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)
  26 static 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  */
  32 static 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
  43 static 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
  50 static void __init picoxcell_map_io(void)
  51 {
  52         iotable_init(&io_map, 1);
  53 }
  54
  55 static 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
  61 static const char *picoxcell_dt_match[] = {
  62         "picochip,pc3x2",
  63         "picochip,pc3x3",
  64         NULL
  65 };
  66
  67 static 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
  81 DT_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,
  86 MACHINE_END