sfc: Add hwmon driver for boards using SFC9000-family controllers

The SFC9000-family controllers have firmware to manage all board
peripherals including temperature, heat sink continuity and voltage
sensors.  The firmware reports sensor alarms, which we log, and
will shut down the board if necessary.

Some users may want to monitor their boards more closely, so add an
hwmon driver that exposes all sensors reported by the firmware.  Move
efx_mcdi_sensor_event() into the new file so it can share the array of
sensor labels with the hwmon driver.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

7 files changed, 471 insertions, 44 deletions

diff --git a/drivers/net/ethernet/sfc/Kconfig b/drivers/net/ethernet/sfc/Kconfig
index 5d18841f0f3..ae40b666739 100644
--- a/drivers/net/ethernet/sfc/Kconfig
+++ b/drivers/net/ethernet/sfc/Kconfig
@@ -19,3 +19,10 @@ config SFC_MTD
 	  This exposes the on-board flash memory as MTD devices (e.g.
 	  /dev/mtd1).  This makes it possible to upload new firmware
 	  to the NIC.
+config SFC_MCDI_MON
+	bool "Solarflare SFC9000-family hwmon support"
+	depends on SFC && HWMON && !(SFC=y && HWMON=m)
+	default y
+	----help---
+	  This exposes the on-board firmware-managed sensors as a
+	  hardware monitor device.
diff --git a/drivers/net/ethernet/sfc/Makefile b/drivers/net/ethernet/sfc/Makefile
index ab31c7124db..3fa2e25ccc4 100644
--- a/drivers/net/ethernet/sfc/Makefile
+++ b/drivers/net/ethernet/sfc/Makefile
@@ -2,7 +2,7 @@ sfc-y			+= efx.o nic.o falcon.o siena.o tx.o rx.o filter.o \
 			   falcon_xmac.o mcdi_mac.o \
 			   selftest.o ethtool.o qt202x_phy.o mdio_10g.o \
 			   tenxpress.o txc43128_phy.o falcon_boards.o \
-			   mcdi.o mcdi_phy.o
+			   mcdi.o mcdi_phy.o mcdi_mon.o
 sfc-$(CONFIG_SFC_MTD)	+= mtd.o
 
 obj-$(CONFIG_SFC)	+= sfc.o
diff --git a/drivers/net/ethernet/sfc/mcdi.c b/drivers/net/ethernet/sfc/mcdi.c
index f1cad22b30f..619f63a66ce 100644
--- a/drivers/net/ethernet/sfc/mcdi.c
+++ b/drivers/net/ethernet/sfc/mcdi.c
@@ -517,49 +517,6 @@ static void efx_mcdi_process_link_change(struct efx_nic *efx, efx_qword_t *ev)
 	efx_link_status_changed(efx);
 }
 
