firmware: dmi_scan: add SBMIOS entry and DMI tables

Some utils, like dmidecode and smbios, need to access SMBIOS entry
table area in order to get information like SMBIOS version, size, etc.
Currently it's done via /dev/mem. But for situation when /dev/mem
usage is disabled, the utils have to use dmi sysfs instead, which
doesn't represent SMBIOS entry and adds code/delay redundancy when direct
access for table is needed.

So this patch creates dmi/tables and adds SMBIOS entry point to allow
utils in question to work correctly without /dev/mem. Also patch adds
raw dmi table to simplify dmi table processing in user space, as
proposed by Jean Delvare.

Tested-by: Roy Franz <roy.franz@linaro.org>
Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@globallogic.com>
Signed-off-by: Jean Delvare <jdelvare@suse.de>

1 files changed, 78 insertions, 0 deletions

diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index 7fdf2868a276..5e0b770fdae5 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -10,6 +10,9 @@
 #include <asm/dmi.h>
 #include <asm/unaligned.h>
 
+struct kobject *dmi_kobj;
+EXPORT_SYMBOL_GPL(dmi_kobj);
+
 /*
  * DMI stands for "Desktop Management Interface".  It is part
  * of and an antecedent to, SMBIOS, which stands for System
@@ -20,6 +23,9 @@ static const char dmi_empty_string[] = "        ";
 static u32 dmi_ver __initdata;
 static u32 dmi_len;
 static u16 dmi_num;
+static u8 smbios_entry_point[32];
+static int smbios_entry_point_size;
+
 /*
  * Catch too early calls to dmi_check_system():
  */
@@ -488,6 +494,8 @@ static int __init dmi_present(const u8 *buf)
 	if (memcmp(buf, "_SM_", 4) == 0 &&
 	    buf[5] < 32 && dmi_checksum(buf, buf[5])) {
 		smbios_ver = get_unaligned_be16(buf + 6);
+		smbios_entry_point_size = buf[5];
+		memcpy(smbios_entry_point, buf, smbios_entry_point_size);
 
 		/* Some BIOS report weird SMBIOS version, fix that up */
 		switch (smbios_ver) {
@@ -522,6 +530,9 @@ static int __init dmi_present(const u8 *buf)
 				pr_info("SMBIOS %d.%d present.\n",
 				       dmi_ver >> 8, dmi_ver & 0xFF);
 			} else {
+				smbios_entry_point_size = 15;
+				memcpy(smbios_entry_point, buf,
+				       smbios_entry_point_size);
 				pr_info("Legacy DMI %d.%d present.\n",
 				       dmi_ver >> 8, dmi_ver & 0xFF);
 			}
@@ -548,6 +559,8 @@ static int __init dmi_smbios3_present(const u8 *buf)
 		dmi_num = 0;			/* No longer specified */
 		dmi_len = get_unaligned_le32(buf + 12);
 		dmi_base = get_unaligned_le64(buf + 16);
+		smbios_entry_point_size = buf[6];
+		memcpy(smbios_entry_point, buf, smbios_entry_point_size);
 
 		if (dmi_walk_early(dmi_decode) == 0) {
 			pr_info("SMBIOS %d.%d.%d present.\n",
@@ -639,6 +652,71 @@ void __init dmi_scan_machine(void)
 	dmi_initialized = 1;
 }
 
+static ssize_t raw_table_read(struct file *file, struct kobject *kobj,
+			      struct bin_attribute *attr, char *buf,
+			      loff_t pos, size_t count)
+{
+	memcpy(buf, attr->private + pos, count);
+	return count;
+}
+
+static BIN_ATTR(smbios_entry_point, S_IRUSR, raw_table_read, NULL, 0);
+static BIN_ATTR(DMI, S_IRUSR, raw_table_read, NULL, 0);
+
+static int __init dmi_init(void)
+{
+	struct kobject *tables_kobj;
+	u8 *dmi_table;
+	int ret = -ENOMEM;
+
+	if (!dmi_available) {
+		ret = -ENODATA;
+		goto err;
+	}
+
+	/*
+	 * Set up dmi directory at /sys/firmware/dmi. This entry should stay
+	 * even after farther error, as it can be used by other modules like
+	 * dmi-sysfs.
+	 */
+	dmi_kobj = kobject_create_and_add("dmi", firmware_kobj);
+	if (!dmi_kobj)
+		goto err;
+
+	tables_kobj = kobject_create_and_add("tables", dmi_kobj);
+	if (!tables_kobj)
+		goto err;
+
+	dmi_table = dmi_remap(dmi_base, dmi_len);
+	if (!dmi_table)
+		goto err_tables;
+
+	bin_attr_smbios_entry_point.size = smbios_entry_point_size;
+	bin_attr_smbios_entry_point.private = smbios_entry_point;
+	ret = sysfs_create_bin_file(tables_kobj, &bin_attr_smbios_entry_point);
+	if (ret)
+		goto err_unmap;
+
+	bin_attr_DMI.size = dmi_len;
+	bin_attr_DMI.private = dmi_table;
+	ret = sysfs_create_bin_file(tables_kobj, &bin_attr_DMI);
+	if (!ret)
+		return 0;
+
+	sysfs_remove_bin_file(tables_kobj,
+			      &bin_attr_smbios_entry_point);
+ err_unmap:
+	dmi_unmap(dmi_table);
+ err_tables:
+	kobject_del(tables_kobj);
+	kobject_put(tables_kobj);
+ err:
+	pr_err("dmi: Firmware registration failed.\n");
+
+	return ret;
+}
+subsys_initcall(dmi_init);
+
 /**
  * dmi_set_dump_stack_arch_desc - set arch description for dump_stack()
  *