LXR linux/arch/arm/mach-picoxcell/common.c

   1/*
   2 * Copyright (c) 2011 Picochip Ltd., Jamie Iles
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 *
   8 * All enquiries to support@picochip.com
   9 */
  10#include <linux/delay.h>
  11#include <linux/of.h>
  12#include <linux/of_address.h>
  13#include <linux/of_platform.h>
  14#include <linux/reboot.h>
  15
  16#include <asm/mach/arch.h>
  17#include <asm/mach/map.h>
  18
  19#define PHYS_TO_IO(x)                   (((x) & 0x00ffffff) | 0xfe000000)
  20#define PICOXCELL_PERIPH_BASE           0x80000000
  21#define PICOXCELL_PERIPH_LENGTH         SZ_4M
  22
  23#define WDT_CTRL_REG_EN_MASK            (1 << 0)
  24#define WDT_CTRL_REG_OFFS               (0x00)
  25#define WDT_TIMEOUT_REG_OFFS            (0x04)
  26static void __iomem *wdt_regs;
  27
  28/*
  29 * The machine restart method can be called from an atomic context so we won't
  30 * be able to ioremap the regs then.
  31 */
  32static void picoxcell_setup_restart(void)
  33{
  34        struct device_node *np = of_find_compatible_node(NULL, NULL,
  35                                                         "snps,dw-apb-wdg");
  36        if (WARN(!np, "unable to setup watchdog restart"))
  37                return;
  38
  39        wdt_regs = of_iomap(np, 0);
  40        WARN(!wdt_regs, "failed to remap watchdog regs");
  41}
  42
  43static struct map_desc io_map __initdata = {
  44        .virtual        = PHYS_TO_IO(PICOXCELL_PERIPH_BASE),
  45        .pfn            = __phys_to_pfn(PICOXCELL_PERIPH_BASE),
  46        .length         = PICOXCELL_PERIPH_LENGTH,
  47        .type           = MT_DEVICE,
  48};
  49
  50static void __init picoxcell_map_io(void)
  51{
  52        iotable_init(&io_map, 1);
  53}
  54
  55static void __init picoxcell_init_machine(void)
  56{
  57        of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
  58        picoxcell_setup_restart();
  59}
  60
  61static const char *picoxcell_dt_match[] = {
  62        "picochip,pc3x2",
  63        "picochip,pc3x3",
  64        NULL
  65};
  66
  67static void picoxcell_wdt_restart(enum reboot_mode mode, const char *cmd)
  68{
  69        /*
  70         * Configure the watchdog to reset with the shortest possible timeout
  71         * and give it chance to do the reset.
  72         */
  73        if (wdt_regs) {
  74                writel_relaxed(WDT_CTRL_REG_EN_MASK, wdt_regs + WDT_CTRL_REG_OFFS);
  75                writel_relaxed(0, wdt_regs + WDT_TIMEOUT_REG_OFFS);
  76                /* No sleeping, possibly atomic. */
  77                mdelay(500);
  78        }
  79}
  80
  81DT_MACHINE_START(PICOXCELL, "Picochip picoXcell")
  82        .map_io         = picoxcell_map_io,
  83        .init_machine   = picoxcell_init_machine,
  84        .dt_compat      = picoxcell_dt_match,
  85        .restart        = picoxcell_wdt_restart,
  86MACHINE_END
  87