-static const char *const sensor_names[] = {
-	[MC_CMD_SENSOR_CONTROLLER_TEMP] = "Controller temp. sensor",
-	[MC_CMD_SENSOR_PHY_COMMON_TEMP] = "PHY shared temp. sensor",
-	[MC_CMD_SENSOR_CONTROLLER_COOLING] = "Controller cooling",
-	[MC_CMD_SENSOR_PHY0_TEMP] = "PHY 0 temp. sensor",
-	[MC_CMD_SENSOR_PHY0_COOLING] = "PHY 0 cooling",
-	[MC_CMD_SENSOR_PHY1_TEMP] = "PHY 1 temp. sensor",
-	[MC_CMD_SENSOR_PHY1_COOLING] = "PHY 1 cooling",
-	[MC_CMD_SENSOR_IN_1V0] = "1.0V supply sensor",
-	[MC_CMD_SENSOR_IN_1V2] = "1.2V supply sensor",
-	[MC_CMD_SENSOR_IN_1V8] = "1.8V supply sensor",
-	[MC_CMD_SENSOR_IN_2V5] = "2.5V supply sensor",
-	[MC_CMD_SENSOR_IN_3V3] = "3.3V supply sensor",
-	[MC_CMD_SENSOR_IN_12V0] = "12V supply sensor"
-};
-
-static const char *const sensor_status_names[] = {
-	[MC_CMD_SENSOR_STATE_OK] = "OK",
-	[MC_CMD_SENSOR_STATE_WARNING] = "Warning",
-	[MC_CMD_SENSOR_STATE_FATAL] = "Fatal",
-	[MC_CMD_SENSOR_STATE_BROKEN] = "Device failure",
-};
-
-static void efx_mcdi_sensor_event(struct efx_nic *efx, efx_qword_t *ev)
-{
-	unsigned int monitor, state, value;
-	const char *name, *state_txt;
-	monitor = EFX_QWORD_FIELD(*ev, MCDI_EVENT_SENSOREVT_MONITOR);
-	state = EFX_QWORD_FIELD(*ev, MCDI_EVENT_SENSOREVT_STATE);
-	value = EFX_QWORD_FIELD(*ev, MCDI_EVENT_SENSOREVT_VALUE);
-	/* Deal gracefully with the board having more drivers than we
-	 * know about, but do not expect new sensor states. */
-	name = (monitor >= ARRAY_SIZE(sensor_names))
-				    ? "No sensor name available" :
-				    sensor_names[monitor];
-	EFX_BUG_ON_PARANOID(state >= ARRAY_SIZE(sensor_status_names));
-	state_txt = sensor_status_names[state];
-
-	netif_err(efx, hw, efx->net_dev,
-		  "Sensor %d (%s) reports condition '%s' for raw value %d\n",
-		  monitor, name, state_txt, value);
-}
-
 /* Called from  falcon_process_eventq for MCDI events */
 void efx_mcdi_process_event(struct efx_channel *channel,
 			    efx_qword_t *event)
diff --git a/drivers/net/ethernet/sfc/mcdi.h b/drivers/net/ethernet/sfc/mcdi.h
index 4dd39fcca67..fbaa6efcd74 100644
--- a/drivers/net/ethernet/sfc/mcdi.h
+++ b/drivers/net/ethernet/sfc/mcdi.h
@@ -56,6 +56,15 @@ struct efx_mcdi_iface {
 	size_t resplen;
 };
 
+struct efx_mcdi_mon {
+	struct efx_buffer dma_buf;
+	struct mutex update_lock;
+	unsigned long last_update;
+	struct device *device;
+	struct efx_mcdi_mon_attribute *attrs;
+	unsigned int n_attrs;
+};
+
 extern void efx_mcdi_init(struct efx_nic *efx);
 
 extern int efx_mcdi_rpc(struct efx_nic *efx, unsigned cmd, const u8 *inbuf,
@@ -68,6 +77,7 @@ extern void efx_mcdi_mode_event(struct efx_nic *efx);
 
 extern void efx_mcdi_process_event(struct efx_channel *channel,
 				   efx_qword_t *event);
+extern void efx_mcdi_sensor_event(struct efx_nic *efx, efx_qword_t *ev);
 
 #define MCDI_PTR2(_buf, _ofst)						\
 	(((u8 *)_buf) + _ofst)
@@ -83,6 +93,10 @@ extern void efx_mcdi_process_event(struct efx_channel *channel,
 
 #define MCDI_PTR(_buf, _ofst)						\
 	MCDI_PTR2(_buf, MC_CMD_ ## _ofst ## _OFST)
+#define MCDI_ARRAY_PTR(_buf, _field, _type, _index)			\
+	MCDI_PTR2(_buf,							\
+		  MC_CMD_ ## _field ## _OFST +				\
+		  (_index) * MC_CMD_ ## _type ## _TYPEDEF_LEN)
 #define MCDI_SET_DWORD(_buf, _ofst, _value)				\
 	MCDI_SET_DWORD2(_buf, MC_CMD_ ## _ofst ## _OFST, _value)
 #define MCDI_DWORD(_buf, _ofst)						\
@@ -92,6 +106,12 @@ extern void efx_mcdi_process_event(struct efx_channel *channel,
 
 #define MCDI_EVENT_FIELD(_ev, _field)			\
 	EFX_QWORD_FIELD(_ev, MCDI_EVENT_ ## _field)
+#define MCDI_ARRAY_FIELD(_buf, _field1, _type, _index, _field2)		\
+	EFX_DWORD_FIELD(						\
+		*((efx_dword_t *)					\
+		  (MCDI_ARRAY_PTR(_buf, _field1, _type, _index) +	\
+		   (MC_CMD_ ## _type ## _TYPEDEF_ ## _field2 ## _OFST & ~3))), \
+		MC_CMD_ ## _type ## _TYPEDEF_ ## _field2)
 
 extern void efx_mcdi_print_fwver(struct efx_nic *efx, char *buf, size_t len);
 extern int efx_mcdi_drv_attach(struct efx_nic *efx, bool driver_operating,
@@ -131,4 +151,12 @@ extern int efx_mcdi_mac_stats(struct efx_nic *efx, dma_addr_t dma_addr,
 extern int efx_mcdi_mac_reconfigure(struct efx_nic *efx);
 extern bool efx_mcdi_mac_check_fault(struct efx_nic *efx);
 
