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 #if !ENABLE_BACKTRACE 20 static const char *get_el_str(unsigned int el) 21 { 22 if (el == MODE_EL3) { 23 return "EL3"; 24 } else if (el == MODE_EL2) { 25 return "EL2"; 26 } 27 return "S-EL1"; 28 } 29 #endif /* !ENABLE_BACKTRACE */ 30 31 /* 32 * This source file with custom plat_ea_handler function is compiled only when 33 * building TF-A with compile option HANDLE_EA_EL3_FIRST=1 34 */ 35 void plat_ea_handler(unsigned int ea_reason, uint64_t syndrome, void *cookie, 36 void *handle, uint64_t flags) 37 { 38 unsigned int level = (unsigned int)GET_EL(read_spsr_el3()); 39 40 /* 41 * Asynchronous External Abort with syndrome 0xbf000002 on Cortex A53 42 * core means SError interrupt caused by AXI SLVERR on external access. 43 * 44 * In most cases this indicates a bug in U-Boot or Linux kernel driver 45 * pci-aardvark.c which implements access to A3700 PCIe config space. 46 * Driver does not wait for PCIe PIO transfer completion and try to 47 * start a new PCIe PIO transfer while previous has not finished yet. 48 * A3700 PCIe controller in this case sends SLVERR via AXI which results 49 * in a fatal Asynchronous SError interrupt on Cortex A53 CPU. 50 * 51 * Following patches fix that bug in U-Boot and Linux kernel drivers: 52 * https://source.denx.de/u-boot/u-boot/-/commit/eccbd4ad8e4e182638eafbfb87ac139c04f24a01 53 * https://git.kernel.org/stable/c/f18139966d072dab8e4398c95ce955a9742e04f7 54 * 55 * As a hacky workaround for unpatched U-Boot and Linux kernel drivers 56 * ignore all asynchronous aborts with that syndrome value received on 57 * CPU from level lower than EL3. 58 * 59 * Because these aborts are delivered on CPU asynchronously, they are 60 * imprecise and we cannot check the real reason of abort and neither 61 * who and why sent this abort. We expect that on A3700 it is always 62 * PCIe controller. 63 * 64 * Hence ignoring all aborts with this syndrome value is just a giant 65 * hack that we need only because of bugs in old U-Boot and Linux kernel 66 * versions and because it was decided that TF-A would implement this 67 * hack for U-Boot and Linux kernel it in this way. New patched U-Boot 68 * and kernel versions do not need it anymore. 69 * 70 * Links to discussion about this workaround: 71 * https://lore.kernel.org/linux-pci/20190316161243.29517-1-repk@triplefau.lt/ 72 * https://lore.kernel.org/linux-pci/971be151d24312cc533989a64bd454b4@www.loen.fr/ 73 * https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/1541 74 */ 75 if (level < MODE_EL3 && ea_reason == ERROR_EA_ASYNC && 76 syndrome == A53_SERR_INT_AXI_SLVERR_ON_EXTERNAL_ACCESS) { 77 ERROR_NL(); 78 ERROR("Ignoring Asynchronous External Abort with" 79 " syndrome 0x%" PRIx64 " received on 0x%lx from %s\n", 80 syndrome, read_mpidr_el1(), get_el_str(level)); 81 ERROR("SError interrupt: AXI SLVERR on external access\n"); 82 ERROR("This indicates a bug in pci-aardvark.c driver\n"); 83 ERROR("Please update U-Boot/Linux to the latest version\n"); 84 ERROR_NL(); 85 console_flush(); 86 return; 87 } 88 89 plat_default_ea_handler(ea_reason, syndrome, cookie, handle, flags); 90 } 91