1bfc36894SJoel Stanley /* 2bfc36894SJoel Stanley * PowerNV OPAL in-memory console interface 3bfc36894SJoel Stanley * 4bfc36894SJoel Stanley * Copyright 2014 IBM Corp. 5bfc36894SJoel Stanley * 6bfc36894SJoel Stanley * This program is free software; you can redistribute it and/or 7bfc36894SJoel Stanley * modify it under the terms of the GNU General Public License 8bfc36894SJoel Stanley * as published by the Free Software Foundation; either version 9bfc36894SJoel Stanley * 2 of the License, or (at your option) any later version. 10bfc36894SJoel Stanley */ 11bfc36894SJoel Stanley 12bfc36894SJoel Stanley #include <asm/io.h> 13bfc36894SJoel Stanley #include <asm/opal.h> 14bfc36894SJoel Stanley #include <linux/debugfs.h> 15bfc36894SJoel Stanley #include <linux/of.h> 16bfc36894SJoel Stanley #include <linux/types.h> 17bfc36894SJoel Stanley #include <asm/barrier.h> 18bfc36894SJoel Stanley 19bfc36894SJoel Stanley /* OPAL in-memory console. Defined in OPAL source at core/console.c */ 20bfc36894SJoel Stanley struct memcons { 21bfc36894SJoel Stanley __be64 magic; 22bfc36894SJoel Stanley #define MEMCONS_MAGIC 0x6630696567726173L 23bfc36894SJoel Stanley __be64 obuf_phys; 24bfc36894SJoel Stanley __be64 ibuf_phys; 25bfc36894SJoel Stanley __be32 obuf_size; 26bfc36894SJoel Stanley __be32 ibuf_size; 27bfc36894SJoel Stanley __be32 out_pos; 28bfc36894SJoel Stanley #define MEMCONS_OUT_POS_WRAP 0x80000000u 29bfc36894SJoel Stanley #define MEMCONS_OUT_POS_MASK 0x00ffffffu 30bfc36894SJoel Stanley __be32 in_prod; 31bfc36894SJoel Stanley __be32 in_cons; 32bfc36894SJoel Stanley }; 33bfc36894SJoel Stanley 34bfc36894SJoel Stanley static ssize_t opal_msglog_read(struct file *file, struct kobject *kobj, 35bfc36894SJoel Stanley struct bin_attribute *bin_attr, char *to, 36bfc36894SJoel Stanley loff_t pos, size_t count) 37bfc36894SJoel Stanley { 38bfc36894SJoel Stanley struct memcons *mc = bin_attr->private; 39bfc36894SJoel Stanley const char *conbuf; 40bfc36894SJoel Stanley size_t ret, first_read = 0; 41bfc36894SJoel Stanley uint32_t out_pos, avail; 42bfc36894SJoel Stanley 43bfc36894SJoel Stanley if (!mc) 44bfc36894SJoel Stanley return -ENODEV; 45bfc36894SJoel Stanley 46bfc36894SJoel Stanley out_pos = be32_to_cpu(ACCESS_ONCE(mc->out_pos)); 47bfc36894SJoel Stanley 48bfc36894SJoel Stanley /* Now we've read out_pos, put a barrier in before reading the new 49bfc36894SJoel Stanley * data it points to in conbuf. */ 50bfc36894SJoel Stanley smp_rmb(); 51bfc36894SJoel Stanley 52bfc36894SJoel Stanley conbuf = phys_to_virt(be64_to_cpu(mc->obuf_phys)); 53bfc36894SJoel Stanley 54bfc36894SJoel Stanley /* When the buffer has wrapped, read from the out_pos marker to the end 55bfc36894SJoel Stanley * of the buffer, and then read the remaining data as in the un-wrapped 56bfc36894SJoel Stanley * case. */ 57bfc36894SJoel Stanley