hwmon: (ltc2978) Add support for LTC3882

LTC3882 is mostly compatible with LTC3880. Major differences are that it
does not measure the input current, and it no longer supports LTC's legacy
mechanism to identify the chip.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/devicetree/bindings/hwmon/ltc2978.txt

@@ -6,6 +6,7 @@ Required properties:
   * "lltc,ltc2977"
   * "lltc,ltc2978"
   * "lltc,ltc3880"
+  * "lltc,ltc3882"
   * "lltc,ltc3883"
   * "lltc,ltm4676"
 - reg: I2C slave address
@@ -20,7 +21,7 @@ Valid names of regulators depend on number of supplies supported per device:
   * ltc2974 : vout0 - vout3
   * ltc2977 : vout0 - vout7
   * ltc2978 : vout0 - vout7
-  * ltc3880 : vout0 - vout1
+  * ltc3880, ltc3882 : vout0 - vout1
   * ltc3883 : vout0
   * ltm4676 : vout0 - vout1
 

Documentation/hwmon/ltc2978

@@ -19,6 +19,10 @@ Supported chips:
     Prefix: 'ltc3880'
     Addresses scanned: -
     Datasheet: http://www.linear.com/product/ltc3880
+  * Linear Technology LTC3882
+    Prefix: 'ltc3882'
+    Addresses scanned: -
+    Datasheet: http://www.linear.com/product/ltc3882
   * Linear Technology LTC3883
     Prefix: 'ltc3883'
     Addresses scanned: -
@@ -34,11 +38,12 @@ Author: Guenter Roeck <linux@roeck-us.net>
 Description
 -----------
 
-LTC2974 is a quad digital power supply manager. LTC2978 is an octal power supply
-monitor. LTC2977 is a pin compatible replacement for LTC2978. LTC3880 is a dual
-output poly-phase step-down DC/DC controller. LTC3883 is a single phase
-step-down DC/DC controller. LTM4676 is a dual 13A or single 26A uModule
-regulator.
+LTC2974 is a quad digital power supply managers.
+LTC2978 is an octal power supply monitor.
+LTC2977 is a pin compatible replacement for LTC2978.
+LTC3880 and LTC3882 are dual output poly-phase step-down DC/DC controllers.
+LTC3883 is a single phase step-down DC/DC controller.
+LTM4676 is a dual 13A or single 26A uModule regulator.
 
 
 Usage Notes
@@ -80,7 +85,7 @@ in[N]_label		"vout[1-8]".
 			LTC2974: N=2-5
 			LTC2977: N=2-9
 			LTC2978: N=2-9
-			LTC3880, LTM4676: N=2-3
+			LTC3880, LTC3882, LTM4676: N=2-3
 			LTC3883: N=2
 in[N]_input		Measured output voltage.
 in[N]_min		Minimum output voltage.
@@ -100,8 +105,9 @@ temp[N]_input		Measured temperature.
 			and temp5 reports the chip temperature.
 			On LTC2977 and LTC2978, only one temperature measurement
 			is supported and reports the chip temperature.
-			On LTC3880 and LTM4676, temp1 and temp2 report external
-			temperatures, and temp3 reports the chip temperature.
+			On LTC3880, LTC3882, and LTM4676, temp1 and temp2
+			report external temperatures, and temp3 reports
+			the chip temperature.
 			On LTC3883, temp1 reports an external temperature,
 			and temp2 reports the chip temperature.
 temp[N]_min		Mimimum temperature. LTC2974, LCT2977, and LTC2978 only.
@@ -128,7 +134,7 @@ power[N]_label		"pout[1-4]".
 			LTC2974: N=1-4
 			LTC2977: Not supported
 			LTC2978: Not supported
-			LTC3880, LTM4676: N=1-2
+			LTC3880, LTC3882, LTM4676: N=1-2
 			LTC3883: N=2
 power[N]_input		Measured output power.
 
@@ -143,7 +149,7 @@ curr[N]_label		"iout[1-4]".
 			LTC2974: N=1-4
 			LTC2977: not supported
 			LTC2978: not supported
-			LTC3880, LTM4676: N=2-3
+			LTC3880, LTC3882, LTM4676: N=2-3
 			LTC3883: N=2
 curr[N]_input		Measured output current.
 curr[N]_max		Maximum output current.

drivers/hwmon/pmbus/ltc2978.c

@@ -25,13 +25,13 @@
 #include <linux/regulator/driver.h>
 #include "pmbus.h"
 
-enum chips { ltc2974, ltc2977, ltc2978, ltc3880, ltc3883, ltm4676 };
+enum chips { ltc2974, ltc2977, ltc2978, ltc3880, ltc3882, ltc3883, ltm4676 };
 
