Re: [PATCH 2/2] OLPC: Rework BIOS signature check

[Andres Salomon <dilinger@queued.net>]

Definitely an improvement, thanks.  I have some minor style nits to
address, but I can do that w/ a followup patch.

Acked-by: Andres Salomon <dilinger@queued.net>

On Thu, 23 Sep 2010
17:28:46 +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 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>
> ---
> 
> Replaces earlier patch: [PATCH 3/3] OLPC: Extend BIOS signature check
> Now checks OFW's architecture property to be really sure that we're
> running on an OLPC laptop.
> 
>  arch/x86/Kconfig                |    3 +-
>  arch/x86/include/asm/olpc_ofw.h |    4 +++
>  arch/x86/kernel/olpc.c          |   58
> +++++++++++++++++----------------------
> arch/x86/kernel/olpc_ofw.c      |    6 ++++ 4 files changed, 37
> insertions(+), 34 deletions(-)
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 0ed4c9b..c255255 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 08fde47..2a84781 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 635888c..37c49934 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 3218aa7..7873204 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
>