remove unused macor.
> >  - Update sprd_wdt_set_pretimeout() api.
> >  - Add wdt->wdd.timeout default value.
> >  - Use devm_watchdog_register_device() to register wdt device.
> >  - If module does not support NOWAYOUT, disable wdt when remove this driver.
> >  - Call sprd_wdt_disable() every wdt suspend.
> > 
> > Changes since v2:
> >  - Rename all the macors, add SPRD tag at the head of the macro names.
> >  - Rename SPRD_WDT_CLK as SPRD_WTC_CNT_STEP.
> >  - Remove the code which check timeout value at the wrong place.
> >  - Add min/max timeout value limit.
> >  - Remove set WDOG_HW_RUNNING status at sprd_wdt_enable().
> >  - Add timeout/pretimeout judgment when set them.
> >  - Support WATCHDOG_NOWAYOUT status.
> > 
> > Changes since v1:
> >  - Use pretimeout instead of own implementation.
> >  - Fix timeout loop when loading timeout values.
> >  - use the infrastructure to read and set "timeout-sec" property.
> >  - Add conditions when start or stop watchdog.
> >  - Change the position of enabling watchdog.
> >  - Other optimization.
> > ---
> >  drivers/watchdog/Kconfig    |   8 +
> >  drivers/watchdog/Makefile   |   1 +
> >  drivers/watchdog/sprd_wdt.c | 407 ++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 416 insertions(+)
> >  create mode 100644 drivers/watchdog/sprd_wdt.c
> > 
> > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> > index c722cbf..3367a8c 100644
> > --- a/drivers/watchdog/Kconfig
> > +++ b/drivers/watchdog/Kconfig
> > @@ -787,6 +787,14 @@ config UNIPHIER_WATCHDOG
> >  	  To compile this driver as a module, choose M here: the
> >  	  module will be called uniphier_wdt.
> >  
> > +config SPRD_WATCHDOG
> > +	tristate "Spreadtrum watchdog support"
> > +	depends on ARCH_SPRD || COMPILE_TEST
> > +	select WATCHDOG_CORE
> > +	help
> > +	  Say Y here to include watchdog timer supported
> > +	  by Spreadtrum system.
> > +
> >  # AVR32 Architecture
> >  
> >  config AT32AP700X_WDT
> > diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> > index 56adf9f..187cca2 100644
> > --- a/drivers/watchdog/Makefile
> > +++ b/drivers/watchdog/Makefile
> > @@ -87,6 +87,7 @@ obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o
> >  obj-$(CONFIG_ZX2967_WATCHDOG) += zx2967_wdt.o
> >  obj-$(CONFIG_STM32_WATCHDOG) += stm32_iwdg.o
> >  obj-$(CONFIG_UNIPHIER_WATCHDOG) += uniphier_wdt.o
> > +obj-$(CONFIG_SPRD_WATCHDOG) += sprd_wdt.o
> >  
> >  # AVR32 Architecture
> >  obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
> > diff --git a/drivers/watchdog/sprd_wdt.c b/drivers/watchdog/sprd_wdt.c
> > new file mode 100644
> > index 0000000..88f6f84
> > --- /dev/null
> > +++ b/drivers/watchdog/sprd_wdt.c
> > @@ -0,0 +1,407 @@
> > +/*
> > + * Spreadtrum watchdog driver
> > + * Copyright (C) 2017 Spreadtrum - http://www.spreadtrum.com
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify it under the terms of the GNU General Public License
> > + * version 2 as published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope that it will be useful, but
> > + * WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > + * General Public License for more details.
> > + */
> > +
> > +#include <linux/bitops.h>
> > +#include <linux/clk.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		1000
> > +
> > +struct sprd_wdt {
> > +	void __iomem *base;
> > +	struct watchdog_device wdd;
> > +	struct clk *enable;
> > +	struct clk *rtc_enable;
> > +	unsigned 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 inline bool sprd_wdt_is_running(struct sprd_wdt *wdt)
> > +{
> > +	u32 val;
> > +
> > +	val = readl_relaxed(wdt->base + SPRD_WDT_CTRL);
> > +	return val & SPRD_WDT_NEW_VER_EN;
> > +}
> > +
> > +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;
> > +
> > +	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);
> > +
> > +	/*
> > +	 * Waiting the load value operation done,
> > +	 * it needs two or three RTC clock cycles.
> > +	 */
> > +	do {
> > +		val = readl_relaxed(wdt->base + SPRD_WDT_INT_RAW);
> > +		if (!(val & SPRD_WDT_LD_BUSY_BIT))
> > +			break;
> > +
> > +		cpu_relax();
> > +	} while (delay_cnt++ < SPRD_WDT_LOAD_TIMEOUT);
> > +
> > +	if (delay_cnt >= SPRD_WDT_LOAD_TIMEOUT)
> > +		return -EBUSY;
> > +	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)
> > +		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);
> > +	val = val / SPRD_WDT_CNT_STEP;
> > +
> > +	return val;
> > +}
> > +
> > +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 resource *wdt_res;
> > +	struct sprd_wdt *wdt;
> > +	int ret;
> > +
> > +	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
> > +	if (!wdt)
> > +		return -ENOMEM;
> > +
> > +	wdt_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +	wdt->base = devm_ioremap_resource(&pdev->dev, wdt_res);
> > +	if (IS_ERR(wdt->base)) {
> > +		dev_err(&pdev->dev, "failed to map memory resource\n");
> > +		return PTR_ERR(wdt->base);
> > +	}
> > +
> > +	wdt->enable = devm_clk_get(&pdev->dev, "enable");
> > +	if (IS_ERR(wdt->enable)) {
> > +		dev_err(&pdev->dev, "can't get the enable clock\n");
> > +		return PTR_ERR(wdt->enable);
> > +	}
> > +
> > +	wdt->rtc_enable = devm_clk_get(&pdev->dev, "rtc_enable");
> > +	if (IS_ERR(wdt->rtc_enable)) {
> > +		dev_err(&pdev->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) {
> 
> Please test compile your code and look out for warnings.
> 
> drivers/watchdog/sprd_wdt.c: In function ‘sprd_wdt_probe’:
> drivers/watchdog/sprd_wdt.c:306:15: warning: comparison of unsigned expression <
> 0 is always false 
> 
> wdt->irq is unsigned.
>

