Message-Id: <1489524906-19411-2-git-send-email-eajames@linux.vnet.ibm.com>
Date:   Tue, 14 Mar 2017 15:55:02 -0500
From:   Eddie James <eajames@...ux.vnet.ibm.com>
To:     linux@...ck-us.net
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hwmon@...r.kernel.org, linux-doc@...r.kernel.org,
        jdelvare@...e.com, corbet@....net, mark.rutland@....com,
        robh+dt@...nel.org, wsa@...-dreams.de, andrew@...id.au,
        benh@...nel.crashing.org, joel@....id.au,
        "Edward A. James" <eajames@...ibm.com>
Subject: [PATCH linux v9 1/5] hwmon: Add core On-Chip Controller support for POWER CPUs

From: "Edward A. James" <eajames@...ibm.com>

Add core support for polling the OCC for it's sensor data and parsing
that data into sensor-specific information.

Signed-off-by: Edward A. James <eajames@...ibm.com>
Signed-off-by: Andrew Jeffery <andrew@...id.au>
---
 Documentation/hwmon/occ    |  42 +++++
 MAINTAINERS                |   7 +
 drivers/hwmon/Kconfig      |   2 +
 drivers/hwmon/Makefile     |   1 +
 drivers/hwmon/occ/Kconfig  |  13 ++
 drivers/hwmon/occ/Makefile |   1 +
 drivers/hwmon/occ/occ.c    | 440 +++++++++++++++++++++++++++++++++++++++++++++
 drivers/hwmon/occ/occ.h    |  77 ++++++++
 drivers/hwmon/occ/scom.h   |  42 +++++
 9 files changed, 625 insertions(+)
 create mode 100644 Documentation/hwmon/occ
 create mode 100644 drivers/hwmon/occ/Kconfig
 create mode 100644 drivers/hwmon/occ/Makefile
 create mode 100644 drivers/hwmon/occ/occ.c
 create mode 100644 drivers/hwmon/occ/occ.h
 create mode 100644 drivers/hwmon/occ/scom.h

diff --git a/Documentation/hwmon/occ b/Documentation/hwmon/occ
new file mode 100644
index 0000000..d1c863b
--- /dev/null
+++ b/Documentation/hwmon/occ
@@ -0,0 +1,42 @@
+=================
+Kernel driver occ
+=================
+
+Supported chips:
+ * POWER8
+ * POWER9
+
+Please note that the driver does not run on these processors. Instead, the
+driver runs on a connected service processor, such as an AST2400. (see the
+BMC - Host Communications section).
+
+Author: Eddie James <eajames@...ibm.com>
+
+Description
+-----------
+
+This driver implements support for the OCC (On-Chip Controller) on the IBM
+POWER8 and POWER9 processors, from a BMC (Baseboard Management Controller). The
+OCC is an embedded processor that provides real time power and thermal
+monitoring.
+
+This driver provides an interface on a BMC to poll OCC sensor data, set user
+power caps, and perform some basic OCC error handling.
+
+Currently, all versions of the OCC support four types of sensor data: power,
+temperature, frequency, and "caps," which indicate limits and thresholds used
+internally on the OCC.
+
+BMC - Host Communications
+-------------------------
+
+For the POWER8 application, the BMC can communicate with the P8 over I2C bus.
+However, to access the OCC register space, any data transfer must use a SCOM
+operation. SCOM is a procedure to initiate a data transfer, typically of 8
+bytes. SCOMs consist of writing a 32-bit command register and then
+reading/writing two 32-bit data registers. This driver implements these
+SCOM operations over I2C bus in order to communicate with the OCC.
+
+For the POWER9 application, the BMC can communicate with the P9 over FSI bus
+and SBE engine. Once again, SCOM operations are required. This driver will
+implement SCOM ops over FSI/SBE. This will require the FSI driver.
diff --git a/MAINTAINERS b/MAINTAINERS
index c776906..4e929fc 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9266,6 +9266,13 @@ T:	git git://linuxtv.org/media_tree.git
 S:	Maintained
 F:	drivers/media/i2c/ov7670.c
 
+ON-CHIP CONTROLLER HWMON POWER8/POWER9 DRIVER
+M:	Eddie James <eajames@...ibm.com>
+L:	openbmc@...ts.ozlabs.org
+S:	Maintained
+F:	Documentation/hwmon/occ
+F:	drivers/hwmon/occ/
+
 ONENAND FLASH DRIVER
 M:	Kyungmin Park <kyungmin.park@...sung.com>
 L:	linux-mtd@...ts.infradead.org
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 0649d53f3..6589933 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1240,6 +1240,8 @@ config SENSORS_NSA320
 	  This driver can also be built as a module. If so, the module
 	  will be called nsa320-hwmon.
