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