linux-kernel - [PATCH 1/9] mtd: core: add nvmem

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Message-Id: <20240701-b4-v6-10-topic-usbc-tcpci-v1-1-3fd5f4a193cc@pengutronix.de>
Date: Mon, 01 Jul 2024 15:53:40 +0200
From: Marco Felsch <m.felsch@...gutronix.de>
To: Miquel Raynal <miquel.raynal@...tlin.com>, 
 Richard Weinberger <richard@....at>, Vignesh Raghavendra <vigneshr@...com>, 
 Arnd Bergmann <arnd@...db.de>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Bartosz Golaszewski <brgl@...ev.pl>, Russell King <linux@...linux.org.uk>, 
 Joel Stanley <joel@....id.au>, Andrew Jeffery <andrew@...econstruct.com.au>, 
 Nicolas Ferre <nicolas.ferre@...rochip.com>, 
 Alexandre Belloni <alexandre.belloni@...tlin.com>, 
 Claudiu Beznea <claudiu.beznea@...on.dev>, Shawn Guo <shawnguo@...nel.org>, 
 Sascha Hauer <s.hauer@...gutronix.de>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 Fabio Estevam <festevam@...il.com>, Vladimir Zapolskiy <vz@...ia.com>, 
 Andrew Lunn <andrew@...n.ch>, Gregory Clement <gregory.clement@...tlin.com>, 
 Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>, 
 Tony Lindgren <tony@...mide.com>, 
 Geert Uytterhoeven <geert+renesas@...der.be>, 
 Magnus Damm <magnus.damm@...il.com>, Dinh Nguyen <dinguyen@...nel.org>, 
 Thierry Reding <thierry.reding@...il.com>, 
 Jonathan Hunter <jonathanh@...dia.com>, 
 Jonathan Neuschäfer <j.neuschaefer@....net>, 
 Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>, 
 Christophe Leroy <christophe.leroy@...roup.eu>, 
 "Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>, 
 Thomas Bogendoerfer <tsbogend@...ha.franken.de>, 
 Huacai Chen <chenhuacai@...nel.org>, WANG Xuerui <kernel@...0n.name>
Cc: linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 linux-i2c@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 linux-aspeed@...ts.ozlabs.org, imx@...ts.linux.dev, 
 linux-omap@...r.kernel.org, linux-renesas-soc@...r.kernel.org, 
 linux-tegra@...r.kernel.org, openbmc@...ts.ozlabs.org, 
 linuxppc-dev@...ts.ozlabs.org, linux-mips@...r.kernel.org, 
 loongarch@...ts.linux.dev, Marco Felsch <m.felsch@...gutronix.de>
Subject: [PATCH 1/9] mtd: core: add nvmem_write support

The MTD framework does support the NVMEM framework already but only the
read support was implemented. This commit adds the write support if the
MTD device supports writing (MTD_WRITEABLE is set).

Signed-off-by: Marco Felsch <m.felsch@...gutronix.de>
---
 drivers/mtd/mtdcore.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 724f917f91ba..dcd97e59425e 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -544,6 +544,20 @@ static int mtd_nvmem_reg_read(void *priv, unsigned int offset,
 	return retlen == bytes ? 0 : -EIO;
 }

+static int mtd_nvmem_reg_write(void *priv, unsigned int offset,
+			       void *val, size_t bytes)
+{
+	struct mtd_info *mtd = priv;
+	size_t retlen;
+	int err;
+
+	err = mtd_write(mtd, offset, bytes, &retlen, val);
+	if (err && err != -EUCLEAN)
+		return err;
+
+	return retlen == bytes ? 0 : -EIO;
+}
+
 static int mtd_nvmem_add(struct mtd_info *mtd)
 {
 	struct device_node *node = mtd_get_of_node(mtd);
@@ -555,10 +569,11 @@ static int mtd_nvmem_add(struct mtd_info *mtd)
 	config.owner = THIS_MODULE;
 	config.add_legacy_fixed_of_cells = of_device_is_compatible(node, "nvmem-cells");
 	config.reg_read = mtd_nvmem_reg_read;
+	config.reg_write = mtd_nvmem_reg_write;
 	config.size = mtd->size;
 	config.word_size = 1;
 	config.stride = 1;
-	config.read_only = true;
+	config.read_only = !(mtd->flags & MTD_WRITEABLE);
 	config.root_only = true;
 	config.ignore_wp = true;
 	config.priv = mtd;

-- 
2.39.2