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