target/linux/bcm27xx/patches-5.10/950-0071-dwc-otg-FIQ-Fix-bad-mode-in-data-abort-handler.patch

   1 From 347167bd9ac2a68870064edd921f2525bd569c6d Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.org>
   3 Date: Mon, 16 Jul 2018 14:40:13 +0100
   4 Subject: [PATCH] dwc-otg: FIQ: Fix "bad mode in data abort handler"
   5
   6 Create a semi-static mapping for the USB registers early in the boot
   7 process, before additional kernel threads are started, so all threads
   8 will have the mappings from the start. This avoids the need for
   9 data aborts to lazily update them.
  10
  11 See: https://github.com/raspberrypi/linux/issues/2450
  12
  13 Signed-off-by: Floris Bos <bos@je-eigen-domein.nl>
  14 ---
  15  arch/arm/mach-bcm/board_bcm2835.c | 69 +++++++++++++++++++++++++++++++
  16  1 file changed, 69 insertions(+)
  17
  18 --- a/arch/arm/mach-bcm/board_bcm2835.c
  19 +++ b/arch/arm/mach-bcm/board_bcm2835.c
  20 @@ -6,6 +6,7 @@
  21  #include <linux/init.h>
  22  #include <linux/irqchip.h>
  23  #include <linux/of_address.h>
  24 +#include <linux/of_fdt.h>
  25  #include <asm/system_info.h>
  26
  27  #include <asm/mach/arch.h>
  28 @@ -13,6 +14,9 @@
  29
  30  #include "platsmp.h"
  31
  32 +#define BCM2835_USB_VIRT_BASE   0xf0980000
  33 +#define BCM2835_USB_VIRT_MPHI   0xf0006000
  34 +
  35  static void __init bcm2835_init(void)
  36  {
  37         struct device_node *np = of_find_node_by_path("/system");
  38 @@ -25,6 +29,70 @@ static void __init bcm2835_init(void)
  39                 system_serial_low = val64;
  40  }
  41
  42 +/*
  43 + * We need to map registers that are going to be accessed by the FIQ
  44 + * very early, before any kernel threads are spawned. Because if done
  45 + * later, the mapping tables are not updated instantly but lazily upon
  46 + * first access through a data abort handler. While that is fine
  47 + * when executing regular kernel code, if the first access in a specific
  48 + * thread happens while running FIQ code this will result in a panic.
  49 + *
  50 + * For more background see the following old mailing list thread:
  51 + * https://www.spinics.net/lists/arm-kernel/msg325250.html
  52 + */
  53 +static int __init bcm2835_map_usb(unsigned long node, const char *uname,
  54 +                                       int depth, void *data)
  55 +{
  56 +       struct map_desc map[2];
  57 +       const __be32 *reg;
  58 +       int len;
  59 +       unsigned long p2b_offset = *((unsigned long *) data);
  60 +
  61 +       if (!of_flat_dt_is_compatible(node, "brcm,bcm2708-usb"))
  62 +               return 0;
  63 +       reg = of_get_flat_dt_prop(node, "reg", &len);
  64 +       if (!reg || len != (sizeof(unsigned long) * 4))
  65 +               return 0;
  66 +
  67 +       /* Use information about the physical addresses of the
  68 +        * registers from the device tree, but use legacy
  69 +        * iotable_init() static mapping function to map them,
  70 +        * as ioremap() is not functional at this stage in boot.
  71 +        */
  72 +       map[0].virtual = (unsigned long) BCM2835_USB_VIRT_BASE;
  73 +       map[0].pfn = __phys_to_pfn(be32_to_cpu(reg[0]) - p2b_offset);
  74 +       map[0].length = be32_to_cpu(reg[1]);
  75 +       map[0].type = MT_DEVICE;
  76 +       map[1].virtual = (unsigned long) BCM2835_USB_VIRT_MPHI;
  77 +       map[1].pfn = __phys_to_pfn(be32_to_cpu(reg[2]) - p2b_offset);
  78 +       map[1].length = be32_to_cpu(reg[3]);
  79 +       map[1].type = MT_DEVICE;
  80 +               iotable_init(map, 2);
  81 +
  82 +       return 1;
  83 +}
  84 +
  85 +static void __init bcm2835_map_io(void)
  86 +{
  87 +       const __be32 *ranges;
  88 +       int soc, len;
  89 +       unsigned long p2b_offset;
  90 +
  91 +       debug_ll_io_init();
  92 +
  93 +       /* Find out how to map bus to physical address first from soc/ranges */
  94 +       soc = of_get_flat_dt_subnode_by_name(of_get_flat_dt_root(), "soc");
  95 +       if (soc < 0)
  96 +               return;
  97 +       ranges = of_get_flat_dt_prop(soc, "ranges", &len);
  98 +       if (!ranges || len < (sizeof(unsigned long) * 3))
  99 +               return;
 100 +       p2b_offset = be32_to_cpu(ranges[0]) - be32_to_cpu(ranges[1]);
 101 +
 102 +       /* Now search for bcm2708-usb node in device tree */
 103 +       of_scan_flat_dt(bcm2835_map_usb, &p2b_offset);
 104 +}
 105 +
 106  static const char * const bcm2835_compat[] = {
 107  #ifdef CONFIG_ARCH_MULTI_V6
 108         "brcm,bcm2835",
 109 @@ -37,6 +105,7 @@ static const char * const bcm2835_compat
 110  };
 111
 112  DT_MACHINE_START(BCM2835, "BCM2835")
 113 +       .map_io = bcm2835_map_io,
 114         .init_machine = bcm2835_init,
 115         .dt_compat = bcm2835_compat,
 116         .smp = smp_ops(bcm2836_smp_ops),