Add a watchdog driver for ARM MPcore processors.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -324,6 +324,13 @@ config KS8695_WATCHDOG
 	  Watchdog timer embedded into KS8695 processor. This will reboot your
 	  system when the timeout is reached.
 
+config MPCORE_WATCHDOG
+	tristate "MPcore watchdog"
+	depends on HAVE_ARM_TWD
+	select WATCHDOG_CORE
+	help
+	  Watchdog timer embedded into the MPcore system
+
 config HAVE_S3C2410_WATCHDOG
 	bool
 	help
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -47,6 +47,7 @@ obj-$(CONFIG_21285_WATCHDOG) += wdt285.o
 obj-$(CONFIG_977_WATCHDOG) += wdt977.o
 obj-$(CONFIG_IXP4XX_WATCHDOG) += ixp4xx_wdt.o
 obj-$(CONFIG_KS8695_WATCHDOG) += ks8695_wdt.o
+obj-$(CONFIG_MPCORE_WATCHDOG) += mpcore_wdt.o
 obj-$(CONFIG_S3C2410_WATCHDOG) += s3c2410_wdt.o
 obj-$(CONFIG_SA1100_WATCHDOG) += sa1100_wdt.o
 obj-$(CONFIG_SAMA5D4_WATCHDOG) += sama5d4_wdt.o
--- /dev/null
+++ b/drivers/watchdog/mpcore_wdt.c
@@ -0,0 +1,118 @@
+/*
+ * Watchdog driver for ARM MPcore
+ *
+ * Copyright (C) 2017 Felix Fietkau <nbd@nbd.name>
+ */
+
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/watchdog.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <asm/smp_twd.h>
+
+static void __iomem *wdt_base;
+static int wdt_timeout = 60;
+
+static int mpcore_wdt_keepalive(struct watchdog_device *wdd)
+{
+	static int perturb;
+	u32 count;
+
+	count = (twd_timer_get_rate() / 256) * wdt_timeout;
+
+	/* Reload register needs a different value on each refresh */
+	count += perturb;
+	perturb = !perturb;
+
+	iowrite32(count, wdt_base + TWD_WDOG_LOAD);
+
+	return 0;
+}
+
+static int mpcore_wdt_start(struct watchdog_device *wdd)
+{
+	mpcore_wdt_keepalive(wdd);
+
+	/* prescale = 256, mode = 1, enable = 1 */
+	iowrite32(0x0000FF09, wdt_base + TWD_WDOG_CONTROL);
+
+	return 0;
+}
+
+static int mpcore_wdt_stop(struct watchdog_device *wdd)
+{
+	iowrite32(0x12345678, wdt_base + TWD_WDOG_DISABLE);
+	iowrite32(0x87654321, wdt_base + TWD_WDOG_DISABLE);
+	iowrite32(0x0, wdt_base + TWD_WDOG_CONTROL);
+
+	return 0;
+}
+
+static int mpcore_wdt_set_timeout(struct watchdog_device *wdd,
+				 unsigned int timeout)
+{
+	mpcore_wdt_stop(wdd);
+	wdt_timeout = timeout;
+	mpcore_wdt_start(wdd);
+
+	return 0;
+}
+
+static const struct watchdog_info mpcore_wdt_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+	.identity = "MPcore Watchdog",
+};
+
+static const struct watchdog_ops mpcore_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = mpcore_wdt_start,
+	.stop  = mpcore_wdt_stop,
+	.ping  = mpcore_wdt_keepalive,
+	.set_timeout = mpcore_wdt_set_timeout,
+};
+
+static struct watchdog_device mpcore_wdt = {
+	.info = &mpcore_wdt_info,
+	.ops = &mpcore_wdt_ops,
+	.min_timeout = 1,
+	.max_timeout = 65535,
+};
+
+static int mpcore_wdt_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	unsigned long rate = twd_timer_get_rate();
+
+	pr_info("MPCore WD init. clockrate: %u prescaler: %u countrate: %u timeout: %us\n", rate, 256, rate / 256, wdt_timeout);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	wdt_base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(wdt_base))
+		return PTR_ERR(wdt_base);
+
+	watchdog_register_device(&mpcore_wdt);
+	return 0;
+}
+
+static int mpcore_wdt_remove(struct platform_device *dev)
+{
+	watchdog_unregister_device(&mpcore_wdt);
+	return 0;
+}
+
+static struct platform_driver mpcore_wdt_driver = {
+	.probe		= mpcore_wdt_probe,
+	.remove		= mpcore_wdt_remove,
+	.driver		= {
+		.name	= "mpcore_wdt",
+	},
+};
+
+module_platform_driver(mpcore_wdt_driver);
+MODULE_AUTHOR("Felix Fietkau <nbd@nbd.name>");
+MODULE_LICENSE("GPL");
--- a/arch/arm/include/asm/smp_twd.h
+++ b/arch/arm/include/asm/smp_twd.h
@@ -33,5 +33,6 @@ struct twd_local_timer name __initdata =
 };
 
 int twd_local_timer_register(struct twd_local_timer *);
+unsigned long twd_timer_get_rate(void);
 
 #endif
--- a/arch/arm/kernel/smp_twd.c
+++ b/arch/arm/kernel/smp_twd.c
@@ -15,6 +15,7 @@
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/err.h>
+#include <linux/export.h>
 #include <linux/smp.h>
 #include <linux/jiffies.h>
 #include <linux/clockchips.h>
@@ -380,6 +381,14 @@ int __init twd_local_timer_register(stru
 	return twd_local_timer_common_register(NULL);
 }
 
+/* Needed by mpcore_wdt */
+unsigned long twd_timer_get_rate(void)
+{
+	return twd_timer_rate;
+}
+EXPORT_SYMBOL_GPL(twd_timer_get_rate);
+
+
 #ifdef CONFIG_OF
 static int __init twd_local_timer_of_register(struct device_node *np)
 {