 /* Common for all chips */
 #define LTC2978_MFR_VOUT_PEAK		0xdd
 #define LTC2978_MFR_VIN_PEAK		0xde
 #define LTC2978_MFR_TEMPERATURE_PEAK	0xdf
-#define LTC2978_MFR_SPECIAL_ID		0xe7
+#define LTC2978_MFR_SPECIAL_ID		0xe7	/* Not on LTC3882 */
 
 /* LTC2974, LCT2977, and LTC2978 */
 #define LTC2978_MFR_VOUT_MIN		0xfb
@@ -42,7 +42,7 @@ enum chips { ltc2974, ltc2977, ltc2978, ltc3880, ltc3883, ltm4676 };
 #define LTC2974_MFR_IOUT_PEAK		0xd7
 #define LTC2974_MFR_IOUT_MIN		0xd8
 
-/* LTC3880, LTC3883, and LTM4676 */
+/* LTC3880, LTC3882, LTC3883, and LTM4676 */
 #define LTC3880_MFR_IOUT_PEAK		0xd7
 #define LTC3880_MFR_CLEAR_PEAKS		0xe3
 #define LTC3880_MFR_TEMPERATURE2_PEAK	0xf4
@@ -313,7 +313,7 @@ static int ltc2978_clear_peaks(struct i2c_client *client, int page,
 {
 	int ret;
 
-	if (id == ltc3880 || id == ltc3883 || id == ltm4676)
+	if (id == ltc3880 || id == ltc3882 || id == ltc3883 || id == ltm4676)
 		ret = pmbus_write_byte(client, 0, LTC3880_MFR_CLEAR_PEAKS);
 	else
 		ret = pmbus_write_byte(client, page, PMBUS_CLEAR_FAULTS);
@@ -369,6 +369,7 @@ static const struct i2c_device_id ltc2978_id[] = {
 	{"ltc2977", ltc2977},
 	{"ltc2978", ltc2978},
 	{"ltc3880", ltc3880},
+	{"ltc3882", ltc3882},
 	{"ltc3883", ltc3883},
 	{"ltm4676", ltm4676},
 	{}
@@ -393,8 +394,30 @@ static int ltc2978_get_id(struct i2c_client *client)
 	int chip_id;
 
 	chip_id = i2c_smbus_read_word_data(client, LTC2978_MFR_SPECIAL_ID);
-	if (chip_id < 0)
-		return chip_id;
+	if (chip_id < 0) {
+		const struct i2c_device_id *id;
+		u8 buf[I2C_SMBUS_BLOCK_MAX];
+		int ret;
+
+		if (!i2c_check_functionality(client->adapter,
+					     I2C_FUNC_SMBUS_READ_BLOCK_DATA))
+			return -ENODEV;
+
+		ret = i2c_smbus_read_block_data(client, PMBUS_MFR_ID, buf);
+		if (ret < 0)
+			return ret;
+		if (ret < 3 || strncmp(buf, "LTC", 3))
+			return -ENODEV;
+
+		ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, buf);
+		if (ret < 0)
+			return ret;
+		for (id = &ltc2978_id[0]; strlen(id->name); id++) {
+			if (!strncasecmp(id->name, buf, strlen(id->name)))
+				return (int)id->driver_data;
+		}
+		return -ENODEV;
+	}
 
 	if (chip_id == LTC2974_ID_REV1 || chip_id == LTC2974_ID_REV2)
 		return ltc2974;
@@ -498,6 +521,20 @@ static int ltc2978_probe(struct i2c_client *client,
 		  | PMBUS_HAVE_POUT
 		  | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP;
 		break;
+	case ltc3882:
+		info->read_word_data = ltc3880_read_word_data;
+		info->pages = LTC3880_NUM_PAGES;
+		info->func[0] = PMBUS_HAVE_VIN
+		  | PMBUS_HAVE_STATUS_INPUT
+		  | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT
+		  | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT
+		  | PMBUS_HAVE_POUT | PMBUS_HAVE_TEMP
+		  | PMBUS_HAVE_TEMP2 | PMBUS_HAVE_STATUS_TEMP;
+		info->func[1] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT
+		  | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT
+		  | PMBUS_HAVE_POUT
+		  | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP;
+		break;
 	case ltc3883:
 		info->read_word_data = ltc3883_read_word_data;
 		info->pages = LTC3883_NUM_PAGES;
@@ -530,6 +567,7 @@ static const struct of_device_id ltc2978_of_match[] = {
 	{ .compatible = "lltc,ltc2977" },
 	{ .compatible = "lltc,ltc2978" },
 	{ .compatible = "lltc,ltc3880" },
+	{ .compatible = "lltc,ltc3882" },
 	{ .compatible = "lltc,ltc3883" },
 	{ .compatible = "lltc,ltm4676" },
 	{ }