x86, olpc: Rework BIOS signature check

The XO-1.5 laptop is not currently detected as an OLPC machine because
it fails this XO-1-centric check.

Now that we have OLPC OFW support in the kernel, a more sensible
check is to see if we found OFW during boot and check the architecture
property.

Also remove a now-meaningless codepath, as we're always going to have
OFW support with OLPC.

Signed-off-by: Daniel Drake <dsd@laptop.org>
LKML-Reference: <20100923162846.D8D409D401B@zog.reactivated.net>
Cc: Andres Salomon <dilinger@queued.net>
Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

4 files changed, 37 insertions, 34 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 0ed4c9bfcd13..c25525571347 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2061,6 +2061,7 @@ config SCx200HR_TIMER
 config OLPC
         bool "One Laptop Per Child support"
         select GPIOLIB
+        select OLPC_OPENFIRMWARE
         ---help---
           Add support for detecting the unique features of the OLPC
           XO hardware.
@@ -2068,7 +2069,7 @@ config OLPC
 config OLPC_OPENFIRMWARE
         bool "Support for OLPC's Open Firmware"
         depends on !X86_64 && !X86_PAE
-        default y if OLPC
+        default n
         help
           This option adds support for the implementation of Open Firmware
           that is used on the OLPC XO-1 Children's Machine.
diff --git a/arch/x86/include/asm/olpc_ofw.h b/arch/x86/include/asm/olpc_ofw.h
index 08fde475cb3b..2a8478140bb3 100644
--- a/arch/x86/include/asm/olpc_ofw.h
+++ b/arch/x86/include/asm/olpc_ofw.h
@@ -21,10 +21,14 @@ extern void olpc_ofw_detect(void);
 /* install OFW's pde permanently into the kernel's pgtable */
 extern void setup_olpc_ofw_pgd(void);
 
+/* check if OFW was detected during boot */
+extern bool olpc_ofw_present(void);
+
 #else /* !CONFIG_OLPC_OPENFIRMWARE */
 
 static inline void olpc_ofw_detect(void) { }
 static inline void setup_olpc_ofw_pgd(void) { }
+static inline bool olpc_ofw_present(void) { return false; }
 
 #endif /* !CONFIG_OLPC_OPENFIRMWARE */
 
diff --git a/arch/x86/kernel/olpc.c b/arch/x86/kernel/olpc.c
index 635888cf050d..37c49934c785 100644
--- a/arch/x86/kernel/olpc.c
+++ b/arch/x86/kernel/olpc.c
@@ -183,8 +183,21 @@ err:
 }
 EXPORT_SYMBOL_GPL(olpc_ec_cmd);
 
-#ifdef CONFIG_OLPC_OPENFIRMWARE
-static void __init platform_detect(void)
+static bool __init check_ofw_architecture(void)
+{
+        size_t propsize;
+        char olpc_arch[5];
+        const void *args[] = { NULL, "architecture", olpc_arch, (void *)5 };
+        void *res[] = { &propsize };
+
+        if (olpc_ofw("getprop", args, res)) {
+                printk(KERN_ERR "ofw: getprop call failed!\n");
+                return false;
+        }
+        return propsize == 5 && strncmp("OLPC", olpc_arch, 5) == 0;
+}
+
+static u32 __init get_board_revision(void)
 {
         size_t propsize;
         __be32 rev;
@@ -193,46 +206,27 @@ static void __init platform_detect(void)
 
         if (olpc_ofw("getprop", args, res) || propsize != 4) {
                 printk(KERN_ERR "ofw: getprop call failed!\n");
-                rev = cpu_to_be32(0);
+                return cpu_to_be32(0);
         }
-        olpc_platform_info.boardrev = be32_to_cpu(rev);
+        return be32_to_cpu(rev);
 }
-#else
-static void __init platform_detect(void)
+
+static bool __init platform_detect(void)
 {
-        /* stopgap until OFW support is added to the kernel */
-        olpc_platform_info.boardrev = olpc_board(0xc2);
+        if (!check_ofw_architecture())
+                return false;
+        olpc_platform_info.flags |= OLPC_F_PRESENT;
+        olpc_platform_info.boardrev = get_board_revision();
+        return true;
 }
-#endif
 
 static int __init olpc_init(void)
 {
-        unsigned char *romsig;
-
-        /* The ioremap check is dangerous; limit what we run it on */
-        if (!is_geode() || cs5535_has_vsa2())
+        if (!olpc_ofw_present() || !platform_detect())
                 return 0;
 
         spin_lock_init(&ec_lock);
 
-        romsig = ioremap(0xffffffc0, 16);
-        if (!romsig)
-                return 0;
-
-        if (strncmp(romsig, "CL1   Q", 7))
-                goto unmap;
-        if (strncmp(romsig+6, romsig+13, 3)) {
-                printk(KERN_INFO "OLPC BIOS signature looks invalid.  "
-                                "Assuming not OLPC\n");
-                goto unmap;
-        }
-
-        printk(KERN_INFO "OLPC board with OpenFirmware %.16s\n", romsig);
-        olpc_platform_info.flags |= OLPC_F_PRESENT;
-
-        /* get the platform revision */
-        platform_detect();
-
         /* assume B1 and above models always have a DCON */
         if (olpc_board_at_least(olpc_board(0xb1)))
                 olpc_platform_info.flags |= OLPC_F_DCON;
@@ -254,8 +248,6 @@ static int __init olpc_init(void)
                         olpc_platform_info.boardrev >> 4,
                         olpc_platform_info.ecver);
 
-unmap:
-        iounmap(romsig);
         return 0;
 }
 
diff --git a/arch/x86/kernel/olpc_ofw.c b/arch/x86/kernel/olpc_ofw.c
index 3218aa71ab5e..787320464379 100644
--- a/arch/x86/kernel/olpc_ofw.c
+++ b/arch/x86/kernel/olpc_ofw.c
@@ -74,6 +74,12 @@ int __olpc_ofw(const char *name, int nr_args, const void **args, int nr_res,
 }
 EXPORT_SYMBOL_GPL(__olpc_ofw);
 
+bool olpc_ofw_present(void)
+{
+        return olpc_ofw_cif != NULL;
+}
+EXPORT_SYMBOL_GPL(olpc_ofw_present);
+
 /* OFW cif _should_ be above this address */
 #define OFW_MIN 0xff000000