[dmidecode] [PATCH 2/2] firmware: dmi-sysfs: add SMBIOS entry point area attribute

[Ivan Khoronzhuk]

There are situations when code needs to access SMBIOS entry table
area, but cannot use /dev/mem for this. As the table format is
consistent only for a version, and can be changed, use binary
attribute to give access to raw SMBIOS entry table area.

Signed-off-by: Ivan Khoronzhuk <address@hidden>
---
 drivers/firmware/dmi-sysfs.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/drivers/firmware/dmi-sysfs.c b/drivers/firmware/dmi-sysfs.c
index e0f1cb3..b5c0558 100644
--- a/drivers/firmware/dmi-sysfs.c
+++ b/drivers/firmware/dmi-sysfs.c
@@ -46,6 +46,8 @@ struct dmi_sysfs_entry {
 static LIST_HEAD(entry_list);
 static DEFINE_SPINLOCK(entry_list_lock);
 
+static unsigned char smbios_raw_header[32];
+
 /* dmi_sysfs_attribute - Top level attribute. used by all entries. */
 struct dmi_sysfs_attribute {
        struct attribute attr;
@@ -646,9 +648,37 @@ static void cleanup_entry_list(void)
        }
 }
 
+static ssize_t smbios_entry_area_raw_read(struct file *filp,
+                                         struct kobject *kobj,
+                                         struct bin_attribute *bin_attr,
+                                         char *buf, loff_t pos, size_t count)
+{
+       ssize_t size;
+
+       size = bin_attr->size;
+
+       if (size > pos)
+               size -= pos;
+       else
+               return 0;
+
+       if (count < size)
+               size = count;
+
+       memcpy(buf, &smbios_raw_header[pos], size);
+
+       return size;
+}
+
+static struct bin_attribute smbios_entry_area_raw_attr = {
+       .read = smbios_entry_area_raw_read,
+       .attr = {.name = "smbios_raw_header", .mode = 0400},
+};
+
 static int __init dmi_sysfs_init(void)
 {
        int error = -ENOMEM;
+       int size;
        int val;
 
        /* Set up our directory */
@@ -669,6 +699,18 @@ static int __init dmi_sysfs_init(void)
                goto err;
        }
 
+       size = dmi_get_smbios_entry_area(smbios_raw_header);
+       if (size == -ENODATA) {
+               pr_debug("dmi-sysfs: SMBIOS raw data is not available.\n");
+               error = size;
+               goto err;
+       }
+
+       /* Create the raw binary file to access the entry area */
+       smbios_entry_area_raw_attr.size = size;
+       if (sysfs_create_bin_file(dmi_kobj, &smbios_entry_area_raw_attr))
+               goto err;
+
        pr_debug("dmi-sysfs: loaded.\n");
 
        return 0;
-- 
1.9.1