[PATCH linux dev-4.10 v3 2/2] drivers: fsi: sbefifo: Add OCC driver

[Eddie James <eajames@linux.vnet.ibm.com>]

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

This driver provides an atomic communications channel between the OCC on
the POWER9 processor and a service processor (a BMC). The driver is
dependent on the FSI SBEFIFO driver to get hardware access to the OCC
SRAM.

The format of the communication is a command followed by a response.
Since the command and response must be performed atomically, the driver
will perform this operations asynchronously. In this way, a write
operation starts the command, and a read will gather the response data
once it is complete.

Signed-off-by: Edward A. James <eajames@us.ibm.com>
---
 drivers/fsi/Kconfig  |   6 +
 drivers/fsi/Makefile |   1 +
 drivers/fsi/occ.c    | 784 +++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 791 insertions(+)
 create mode 100644 drivers/fsi/occ.c

diff --git a/drivers/fsi/Kconfig b/drivers/fsi/Kconfig
index 39527fa..d56b582 100644
--- a/drivers/fsi/Kconfig
+++ b/drivers/fsi/Kconfig
@@ -36,6 +36,12 @@ config FSI_SBEFIFO
 	---help---
 	This option enables an FSI based SBEFIFO device driver.
 
+config OCCFIFO
+	tristate "OCC SBEFIFO client device driver"
+	depends on FSI_SBEFIFO
+	---help---
+	This option enables an SBEFIFO based OCC device driver.
+
 endif
 
