linux-kernel - [PATCH 5.10 421/663] nvmem: core: skip child nodes not matching binding

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Date:   Mon,  1 Mar 2021 17:11:09 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Ahmad Fatoum <a.fatoum@...gutronix.de>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 421/663] nvmem: core: skip child nodes not matching binding

From: Ahmad Fatoum <a.fatoum@...gutronix.de>

[ Upstream commit 0445efacec75b85c2a3c176957ee050ba9be53f0 ]

The nvmem cell binding applies to all eeprom child nodes matching
"^.*@[0-9a-f]+$" without taking a compatible into account.

Linux drivers, like at24, are even more extensive and assume
_all_ at24 eeprom child nodes to be nvmem cells since e888d445ac33
("nvmem: resolve cells from DT at registration time").

Since df5f3b6f5357 ("dt-bindings: nvmem: stm32: new property for
data access"), the additionalProperties: True means it's Ok to have
other properties as long as they don't match "^.*@[0-9a-f]+$".

The barebox bootloader extends the MTD partitions binding to
EEPROM and can fix up following device tree node:

  &eeprom {
    partitions {
      compatible = "fixed-partitions";
    };
  };

This is allowed binding-wise, but drivers using nvmem_register()
like at24 will fail to parse because the function expects all child
nodes to have a reg property present. This results in the whole
EEPROM driver probe failing despite the device tree being correct.

Fix this by skipping nodes lacking a reg property instead of
returning an error. This effectively makes the drivers adhere
to the binding because all nodes with a unit address must have
a reg property and vice versa.

Fixes: e888d445ac33 ("nvmem: resolve cells from DT at registration time").
Signed-off-by: Ahmad Fatoum <a.fatoum@...gutronix.de>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Link: https://lore.kernel.org/r/20210129171430.11328-6-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/nvmem/core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 1a3460a8e73ab..9b6ab83956c3b 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -545,7 +545,9 @@ static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)

 	for_each_child_of_node(parent, child) {
 		addr = of_get_property(child, "reg", &len);
-		if (!addr || (len < 2 * sizeof(u32))) {
+		if (!addr)
+			continue;
+		if (len < 2 * sizeof(u32)) {
 			dev_err(dev, "nvmem: invalid reg on %pOF\n", child);
 			return -EINVAL;
 		}
-- 
2.27.0