+#ifdef CONFIG_SFC_MCDI_MON
+extern int efx_mcdi_mon_probe(struct efx_nic *efx);
+extern void efx_mcdi_mon_remove(struct efx_nic *efx);
+#else
+static inline int efx_mcdi_mon_probe(struct efx_nic *efx) { return 0; }
+static inline void efx_mcdi_mon_remove(struct efx_nic *efx) {}
+#endif
+
 #endif /* EFX_MCDI_H */
diff --git a/drivers/net/ethernet/sfc/mcdi_mon.c b/drivers/net/ethernet/sfc/mcdi_mon.c
new file mode 100644
index 00000000000..8a72c10b9a6
--- /dev/null
+++ b/drivers/net/ethernet/sfc/mcdi_mon.c
@@ -0,0 +1,415 @@
+/****************************************************************************
+ * Driver for Solarflare Solarstorm network controllers and boards
+ * Copyright 2011 Solarflare Communications Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation, incorporated herein by reference.
+ */
+
+#include <linux/bitops.h>
+#include <linux/slab.h>
+#include <linux/hwmon.h>
+#include <linux/stat.h>
+
+#include "net_driver.h"
+#include "mcdi.h"
+#include "mcdi_pcol.h"
+#include "nic.h"
+
+enum efx_hwmon_type {
+	EFX_HWMON_UNKNOWN,
+	EFX_HWMON_TEMP,         /* temperature */
+	EFX_HWMON_COOL,         /* cooling device, probably a heatsink */
+	EFX_HWMON_IN            /* input voltage */
+};
+
+static const struct {
+	const char *label;
+	enum efx_hwmon_type hwmon_type;
+	int port;
+} efx_mcdi_sensor_type[MC_CMD_SENSOR_ENTRY_MAXNUM] = {
+#define SENSOR(name, label, hwmon_type, port)			\
+	[MC_CMD_SENSOR_##name] = { label, hwmon_type, port }
+	SENSOR(CONTROLLER_TEMP,	   "Controller temp.",	   EFX_HWMON_TEMP, -1),
+	SENSOR(PHY_COMMON_TEMP,	   "PHY temp.",		   EFX_HWMON_TEMP, -1),
+	SENSOR(CONTROLLER_COOLING, "Controller cooling",   EFX_HWMON_COOL, -1),
+	SENSOR(PHY0_TEMP,	   "PHY temp.",		   EFX_HWMON_TEMP, 0),
+	SENSOR(PHY0_COOLING,	   "PHY cooling",	   EFX_HWMON_COOL, 0),
+	SENSOR(PHY1_TEMP,	   "PHY temp.",		   EFX_HWMON_TEMP, 1),
+	SENSOR(PHY1_COOLING, 	   "PHY cooling",	   EFX_HWMON_COOL, 1),
+	SENSOR(IN_1V0,		   "1.0V supply",	   EFX_HWMON_IN,   -1),
+	SENSOR(IN_1V2,		   "1.2V supply",	   EFX_HWMON_IN,   -1),
+	SENSOR(IN_1V8,		   "1.8V supply",	   EFX_HWMON_IN,   -1),
+	SENSOR(IN_2V5,		   "2.5V supply",	   EFX_HWMON_IN,   -1),
+	SENSOR(IN_3V3,		   "3.3V supply",	   EFX_HWMON_IN,   -1),
+	SENSOR(IN_12V0,		   "12.0V supply",	   EFX_HWMON_IN,   -1),
+	SENSOR(IN_1V2A,		   "1.2V analogue supply", EFX_HWMON_IN,   -1),
+	SENSOR(IN_VREF,		   "ref. voltage",	   EFX_HWMON_IN,   -1),
+#undef SENSOR
+};
+
+static const char *const sensor_status_names[] = {
+	[MC_CMD_SENSOR_STATE_OK] = "OK",
+	[MC_CMD_SENSOR_STATE_WARNING] = "Warning",
+	[MC_CMD_SENSOR_STATE_FATAL] = "Fatal",
+	[MC_CMD_SENSOR_STATE_BROKEN] = "Device failure",
+};
+
+void efx_mcdi_sensor_event(struct efx_nic *efx, efx_qword_t *ev)
+{
+	unsigned int type, state, value;
+	const char *name = NULL, *state_txt;
+
+	type = EFX_QWORD_FIELD(*ev, MCDI_EVENT_SENSOREVT_MONITOR);
+	state = EFX_QWORD_FIELD(*ev, MCDI_EVENT_SENSOREVT_STATE);
+	value = EFX_QWORD_FIELD(*ev, MCDI_EVENT_SENSOREVT_VALUE);
+
+	/* Deal gracefully with the board having more drivers than we
+	 * know about, but do not expect new sensor states. */
+	if (type < ARRAY_SIZE(efx_mcdi_sensor_type))
+		name = efx_mcdi_sensor_type[type].label;
+	if (!name)
+		name = "No sensor name available";
+	EFX_BUG_ON_PARANOID(state >= ARRAY_SIZE(sensor_status_names));