 endmenu
diff --git a/drivers/fsi/Makefile b/drivers/fsi/Makefile
index 851182e..7f5ca61 100644
--- a/drivers/fsi/Makefile
+++ b/drivers/fsi/Makefile
@@ -4,3 +4,4 @@ obj-$(CONFIG_FSI_MASTER_HUB) += fsi-master-hub.o
 obj-$(CONFIG_FSI_MASTER_GPIO) += fsi-master-gpio.o
 obj-$(CONFIG_FSI_SCOM) += fsi-scom.o
 obj-$(CONFIG_FSI_SBEFIFO) += fsi-sbefifo.o
+obj-$(CONFIG_OCCFIFO) += occ.o
diff --git a/drivers/fsi/occ.c b/drivers/fsi/occ.c
new file mode 100644
index 0000000..fce5824
--- /dev/null
+++ b/drivers/fsi/occ.c
@@ -0,0 +1,784 @@
+/*
+ * 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/device.h>
+#include <linux/err.h>
+#include <linux/fsi-sbefifo.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/wait.h>
+#include <linux/workqueue.h>
+
+#define OCC_SRAM_BYTES		4096
+#define OCC_CMD_DATA_BYTES	4090
+#define OCC_RESP_DATA_BYTES	4089
+#define OCC_SRAM_DELAY_MS	25
+
+struct occ {
+	struct device *sbefifo;
+	char name[32];
+	int idx;
+	struct miscdevice mdev;
+	struct list_head xfrs;
+	spinlock_t list_lock;
+	struct mutex occ_lock;
+	struct work_struct work;
+};
+
+#define to_occ(x)	container_of((x), struct occ, mdev)
+
+struct occ_command {
+	u8 seq_no;
+	u8 cmd_type;
+	u16 data_length;
+	u8 data[OCC_CMD_DATA_BYTES];
+	u16 checksum;
+} __packed;
+
+struct occ_response {
+	u8 seq_no;
+	u8 cmd_type;
+	u8 return_status;
+	u16 data_length;
+	u8 data[OCC_RESP_DATA_BYTES];
+	u16 checksum;
+} __packed;
+
+/*
+ * transfer flags are NOT mutually exclusive
+ * 
+ * Initial flags are none; transfer is created and queued from write(). All
+ * 	flags are cleared when the transfer is completed by closing the file or
+ * 	reading all of the available response data.
+ * XFR_IN_PROGRESS is set when a transfer is started from occ_worker_putsram,
+ * 	and cleared if the transfer fails or occ_worker_getsram completes.
+ * XFR_COMPLETE is set when a transfer fails or finishes occ_worker_getsram.
+ * XFR_CANCELED is set when the transfer's client is released.
+ * XFR_WAITING is set from read() if the transfer isn't complete and
+ * 	NONBLOCKING wasn't specified. Cleared in read() when transfer completes
+ * 	or fails.
+ */
+enum {
+	XFR_IN_PROGRESS,
+	XFR_COMPLETE,
+	XFR_CANCELED,
+	XFR_WAITING,
+};
+
+struct occ_xfr {
+	struct list_head link;
+	int rc;
+	u8 buf[OCC_SRAM_BYTES];
+	size_t cmd_data_length;
+	size_t resp_data_length;
+	unsigned long flags;
+};
+
+/*
+ * client flags
+ *
+ * CLIENT_NONBLOCKING is set during open() if the file was opened with the
+ * 	O_NONBLOCKING flag.
+ * CLIENT_XFR_PENDING is set during write() and cleared when all data has been
+ * 	read.
+ */
+enum {
+	CLIENT_NONBLOCKING,
+	CLIENT_XFR_PENDING,
+};
+
+struct occ_client {
+	struct occ *occ;
+	struct occ_xfr xfr;
+	spinlock_t lock;
+	wait_queue_head_t wait;
+	size_t read_offset;
+	unsigned long flags;
+};
+
+#define to_client(x)	container_of((x), struct occ_client, xfr)
+
+static struct workqueue_struct *occ_wq;
+
+static DEFINE_IDA(occ_ida);
+
+static void occ_enqueue_xfr(struct occ_xfr *xfr)
+{
+	int empty;
+	struct occ_client *client = to_client(xfr);
+	struct occ *occ = client->occ;
+
+	spin_lock_irq(&occ->list_lock);
+	empty = list_empty(&occ->xfrs);
+	list_add_tail(&xfr->link, &occ->xfrs);
+	spin_unlock(&occ->list_lock);
+
+	if (empty)
+		queue_work(occ_wq, &occ->work);
+}
+
+static struct occ_client *occ_open_common(struct occ *occ, unsigned long flags)
+{
+	struct occ_client *client;
+
+	client = kzalloc(sizeof(*client), GFP_KERNEL);
+	if (!client)
+		return NULL;
+
+	client->occ = occ;
+	spin_lock_init(&client->lock);
+	init_waitqueue_head(&client->wait);
+
+	if (flags & O_NONBLOCK)
+		set_bit(CLIENT_NONBLOCKING, &client->flags);
+
+	return client;
+}
+
+static int occ_open(struct inode *inode, struct file *file)
+{
+	struct occ_client *client;
+	struct miscdevice *mdev = file->private_data;
+	struct occ *occ = to_occ(mdev);
+
+	client = occ_open_common(occ, file->f_flags);
+	if (!client)
+		return -ENOMEM;
+
+	file->private_data = client;
+
+	return 0;
+}
+
+static ssize_t occ_read_common(struct occ_client *client, char __user *ubuf,
+			       char *kbuf, size_t len)
+{
+	int rc;
+	size_t bytes;
+	struct occ_xfr *xfr = &client->xfr;
+
+	if (len > OCC_SRAM_BYTES)
+		return -EINVAL;
+
+	spin_lock_irq(&client->lock);
+	if (!test_bit(CLIENT_XFR_PENDING, &client->flags)) {
+		/* we just finished reading all data, return 0 */
+		if (client->read_offset) {
+			rc = 0;
+			client->read_offset = 0;
+		} else
+			rc = -ENOMSG;
+
+		goto done;
+	}
+
+	if (!test_bit(XFR_COMPLETE, &xfr->flags)) {
+		if (test_bit(CLIENT_NONBLOCKING, &client->flags)) {
+			rc = -ERESTARTSYS;
+			goto done;
+		}
+
+		set_bit(XFR_WAITING, &xfr->flags);
+		spin_unlock(&client->lock);
+
+		rc = wait_event_interruptible(client->wait,
+			test_bit(XFR_COMPLETE, &xfr->flags) ||
+			test_bit(XFR_CANCELED, &xfr->flags));
+
+		spin_lock_irq(&client->lock);
