rockchip: find U-boot proper boot device by inverting the logic that sets it

BOOT_DEVICE_* is set by spl_node_to_boot_device() depending on the block
device number associated with the MMC device the SPL used to load U-Boot
proper from. It is NOT related to the mmc alias in the Device Tree.

For SPI flashes, all SPI flashes will return BOOT_DEVICE_SPI so there's
currently no way to know from which one the SPL loaded U-Boot proper
from. Therefore, let's just find the first valid candidate in
/chosen/u-boot,spl-boot-order that is a SPI flash and return that path.
This is a best effort.

While the original implementation may have worked, using the exact same
mechanism but in inverted fashion makes it less likely to have
surprising corner-cases or side-effects.

A nice side-effect is that all existing and future Rockchip SoCs now
automatically have their /chosen/u-boot,spl-boot-device set.

Cc: Quentin Schulz <foss+uboot@0leil.net>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Signed-off-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>

arch/arm/mach-rockchip/px30/px30.c

@@ -443,10 +443,3 @@ void board_debug_uart_init(void)
 #endif /* CONFIG_DEBUG_UART_BASE && CONFIG_DEBUG_UART_BASE == ... */
 }
 #endif /* CONFIG_DEBUG_UART_BOARD_INIT */
-
-#if defined(CONFIG_SPL_BUILD) && !defined(CONFIG_TPL_BUILD)
-const char * const spl_boot_devices[BOOT_DEVICE_NONE + 1] = {
-	[BOOT_DEVICE_MMC2] = "/mmc@ff370000",
-	[BOOT_DEVICE_MMC1] = "/mmc@ff390000",
-};
-#endif

arch/arm/mach-rockchip/rk3399/rk3399.c

@@ -175,12 +175,6 @@ void board_debug_uart_init(void)
 #endif
 
 #if defined(CONFIG_SPL_BUILD) && !defined(CONFIG_TPL_BUILD)
-const char * const spl_boot_devices[BOOT_DEVICE_NONE + 1] = {
-	[BOOT_DEVICE_MMC2] = "/mmc@fe320000",
-	[BOOT_DEVICE_MMC1] = "/mmc@fe330000",
-	[BOOT_DEVICE_SPI] = "/spi@ff1d0000/flash@0",
-};
-
 static void rk3399_force_power_on_reset(void)
 {
 	ofnode node;

arch/arm/mach-rockchip/spl-boot-order.c

@@ -10,6 +10,7 @@
 #include <mmc.h>
 #include <spl.h>
 #include <asm/global_data.h>
+#include <dm/uclass-internal.h>
 
 #if CONFIG_IS_ENABLED(OF_LIBFDT)
 /**
@@ -163,30 +164,91 @@ void board_boot_order(u32 *spl_boot_list)
 		spl_boot_list[0] = spl_boot_device();
 }
 
-__weak const char * const spl_boot_devices[BOOT_DEVICE_NONE + 1] = {};
-
-const char *spl_decode_boot_device(u32 boot_device)
+int spl_decode_boot_device(u32 boot_device, char *buf, size_t buflen)
 {
-	const char *spl_bootdevice_ofpath = NULL;
+	struct udevice *dev;
+#if CONFIG_IS_ENABLED(BLK)
+	int dev_num;
+#endif
+	int ret;
 
-	if (boot_device < ARRAY_SIZE(spl_boot_devices))
-		spl_bootdevice_ofpath = spl_boot_devices[boot_device];
+	if (boot_device == BOOT_DEVICE_SPI) {
+		/* Revert spl_node_to_boot_device() logic to find appropriate SPI flash device */
 
-	if (spl_bootdevice_ofpath)
-		debug("%s: spl_bootdevice_id %x maps to '%s'\n",
-		      __func__, boot_device, spl_bootdevice_ofpath);
-	else
-		debug("%s: failed to resolve spl_bootdevice_id %x\n",
-		      __func__, boot_device);
+		/*
+		 * Devices with multiple SPI flash devices will take the first SPI flash found in
+		 * /chosen/u-boot,spl-boot-order.
+		 */
+		const void *blob = gd->fdt_blob;
+		int chosen_node = fdt_path_offset(blob, "/chosen");
+		int elem;
+		int node;
+		const char *conf;
 
-	return spl_bootdevice_ofpath;
+		if (chosen_node < 0) {
+			debug("%s: /chosen not found\n", __func__);
+			return -ENODEV;
+		}
+
+		for (elem = 0;
+		     (conf = fdt_stringlist_get(blob, chosen_node,
+						"u-boot,spl-boot-order", elem, NULL));
+		     elem++) {
+			const char *alias;
+
+			/* Handle the case of 'same device the SPL was loaded from' */
+			if (strncmp(conf, "same-as-spl", 11) == 0) {
+				conf = board_spl_was_booted_from();
+				if (!conf)
+					continue;
+			}
+
+			/* First check if the list element is an alias */
+			alias = fdt_get_alias(blob, conf);
+			if (alias)
+				conf = alias;
+
+			/* Try to resolve the config item (or alias) as a path */
+			node = fdt_path_offset(blob, conf);
+			if (node < 0) {
+				debug("%s: could not find %s in FDT\n", __func__, conf);
+				continue;
+			}
+
+			ret = uclass_find_device_by_of_offset(UCLASS_SPI_FLASH, node, &dev);
+			if (ret) {
+				debug("%s: could not find udevice for %s\n", __func__, conf);
+				continue;
+			}
+
+			return ofnode_get_path(dev_ofnode(dev), buf, buflen);
+		}
+
+		return -ENODEV;
+	}
+
+#if CONFIG_IS_ENABLED(BLK)
+	dev_num = (boot_device == BOOT_DEVICE_MMC1) ? 0 : 1;
+
+	ret = blk_find_device(UCLASS_MMC, dev_num, &dev);
+	if (ret) {
+		debug("%s: could not find blk device for MMC device %d: %d\n",
+		      __func__, dev_num, ret);
+		return ret;
+	}
+
+	dev = dev_get_parent(dev);
+	return ofnode_get_path(dev_ofnode(dev), buf, buflen);
+#else
+	return -ENODEV;
+#endif
 }
 
 void spl_perform_fixups(struct spl_image_info *spl_image)
 {
 	void *blob = spl_image_fdt_addr(spl_image);
-	const char *boot_ofpath;
-	int chosen;
+	char boot_ofpath[512];
+	int chosen, ret;
 
 	/*
 	 * Inject the ofpath of the device the full U-Boot (or Linux in
@@ -196,9 +258,9 @@ void spl_perform_fixups(struct spl_image_info *spl_image)
 	if (!blob)
 		return;
 
-	boot_ofpath = spl_decode_boot_device(spl_image->boot_device);
-	if (!boot_ofpath) {
-		pr_err("%s: could not map boot_device to ofpath\n", __func__);
+	ret = spl_decode_boot_device(spl_image->boot_device, boot_ofpath, sizeof(boot_ofpath));
+	if (ret) {
+		pr_err("%s: could not map boot_device to ofpath: %d\n", __func__, ret);
 		return;
 	}