linux-kernel - [PATCH 2/7] nvmem: core: round up to word

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Message-Id: <20250510-nvmem-dt-v1-2-eccfa6e33f6a@svenpeter.dev>
Date: Sat, 10 May 2025 07:44:42 +0000
From: Sven Peter via B4 Relay <devnull+sven.svenpeter.dev@...nel.org>
To: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>, 
 Janne Grunau <j@...nau.net>, Alyssa Rosenzweig <alyssa@...enzweig.io>, 
 Neal Gompa <neal@...pa.dev>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>
Cc: linux-kernel@...r.kernel.org, asahi@...ts.linux.dev, 
 linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org, 
 Sven Peter <sven@...npeter.dev>
Subject: [PATCH 2/7] nvmem: core: round up to word_size

From: Sven Peter <sven@...npeter.dev>

Some nvmem controllers like Apple's eFuses or Nintendo's OTP have a cell
word size that's larger than one byte and cannot read anything smaller.
Round up cell->bytes correctly when accessing a subset of bits.

Signed-off-by: Sven Peter <sven@...npeter.dev>
---
 drivers/nvmem/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 1bd39b12c21a86b9b135be95251a52a10543c2ea..02081c93fa467e5448bd78a4920072d437365fb9 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -595,8 +595,8 @@ static int nvmem_cell_info_to_nvmem_cell_entry_nodup(struct nvmem_device *nvmem,
 	cell->np = info->np;
 
 	if (cell->nbits)
-		cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
-					   BITS_PER_BYTE);
+		cell->bytes = round_up(DIV_ROUND_UP(cell->nbits + cell->bit_offset,
+					   BITS_PER_BYTE), nvmem->word_size);
 
 	if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 		dev_err(&nvmem->dev,

-- 
2.34.1