hwmon: Add driver for fsp-3y PSUs and PDUs

After some testing, I have found out there is a timing issue with this
device. After setting page, the device doesn't immediately react and
gives values from the previous page for some time. This is why there
needs to be a delay between pmbus_set_page and the actual read.

Also, a lot of the standard commands don't work with the devices, so
they are filtered out in the custom read function.

Signed-off-by: Václav Kubernát <kubernat@cesnet.cz>

drivers/hwmon/pmbus/Kconfig

@@ -56,6 +56,15 @@ config SENSORS_BEL_PFE
 	  This driver can also be built as a module. If so, the module will
 	  be called bel-pfe.
 
+config SENSORS_FSP_3Y
+	tristate "FSP/3Y-Power power supplies"
+	help
+	  If you say yes here you get hardware monitoring support for
+	  FSP/3Y-Power hot-swap power supplies.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called fsp-3y.
+
 config SENSORS_IBM_CFFPS
 	tristate "IBM Common Form Factor Power Supply"
 	depends on LEDS_CLASS

drivers/hwmon/pmbus/Makefile

@@ -8,6 +8,7 @@ obj-$(CONFIG_SENSORS_PMBUS)	+= pmbus.o
 obj-$(CONFIG_SENSORS_ADM1266)	+= adm1266.o
 obj-$(CONFIG_SENSORS_ADM1275)	+= adm1275.o
 obj-$(CONFIG_SENSORS_BEL_PFE)	+= bel-pfe.o
+obj-$(CONFIG_SENSORS_FSP_3Y)	+= fsp-3y.o
 obj-$(CONFIG_SENSORS_IBM_CFFPS)	+= ibm-cffps.o
 obj-$(CONFIG_SENSORS_INSPUR_IPSPS) += inspur-ipsps.o
 obj-$(CONFIG_SENSORS_IR35221)	+= ir35221.o

