From: Dirk Brandewie <dirk.brandewie@xxxxxxxxx> 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@xxxxxxxxx> --- 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); + -- 1.7.2.3 -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html