Re: [RFC v2] OLPC: add missing elements to device tree

[Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>]

On Sat, Mar 12, 2011 at 06:04:48PM +0000, Daniel Drake wrote:
> In response to new device tree code in the kernel, OLPC will start
> using it for probing of certain devices. However, some firmware fixes
> are needed to put the devicetree into a usable state.
> 
> Retain compatibility with old firmware by fixing up the device tree
> at boot-time if it does not contain the new nodes/properties that
> we need for probing.
> 
> Signed-off-by: Daniel Drake <dsd-2X9k7bc8m7Mdnm+yROfE0A@public.gmane.org>

Looks okay to me.

Acked-by: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>

g.

> ---
>  arch/x86/platform/olpc/olpc_dt.c |  104 ++++++++++++++++++++++++++++++++++++++
>  1 files changed, 104 insertions(+), 0 deletions(-)
> 
> v2: ask OpenFirmware to adjust the tree instead of manipulating the tree
> on the linux level.
> 
> diff --git a/arch/x86/platform/olpc/olpc_dt.c b/arch/x86/platform/olpc/olpc_dt.c
> index 24f2598..d6ee929 100644
> --- a/arch/x86/platform/olpc/olpc_dt.c
> +++ b/arch/x86/platform/olpc/olpc_dt.c
> @@ -21,6 +21,7 @@
>  #include <linux/of.h>
>  #include <linux/of_platform.h>
>  #include <linux/of_pdt.h>
> +#include <asm/olpc.h>
>  #include <asm/olpc_ofw.h>
>  
>  static phandle __init olpc_dt_getsibling(phandle node)
> @@ -164,6 +165,107 @@ static struct of_pdt_ops prom_olpc_ops __initdata = {
>  	.pkg2path = olpc_dt_pkg2path,
>  };
>  
> +static phandle __init olpc_dt_finddevice(const char *path)
> +{
> +	phandle node;
> +	const void *args[] = { path };
> +	void *res[] = { &node };
> +
> +	if (olpc_ofw("finddevice", args, res)) {
> +		pr_err("olpc_dt: finddevice failed!\n");
> +		return 0;
> +	}
> +
> +	if ((s32) node == -1)
> +		return 0;
> +
> +	return node;
> +}
> +
> +static int __init olpc_dt_interpret(const char *words)
> +{
> +	int result;
> +	const void *args[] = { words };
> +	void *res[] = { &result };
> +
> +	if (olpc_ofw("interpret", args, res)) {
> +		pr_err("olpc_dt: interpret failed!\n");
> +		return -1;
> +	}
> +
> +	return result;
> +}
> +
> +/*
> + * Extract board revision directly from OFW device tree.
> + * We can't use olpc_platform_info because that hasn't been set up yet.
> + */
> +static u32 __init olpc_dt_get_board_revision(void)
> +{
> +	phandle node;
> +	__be32 rev;
> +	int r;
> +
> +	node = olpc_dt_finddevice("/");
> +	if (!node)
> +		return 0;
> +
> +	r = olpc_dt_getproperty(node, "board-revision-int",
> +				(char *) &rev, sizeof(rev));
> +	if (r < 0)
> +		return 0;
> +
> +	return be32_to_cpu(rev);
> +}
> +
> +void __init olpc_dt_fixup(void)
> +{
> +	int r;
> +	char buf[64];
> +	phandle node;
> +	u32 board_rev;
> +
> +	node = olpc_dt_finddevice("/battery@0");
> +	if (!node)
> +		return;
> +
> +	/*
> +	 * If the battery node has a compatible property, we are running a new
> +	 * enough firmware and don't have fixups to make.
> +	 */
> +	r = olpc_dt_getproperty(node, "compatible", buf, sizeof(buf));
> +	if (r > 0)
> +		return;
> +
> +	pr_info("PROM DT: Old firmware detected, applying fixes\n");
> +
> +	/* Add olpc,xo1-battery compatible marker to battery node */
> +	olpc_dt_interpret("\" /battery@0\" find-device"
> +		" \" olpc,xo1-battery\" +compatible"
> +		" device-end");
> +
> +	board_rev = olpc_dt_get_board_revision();
> +	if (!board_rev)
> +		return;
> +
> +	if (board_rev >= olpc_board_pre(0xd0)) {
> +		/* XO-1.5: add dcon device */
> +		olpc_dt_interpret("\" /pci/display@1\" find-device"
> +			" new-device"
> +			" \" dcon\" device-name \" olpc,xo1-dcon\" +compatible"
> +			" finish-device device-end");
> +	} else {
> +		/* XO-1: add dcon device, mark RTC as olpc,xo1-rtc */
> +		olpc_dt_interpret("\" /pci/display@1,1\" find-device"
> +			" new-device"
> +			" \" dcon\" device-name \" olpc,xo1-dcon\" +compatible"
> +			" finish-device device-end"
> +			" \" /rtc\" find-device"
> +			" \" olpc,xo1-rtc\" +compatible"
> +			" device-end");
> +	}
> +}
> +
>  void __init olpc_dt_build_devicetree(void)
>  {
>  	phandle root;
> @@ -171,6 +273,8 @@ void __init olpc_dt_build_devicetree(void)
>  	if (!olpc_ofw_is_installed())
>  		return;
>  
> +	olpc_dt_fixup();
> +
>  	root = olpc_dt_getsibling(0);
>  	if (!root) {
>  		pr_err("PROM: unable to get root node from OFW!\n");
> -- 
> 1.7.4
>