[PATCH 2/2] ARM/MXS: add a watchdog driver for i.MX28

[Juergen Beisert]

Signed-off-by: Juergen Beisert <jbe at pengutronix.de>
---
 drivers/watchdog/Kconfig  |    7 +++
 drivers/watchdog/Makefile |    1 +
 drivers/watchdog/im28wd.c |  121 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 129 insertions(+)
 create mode 100644 drivers/watchdog/im28wd.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index b5970c9..b1a73c0 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -7,4 +7,11 @@ if WATCHDOG
 config WATCHDOG_CORE
 	bool
 
+config WATCHDOG_MXS28
+	bool "i.MX28"
+	depends on ARCH_IMX28
+	select WATCHDOG_CORE
+	help
+	  Add support for watchdog management for the i.MX28 SoC.
+
 endif
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 7a446d7..b0d4d2a 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_WATCHDOG_CORE) += wd_core.o
+obj-$(CONFIG_WATCHDOG_MXS28) += im28wd.o
diff --git a/drivers/watchdog/im28wd.c b/drivers/watchdog/im28wd.c
new file mode 100644
index 0000000..b1c4809
--- /dev/null
+++ b/drivers/watchdog/im28wd.c
@@ -0,0 +1,121 @@
+/*
+ * (c) 2012 Juergen Beisert <kernel at pengutronix.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * Note: this driver works for the i.MX28 SoC. It might work for the
+ * i.MX23 Soc as well, but is not tested yet.
+ */
+
+#include <common.h>
+#include <init.h>
+#include <io.h>
+#include <errno.h>
+#include <malloc.h>
+
+#define MXS_RTC_CTRL 0x0
+#define MXS_RTC_SET_ADDR 0x4
+#define MXS_RTC_CLR_ADDR 0x8
+# define MXS_RTC_CTRL_WATCHDOGEN (1 << 4)
+
+#define MXS_RTC_STAT 0x10
+# define MXS_RTC_STAT_WD_PRESENT (1 << 29)
+
+#define MXS_RTC_WATCHDOG 0x50
+
+#define MXS_RTC_PERSISTENT0 0x60
+/* dubious meaning from inside the SoC's firmware ROM */
+# define MXS_RTC_PERSISTENT0_EXT_RST (1 << 21)
+/* dubious meaning from inside the SoC's firmware ROM */
+# define MXS_RTC_PERSISTENT0_THM_RST (1 << 20)
+
+#define MXS_RTC_PERSISTENT1 0x70
+/* dubious meaning from inside the SoC's firmware ROM */
+# define MXS_RTC_PERSISTENT1_FORCE_UPDATER (1 << 31)
+
+#define MXS_RTC_DEBUG 0xc0
+
+#define WDOG_TICK_RATE 1000 /* the watchdog uses a 1 kHz clock rate */
+
+struct imx28_wd {
+	void __iomem *regs;
+	u32 timeout;
+};
+
+static struct imx28_wd *wd;
+
+/* note: 'timeout' in clock ticks */
+static void imx28_wd_set_timeout(const struct imx28_wd *p, unsigned timeout)
+{
+	void __iomem *base;
+
+	if (timeout) {
+		writel(timeout, p->regs + MXS_RTC_WATCHDOG);
+		base = p->regs + MXS_RTC_SET_ADDR;
+	} else {
+		base = p->regs + MXS_RTC_CLR_ADDR;
+	}
+	writel(MXS_RTC_CTRL_WATCHDOGEN, base + MXS_RTC_CTRL);
+	writel(MXS_RTC_PERSISTENT1_FORCE_UPDATER, base + MXS_RTC_PERSISTENT1);
+}
+
+/* note: 'timeout' in [seconds] */
+int watchdog_set_timeout(unsigned timeout)
+{
+	if (timeout > (ULONG_MAX / WDOG_TICK_RATE))
+		return -EINVAL;
+
+	imx28_wd_set_timeout(wd, timeout * WDOG_TICK_RATE);
+	return 0;
+}
+EXPORT_SYMBOL(watchdog_set_timeout);
+
+static int imx28_wd_probe(struct device_d *dev)
+{
+	struct imx28_wd *priv;
+
+	priv = xzalloc(sizeof(struct imx28_wd));
+	priv->regs = dev_request_mem_region(dev, 0);
+	priv->timeout = 20;
+	dev->priv = priv;
+	wd = priv;
+
+	if (!(readl(priv->regs + MXS_RTC_STAT) & MXS_RTC_STAT_WD_PRESENT)) {
+		free(priv);
+		return -ENODEV;
+	}
+
+	/* disable the debug feature to ensure a working WD */
+	writel(0x00000000, priv->regs + MXS_RTC_DEBUG);
+
+	return 0;
+}
+
+static void imx28_wd_remove(struct device_d *dev)
+{
+	struct imx28_wd *priv= dev->priv;
+	wd = NULL;
+	free(priv);
+}
+
+static struct driver_d imx28_wd_driver = {
+	.name   = "im28wd",
+	.probe  = imx28_wd_probe,
+	.remove = imx28_wd_remove,
+};
+
+static int imx28_wd_init(void)
+{
+	register_driver(&imx28_wd_driver);
+	return 0;
+}
+
+device_initcall(imx28_wd_init);
-- 
1.7.10