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
  15 #include <asm/mach/arch.h>
  16 #include <asm/mach/map.h>
  17
  18 #define PHYS_TO_IO(x)                   (((x) & 0x00ffffff) | 0xfe000000)
  19 #define PICOXCELL_PERIPH_BASE           0x80000000
  20 #define PICOXCELL_PERIPH_LENGTH         SZ_4M
  21
  22 #define WDT_CTRL_REG_EN_MASK            (1 << 0)
  23 #define WDT_CTRL_REG_OFFS               (0x00)
  24 #define WDT_TIMEOUT_REG_OFFS            (0x04)
  25 static void __iomem *wdt_regs;
  26
  27 /*
  28  * The machine restart method can be called from an atomic context so we won't
  29  * be able to ioremap the regs then.
  30  */
  31 static void picoxcell_setup_restart(void)
  32 {
  33         struct device_node *np = of_find_compatible_node(NULL, NULL,
  34                                                          "snps,dw-apb-wdg");
  35         if (WARN(!np, "unable to setup watchdog restart"))
  36                 return;
  37
  38         wdt_regs = of_iomap(np, 0);
  39         WARN(!wdt_regs, "failed to remap watchdog regs");
  40 }
  41
  42 static struct map_desc io_map __initdata = {
  43         .virtual        = PHYS_TO_IO(PICOXCELL_PERIPH_BASE),
  44         .pfn            = __phys_to_pfn(PICOXCELL_PERIPH_BASE),
  45         .length         = PICOXCELL_PERIPH_LENGTH,
  46         .type           = MT_DEVICE,
  47 };
  48
  49 static void __init picoxcell_map_io(void)
  50 {
  51         iotable_init(&io_map, 1);
  52 }
  53
  54 static void __init picoxcell_init_machine(void)
  55 {
  56         of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
  57         picoxcell_setup_restart();
  58 }
  59
  60 static const char *picoxcell_dt_match[] = {
  61         "picochip,pc3x2",
  62         "picochip,pc3x3",
  63         NULL
  64 };
  65
  66 static void picoxcell_wdt_restart(char mode, const char *cmd)
  67 {
  68         /*
  69          * Configure the watchdog to reset with the shortest possible timeout
  70          * and give it chance to do the reset.
  71          */
  72         if (wdt_regs) {
  73                 writel_relaxed(WDT_CTRL_REG_EN_MASK, wdt_regs + WDT_CTRL_REG_OFFS);
  74                 writel_relaxed(0, wdt_regs + WDT_TIMEOUT_REG_OFFS);
  75                 /* No sleeping, possibly atomic. */
  76                 mdelay(500);
  77         }
  78 }
  79
  80 DT_MACHINE_START(PICOXCELL, "Picochip picoXcell")
  81         .map_io         = picoxcell_map_io,
  82         .init_machine   = picoxcell_init_machine,
  83         .dt_compat      = picoxcell_dt_match,
  84         .restart        = picoxcell_wdt_restart,
  85 MACHINE_END