hwmon: (pmbus/stpddc60) Add ST STPDDC60 pmbus driver

Add hardware monitoring support for ST STPDDC60 Unversal Digital
Multicell Controller.

Signed-off-by: Erik Rosen <erik.rosen@metormote.com>
Link: https://lore.kernel.org/r/20210218115249.28513-3-erik.rosen@metormote.com
[groeck: Fixed whitespace error in Makefile]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

3 files changed, 259 insertions, 0 deletions

diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
index ee8c27b3b83d..28658b9f09ff 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/drivers/hwmon/pmbus/Kconfig
@@ -256,6 +256,16 @@ config SENSORS_Q54SJ108A2
 	  This driver can also be built as a module. If so, the module will
 	  be called q54sj108a2.
 
+config SENSORS_STPDDC60
+	tristate "ST STPDDC60"
+	help
+	  If you say yes here you get hardware monitoring support for ST
+	  STPDDC60 Universal Digital Multicell Controller, as well as for
+	  Flex BMR481.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called stpddc60.
+
 config SENSORS_TPS40422
 	tristate "TI TPS40422"
 	help
diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
index 685a6bc2b15f..ed1266f6fb01 100644
--- a/drivers/hwmon/pmbus/Makefile
+++ b/drivers/hwmon/pmbus/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_SENSORS_MP2975)	+= mp2975.o
 obj-$(CONFIG_SENSORS_PM6764TR)	+= pm6764tr.o
 obj-$(CONFIG_SENSORS_PXE1610)	+= pxe1610.o
 obj-$(CONFIG_SENSORS_Q54SJ108A2)	+= q54sj108a2.o
+obj-$(CONFIG_SENSORS_STPDDC60)	+= stpddc60.o
 obj-$(CONFIG_SENSORS_TPS40422)	+= tps40422.o
 obj-$(CONFIG_SENSORS_TPS53679)	+= tps53679.o
 obj-$(CONFIG_SENSORS_UCD9000)	+= ucd9000.o
diff --git a/drivers/hwmon/pmbus/stpddc60.c b/drivers/hwmon/pmbus/stpddc60.c
new file mode 100644
index 000000000000..3e6709542b63
--- /dev/null
+++ b/drivers/hwmon/pmbus/stpddc60.c
@@ -0,0 +1,248 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Hardware monitoring driver for the STPDDC60 controller
+ *
+ * Copyright (c) 2021 Flextronics International Sweden AB.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/pmbus.h>
+#include "pmbus.h"
+
+#define STPDDC60_MFR_READ_VOUT		0xd2
+#define STPDDC60_MFR_OV_LIMIT_OFFSET	0xe5
+#define STPDDC60_MFR_UV_LIMIT_OFFSET	0xe6
+
+static const struct i2c_device_id stpddc60_id[] = {
+	{"stpddc60", 0},
+	{"bmr481", 0},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, stpddc60_id);
+
+static struct pmbus_driver_info stpddc60_info = {
+	.pages = 1,
+	.func[0] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT
+		| PMBUS_HAVE_VIN | PMBUS_HAVE_STATUS_INPUT
+		| PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP
+		| PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT
+		| PMBUS_HAVE_POUT,
+};
+
+/*
+ * Calculate the closest absolute offset between commanded vout value
+ * and limit value in steps of 50mv in the range 0 (50mv) to 7 (400mv).
+ * Return 0 if the upper limit is lower than vout or if the lower limit
+ * is higher than vout.
+ */
+static u8 stpddc60_get_offset(int vout, u16 limit, bool over)
+{
+	int offset;
+	long v, l;
+
+	v = 250 + (vout - 1) * 5; /* Convert VID to mv */
+	l = (limit * 1000L) >> 8; /* Convert LINEAR to mv */
+
+	if (over == (l < v))
+		return 0;
+
+	offset = DIV_ROUND_CLOSEST(abs(l - v), 50);
+
+	if (offset > 0)
+		offset--;
+
+	return clamp_val(offset, 0, 7);
+}
+
+/*
+ * Adjust the linear format word to use the given fixed exponent.
+ */
+static u16 stpddc60_adjust_linear(u16 word, s16 fixed)
+{
+	s16 e, m, d;
+
+	e = ((s16)word) >> 11;
+	m = ((s16)((word & 0x7ff) << 5)) >> 5;
+	d = e - fixed;
+
+	if (d >= 0)
+		m <<= d;
+	else
+		m >>= -d;
+
+	return clamp_val(m, 0, 0x3ff) | ((fixed << 11) & 0xf800);
+}
+
+/*
+ * The VOUT_COMMAND register uses the VID format but the vout alarm limit
+ * registers use the LINEAR format so we override VOUT_MODE here to force
+ * LINEAR format for all registers.
+ */
+static int stpddc60_read_byte_data(struct i2c_client *client, int page, int reg)
+{
