From 045b14ca5c3657dc6c16afa97a00dba17286d3e8 Mon Sep 17 00:00:00 2001 From: "Rob Herring (Arm)" Date: Wed, 6 Nov 2024 11:10:27 -0600 Subject: [PATCH] of: WARN on deprecated #address-cells/#size-cells handling While OpenFirmware originally allowed walking parent nodes and default root values for #address-cells and #size-cells, FDT has long required explicit values. It's been a warning in dtc for the root node since the beginning (2005) and for any parent node since 2007. Of course, not all FDT uses dtc, but that should be the majority by far. The various extracted OF devicetrees I have dating back to the 1990s (various PowerMac, OLPC, PASemi Nemo) all have explicit root node properties. The warning is disabled for Sparc as there are known systems relying on default root node values. Link: https://lore.kernel.org/r/20241106171028.3830266-1-robh@kernel.org Signed-off-by: Rob Herring (Arm) --- drivers/of/base.c | 28 ++++++++++++++++++++++------ drivers/of/fdt.c | 4 ++-- 2 files changed, 24 insertions(+), 8 deletions(-) diff --git a/drivers/of/base.c b/drivers/of/base.c index d94efee4a7fc..a8b0c42bdc8e 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -87,15 +87,25 @@ static bool __of_node_is_type(const struct device_node *np, const char *type) return np && match && type && !strcmp(match, type); } +#define EXCLUDED_DEFAULT_CELLS_PLATFORMS ( \ + IS_ENABLED(CONFIG_SPARC) \ +) + int of_bus_n_addr_cells(struct device_node *np) { u32 cells; - for (; np; np = np->parent) + for (; np; np = np->parent) { if (!of_property_read_u32(np, "#address-cells", &cells)) return cells; - - /* No #address-cells property for the root node */ + /* + * Default root value and walking parent nodes for "#address-cells" + * is deprecated. Any platforms which hit this warning should + * be added to the excluded list. + */ + WARN_ONCE(!EXCLUDED_DEFAULT_CELLS_PLATFORMS, + "Missing '#address-cells' in %pOF\n", np); + } return OF_ROOT_NODE_ADDR_CELLS_DEFAULT; } @@ -112,11 +122,17 @@ int of_bus_n_size_cells(struct device_node *np) { u32 cells; - for (; np; np = np->parent) + for (; np; np = np->parent) { if (!of_property_read_u32(np, "#size-cells", &cells)) return cells; - - /* No #size-cells property for the root node */ + /* + * Default root value and walking parent nodes for "#size-cells" + * is deprecated. Any platforms which hit this warning should + * be added to the excluded list. + */ + WARN_ONCE(!EXCLUDED_DEFAULT_CELLS_PLATFORMS, + "Missing '#size-cells' in %pOF\n", np); + } return OF_ROOT_NODE_SIZE_CELLS_DEFAULT; } diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c index d3ecf2bdd202..0121100372b4 100644 --- a/drivers/of/fdt.c +++ b/drivers/of/fdt.c @@ -937,12 +937,12 @@ int __init early_init_dt_scan_root(void) dt_root_addr_cells = OF_ROOT_NODE_ADDR_CELLS_DEFAULT; prop = of_get_flat_dt_prop(node, "#size-cells", NULL); - if (prop) + if (!WARN(!prop, "No '#size-cells' in root node\n")) dt_root_size_cells = be32_to_cpup(prop); pr_debug("dt_root_size_cells = %x\n", dt_root_size_cells); prop = of_get_flat_dt_prop(node, "#address-cells", NULL); - if (prop) + if (!WARN(!prop, "No '#address-cells' in root node\n")) dt_root_addr_cells = be32_to_cpup(prop); pr_debug("dt_root_addr_cells = %x\n", dt_root_addr_cells);