power: reset: Add generic SYSCON register mapped reset

Add a generic SYSCON register mapped reset mechanism.

Signed-off-by: Feng Kan <fkan@apm.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

3 files changed, 102 insertions, 0 deletions

diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index a178e9c50a20..addb26afae5a 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -118,3 +118,8 @@ config POWER_RESET_KEYSTONE
         help
           Reboot support for the KEYSTONE SoCs.
 
+config POWER_RESET_SYSCON
+        bool "Generic SYSCON regmap reset driver"
+        depends on POWER_RESET && MFD_SYSCON && OF
+        help
+          Reboot support for generic SYSCON mapped register reset.
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index ab8cd348a099..61ead2773331 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -13,3 +13,4 @@ obj-$(CONFIG_POWER_RESET_ST) += st-poweroff.o
 obj-$(CONFIG_POWER_RESET_VEXPRESS) += vexpress-poweroff.o
 obj-$(CONFIG_POWER_RESET_XGENE) += xgene-reboot.o
 obj-$(CONFIG_POWER_RESET_KEYSTONE) += keystone-reset.o
+obj-$(CONFIG_POWER_RESET_SYSCON) += syscon-reboot.o
diff --git a/drivers/power/reset/syscon-reboot.c b/drivers/power/reset/syscon-reboot.c
new file mode 100644
index 000000000000..948e0ee32a4d
--- /dev/null
+++ b/drivers/power/reset/syscon-reboot.c
@@ -0,0 +1,96 @@
+/*
+ * Generic Syscon Reboot Driver
+ *
+ * Copyright (c) 2013, Applied Micro Circuits Corporation
+ * Author: Feng Kan <fkan@apm.com>
+ *
+ * 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 <linux/io.h>
+#include <linux/of_device.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/notifier.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+#include <linux/reboot.h>
+
+struct syscon_reboot_context {
+        struct regmap *map;
+        u32 offset;
+        u32 mask;
+        struct notifier_block restart_handler;
+};
+
+static struct syscon_reboot_context *syscon_reboot_ctx;
+
+static int syscon_restart_handle(struct notifier_block *this,
+                                        unsigned long mode, void *cmd)
+{
+        struct syscon_reboot_context *ctx = syscon_reboot_ctx;
+        unsigned long timeout;
+
+        /* Issue the reboot */
+        if (ctx->map)
+                regmap_write(ctx->map, ctx->offset, ctx->mask);
+
+        timeout = jiffies + HZ;
+        while (time_before(jiffies, timeout))
+                cpu_relax();
+
+        pr_emerg("Unable to restart system\n");
+        return NOTIFY_DONE;
+}
+
+static int syscon_reboot_probe(struct platform_device *pdev)
+{
+        struct syscon_reboot_context *ctx;
+        struct device *dev = &pdev->dev;
+        int err;
+
+        ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
+        if (!ctx)
+                return -ENOMEM;
+
+        ctx->map = syscon_regmap_lookup_by_phandle(dev->of_node, "regmap");
+        if (IS_ERR(ctx->map))
+                return PTR_ERR(ctx->map);
+
+        if (of_property_read_u32(pdev->dev.of_node, "offset", &ctx->offset))
+                return -EINVAL;
+
+        if (of_property_read_u32(pdev->dev.of_node, "mask", &ctx->mask))
+                return -EINVAL;
+
+        ctx->restart_handler.notifier_call = syscon_restart_handle;
+        ctx->restart_handler.priority = 128;
+        err = register_restart_handler(&ctx->restart_handler);
+        if (err)
+                dev_err(dev, "can't register restart notifier (err=%d)\n", err);
+
+        syscon_reboot_ctx = ctx;
+
+        return 0;
+}
+
+static struct of_device_id syscon_reboot_of_match[] = {
+        { .compatible = "syscon-reboot" },
+        {}
+};
+
+static struct platform_driver syscon_reboot_driver = {
+        .probe = syscon_reboot_probe,
+        .driver = {
+                .name = "syscon-reboot",
+                .of_match_table = syscon_reboot_of_match,
+        },
+};
+module_platform_driver(syscon_reboot_driver);