toshiba_acpi: Add /dev/toshiba_acpi device

There were previous attempts to "merge" the toshiba SMM module to the
toshiba_acpi one, they were trying to imitate what the old toshiba
module does, however, some models (TOS1900 devices) come with a
"crippled" implementation and do not provide all the "features" a
"genuine" Toshiba BIOS does.

This patch adds a new device called toshiba_acpi, which aim is to
enable userspace to access the SMM on Toshiba laptops via ACPI calls.

Creating a new convenience _IOWR command to access the SCI functions
by opening/closing the SCI internally to avoid buggy BIOS, while at
the same time providing backwards compatibility.

Older programs (and new) who wish to access the SMM on newer models
can do it by pointing their path to /dev/toshiba_acpi (instead of
/dev/toshiba) as the toshiba.h header was modified to reflect these
changes as well as adds all the toshiba_acpi paths and command,
however, it is strongly recommended to use the new IOCTL for any
SCI command to avoid any buggy BIOS.

Signed-off-by: Azael Avalos <coproscefalo@gmail.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>

1 files changed, 29 insertions, 3 deletions

diff --git a/include/uapi/linux/toshiba.h b/include/uapi/linux/toshiba.h
index e9bef5b2f91e..c58bf4b5bb26 100644
--- a/include/uapi/linux/toshiba.h
+++ b/include/uapi/linux/toshiba.h
@@ -1,6 +1,7 @@
 /* toshiba.h -- Linux driver for accessing the SMM on Toshiba laptops 
  *
  * Copyright (c) 1996-2000  Jonathan A. Buzzard (jonathan@buzzard.org.uk)
+ * Copyright (c) 2015  Azael Avalos <coproscefalo@gmail.com>
  *
  * Thanks to Juergen Heinzl <juergen@monocerus.demon.co.uk> for the pointers
  * on making sure the structure is aligned and packed.
@@ -20,9 +21,18 @@
 #ifndef _UAPI_LINUX_TOSHIBA_H
 #define _UAPI_LINUX_TOSHIBA_H
 
-#define TOSH_PROC "/proc/toshiba"
-#define TOSH_DEVICE "/dev/toshiba"
-#define TOSH_SMM _IOWR('t', 0x90, int)  /* broken: meant 24 bytes */
+/*
+ * Toshiba modules paths
+ */
+
+#define TOSH_PROC               "/proc/toshiba"
+#define TOSH_DEVICE             "/dev/toshiba"
+#define TOSHIBA_ACPI_PROC       "/proc/acpi/toshiba"
+#define TOSHIBA_ACPI_DEVICE     "/dev/toshiba_acpi"
+
+/*
+ * Toshiba SMM structure
+ */
 
 typedef struct {
         unsigned int eax;
@@ -33,5 +43,21 @@ typedef struct {
         unsigned int edi __attribute__ ((packed));
 } SMMRegisters;
 
+/*
+ * IOCTLs (0x90 - 0x91)
+ */
+
+#define TOSH_SMM                _IOWR('t', 0x90, SMMRegisters)
+/*
+ * Convenience toshiba_acpi command.
+ *
+ * The System Configuration Interface (SCI) is opened/closed internally
+ * to avoid userspace of buggy BIOSes.
+ *
+ * The toshiba_acpi module checks whether the eax register is set with
+ * SCI_GET (0xf300) or SCI_SET (0xf400), returning -EINVAL if not.
+ */
+#define TOSHIBA_ACPI_SCI        _IOWR('t', 0x91, SMMRegisters)
+
 
 #endif /* _UAPI_LINUX_TOSHIBA_H */