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@@ -6,6 +6,7 @@
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* Licensed under GPLv2.
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*/
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+#include <linux/delay.h>
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#include <linux/interrupt.h>
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#include <linux/io.h>
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#include <linux/kernel.h>
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@@ -29,6 +30,7 @@ struct sama5d4_wdt {
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struct watchdog_device wdd;
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void __iomem *reg_base;
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u32 mr;
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+ unsigned long last_ping;
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};
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static int wdt_timeout = WDT_DEFAULT_TIMEOUT;
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@@ -44,11 +46,34 @@ MODULE_PARM_DESC(nowayout,
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"Watchdog cannot be stopped once started (default="
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__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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+#define wdt_enabled (!(wdt->mr & AT91_WDT_WDDIS))
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+
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#define wdt_read(wdt, field) \
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readl_relaxed((wdt)->reg_base + (field))
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-#define wdt_write(wtd, field, val) \
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- writel_relaxed((val), (wdt)->reg_base + (field))
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+/* 4 slow clock periods is 4/32768 = 122.07µs*/
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+#define WDT_DELAY usecs_to_jiffies(123)
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+
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+static void wdt_write(struct sama5d4_wdt *wdt, u32 field, u32 val)
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+{
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+ /*
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+ * WDT_CR and WDT_MR must not be modified within three slow clock
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+ * periods following a restart of the watchdog performed by a write
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+ * access in WDT_CR.
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+ */
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+ while (time_before(jiffies, wdt->last_ping + WDT_DELAY))
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+ usleep_range(30, 125);
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+ writel_relaxed(val, wdt->reg_base + field);
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+ wdt->last_ping = jiffies;
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+}
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+
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+static void wdt_write_nosleep(struct sama5d4_wdt *wdt, u32 field, u32 val)
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+{
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+ if (time_before(jiffies, wdt->last_ping + WDT_DELAY))
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+ udelay(123);
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+ writel_relaxed(val, wdt->reg_base + field);
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+ wdt->last_ping = jiffies;
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+}
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static int sama5d4_wdt_start(struct watchdog_device *wdd)
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{
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@@ -89,7 +114,16 @@ static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
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wdt->mr &= ~AT91_WDT_WDD;
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wdt->mr |= AT91_WDT_SET_WDV(value);
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wdt->mr |= AT91_WDT_SET_WDD(value);
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- wdt_write(wdt, AT91_WDT_MR, wdt->mr);
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+
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+ /*
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+ * WDDIS has to be 0 when updating WDD/WDV. The datasheet states: When
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+ * setting the WDDIS bit, and while it is set, the fields WDV and WDD
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+ * must not be modified.
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+ * If the watchdog is enabled, then the timeout can be updated. Else,
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+ * wait that the user enables it.
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+ */
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+ if (wdt_enabled)
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+ wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS);
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wdd->timeout = timeout;
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@@ -145,23 +179,21 @@ static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
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static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
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{
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- struct watchdog_device *wdd = &wdt->wdd;
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- u32 value = WDT_SEC2TICKS(wdd->timeout);
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u32 reg;
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-
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/*
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- * Because the fields WDV and WDD must not be modified when the WDDIS
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- * bit is set, so clear the WDDIS bit before writing the WDT_MR.
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+ * When booting and resuming, the bootloader may have changed the
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+ * watchdog configuration.
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+ * If the watchdog is already running, we can safely update it.
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+ * Else, we have to disable it properly.
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*/
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- reg = wdt_read(wdt, AT91_WDT_MR);
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- reg &= ~AT91_WDT_WDDIS;
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- wdt_write(wdt, AT91_WDT_MR, reg);
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-
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- wdt->mr |= AT91_WDT_SET_WDD(value);
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- wdt->mr |= AT91_WDT_SET_WDV(value);
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-
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- wdt_write(wdt, AT91_WDT_MR, wdt->mr);
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-
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+ if (wdt_enabled) {
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+ wdt_write_nosleep(wdt, AT91_WDT_MR, wdt->mr);
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+ } else {
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+ reg = wdt_read(wdt, AT91_WDT_MR);
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+ if (!(reg & AT91_WDT_WDDIS))
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+ wdt_write_nosleep(wdt, AT91_WDT_MR,
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+ reg | AT91_WDT_WDDIS);
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+ }
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return 0;
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}
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@@ -172,6 +204,7 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
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struct resource *res;
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void __iomem *regs;
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u32 irq = 0;
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+ u32 timeout;
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int ret;
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wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
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@@ -184,6 +217,7 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
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wdd->ops = &sama5d4_wdt_ops;
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wdd->min_timeout = MIN_WDT_TIMEOUT;
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wdd->max_timeout = MAX_WDT_TIMEOUT;
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+ wdt->last_ping = jiffies;
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watchdog_set_drvdata(wdd, wdt);
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@@ -221,6 +255,11 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
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return ret;
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}
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+ timeout = WDT_SEC2TICKS(wdd->timeout);
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+
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+ wdt->mr |= AT91_WDT_SET_WDD(timeout);
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+ wdt->mr |= AT91_WDT_SET_WDV(timeout);
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+
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ret = sama5d4_wdt_init(wdt);
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if (ret)
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return ret;
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@@ -263,9 +302,7 @@ static int sama5d4_wdt_resume(struct device *dev)
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{
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struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
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- wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS);
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- if (wdt->mr & AT91_WDT_WDDIS)
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- wdt_write(wdt, AT91_WDT_MR, wdt->mr);
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+ sama5d4_wdt_init(wdt);
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return 0;
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}
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