linux-kernel - Re: [PATCH v14 06/16] of/fdt: add helper functions for handling properties

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Date:   Fri, 7 Sep 2018 12:53:58 -0700
From:   Frank Rowand <frowand.list@...il.com>
To:     AKASHI Takahiro <takahiro.akashi@...aro.org>,
        catalin.marinas@....com, will.deacon@....com, dhowells@...hat.com,
        vgoyal@...hat.com, herbert@...dor.apana.org.au,
        davem@...emloft.net, dyoung@...hat.com, bhe@...hat.com,
        arnd@...db.de, schwidefsky@...ibm.com, heiko.carstens@...ibm.com
Cc:     prudo@...ux.ibm.com, ard.biesheuvel@...aro.org,
        james.morse@....com, bhsharma@...hat.com,
        kexec@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH v14 06/16] of/fdt: add helper functions for handling
 properties

On 09/07/18 01:00, AKASHI Takahiro wrote:
> These functions will be used later to handle kexec-specific properties
> in arm64's kexec_file implementation.
> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
> Cc: Rob Herring <robh+dt@...nel.org>
> Cc: Frank Rowand <frowand.list@...il.com>
> ---
>  drivers/of/fdt.c       | 62 ++++++++++++++++++++++++++++++++++++++++--
>  include/linux/of_fdt.h | 10 +++++--
>  2 files changed, 68 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 800ad252cf9c..dc960cea1355 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -25,6 +25,7 @@
>  #include <linux/debugfs.h>
>  #include <linux/serial_core.h>
>  #include <linux/sysfs.h>
> +#include <linux/types.h>
>  
>  #include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
>  #include <asm/page.h>
> @@ -537,8 +538,8 @@ void *of_fdt_unflatten_tree(const unsigned long *blob,
>  EXPORT_SYMBOL_GPL(of_fdt_unflatten_tree);
>  
>  /* Everything below here references initial_boot_params directly. */
> -int __initdata dt_root_addr_cells;
> -int __initdata dt_root_size_cells;
> +int dt_root_addr_cells;
> +int dt_root_size_cells;
>  
>  void *initial_boot_params;
>  
> @@ -1323,3 +1324,60 @@ late_initcall(of_fdt_raw_init);
>  #endif
>  
>  #endif /* CONFIG_OF_EARLY_FLATTREE */
> +

Please add comment:

/* helper functions for arm64 kexec */


> +bool of_fdt_cells_size_fitted(u64 base, u64 size)

Please rename as of_fdt_range_valid()


> +{
> +	/* if *_cells >= 2, cells can hold 64-bit values anyway */
> +	if ((dt_root_addr_cells == 1) && (base > U32_MAX))
> +		return false;
> +
> +	if ((dt_root_size_cells == 1) && (size > U32_MAX))
> +		return false;

Should also check that base + size does not wrap around.


> +
> +	return true;
> +}
> +
> +size_t of_fdt_reg_cells_size(void)

Please rename as of_fdt_root_range_size()


> +{
> +	return (dt_root_addr_cells + dt_root_size_cells) * sizeof(u32);
> +}
> +
> +#define FDT_ALIGN(x, a)	(((x) + (a) - 1) & ~((a) - 1))
> +#define FDT_TAGALIGN(x)	(FDT_ALIGN((x), FDT_TAGSIZE))
> +
> +int fdt_prop_len(const char *prop_name, int len)

Please rename as fdt_len_added_prop()


> +{
> +	return (strlen(prop_name) + 1) +
> +		sizeof(struct fdt_property) +
> +		FDT_TAGALIGN(len);
> +}
> +

Please add comment, something like:

/* cells must be 1 or 2 */


> +static void fill_property(void *buf, u64 val64, int cells)

Please rename as cpu64_to_fdt_cells()

Thanks,

Frank

> +{
> +	__be32 val32;
> +
> +	while (cells) {
> +		val32 = cpu_to_fdt32((val64 >> (32 * (--cells))) & U32_MAX);
> +		memcpy(buf, &val32, sizeof(val32));
> +		buf += sizeof(val32);
> +	}
> +}
> +
> +int fdt_setprop_reg(void *fdt, int nodeoffset, const char *name,
> +						u64 addr, u64 size)
> +{
> +	char buf[sizeof(__be32) * 2 * 2];
> +		/* assume dt_root_[addr|size]_cells <= 2 */
> +	void *prop;
> +	size_t buf_size;
> +
> +	buf_size = of_fdt_reg_cells_size();
> +	prop = buf;
> +
> +	fill_property(prop, addr, dt_root_addr_cells);
> +	prop += dt_root_addr_cells * sizeof(u32);
> +
> +	fill_property(prop, size, dt_root_size_cells);
> +
> +	return fdt_setprop(fdt, nodeoffset, name, buf, buf_size);
> +}
> diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
> index b9cd9ebdf9b9..9615d6142578 100644
> --- a/include/linux/of_fdt.h
> +++ b/include/linux/of_fdt.h
> @@ -37,8 +37,8 @@ extern void *of_fdt_unflatten_tree(const unsigned long *blob,
>  				   struct device_node **mynodes);
>  
>  /* TBD: Temporary export of fdt globals - remove when code fully merged */
> -extern int __initdata dt_root_addr_cells;
> -extern int __initdata dt_root_size_cells;
> +extern int dt_root_addr_cells;
> +extern int dt_root_size_cells;
>  extern void *initial_boot_params;
>  
>  extern char __dtb_start[];
> @@ -108,5 +108,11 @@ static inline void unflatten_device_tree(void) {}
>  static inline void unflatten_and_copy_device_tree(void) {}
>  #endif /* CONFIG_OF_EARLY_FLATTREE */
>  
> +bool of_fdt_cells_size_fitted(u64 base, u64 size);
> +size_t of_fdt_reg_cells_size(void);
> +int fdt_prop_len(const char *prop_name, int len);
> +int fdt_setprop_reg(void *fdt, int nodeoffset, const char *name,
> +						u64 addr, u64 size);
> +
>  #endif /* __ASSEMBLY__ */
>  #endif /* _LINUX_OF_FDT_H */
>