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SubjectRe: [PATCH 2/2] watchdog: Add Spreadtrum watchdog driver
On Sat, Sep 09, 2017 at 03:32:48AM +0000, Guenter Roeck wrote:
> On 09/05/2017 10:38 PM, Eric Long wrote:
> > This patch adds the watchdog driver for Spreadtrum SC9860 platform.
> >
> > Signed-off-by: Eric Long <eric.long@spreadtrum.com>
> > ---
> > drivers/watchdog/Kconfig | 8 +
> > drivers/watchdog/Makefile | 1 +
> > drivers/watchdog/sprd_wdt.c | 366 ++++++++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 375 insertions(+)
> > create mode 100644 drivers/watchdog/sprd_wdt.c
> >
> > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> > index c722cbf..ea07718 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
> > + select WATCHDOG_CORE
> > + help
> > + Say Y here to include support watchdog timer embedded
> > + into the 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..6006bb4
> > --- /dev/null
> > +++ b/drivers/watchdog/sprd_wdt.c
> > @@ -0,0 +1,366 @@
> > +/*
> > + * 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/clk.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 WDT_LOAD_LOW 0x0
> > +#define WDT_LOAD_HIGH 0x4
> > +#define WDT_CTRL 0x8
> > +#define WDT_INT_CLR 0xc
> > +#define WDT_INT_RAW 0x10
> > +#define WDT_INT_MSK 0x14
> > +#define WDT_CNT_LOW 0x18
> > +#define WDT_CNT_HIGH 0x1c
> > +#define WDT_LOCK 0x20
> > +#define WDT_IRQ_LOAD_LOW 0x2c
> > +#define WDT_IRQ_LOAD_HIGH 0x30
> > +
> > +/* WDT_CTRL */
> > +#define WDT_INT_EN_BIT BIT(0)
> > +#define WDT_CNT_EN_BIT BIT(1)
> > +#define WDT_NEW_VER_EN BIT(2)
> > +#define WDT_RST_EN_BIT BIT(3)
> > +
> > +/* WDT_INT_CLR */
> > +#define WDT_INT_CLEAR_BIT BIT(0)
> > +#define WDT_RST_CLEAR_BIT BIT(3)
> > +
> > +/* WDT_INT_RAW */
> > +#define WDT_INT_RAW_BIT BIT(0)
> > +#define WDT_RST_RAW_BIT BIT(3)
> > +#define WDT_LD_BUSY_BIT BIT(4)
> > +
> > +#define WDT_CLK 32768
> > +#define WDT_UNLOCK_KEY 0xe551
> > +#define WDT_IRQ_TMROUT_OFFSET 0x3
> > +
> > +#define WDT_CNT_VALUE_SIZE 16
> > +#define WDT_CNT_VALUE_MASK GENMASK(15, 0)
> > +#define WDT_LOAD_TIMEOUT_NUM 10000
> > +
> > +struct sprd_wdt {
> > + void __iomem *base;
> > + struct watchdog_device wdd;
> > + struct clk *enable;
> > + struct clk *rtc_enable;
> > + u32 irq_tmr_out;
> > + u32 rst_tmr_out;
> > + 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 + WDT_LOCK);
> > +}
> > +
> > +static inline void sprd_wdt_unlock(void __iomem *addr)
> > +{
> > + writel_relaxed(WDT_UNLOCK_KEY, addr + 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(WDT_INT_CLEAR_BIT, wdt->base + 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 + WDT_CNT_HIGH) << WDT_CNT_VALUE_SIZE;
> > + val |= readl_relaxed(wdt->base + WDT_CNT_LOW) & WDT_CNT_VALUE_MASK;
> > +
> > + return val;
> > +}
> > +
> > +static int sprd_wdt_load_value(struct sprd_wdt *wdt, u32 rst_value,
> > + u32 irq_value)
> > +{
> > + u32 val, cnt = 0;
> > +
> > + sprd_wdt_unlock(wdt->base);
> > + writel_relaxed((rst_value >> WDT_CNT_VALUE_SIZE) & WDT_CNT_VALUE_MASK,
> > + wdt->base + WDT_LOAD_HIGH);
> > + writel_relaxed((rst_value & WDT_CNT_VALUE_MASK),
> > + wdt->base + WDT_LOAD_LOW);
> > + writel_relaxed((irq_value >> WDT_CNT_VALUE_SIZE) & WDT_CNT_VALUE_MASK,
> > + wdt->base + WDT_IRQ_LOAD_HIGH);
> > + writel_relaxed(irq_value & WDT_CNT_VALUE_MASK,
> > + wdt->base + 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 + WDT_INT_RAW);
> > + if (!(val & WDT_LD_BUSY_BIT))
> > + break;
> > +
> > + cpu_relax();
> > + } while (cnt++ < WDT_LOAD_TIMEOUT_NUM);
> This loop aborts when cnt >= WDT_LOAD_TIMEOUT_NUM, then increases cnt by 1.
>
> > +
> > + if (cnt == WDT_LOAD_TIMEOUT_NUM)
>
> ... meaning this condition will never be met.
>