+	state_txt = sensor_status_names[state];
+
+	netif_err(efx, hw, efx->net_dev,
+		  "Sensor %d (%s) reports condition '%s' for raw value %d\n",
+		  type, name, state_txt, value);
+}
+
+#ifdef CONFIG_SFC_MCDI_MON
+
+struct efx_mcdi_mon_attribute {
+	struct device_attribute dev_attr;
+	unsigned int index;
+	unsigned int type;
+	unsigned int limit_value;
+	char name[12];
+};
+
+static int efx_mcdi_mon_update(struct efx_nic *efx)
+{
+	struct efx_mcdi_mon *hwmon = efx_mcdi_mon(efx);
+	u8 inbuf[MC_CMD_READ_SENSORS_IN_LEN];
+	int rc;
+
+	MCDI_SET_DWORD(inbuf, READ_SENSORS_IN_DMA_ADDR_LO,
+		       hwmon->dma_buf.dma_addr & 0xffffffff);
+	MCDI_SET_DWORD(inbuf, READ_SENSORS_IN_DMA_ADDR_HI,
+		       (u64)hwmon->dma_buf.dma_addr >> 32);
+
+	rc = efx_mcdi_rpc(efx, MC_CMD_READ_SENSORS,
+			  inbuf, sizeof(inbuf), NULL, 0, NULL);
+	if (rc == 0)
+		hwmon->last_update = jiffies;
+	return rc;
+}
+
+static ssize_t efx_mcdi_mon_show_name(struct device *dev,
+				      struct device_attribute *attr,
+				      char *buf)
+{
+	return sprintf(buf, "%s\n", KBUILD_MODNAME);
+}
+
+static int efx_mcdi_mon_get_entry(struct device *dev, unsigned int index,
+				  efx_dword_t *entry)
+{
+	struct efx_nic *efx = dev_get_drvdata(dev);
+	struct efx_mcdi_mon *hwmon = efx_mcdi_mon(efx);
+	int rc;
+
+	BUILD_BUG_ON(MC_CMD_READ_SENSORS_OUT_LEN != 0);
+
+	mutex_lock(&hwmon->update_lock);
+
+	/* Use cached value if last update was < 1 s ago */
+	if (time_before(jiffies, hwmon->last_update + HZ))
+		rc = 0;
+	else
+		rc = efx_mcdi_mon_update(efx);
+
+	/* Copy out the requested entry */
+	*entry = ((efx_dword_t *)hwmon->dma_buf.addr)[index];
+
+	mutex_unlock(&hwmon->update_lock);
+
+	return rc;
+}
+
+static ssize_t efx_mcdi_mon_show_value(struct device *dev,
+				       struct device_attribute *attr,
+				       char *buf)
+{
+	struct efx_mcdi_mon_attribute *mon_attr =
+		container_of(attr, struct efx_mcdi_mon_attribute, dev_attr);
+	efx_dword_t entry;
+	unsigned int value;
+	int rc;
+
+	rc = efx_mcdi_mon_get_entry(dev, mon_attr->index, &entry);
+	if (rc)
+		return rc;
+
+	value = EFX_DWORD_FIELD(entry, MC_CMD_SENSOR_VALUE_ENTRY_TYPEDEF_VALUE);
+
+	/* Convert temperature from degrees to milli-degrees Celsius */
+	if (efx_mcdi_sensor_type[mon_attr->type].hwmon_type == EFX_HWMON_TEMP)
+		value *= 1000;
+
+	return sprintf(buf, "%u\n", value);
+}
+
+static ssize_t efx_mcdi_mon_show_limit(struct device *dev,
+				       struct device_attribute *attr,
+				       char *buf)
+{
+	struct efx_mcdi_mon_attribute *mon_attr =
+		container_of(attr, struct efx_mcdi_mon_attribute, dev_attr);
+	unsigned int value;
+
+	value = mon_attr->limit_value;
+
+	/* Convert temperature from degrees to milli-degrees Celsius */
+	if (efx_mcdi_sensor_type[mon_attr->type].hwmon_type == EFX_HWMON_TEMP)
+		value *= 1000;
+
+	return sprintf(buf, "%u\n", value);
+}
+
+static ssize_t efx_mcdi_mon_show_alarm(struct device *dev,
+				       struct device_attribute *attr,
+				       char *buf)
+{
+	struct efx_mcdi_mon_attribute *mon_attr =
+		container_of(attr, struct efx_mcdi_mon_attribute, dev_attr);
+	efx_dword_t entry;
+	int state;
+	int rc;
+
+	rc = efx_mcdi_mon_get_entry(dev, mon_attr->index, &entry);
+	if (rc)
+		return rc;
+
+	state = EFX_DWORD_FIELD(entry, MC_CMD_SENSOR_VALUE_ENTRY_TYPEDEF_STATE);
