1 /*
2 * Copyright (C) 2019 Repk repk@triplefau.lt
3 *
4 * SPDX-License-Identifier: BSD-3-Clause
5 * https://spdx.org/licenses
6 */
7
8 #include <inttypes.h>
9 #include <stdint.h>
10
11 #include <common/bl_common.h>
12 #include <common/debug.h>
13 #include <arch_helpers.h>
14 #include <plat/common/platform.h>
15 #include <bl31/ea_handle.h>
16
17 #define A53_SERR_INT_AXI_SLVERR_ON_EXTERNAL_ACCESS 0xbf000002
18
19 /*
20 * This source file with custom plat_ea_handler function is compiled only when
21 * building TF-A with compile option HANDLE_EA_EL3_FIRST_NS=1
22 */
plat_ea_handler(unsigned int ea_reason,uint64_t syndrome,void * cookie,void * handle,uint64_t flags)23 void plat_ea_handler(unsigned int ea_reason, uint64_t syndrome, void *cookie,
24 void *handle, uint64_t flags)
25 {
26 unsigned int level = (unsigned int)GET_EL(read_spsr_el3());
27
28 /*
29 * Asynchronous External Abort with syndrome 0xbf000002 on Cortex A53
30 * core means SError interrupt caused by AXI SLVERR on external access.
31 *
32 * In most cases this indicates a bug in U-Boot or Linux kernel driver
33 * pci-aardvark.c which implements access to A3700 PCIe config space.
34 * Driver does not wait for PCIe PIO transfer completion and try to
35 * start a new PCIe PIO transfer while previous has not finished yet.
36 * A3700 PCIe controller in this case sends SLVERR via AXI which results
37 * in a fatal Asynchronous SError interrupt on Cortex A53 CPU.
38 *
39 * Following patches fix that bug in U-Boot and Linux kernel drivers:
40 * https://source.denx.de/u-boot/u-boot/-/commit/eccbd4ad8e4e182638eafbfb87ac139c04f24a01
41 * https://git.kernel.org/stable/c/f18139966d072dab8e4398c95ce955a9742e04f7
42 *
43 * As a hacky workaround for unpatched U-Boot and Linux kernel drivers
44 * ignore all asynchronous aborts with that syndrome value received on
45 * CPU from level lower than EL3.
46 *
47 * Because these aborts are delivered on CPU asynchronously, they are
48 * imprecise and we cannot check the real reason of abort and neither
49 * who and why sent this abort. We expect that on A3700 it is always
50 * PCIe controller.
51 *
52 * Hence ignoring all aborts with this syndrome value is just a giant
53 * hack that we need only because of bugs in old U-Boot and Linux kernel
54 * versions and because it was decided that TF-A would implement this
55 * hack for U-Boot and Linux kernel it in this way. New patched U-Boot
56 * and kernel versions do not need it anymore.
57 *
58 * Links to discussion about this workaround:
59 * https://lore.kernel.org/linux-pci/20190316161243.29517-1-repk@triplefau.lt/
60 * https://lore.kernel.org/linux-pci/971be151d24312cc533989a64bd454b4@www.loen.fr/
61 * https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/1541
62 */
63 if (level < MODE_EL3 && ea_reason == ERROR_EA_ASYNC &&
64 syndrome == A53_SERR_INT_AXI_SLVERR_ON_EXTERNAL_ACCESS) {
65 ERROR_NL();
66 ERROR("Ignoring Asynchronous External Abort with"
67 " syndrome 0x%" PRIx64 " received on 0x%lx from %s\n",
68 syndrome, read_mpidr_el1(), get_el_str(level));
69 ERROR("SError interrupt: AXI SLVERR on external access\n");
70 ERROR("This indicates a bug in pci-aardvark.c driver\n");
71 ERROR("Please update U-Boot/Linux to the latest version\n");
72 ERROR_NL();
73 console_flush();
74 return;
75 }
76
77 plat_default_ea_handler(ea_reason, syndrome, cookie, handle, flags);
78 }
79
