Re: [PATCH v3 2/2] watchdog: Add Spreadtrum watchdog driver
From: Guenter Roeck
Date: Fri Oct 27 2017 - 01:23:51 EST
On 10/26/2017 07:28 PM, Eric Long wrote:
This patch adds the watchdog driver for Spreadtrum SC9860 platform.
Signed-off-by: Eric Long <eric.long@xxxxxxxxxxxxxx>
---
Change 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 | 415 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 424 insertions(+)
create mode 100644 drivers/watchdog/sprd_wdt.c
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index c722cbf..4a77e17 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 support watchdog timer embedded
+ into the Spreadtrum system.
Maybe better "supported by" instead of "embedded into". Or at least
"embedded in".
+
# 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..5fc3dde
--- /dev/null
+++ b/drivers/watchdog/sprd_wdt.c
@@ -0,0 +1,415 @@
+/*
+ * 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/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 equale to 32768 counter steps */
equal ?
+#define SPRD_WDT_CNT_STEP 32768
+
+#define SPRD_WDT_UNLOCK_KEY 0xe551
+#define SPRD_WDT_MIN_TIMROUT 3
TIMROUT ot TIMEOUT ?
+#define SPRD_WDT_MAX_TIMEOUT 60
Is that really the maximum supported timeout ? Seems a bit low.
Shouldn't it be something like (U32_MAX / SPRD_WDT_CNT_STEP) ?
+
+#define SPRD_WDT_CNT_HIGH_VALUE 16
Maybe name it "SPRD_WDT_CNT_HIGH_SHIFT". It is not really a value,
it is a shift.
+#define SPRD_WDT_LOW_VALUE_MASK GENMASK(15, 0)
+#define SPRD_WDT_CNT_VALUE_MAX GENMASK(31, 0)
Does this mask serve a useful purpose ?
+#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_VALUE;
+ 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_VALUE) &
+ 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_VALUE) &
+ 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(struct sprd_wdt *wdt)
+{
+ 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->pretimeout)
+ return 0;
This is inconsistent. pretimeout == 0 is accepted until it is set
to a non-zero value once, then 0 is no longer accepted. pretimeout==0
should reflect "pretimeout disabled". If that is not possible you
need to set some non-0 default value in the probe function.
+ if (new_pretimeout <= wdd->min_timeout)
+ return -EINVAL;
Why is pretimeout == wdd->min_timeout invalid ?
+
+ 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,
Just wondering - no heartbeat function ? Having to load the timer
values for each heartbeat is expensive.
+};
+
+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);
+ if (!wdt_res) {
+ dev_err(&pdev->dev, "failed to memory resource\n");
+ return -ENOMEM;
+ }
Unnecessary error check and message. devm_ioremap_resource()
returns an error if res is NULL.
+
+ wdt->base = devm_ioremap_resource(&pdev->dev, wdt_res);
+ if (IS_ERR(wdt->base))
Move the error message to here.
+ 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) {
+ 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_TIMROUT;
+ wdt->wdd.max_timeout = SPRD_WDT_MAX_TIMEOUT;
+
You might want to set wdt->wdd.timeout to a default value.
+ ret = sprd_wdt_enable(wdt);
+ if (ret) {
+ dev_err(&pdev->dev, "failed to enable wdt\n");
+ return ret;
+ }
+
This needs a matching sprd_wdt_disable() call in the remove function.
Best way to handle this would be to add devm_add_action() here.
+ watchdog_set_nowayout(&wdt->wdd, WATCHDOG_NOWAYOUT);
+ watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev);
+
+ ret = watchdog_register_device(&wdt->wdd);
Unfortunately this doesn't work. It leaves interrupts enabled
after the watchdog device is removed in sprd_wdt_remove(),
but the driver will be gone. I would suggest to use
devm_watchdog_register_device() and reorder calls to request
the interrupt after registering the watchdog device. Then you
can drop the remove function entirely.
+ 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 sprd_wdt_remove(struct platform_device *pdev)
+{
+ struct sprd_wdt *wdt = platform_get_drvdata(pdev);
+
+ watchdog_unregister_device(&wdt->wdd);
+
+ if (sprd_wdt_is_running(wdt))
+ dev_crit(&pdev->dev, "Device removed: Expect reboot!\n");
+ 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);
Are you sure you only want to disable the clocks if the watchdog was active ?
That seems to be a bit inconsistent.
+ }
+
+ 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;
+
+ if (watchdog_active(wdd)) {
+ ret = sprd_wdt_enable(wdt);
+ if (ret)
+ return ret;
+ ret = sprd_wdt_start(&wdt->wdd);
+ if (ret) {
+ sprd_wdt_disable(wdt);
+ return ret;
+ }
This can leave the system in an inconsistent state. Sometimes the wdt may be
disabled, sometimes not.
+ }
+
+ 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@xxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Spreadtrum Watchdog Timer Controller Driver");
+MODULE_LICENSE("GPL v2");