DMI-based module autoloading

The patch below adds DMI/SMBIOS based module autoloading to the Linux
kernel. The idea is to load laptop drivers automatically (and other
drivers which cannot be autoloaded otherwise), based on the DMI system
identification information of the BIOS.

Right now most distros manually try to load all available laptop
drivers on bootup in the hope that at least one of them loads
successfully. This patch does away with all that, and uses udev to
automatically load matching drivers on the right machines.

Basically the patch just exports the DMI information that has been
parsed by the kernel anyway to userspace via a sysfs device
/sys/class/dmi/id and makes sure that proper modalias attributes are
available. Besides adding the "modalias" attribute it also adds
attributes for a few other DMI fields which might be useful for
writing udev rules.

This patch is not an attempt to export the entire DMI/SMBIOS data to
userspace. We already have "dmidecode" which parses the complete DMI
info from userspace. The purpose of this patch is machine model
identification and good udev integration.

To take advantage of DMI based module autoloading, a driver should
export one or more MODULE_ALIAS fields similar to these:

MODULE_ALIAS("dmi:*:svnMICRO-STARINT'LCO.,LTD:pnMS-1013:pvr0131*:cvnMICRO-STARINT'LCO.,LTD:ct10:*");
MODULE_ALIAS("dmi:*:svnMicro-StarInternational:pnMS-1058:pvr0581:rvnMSI:rnMS-1058:*:ct10:*");
MODULE_ALIAS("dmi:*:svnMicro-StarInternational:pnMS-1412:*:rvnMSI:rnMS-1412:*:cvnMICRO-STARINT'LCO.,LTD:ct10:*");
MODULE_ALIAS("dmi:*:svnNOTEBOOK:pnSAM2000:pvr0131*:cvnMICRO-STARINT'LCO.,LTD:ct10:*");

These lines are specific to my msi-laptop.c driver. They are basically
just a concatenation of a few carefully selected DMI fields with all
potentially bad characters stripped.

Besides laptop drivers, modules like "hdaps", the i2c modules
and the hwmon modules are good candidates for "dmi:" MODULE_ALIAS
lines.

Besides merely exporting the DMI data via sysfs the patch adds
support for a few more DMI fields. Especially the CHASSIS fields are
very useful to identify different laptop modules. The patch also adds
working MODULE_ALIAS lines to my msi-laptop.c driver.

I'd like to thank Kay Sievers for helping me to clean up this patch
for posting it on lkml.

Patch is against Linus' current GIT HEAD. Should probably apply to
older kernels as well without modification.


Signed-off-by: Lennart Poettering <mzxreary@0pointer.de>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 67 insertions, 6 deletions

diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index 37deee6c0c1..f7318b3b51f 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -84,6 +84,7 @@ static int __init dmi_checksum(u8 *buf)
 
 static char *dmi_ident[DMI_STRING_MAX];
 static LIST_HEAD(dmi_devices);
+int dmi_available;
 
 /*
  *      Save a DMI string
@@ -102,6 +103,51 @@ static void __init dmi_save_ident(struct dmi_header *dm, int slot, int string)
         dmi_ident[slot] = p;
 }
 
+static void __init dmi_save_uuid(struct dmi_header *dm, int slot, int index)
+{
+        u8 *d = (u8*) dm + index;
+        char *s;
+        int is_ff = 1, is_00 = 1, i;
+
+        if (dmi_ident[slot])
+                return;
+
+        for (i = 0; i < 16 && (is_ff || is_00); i++) {
+                if(d[i] != 0x00) is_ff = 0;
+                if(d[i] != 0xFF) is_00 = 0;
+        }
+
+        if (is_ff || is_00)
+                return;
+
+        s = dmi_alloc(16*2+4+1);
+        if (!s)
+                return;
+
+        sprintf(s,
+                "%02X%02X%02X%02X-%02X%02X-%02X%02X-%02X%02X-%02X%02X%02X%02X%02X%02X",
+                d[0], d[1], d[2], d[3], d[4], d[5], d[6], d[7],
+                d[8], d[9], d[10], d[11], d[12], d[13], d[14], d[15]);
+
+        dmi_ident[slot] = s;
+}
+
+static void __init dmi_save_type(struct dmi_header *dm, int slot, int index)
+{
+        u8 *d = (u8*) dm + index;
+        char *s;
+
+        if (dmi_ident[slot])
+                return;
+
+        s = dmi_alloc(4);
+        if (!s)
+                return;
+
+        sprintf(s, "%u", *d & 0x7F);
+        dmi_ident[slot] = s;
+}
+
 static void __init dmi_save_devices(struct dmi_header *dm)
 {
         int i, count = (dm->length - sizeof(struct dmi_header)) / 2;
@@ -192,11 +238,21 @@ static void __init dmi_decode(struct dmi_header *dm)
                 dmi_save_ident(dm, DMI_PRODUCT_NAME, 5);
                 dmi_save_ident(dm, DMI_PRODUCT_VERSION, 6);
                 dmi_save_ident(dm, DMI_PRODUCT_SERIAL, 7);
+                dmi_save_uuid(dm, DMI_PRODUCT_UUID, 8);
                 break;
         case 2:         /* Base Board Information */
                 dmi_save_ident(dm, DMI_BOARD_VENDOR, 4);
                 dmi_save_ident(dm, DMI_BOARD_NAME, 5);
                 dmi_save_ident(dm, DMI_BOARD_VERSION, 6);
+                dmi_save_ident(dm, DMI_BOARD_SERIAL, 7);
+                dmi_save_ident(dm, DMI_BOARD_ASSET_TAG, 8);
+                break;
+        case 3:         /* Chassis Information */
+                dmi_save_ident(dm, DMI_CHASSIS_VENDOR, 4);
+                dmi_save_type(dm, DMI_CHASSIS_TYPE, 5);
+                dmi_save_ident(dm, DMI_CHASSIS_VERSION, 6);
+                dmi_save_ident(dm, DMI_CHASSIS_SERIAL, 7);
+                dmi_save_ident(dm, DMI_CHASSIS_ASSET_TAG, 8);
                 break;
         case 10:        /* Onboard Devices Information */
                 dmi_save_devices(dm);
@@ -243,18 +299,20 @@ void __init dmi_scan_machine(void)
                 if (efi.smbios == EFI_INVALID_TABLE_ADDR)
                         goto out;
 
-               /* This is called as a core_initcall() because it isn't
-                * needed during early boot.  This also means we can
-                * iounmap the space when we're done with it.
-                */
+                /* This is called as a core_initcall() because it isn't
+                 * needed during early boot.  This also means we can
+                 * iounmap the space when we're done with it.
+                 */
                 p = dmi_ioremap(efi.smbios, 32);
                 if (p == NULL)
                         goto out;
 
                 rc = dmi_present(p + 0x10); /* offset of _DMI_ string */
                 dmi_iounmap(p, 32);
-                if (!rc)
+                if (!rc) {
+                        dmi_available = 1;
                         return;
+                }
         }
         else {
                 /*
@@ -268,8 +326,10 @@ void __init dmi_scan_machine(void)
 
                 for (q = p; q < p + 0x10000; q += 16) {
                         rc = dmi_present(q);
-                        if (!rc)
+                        if (!rc) {
+                                dmi_available = 1;
                                 return;
+                        }
                 }
         }
  out:   printk(KERN_INFO "DMI not present or invalid.\n");
@@ -404,3 +464,4 @@ int dmi_get_year(int field)
 
         return year;
 }
+