linux-kernel - [PATCH v2 09/16] nvmem: microchip-otpc: Avoid reading a write-only register

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Message-Id: <20250210165050.496486-1-ada@thorsis.com>
Date: Mon, 10 Feb 2025 17:50:47 +0100
From: Alexander Dahl <ada@...rsis.com>
To: Claudiu Beznea <claudiu.beznea@...on.dev>
Cc: Nicolas Ferre <nicolas.ferre@...rochip.com>,
	Ryan Wanner <ryan.wanner@...rochip.com>,
	linux-arm-kernel@...ts.infradead.org,
	devicetree@...r.kernel.org,
	linux-clk@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [PATCH v2 09/16] nvmem: microchip-otpc: Avoid reading a write-only register

The OTPC Control Register (OTPC_CR) has just write-only members.
Reading from that register leads to a warning in OTPC Write Protection
Status Register (OTPC_WPSR) in field Software Error Type (SWETYP) of
type READ_WO (A write-only register has been read (warning).)

Just create the register write content from scratch is sufficient here.

Signed-off-by: Alexander Dahl <ada@...rsis.com>
Fixes: 98830350d3fc ("nvmem: microchip-otpc: add support")
---

Notes:
    v2:
    - Add Fixes tag
    - Remove temporary variable usage
    - Reword misleading subject (s/writing/reading/)

 drivers/nvmem/microchip-otpc.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/nvmem/microchip-otpc.c b/drivers/nvmem/microchip-otpc.c
index df979e8549fdb..e2851c63cc0b4 100644
--- a/drivers/nvmem/microchip-otpc.c
+++ b/drivers/nvmem/microchip-otpc.c
@@ -82,9 +82,7 @@ static int mchp_otpc_prepare_read(struct mchp_otpc *otpc,
 	writel_relaxed(tmp, otpc->base + MCHP_OTPC_MR);
 
 	/* Set read. */
-	tmp = readl_relaxed(otpc->base + MCHP_OTPC_CR);
-	tmp |= MCHP_OTPC_CR_READ;
-	writel_relaxed(tmp, otpc->base + MCHP_OTPC_CR);
+	writel_relaxed(MCHP_OTPC_CR_READ, otpc->base + MCHP_OTPC_CR);
 
 	/* Wait for packet to be transferred into temporary buffers. */
 	return read_poll_timeout(readl_relaxed, tmp, !(tmp & MCHP_OTPC_SR_READ),
-- 
2.39.5