if (out_pos & MEMCONS_OUT_POS_WRAP) { 58bfc36894SJoel Stanley 59bfc36894SJoel Stanley out_pos &= MEMCONS_OUT_POS_MASK; 60bfc36894SJoel Stanley avail = be32_to_cpu(mc->obuf_size) - out_pos; 61bfc36894SJoel Stanley 62bfc36894SJoel Stanley ret = memory_read_from_buffer(to, count, &pos, 63bfc36894SJoel Stanley conbuf + out_pos, avail); 64bfc36894SJoel Stanley 65bfc36894SJoel Stanley if (ret < 0) 66bfc36894SJoel Stanley goto out; 67bfc36894SJoel Stanley 68bfc36894SJoel Stanley first_read = ret; 69bfc36894SJoel Stanley to += first_read; 70bfc36894SJoel Stanley count -= first_read; 71bfc36894SJoel Stanley pos -= avail; 72bfc36894SJoel Stanley } 73bfc36894SJoel Stanley 74bfc36894SJoel Stanley /* Sanity check. The firmware should not do this to us. */ 75bfc36894SJoel Stanley if (out_pos > be32_to_cpu(mc->obuf_size)) { 76bfc36894SJoel Stanley pr_err("OPAL: memory console corruption. Aborting read.\n"); 77bfc36894SJoel Stanley return -EINVAL; 78bfc36894SJoel Stanley } 79bfc36894SJoel Stanley 80bfc36894SJoel Stanley ret = memory_read_from_buffer(to, count, &pos, conbuf, out_pos); 81bfc36894SJoel Stanley 82bfc36894SJoel Stanley if (ret < 0) 83bfc36894SJoel Stanley goto out; 84bfc36894SJoel Stanley 85bfc36894SJoel Stanley ret += first_read; 86bfc36894SJoel Stanley out: 87bfc36894SJoel Stanley return ret; 88bfc36894SJoel Stanley } 89bfc36894SJoel Stanley 90bfc36894SJoel Stanley static struct bin_attribute opal_msglog_attr = { 91bfc36894SJoel Stanley .attr = {.name = "msglog", .mode = 0444}, 92bfc36894SJoel Stanley .read = opal_msglog_read 93bfc36894SJoel Stanley }; 94bfc36894SJoel Stanley 95bfc36894SJoel Stanley void __init opal_msglog_init(void) 96bfc36894SJoel Stanley { 97bfc36894SJoel Stanley u64 mcaddr; 98bfc36894SJoel Stanley struct memcons *mc; 99bfc36894SJoel Stanley 100bfc36894SJoel Stanley if (of_property_read_u64(opal_node, "ibm,opal-memcons", &mcaddr)) { 101bfc36894SJoel Stanley pr_warn("OPAL: Property ibm,opal-memcons not found, no message log\n"); 102bfc36894SJoel Stanley return; 103bfc36894SJoel Stanley } 104bfc36894SJoel Stanley 105bfc36894SJoel Stanley mc = phys_to_virt(mcaddr); 106bfc36894SJoel Stanley if (!mc) { 107bfc36894SJoel Stanley pr_warn("OPAL: memory console address is invalid\n"); 108bfc36894SJoel Stanley return; 109bfc36894SJoel Stanley } 110bfc36894SJoel Stanley 111bfc36894SJoel Stanley if (be64_to_cpu(mc->magic) != MEMCONS_MAGIC) { 112bfc36894SJoel Stanley pr_warn("OPAL: memory console version is invalid\n"); 113bfc36894SJoel Stanley return; 114bfc36894SJoel Stanley } 115bfc36894SJoel Stanley 116bfc36894SJoel Stanley opal_msglog_attr.private = mc; 117bfc36894SJoel Stanley 118bfc36894SJoel Stanley if (sysfs_create_bin_file(opal_kobj, &opal_msglog_attr) != 0) 119bfc36894SJoel Stanley pr_warn("OPAL: sysfs file creation failed\n"); 120bfc36894SJoel Stanley } 121