hwmon: (lm25066) Support SAMPLES_FOR_AVG register

Manufacturer specific SAMPLES_FOR_AVG register allows setting the number
of samples used in computing the average values (PMBUS_VIRT_READ_*_AVG).
The number we write is an exponent of base 2 of the number of samples so
for example writing 3 will result in 8 samples average.

Signed-off-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/pmbus/lm25066.c

@@ -26,6 +26,7 @@
 #include <linux/err.h>
 #include <linux/slab.h>
 #include <linux/i2c.h>
+#include <linux/log2.h>
 #include "pmbus.h"
 
 enum chips { lm25056, lm25066, lm5064, lm5066, lm5066i };
@@ -39,12 +40,15 @@ enum chips { lm25056, lm25066, lm5064, lm5066, lm5066i };
 #define LM25066_CLEAR_PIN_PEAK		0xd6
 #define LM25066_DEVICE_SETUP		0xd9
 #define LM25066_READ_AVG_VIN		0xdc
+#define LM25066_SAMPLES_FOR_AVG		0xdb
 #define LM25066_READ_AVG_VOUT		0xdd
 #define LM25066_READ_AVG_IIN		0xde
 #define LM25066_READ_AVG_PIN		0xdf
 
 #define LM25066_DEV_SETUP_CL		BIT(4)	/* Current limit */
 
+#define LM25066_SAMPLES_FOR_AVG_MAX	4096
+
 /* LM25056 only */
 
 #define LM25056_VAUX_OV_WARN_LIMIT	0xe3
@@ -284,6 +288,12 @@ static int lm25066_read_word_data(struct i2c_client *client, int page, int reg)
 	case PMBUS_VIRT_RESET_PIN_HISTORY:
 		ret = 0;
 		break;
+	case PMBUS_VIRT_SAMPLES:
+		ret = pmbus_read_byte_data(client, 0, LM25066_SAMPLES_FOR_AVG);
+		if (ret < 0)
+			break;
+		ret = 1 << ret;
+		break;
 	default:
 		ret = -ENODATA;
 		break;
@@ -398,6 +408,11 @@ static int lm25066_write_word_data(struct i2c_client *client, int page, int reg,
 	case PMBUS_VIRT_RESET_PIN_HISTORY:
 		ret = pmbus_write_byte(client, 0, LM25066_CLEAR_PIN_PEAK);
 		break;
+	case PMBUS_VIRT_SAMPLES:
+		word = clamp_val(word, 1, LM25066_SAMPLES_FOR_AVG_MAX);
+		ret = pmbus_write_byte_data(client, 0, LM25066_SAMPLES_FOR_AVG,
+					    ilog2(word));
+		break;
 	default:
 		ret = -ENODATA;
 		break;
@@ -438,7 +453,7 @@ static int lm25066_probe(struct i2c_client *client,
 
 	info->func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VMON
 	  | PMBUS_HAVE_PIN | PMBUS_HAVE_IIN | PMBUS_HAVE_STATUS_INPUT
-	  | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP;
+	  | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP | PMBUS_HAVE_SAMPLES;
 
 	if (data->id == lm25056) {
 		info->func[0] |= PMBUS_HAVE_STATUS_VMON;