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/irq.h>
  12 #include <linux/irqchip.h>
  13 #include <linux/irqdomain.h>
  14 #include <linux/of.h>
  15 #include <linux/of_address.h>
  16 #include <linux/of_irq.h>
  17 #include <linux/of_platform.h>
  18 #include <linux/dw_apb_timer.h>
  19
  20 #include <asm/mach/arch.h>
  21 #include <asm/mach/map.h>
  22
  23 #include "common.h"
  24
  25 #define PHYS_TO_IO(x)                   (((x) & 0x00ffffff) | 0xfe000000)
  26 #define PICOXCELL_PERIPH_BASE           0x80000000
  27 #define PICOXCELL_PERIPH_LENGTH         SZ_4M
  28
  29 #define WDT_CTRL_REG_EN_MASK            (1 << 0)
  30 #define WDT_CTRL_REG_OFFS               (0x00)
  31 #define WDT_TIMEOUT_REG_OFFS            (0x04)
  32 static void __iomem *wdt_regs;
  33
  34 /*
  35  * The machine restart method can be called from an atomic context so we won't
  36  * be able to ioremap the regs then.
  37  */
  38 static void picoxcell_setup_restart(void)
  39 {
  40         struct device_node *np = of_find_compatible_node(NULL, NULL,
  41                                                          "snps,dw-apb-wdg");
  42         if (WARN(!np, "unable to setup watchdog restart"))
  43                 return;
  44
  45         wdt_regs = of_iomap(np, 0);
  46         WARN(!wdt_regs, "failed to remap watchdog regs");
  47 }
  48
  49 static struct map_desc io_map __initdata = {
  50         .virtual        = PHYS_TO_IO(PICOXCELL_PERIPH_BASE),
  51         .pfn            = __phys_to_pfn(PICOXCELL_PERIPH_BASE),
  52         .length         = PICOXCELL_PERIPH_LENGTH,
  53         .type           = MT_DEVICE,
  54 };
  55
  56 static void __init picoxcell_map_io(void)
  57 {
  58         iotable_init(&io_map, 1);
  59 }
  60
  61 static void __init picoxcell_init_machine(void)
  62 {
  63         of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
  64         picoxcell_setup_restart();
  65 }
  66
  67 static const char *picoxcell_dt_match[] = {
  68         "picochip,pc3x2",
  69         "picochip,pc3x3",
  70         NULL
  71 };
  72
  73 static void picoxcell_wdt_restart(char mode, const char *cmd)
  74 {
  75         /*
  76          * Configure the watchdog to reset with the shortest possible timeout
  77          * and give it chance to do the reset.
  78          */
  79         if (wdt_regs) {
  80                 writel_relaxed(WDT_CTRL_REG_EN_MASK, wdt_regs + WDT_CTRL_REG_OFFS);
  81                 writel_relaxed(0, wdt_regs + WDT_TIMEOUT_REG_OFFS);
  82                 /* No sleeping, possibly atomic. */
  83                 mdelay(500);
  84         }
  85 }
  86
  87 DT_MACHINE_START(PICOXCELL, "Picochip picoXcell")
  88         .map_io         = picoxcell_map_io,
  89         .nr_irqs        = NR_IRQS_LEGACY,
  90         .init_irq       = irqchip_init,
  91         .init_time      = dw_apb_timer_init,
  92         .init_machine   = picoxcell_init_machine,
  93         .dt_compat      = picoxcell_dt_match,
  94         .restart        = picoxcell_wdt_restart,
  95 MACHINE_END