+	return sprintf(buf, "%d\n", state != MC_CMD_SENSOR_STATE_OK);
+}
+
+static ssize_t efx_mcdi_mon_show_label(struct device *dev,
+				       struct device_attribute *attr,
+				       char *buf)
+{
+	struct efx_mcdi_mon_attribute *mon_attr =
+		container_of(attr, struct efx_mcdi_mon_attribute, dev_attr);
+	return sprintf(buf, "%s\n",
+		       efx_mcdi_sensor_type[mon_attr->type].label);
+}
+
+static int
+efx_mcdi_mon_add_attr(struct efx_nic *efx, const char *name,
+		      ssize_t (*reader)(struct device *,
+					struct device_attribute *, char *),
+		      unsigned int index, unsigned int type,
+		      unsigned int limit_value)
+{
+	struct efx_mcdi_mon *hwmon = efx_mcdi_mon(efx);
+	struct efx_mcdi_mon_attribute *attr = &hwmon->attrs[hwmon->n_attrs];
+	int rc;
+
+	strlcpy(attr->name, name, sizeof(attr->name));
+	attr->index = index;
+	attr->type = type;
+	attr->limit_value = limit_value;
+	attr->dev_attr.attr.name = attr->name;
+	attr->dev_attr.attr.mode = S_IRUGO;
+	attr->dev_attr.show = reader;
+	rc = device_create_file(&efx->pci_dev->dev, &attr->dev_attr);
+	if (rc == 0)
+		++hwmon->n_attrs;
+	return rc;
+}
+
+int efx_mcdi_mon_probe(struct efx_nic *efx)
+{
+	struct efx_mcdi_mon *hwmon = efx_mcdi_mon(efx);
+	unsigned int n_attrs, n_temp = 0, n_cool = 0, n_in = 0;
+	u8 outbuf[MC_CMD_SENSOR_INFO_OUT_LENMAX];
+	size_t outlen;
+	char name[12];
+	u32 mask;
+	int rc, i, type;
+
+	BUILD_BUG_ON(MC_CMD_SENSOR_INFO_IN_LEN != 0);
+
+	rc = efx_mcdi_rpc(efx, MC_CMD_SENSOR_INFO, NULL, 0,
+			  outbuf, sizeof(outbuf), &outlen);
+	if (rc)
+		return rc;
+	if (outlen < MC_CMD_SENSOR_INFO_OUT_LENMIN)
+		return -EIO;
+
+	/* Find out which sensors are present.  Don't create a device
+	 * if there are none.
+	 */
+	mask = MCDI_DWORD(outbuf, SENSOR_INFO_OUT_MASK);
+	if (mask == 0)
+		return 0;
+
+	/* Check again for short response */
+	if (outlen < MC_CMD_SENSOR_INFO_OUT_LEN(hweight32(mask)))
+		return -EIO;
+
+	rc = efx_nic_alloc_buffer(efx, &hwmon->dma_buf,
+				  4 * MC_CMD_SENSOR_ENTRY_MAXNUM);
+	if (rc)
+		return rc;
+
+	mutex_init(&hwmon->update_lock);
+	efx_mcdi_mon_update(efx);
+
+	/* Allocate space for the maximum possible number of
+	 * attributes for this set of sensors: name of the driver plus
+	 * value, min, max, crit, alarm and label for each sensor.
+	 */
+	n_attrs = 1 + 6 * hweight32(mask);
+	hwmon->attrs = kcalloc(n_attrs, sizeof(*hwmon->attrs), GFP_KERNEL);
+	if (!hwmon->attrs) {
+		rc = -ENOMEM;
+		goto fail;
+	}
+
+	hwmon->device = hwmon_device_register(&efx->pci_dev->dev);
+	if (IS_ERR(hwmon->device)) {
+		rc = PTR_ERR(hwmon->device);
+		goto fail;
+	}
+
+	rc = efx_mcdi_mon_add_attr(efx, "name", efx_mcdi_mon_show_name, 0, 0, 0);
+	if (rc)
+		goto fail;
+
+	for (i = 0, type = -1; ; i++) {
+		const char *hwmon_prefix;
+		unsigned hwmon_index;
+		u16 min1, max1, min2, max2;
+
+		/* Find next sensor type or exit if there is none */
+		type++;
+		while (!(mask & (1 << type))) {
+			type++;
+			if (type == 32)
+				return 0;
+		}
+
+		/* Skip sensors specific to a different port */
+		if (efx_mcdi_sensor_type[type].hwmon_type != EFX_HWMON_UNKNOWN &&
+		    efx_mcdi_sensor_type[type].port >= 0 &&
+		    efx_mcdi_sensor_type[type].port != efx_port_num(efx))
+			continue;
+
+		switch (efx_mcdi_sensor_type[type].hwmon_type) {
