[PATCH 1/2] watchdog: qcom: support pre-timeout when the bark irq is available

[Jorge Ramirez-Ortiz]

Use the bark interrupt as the pre-timeout notifier whenever this
interrupt is available.

By default, the pretimeout notification shall occur one second earlier
than the timeout.

Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-or...@linaro.org>
---
 drivers/watchdog/qcom-wdt.c | 70 ++++++++++++++++++++++++++++++++++---
 1 file changed, 65 insertions(+), 5 deletions(-)

diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c
index 7be7f87be28f..935c78a882a3 100644
--- a/drivers/watchdog/qcom-wdt.c
+++ b/drivers/watchdog/qcom-wdt.c
@@ -1,8 +1,10 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /* Copyright (c) 2014, The Linux Foundation. All rights reserved.
  */
+#include <linux/bits.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
+#include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -19,6 +21,9 @@ enum wdt_reg {
        WDT_BITE_TIME,
 };
 
+#define QCOM_WDT_ENABLE                BIT(0)
+#define QCOM_WDT_ENABLE_IRQ    BIT(1)
+
 static const u32 reg_offset_data_apcs_tmr[] = {
        [WDT_RST] = 0x38,
        [WDT_EN] = 0x40,
@@ -54,15 +59,35 @@ struct qcom_wdt *to_qcom_wdt(struct watchdog_device *wdd)
        return container_of(wdd, struct qcom_wdt, wdd);
 }
 
+static inline int qcom_get_enable(struct watchdog_device *wdd)
+{
+       int enable = QCOM_WDT_ENABLE;
+
+       if (wdd->pretimeout)
+               enable |= QCOM_WDT_ENABLE_IRQ;
+
+       return enable;
+}
+
+static irqreturn_t qcom_wdt_isr(int irq, void *arg)
+{
+       struct watchdog_device *wdd = arg;
+
+       watchdog_notify_pretimeout(wdd);
+
+       return IRQ_HANDLED;
+}
+
 static int qcom_wdt_start(struct watchdog_device *wdd)
 {
        struct qcom_wdt *wdt = to_qcom_wdt(wdd);
+       unsigned int bark = wdd->timeout - wdd->pretimeout;
 
        writel(0, wdt_addr(wdt, WDT_EN));
        writel(1, wdt_addr(wdt, WDT_RST));
-       writel(wdd->timeout * wdt->rate, wdt_addr(wdt, WDT_BARK_TIME));
+       writel(bark * wdt->rate, wdt_addr(wdt, WDT_BARK_TIME));
        writel(wdd->timeout * wdt->rate, wdt_addr(wdt, WDT_BITE_TIME));
-       writel(1, wdt_addr(wdt, WDT_EN));
+       writel(qcom_get_enable(wdd), wdt_addr(wdt, WDT_EN));
        return 0;
 }
 
@@ -89,6 +114,13 @@ static int qcom_wdt_set_timeout(struct watchdog_device *wdd,
        return qcom_wdt_start(wdd);
 }
 
+static int qcom_wdt_set_pretimeout(struct watchdog_device *wdd,
+                                  unsigned int timeout)
+{
+       wdd->pretimeout = timeout;
+       return qcom_wdt_start(wdd);
+}
+
 static int qcom_wdt_restart(struct watchdog_device *wdd, unsigned long action,
                            void *data)
 {
@@ -105,7 +137,7 @@ static int qcom_wdt_restart(struct watchdog_device *wdd, 
unsigned long action,
        writel(1, wdt_addr(wdt, WDT_RST));
        writel(timeout, wdt_addr(wdt, WDT_BARK_TIME));
        writel(timeout, wdt_addr(wdt, WDT_BITE_TIME));
-       writel(1, wdt_addr(wdt, WDT_EN));
+       writel(QCOM_WDT_ENABLE, wdt_addr(wdt, WDT_EN));
 
        /*
         * Actually make sure the above sequence hits hardware before sleeping.
@@ -121,6 +153,7 @@ static const struct watchdog_ops qcom_wdt_ops = {
        .stop           = qcom_wdt_stop,
        .ping           = qcom_wdt_ping,
        .set_timeout    = qcom_wdt_set_timeout,
+       .set_pretimeout = qcom_wdt_set_pretimeout,
        .restart        = qcom_wdt_restart,
        .owner          = THIS_MODULE,
 };
@@ -133,6 +166,15 @@ static const struct watchdog_info qcom_wdt_info = {
        .identity       = KBUILD_MODNAME,
 };
 
+static const struct watchdog_info qcom_wdt_pt_info = {
+       .options        = WDIOF_KEEPALIVEPING
+                       | WDIOF_MAGICCLOSE
+                       | WDIOF_SETTIMEOUT
+                       | WDIOF_PRETIMEOUT
+                       | WDIOF_CARDRESET,
+       .identity       = KBUILD_MODNAME,
+};
+
 static void qcom_clk_disable_unprepare(void *data)
 {
        clk_disable_unprepare(data);
@@ -146,7 +188,7 @@ static int qcom_wdt_probe(struct platform_device *pdev)
        struct device_node *np = dev->of_node;
        const u32 *regs;
        u32 percpu_offset;
-       int ret;
+       int irq, ret;
 
        regs = of_device_get_match_data(dev);
        if (!regs) {
@@ -204,7 +246,25 @@ static int qcom_wdt_probe(struct platform_device *pdev)
                return -EINVAL;
        }
 
-       wdt->wdd.info = &qcom_wdt_info;
+       /* check if there is pretimeout support */
+       irq = platform_get_irq(pdev, 0);
+       if (irq > 0) {
+               ret = devm_request_irq(dev, irq, qcom_wdt_isr,
+                                      IRQF_TRIGGER_RISING,
+                                      "wdt_bark", &wdt->wdd);
+               if (ret)
+                       return ret;
+
+               wdt->wdd.info = &qcom_wdt_pt_info;
+               wdt->wdd.pretimeout = 1;
+       } else {
+               if (irq == -EPROBE_DEFER)
+                       return -EPROBE_DEFER;
+
+               wdt->wdd.info = &qcom_wdt_info;
+               wdt->wdd.pretimeout = 0;
+       }
+
        wdt->wdd.ops = &qcom_wdt_ops;
        wdt->wdd.min_timeout = 1;
        wdt->wdd.max_timeout = 0x10000000U / wdt->rate;
-- 
2.23.0