Yes, you are right, and I will fix it in the next version.

> > + return -EBUSY;
> > + return 0;
> > +}
> > +
> > +static void sprd_wdt_enable(struct sprd_wdt *wdt)
> > +{
> > + u32 val;
> > +
> > + clk_prepare_enable(wdt->enable);
> > + clk_prepare_enable(wdt->rtc_enable);
> > +
> > + sprd_wdt_unlock(wdt->base);
> > + val = readl_relaxed(wdt->base + WDT_CTRL);
> > + val |= WDT_NEW_VER_EN;
> > + writel_relaxed(val, wdt->base + WDT_CTRL);
> > + sprd_wdt_lock(wdt->base);
> > +}
> > +
> > +static void sprd_wdt_disable(struct sprd_wdt *wdt)
> > +{
> > + sprd_wdt_unlock(wdt->base);
> > + writel_relaxed(0x0, wdt->base + WDT_CTRL);
> > + sprd_wdt_lock(wdt->base);
> > +
> > + clk_disable(wdt->enable);
> > + clk_disable(wdt->rtc_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, wdt->rst_tmr_out * WDT_CLK,
> > + (wdt->rst_tmr_out - wdt->irq_tmr_out) * WDT_CLK);
> > + if (ret)
> > + return ret;
> > +
> > + sprd_wdt_unlock(wdt->base);
> > + val = readl_relaxed(wdt->base + WDT_CTRL);
> > + val |= WDT_CNT_EN_BIT | WDT_INT_EN_BIT | WDT_RST_EN_BIT;
> > + writel_relaxed(val, wdt->base + WDT_CTRL);
> > + sprd_wdt_lock(wdt->base);
> > +
> > + 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 + WDT_CTRL);
> > + val &= ~(WDT_CNT_EN_BIT | WDT_RST_EN_BIT | WDT_INT_EN_BIT);
> > + writel_relaxed(val, wdt->base + 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 < wdt->irq_tmr_out) {
> > + dev_err(wdd->parent, "wrong timeout value\n");
> > + return -EINVAL;
> > + }
> > +
> If there is a minimum timeout, the probe function should set min_timeout accordingly.
> This function should not have to check the range, and it should not set a range error.
>
> Also, wdd->timeout needs to be set here.
>

You are right, it needs to set wdd->timeout, and I will use pretimerout instead of irq_tmr_out.

