1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * PowerNV OPAL in-memory console interface 4 * 5 * Copyright 2014 IBM Corp. 6 */ 7 8 #include <asm/io.h> 9 #include <asm/opal.h> 10 #include <linux/debugfs.h> 11 #include <linux/of.h> 12 #include <linux/types.h> 13 #include <asm/barrier.h> 14 15 #include "powernv.h" 16 17 /* OPAL in-memory console. Defined in OPAL source at core/console.c */ 18 struct memcons { 19 __be64 magic; 20 #define MEMCONS_MAGIC 0x6630696567726173L 21 __be64 obuf_phys; 22 __be64 ibuf_phys; 23 __be32 obuf_size; 24 __be32 ibuf_size; 25 __be32 out_pos; 26 #define MEMCONS_OUT_POS_WRAP 0x80000000u 27 #define MEMCONS_OUT_POS_MASK 0x00ffffffu 28 __be32 in_prod; 29 __be32 in_cons; 30 }; 31 32 static struct memcons *opal_memcons = NULL; 33 34 ssize_t memcons_copy(struct memcons *mc, char *to, loff_t pos, size_t count) 35 { 36 const char *conbuf; 37 ssize_t ret; 38 size_t first_read = 0; 39 uint32_t out_pos, avail; 40 41 if (!mc) 42 return -ENODEV; 43 44 out_pos = be32_to_cpu(READ_ONCE(mc->out_pos)); 45 46 /* Now we've read out_pos, put a barrier in before reading the new 47 * data it points to in conbuf. */ 48 smp_rmb(); 49 50 conbuf = phys_to_virt(be64_to_cpu(mc->obuf_phys)); 51 52 /* When the buffer has wrapped, read from the out_pos marker to the end 53 * of the buffer, and then read the remaining data as in the un-wrapped 54 * case. */ 55 if (out_pos & MEMCONS_OUT_POS_WRAP) { 56 57 out_pos &= MEMCONS_OUT_POS_MASK; 58 avail = be32_to_cpu(mc->obuf_size) - out_pos; 59 60 ret = memory_read_from_buffer(to, count, &pos, 61 conbuf + out_pos, avail); 62 63 if (ret < 0) 64 goto out; 65 66 first_read = ret; 67 to += first_read; 68 count -= first_read; 69 pos -= avail; 70 71 if (count <= 0) 72 goto out; 73 } 74 75 /* Sanity check. The firmware should not do this to us. */ 76 if (out_pos > be32_to_cpu(mc->obuf_size)) { 77 pr_err("OPAL: memory console corruption. Aborting read.\n"); 78 return -EINVAL; 79 } 80 81 ret = memory_read_from_buffer(to, count, &pos, conbuf, out_pos); 82 83 if (ret < 0) 84 goto out; 85 86 ret += first_read; 87 out: 88 return ret; 89 } 90 91 ssize_t opal_msglog_copy(char *to, loff_t pos, size_t count) 92 { 93 return memcons_copy(opal_memcons, to, pos, count); 94 } 95 96 static ssize_t opal_msglog_read(struct file *file, struct kobject *kobj, 97 struct bin_attribute *bin_attr, char *to, 98 loff_t pos, size_t count) 99 { 100 return opal_msglog_copy(to, pos, count); 101 } 102 103 static struct bin_attribute opal_msglog_attr = { 104 .attr = {.name = "msglog", .mode = 0400}, 105 .read = opal_msglog_read 106 }; 107 108 struct memcons *__init memcons_init(struct device_node *node, const char *mc_prop_name) 109 { 110 u64 mcaddr; 111 struct memcons *mc; 112 113 if (of_property_read_u64(node, mc_prop_name, &mcaddr)) { 114 pr_warn("%s property not found, no message log\n", 115 mc_prop_name); 116 goto out_err; 117 } 118 119 mc = phys_to_virt(mcaddr); 120 if (!mc) { 121 pr_warn("memory console address is invalid\n"); 122 goto out_err; 123 } 124 125 if (be64_to_cpu(mc->magic) != MEMCONS_MAGIC) { 126 pr_warn("memory console version is invalid\n"); 127 goto out_err; 128 } 129 130 return mc; 131 132 out_err: 133 return NULL; 134 } 135 136 u32 __init memcons_get_size(struct memcons *mc) 137 { 138 return be32_to_cpu(mc->ibuf_size) + be32_to_cpu(mc->obuf_size); 139 } 140 141 void __init opal_msglog_init(void) 142 { 143 opal_memcons = memcons_init(opal_node, "ibm,opal-memcons"); 144 if (!opal_memcons) { 145 pr_warn("OPAL: memcons failed to load from ibm,opal-memcons\n"); 146 return; 147 } 148 149 opal_msglog_attr.size = memcons_get_size(opal_memcons); 150 } 151 152 void __init opal_msglog_sysfs_init(void) 153 { 154 if (!opal_memcons) { 155 pr_warn("OPAL: message log initialisation failed, not creating sysfs entry\n"); 156 return; 157 } 158 159 if (sysfs_create_bin_file(opal_kobj, &opal_msglog_attr) != 0) 160 pr_warn("OPAL: sysfs file creation failed\n"); 161 } 162