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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>
hifive-unleashed-5.1
Andres Salomon 2010-06-18 17:46:53 -04:00 committed by H. Peter Anvin
parent 7e27d6e778
commit fd699c7655
9 changed files with 173 additions and 8 deletions
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1
Documentation/x86/zero-page.txt
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@ -18,6 +18,7 @@ Offset Proto Name Meaning
080/010 ALL hd0_info hd0 disk parameter, OBSOLETE!!
090/010 ALL hd1_info hd1 disk parameter, OBSOLETE!!
0A0/010 ALL sys_desc_table System description table (struct sys_desc_table)
0B0/010 ALL olpc_ofw_header OLPC's OpenFirmware CIF and friends
140/080 ALL edid_info Video mode setup (struct edid_info)
1C0/020 ALL efi_info EFI 32 information (struct efi_info)
1E0/004 ALL alk_mem_k Alternative mem check, in KB

9
arch/x86/Kconfig
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@ -2062,6 +2062,15 @@ config OLPC
Add support for detecting the unique features of the OLPC
XO hardware.
config OLPC_OPENFIRMWARE
bool "Support for OLPC's Open Firmware"
depends on !X86_64 && !X86_PAE
default y if OLPC
help
This option adds support for the implementation of Open Firmware
that is used on the OLPC XO-1 Children's Machine.
If unsure, say N here.
endif # X86_32
config K8_NB

11
arch/x86/include/asm/bootparam.h
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@ -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 */

31
arch/x86/include/asm/olpc_ofw.h 100644
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@ -0,0 +1,31 @@
#ifndef _ASM_X86_OLPC_OFW_H
#define _ASM_X86_OLPC_OFW_H
/* index into the page table containing the entry OFW occupies */
#define OLPC_OFW_PDE_NR 1022
#define OLPC_OFW_SIG 0x2057464F /* aka "OFW " */
#ifdef CONFIG_OLPC_OPENFIRMWARE
/* run an OFW command by calling into the firmware */
#define olpc_ofw(name, args, res) \
__olpc_ofw((name), ARRAY_SIZE(args), args, ARRAY_SIZE(res), res)
extern int __olpc_ofw(const char *name, int nr_args, void **args, int nr_res,
void **res);
/* determine whether OFW is available and lives in the proper memory */
extern void olpc_ofw_detect(void);
/* install OFW's pde permanently into the kernel's pgtable */
extern void setup_olpc_ofw_pgd(void);
#else /* !CONFIG_OLPC_OPENFIRMWARE */
static inline void olpc_ofw_detect(void) { }
static inline void setup_olpc_ofw_pgd(void) { }
#endif /* !CONFIG_OLPC_OPENFIRMWARE */
#endif /* _ASM_X86_OLPC_OFW_H */

1
arch/x86/kernel/Makefile
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@ -104,6 +104,7 @@ obj-$(CONFIG_SCx200) += scx200.o
scx200-y += scx200_32.o
obj-$(CONFIG_OLPC) += olpc.o
obj-$(CONFIG_OLPC_OPENFIRMWARE) += olpc_ofw.o
obj-$(CONFIG_X86_MRST) += mrst.o
microcode-y := microcode_core.o

6
arch/x86/kernel/head_32.S
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@ -131,6 +131,12 @@ ENTRY(startup_32)
movsl
1:
#ifdef CONFIG_OLPC_OPENFIRMWARE
/* save OFW's pgdir table for later use when calling into OFW */
movl %cr3, %eax
movl %eax, pa(olpc_ofw_pgd)
#endif
#ifdef CONFIG_PARAVIRT
/* This is can only trip for a broken bootloader... */
cmpw $0x207, pa(boot_params + BP_version)

12
arch/x86/kernel/olpc.c
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@ -21,10 +21,7 @@
#include <asm/geode.h>
#include <asm/setup.h>
#include <asm/olpc.h>
#ifdef CONFIG_OPEN_FIRMWARE
#include <asm/ofw.h>
#endif
#include <asm/olpc_ofw.h>
struct olpc_platform_t olpc_platform_info;
EXPORT_SYMBOL_GPL(olpc_platform_info);
@ -188,14 +185,15 @@ err:
}
EXPORT_SYMBOL_GPL(olpc_ec_cmd);
#ifdef CONFIG_OPEN_FIRMWARE
#ifdef CONFIG_OLPC_OPENFIRMWARE
static void __init platform_detect(void)
{
size_t propsize;
__be32 rev;
void *args[] = { NULL, "board-revision-int", &rev, (void *)4 };
void *res[] = { &propsize };
if (ofw("getprop", 4, 1, NULL, "board-revision-int", &rev, 4,
&propsize) || propsize != 4) {
if (olpc_ofw("getprop", args, res) || propsize != 4) {
printk(KERN_ERR "ofw: getprop call failed!\n");
rev = cpu_to_be32(0);
}