+		case EFX_HWMON_TEMP:
+			hwmon_prefix = "temp";
+			hwmon_index = ++n_temp; /* 1-based */
+			break;
+		case EFX_HWMON_COOL:
+			/* This is likely to be a heatsink, but there
+			 * is no convention for representing cooling
+			 * devices other than fans.
+			 */
+			hwmon_prefix = "fan";
+			hwmon_index = ++n_cool; /* 1-based */
+			break;
+		default:
+			hwmon_prefix = "in";
+			hwmon_index = n_in++; /* 0-based */
+			break;
+		}
+
+		min1 = MCDI_ARRAY_FIELD(outbuf, SENSOR_ENTRY,
+					SENSOR_INFO_ENTRY, i, MIN1);
+		max1 = MCDI_ARRAY_FIELD(outbuf, SENSOR_ENTRY,
+					SENSOR_INFO_ENTRY, i, MAX1);
+		min2 = MCDI_ARRAY_FIELD(outbuf, SENSOR_ENTRY,
+					SENSOR_INFO_ENTRY, i, MIN2);
+		max2 = MCDI_ARRAY_FIELD(outbuf, SENSOR_ENTRY,
+					SENSOR_INFO_ENTRY, i, MAX2);
+
+		if (min1 != max1) {
+			snprintf(name, sizeof(name), "%s%u_input",
+				 hwmon_prefix, hwmon_index);
+			rc = efx_mcdi_mon_add_attr(
+				efx, name, efx_mcdi_mon_show_value, i, type, 0);
+			if (rc)
+				goto fail;
+
+			snprintf(name, sizeof(name), "%s%u_min",
+				 hwmon_prefix, hwmon_index);
+			rc = efx_mcdi_mon_add_attr(
+				efx, name, efx_mcdi_mon_show_limit,
+				i, type, min1);
+			if (rc)
+				goto fail;
+
+			snprintf(name, sizeof(name), "%s%u_max",
+				 hwmon_prefix, hwmon_index);
+			rc = efx_mcdi_mon_add_attr(
+				efx, name, efx_mcdi_mon_show_limit,
+				i, type, max1);
+			if (rc)
+				goto fail;
+
+			if (min2 != max2) {
+				/* Assume max2 is critical value.
+				 * But we have no good way to expose min2.
+				 */
+				snprintf(name, sizeof(name), "%s%u_crit",
+					 hwmon_prefix, hwmon_index);
+				rc = efx_mcdi_mon_add_attr(
+					efx, name, efx_mcdi_mon_show_limit,
+					i, type, max2);
+				if (rc)
+					goto fail;
+			}
+		}
+
+		snprintf(name, sizeof(name), "%s%u_alarm",
+			 hwmon_prefix, hwmon_index);
+		rc = efx_mcdi_mon_add_attr(
+			efx, name, efx_mcdi_mon_show_alarm, i, type, 0);
+		if (rc)
+			goto fail;
+
+		if (efx_mcdi_sensor_type[type].label) {
+			snprintf(name, sizeof(name), "%s%u_label",
+				 hwmon_prefix, hwmon_index);
+			rc = efx_mcdi_mon_add_attr(
+				efx, name, efx_mcdi_mon_show_label, i, type, 0);
+			if (rc)
+				goto fail;
+		}
+	}
+
+fail:
+	efx_mcdi_mon_remove(efx);
+	return rc;
+}
+
+void efx_mcdi_mon_remove(struct efx_nic *efx)
+{
+	struct siena_nic_data *nic_data = efx->nic_data;
+	struct efx_mcdi_mon *hwmon = &nic_data->hwmon;
+	unsigned int i;
+
+	for (i = 0; i < hwmon->n_attrs; i++)
+		device_remove_file(&efx->pci_dev->dev,
+				   &hwmon->attrs[i].dev_attr);
+	kfree(hwmon->attrs);
+	if (hwmon->device)
+		hwmon_device_unregister(hwmon->device);
+	efx_nic_free_buffer(efx, &hwmon->dma_buf);
+}
+
+#endif /* CONFIG_SFC_MCDI_MON */
diff --git a/drivers/net/ethernet/sfc/nic.h b/drivers/net/ethernet/sfc/nic.h
index a3ccd0b9d78..905a1877d60 100644
--- a/drivers/net/ethernet/sfc/nic.h
+++ b/drivers/net/ethernet/sfc/nic.h
@@ -144,12 +144,26 @@ static inline struct falcon_board *falcon_board(struct efx_nic *efx)
  * struct siena_nic_data - Siena NIC state
  * @mcdi: Management-Controller-to-Driver Interface
  * @wol_filter_id: Wake-on-LAN packet filter id
+ * @hwmon: Hardware monitor state
  */
 struct siena_nic_data {
 	struct efx_mcdi_iface mcdi;
 	int wol_filter_id;
+#ifdef CONFIG_SFC_MCDI_MON
+	struct efx_mcdi_mon hwmon;
+#endif
 };
 
