root/arch/powerpc/platforms/powernv/opal-msglog.c

DEFINITIONS

1. memcons_copy
2. opal_msglog_copy
3. opal_msglog_read
4. memcons_init
5. memcons_get_size
6. opal_msglog_init
7. opal_msglog_sysfs_init

   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 }