power: reset: Add AT91 reset driver

Implement the reset behaviour of the various AT91 SoCS in drivers/power/reset.

It used to be (and still is) located in arch/arm/mach-at91, and in order to
preserve bisectability is not removed yet, but every board should be converted
to use this driver instead.
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/power/reset/Kconfig

@@ -14,6 +14,14 @@ config POWER_RESET_AS3722
 	help
 	  This driver supports turning off board via a ams AS3722 power-off.
 
+config POWER_RESET_AT91_RESET
+	bool "Atmel AT91 reset driver"
+	depends on MACH_AT91
+	default SOC_AT91SAM9 || SOC_SAMA5
+	help
+	  This driver supports restart for Atmel AT91SAM9 and SAMA5
+	  SoCs
+
 config POWER_RESET_AXXIA
 	bool "LSI Axxia reset driver"
 	depends on ARCH_AXXIA

drivers/power/reset/Makefile

 obj-$(CONFIG_POWER_RESET_AS3722) += as3722-poweroff.o
+obj-$(CONFIG_POWER_RESET_AT91_RESET) += at91-reset.o
 obj-$(CONFIG_POWER_RESET_AXXIA) += axxia-reset.o
 obj-$(CONFIG_POWER_RESET_GPIO) += gpio-poweroff.o
 obj-$(CONFIG_POWER_RESET_MSM) += msm-poweroff.o

