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alistair23-linux/arch/arm/mach-bcm/bcm_5301x.c

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/*
* Broadcom BCM470X / BCM5301X ARM platform code.
*
* Copyright 2013 Hauke Mehrtens <hauke@hauke-m.de>
*
* Licensed under the GNU/GPL. See COPYING for details.
*/
#include <linux/of_platform.h>
#include <asm/hardware/cache-l2x0.h>
#include <asm/mach/arch.h>
#include <asm/siginfo.h>
#include <asm/signal.h>
#define FSR_EXTERNAL (1 << 12)
#define FSR_READ (0 << 10)
#define FSR_IMPRECISE 0x0406
ARM: BCM5301X: workaround suppress fault Without this patch I am getting a unhandled fault exception like this one after "Freeing unused kernel memory": Freeing unused kernel memory: 1260K (c02c1000 - c03fc000) Unhandled fault: imprecise external abort (0x1c06) at 0xb6f89005 Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000007 The address which is here 0xb6f89005 changes from boot to boot, with a new build the changes are bigger. With kernel 3.10 I have also seen this fault at different places in the boot process, but starting with 3.11 they are always occurring after the "Freeing unused kernel memory" message. I never was able to completely boot to userspace without this handler. The abort code is constant 0x1c06. This fault just happens once in the boot process I have never seen it happing twice or more. I also tried changing the CPSR.A bit to 0 in init_early, with this code like Afzal suggested, but that did not change anything: asm volatile("mrs r12, cpsr\n" "bic r12, r12, #0x00000100\n" "msr cpsr_c, r12" ::: "r12", "cc", "memory"); Disabling the L2 cache by building with CONFIG_CACHE_L2X0 unset did not help. This workaround was copied from the vendor code including most of the comments. It says it they think this is caused by the CFE boot loader used on this device. I do not have any access to any datasheet or errata document to check this. Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Christian Daudt <bcm@fixthebug.org> Signed-off-by: Matt Porter <mporter@linaro.org>
2014-02-03 16:01:46 -07:00
static const char *const bcm5301x_dt_compat[] __initconst = {
"brcm,bcm4708",
NULL,
};
static int bcm5301x_abort_handler(unsigned long addr, unsigned int fsr,
struct pt_regs *regs)
{
/*
* We want to ignore aborts forwarded from the PCIe bus that are
* expected and shouldn't really be passed by the PCIe controller.
* The biggest disadvantage is the same FSR code may be reported when
* reading non-existing APB register and we shouldn't ignore that.
*/
if (fsr == (FSR_EXTERNAL | FSR_READ | FSR_IMPRECISE))
return 0;
return 1;
}
static void __init bcm5301x_init_early(void)
{
hook_fault_code(16 + 6, bcm5301x_abort_handler, SIGBUS, BUS_OBJERR,
"imprecise external abort");
}
DT_MACHINE_START(BCM5301X, "BCM5301X")
.l2c_aux_val = 0,
.l2c_aux_mask = ~0,
.dt_compat = bcm5301x_dt_compat,
.init_early = bcm5301x_init_early,
MACHINE_END