linux-kernel - [PATCH 2/4] nvmem: imx-ocotp-ele: fix reading from non zero offset

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Message-Id: <20241023-imx-ele-ocotp-fixes-v1-2-4adc00ce288f@pengutronix.de>
Date: Wed, 23 Oct 2024 10:12:29 +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 2/4] nvmem: imx-ocotp-ele: fix reading from non zero offset

In imx_ocotp_reg_read() the offset comes in as bytes and not as words.
This means we have to divide offset by 4 to get to the correct word
offset.

Also the incoming offset might not be word aligned. In order to read
from the OCOTP the driver aligns down the previous word boundary and
reads from there. This means we have to skip this alignment offset from
the temporary buffer when copying the data to the output buffer.

Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
---
 drivers/nvmem/imx-ocotp-ele.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/nvmem/imx-ocotp-ele.c b/drivers/nvmem/imx-ocotp-ele.c
index 2e186b7d3b040..b2d21a5f77bc1 100644
--- a/drivers/nvmem/imx-ocotp-ele.c
+++ b/drivers/nvmem/imx-ocotp-ele.c
@@ -71,12 +71,14 @@ static int imx_ocotp_reg_read(void *context, unsigned int offset, void *val, siz
 	u32 *buf;
 	void *p;
 	int i;
+	u8 skipbytes;
 
 	if (offset + bytes > priv->data->size)
 		bytes = priv->data->size - offset;
 
-	index = offset;
-	num_bytes = round_up(bytes, 4);
+	index = offset >> 2;
+	skipbytes = offset - (index << 2);
+	num_bytes = round_up(bytes + skipbytes, 4);
 	count = num_bytes >> 2;
 
 	p = kzalloc(num_bytes, GFP_KERNEL);
@@ -100,7 +102,7 @@ static int imx_ocotp_reg_read(void *context, unsigned int offset, void *val, siz
 			*buf++ = readl_relaxed(reg + (i << 2));
 	}
 
-	memcpy(val, (u8 *)p, bytes);
+	memcpy(val, ((u8 *)p) + skipbytes, bytes);
 
 	mutex_unlock(&priv->lock);
 

-- 
2.39.5