Add a new sysreset driver based on linux/drivers/power/reset/syscon-reboot.c,
which provides a generic driver for platforms that only require writing a mask
to a regmap offset.

Signed-off-by: Álvaro Fernández Rojas <nolt...@gmail.com>
---
 v3: Introduce changes suggested by Simon Glass:
  - Add missing driver description.
  - Alphabetically order includes.
  - Add priv struct to store regmap during probe.
  - Cosmetic fixes.
 v2: No changes

 drivers/sysreset/Kconfig           |  8 ++++
 drivers/sysreset/Makefile          |  1 +
 drivers/sysreset/sysreset_syscon.c | 76 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 85 insertions(+)
 create mode 100644 drivers/sysreset/sysreset_syscon.c

diff --git a/drivers/sysreset/Kconfig b/drivers/sysreset/Kconfig
index 05a37b9..ad3e71e 100644
--- a/drivers/sysreset/Kconfig
+++ b/drivers/sysreset/Kconfig
@@ -13,4 +13,12 @@ config SYSRESET
          to effect a reset. The uclass will try all available drivers when
          reset_walk() is called.
 
+config SYSRESET_SYSCON
+       bool "Enable support for mfd syscon reboot driver"
+       depends on SYSRESET
+       select REGMAP
+       select SYSCON
+       help
+         Reboot support for generic SYSCON mapped register reset.
+
 endmenu
diff --git a/drivers/sysreset/Makefile b/drivers/sysreset/Makefile
index 49b8bb6..1205f47 100644
--- a/drivers/sysreset/Makefile
+++ b/drivers/sysreset/Makefile
@@ -18,3 +18,4 @@ obj-$(CONFIG_ARCH_SNAPDRAGON) += sysreset_snapdragon.o
 obj-$(CONFIG_ARCH_STI) += sysreset_sti.o
 obj-$(CONFIG_TARGET_XTFPGA) += sysreset_xtfpga.o
 obj-$(CONFIG_ARCH_ASPEED) += sysreset_ast.o
+obj-$(CONFIG_SYSRESET_SYSCON) += sysreset_syscon.o
diff --git a/drivers/sysreset/sysreset_syscon.c 
b/drivers/sysreset/sysreset_syscon.c
new file mode 100644
index 0000000..adfddb4
--- /dev/null
+++ b/drivers/sysreset/sysreset_syscon.c
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2017 Álvaro Fernández Rojas <nolt...@gmail.com>
+ *
+ * Derived from linux/drivers/power/reset/syscon-reboot.c:
+ *     Copyright (C) 2013, Applied Micro Circuits Corporation
+ *     Author: Feng Kan <f...@apm.com>
+ *
+ * SPDX-License-Identifier:    GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <regmap.h>
+#include <sysreset.h>
+#include <syscon.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct syscon_reboot_priv {
+       struct regmap *regmap;
+       unsigned int offset;
+       unsigned int mask;
+};
+
+static int syscon_reboot_request(struct udevice *dev, enum sysreset_t type)
+{
+       struct syscon_reboot_priv *priv = dev_get_priv(dev);
+
+       regmap_write(priv->regmap, priv->offset, priv->mask);
+
+       return -EINPROGRESS;
+}
+
+static struct sysreset_ops syscon_reboot_ops = {
+       .request = syscon_reboot_request,
+};
+
+int syscon_reboot_probe(struct udevice *dev)
+{
+       struct udevice *syscon;
+       struct syscon_reboot_priv *priv = dev_get_priv(dev);
+       int err;
+
+       err = uclass_get_device_by_phandle(UCLASS_SYSCON, dev,
+                                          "regmap", &syscon);
+       if (err) {
+               error("unable to find syscon device\n");
+               return err;
+       }
+
+       priv->regmap = syscon_get_regmap(syscon);
+       if (!priv->regmap) {
+               error("unable to find regmap\n");
+               return -ENODEV;
+       }
+
+       priv->offset = fdtdec_get_uint(gd->fdt_blob, dev_of_offset(dev), 
"offset", 0);
+       priv->mask = fdtdec_get_uint(gd->fdt_blob, dev_of_offset(dev), "mask", 
0);
+
+       return 0;
+}
+
+static const struct udevice_id syscon_reboot_ids[] = {
+       { .compatible = "syscon-reboot" },
+       { /* sentinel */ }
+};
+
+U_BOOT_DRIVER(syscon_reboot) = {
+       .name = "syscon_reboot",
+       .id = UCLASS_SYSRESET,
+       .of_match = syscon_reboot_ids,
+       .probe = syscon_reboot_probe,
+       .priv_auto_alloc_size = sizeof(struct syscon_reboot_priv),
+       .ops = &syscon_reboot_ops,
+};
-- 
2.1.4

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