projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| affddff6 RC |
1 | /* |
| 2 | * kmsg dumper that ensures the OPAL console fully flushes panic messages | |
| 3 | * | |
| 4 | * Author: Russell Currey <ruscur@russell.cc> | |
| 5 | * | |
| 6 | * Copyright 2015 IBM Corporation. | |
| 7 | * | |
| 8 | * This program is free software; you can redistribute it and/or modify it | |
| 9 | * under the terms of the GNU General Public License as published by the | |
| 10 | * Free Software Foundation; either version 2 of the License, or (at your | |
| 11 | * option) any later version. | |
| 12 | */ | |
| 13 | ||
| 14 | #include <linux/kmsg_dump.h> | |
| 15 | ||
| 16 | #include <asm/opal.h> | |
| 17 | #include <asm/opal-api.h> | |
| 18 | ||
| 19 | /* | |
| 20 | * Console output is controlled by OPAL firmware. The kernel regularly calls | |
| 21 | * OPAL_POLL_EVENTS, which flushes some console output. In a panic state, | |
| 22 | * however, the kernel no longer calls OPAL_POLL_EVENTS and the panic message | |
| 23 | * may not be completely printed. This function does not actually dump the | |
| 24 | * message, it just ensures that OPAL completely flushes the console buffer. | |
| 25 | */ | |
| 26 | static void force_opal_console_flush(struct kmsg_dumper *dumper, | |
| 27 | enum kmsg_dump_reason reason) | |
| 28 | { | |
| 29 | int i; | |
| 30 | ||
| 31 | /* | |
| 32 | * Outside of a panic context the pollers will continue to run, | |
| 33 | * so we don't need to do any special flushing. | |
| 34 | */ | |
| 35 | if (reason != KMSG_DUMP_PANIC) | |
| 36 | return; | |
| 37 | ||
| 38 | if (opal_check_token(OPAL_CONSOLE_FLUSH)) { | |
| 39 | opal_console_flush(); | |
| 40 | } else { | |
| 41 | /* | |
| 42 | * If OPAL_CONSOLE_FLUSH is not implemented in the firmware, | |
| 43 | * the console can still be flushed by calling the polling | |
| 44 | * function enough times to flush the buffer. We don't know | |
| 45 | * how much output still needs to be flushed, but we can be | |
| 46 | * generous since the kernel is in panic and doesn't need | |
| 47 | * to do much else. | |
| 48 | */ | |
| 49 | printk(KERN_NOTICE "opal: OPAL_CONSOLE_FLUSH missing.\n"); | |
| 50 | for (i = 0; i < 1024; i++) { | |
| 51 | opal_poll_events(NULL); | |
| 52 | } | |
| 53 | } | |
| 54 | } | |
| 55 | ||
| 56 | static struct kmsg_dumper opal_kmsg_dumper = { | |
| 57 | .dump = force_opal_console_flush | |
| 58 | }; | |
| 59 | ||
| 60 | void __init opal_kmsg_init(void) | |
| 61 | { | |
| 62 | int rc; | |
| 63 | ||
| 64 | /* Add our dumper to the list */ | |
| 65 | rc = kmsg_dump_register(&opal_kmsg_dumper); | |
| 66 | if (rc != 0) | |
| 67 | pr_err("opal: kmsg_dump_register failed; returned %d\n", rc); | |
| 68 | } |