On Fri, 16 Feb 2024 at 02:22, Caleb Connolly <caleb.conno...@linaro.org> wrote:
>
> With just a few basic rules, we can generate the $fdtfile environment
> variable to match the format used in Linux. This uses the root
> compatible property inside u-boot, with specific handling for the
> Dragonboard845c which is a special case, and for the qrb robotics
> boards.
>
> This is known to work on supported platforms, and lets us avoid having a
> big lookup table.
>
> Reviewed-by: Neil Armstrong <neil.armstr...@linaro.org>
> Signed-off-by: Caleb Connolly <caleb.conno...@linaro.org>
> ---
> arch/arm/mach-snapdragon/board.c | 101
> +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 101 insertions(+)
>
Reviewed-by: Sumit Garg <sumit.g...@linaro.org>
-Sumit
> diff --git a/arch/arm/mach-snapdragon/board.c
> b/arch/arm/mach-snapdragon/board.c
> index f445bed3af00..5a859aabd5c4 100644
> --- a/arch/arm/mach-snapdragon/board.c
> +++ b/arch/arm/mach-snapdragon/board.c
> @@ -160,6 +160,106 @@ int board_init(void)
> return 0;
> }
>
> +/* Sets up the "board", and "soc" environment variables as well as
> constructing the devicetree
> + * path, with a few quirks to handle non-standard dtb filenames. This is not
> meant to be a
> + * comprehensive solution to automatically picking the DTB, but aims to be
> correct for the
> + * majority case. For most devices it should be possible to make this
> algorithm work by
> + * adjusting the root compatible property in the U-Boot DTS. Handling
> devices with multiple
> + * variants that are all supported by a single U-Boot image will require
> implementing device-
> + * specific detection.
> + */
> +static void configure_env(void)
> +{
> + const char *first_compat, *last_compat;
> + char *tmp;
> + char buf[32] = { 0 };
> + /*
> + * Most DTB filenames follow the scheme:
> qcom/<soc>-[vendor]-<board>.dtb
> + * The vendor is skipped when it's a Qualcomm reference board, or the
> + * db845c.
> + */
> + char dt_path[64] = { 0 };
> + int compat_count, ret;
> + ofnode root;
> +
> + root = ofnode_root();
> + /* This is almost always 2, but be explicit that we want the first
> and last compatibles
> + * not the first and second.
> + */
> + compat_count = ofnode_read_string_count(root, "compatible");
> + if (compat_count < 2) {
> + log_warning("%s: only one root compatible bailing!\n",
> __func__);
> + return;
> + }
> +
> + /* The most specific device compatible (e.g. "thundercomm,db845c") */
> + ret = ofnode_read_string_index(root, "compatible", 0, &first_compat);
> + if (ret < 0) {
> + log_warning("Can't read first compatible\n");
> + return;
> + }
> +
> + /* The last compatible is always the SoC compatible */
> + ret = ofnode_read_string_index(root, "compatible", compat_count - 1,
> &last_compat);
> + if (ret < 0) {
> + log_warning("Can't read second compatible\n");
> + return;
> + }
> +
> + /* Copy the second compat (e.g. "qcom,sdm845") into buf */
> + strlcpy(buf, last_compat, sizeof(buf) - 1);
> + tmp = buf;
> +
> + /* strsep() is destructive, it replaces the comma with a \0 */
> + if (!strsep(&tmp, ",")) {
> + log_warning("second compatible '%s' has no ','\n", buf);
> + return;
> + }
> +
> + /* tmp now points to just the "sdm845" part of the string */
> + env_set("soc", tmp);
> +
> + /* Now figure out the "board" part from the first compatible */
> + memset(buf, 0, sizeof(buf));
> + strlcpy(buf, first_compat, sizeof(buf) - 1);
> + tmp = buf;
> +
> + /* The Qualcomm reference boards (RBx, HDK, etc) */
> + if (!strncmp("qcom", buf, strlen("qcom"))) {
> + /*
> + * They all have the first compatible as "qcom,<soc>-<board>"
> + * (e.g. "qcom,qrb5165-rb5"). We extract just the part after
> + * the dash.
> + */
> + if (!strsep(&tmp, "-")) {
> + log_warning("compatible '%s' has no '-'\n", buf);
> + return;
> + }
> + /* tmp is now "rb5" */
> + env_set("board", tmp);
> + } else {
> + if (!strsep(&tmp, ",")) {
> + log_warning("compatible '%s' has no ','\n", buf);
> + return;
> + }
> + /* for thundercomm we just want the bit after the comma (e.g.
> "db845c"),
> + * for all other boards we replace the comma with a '-' and
> take both
> + * (e.g. "oneplus-enchilada")
> + */
> + if (!strncmp("thundercomm", buf, strlen("thundercomm"))) {
> + env_set("board", tmp);
> + } else {
> + *(tmp - 1) = '-';
> + env_set("board", buf);
> + }
> + }
> +
> + /* Now build the full path name */
> + snprintf(dt_path, sizeof(dt_path), "qcom/%s-%s.dtb",
> + env_get("soc"), env_get("board"));
> + env_set("fdtfile", dt_path);
> +}
> +
> void __weak qcom_late_init(void)
> {
> }
> @@ -188,6 +288,7 @@ int board_late_init(void)
> if (status)
> log_warning("%s: Failed to set run time variables\n",
> __func__);
>
> + configure_env();
> qcom_late_init();
>
> return 0;
>
> --
> 2.43.1
>
