On Mon, May 26, 2025 at 04:38:12PM +0200, Michael Tretter wrote:
> Board code in the PBL may use fdt_fixup_mem() to write the base
> addresses and sizes of detected SDRAM to the fdt before passing the fdt
> to other software like the TF-A and OP-TEE.
>
> This is implemented on the fdt to avoid that the PBL needs to unpack the
> device tree, use the of function for manipulation and repack the device
> tree.
>
> Signed-off-by: Michael Tretter <m.tret...@pengutronix.de>
> ---
> include/pbl.h | 1 +
> pbl/fdt.c | 71
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 72 insertions(+)
>
> diff --git a/include/pbl.h b/include/pbl.h
> index
> abac3458593af2cec972a54ce9fb69e344179670..b330010562c4aba5fccbb4c421bb95291fa0bea1
> 100644
> --- a/include/pbl.h
> +++ b/include/pbl.h
> @@ -17,6 +17,7 @@ extern unsigned long free_mem_end_ptr;
> void pbl_barebox_uncompress(void *dest, void *compressed_start, unsigned int
> len);
>
> void fdt_find_mem(const void *fdt, unsigned long *membase, unsigned long
> *memsize);
> +int fdt_fixup_mem(void *fdt, unsigned long membase[], unsigned long
> memsize[], size_t num);
>
> struct fdt_device_id {
> const char *compatible;
> diff --git a/pbl/fdt.c b/pbl/fdt.c
> index
> 3b1783152a8cb81f3eda1187b2f7bf998c4addf4..40564952acfcd88bef050966720e76b7378bc720
> 100644
> --- a/pbl/fdt.c
> +++ b/pbl/fdt.c
> @@ -2,6 +2,7 @@
> #include <linux/libfdt.h>
> #include <pbl.h>
> #include <linux/printk.h>
> +#include <stdio.h>
>
> static const __be32 *fdt_parse_reg(const __be32 *reg, uint32_t n,
> uint64_t *val)
> @@ -73,6 +74,76 @@ void fdt_find_mem(const void *fdt, unsigned long *membase,
> unsigned long *memsiz
> while (1);
> }
>
> +int fdt_fixup_mem(void *fdt, unsigned long membase[], unsigned long
> memsize[], size_t num)
> +{
> + int na, ns;
> + int node, root;
> + int err;
> + int i;
> +
> + err = fdt_check_header(fdt);
> + if (err != 0) {
> + pr_err("Invalid device tree blob\n");
> + return err;
> + }
> +
> + root = fdt_path_offset(fdt, "/");
> + if (root < 0) {
> + pr_err("Cannot find root node: %s\n", fdt_strerror(root));
> + return root;
> + }
> +
> + na = fdt_address_cells(fdt, root);
> + if (na < 0) {
> + pr_err("Cannot find #address-cells property: %s\n",
> + fdt_strerror(na));
> + return na;
> + }
> +
> + ns = fdt_size_cells(fdt, root);
> + if (ns < 0) {
> + pr_err("Cannot find #size-cells property: %s\n",
> + fdt_strerror(ns));
> + return ns;
> + }
fdt_appendprop_addrrange() handles #address-cells and #size-cells
internally, consequently na and ns are not used in this function.
> +
> + for (i = 0; i < num; i++) {
> + char name[32];
> +
> + if (membase[i] == 0 || memsize[i] == 0)
> + continue;
> +
> + snprintf(name, sizeof(name), "memory@%lx", membase[i]);
> + node = fdt_add_subnode(fdt, root, name);
There are some pitfalls in this function when the device tree already
has memory nodes. It seems fdt_add_subnode() returns -FDT_ERR_EXISTS
in case the node already exists. You should likely check that.
Some device trees have a plain "memory" node without the @address
postfix. These should be deleted before adding other memory nodes.
> + if (node < 0) {
> + pr_err("Cannot to add node %s: %s\n",
> + name, fdt_strerror(node));
> + err = node;
> + break;
> + }
> +
> + pr_debug("Add memory node %s (0x%lx, size 0x%lx)\n",
> + name, membase[i], memsize[i]);
> +
> + err = fdt_setprop(fdt, node,
> + "device_type", "memory", sizeof("memory"));
> + if (err < 0) {
> + pr_err("%s: Cannot set device_type: %s\n",
> + name, fdt_strerror(err));
> + return err;
> + }
> +
> + err = fdt_appendprop_addrrange(fdt, root, node, "reg",
> membase[i], memsize[i]);
This sounds like it appends the range to ranges already existing in the
node. Do you have to call fdt_delprop(..., "reg") beforehand?
Sascha
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