arch/arm/mach-bcm2835/bcm2835.c

   1 /*
   2  * Copyright (C) 2010 Broadcom
   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 as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #include <linux/delay.h>
  16 #include <linux/init.h>
  17 #include <linux/irqchip/bcm2835.h>
  18 #include <linux/of_address.h>
  19 #include <linux/of_platform.h>
  20 #include <linux/clk/bcm2835.h>
  21 #include <linux/clocksource.h>
  22
  23 #include <asm/mach/arch.h>
  24 #include <asm/mach/map.h>
  25
  26 #include <mach/bcm2835_soc.h>
  27
  28 #define PM_RSTC                         0x1c
  29 #define PM_WDOG                         0x24
  30
  31 #define PM_PASSWORD                     0x5a000000
  32 #define PM_RSTC_WRCFG_MASK              0x00000030
  33 #define PM_RSTC_WRCFG_FULL_RESET        0x00000020
  34
  35 static void __iomem *wdt_regs;
  36
  37 /*
  38  * The machine restart method can be called from an atomic context so we won't
  39  * be able to ioremap the regs then.
  40  */
  41 static void bcm2835_setup_restart(void)
  42 {
  43         struct device_node *np = of_find_compatible_node(NULL, NULL,
  44                                                 "brcm,bcm2835-pm-wdt");
  45         if (WARN(!np, "unable to setup watchdog restart"))
  46                 return;
  47
  48         wdt_regs = of_iomap(np, 0);
  49         WARN(!wdt_regs, "failed to remap watchdog regs");
  50 }
  51
  52 static void bcm2835_restart(char mode, const char *cmd)
  53 {
  54         u32 val;
  55
  56         if (!wdt_regs)
  57                 return;
  58
  59         /* use a timeout of 10 ticks (~150us) */
  60         writel_relaxed(10 | PM_PASSWORD, wdt_regs + PM_WDOG);
  61         val = readl_relaxed(wdt_regs + PM_RSTC);
  62         val &= ~PM_RSTC_WRCFG_MASK;
  63         val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
  64         writel_relaxed(val, wdt_regs + PM_RSTC);
  65
  66         /* No sleeping, possibly atomic. */
  67         mdelay(1);
  68 }
  69
  70 static struct map_desc io_map __initdata = {
  71         .virtual = BCM2835_PERIPH_VIRT,
  72         .pfn = __phys_to_pfn(BCM2835_PERIPH_PHYS),
  73         .length = BCM2835_PERIPH_SIZE,
  74         .type = MT_DEVICE
  75 };
  76
  77 static void __init bcm2835_map_io(void)
  78 {
  79         iotable_init(&io_map, 1);
  80 }
  81
  82 static void __init bcm2835_init(void)
  83 {
  84         int ret;
  85
  86         bcm2835_setup_restart();
  87         bcm2835_init_clocks();
  88
  89         ret = of_platform_populate(NULL, of_default_bus_match_table, NULL,
  90                                    NULL);
  91         if (ret) {
  92                 pr_err("of_platform_populate failed: %d\n", ret);
  93                 BUG();
  94         }
  95 }
  96
  97 static const char * const bcm2835_compat[] = {
  98         "brcm,bcm2835",
  99         NULL
 100 };
 101
 102 DT_MACHINE_START(BCM2835, "BCM2835")
 103         .map_io = bcm2835_map_io,
 104         .init_irq = bcm2835_init_irq,
 105         .handle_irq = bcm2835_handle_irq,
 106         .init_machine = bcm2835_init,
 107         .init_time = clocksource_of_init,
 108         .restart = bcm2835_restart,
 109         .dt_compat = bcm2835_compat
 110 MACHINE_END