From: Michael Brown <mcb30@ipxe.org>
Date: Fri, 30 May 2025 15:39:10 +0000 (+0100)
Subject: [dt] Locate parent node at point of use in dt_ioremap()
X-Git-Url: http://git.ipfire.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=bb2011241fcf15de4edd962fe9656e513ad19174;p=thirdparty%2Fipxe.git

[dt] Locate parent node at point of use in dt_ioremap()

We currently rely on the recursive nature of devicetree bus probing to
obtain the region cell size specification from the parent device.
This blocks the possibility of creating a standalone console device
based on /chosen/stdout-path before probing the whole bus.

Fix by using fdt_parent() to locate the parent device at the point of
use within dt_ioremap().

Signed-off-by: Michael Brown <mcb30@ipxe.org>
---

diff --git a/src/drivers/bus/devtree.c b/src/drivers/bus/devtree.c
index 55f68ee33..796fe56a0 100644
--- a/src/drivers/bus/devtree.c
+++ b/src/drivers/bus/devtree.c
@@ -54,16 +54,25 @@ static void dt_remove_children ( struct dt_device *parent );
  */
 void * dt_ioremap ( struct dt_device *dt, unsigned int offset,
 		    unsigned int index, size_t len ) {
-	struct dt_device *parent =
-		container_of ( dt->dev.parent, struct dt_device, dev );
-	struct fdt_reg_cells *regs = &parent->regs;
+	struct fdt_reg_cells regs;
+	unsigned int parent;
 	uint64_t address;
 	uint64_t size;
 	void *io_addr;
 	int rc;
 
+	/* Get parent node */
+	if ( ( rc = fdt_parent ( &sysfdt, offset, &parent ) ) != 0 ) {
+		DBGC ( dt, "DT %s could not locate parent: %s\n",
+		       dt->path, strerror ( rc ) );
+		return NULL;
+	}
+
+	/* Read #address-cells and #size-cells, if present */
+	fdt_reg_cells ( &sysfdt, parent, &regs );
+
 	/* Read address */
-	if ( ( rc = fdt_reg_address ( &sysfdt, offset, regs, index,
+	if ( ( rc = fdt_reg_address ( &sysfdt, offset, &regs, index,
 				      &address ) ) != 0 ) {
 		DBGC ( dt, "DT %s could not read region %d address: %s\n",
 		       dt->path, index, strerror ( rc ) );
@@ -72,8 +81,8 @@ void * dt_ioremap ( struct dt_device *dt, unsigned int offset,
 
 	/* Read size (or assume sufficient, if tree specifies no sizes) */
 	size = len;
-	if ( regs->size_cells &&
-	     ( ( rc = fdt_reg_size ( &sysfdt, offset, regs, index,
+	if ( regs.size_cells &&
+	     ( ( rc = fdt_reg_size ( &sysfdt, offset, &regs, index,
 				     &size ) ) != 0 ) ) {
 		DBGC ( dt, "DT %s could not read region %d size: %s\n",
 		       dt->path, index, strerror ( rc ) );
@@ -222,9 +231,6 @@ static int dt_probe_node ( struct dt_device *parent, unsigned int offset,
 	INIT_LIST_HEAD ( &dt->dev.children );
 	list_add_tail ( &dt->dev.siblings, &dt->dev.parent->children );
 
-	/* Read #address-cells and #size-cells, if present */
-	fdt_reg_cells ( &sysfdt, offset, &dt->regs );
-
 	/* Probe device */
 	if ( ( rc = dt_probe ( dt, offset ) ) != 0 )
 		goto err_probe;
diff --git a/src/include/ipxe/devtree.h b/src/include/ipxe/devtree.h
index 6e9286af4..46d8b5d86 100644
--- a/src/include/ipxe/devtree.h
+++ b/src/include/ipxe/devtree.h
@@ -25,9 +25,6 @@ struct dt_device {
 	struct dt_driver *driver;
 	/** Driver-private data */
 	void *priv;
-
-	/** Register cell size specification */
-	struct fdt_reg_cells regs;
 };
 
 /** A devicetree driver */