104
arch/x86/kernel/olpc_ofw.c 100644
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@ -0,0 +1,104 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <asm/page.h>
#include <asm/setup.h>
#include <asm/io.h>
#include <asm/pgtable.h>
#include <asm/olpc_ofw.h>
/* address of OFW callback interface; will be NULL if OFW isn't found */
static int (*olpc_ofw_cif)(int *);
/* page dir entry containing OFW's pgdir table; filled in by head_32.S */
u32 olpc_ofw_pgd __initdata;
static DEFINE_SPINLOCK(ofw_lock);
#define MAXARGS 10
void __init setup_olpc_ofw_pgd(void)
{
pgd_t *base, *ofw_pde;
if (!olpc_ofw_cif)
return;
/* fetch OFW's PDE */
base = early_ioremap(olpc_ofw_pgd, sizeof(olpc_ofw_pgd) * PTRS_PER_PGD);
if (!base) {
printk(KERN_ERR "failed to remap OFW's pgd - disabling OFW!\n");
olpc_ofw_cif = NULL;
return;
}
ofw_pde = &base[OLPC_OFW_PDE_NR];
/* install OFW's PDE permanently into the kernel's pgtable */
set_pgd(&swapper_pg_dir[OLPC_OFW_PDE_NR], *ofw_pde);
early_iounmap(base, sizeof(olpc_ofw_pgd) * PTRS_PER_PGD);
}
int __olpc_ofw(const char *name, int nr_args, void **args, int nr_res,
void **res)
{
int ofw_args[MAXARGS + 3];
unsigned long flags;
int ret, i, *p;
BUG_ON(nr_args + nr_res > MAXARGS);
if (!olpc_ofw_cif)
return -EIO;
ofw_args[0] = (int)name;
ofw_args[1] = nr_args;
ofw_args[2] = nr_res;
p = &ofw_args[3];
for (i = 0; i < nr_args; i++, p++)
*p = (int)args[i];
/* call into ofw */
spin_lock_irqsave(&ofw_lock, flags);
ret = olpc_ofw_cif(ofw_args);
spin_unlock_irqrestore(&ofw_lock, flags);
if (!ret) {
for (i = 0; i < nr_res; i++, p++)
*((int *)res[i]) = *p;
}
return ret;
}
EXPORT_SYMBOL_GPL(__olpc_ofw);
/* OFW cif _should_ be above this address */
#define OFW_MIN 0xff000000
/* OFW starts on a 1MB boundary */
#define OFW_BOUND (1<<20)
void __init olpc_ofw_detect(void)
{
struct olpc_ofw_header *hdr = &boot_params.olpc_ofw_header;
unsigned long start;
/* ensure OFW booted us by checking for "OFW " string */
if (hdr->ofw_magic != OLPC_OFW_SIG)
return;
olpc_ofw_cif = (int (*)(int *))hdr->cif_handler;
if ((unsigned long)olpc_ofw_cif < OFW_MIN) {
printk(KERN_ERR "OFW detected, but cif has invalid address 0x%lx - disabling.\n",
(unsigned long)olpc_ofw_cif);
olpc_ofw_cif = NULL;
return;
}
/* determine where OFW starts in memory */
start = round_down((unsigned long)olpc_ofw_cif, OFW_BOUND);
printk(KERN_INFO "OFW detected in memory, cif @ 0x%lx (reserving top %ldMB)\n",
(unsigned long)olpc_ofw_cif, (-start) >> 20);
reserve_top_address(-start);
}

6
arch/x86/kernel/setup.c
View File

@ -102,6 +102,7 @@
#include <asm/paravirt.h>
#include <asm/hypervisor.h>
#include <asm/olpc_ofw.h>
#include <asm/percpu.h>
#include <asm/topology.h>
@ -736,10 +737,15 @@ void __init setup_arch(char **cmdline_p)
/* VMI may relocate the fixmap; do this before touching ioremap area */
vmi_init();
/* OFW also may relocate the fixmap */
olpc_ofw_detect();
early_trap_init();
early_cpu_init();
early_ioremap_init();
setup_olpc_ofw_pgd();
ROOT_DEV = old_decode_dev(boot_params.hdr.root_dev);
screen_info = boot_params.screen_info;
edid_info = boot_params.edid_info;