 
+source drivers/hwmon/occ/Kconfig
+
 config SENSORS_PCF8591
 	tristate "Philips PCF8591 ADC/DAC"
 	depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 5509edf..5b26067 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -170,6 +170,7 @@ obj-$(CONFIG_SENSORS_WM831X)	+= wm831x-hwmon.o
 obj-$(CONFIG_SENSORS_WM8350)	+= wm8350-hwmon.o
 obj-$(CONFIG_SENSORS_XGENE)	+= xgene-hwmon.o
 
+obj-$(CONFIG_SENSORS_IBM_OCC)	+= occ/
 obj-$(CONFIG_PMBUS)		+= pmbus/
 
 ccflags-$(CONFIG_HWMON_DEBUG_CHIP) := -DDEBUG
diff --git a/drivers/hwmon/occ/Kconfig b/drivers/hwmon/occ/Kconfig
new file mode 100644
index 0000000..61be588
--- /dev/null
+++ b/drivers/hwmon/occ/Kconfig
@@ -0,0 +1,13 @@
+#
+# On Chip Controller configuration
+#
+
+menuconfig SENSORS_IBM_OCC
+	bool "IBM On-Chip Controller"
+	help
+	  If you say yes here you get support to monitor IBM Power CPU
+	  sensors via the On-Chip Controller (OCC), from a service
+	  processor.
+
+	  Generally this is used by management controllers such as a BMC
+	  on an OpenPower system.
diff --git a/drivers/hwmon/occ/Makefile b/drivers/hwmon/occ/Makefile
new file mode 100644
index 0000000..3ed79a5
--- /dev/null
+++ b/drivers/hwmon/occ/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_SENSORS_IBM_OCC) += occ.o
diff --git a/drivers/hwmon/occ/occ.c b/drivers/hwmon/occ/occ.c
new file mode 100644
index 0000000..afc21f8
--- /dev/null
+++ b/drivers/hwmon/occ/occ.c
@@ -0,0 +1,440 @@
+/*
+ * occ.c - OCC hwmon driver
+ *
+ * This file contains the methods and data structures for the OCC hwmon driver.
+ *
+ * Copyright 2017 IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <asm/unaligned.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include "occ.h"
+
+#define OCC_DATA_MAX		4096
+#define OCC_DATA_MIN		40
+#define OCC_BMC_TIMEOUT_MS	20000
+
+/* To generate attn to OCC */
+#define ATTN_DATA		0x0006B035
+
+/* For BMC to read/write SRAM */
+#define OCB_ADDRESS		0x0006B070
+#define OCB_DATA		0x0006B075
+#define OCB_STATUS_CONTROL_AND	0x0006B072
+#define OCB_STATUS_CONTROL_OR	0x0006B073
+
+/* To init OCB */
+#define OCB_AND_INIT0		0xFBFFFFFF
+#define OCB_AND_INIT1		0xFFFFFFFF
+#define OCB_OR_INIT0		0x08000000
+#define OCB_OR_INIT1		0x00000000
+
+/* To generate attention on OCC */
+#define ATTN0			0x01010000
+#define ATTN1			0x00000000
+
+/* OCC return status */
+#define RESP_RETURN_CMD_IN_PRG	0xFF
+#define RESP_RETURN_SUCCESS	0
+#define RESP_RETURN_CMD_INVAL	0x11
+#define RESP_RETURN_CMD_LEN	0x12
+#define RESP_RETURN_DATA_INVAL	0x13
+#define RESP_RETURN_CHKSUM	0x14
+#define RESP_RETURN_OCC_ERR	0x15
+#define RESP_RETURN_STATE	0x16
+
+/* time interval to retry on "command in progress" return status */
+#define CMD_IN_PRG_INT_MS	100
+#define CMD_IN_PRG_RETRIES	(OCC_BMC_TIMEOUT_MS / CMD_IN_PRG_INT_MS)
+
+/* OCC command definitions */
+#define OCC_POLL		0
+#define OCC_SET_USER_POWR_CAP	0x22
+
+/* OCC poll command data */
+#define OCC_POLL_STAT_SENSOR	0x10
+
+/* OCC response data offsets */
+#define RESP_RETURN_STATUS		2
+#define RESP_DATA_LENGTH		3
+#define RESP_HEADER_OFFSET		5
+#define SENSOR_STR_OFFSET		37
+#define NUM_SENSOR_BLOCKS_OFFSET	43
