sysreset: add syscon-reboot driver

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 <noltari@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/sysreset/Kconfig

@@ -23,4 +23,12 @@ config SYSRESET_PSCI
 	  must be running on your system.
 
 endif
+
+config SYSRESET_SYSCON
+	bool "Enable support for mfd syscon reboot driver"
+	select REGMAP
+	select SYSCON
+	help
+	  Reboot support for generic SYSCON mapped register reset.
+
 endmenu

drivers/sysreset/Makefile

@@ -6,6 +6,7 @@
 
 obj-$(CONFIG_SYSRESET) += sysreset-uclass.o
 obj-$(CONFIG_SYSRESET_PSCI) += sysreset_psci.o
+obj-$(CONFIG_SYSRESET_SYSCON) += sysreset_syscon.o
 
 ifndef CONFIG_SPL_BUILD
 obj-$(CONFIG_ROCKCHIP_RK3036) += sysreset_rk3036.o

drivers/sysreset/sysreset_syscon.c

@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2017 Álvaro Fernández Rojas <noltari@gmail.com>
+ *
+ * Derived from linux/drivers/power/reset/syscon-reboot.c:
+ *	Copyright (C) 2013, Applied Micro Circuits Corporation
+ *	Author: Feng Kan <fkan@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,
+};