Some Renesas SoCs do not have a reset register and the only way to do a SW
controlled reset is to use the watchdog timer. Additionally, since all the
WDT timeout options are so quick, a system reset is about the only thing
it's good for.
Signed-off-by: Chris Brandt <chris.brandt@xxxxxxxxxxx>
---
drivers/power/reset/Kconfig | 9 ++++
drivers/power/reset/Makefile | 1 +
drivers/power/reset/renesas-reset.c | 103 ++++++++++++++++++++++++++++++++++++
3 files changed, 113 insertions(+)
create mode 100644 drivers/power/reset/renesas-reset.c
diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index b8caccc..e3100c9 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -130,6 +130,15 @@ config POWER_RESET_QNAP
Say Y if you have a QNAP NAS.
+config POWER_RESET_RENESAS
+ tristate "Renesas WDT reset driver"
+ depends on ARCH_RENESAS || COMPILE_TEST
+ depends on HAS_IOMEM
+ help
+ Reboot support for Renesas SoCs with WDT reset.
+ Some Renesas SoCs do not have a reset register and the only way
+ to do a SW controlled reset is to use the watchdog timer.
+
config POWER_RESET_RESTART
bool "Restart power-off driver"
help
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index 11dae3b..a78a56c 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_POWER_RESET_MSM) += msm-poweroff.o
obj-$(CONFIG_POWER_RESET_PIIX4_POWEROFF) += piix4-poweroff.o
obj-$(CONFIG_POWER_RESET_LTC2952) += ltc2952-poweroff.o
obj-$(CONFIG_POWER_RESET_QNAP) += qnap-poweroff.o
+obj-$(CONFIG_POWER_RESET_RENESAS) += renesas-reset.o
obj-$(CONFIG_POWER_RESET_RESTART) += restart-poweroff.o
obj-$(CONFIG_POWER_RESET_ST) += st-poweroff.o
obj-$(CONFIG_POWER_RESET_VERSATILE) += arm-versatile-reboot.o
diff --git a/drivers/power/reset/renesas-reset.c b/drivers/power/reset/renesas-reset.c
new file mode 100644
index 0000000..dede029
--- /dev/null
+++ b/drivers/power/reset/renesas-reset.c
@@ -0,0 +1,103 @@
+/*
+ * Renesas WDT Reset Driver
+ *
+ * Copyright (C) 2017 Renesas Electronics America, Inc.
+ * Copyright (C) 2017 Chris Brandt
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * based on rmobile-reset.c
+ *
+ */
+
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/printk.h>
+#include <linux/reboot.h>
+
+/* Watchdog Timer Registers */
+#define WTCSR 0
+#define WTCNT 2
+#define WRCSR 4
+
+static void __iomem *base;
+
+static int wdt_reset_handler(struct notifier_block *this,
+ unsigned long mode, void *cmd)
+{
+ pr_debug("%s %lu\n", __func__, mode);
+
+ /* Dummy read (must read WRCSR:WOVF at least once before clearing) */
+ readw(base + WRCSR);
+
+ writew(0xA500, base + WRCSR); /* Clear WOVF */
+ writew(0x5A5F, base + WRCSR); /* Reset Enable */
+ writew(0x5A00, base + WTCNT); /* Counter to 00 */
+ writew(0xA578, base + WTCSR); /* Start timer */
+
+ /* Wait for WDT overflow */
+ while (1)
+ ;
+
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block wdt_reset_nb = {
+ .notifier_call = wdt_reset_handler,
+ .priority = 192,
+};
+
+static int wdt_reset_probe(struct platform_device *pdev)
+{
+ int error;
+
+ base = of_iomap(pdev->dev.of_node, 0);
+ if (!base)
+ return -ENODEV;
+
+ error = register_restart_handler(&wdt_reset_nb);
+ if (error) {
+ dev_err(&pdev->dev,
+ "cannot register restart handler (err=%d)\n", error);
+ goto fail_unmap;
+ }
+
+ return 0;
+
+fail_unmap:
+ iounmap(base);
+ return error;
+}
+
+static int wdt_reset_remove(struct platform_device *pdev)
+{
+ unregister_restart_handler(&wdt_reset_nb);
+ iounmap(base);
+ return 0;
+}
+
+static const struct of_device_id wdt_reset_of_match[] = {
+ { .compatible = "renesas,wdt-reset", },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, wdt_reset_of_match);
+
+static struct platform_driver wdt_reset_driver = {
+ .probe = wdt_reset_probe,
+ .remove = wdt_reset_remove,
+ .driver = {
+ .name = "wdt_reset",
+ .of_match_table = wdt_reset_of_match,
+ },
+};
+
+module_platform_driver(wdt_reset_driver);
+
+MODULE_DESCRIPTION("Renesas WDT Reset Driver");
+MODULE_AUTHOR("Chris Brandt <chris.brandt@xxxxxxxxxxx>");
+MODULE_LICENSE("GPL v2");
--
2.10.1
