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.
Signed-off-by: Caleb Connolly caleb.connolly@linaro.org --- arch/arm/mach-snapdragon/board.c | 101 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 101 insertions(+)
diff --git a/arch/arm/mach-snapdragon/board.c b/arch/arm/mach-snapdragon/board.c index 765a2c2a95fc..d142f2fddf8e 100644 --- a/arch/arm/mach-snapdragon/board.c +++ b/arch/arm/mach-snapdragon/board.c @@ -111,6 +111,106 @@ 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) { } @@ -141,6 +241,7 @@ 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;