[PATCH] of: Support CONFIG_CMDLINE_EXTEND config option

[Rob Herring]

On 01/09/2012 06:54 PM, Doug Anderson wrote:
> The old logic assumes CMDLINE_FROM_BOOTLOADER vs. CMDLINE_FORCE and
> ignores CMDLINE_EXTEND.  Here's the old logic:
> 
> - CONFIG_CMDLINE_FORCE=true
>     CONFIG_CMDLINE
> - dt bootargs=non-empty:
>     dt bootargs
> - dt bootargs=empty, @data is non-empty string
>     @data is left unchanged
> - dt bootargs=empty, @data is empty string
>     CONFIG_CMDLINE (or "" if that's not defined)
> 
> The old logic would also not honor CONFIG_CMDLINE_FORCE if there was no
> "chosen" attribute in the device tree.
> 
> The new logic is now documented in of_fdt.h and is copied here for
> reference:
> 
> - CONFIG_CMDLINE_FORCE=true
>     CONFIG_CMDLINE
> - CONFIG_CMDLINE_EXTEND=true
>     CONFIG_CMDLINE + dt bootargs (even if dt bootargs are empty)
> - CMDLINE_FROM_BOOTLOADER=true, dt bootargs=non-empty:
>     dt bootargs
> - CMDLINE_FROM_BOOTLOADER=true, dt bootargs=empty, @data is non-empty string
>     @data is left unchanged
> - CMDLINE_FROM_BOOTLOADER=true, dt bootargs=empty, @data is empty string
>     CONFIG_CMDLINE (or "" if that's not defined)
> 
> Signed-off-by: Doug Anderson <dianders at chromium.org>
> CC: devicetree-discuss at lists-ozlabs.org
> CC: Grant Likely <grant.likely at secretlab.ca>
> CC: Benjamin Herrenschmidt <benh at kernel.crashing.org>
> ---

Acked-by: Rob Herring <rob.herring at calxeda.com>

I'll apply, but would like Ben's ack first.

Rob

>  drivers/of/fdt.c       |   56 ++++++++++++++++++++++++++++++++++-------------
>  include/linux/of_fdt.h |   19 ++++++++++++++++
>  2 files changed, 59 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index ea2bd1b..577f3a9 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -664,6 +664,29 @@ int __init early_init_dt_scan_memory(unsigned long node, const char *uname,
>  	return 0;
>  }
>  
> +/*
> + * Convert configs to something easy to use in C code
> + */
> +#if defined(CONFIG_CMDLINE_FORCE)
> +static const int overwrite_incoming_cmdline = 1;
> +static const int read_dt_cmdline;
> +static const int concat_cmdline;
> +#elif defined(CONFIG_CMDLINE_EXTEND)
> +static const int overwrite_incoming_cmdline = 1;
> +static const int read_dt_cmdline = 1;
> +static const int concat_cmdline = 1;
> +#else /* CMDLINE_FROM_BOOTLOADER */
> +static const int overwrite_incoming_cmdline;
> +static const int read_dt_cmdline = 1;
> +static const int concat_cmdline;
> +#endif
> +
> +#ifdef CONFIG_CMDLINE
> +static const char *config_cmdline = CONFIG_CMDLINE;
> +#else
> +static const char *config_cmdline = "";
> +#endif
> +
>  int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
>  				     int depth, void *data)
>  {
> @@ -672,28 +695,29 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
>  
>  	pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname);
>  
> +	/* Make sure cmdline default is set early to handle case of no chosen */
> +	if (data && (overwrite_incoming_cmdline || !((char *)data)[0]))
> +		strlcpy(data, config_cmdline, COMMAND_LINE_SIZE);
> +
>  	if (depth != 1 || !data ||
>  	    (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen at 0") != 0))
>  		return 0;
>  
>  	early_init_dt_check_for_initrd(node);
>  
> -	/* Retrieve command line */
> -	p = of_get_flat_dt_prop(node, "bootargs", &l);
> -	if (p != NULL && l > 0)
> -		strlcpy(data, p, min((int)l, COMMAND_LINE_SIZE));
> -
> -	/*
> -	 * CONFIG_CMDLINE is meant to be a default in case nothing else
> -	 * managed to set the command line, unless CONFIG_CMDLINE_FORCE
> -	 * is set in which case we override whatever was found earlier.
> -	 */
> -#ifdef CONFIG_CMDLINE
> -#ifndef CONFIG_CMDLINE_FORCE
> -	if (!((char *)data)[0])
> -#endif
> -		strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
> -#endif /* CONFIG_CMDLINE */
> +	/* Retrieve command line unless forcing */
> +	if (read_dt_cmdline) {
> +		p = of_get_flat_dt_prop(node, "bootargs", &l);
> +		if (p != NULL && l > 0) {
> +			if (concat_cmdline) {
> +				strlcat(data, " ", COMMAND_LINE_SIZE);
> +				strlcat(data, p, min_t(int, (int)l,
> +						       COMMAND_LINE_SIZE));
> +			} else
> +				strlcpy(data, p, min_t(int, (int)l,
> +						       COMMAND_LINE_SIZE));
> +		}
> +	}
>  
>  	pr_debug("Command line is: %s\n", (char*)data);
>  
> diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
> index ed136ad..346d6c7 100644
> --- a/include/linux/of_fdt.h
> +++ b/include/linux/of_fdt.h
> @@ -91,6 +91,25 @@ extern int of_flat_dt_is_compatible(unsigned long node, const char *name);
>  extern int of_flat_dt_match(unsigned long node, const char *const *matches);
>  extern unsigned long of_get_flat_dt_root(void);
>  
> +/*
> + * early_init_dt_scan_chosen - scan the device tree for ramdisk and bootargs
> + *
> + * The boot arguments will be placed into the memory pointed to by @data.
> + * That memory should be COMMAND_LINE_SIZE big and initialized to be a valid
> + * (possibly empty) string.  Logic for what will be in @data after this
> + * function finishes:
> + *
> + * - CONFIG_CMDLINE_FORCE=true
> + *     CONFIG_CMDLINE
> + * - CONFIG_CMDLINE_EXTEND=true
> + *     CONFIG_CMDLINE + dt bootargs (even if dt bootargs are empty)
> + * - CMDLINE_FROM_BOOTLOADER=true, dt bootargs=non-empty:
> + *     dt bootargs
> + * - CMDLINE_FROM_BOOTLOADER=true, dt bootargs=empty, @data is non-empty string
> + *     @data is left unchanged
> + * - CMDLINE_FROM_BOOTLOADER=true, dt bootargs=empty, @data is empty string
> + *     CONFIG_CMDLINE (or "" if that's not defined)
> + */
>  extern int early_init_dt_scan_chosen(unsigned long node, const char *uname,
>  				     int depth, void *data);
>  extern void early_init_dt_check_for_initrd(unsigned long node);