+#define SENSOR_BLOCK_OFFSET		45
+
+/* occ_poll_header
+ * structure to match the raw occ poll response data
+ */
+struct occ_poll_header {
+	u8 status;
+	u8 ext_status;
+	u8 occs_present;
+	u8 config;
+	u8 occ_state;
+	u8 mode;
+	u8 ips_status;
+	u8 error_log_id;
+	u32 error_log_addr_start;
+	u16 error_log_length;
+	u8 reserved2;
+	u8 reserved3;
+	u8 occ_code_level[16];
+	u8 sensor_eye_catcher[6];
+	u8 num_sensor_blocks;
+	u8 sensor_data_version;
+} __attribute__((packed, aligned(4)));
+
+struct occ_response {
+	struct occ_poll_header header;
+	struct occ_blocks data;
+};
+
+struct occ {
+	struct device *dev;
+	void *bus;
+	struct occ_bus_ops bus_ops;
+	struct occ_ops ops;
+	u32 command_addr;
+	u32 response_addr;
+	unsigned long last_updated;
+	struct mutex update_lock;
+	struct occ_response response;
+	bool valid;
+	u8 *raw_data;
+};
+
+static int parse_occ_response(struct occ *driver, u16 num_bytes)
+{
+	int b;
+	int s;
+	unsigned int offset = SENSOR_BLOCK_OFFSET;
+	int sensor_type;
+	u8 num_sensor_blocks;
+	struct sensor_data_block_header *block;
+	void *sensors;
+	struct device *dev = driver->dev;
+	u8 *data = driver->raw_data;
+	struct occ_response *resp = &driver->response;
+
+	/* check if the data is valid */
+	if (strncmp(&data[SENSOR_STR_OFFSET], "SENSOR", 6) != 0) {
+		dev_err(dev, "no SENSOR string in response\n");
+		return -ENODATA;
+	}
+
+	num_sensor_blocks = data[NUM_SENSOR_BLOCKS_OFFSET];
+	if (num_sensor_blocks == 0) {
+		dev_warn(dev, "no sensor blocks available\n");
+		return -ENODATA;
+	}
+
+	memcpy(&resp->header, &data[RESP_HEADER_OFFSET],
+	       sizeof(struct occ_poll_header));
+
+	/* data length starts at actual data */
+	num_bytes += RESP_HEADER_OFFSET;
+
+	/* translate fields > 1 byte */
+	resp->header.error_log_addr_start =
+		be32_to_cpu(resp->header.error_log_addr_start);
+	resp->header.error_log_length =
+		be16_to_cpu(resp->header.error_log_length);
+
+	for (b = 0; b < num_sensor_blocks && b < MAX_OCC_SENSOR_TYPE; b++) {
+		if (offset + sizeof(struct sensor_data_block_header) >
+		    num_bytes) {
+			dev_warn(dev, "exceeded data length\n");
+			return 0;
+		}
+
+		block = (struct sensor_data_block_header *)&data[offset];
+		offset += sizeof(struct sensor_data_block_header);
+
+		if (strncmp(block->sensor_type, "FREQ", 4) == 0)
+			sensor_type = FREQ;
+		else if (strncmp(block->sensor_type, "TEMP", 4) == 0)
+			sensor_type = TEMP;
+		else if (strncmp(block->sensor_type, "POWR", 4) == 0)
+			sensor_type = POWER;
+		else if (strncmp(block->sensor_type, "CAPS", 4) == 0)
+			sensor_type = CAPS;
+		else {
+			dev_warn(dev, "sensor type not supported %.4s\n",
+				block->sensor_type);
+			continue;
+		}
+
+		sensors = &resp->data.blocks[b].sensors;
+		if (!sensors) {
+			/* first poll response */
+			sensors = driver->ops.alloc_sensor(dev, sensor_type,
+							   block->num_sensors);
+			if (!sensors)
+				return -ENOMEM;
+
+			resp->data.blocks[b].sensors = sensors;
+			resp->data.sensor_block_id[sensor_type] = b;
+			resp->data.blocks[b].header = *block;
+		} else if (block->sensor_length !=
+			 resp->data.blocks[b].header.sensor_length) {
+			dev_warn(dev,
