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SubjectRe: [PATCH] of/fdt: add kernel command line option for dtb_compat string
On 12/06/2010 09:54 AM, dirk.brandewie@gmail.com wrote:
> From: Dirk Brandewie<dirk.brandewie@gmail.com>
>
> Adds a kernel command line option "dtb_compat=<string>". This string
> will be used to select the first compatible device tree blob linked
> into the kernel if a device tree blob is was *not* passed in by the
> bootloader.
>
> Signed-off-by: Dirk Brandewie<dirk.brandewie@gmail.com>
> ---
> Documentation/kernel-parameters.txt | 8 ++++++
> drivers/of/fdt.c | 48 +++++++++++++++++++++++++++++++++++
> 2 files changed, 56 insertions(+), 0 deletions(-)
>
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index 92e83e5..64093e5 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -655,6 +655,14 @@ and is between 256 and 4096 characters. It is defined in the file
>
> dscc4.setup= [NET]
>
> + dtb_compat= [KNL]
> + Specify the "compatible" string for the device
> + tree blob present in the vmlinux image. This
> + string will be used to select the first device
> + tree blob whose compatible property matches
> + the string if a dtb was NOT passed in by the
> + bootloader.
> +
> dynamic_printk Enables pr_debug()/dev_dbg() calls if
> CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
> These can also be switched on/off via
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index c1360e0..ca1318c 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -15,6 +15,8 @@
> #include<linux/of_fdt.h>
> #include<linux/string.h>
> #include<linux/errno.h>
> +#include<asm-generic/vmlinux.lds.h>
> +
>
> #ifdef CONFIG_PPC
> #include<asm/machdep.h>
> @@ -604,3 +606,49 @@ void __init unflatten_device_tree(void)
>
> pr_debug("<- unflatten_device_tree()\n");
> }
> +
> +extern uint8_t __dtb_start[];
> +extern uint8_t __dtb_end[];
> +static void __init *of_flat_dt_find_compatible_dtb(char *name)
> +{
> + void *rc = NULL;
> + unsigned long root, size;
> + struct boot_param_header *orig_initial_boot_params;
> + uint8_t *blob;
> +
> + orig_initial_boot_params = initial_boot_params;
> + blob = __dtb_start;
> + initial_boot_params = (struct boot_param_header *)blob;
> +
> + while (blob< __dtb_end) {
> + if (be32_to_cpu(initial_boot_params->magic) != OF_DT_HEADER) {
> + WARN(1, "Invalid device tree blob in vmlinux\n");
> + break;
> + }
> +
> + root = of_get_flat_dt_root();
> + if (of_flat_dt_is_compatible(root, name)> 0) {
> + rc = blob;
> + break;
> + }
> +
> + size = be32_to_cpu(initial_boot_params->totalsize);
> + blob = PTR_ALIGN(blob + size, STRUCT_ALIGNMENT);
> + initial_boot_params = (struct boot_param_header *)blob;
> + }
> +
> + if (rc == NULL)
> + initial_boot_params = orig_initial_boot_params;
> + return rc;
> +}
> +
> +
> +static int __init of_flat_dtb_compat_setup(char *line)
> +{
> + if (!initial_boot_params)
> + initial_boot_params = of_flat_dt_find_compatible_dtb(line);
> + return 1;
> +}
> +
> +early_param("dtb_compat", of_flat_dtb_compat_setup);
> +
Any more comments on this patch? Is it good to go or DOA?

Thanks
--Dirk



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