drivers/hwmon/pmbus/fsp-3y.c

@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Hardware monitoring driver for FSP 3Y-Power PSUs
+ *
+ * Copyright (c) 2021 Václav Kubernát, CESNET
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include "pmbus.h"
+
+#define YM2151_PAGE_12V		0x00
+#define YM2151_PAGE_5V		0x20
+#define YH5151E_PAGE_12V	0x00
+#define YH5151E_PAGE_5V		0x10
+#define YH5151E_PAGE_3V3	0x11
+
+enum chips {
+	ym2151e,
+	yh5151e
+};
+
+static int set_page(struct i2c_client *client, int page)
+{
+	int rv;
+
+	rv = i2c_smbus_read_byte_data(client, PMBUS_PAGE);
+
+	if (rv < 0)
+		return rv;
+
+	if (rv != page) {
+		rv = pmbus_set_page(client, page, 0xff);
+		if (rv < 0)
+			return rv;
+
+		msleep(20);
+	}
+
+	return 0;
+}
+
+static int fsp3y_read_byte_data(struct i2c_client *client, int page, int reg)
+{
+	int rv;
+
+	rv = set_page(client, page);
+	if (rv < 0)
+		return rv;
+
+	return i2c_smbus_read_byte_data(client, reg);
+}
+
+static int fsp3y_read_word_data(struct i2c_client *client, int page, int phase, int reg)
+{
+	int rv;
+
+	if (reg >= PMBUS_VIRT_BASE)
+		return -ENXIO;
+
+	switch (reg) {
+	case PMBUS_OT_WARN_LIMIT:
+	case PMBUS_OT_FAULT_LIMIT:
+	case PMBUS_UT_WARN_LIMIT:
+	case PMBUS_UT_FAULT_LIMIT:
+	case PMBUS_VIN_UV_WARN_LIMIT:
+	case PMBUS_VIN_UV_FAULT_LIMIT:
+	case PMBUS_VIN_OV_FAULT_LIMIT:
+	case PMBUS_VIN_OV_WARN_LIMIT:
+	case PMBUS_IOUT_OC_WARN_LIMIT:
+	case PMBUS_IOUT_UC_FAULT_LIMIT:
+	case PMBUS_IOUT_OC_FAULT_LIMIT:
+	case PMBUS_IIN_OC_WARN_LIMIT:
+	case PMBUS_IIN_OC_FAULT_LIMIT:
+	case PMBUS_VOUT_UV_WARN_LIMIT:
+	case PMBUS_VOUT_UV_FAULT_LIMIT:
+	case PMBUS_VOUT_OV_WARN_LIMIT:
+	case PMBUS_VOUT_OV_FAULT_LIMIT:
+	case PMBUS_MFR_VIN_MIN:
+	case PMBUS_MFR_VIN_MAX:
+	case PMBUS_MFR_IIN_MAX:
+	case PMBUS_MFR_VOUT_MIN:
+	case PMBUS_MFR_VOUT_MAX:
+	case PMBUS_MFR_IOUT_MAX:
+	case PMBUS_MFR_PIN_MAX:
+	case PMBUS_POUT_MAX:
+	case PMBUS_POUT_OP_WARN_LIMIT:
+	case PMBUS_POUT_OP_FAULT_LIMIT:
+	case PMBUS_MFR_MAX_TEMP_1:
+	case PMBUS_MFR_MAX_TEMP_2:
+	case PMBUS_MFR_MAX_TEMP_3:
+	case PMBUS_MFR_POUT_MAX:
+		return -ENXIO;
+	}
+
+	rv = set_page(client, page);
+	if (rv < 0)
+		return rv;
+
+	return i2c_smbus_read_word_data(client, reg);
+}
+
+struct pmbus_driver_info fsp3y_info[] = {
+	[ym2151e] = {
+		.pages = 0x21,
+		.func[YM2151_PAGE_12V] =
+			PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
+			PMBUS_HAVE_PIN | PMBUS_HAVE_POUT  |
+			PMBUS_HAVE_TEMP | PMBUS_HAVE_TEMP2 |
+			PMBUS_HAVE_VIN | PMBUS_HAVE_IIN |
+			PMBUS_HAVE_FAN12,
+		.func[YM2151_PAGE_5V] =
+			PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT,
+			PMBUS_HAVE_IIN,
+		.read_word_data = fsp3y_read_word_data,
+		.read_byte_data = fsp3y_read_byte_data,
+	},
+	[yh5151e] = {
+		.pages = 0x12,
+		.func[YH5151E_PAGE_12V] =
+			PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
+			PMBUS_HAVE_POUT  |
+			PMBUS_HAVE_TEMP | PMBUS_HAVE_TEMP2 | PMBUS_HAVE_TEMP3,
+		.func[YH5151E_PAGE_5V] =
+			PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
+			PMBUS_HAVE_POUT,
+		.func[YH5151E_PAGE_3V3] =
+			PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
+			PMBUS_HAVE_POUT,
+		.read_word_data = fsp3y_read_word_data,
+		.read_byte_data = fsp3y_read_byte_data,
+	}
+};
+
+static int fsp3y_probe(struct i2c_client *client,
+		       const struct i2c_device_id *id)
+{
+	return pmbus_do_probe(client, &fsp3y_info[id->driver_data]);
+}
+
+static const struct i2c_device_id pmbus_id[] = {
+	{"fsp3y_ym2151e", ym2151e},
+	{"fsp3y_yh5151e", yh5151e},
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, pmbus_id);
+
+/* This is the driver that will be inserted */
+static struct i2c_driver fsp3y_driver = {
+	.driver = {
+		   .name = "fsp3y",
+		   },
+	.probe = fsp3y_probe,
+	.id_table = pmbus_id
+};
+
+module_i2c_driver(fsp3y_driver);
+
+MODULE_AUTHOR("Václav Kubernát");
+MODULE_DESCRIPTION("PMBus driver for FSP/3Y-Power power supplies");
+MODULE_LICENSE("GPL");