117 lines
3.7 KiB
Diff
117 lines
3.7 KiB
Diff
From 347167bd9ac2a68870064edd921f2525bd569c6d Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.org>
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Date: Mon, 16 Jul 2018 14:40:13 +0100
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Subject: [PATCH] dwc-otg: FIQ: Fix "bad mode in data abort handler"
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Create a semi-static mapping for the USB registers early in the boot
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process, before additional kernel threads are started, so all threads
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will have the mappings from the start. This avoids the need for
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data aborts to lazily update them.
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See: https://github.com/raspberrypi/linux/issues/2450
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Signed-off-by: Floris Bos <bos@je-eigen-domein.nl>
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---
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arch/arm/mach-bcm/board_bcm2835.c | 69 +++++++++++++++++++++++++++++++
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1 file changed, 69 insertions(+)
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--- a/arch/arm/mach-bcm/board_bcm2835.c
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+++ b/arch/arm/mach-bcm/board_bcm2835.c
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@@ -6,6 +6,7 @@
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#include <linux/init.h>
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#include <linux/irqchip.h>
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#include <linux/of_address.h>
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+#include <linux/of_fdt.h>
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#include <asm/system_info.h>
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#include <asm/mach/arch.h>
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@@ -13,6 +14,9 @@
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#include "platsmp.h"
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+#define BCM2835_USB_VIRT_BASE 0xf0980000
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+#define BCM2835_USB_VIRT_MPHI 0xf0006000
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+
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static void __init bcm2835_init(void)
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{
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struct device_node *np = of_find_node_by_path("/system");
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@@ -25,6 +29,70 @@ static void __init bcm2835_init(void)
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system_serial_low = val64;
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}
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+/*
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+ * We need to map registers that are going to be accessed by the FIQ
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+ * very early, before any kernel threads are spawned. Because if done
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+ * later, the mapping tables are not updated instantly but lazily upon
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+ * first access through a data abort handler. While that is fine
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+ * when executing regular kernel code, if the first access in a specific
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+ * thread happens while running FIQ code this will result in a panic.
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+ *
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+ * For more background see the following old mailing list thread:
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+ * https://www.spinics.net/lists/arm-kernel/msg325250.html
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+ */
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+static int __init bcm2835_map_usb(unsigned long node, const char *uname,
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+ int depth, void *data)
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+{
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+ struct map_desc map[2];
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+ const __be32 *reg;
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+ int len;
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+ unsigned long p2b_offset = *((unsigned long *) data);
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+
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+ if (!of_flat_dt_is_compatible(node, "brcm,bcm2708-usb"))
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+ return 0;
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+ reg = of_get_flat_dt_prop(node, "reg", &len);
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+ if (!reg || len != (sizeof(unsigned long) * 4))
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+ return 0;
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+
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+ /* Use information about the physical addresses of the
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+ * registers from the device tree, but use legacy
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+ * iotable_init() static mapping function to map them,
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+ * as ioremap() is not functional at this stage in boot.
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+ */
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+ map[0].virtual = (unsigned long) BCM2835_USB_VIRT_BASE;
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+ map[0].pfn = __phys_to_pfn(be32_to_cpu(reg[0]) - p2b_offset);
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+ map[0].length = be32_to_cpu(reg[1]);
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+ map[0].type = MT_DEVICE;
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+ map[1].virtual = (unsigned long) BCM2835_USB_VIRT_MPHI;
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+ map[1].pfn = __phys_to_pfn(be32_to_cpu(reg[2]) - p2b_offset);
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+ map[1].length = be32_to_cpu(reg[3]);
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+ map[1].type = MT_DEVICE;
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+ iotable_init(map, 2);
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+
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+ return 1;
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+}
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+
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+static void __init bcm2835_map_io(void)
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+{
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+ const __be32 *ranges;
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+ int soc, len;
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+ unsigned long p2b_offset;
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+
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+ debug_ll_io_init();
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+
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+ /* Find out how to map bus to physical address first from soc/ranges */
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+ soc = of_get_flat_dt_subnode_by_name(of_get_flat_dt_root(), "soc");
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+ if (soc < 0)
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+ return;
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+ ranges = of_get_flat_dt_prop(soc, "ranges", &len);
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+ if (!ranges || len < (sizeof(unsigned long) * 3))
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+ return;
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+ p2b_offset = be32_to_cpu(ranges[0]) - be32_to_cpu(ranges[1]);
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+
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+ /* Now search for bcm2708-usb node in device tree */
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+ of_scan_flat_dt(bcm2835_map_usb, &p2b_offset);
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+}
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+
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static const char * const bcm2835_compat[] = {
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#ifdef CONFIG_ARCH_MULTI_V6
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"brcm,bcm2835",
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@@ -37,6 +105,7 @@ static const char * const bcm2835_compat
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};
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DT_MACHINE_START(BCM2835, "BCM2835")
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+ .map_io = bcm2835_map_io,
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.init_machine = bcm2835_init,
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.dt_compat = bcm2835_compat,
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.smp = smp_ops(bcm2836_smp_ops),
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