power: Add APM X-Gene system reboot driver

Add APM X-Gene SoC system reboot driver. This driver handles only system
reboot. System shutdown is board specific and can be handled by board
driver or GPIO based shutdown driver.

Signed-off-by: Loc Ho <[e-mail]>
Signed-off-by: Feng Kan <[e-mail]>
Signed-off-by: Kumar Sankaran <[e-mail]>
Signed-off-by: Anton Vorontsov <[e-mail]>

drivers/power/reset/Kconfig

···
 	help
 	  Power off and reset support for the ARM Ltd. Versatile
 	  Express boards.
+
+config POWER_RESET_XGENE
+	bool "APM SoC X-Gene reset driver"
+	depends on ARM64
+	depends on POWER_RESET
+	help
+	  Reboot support for the APM SoC X-Gene Eval boards.

drivers/power/reset/Makefile

···
 obj-$(CONFIG_POWER_RESET_QNAP) += qnap-poweroff.o
 obj-$(CONFIG_POWER_RESET_RESTART) += restart-poweroff.o
 obj-$(CONFIG_POWER_RESET_VEXPRESS) += vexpress-poweroff.o
+obj-$(CONFIG_POWER_RESET_XGENE) += xgene-reboot.o

drivers/power/reset/xgene-reboot.c

···
+/*
+ * AppliedMicro X-Gene SoC Reboot Driver
+ *
+ * Copyright (c) 2013, Applied Micro Circuits Corporation
+ * Author: Feng Kan <[e-mail]>
+ * Author: Loc Ho <[e-mail]>
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ *
+ * This driver provides system reboot functionality for APM X-Gene SoC.
+ * For system shutdown, this is board specify. If a board designer
+ * implements GPIO shutdown, use the gpio-poweroff.c driver.
+ */
+#include <linux/io.h>
+#include <linux/of_device.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/stat.h>
+#include <linux/slab.h>
+#include <asm/system_misc.h>
+
+struct xgene_reboot_context {
+	struct platform_device *pdev;
+	void *csr;
+	u32 mask;
+};
+
+static struct xgene_reboot_context *xgene_restart_ctx;
+
+static void xgene_restart(char str, const char *cmd)
+{
+	struct xgene_reboot_context *ctx = xgene_restart_ctx;
+	unsigned long timeout;
+
+	/* Issue the reboot */
+	if (ctx)
+		writel(ctx->mask, ctx->csr);
+
+	timeout = jiffies + HZ;
+	while (time_before(jiffies, timeout))
+		cpu_relax();
+
+	dev_emerg(&ctx->pdev->dev, "Unable to restart system\n");
+}
+
+static int xgene_reboot_probe(struct platform_device *pdev)
+{
+	struct xgene_reboot_context *ctx;
+
+	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
+	if (!ctx) {
+		dev_err(&pdev->dev, "out of memory for context\n");
+		return -ENODEV;
+	}
+
+	ctx->csr = of_iomap(pdev->dev.of_node, 0);
+	if (!ctx->csr) {
+		devm_kfree(&pdev->dev, ctx);
+		dev_err(&pdev->dev, "can not map resource\n");
+		return -ENODEV;
+	}
+
+	if (of_property_read_u32(pdev->dev.of_node, "mask", &ctx->mask))
+		ctx->mask = 0xFFFFFFFF;
+
+	ctx->pdev = pdev;
+	arm_pm_restart = xgene_restart;
+	xgene_restart_ctx = ctx;
+
+	return 0;
+}
+
+static struct of_device_id xgene_reboot_of_match[] = {
+	{ .compatible = "apm,xgene-reboot" },
+	{}
+};
+
+static struct platform_driver xgene_reboot_driver = {
+	.probe = xgene_reboot_probe,
+	.driver = {
+		.name = "xgene-reboot",
+		.of_match_table = xgene_reboot_of_match,
+	},
+};
+
+static int __init xgene_reboot_init(void)
+{
+	return platform_driver_register(&xgene_reboot_driver);
+}
+device_initcall(xgene_reboot_init);