acpi: Support IBM SMBus CMI devices
Darrick J. Wong [Wed, 24 Mar 2010 13:38:37 +0000 (14:38 +0100)]
On some old IBM workstations and desktop computers, the BIOS presents in the
DSDT an SMBus object that is missing the HID identifier that the i2c-scmi
driver looks for.  Modify the ACPI device scan code to insert the missing HID
if it finds an IBM system with such an object.

Affected machines: IntelliStation Z20/Z30.  Note that the i2c-i801 driver no
longer works on these machines because of ACPI resource conflicts.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

drivers/acpi/scan.c
include/acpi/acpi_drivers.h

index fb7fc24..189cbc2 100644 (file)
@@ -8,6 +8,7 @@
 #include <linux/acpi.h>
 #include <linux/signal.h>
 #include <linux/kthread.h>
+#include <linux/dmi.h>
 
 #include <acpi/acpi_drivers.h>
 
@@ -1032,6 +1033,41 @@ static void acpi_add_id(struct acpi_device *device, const char *dev_id)
        list_add_tail(&id->list, &device->pnp.ids);
 }
 
+/*
+ * Old IBM workstations have a DSDT bug wherein the SMBus object
+ * lacks the SMBUS01 HID and the methods do not have the necessary "_"
+ * prefix.  Work around this.
+ */
+static int acpi_ibm_smbus_match(struct acpi_device *device)
+{
+       acpi_handle h_dummy;
+       struct acpi_buffer path = {ACPI_ALLOCATE_BUFFER, NULL};
+       int result;
+
+       if (!dmi_name_in_vendors("IBM"))
+               return -ENODEV;
+
+       /* Look for SMBS object */
+       result = acpi_get_name(device->handle, ACPI_SINGLE_NAME, &path);
+       if (result)
+               return result;
+
+       if (strcmp("SMBS", path.pointer)) {
+               result = -ENODEV;
+               goto out;
+       }
+
+       /* Does it have the necessary (but misnamed) methods? */
+       result = -ENODEV;
+       if (ACPI_SUCCESS(acpi_get_handle(device->handle, "SBI", &h_dummy)) &&
+           ACPI_SUCCESS(acpi_get_handle(device->handle, "SBR", &h_dummy)) &&
+           ACPI_SUCCESS(acpi_get_handle(device->handle, "SBW", &h_dummy)))
+               result = 0;
+out:
+       kfree(path.pointer);
+       return result;
+}
+
 static void acpi_device_set_id(struct acpi_device *device)
 {
        acpi_status status;
@@ -1082,6 +1118,8 @@ static void acpi_device_set_id(struct acpi_device *device)
                        acpi_add_id(device, ACPI_BAY_HID);
                else if (ACPI_SUCCESS(acpi_dock_match(device)))
                        acpi_add_id(device, ACPI_DOCK_HID);
+               else if (!acpi_ibm_smbus_match(device))
+                       acpi_add_id(device, ACPI_SMBUS_IBM_HID);
 
                break;
        case ACPI_BUS_TYPE_POWER:
index 3a4767c..4f7b448 100644 (file)
@@ -65,6 +65,8 @@
 #define ACPI_VIDEO_HID                 "LNXVIDEO"
 #define ACPI_BAY_HID                   "LNXIOBAY"
 #define ACPI_DOCK_HID                  "LNXDOCK"
+/* Quirk for broken IBM BIOSes */
+#define ACPI_SMBUS_IBM_HID             "SMBUSIBM"
 
 /*
  * For fixed hardware buttons, we fabricate acpi_devices with HID