[PATCH] hwmon: (pmbus) Let PMBus drivers report the supported PMBus revision

[PATCH] hwmon: (pmbus) Let PMBus drivers report the supported PMBus revision

[Guenter Roeck]

Some PMBus chips do not support the PMBUS_REVISION command. Knowing
the PMBUs revision supported by a chip is relevant for PMBUs core
functionality, so add support for letting chip drivers report the PMBUs
revision.

Use the new capability to report the PMBus revision supported by MAX20830.

While at it, add definitions for PMBUs revisons 1.3.1 and 1.4.

Cc: Nuno Sá <nuno.sa@analog.com>
Cc: Alexis Czezar Torreno <alexisczezar.torreno@analog.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/pmbus/max20830.c   |  2 ++
 drivers/hwmon/pmbus/pmbus.h      | 20 +++++++++++++----
 drivers/hwmon/pmbus/pmbus_core.c | 38 ++++++++++++++++++++++----------
 3 files changed, 44 insertions(+), 16 deletions(-)

diff --git a/drivers/hwmon/pmbus/max20830.c b/drivers/hwmon/pmbus/max20830.c
index e3470118fd36..d43ee6438b26 100644
--- a/drivers/hwmon/pmbus/max20830.c
+++ b/drivers/hwmon/pmbus/max20830.c
@@ -23,6 +23,8 @@ static struct pmbus_driver_info max20830_info = {
 		PMBUS_HAVE_TEMP |
 		PMBUS_HAVE_STATUS_VOUT | PMBUS_HAVE_STATUS_IOUT |
 		PMBUS_HAVE_STATUS_INPUT | PMBUS_HAVE_STATUS_TEMP,
+	.have_pmbus_revision = true,
+	.pmbus_revision = PMBUS_REV_13,
 };
 
 static int max20830_probe(struct i2c_client *client)
diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h
index 23e3eda58870..1af247de9075 100644
--- a/drivers/hwmon/pmbus/pmbus.h
+++ b/drivers/hwmon/pmbus/pmbus.h
@@ -420,10 +420,12 @@ enum pmbus_data_format { linear = 0, ieee754, direct, vid };
 enum vrm_version { vr11 = 0, vr12, vr13, imvp9, amd625mv, nvidia195mv };
 
 /* PMBus revision identifiers */
-#define PMBUS_REV_10 0x00	/* PMBus revision 1.0 */
-#define PMBUS_REV_11 0x11	/* PMBus revision 1.1 */
-#define PMBUS_REV_12 0x22	/* PMBus revision 1.2 */
-#define PMBUS_REV_13 0x33	/* PMBus revision 1.3 */
+#define PMBUS_REV_10	0x00	/* PMBus revision 1.0 */
+#define PMBUS_REV_11	0x11	/* PMBus revision 1.1 */
+#define PMBUS_REV_12	0x22	/* PMBus revision 1.2 */
+#define PMBUS_REV_13	0x33	/* PMBus revision 1.3 */
+#define PMBUS_REV_131	0x44	/* PMBus revision 1.3.1 */
+#define PMBUS_REV_14	0x55	/* PMBus revision 1.4 */
 
 /* Operation type flags for pmbus_update_ts */
 #define PMBUS_OP_WRITE		BIT(0)
@@ -488,6 +490,16 @@ struct pmbus_driver_info {
 	int access_delay;		/* in microseconds */
 	int write_delay;		/* in microseconds */
 	int page_change_delay;		/* in microseconds */
+
+	/*
+	 * Some chips do not support the PMBUS_REVISION command.
+	 * Drivers for such chips can report the supported PMBus revision here.
+	 *
+	 * Drivers must set have_pmbus_revision to true and provide the
+	 * supported PMBus version in pmbus_revision.
+	 */
+	bool have_pmbus_revision;	/* true if pmbus_revision is valid */
+	u8 pmbus_revision;		/* PMBus revision */
 };
 
 /* Regulator ops */
diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index 53501fa1a28e..3e13d09e2c1c 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -96,7 +96,8 @@ struct pmbus_data {
 
 	u32 flags;		/* from platform data */
 
-	u8 revision;	/* The PMBus revision the device is compliant with */
+	bool have_pmbus_revision;
+	u8 revision;		/* The PMBus revision the device is compliant with */
 
 	int exponent[PMBUS_PAGES];
 				/* linear mode: exponent for output voltages */
@@ -2847,9 +2848,16 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
 	if (!(data->flags & PMBUS_NO_WRITE_PROTECT))
 		pmbus_init_wp(client, data);
 
-	ret = i2c_smbus_read_byte_data(client, PMBUS_REVISION);
-	if (ret >= 0)
-		data->revision = ret;
+	if (info->have_pmbus_revision) {
+		data->have_pmbus_revision = true;
+		data->revision = info->pmbus_revision;
+	} else {
+		ret = i2c_smbus_read_byte_data(client, PMBUS_REVISION);
+		if (ret >= 0) {
+			data->have_pmbus_revision = true;
+			data->revision = ret;
+		}
+	}
 
 	if (data->info->pages)
 		pmbus_clear_faults(client);
@@ -3537,6 +3545,17 @@ static int pmbus_debugfs_get(void *data, u64 *val)
 DEFINE_DEBUGFS_ATTRIBUTE(pmbus_debugfs_ops, pmbus_debugfs_get, NULL,
 			 "0x%02llx\n");
 
+static int pmbus_debugfs_get_revision(void *data, u64 *val)
+{
+	struct pmbus_data *pdata = data;
+
+	*val = pdata->revision;
+
+	return 0;
+}
+DEFINE_DEBUGFS_ATTRIBUTE(pmbus_debugfs_revision_ops, pmbus_debugfs_get_revision, NULL,
+			 "0x%02llx\n");
+
 static int pmbus_debugfs_get_status(void *data, u64 *val)
 {
 	struct pmbus_debugfs_entry *entry = data;
@@ -3690,14 +3709,9 @@ static void pmbus_init_debugfs(struct i2c_client *client,
 				    &entries[idx++],
 				    &pmbus_debugfs_ops);
 	}
-	if (pmbus_check_byte_register(client, 0, PMBUS_REVISION)) {
-		entries[idx].client = client;
-		entries[idx].page = 0;
-		entries[idx].reg = PMBUS_REVISION;
-		debugfs_create_file("pmbus_revision", 0444, debugfs,
-				    &entries[idx++],
-				    &pmbus_debugfs_ops);
-	}
+	if (data->have_pmbus_revision)
+		debugfs_create_file("pmbus_revision", 0444, debugfs, data,
+				    &pmbus_debugfs_revision_ops);
 
 	for (i = 0; i < ARRAY_SIZE(pmbus_debugfs_block_data); i++) {
 		const struct pmbus_debugfs_data *d = &pmbus_debugfs_block_data[i];
-- 
2.45.2

Re: [PATCH] hwmon: (pmbus) Let PMBus drivers report the supported PMBus revision

[sashiko-bot]

> Some PMBus chips do not support the PMBUS_REVISION command. Knowing
> the PMBUs revision supported by a chip is relevant for PMBUs core
> functionality, so add support for letting chip drivers report the PMBUs
> revision.
> 
> Use the new capability to report the PMBus revision supported by MAX20830.
> 
> While at it, add definitions for PMBUs revisons 1.3.1 and 1.4.
> 
> Cc: Nuno Sá <nuno.sa@analog.com>
> Cc: Alexis Czezar Torreno <alexisczezar.torreno@analog.com>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260729011914.4018703-1-linux@roeck-us.net?part=1