[PATCH v8 7/8] blkmap: add an attribute to preserve the mem mapping

[Heinrich Schuchardt]

On 12.03.25 09:54, Sughosh Ganu wrote:
> Some blkmap memory mapped devices might have to be relevant even after
> U-Boot passes control to the next image as part of the platform
> boot. An example of such a mapping would be an OS installer ISO image,
> information for which has to be provided to the OS kernel. Use the
> 'preserve' attribute for such mappings. The code for adding a pmem
> node to the device-tree then checks if this attribute is set, and adds
> a node only for mappings which have this attribute.
> 
> Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
> Reviewed-by: Tobias Waldekranz <tobias at waldekranz.com>
> Reviewed-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> ---
> Changes since V7:
> * Fix repeated word in the commit message
> 
>   cmd/blkmap.c                  |  9 +++++++--
>   drivers/block/blkmap.c        | 12 ++++++++----
>   drivers/block/blkmap_helper.c |  2 +-
>   include/blkmap.h              |  4 +++-
>   4 files changed, 19 insertions(+), 8 deletions(-)
> 
> diff --git a/cmd/blkmap.c b/cmd/blkmap.c
> index 164f80f1387..86a123b1cd3 100644
> --- a/cmd/blkmap.c
> +++ b/cmd/blkmap.c
> @@ -62,13 +62,18 @@ static int do_blkmap_map_mem(struct map_ctx *ctx, int argc, char *const argv[])
>   {
>   	phys_addr_t addr;
>   	int err;
> +	bool preserve = false;
>   
>   	if (argc < 2)
>   		return CMD_RET_USAGE;
>   
>   	addr = hextoul(argv[1], NULL);
>   
> -	err = blkmap_map_pmem(ctx->dev, ctx->blknr, ctx->blkcnt, addr);
> +	if (argc == 3 && !strcmp(argv[2], "preserve"))
> +		preserve = true;
> +
> +	err = blkmap_map_pmem(ctx->dev, ctx->blknr, ctx->blkcnt, addr,
> +			      preserve);
>   	if (err) {
>   		printf("Unable to map %#llx at block 0x" LBAF ": %d\n",
>   		       (unsigned long long)addr, ctx->blknr, err);
> @@ -221,7 +226,7 @@ U_BOOT_CMD_WITH_SUBCMDS(
>   	"blkmap create <label> - create device\n"
>   	"blkmap destroy <label> - destroy device\n"
>   	"blkmap map <label> <blk#> <cnt> linear <interface> <dev> <blk#> - device mapping\n"
> -	"blkmap map <label> <blk#> <cnt> mem <addr> - memory mapping\n",
> +	"blkmap map <label> <blk#> <cnt> mem <addr> [preserve] - memory mapping\n",
>   	U_BOOT_SUBCMD_MKENT(info, 2, 1, do_blkmap_common),
>   	U_BOOT_SUBCMD_MKENT(part, 2, 1, do_blkmap_common),
>   	U_BOOT_SUBCMD_MKENT(dev, 4, 1, do_blkmap_common),
> diff --git a/drivers/block/blkmap.c b/drivers/block/blkmap.c
> index 453510cca62..eefed615998 100644
> --- a/drivers/block/blkmap.c
> +++ b/drivers/block/blkmap.c
> @@ -19,6 +19,7 @@ struct blkmap;
>   /* Attributes of blkmap slice */
>   #define BLKMAP_SLICE_LINEAR	BIT(0)
>   #define BLKMAP_SLICE_MEM	BIT(1)

Documentation is missing here.

Cf. 
https://docs.kernel.org/doc-guide/kernel-doc.html#object-like-macro-documentation

> +#define BLKMAP_SLICE_PRESERVE	BIT(2)
>   
>   /**
>    * struct blkmap_slice - Region mapped to a blkmap
> @@ -241,7 +242,7 @@ static void blkmap_mem_destroy(struct blkmap *bm, struct blkmap_slice *bms)
>   }
>   
>   int __blkmap_map_mem(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
> -		     void *addr, bool remapped)
> +		     void *addr, bool remapped, bool preserve)
>   {
>   	struct blkmap *bm = dev_get_plat(dev);
>   	struct blkmap_mem *bmm;
> @@ -266,6 +267,9 @@ int __blkmap_map_mem(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
>   		.remapped = remapped,
>   	};
>   
> +	if (preserve)
> +		bmm->slice.attr |= BLKMAP_SLICE_PRESERVE;
> +
>   	err = blkmap_slice_add(bm, &bmm->slice);
>   	if (err)
>   		free(bmm);
> @@ -276,11 +280,11 @@ int __blkmap_map_mem(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
>   int blkmap_map_mem(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
>   		   void *addr)
>   {
> -	return __blkmap_map_mem(dev, blknr, blkcnt, addr, false);
> +	return __blkmap_map_mem(dev, blknr, blkcnt, addr, false, false);
>   }
>   
>   int blkmap_map_pmem(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
> -		    phys_addr_t paddr)
> +		    phys_addr_t paddr, bool preserve)
>   {
>   	struct blkmap *bm = dev_get_plat(dev);
>   	struct blk_desc *bd = dev_get_uclass_plat(bm->blk);
> @@ -291,7 +295,7 @@ int blkmap_map_pmem(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
>   	if (!addr)
>   		return -ENOMEM;
>   
> -	err = __blkmap_map_mem(dev, blknr, blkcnt, addr, true);
> +	err = __blkmap_map_mem(dev, blknr, blkcnt, addr, true, preserve);
>   	if (err)
>   		unmap_sysmem(addr);
>   
> diff --git a/drivers/block/blkmap_helper.c b/drivers/block/blkmap_helper.c
> index bfba14110d2..2f1bc28ee5d 100644
> --- a/drivers/block/blkmap_helper.c
> +++ b/drivers/block/blkmap_helper.c
> @@ -28,7 +28,7 @@ int blkmap_create_ramdisk(const char *label, ulong image_addr, ulong image_size,
>   	bm = dev_get_plat(bm_dev);
>   	desc = dev_get_uclass_plat(bm->blk);
>   	blknum = image_size >> desc->log2blksz;
> -	ret = blkmap_map_pmem(bm_dev, 0, blknum, image_addr);
> +	ret = blkmap_map_pmem(bm_dev, 0, blknum, image_addr, true);
>   	if (ret) {
>   		log_err("Unable to map %#llx at block %d : %d\n",
>   			(unsigned long long)image_addr, 0, ret);
> diff --git a/include/blkmap.h b/include/blkmap.h
> index d53095437fa..754d8671b01 100644
> --- a/include/blkmap.h
> +++ b/include/blkmap.h
> @@ -60,10 +60,12 @@ int blkmap_map_mem(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
>    * @blknr: Start block number of the mapping
>    * @blkcnt: Number of blocks to map
>    * @paddr: The target physical memory address of the mapping
> + * @preserve: Mapping intended to be preserved for subsequent stages,
> + *		like the OS (e.g. ISO installer)
>    * Returns: 0 on success, negative error code on failure
>    */
>   int blkmap_map_pmem(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
> -		    phys_addr_t paddr);
> +		    phys_addr_t paddr, bool preserve);
>   
>   /**
>    * blkmap_from_label() - Find blkmap from label