linux-kernel - [PATCH V2 3/5] misc: eeprom: at24: Support custom device names for AT24 EEPROMs

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Date:   Wed, 16 Sep 2020 10:49:50 +0100
From:   Jon Hunter <jonathanh@...dia.com>
To:     Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Rob Herring <robh+dt@...nel.org>,
        Thierry Reding <thierry.reding@...il.com>
CC:     <linux-i2c@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        Jon Hunter <jonathanh@...dia.com>
Subject: [PATCH V2 3/5] misc: eeprom: at24: Support custom device names for AT24 EEPROMs

By using the label property, a more descriptive name can be populated
for AT24 EEPROMs NVMEM device. Update the AT24 driver to check to see
if the label property is present and if so, use this as the name for
NVMEM device. Please note that when the 'label' property is present for
the AT24 EEPROM, we do not want the NVMEM driver to append the 'devid'
to the name and so the nvmem_config.id is initialised to
NVMEM_DEVID_NONE.

Signed-off-by: Jon Hunter <jonathanh@...dia.com>
---
 drivers/misc/eeprom/at24.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index f76624b5c033..305f2e13107b 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -713,9 +713,28 @@ static int at24_probe(struct i2c_client *client)
 			return err;
 	}
 
-	nvmem_config.name = dev_name(dev);
+	/*
+	 * If the 'label' property is not present for the AT24 EEPROM,
+	 * then nvmem_config.id is initialised to NVMEM_DEVID_AUTO,
+	 * and this will append the 'devid' to the name of the NVMEM
+	 * device. This is purely legacy and the AT24 driver has always
+	 * defaulted to this. However, if the 'label' property is
+	 * present then this means that the name is specified by the
+	 * firmware and this name should be used verbatim and so it is
+	 * not necessary to append the 'devid'.
+	 */
+	if (device_property_present(dev, "label")) {
+		nvmem_config.id = NVMEM_DEVID_NONE;
+		err = device_property_read_string(dev, "label",
+						  &nvmem_config.name);
+		if (err)
+			return err;
+	} else {
+		nvmem_config.id = NVMEM_DEVID_AUTO;
+		nvmem_config.name = dev_name(dev);
+	}
+
 	nvmem_config.dev = dev;
-	nvmem_config.id = NVMEM_DEVID_AUTO;
 	nvmem_config.read_only = !writable;
 	nvmem_config.root_only = !(flags & AT24_FLAG_IRUGO);
 	nvmem_config.owner = THIS_MODULE;
-- 
2.25.1