drivers/power/reset/at91-reset.c

+/*
+ * Atmel AT91 SAM9 SoCs reset code
+ *
+ * Copyright (C) 2007 Atmel Corporation.
+ * Copyright (C) BitBox Ltd 2010
+ * Copyright (C) 2011 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcosoft.com>
+ * Copyright (C) 2014 Free Electrons
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+
+#include <asm/system_misc.h>
+
+#include <mach/at91sam9_ddrsdr.h>
+#include <mach/at91sam9_sdramc.h>
+
+#define AT91_RSTC_CR	0x00		/* Reset Controller Control Register */
+#define AT91_RSTC_PROCRST	BIT(0)		/* Processor Reset */
+#define AT91_RSTC_PERRST	BIT(2)		/* Peripheral Reset */
+#define AT91_RSTC_EXTRST	BIT(3)		/* External Reset */
+#define AT91_RSTC_KEY		(0xa5 << 24)	/* KEY Password */
+
+#define AT91_RSTC_SR	0x04		/* Reset Controller Status Register */
+#define AT91_RSTC_URSTS		BIT(0)		/* User Reset Status */
+#define AT91_RSTC_RSTTYP	GENMASK(10, 8)	/* Reset Type */
+#define AT91_RSTC_NRSTL		BIT(16)		/* NRST Pin Level */
+#define AT91_RSTC_SRCMP		BIT(17)		/* Software Reset Command in Progress */
+
+#define AT91_RSTC_MR	0x08		/* Reset Controller Mode Register */
+#define AT91_RSTC_URSTEN	BIT(0)		/* User Reset Enable */
+#define AT91_RSTC_URSTIEN	BIT(4)		/* User Reset Interrupt Enable */
+#define AT91_RSTC_ERSTL		GENMASK(11, 8)	/* External Reset Length */
+
+enum reset_type {
+	RESET_TYPE_GENERAL	= 0,
+	RESET_TYPE_WAKEUP	= 1,
+	RESET_TYPE_WATCHDOG	= 2,
+	RESET_TYPE_SOFTWARE	= 3,
+	RESET_TYPE_USER		= 4,
+};
+
+static void __iomem *at91_ramc_base[2], *at91_rstc_base;
+
+/*
+* unless the SDRAM is cleanly shutdown before we hit the
+* reset register it can be left driving the data bus and
+* killing the chance of a subsequent boot from NAND
+*/
+static void at91sam9260_restart(enum reboot_mode mode, const char *cmd)
+{
+	asm volatile(
+		/* Align to cache lines */
+		".balign 32\n\t"
+
+		/* Disable SDRAM accesses */
+		"str	%2, [%0, #" __stringify(AT91_SDRAMC_TR) "]\n\t"
+
+		/* Power down SDRAM */
+		"str	%3, [%0, #" __stringify(AT91_SDRAMC_LPR) "]\n\t"
+
+		/* Reset CPU */
+		"str	%4, [%1, #" __stringify(AT91_RSTC_CR) "]\n\t"
+
+		"b	.\n\t"
+		:
+		: "r" (at91_ramc_base[0]),
+		  "r" (at91_rstc_base),
+		  "r" (1),
+		  "r" (AT91_SDRAMC_LPCB_POWER_DOWN),
+		  "r" (AT91_RSTC_KEY | AT91_RSTC_PERRST | AT91_RSTC_PROCRST));
+}
+
+static void at91sam9g45_restart(enum reboot_mode mode, const char *cmd)
+{
+	asm volatile(
+		/*
+		 * Test wether we have a second RAM controller to care
+		 * about.
+		 *
+		 * First, test that we can dereference the virtual address.
+		 */
+		"cmp	%1, #0\n\t"
+		"beq	1f\n\t"
+
+		/* Then, test that the RAM controller is enabled */
+		"ldr	r0, [%1]\n\t"
+		"cmp	r0, #0\n\t"
+
+		/* Align to cache lines */
+		".balign 32\n\t"
+
+		/* Disable SDRAM0 accesses */
+		"1:	str	%3, [%0, #" __stringify(AT91_DDRSDRC_RTR) "]\n\t"
+		/* Power down SDRAM0 */
+		"	str	%4, [%0, #" __stringify(AT91_DDRSDRC_RTR) "]\n\t"
+		/* Disable SDRAM1 accesses */
+		"	strne	%3, [%1, #" __stringify(AT91_DDRSDRC_RTR) "]\n\t"
+		/* Power down SDRAM1 */
+		"	strne	%4, [%1, #" __stringify(AT91_DDRSDRC_RTR) "]\n\t"
+		/* Reset CPU */
+		"	str	%5, [%2, #" __stringify(AT91_RSTC_CR) "]\n\t"
+
+		"	b	.\n\t"
+		:
+		: "r" (at91_ramc_base[0]),
+		  "r" (at91_ramc_base[1]),
+		  "r" (at91_rstc_base),
+		  "r" (1),
+		  "r" (AT91_DDRSDRC_LPCB_POWER_DOWN),
+		  "r" (AT91_RSTC_KEY | AT91_RSTC_PERRST | AT91_RSTC_PROCRST)
+		: "r0");
+}
+
+static void __init at91_reset_status(struct platform_device *pdev)
+{
+	u32 reg = readl(at91_rstc_base + AT91_RSTC_SR);
+	char *reason;
+
+	switch ((reg & AT91_RSTC_RSTTYP) >> 8) {
+	case RESET_TYPE_GENERAL:
+		reason = "general reset";
+		break;
+	case RESET_TYPE_WAKEUP:
+		reason = "wakeup";
+		break;
+	case RESET_TYPE_WATCHDOG:
+		reason = "watchdog reset";
+		break;
+	case RESET_TYPE_SOFTWARE:
+		reason = "software reset";
+		break;
+	case RESET_TYPE_USER:
+		reason = "user reset";
+		break;
+	default:
+		reason = "unknown reset";
+		break;
+	}
+
+	pr_info("AT91: Starting after %s\n", reason);
+}
+
+static struct of_device_id at91_ramc_of_match[] = {
+	{ .compatible = "atmel,at91sam9260-sdramc", },
+	{ .compatible = "atmel,at91sam9g45-ddramc", },
+	{ .compatible = "atmel,sama5d3-ddramc", },
+	{ /* sentinel */ }
+};
+
+static struct of_device_id at91_reset_of_match[] = {
+	{ .compatible = "atmel,at91sam9260-rstc", .data = at91sam9260_restart },
+	{ .compatible = "atmel,at91sam9g45-rstc", .data = at91sam9g45_restart },
+	{ /* sentinel */ }
+};
+
+static int at91_reset_of_probe(struct platform_device *pdev)
+{
+	const struct of_device_id *match;
+	struct device_node *np;
+	int idx = 0;
+
+	at91_rstc_base = of_iomap(pdev->dev.of_node, 0);
+	if (!at91_rstc_base) {
+		dev_err(&pdev->dev, "Could not map reset controller address\n");
+		return -ENODEV;
+	}
+
+	for_each_matching_node(np, at91_ramc_of_match) {
+		at91_ramc_base[idx] = of_iomap(np, 0);
+		if (!at91_ramc_base[idx]) {
+			dev_err(&pdev->dev, "Could not map ram controller address\n");
+			return -ENODEV;
+		}
+		idx++;
+	}
+
+	match = of_match_node(at91_reset_of_match, pdev->dev.of_node);
+	arm_pm_restart = match->data;
+
+	return 0;
+}
+
+static int at91_reset_platform_probe(struct platform_device *pdev)
+{
+	const struct platform_device_id *match;
+	struct resource *res;
+	int idx = 0;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	at91_rstc_base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(at91_rstc_base)) {
+		dev_err(&pdev->dev, "Could not map reset controller address\n");
+		return PTR_ERR(at91_rstc_base);
+	}
+
+	for (idx = 0; idx < 2; idx++) {
+		res = platform_get_resource(pdev, IORESOURCE_MEM, idx + 1 );
+		at91_ramc_base[idx] = devm_ioremap(&pdev->dev, res->start,
+						   resource_size(res));
+		if (IS_ERR(at91_ramc_base[idx])) {
+			dev_err(&pdev->dev, "Could not map ram controller address\n");
+			return PTR_ERR(at91_ramc_base[idx]);
+		}
+	}
+
+	match = platform_get_device_id(pdev);
+	arm_pm_restart = (void (*)(enum reboot_mode, const char*))
+		match->driver_data;
+
+	return 0;
+}
+
+static int at91_reset_probe(struct platform_device *pdev)
+{
+	int ret;
+
+	if (pdev->dev.of_node)
+		ret = at91_reset_of_probe(pdev);
+	else
+		ret = at91_reset_platform_probe(pdev);
+
+	if (ret)
+		return ret;
+
+	at91_reset_status(pdev);
+
+	return 0;
+}
+
+static struct platform_device_id at91_reset_plat_match[] = {
+	{ "at91-sam9260-reset", (unsigned long)at91sam9260_restart },
+	{ "at91-sam9g45-reset", (unsigned long)at91sam9g45_restart },
+	{ /* sentinel */ }
+};
+
+static struct platform_driver at91_reset_driver = {
+	.probe = at91_reset_probe,
+	.driver = {
+		.name = "at91-reset",
+		.of_match_table = at91_reset_of_match,
+	},
+	.id_table = at91_reset_plat_match,
+};
+module_platform_driver(at91_reset_driver);