+				 "different sensor length than first poll\n");
+			continue;
+		}
+
+		for (s = 0; s < block->num_sensors &&
+		     s < resp->data.blocks[b].header.num_sensors; s++) {
+			if (offset + block->sensor_length > num_bytes) {
+				dev_warn(dev, "exceeded data length\n");
+				return 0;
+			}
+
+			driver->ops.parse_sensor(data, sensors, sensor_type,
+						 offset, s);
+			offset += block->sensor_length;
+		}
+	}
+
+	return 0;
+}
+
+static u8 occ_send_cmd(struct occ *driver, u8 seq, u8 type, u16 length,
+		       const u8 *data, u8 *resp)
+{
+	u32 cmd1, cmd2 = 0;
+	u16 checksum = 0;
+	bool retry = false;
+	int i, rc, tries = 0;
+
+	cmd1 = (seq << 24) | (type << 16) | length;
+	memcpy(&cmd2, data, length);
+	cmd2 <<= ((4 - length) * 8);
+
+	/* checksum: sum of every bytes of cmd1, cmd2 */
+	for (i = 0; i < 4; i++) {
+		checksum += (cmd1 >> (i * 8)) & 0xFF;
+		checksum += (cmd2 >> (i * 8)) & 0xFF;
+	}
+
+	cmd2 |= checksum << ((2 - length) * 8);
+
+	/* Init OCB, the on-chip bridge interface */
+	rc = driver->bus_ops.putscom(driver->bus, OCB_STATUS_CONTROL_OR,
+				     OCB_OR_INIT0, OCB_OR_INIT1);
+	if (rc)
+		goto err;
+
+	rc = driver->bus_ops.putscom(driver->bus, OCB_STATUS_CONTROL_AND,
+				     OCB_AND_INIT0, OCB_AND_INIT1);
+	if (rc)
+		goto err;
+
+	/* Send command, 2nd half of the 64-bit addr is unused (write 0) */
+	rc = driver->bus_ops.putscom(driver->bus, OCB_ADDRESS,
+				     driver->command_addr, 0);
+	if (rc)
+		goto err;
+
+	rc = driver->bus_ops.putscom(driver->bus, OCB_DATA, cmd1, cmd2);
+	if (rc)
+		goto err;
+
+	/* Trigger attention */
+	rc = driver->bus_ops.putscom(driver->bus, ATTN_DATA, ATTN0, ATTN1);
+	if (rc)
+		goto err;
+
+	/* Get response data */
+	rc = driver->bus_ops.putscom(driver->bus, OCB_ADDRESS,
+				     driver->response_addr, 0);
+	if (rc)
+		goto err;
+
+	do {
+		if (retry) {
+			set_current_state(TASK_INTERRUPTIBLE);
+			schedule_timeout(msecs_to_jiffies(CMD_IN_PRG_INT_MS));
+		}
+
+		rc = driver->bus_ops.getscom(driver->bus, OCB_DATA,
+					     (u64 *)resp);
+		if (rc)
+			goto err;
+
+		/* retry if we get "command in progress" return status */
+		retry = resp[RESP_RETURN_STATUS] == RESP_RETURN_CMD_IN_PRG &&
+			tries++ < CMD_IN_PRG_RETRIES;
+	} while (retry);
+
+	/* check the occ response */
+	switch (resp[RESP_RETURN_STATUS]) {
+	case RESP_RETURN_CMD_IN_PRG:
+		rc = -EALREADY;
+		break;
+	case RESP_RETURN_SUCCESS:
+		rc = 0;
+		break;
+	case RESP_RETURN_CMD_INVAL:
+	case RESP_RETURN_CMD_LEN:
+	case RESP_RETURN_DATA_INVAL:
+	case RESP_RETURN_CHKSUM:
+		rc = -EINVAL;
+		break;
+	case RESP_RETURN_OCC_ERR:
+		rc = -EREMOTE;
+		break;
+	default:
+		rc = -EFAULT;
+	}
+
+	if (rc < 0)
+		dev_warn(driver->dev, "occ bad response:%d\n",
+			 resp[RESP_RETURN_STATUS]);
+
+	return rc;
+
+err:
+	dev_err(driver->dev, "scom op failed rc:%d\n", rc);
+	return rc;
+}
+
+static int occ_get_all(struct occ *driver)
+{
+	int i = 0, rc;
+	u8 *occ_data = driver->raw_data;
+	u16 num_bytes;
+	const u8 poll_cmd_data = OCC_POLL_STAT_SENSOR;
+	struct device *dev = driver->dev;
+
+	memset(occ_data, 0, OCC_DATA_MAX);
+
+	rc = occ_send_cmd(driver, 0, OCC_POLL, 1, &poll_cmd_data, occ_data);
