power: Introduce Broadcom kona reset driver

This driver supports reset on both BCM21664 and BCM23550.
Code is being moved from arch/arm/mach-bcm/board_bcm21664.c

Signed-off-by: Chris Brand <chris.brand@broadcom.com>
Acked-By: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

MAINTAINERS

@@ -2489,6 +2489,7 @@ F:	arch/arm64/boot/dts/broadcom/
 F:	arch/arm/configs/bcm_defconfig
 F:	drivers/mmc/host/sdhci-bcm-kona.c
 F:	drivers/clocksource/bcm_kona_timer.c
+F:	drivers/power/reset/brcm-kona-reset.c
 
 BROADCOM BCM2835 ARM ARCHITECTURE
 M:	Stephen Warren <swarren@wwwdotorg.org>

drivers/power/reset/Kconfig

@@ -46,6 +46,16 @@ config POWER_RESET_AXXIA
 
 	  Say Y if you have an Axxia family SoC.
 
+config POWER_RESET_BRCMKONA
+	bool "Broadcom Kona reset driver"
+	depends on ARM || COMPILE_TEST
+	default ARCH_BCM_MOBILE
+	help
+	  This driver provides restart support for Broadcom Kona chips.
+
+	  Say Y here if you have a Broadcom Kona-based board and you wish
+	  to have restart support.
+
 config POWER_RESET_BRCMSTB
 	bool "Broadcom STB reset driver"
 	depends on ARM || MIPS || COMPILE_TEST

drivers/power/reset/Makefile

@@ -3,6 +3,7 @@ obj-$(CONFIG_POWER_RESET_AT91_POWEROFF) += at91-poweroff.o
 obj-$(CONFIG_POWER_RESET_AT91_RESET) += at91-reset.o
 obj-$(CONFIG_POWER_RESET_AT91_SAMA5D2_SHDWC) += at91-sama5d2_shdwc.o
 obj-$(CONFIG_POWER_RESET_AXXIA) += axxia-reset.o
+obj-$(CONFIG_POWER_RESET_BRCMKONA) += brcm-kona-reset.o
 obj-$(CONFIG_POWER_RESET_BRCMSTB) += brcmstb-reboot.o
 obj-$(CONFIG_POWER_RESET_GPIO) += gpio-poweroff.o
 obj-$(CONFIG_POWER_RESET_GPIO_RESTART) += gpio-restart.o

drivers/power/reset/brcm-kona-reset.c

@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2016 Broadcom
+ *
+ * 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 version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; 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_address.h>
+#include <linux/of_platform.h>
+#include <linux/reboot.h>
+
+#define RSTMGR_REG_WR_ACCESS_OFFSET	0
+#define RSTMGR_REG_CHIP_SOFT_RST_OFFSET	4
+
+#define RSTMGR_WR_PASSWORD		0xa5a5
+#define RSTMGR_WR_PASSWORD_SHIFT	8
+#define RSTMGR_WR_ACCESS_ENABLE		1
+
+static void __iomem *kona_reset_base;
+
+static int kona_reset_handler(struct notifier_block *this,
+				unsigned long mode, void *cmd)
+{
+	/*
+	 * A soft reset is triggered by writing a 0 to bit 0 of the soft reset
+	 * register. To write to that register we must first write the password
+	 * and the enable bit in the write access enable register.
+	 */
+	writel((RSTMGR_WR_PASSWORD << RSTMGR_WR_PASSWORD_SHIFT) |
+		RSTMGR_WR_ACCESS_ENABLE,
+		kona_reset_base + RSTMGR_REG_WR_ACCESS_OFFSET);
+	writel(0, kona_reset_base + RSTMGR_REG_CHIP_SOFT_RST_OFFSET);
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block kona_reset_nb = {
+	.notifier_call = kona_reset_handler,
+	.priority = 128,
+};
+
+static int kona_reset_probe(struct platform_device *pdev)
+{
+	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	kona_reset_base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(kona_reset_base))
+		return PTR_ERR(kona_reset_base);
+
+	return register_restart_handler(&kona_reset_nb);
+}
+
+static const struct of_device_id of_match[] = {
+	{ .compatible = "brcm,bcm21664-resetmgr" },
+	{},
+};
+
+static struct platform_driver bcm_kona_reset_driver = {
+	.probe = kona_reset_probe,
+	.driver = {
+		.name = "brcm-kona-reset",
+		.of_match_table = of_match,
+	},
+};
+
+builtin_platform_driver(bcm_kona_reset_driver);