Lantiq PEF2256 framer has some little differences in behaviour
depending on its version.

Add a sysfs attribute to allow user applications to know the
version.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
v3:
- Added documentation Documentation/ABI/testing/sysfs-driver-framer-pef2256

v2: https://lore.kernel.org/all/2e01f4ed00d0c1475863ffa30bdc2503f330b688.1758089951.git.christophe.leroy@csgroup.eu
- Split version_show() prototype to 80 chars
- Make DEVICE_ATTR_RO(version) static

v1: https://lore.kernel.org/all/f9aaa89946f1417dc0a5e852702410453e816dbc.1757754689.git.christophe.leroy@csgroup.eu/
---
 .../ABI/testing/sysfs-driver-framer-pef2256   |  8 +++++++
 drivers/net/wan/framer/pef2256/pef2256.c      | 24 +++++++++++++++----
 2 files changed, 27 insertions(+), 5 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-driver-framer-pef2256

diff --git a/Documentation/ABI/testing/sysfs-driver-framer-pef2256 b/Documentation/ABI/testing/sysfs-driver-framer-pef2256
new file mode 100644
index 000000000000..ead1ae84ef2a
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-framer-pef2256
@@ -0,0 +1,8 @@
+What:		/sys/bus/platform/devices/xxx/version
+Date:		Sep 2025
+Contact:	netdev@vger.kernel.org
+Description:	Reports the version of the PEF2256 framer
+
+		Access: Read
+
+		Valid values: Represented as string
diff --git a/drivers/net/wan/framer/pef2256/pef2256.c b/drivers/net/wan/framer/pef2256/pef2256.c
index 1e4c8e85d598..a2166b424428 100644
--- a/drivers/net/wan/framer/pef2256/pef2256.c
+++ b/drivers/net/wan/framer/pef2256/pef2256.c
@@ -37,6 +37,7 @@ struct pef2256 {
 	struct device *dev;
 	struct regmap *regmap;
 	enum pef2256_version version;
+	const char *version_txt;
 	struct clk *mclk;
 	struct clk *sclkr;
 	struct clk *sclkx;
@@ -114,6 +115,16 @@ enum pef2256_version pef2256_get_version(struct pef2256 *pef2256)
 }
 EXPORT_SYMBOL_GPL(pef2256_get_version);
 
+static ssize_t version_show(struct device *dev, struct device_attribute *attr,
+			    char *buf)
+{
+	struct pef2256 *pef2256 = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%s\n", pef2256->version_txt);
+}
+
+static DEVICE_ATTR_RO(version);
+
 enum pef2256_gcm_config_item {
 	PEF2256_GCM_CONFIG_1544000 = 0,
 	PEF2256_GCM_CONFIG_2048000,
@@ -697,7 +708,6 @@ static int pef2256_probe(struct platform_device *pdev)
 	unsigned long sclkr_rate, sclkx_rate;
 	struct framer_provider *framer_provider;
 	struct pef2256 *pef2256;
-	const char *version_txt;
 	void __iomem *iomem;
 	int ret;
 	int irq;
@@ -763,18 +773,18 @@ static int pef2256_probe(struct platform_device *pdev)
 	pef2256->version = pef2256_get_version(pef2256);
 	switch (pef2256->version) {
 	case PEF2256_VERSION_1_2:
-		version_txt = "1.2";
+		pef2256->version_txt = "1.2";
 		break;
 	case PEF2256_VERSION_2_1:
-		version_txt = "2.1";
+		pef2256->version_txt = "2.1";
 		break;
 	case PEF2256_VERSION_2_2:
-		version_txt = "2.2";
+		pef2256->version_txt = "2.2";
 		break;
 	default:
 		return -ENODEV;
 	}
-	dev_info(pef2256->dev, "Version %s detected\n", version_txt);
+	dev_info(pef2256->dev, "Version %s detected\n", pef2256->version_txt);
 
 	ret = pef2556_of_parse(pef2256, np);
 	if (ret)
@@ -835,6 +845,8 @@ static int pef2256_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	device_create_file(pef2256->dev, &dev_attr_version);
+
 	return 0;
 }
 
@@ -849,6 +861,8 @@ static void pef2256_remove(struct platform_device *pdev)
 	pef2256_write8(pef2256, PEF2256_IMR3, 0xff);
 	pef2256_write8(pef2256, PEF2256_IMR4, 0xff);
 	pef2256_write8(pef2256, PEF2256_IMR5, 0xff);
+
+	device_remove_file(pef2256->dev, &dev_attr_version);
 }
 
 static const struct of_device_id pef2256_id_table[] = {
-- 
2.49.0

Hi Christophe,

On Wed, 24 Sep 2025 17:06:47 +0200
Christophe Leroy <christophe.leroy@csgroup.eu> wrote:

> Lantiq PEF2256 framer has some little differences in behaviour
> depending on its version.
> 
> Add a sysfs attribute to allow user applications to know the
> version.
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> ---

Acked-by: Herve Codina <herve.codina@bootlin.com>

Best regards,
Hervé