+	if (rc)
+		return rc;
+
+	num_bytes = get_unaligned((u16 *)&occ_data[RESP_DATA_LENGTH]);
+	num_bytes = be16_to_cpu(num_bytes);
+
+	if (num_bytes > OCC_DATA_MAX || num_bytes < OCC_DATA_MIN) {
+		dev_err(dev, "bad OCC data length:%d\n", num_bytes);
+		return -EINVAL;
+	}
+
+	/* read remaining data, 8 byte scoms at a time */
+	for (i = 8; i < num_bytes + 8; i += 8) {
+		rc = driver->bus_ops.getscom(driver->bus, OCB_DATA,
+					     (u64 *)&occ_data[i]);
+		if (rc) {
+			dev_err(dev, "getscom op failed rc:%d\n", rc);
+			return rc;
+		}
+	}
+
+	/* don't need more sanity checks; buffer is alloc'd for max response
+	 * size so we just check for valid data in parse_occ_response
+	 */
+	rc = parse_occ_response(driver, num_bytes);
+
+	return rc;
+}
+
+int occ_update_device(struct occ *driver)
+{
+	int rc = 0;
+
+	mutex_lock(&driver->update_lock);
+
+	if (time_after(jiffies, driver->last_updated + HZ) || !driver->valid) {
+		driver->valid = true;
+
+		rc = occ_get_all(driver);
+		if (rc)
+			driver->valid = false;
+
+		driver->last_updated = jiffies;
+	}
+
+	mutex_unlock(&driver->update_lock);
+
+	return rc;
+}
+
+void *occ_get_sensor(struct occ *driver, int sensor_type)
+{
+	int rc;
+	int type_id;
+
+	/* occ_update_device locks the update lock */
+	rc = occ_update_device(driver);
+	if (rc)
+		return ERR_PTR(rc);
+
+	type_id = driver->response.data.sensor_block_id[sensor_type];
+	if (type_id == -1)
+		return ERR_PTR(-ENODATA);
+
+	return driver->response.data.blocks[type_id].sensors;
+}
+
+int occ_get_sensor_field(struct occ *occ, int sensor_type, int sensor_num,
+			 u32 hwmon, long *val)
+{
+	return occ->ops.get_sensor(occ, sensor_type, sensor_num, hwmon, val);
+}
+
+void occ_get_response_blocks(struct occ *occ, struct occ_blocks **blocks)
+{
+	*blocks = &occ->response.data;
+}
+
+int occ_set_user_powercap(struct occ *occ, u16 cap)
+{
+	u8 resp[8];
+
+	cap = cpu_to_be16(cap);
+
+	return occ_send_cmd(occ, 0, OCC_SET_USER_POWR_CAP, 2, (const u8 *)&cap,
+			    resp);
+}
+
+struct occ *occ_init(struct device *dev, void *bus,
+		     const struct occ_bus_ops *bus_ops,
+		     const struct occ_init_data *init)
+{
+	struct occ *driver = devm_kzalloc(dev, sizeof(struct occ), GFP_KERNEL);
+
+	if (!driver)
+		return ERR_PTR(-ENOMEM);
+
+	driver->dev = dev;
+	driver->bus = bus;
+	driver->bus_ops = *bus_ops;
+	driver->ops = *init->ops;
+	driver->command_addr = init->command_addr;
+	driver->response_addr = init->response_addr;
+
+	driver->raw_data = devm_kzalloc(dev, OCC_DATA_MAX, GFP_KERNEL);
+	if (!driver->raw_data)
+		return ERR_PTR(-ENOMEM);
+
+	mutex_init(&driver->update_lock);
+
+	return driver;
+}
+
+MODULE_AUTHOR("Eddie James <eajames@...ibm.com>");
+MODULE_DESCRIPTION("OCC hwmon core driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/hwmon/occ/occ.h b/drivers/hwmon/occ/occ.h
new file mode 100644
index 0000000..6732843
--- /dev/null
+++ b/drivers/hwmon/occ/occ.h
@@ -0,0 +1,77 @@
+/*
+ * occ.h - hwmon OCC driver
+ *
+ * This file contains data structures and function prototypes for common access
+ * between different bus protocols and host systems.
