[PATCH 3/3] OLPC: Extend BIOS signature check

[PATCH 3/3] OLPC: Extend BIOS signature check

[Daniel Drake]

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. This also eliminates the need to check
the BIOS signature, since we trust the detection code in olpc_ofw.c

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>
---
 arch/x86/Kconfig                |    2 +-
 arch/x86/include/asm/olpc_ofw.h |    4 ++++
 arch/x86/kernel/olpc.c          |   28 +---------------------------
 arch/x86/kernel/olpc_ofw.c      |    6 ++++++
 4 files changed, 12 insertions(+), 28 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 708ee0d..405237a 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2055,6 +2055,7 @@ config OLPC
 	select PCI
 	select PCI_GOANY
 	select GPIOLIB
+	select OLPC_OPENFIRMWARE
 	---help---
 	  Add support for detecting the unique features of the OLPC
 	  XO hardware.
@@ -2062,7 +2063,6 @@ config OLPC
 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.
diff --git a/arch/x86/include/asm/olpc_ofw.h b/arch/x86/include/asm/olpc_ofw.h
index 08fde47..3db5556 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 */
+int 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 int olpc_ofw_present(void) { return 0; }
 
 #endif /* !CONFIG_OLPC_OPENFIRMWARE */
 
diff --git a/arch/x86/kernel/olpc.c b/arch/x86/kernel/olpc.c
index 10b4dce..52ecc3f 100644
--- a/arch/x86/kernel/olpc.c
+++ b/arch/x86/kernel/olpc.c
@@ -183,7 +183,6 @@ err:
 }
 EXPORT_SYMBOL_GPL(olpc_ec_cmd);
 
-#ifdef CONFIG_OLPC_OPENFIRMWARE
 static void __init platform_detect(void)
 {
 	size_t propsize;
@@ -197,37 +196,14 @@ static void __init platform_detect(void)
 	}
 	olpc_platform_info.boardrev = be32_to_cpu(rev);
 }
-#else
-static void __init platform_detect(void)
-{
-	/* stopgap until OFW support is added to the kernel */
-	olpc_platform_info.boardrev = olpc_board(0xc2);
-}
-#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())
 		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 */
@@ -250,8 +226,6 @@ 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 3218aa7..e7bfcc4 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);
 
+int 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
 
-- 
1.7.2.2

Re: [PATCH 3/3] OLPC: Extend BIOS signature check

[Andres Salomon]

On Wed, 22 Sep 2010 17:44:37 +0100 (BST)
Daniel Drake <dsd@laptop.org> wrote:

> 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. This also eliminates the
> need to check the BIOS signature, since we trust the detection code
> in olpc_ofw.c
> 
> 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>
[...]
> diff --git a/arch/x86/kernel/olpc.c b/arch/x86/kernel/olpc.c
> index 10b4dce..52ecc3f 100644
> --- a/arch/x86/kernel/olpc.c
> +++ b/arch/x86/kernel/olpc.c
> @@ -183,7 +183,6 @@ err:
>  }
>  EXPORT_SYMBOL_GPL(olpc_ec_cmd);
>  
> -#ifdef CONFIG_OLPC_OPENFIRMWARE
>  static void __init platform_detect(void)
>  {
>  	size_t propsize;
> @@ -197,37 +196,14 @@ static void __init platform_detect(void)
>  	}
>  	olpc_platform_info.boardrev = be32_to_cpu(rev);
>  }
> -#else
> -static void __init platform_detect(void)
> -{
> -	/* stopgap until OFW support is added to the kernel */
> -	olpc_platform_info.boardrev = olpc_board(0xc2);
> -}
> -#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())
>  		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); 
>  
>  	/* get the platform revision */
> @@ -250,8 +226,6 @@ static int __init olpc_init(void)
>  			olpc_platform_info.boardrev >> 4,
>  			olpc_platform_info.ecver);
>  
> -unmap:
> -	iounmap(romsig);
>  	return 0;
>  }
>  

I'm ecstatic to see this stuff go away.  However, Mitch has pointed out
that there are embedded x86 machines running OFW, so just checking for
the existence of OFW is not enough.

My suggestion would be to change to code to something like:


spin_lock_init(&ec_lock);
if (!olpc_ofw_present() && !olpc_platform_detect())
	return 0;  
olpc_platform_info.flags |= OLPC_F_PRESENT;


static int __init olpc_platform_detect(void)
{
	const char *olpc_arch = NULL;
	void *res[] = { &olpc_arch };

	/* fetch "architecture" property from / of devtree here */
 
	if (!olpc_arch || strncmp(olpc_arch, "olpc"))
		return -ENODEV;

	return platform_detect();
}

And actually, once the device-tree stuff is upstream (still pending
reviews), you can probably fetch the architecture from that rather than
calling into OFW.

> diff --git a/arch/x86/kernel/olpc_ofw.c b/arch/x86/kernel/olpc_ofw.c
> index 3218aa7..e7bfcc4 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);
>  
> +int olpc_ofw_present(void)
> +{
> +	return olpc_ofw_cif != NULL;
> +}
> +EXPORT_SYMBOL_GPL(olpc_ofw_present);

Definitely should return a bool.

> +
>  /* OFW cif _should_ be above this address */
>  #define OFW_MIN 0xff000000
>