> > + return sprd_wdt_load_value(wdt, timeout * WDT_CLK,
> > + (timeout - wdt->irq_tmr_out) * WDT_CLK);
> > +}
> > +
> > +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 / WDT_CLK;
> > +
> > + 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,
> > + .get_timeleft = sprd_wdt_get_timeleft,
> > +};
> > +
> > +static const struct watchdog_info sprd_wdt_info = {
> > + .options = WDIOF_SETTIMEOUT | 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;
> > + u32 rst_tmr_out;
> > + int ret;
> > +
> > + wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
> > + if (!wdt)
> > + return -ENOMEM;
> > +
> > + wdt_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > + if (!wdt_res) {
> > + dev_err(&pdev->dev, "failed to memory resource\n");
> > + return -ENOMEM;
> > + }
> > +
> > + wdt->base = devm_ioremap_nocache(&pdev->dev, wdt_res->start,
> > + resource_size(wdt_res));
> > + if (!wdt->base)
> > + return -ENOMEM;
> > +
> > + if (of_property_read_u32(pdev->dev.of_node, "timeout-sec",
> > + &rst_tmr_out)) {
> > + dev_err(&pdev->dev, "can't get reset timeout\n");
> > + return -EINVAL;
> > + }
>
> Please use the infrastructure to read and set this property.
>

Yes, "timeout-sec" will be read out by watchdog_init_timeout.

> > +
> > + 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) {
> > + 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->rst_tmr_out = rst_tmr_out;
> > + wdt->irq_tmr_out = rst_tmr_out - WDT_IRQ_TMROUT_OFFSET;
>
> Seems to me this is equivalent to pretimeout. Why not use the infrastructure ?
> Besides, this can currently get negative (if timeout is set to 1 or 2 seconds.
>

I will use pretimeout instead of irq_tmr_out.

> > + wdt->wdd.info = &sprd_wdt_info;
> > + wdt->wdd.ops = &sprd_wdt_ops;
> > + wdt->wdd.min_timeout = 1;
> > + wdt->wdd.max_timeout = rst_tmr_out;
> > + wdt->wdd.parent = &pdev->dev;
> > + set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
>
> Is it ? The clocks are not enabled (yet), and the start function hasn't been called.
>
> Presumably the idea is to start the watchdog unconditionally, but then it is stopped
> after being opened and closed again, so I don't really understand the logic.
>

OK, I will remove this line and I will set status bit as ACTIVE at sprd_wdt_enable.

> > + watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev);
> > +
> > + ret = watchdog_register_device(&wdt->wdd);
> > + if (ret) {
> > + dev_err(&pdev->dev, "failed to register watchdog\n");
> > + return ret;
> > + }
> > +
> > + platform_set_drvdata(pdev, wdt);
> > +
> > + sprd_wdt_enable(wdt);
> > +
>
> This is racy; at least in theory user space can open the watchdog device
> immediately after it was registered, meaning the watchdog can be enabled
> before this code is executed. Maybe that is safe, but it may as well result
> in an error or hang since the clocks are still disabled.
>
> Even more, WDOG_HW_RUNNING is set above, meaning the watchdog core will
> schedule an immediate ping (or start since there is no ping function),
> making this even more likely.
>

I understood your point, and I will fix it in next version.

> > + return 0;
> > +}
> > +
> > +static int sprd_wdt_remove(struct platform_device *pdev)
> > +{
> > + struct sprd_wdt *wdt = platform_get_drvdata(pdev);
> > +
> > + watchdog_unregister_device(&wdt->wdd);
> > +
>
> If the watchdog ws never opened, this won't stop the clocks.
>

It should add one condition api here.

> > + return 0;
> > +}
> > +
> > +static int __maybe_unused sprd_wdt_pm_suspend(struct device *dev)
> > +{
> > + struct sprd_wdt *wdt = dev_get_drvdata(dev);
> > +
> > + sprd_wdt_stop(&wdt->wdd);
>
> Why stop the watchdog if it isn't running ?
>

It should add one condition to check if watchdog is running.

> > + 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);
> > +
> > + sprd_wdt_enable(wdt);
> > + sprd_wdt_start(&wdt->wdd);
>
> So on resume the watchdog is started unconditionally, even if it was
> not running before ?
>

It should add one condition to check if watchdog has been stop.
Very appreciated for your comments.

> > +
> > + 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,
> > + .remove = sprd_wdt_remove,
> > + .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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