[PATCH v2 2/5] hwmon: pmbus: mpq8785: Add support for MPM82504

[Pawel Dembicki <paweldembicki@gmail.com>]

Add support for the Monolithic Power Systems MPM82504 digital voltage
regulator. MPM82504 uses PMBus direct format for voltage output.

Tested with device tree based matching.

Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>

---
v2:
  - fixed signedess for temperatures < 0 deg C
  - remove empty lines
---
 Documentation/hwmon/mpq8785.rst | 20 +++++++++++++++-----
 drivers/hwmon/pmbus/mpq8785.c   | 30 +++++++++++++++++++++++++++++-
 2 files changed, 44 insertions(+), 6 deletions(-)

diff --git a/Documentation/hwmon/mpq8785.rst b/Documentation/hwmon/mpq8785.rst
index bf8176b87086..be228ee58ce2 100644
--- a/Documentation/hwmon/mpq8785.rst
+++ b/Documentation/hwmon/mpq8785.rst
@@ -6,6 +6,7 @@ Kernel driver mpq8785
 Supported chips:
 
   * MPS MPQ8785
+  * MPS MPM82504
 
     Prefix: 'mpq8785'
 
@@ -20,21 +21,30 @@ buck converter. The MPQ8785 offers a very compact solution that achieves up to
 wide input supply range. The MPQ8785 operates at high efficiency over a wide
 output current load range.
 
+The MPM82504 is a quad 25A, scalable, fully integrated power module with a PMBus
+interface. The device offers a complete power solution that achieves up to 25A
+per output channel. The MPM82504 has four output channels that can be paralleled
+to provide 50A, 75A, or 100A of output current for flexible configurations.
+The device can also operate in parallel with the MPM3695-100 and additional
+MPM82504 devices to provide a higher output current. The MPM82504 operates
+at high efficiency across a wide load range.
+
 The PMBus interface provides converter configurations and key parameters
 monitoring.
 
-The MPQ8785 adopts MPS's proprietary multi-phase digital constant-on-time (MCOT)
+The devices adopts MPS's proprietary multi-phase digital constant-on-time (MCOT)
 control, which provides fast transient response and eases loop stabilization.
-The MCOT scheme also allows multiple MPQ8785 devices to be connected in parallel
-with excellent current sharing and phase interleaving for high-current
+The MCOT scheme also allows multiple devices or chennels to be connected in
+parallel with excellent current sharing and phase interleaving for high-current
 applications.
 
 Fully integrated protection features include over-current protection (OCP),
 over-voltage protection (OVP), under-voltage protection (UVP), and
 over-temperature protection (OTP).
 
-The MPQ8785 requires a minimal number of readily available, standard external
-components, and is available in a TLGA (5mmx6mm) package.
+All supported modules require a minimal number of readily available, standard
+external components. The MPQ8785 is available in a TLGA (5mmx6mm) package
+and the MPM82504 is available in a BGA (15mmx30mmx5.18mm) package.
 
 Device compliant with:
 
diff --git a/drivers/hwmon/pmbus/mpq8785.c b/drivers/hwmon/pmbus/mpq8785.c
index 00ec21b081cb..9a4a211b2aeb 100644
--- a/drivers/hwmon/pmbus/mpq8785.c
+++ b/drivers/hwmon/pmbus/mpq8785.c
@@ -8,7 +8,9 @@
 #include <linux/of_device.h>
 #include "pmbus.h"
 
-enum chips { mpq8785 };
+#define PMBUS_READ_TEMPERATURE_1_SIGN	BIT(9)
+
+enum chips { mpq8785, mpm82504 };
 
 static int mpq8785_identify(struct i2c_client *client,
 			    struct pmbus_driver_info *info)
@@ -36,6 +38,23 @@ static int mpq8785_identify(struct i2c_client *client,
 	return 0;
 };
 
+static int mpm82504_read_word_data(struct i2c_client *client, int page,
+				   int phase, int reg)
+{
+	int ret;
+
+	ret = pmbus_read_word_data(client, page, phase, reg);
+
+	if (ret < 0 || reg != PMBUS_READ_TEMPERATURE_1)
+		return ret;
+
+	/* Fix PMBUS_READ_TEMPERATURE_1 signedness */
+	if (ret & PMBUS_READ_TEMPERATURE_1_SIGN)
+		ret |= GENMASK(15, 10);
+
+	return ret;
+}
+
 static struct pmbus_driver_info mpq8785_info = {
 	.pages = 1,
 	.format[PSC_VOLTAGE_IN] = direct,
@@ -59,12 +78,14 @@ static struct pmbus_driver_info mpq8785_info = {
 
 static const struct i2c_device_id mpq8785_id[] = {
 	{ "mpq8785", mpq8785 },
+	{ "mpm82504", mpm82504 },
 	{ },
 };
 MODULE_DEVICE_TABLE(i2c, mpq8785_id);
 
 static const struct of_device_id __maybe_unused mpq8785_of_match[] = {
 	{ .compatible = "mps,mpq8785", .data = (void *)mpq8785 },
+	{ .compatible = "mps,mpm82504", .data = (void *)mpm82504 },
 	{}
 };
 MODULE_DEVICE_TABLE(of, mpq8785_of_match);
@@ -88,6 +109,13 @@ static int mpq8785_probe(struct i2c_client *client)
 	case mpq8785:
 		info->identify = mpq8785_identify;
 		break;
+	case mpm82504:
+		info->format[PSC_VOLTAGE_OUT] = direct;
+		info->m[PSC_VOLTAGE_OUT] = 8;
+		info->b[PSC_VOLTAGE_OUT] = 0;
+		info->R[PSC_VOLTAGE_OUT] = 2;
+		info->read_word_data = mpm82504_read_word_data;
+		break;
 	default:
 		return -ENODEV;
 	}
-- 
2.43.0