Yes, you are right, I will fix it. Thank you.

> > +		dev_err(&pdev->dev, "failed to get IRQ resource\n");
> > +		return wdt->irq;
> > +	}
> > +
> > +	ret = devm_request_irq(&pdev->dev, wdt->irq, sprd_wdt_isr,
> > +			       IRQF_NO_SUSPEND, "sprd-wdt", (void *)wdt);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "failed to register irq\n");
> > +		return ret;
> > +	}
> > +
> > +	wdt->wdd.info = &sprd_wdt_info;
> > +	wdt->wdd.ops = &sprd_wdt_ops;
> > +	wdt->wdd.parent = &pdev->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(&pdev->dev, "failed to enable wdt\n");
> > +		return ret;
> > +	}
> > +	ret = devm_add_action(&pdev->dev, sprd_wdt_disable, wdt);
> > +	if (ret) {
> > +		sprd_wdt_disable(wdt);
> > +		dev_err(&pdev->dev, "Failed to add wdt disable action\n");
> > +		return ret;
> > +	}
> > +
> > +	watchdog_set_nowayout(&wdt->wdd, WATCHDOG_NOWAYOUT);
> > +	watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev);
> > +
> > +	ret = devm_watchdog_register_device(&pdev->dev, &wdt->wdd);
> > +	if (ret) {
> > +		sprd_wdt_disable(wdt);
> > +		dev_err(&pdev->dev, "failed to register watchdog\n");
> > +		return ret;
> > +	}
> > +	platform_set_drvdata(pdev, wdt);
> > +
> > +	return 0;
> > +}
> > +
> > +static int __maybe_unused sprd_wdt_pm_suspend(struct device *dev)
> > +{
> > +	struct watchdog_device *wdd = dev_get_drvdata(dev);
> > +	struct sprd_wdt *wdt = dev_get_drvdata(dev);
> > +
> > +	if (watchdog_active(wdd))
> > +		sprd_wdt_stop(&wdt->wdd);
> > +	sprd_wdt_disable(wdt);
> > +
> > +	return 0;
> > +}
> > +
> > +static int __maybe_unused sprd_wdt_pm_resume(struct device *dev)
> > +{
> > +	struct watchdog_device *wdd = dev_get_drvdata(dev);
> > +	struct sprd_wdt *wdt = dev_get_drvdata(dev);
> > +	int ret;
> > +
> > +	ret = sprd_wdt_enable(wdt);
> > +	if (ret)
> > +		return ret;
> > +
> > +	if (watchdog_active(wdd)) {
> > +		ret = sprd_wdt_start(&wdt->wdd);
> > +		if (ret) {
> > +			sprd_wdt_disable(wdt);
> > +			return ret;
> > +		}
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +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@...eadtrum.com>");
> > +MODULE_DESCRIPTION("Spreadtrum Watchdog Timer Controller Driver");
> > +MODULE_LICENSE("GPL v2");

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