linux-kernel - [PATCH 4/4] nvmem: imx-ocotp-ele: set word length to 1

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Message-Id: <20241023-imx-ele-ocotp-fixes-v1-4-4adc00ce288f@pengutronix.de>
Date: Wed, 23 Oct 2024 10:12:31 +0200
From: Sascha Hauer <s.hauer@...gutronix.de>
To: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>, 
 Shawn Guo <shawnguo@...nel.org>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 Fabio Estevam <festevam@...il.com>
Cc: imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, Sascha Hauer <s.hauer@...gutronix.de>
Subject: [PATCH 4/4] nvmem: imx-ocotp-ele: set word length to 1

The ELE hardware internally has a word length of 4. However, among other
things we store MAC addresses in the ELE OCOTP. With a length of 6 bytes
these are naturally unaligned to the word length. Therefore we must
support unaligned reads in reg_read() and indeed it works properly when
reg_read() is called via nvmem_reg_read(). Setting the word size to 4
has the only visible effect that doing unaligned reads from userspace
via bin_attr_nvmem_read() do not work because they are rejected by that
function.

Given that we have to abstract from word accesses to byte accesses in
the driver, set the word size to 1. This allows bytewise accesses from
userspace to be able to test what the driver has to support anyway.

Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
---
 drivers/nvmem/imx-ocotp-ele.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvmem/imx-ocotp-ele.c b/drivers/nvmem/imx-ocotp-ele.c
index 422a6d53b10ef..ca6dd71d8a2e2 100644
--- a/drivers/nvmem/imx-ocotp-ele.c
+++ b/drivers/nvmem/imx-ocotp-ele.c
@@ -153,7 +153,7 @@ static int imx_ele_ocotp_probe(struct platform_device *pdev)
 	priv->config.owner = THIS_MODULE;
 	priv->config.size = priv->data->size;
 	priv->config.reg_read = priv->data->reg_read;
-	priv->config.word_size = 4;
+	priv->config.word_size = 1;
 	priv->config.stride = 1;
 	priv->config.priv = priv;
 	priv->config.read_only = true;

-- 
2.39.5