+	int ret;
+
+	if (page > 0)
+		return -ENXIO;
+
+	switch (reg) {
+	case PMBUS_VOUT_MODE:
+		ret = 0x18;
+		break;
+	default:
+		ret = -ENODATA;
+		break;
+	}
+
+	return ret;
+}
+
+/*
+ * The vout related registers return values in LINEAR11 format when LINEAR16
+ * is expected. Clear the top 5 bits to set the exponent part to zero to
+ * convert the value to LINEAR16 format.
+ */
+static int stpddc60_read_word_data(struct i2c_client *client, int page,
+				   int phase, int reg)
+{
+	int ret;
+
+	if (page > 0)
+		return -ENXIO;
+
+	switch (reg) {
+	case PMBUS_READ_VOUT:
+		ret = pmbus_read_word_data(client, page, phase,
+					   STPDDC60_MFR_READ_VOUT);
+		if (ret < 0)
+			return ret;
+		ret &= 0x7ff;
+		break;
+	case PMBUS_VOUT_OV_FAULT_LIMIT:
+	case PMBUS_VOUT_UV_FAULT_LIMIT:
+		ret = pmbus_read_word_data(client, page, phase, reg);
+		if (ret < 0)
+			return ret;
+		ret &= 0x7ff;
+		break;
+	default:
+		ret = -ENODATA;
+		break;
+	}
+
+	return ret;
+}
+
+/*
+ * The vout under- and over-voltage limits are set as an offset relative to
+ * the commanded vout voltage. The vin, iout, pout and temp limits must use
+ * the same fixed exponent the chip uses to encode the data when read.
+ */
+static int stpddc60_write_word_data(struct i2c_client *client, int page,
+				    int reg, u16 word)
+{
+	int ret;
+	u8 offset;
+
+	if (page > 0)
+		return -ENXIO;
+
+	switch (reg) {
+	case PMBUS_VOUT_OV_FAULT_LIMIT:
+		ret = pmbus_read_word_data(client, page, 0xff,
+					   PMBUS_VOUT_COMMAND);
+		if (ret < 0)
+			return ret;
+		offset = stpddc60_get_offset(ret, word, true);
+		ret = pmbus_write_byte_data(client, page,
+					    STPDDC60_MFR_OV_LIMIT_OFFSET,
+					    offset);
+		break;
+	case PMBUS_VOUT_UV_FAULT_LIMIT:
+		ret = pmbus_read_word_data(client, page, 0xff,
+					   PMBUS_VOUT_COMMAND);
+		if (ret < 0)
+			return ret;
+		offset = stpddc60_get_offset(ret, word, false);
+		ret = pmbus_write_byte_data(client, page,
+					    STPDDC60_MFR_UV_LIMIT_OFFSET,
+					    offset);
+		break;
+	case PMBUS_VIN_OV_FAULT_LIMIT:
+	case PMBUS_VIN_UV_FAULT_LIMIT:
+	case PMBUS_OT_FAULT_LIMIT:
+	case PMBUS_OT_WARN_LIMIT:
+	case PMBUS_IOUT_OC_FAULT_LIMIT:
+	case PMBUS_IOUT_OC_WARN_LIMIT:
+	case PMBUS_POUT_OP_FAULT_LIMIT:
+		ret = pmbus_read_word_data(client, page, 0xff, reg);
+		if (ret < 0)
+			return ret;
+		word = stpddc60_adjust_linear(word, ret >> 11);
+		ret = pmbus_write_word_data(client, page, reg, word);
+		break;
+	default:
+		ret = -ENODATA;
+		break;
+	}
+
+	return ret;
+}
+
+static int stpddc60_probe(struct i2c_client *client)
+{
+	int status;
+	u8 device_id[I2C_SMBUS_BLOCK_MAX + 1];
+	const struct i2c_device_id *mid;
+	struct pmbus_driver_info *info = &stpddc60_info;
+
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_READ_BYTE_DATA
+				     | I2C_FUNC_SMBUS_BLOCK_DATA))
+		return -ENODEV;
+
+	status = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, device_id);
+	if (status < 0) {
+		dev_err(&client->dev, "Failed to read Manufacturer Model\n");
+		return status;
+	}
+	for (mid = stpddc60_id; mid->name[0]; mid++) {
+		if (!strncasecmp(mid->name, device_id, strlen(mid->name)))
+			break;
+	}
+	if (!mid->name[0]) {
+		dev_err(&client->dev, "Unsupported device\n");
+		return -ENODEV;
+	}
+
+	info->read_byte_data = stpddc60_read_byte_data;
+	info->read_word_data = stpddc60_read_word_data;
+	info->write_word_data = stpddc60_write_word_data;
+
+	status = pmbus_do_probe(client, info);
+	if (status < 0)
+		return status;
+
+	pmbus_set_update(client, PMBUS_VOUT_OV_FAULT_LIMIT, true);
+	pmbus_set_update(client, PMBUS_VOUT_UV_FAULT_LIMIT, true);
+
+	return 0;
+}
+
+static struct i2c_driver stpddc60_driver = {
+	.driver = {
+		   .name = "stpddc60",
+		   },
+	.probe_new = stpddc60_probe,
+	.id_table = stpddc60_id,
+};
+
+module_i2c_driver(stpddc60_driver);
+
+MODULE_AUTHOR("Erik Rosen <erik.rosen@metormote.com>");
+MODULE_DESCRIPTION("PMBus driver for ST STPDDC60");
+MODULE_LICENSE("GPL");