x86, olpc: Add support for calling into OpenFirmware

Add support for saving OFW's cif, and later calling into it to run OFW
commands.  OFW remains resident in memory, living within virtual range
0xff800000 - 0xffc00000.  A single page directory entry points to the
pgdir that OFW actually uses, so rather than saving the entire page
table, we grab and install that one entry permanently in the kernel's
page table.

This is currently only used by the OLPC XO.  Note that this particular
calling convention breaks PAE and PAT, and so cannot be used on newer
x86 hardware.

Signed-off-by: Andres Salomon <dilinger@queued.net>
LKML-Reference: <20100618174653.7755a39a@dev.queued.net>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/arch/x86/include/asm/bootparam.h b/arch/x86/include/asm/bootparam.h
index 6be33d83c716..8e6218550e77 100644
--- a/arch/x86/include/asm/bootparam.h
+++ b/arch/x86/include/asm/bootparam.h
@@ -70,6 +70,14 @@ struct sys_desc_table {
         __u8  table[14];
 };
 
+/* Gleaned from OFW's set-parameters in cpu/x86/pc/linux.fth */
+struct olpc_ofw_header {
+        __u32 ofw_magic;        /* OFW signature */
+        __u32 ofw_version;
+        __u32 cif_handler;      /* callback into OFW */
+        __u32 irq_desc_table;
+} __attribute__((packed));
+
 struct efi_info {
         __u32 efi_loader_signature;
         __u32 efi_systab;
@@ -92,7 +100,8 @@ struct boot_params {
         __u8  hd0_info[16];     /* obsolete! */         /* 0x080 */
         __u8  hd1_info[16];     /* obsolete! */         /* 0x090 */
         struct sys_desc_table sys_desc_table;           /* 0x0a0 */
-        __u8  _pad4[144];                               /* 0x0b0 */
+        struct olpc_ofw_header olpc_ofw_header;         /* 0x0b0 */
+        __u8  _pad4[128];                               /* 0x0c0 */
         struct edid_info edid_info;                     /* 0x140 */
         struct efi_info efi_info;                       /* 0x1c0 */
         __u32 alt_mem_k;                                /* 0x1e0 */