[PATCH 3/4] ARM/i.MX: add support to detect the reset source

[Juergen Beisert]

Signed-off-by: Juergen Beisert <jbe at pengutronix.de>
---
 arch/arm/mach-imx/Makefile       |    1 +
 arch/arm/mach-imx/reset_source.c |   72 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 73 insertions(+)
 create mode 100644 arch/arm/mach-imx/reset_source.c

diff --git a/arch/arm/mach-imx/Makefile b/arch/arm/mach-imx/Makefile
index 89a8946..d6380ba 100644
--- a/arch/arm/mach-imx/Makefile
+++ b/arch/arm/mach-imx/Makefile
@@ -1,4 +1,5 @@
 obj-y += clocksource.o gpio.o
+obj-$(CONFIG_GLOBALVAR) += reset_source.o
 obj-$(CONFIG_ARCH_IMX1)  += speed-imx1.o  imx1.o  iomux-v1.o
 obj-$(CONFIG_ARCH_IMX25) += speed-imx25.o imx25.o iomux-v3.o
 obj-$(CONFIG_ARCH_IMX21) += speed-imx21.o imx21.o iomux-v1.o
diff --git a/arch/arm/mach-imx/reset_source.c b/arch/arm/mach-imx/reset_source.c
new file mode 100644
index 0000000..e7b2a90
--- /dev/null
+++ b/arch/arm/mach-imx/reset_source.c
@@ -0,0 +1,72 @@
+/*
+ * (C) Copyright 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.
+ */
+
+#include <common.h>
+#include <init.h>
+#include <io.h>
+#include <reset_source.h>
+#include <mach/imx-regs.h>
+
+#ifdef CONFIG_ARCH_IMX1
+#  define IMX_RESET_SRC_WDOG (1 << 1)
+#  define IMX_RESET_SRC_HRDRESET (1 << 0)
+/* let the compiler sort out useless code on this arch */
+#  define IMX_RESET_SRC_WARMSTART 0
+#  define IMX_RESET_SRC_COLDSTART 0
+#else
+  /* WRSR checked for i.MX25, i.MX27, i.MX31, i.MX35 and i.MX51 */
+# define WDOG_WRSR 0x04
+  /* valid for i.MX25, i.MX27, i.MX31, i.MX35, i.MX51 */
+#  define IMX_RESET_SRC_WARMSTART (1 << 0)
+  /* valid for i.MX25, i.MX27, i.MX31, i.MX35, i.MX51 */
+#  define IMX_RESET_SRC_WDOG (1 << 1)
+  /* valid for i.MX27, i.MX31, always '0' on i.MX25, i.MX35, i.MX51 */
+#  define IMX_RESET_SRC_HRDRESET (1 << 3)
+  /* valid for i.MX27, i.MX31, always '0' on i.MX25, i.MX35, i.MX51 */
+#  define IMX_RESET_SRC_COLDSTART (1 << 4)
+#endif
+
+static unsigned read_detection_register(void)
+{
+#ifdef CONFIG_ARCH_IMX1
+	return readl(IMX_SYSCTRL_BASE);
+#else
+	return readw(IMX_WDT_BASE + WDOG_WRSR);
+#endif
+}
+
+static int imx_detect_reset_source(void)
+{
+	unsigned reg = read_detection_register();
+
+	if (reg & IMX_RESET_SRC_COLDSTART) {
+		set_reset_source(RESET_POR);
+		return 0;
+	}
+
+	if (reg & (IMX_RESET_SRC_HRDRESET | IMX_RESET_SRC_WARMSTART)) {
+		set_reset_source(RESET_RST);
+		return 0;
+	}
+
+	if (reg & IMX_RESET_SRC_WDOG) {
+		set_reset_source(RESET_WDG);
+		return 0;
+	}
+
+	/* else keep the default 'unknown' state */
+	return 0;
+}
+
+device_initcall(imx_detect_reset_source);
-- 
1.7.10.4