[PATCH v3 4/5] 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>

---
v3:
  - fix alphabetical order in multiple places
  - change PMBUS_READ_TEMPERATURE_1_SIGN macro name to
    MPM82504_READ_TEMPERATURE_1_SIGN
  - use sign_extend32()
  - fix typo in documentation
v2:
  - fixed signedess for temperatures < 0 deg C
  - removed empty lines
---
 Documentation/hwmon/mpq8785.rst | 20 +++++++++++++++-----
 drivers/hwmon/pmbus/mpq8785.c   | 33 ++++++++++++++++++++++++++++++++-
 2 files changed, 47 insertions(+), 6 deletions(-)

diff --git a/Documentation/hwmon/mpq8785.rst b/Documentation/hwmon/mpq8785.rst
index bf8176b87086..b91fefb1a84c 100644
--- a/Documentation/hwmon/mpq8785.rst
+++ b/Documentation/hwmon/mpq8785.rst
@@ -5,6 +5,7 @@ Kernel driver mpq8785
 
 Supported chips:
 
+  * MPS MPM82504
   * MPS MPQ8785
 
     Prefix: 'mpq8785'
@@ -14,6 +15,14 @@ Author: Charles Hsu <ythsu0511@gmail.com>
 Description
 -----------
 
+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 MPQ8785 is a fully integrated, PMBus-compatible, high-frequency, synchronous
 buck converter. The MPQ8785 offers a very compact solution that achieves up to
 40A output current per phase, with excellent load and line regulation over a
@@ -23,18 +32,19 @@ output current 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 channels 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 MPM82504 is available in a BGA (15mmx30mmx5.18mm)
+package and the MPQ8785 is available in a TLGA (5mmx6mm) package.
 
 Device compliant with:
 
diff --git a/drivers/hwmon/pmbus/mpq8785.c b/drivers/hwmon/pmbus/mpq8785.c
index 2e7c0d0c3f81..1e12e7267a7f 100644
--- a/drivers/hwmon/pmbus/mpq8785.c
+++ b/drivers/hwmon/pmbus/mpq8785.c
@@ -4,14 +4,19 @@
  */
 
 #include <linux/i2c.h>
+#include <linux/bitops.h>
 #include <linux/module.h>
 #include <linux/property.h>
 #include <linux/of_device.h>
 #include "pmbus.h"
 
-enum chips { mpq8785 };
+#define MPM82504_READ_TEMPERATURE_1_SIGN	BIT(9)
+#define MPM82504_READ_TEMPERATURE_1_SIGN_POS	9
+
+enum chips { mpm82504, mpq8785 };
 
 static u16 voltage_scale_loop_max_val[] = {
+	[mpm82504] = GENMASK(9, 0),
 	[mpq8785] = GENMASK(10, 0),
 };
 
@@ -41,6 +46,23 @@ 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 & MPM82504_READ_TEMPERATURE_1_SIGN)
+		ret = sign_extend32(ret, MPM82504_READ_TEMPERATURE_1_SIGN_POS) & 0xffff;
+
+	return ret;
+}
+
 static struct pmbus_driver_info mpq8785_info = {
 	.pages = 1,
 	.format[PSC_VOLTAGE_IN] = direct,
@@ -63,12 +85,14 @@ static struct pmbus_driver_info mpq8785_info = {
 };
 
 static const struct i2c_device_id mpq8785_id[] = {
+	{ "mpm82504", mpm82504 },
 	{ "mpq8785", mpq8785 },
 	{ },
 };
 MODULE_DEVICE_TABLE(i2c, mpq8785_id);
 
 static const struct of_device_id __maybe_unused mpq8785_of_match[] = {
+	{ .compatible = "mps,mpm82504", .data = (void *)mpm82504 },
 	{ .compatible = "mps,mpq8785", .data = (void *)mpq8785 },
 	{}
 };
@@ -92,6 +116,13 @@ static int mpq8785_probe(struct i2c_client *client)
 		chip_id = (kernel_ulong_t)i2c_get_match_data(client);
 
 	switch (chip_id) {
+	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;
 	case mpq8785:
 		info->identify = mpq8785_identify;
 		break;
-- 
2.43.0