+ *
+ * Copyright 2017 IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef __OCC_H__
+#define __OCC_H__
+
+#include "scom.h"
+
+struct device;
+struct occ;
+
+enum sensor_type {
+	FREQ = 0,
+	TEMP,
+	POWER,
+	CAPS,
+	MAX_OCC_SENSOR_TYPE
+};
+
+/* sensor_data_block_header
+ * structure to match the raw occ sensor block header
+ */
+struct sensor_data_block_header {
+	u8 sensor_type[4];
+	u8 reserved0;
+	u8 sensor_format;
+	u8 sensor_length;
+	u8 num_sensors;
+} __attribute__((packed, aligned(4)));
+
+struct sensor_data_block {
+	struct sensor_data_block_header header;
+	void *sensors;
+};
+
+struct occ_blocks {
+	int sensor_block_id[MAX_OCC_SENSOR_TYPE];
+	struct sensor_data_block blocks[MAX_OCC_SENSOR_TYPE];
+};
+
+struct occ_ops {
+	void (*parse_sensor)(u8 *data, void *sensor, int sensor_type, int off,
+			     int snum);
+	void *(*alloc_sensor)(struct device *dev, int sensor_type,
+			      int num_sensors);
+	int (*get_sensor)(struct occ *driver, int sensor_type, int sensor_num,
+			  u32 hwmon, long *val);
+};
+
+struct occ_init_data {
+	u32 command_addr;
+	u32 response_addr;
+	const struct occ_ops *ops;
+};
+
+struct occ *occ_init(struct device *dev, void *bus,
+		     const struct occ_bus_ops *bus_ops,
+		     const struct occ_init_data *init);
+void *occ_get_sensor(struct occ *occ, int sensor_type);
+int occ_get_sensor_field(struct occ *occ, int sensor_type, int sensor_num,
+			 u32 hwmon, long *val);
+void occ_get_response_blocks(struct occ *occ, struct occ_blocks **blocks);
+int occ_update_device(struct occ *driver);
+int occ_set_user_powercap(struct occ *occ, u16 cap);
+
+#endif /* __OCC_H__ */
diff --git a/drivers/hwmon/occ/scom.h b/drivers/hwmon/occ/scom.h
new file mode 100644
index 0000000..4a891c4
--- /dev/null
+++ b/drivers/hwmon/occ/scom.h
@@ -0,0 +1,42 @@
+/*
+ * scom.h - hwmon OCC driver
+ *
+ * This file contains data structures for scom operations to the OCC
+ *
+ * Copyright 2017 IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef __SCOM_H__
+#define __SCOM_H__
+
+/*
+ * occ_bus_ops - represent the low-level transfer methods to communicate with
+ * the OCC.
+ *
+ * getscom - OCC scom read 8 bytes
+ * @bus: handle to slave device
+ * @address: address
+ * @data: where to store data read from slave; buffer size must be at least
+ * eight bytes.
+ *
+ * Returns 0 on success or a negative errno on error
+ *
+ * putscom - OCC scom write
+ * @bus: handle to slave device
+ * @address: address
+ * @data0: first data word to write
+ * @data1: second data word to write
+ *
+ * Returns 0 on success or a negative errno on error
+ */
+struct occ_bus_ops {
+	int (*getscom)(void *bus, u32 address, u64 *data);
+	int (*putscom)(void *bus, u32 address, u32 data0, u32 data1);
+};
+
+#endif /* __SCOM_H__ */
-- 
1.8.3.1

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