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(+)
diff --git a/arch/arm/mach-snapdragon/board.c b/arch/arm/mach-snapdragon/board.c
index 3f51c4ab42d6..9d8684a21fa1 100644
--- a/arch/arm/mach-snapdragon/board.c
+++ b/arch/arm/mach-snapdragon/board.c
@@ -161,6 +161,106 @@ 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)
{
}
@@ -189,6 +289,7 @@ 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;
--
2.43.0
