text: /*
   * Atmel AT91 SAM9 & SAMA5 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/clk.h>
  #include <linux/io.h>
  #include <linux/module.h>
  #include <linux/of_address.h>
  #include <linux/platform_device.h>
  #include <linux/reboot.h>
  
  #include <soc/at91/at91sam9_ddrsdr.h>
  #include <soc/at91/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,
  	RESET_TYPE_CPU_FAIL	= 6,
  	RESET_TYPE_XTAL_FAIL	= 7,
  	RESET_TYPE_ULP2		= 8,
  };
  
  static void __iomem *at91_ramc_base[2], *at91_rstc_base;
  static struct clk *sclk;
  
  /*
  * 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 int at91sam9260_restart(struct notifier_block *this, unsigned long mode,
  			       void *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" cpu_to_le32(AT91_SDRAMC_LPCB_POWER_DOWN),
  		  "r" cpu_to_le32(AT91_RSTC_KEY | AT91_RSTC_PERRST | AT91_RSTC_PROCRST));
  
  	return NOTIFY_DONE;
  }
  
  static int at91sam9g45_restart(struct notifier_block *this, unsigned long mode,
  			       void *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_LPR) "]\n\t"
  		/* Disable SDRAM1 accesses */
  		"	strne	%3, [%1, #" __stringify(AT91_DDRSDRC_RTR) "]\n\t"
  		/* Power down SDRAM1 */
  		"	strne	%4, [%1, #" __stringify(AT91_DDRSDRC_LPR) "]\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" cpu_to_le32(AT91_DDRSDRC_LPCB_POWER_DOWN),
  		  "r" cpu_to_le32(AT91_RSTC_KEY | AT91_RSTC_PERRST | AT91_RSTC_PROCRST)
  		: "r0");
  
  	return NOTIFY_DONE;
  }
  
  static int sama5d3_restart(struct notifier_block *this, unsigned long mode,
  			   void *cmd)
  {
  	writel(cpu_to_le32(AT91_RSTC_KEY | AT91_RSTC_PERRST | AT91_RSTC_PROCRST),
  	       at91_rstc_base);
  
  	return NOTIFY_DONE;
  }
  
  static int samx7_restart(struct notifier_block *this, unsigned long mode,
  			 void *cmd)
  {
  	writel(cpu_to_le32(AT91_RSTC_KEY | AT91_RSTC_PROCRST),
  	       at91_rstc_base);
  
  	return NOTIFY_DONE;
  }
  
  static void __init at91_reset_status(struct platform_device *pdev)
  {
  	const char *reason;
  	u32 reg = readl(at91_rstc_base + AT91_RSTC_SR);
  
  	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;
  	case RESET_TYPE_CPU_FAIL:
  		reason = "CPU clock failure detection";
  		break;
  	case RESET_TYPE_XTAL_FAIL:
  		reason = "32.768 kHz crystal failure detection";
  		break;
  	case RESET_TYPE_ULP2:
  		reason = "ULP2 reset";
  		break;
  	default:
  		reason = "unknown reset";
  		break;
  	}
  
  	dev_info(&pdev->dev, "Starting after %s\n", reason);
  }
  
  static const struct of_device_id at91_ramc_of_match[] = {
  	{ .compatible = "atmel,at91sam9260-sdramc", },
  	{ .compatible = "atmel,at91sam9g45-ddramc", },
  	{ /* sentinel */ }
  };
  
  static const struct of_device_id at91_reset_of_match[] = {
  	{ .compatible = "atmel,at91sam9260-rstc", .data = at91sam9260_restart },
  	{ .compatible = "atmel,at91sam9g45-rstc", .data = at91sam9g45_restart },
  	{ .compatible = "atmel,sama5d3-rstc", .data = sama5d3_restart },
  	{ .compatible = "atmel,samx7-rstc", .data = samx7_restart },
  	{ .compatible = "microchip,sam9x60-rstc", .data = samx7_restart },
  	{ /* sentinel */ }
  };
  MODULE_DEVICE_TABLE(of, at91_reset_of_match);
  
  static struct notifier_block at91_restart_nb = {
  	.priority = 192,
  };
  
  static int __init at91_reset_probe(struct platform_device *pdev)
  {
  	const struct of_device_id *match;
  	struct device_node *np;
  	int ret, 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;
  	}
  
  	if (!of_device_is_compatible(pdev->dev.of_node, "atmel,sama5d3-rstc")) {
  		/* we need to shutdown the ddr controller, so get ramc base */
  		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");
  				of_node_put(np);
  				return -ENODEV;
  			}
  			idx++;
  		}
  	}
  
  	match = of_match_node(at91_reset_of_match, pdev->dev.of_node);
  	at91_restart_nb.notifier_call = match->data;
  
  	sclk = devm_clk_get(&pdev->dev, NULL);
  	if (IS_ERR(sclk))
  		return PTR_ERR(sclk);
  
  	ret = clk_prepare_enable(sclk);
  	if (ret) {
  		dev_err(&pdev->dev, "Could not enable slow clock\n");
  		return ret;
  	}
  
  	ret = register_restart_handler(&at91_restart_nb);
  	if (ret) {
  		clk_disable_unprepare(sclk);
  		return ret;
  	}
  
  	at91_reset_status(pdev);
  
  	return 0;
  }
  
  static int __exit at91_reset_remove(struct platform_device *pdev)
  {
  	unregister_restart_handler(&at91_restart_nb);
  	clk_disable_unprepare(sclk);
  
  	return 0;
  }
  
  static struct platform_driver at91_reset_driver = {
  	.remove = __exit_p(at91_reset_remove),
  	.driver = {
  		.name = "at91-reset",
  		.of_match_table = at91_reset_of_match,
  	},
  };
  module_platform_driver_probe(at91_reset_driver, at91_reset_probe);
  
  MODULE_AUTHOR("Atmel Corporation");
  MODULE_DESCRIPTION("Reset driver for Atmel SoCs");
  MODULE_LICENSE("GPL v2");
  