+#ifdef CONFIG_SFC_MCDI_MON
+static inline struct efx_mcdi_mon *efx_mcdi_mon(struct efx_nic *efx)
+{
+	struct siena_nic_data *nic_data;
+	EFX_BUG_ON_PARANOID(efx_nic_rev(efx) < EFX_REV_SIENA_A0);
+	nic_data = efx->nic_data;
+	return &nic_data->hwmon;
+}
+#endif
+
 extern const struct efx_nic_type falcon_a1_nic_type;
 extern const struct efx_nic_type falcon_b0_nic_type;
 extern const struct efx_nic_type siena_a0_nic_type;
diff --git a/drivers/net/ethernet/sfc/siena.c b/drivers/net/ethernet/sfc/siena.c
index f05425842b3..d3c4169e2a0 100644
--- a/drivers/net/ethernet/sfc/siena.c
+++ b/drivers/net/ethernet/sfc/siena.c
@@ -300,6 +300,10 @@ static int siena_probe_nic(struct efx_nic *efx)
 		goto fail5;
 	}
 
+	rc = efx_mcdi_mon_probe(efx);
+	if (rc)
+		goto fail5;
+
 	return 0;
 
 fail5:
@@ -387,6 +391,8 @@ static int siena_init_nic(struct efx_nic *efx)
 
 static void siena_remove_nic(struct efx_nic *efx)
 {
+	efx_mcdi_mon_remove(efx);
+
 	efx_nic_free_buffer(efx, &efx->irq_status);
 
 	siena_reset_hw(efx, RESET_TYPE_ALL);