+		if (test_bit(XFR_CANCELED, &xfr->flags)) {
+			spin_unlock(&client->lock);
+			kfree(client);
+			return -EBADFD;
+		}
+
+		clear_bit(XFR_WAITING, &xfr->flags);
+		if (!test_bit(XFR_COMPLETE, &xfr->flags)) {
+			rc = -EINTR;
+			goto done;
+		}
+	}
+
+	if (xfr->rc) {
+		rc = xfr->rc;
+		goto done;
+	}
+
+	bytes = min(len, xfr->resp_data_length - client->read_offset);
+	if (ubuf) {
+		if (copy_to_user(ubuf, &xfr->buf[client->read_offset], bytes)) {
+			rc = -EFAULT;
+			goto done;
+		}
+	} else
+		memcpy(kbuf, &xfr->buf[client->read_offset], bytes);
+
+	client->read_offset += bytes;
+
+	/* xfr done */
+	if (client->read_offset == xfr->resp_data_length)
+		clear_bit(CLIENT_XFR_PENDING, &client->flags);
+
+	rc = bytes;
+
+done:
+	spin_unlock(&client->lock);
+	return rc;
+}
+
+static ssize_t occ_read(struct file *file, char __user *buf, size_t len,
+			loff_t *offset)
+{
+	struct occ_client *client = file->private_data;
+
+	/* check this ahead of time so we don't go changing the xfr state
+	 * needlessly
+	 */
+	if (!access_ok(VERIFY_WRITE, buf, len))
+		return -EFAULT;
+
+	return occ_read_common(client, buf, NULL, len);
+}
+
+static ssize_t occ_write_common(struct occ_client *client,
+				const char __user *ubuf, const char *kbuf,
+				size_t len)
+{
+	int rc;
+	unsigned int i;
+	u16 data_length, checksum = 0;
+	struct occ_xfr *xfr = &client->xfr;
+
+	if (len > (OCC_CMD_DATA_BYTES + 3) || len < 3)
+		return -EINVAL;
+
+	spin_lock_irq(&client->lock);
+	if (test_and_set_bit(CLIENT_XFR_PENDING, &client->flags)) {
+		rc = -EBUSY;
+		goto done;
+	}
+
+	/* clear out the transfer */
+	memset(xfr, 0, sizeof(*xfr));
+
+	xfr->buf[0] = 1;
+
+	if (ubuf) {
+		if (copy_from_user(&xfr->buf[1], ubuf, len)) {
+			kfree(xfr);
+			rc = -EFAULT;
+			goto done;
+		}
+	} else
+		memcpy(&xfr->buf[1], kbuf, len);
+
+	data_length = (xfr->buf[2] << 8) + xfr->buf[3];
+	if (data_length > OCC_CMD_DATA_BYTES) {
+		kfree(xfr);
+		rc = -EINVAL;
+		goto done;
+	}
+
+	for (i = 0; i < data_length + 4; ++i)
+		checksum += xfr->buf[i];
+
+	xfr->buf[data_length + 4] = checksum >> 8;
+	xfr->buf[data_length + 5] = checksum & 0xFF;
+
+	xfr->cmd_data_length = data_length + 6;
+	client->read_offset = 0;
+
+	occ_enqueue_xfr(xfr);
+
+	rc = len;
+
+done:
+	spin_unlock(&client->lock);
+	return rc;
+}
+
+static ssize_t occ_write(struct file *file, const char __user *buf,
+			 size_t len, loff_t *offset)
+{
+	struct occ_client *client = file->private_data;
+
+	/* check this ahead of time so we don't go changing the xfr state
+	 * needlessly
+	 */
+	if (!access_ok(VERIFY_READ, buf, len))
+		return -EFAULT;
+
+	return occ_write_common(client, buf, NULL, len);
+}
+
+static int occ_release_common(struct occ_client *client)
+{
+	struct occ_xfr *xfr = &client->xfr;
+	struct occ *occ = client->occ;
+
+	spin_lock_irq(&client->lock);
+	if (!test_bit(CLIENT_XFR_PENDING, &client->flags)) {
+		spin_unlock(&client->lock);
+		kfree(client);
+		return 0;
+	}
+
+	spin_lock_irq(&occ->list_lock);
+	set_bit(XFR_CANCELED, &xfr->flags);
+	if (!test_bit(XFR_IN_PROGRESS, &xfr->flags)) {
+		/* already deleted from list if complete */
+		if (!test_bit(XFR_COMPLETE, &xfr->flags))
+			list_del(&xfr->link);
+
+		spin_unlock(&occ->list_lock);
+
+		if (test_bit(XFR_WAITING, &xfr->flags)) {
+			/* blocking read; let reader clean up */
+			wake_up_interruptible(&client->wait);
+			spin_unlock(&client->lock);
+			return 0;
+		}
+
+		spin_unlock(&client->lock);
+		kfree(client);
+		return 0;
+	}
+
+	/* operation is in progress; let worker clean up*/
+	spin_unlock(&occ->list_lock);
+	spin_unlock(&client->lock);
+	return 0;
+}
+
+static int occ_release(struct inode *inode, struct file *file)
+{
+	struct occ_client *client = file->private_data;
+
+	return occ_release_common(client);
+}
+
+static const struct file_operations occ_fops = {
+	.owner = THIS_MODULE,
+	.open = occ_open,
+	.read = occ_read,
+	.write = occ_write,
+	.release = occ_release,
+};
+
+static int occ_write_sbefifo(struct sbefifo_client *client, const char *buf,
+			     ssize_t len)
+{
+	int rc;
+	ssize_t total = 0;
+
+	do {
+		rc = sbefifo_drv_write(client, &buf[total], len - total);
+		if (rc < 0)
+			return rc;
+		else if (!rc)
+			break;
+
+		total += rc;
+	} while (total < len);
+
+	return (total == len) ? 0 : -EMSGSIZE;
+}
+
+static int occ_read_sbefifo(struct sbefifo_client *client, char *buf,
+			    ssize_t len)
+{
+	int rc;
+	ssize_t total = 0;
+
+	do {
+		rc = sbefifo_drv_read(client, &buf[total], len - total);
+		if (rc < 0)
+			return rc;
+		else if (!rc)
+			break;
+
+		total += rc;
+	} while (total < len);
+
+	return (total == len) ? 0 : -EMSGSIZE;
+}
+
+static int occ_getsram(struct device *sbefifo, u32 address, u8 *data,
+		       ssize_t len)
+{
+	int rc;
+	u8 *resp;
+	u32 buf[5];
+	u32 data_len = ((len + 7) / 8) * 8;
+	struct sbefifo_client *client;
+
+	buf[0] = cpu_to_be32(0x5);
+	buf[1] = cpu_to_be32(0xa403);
+	buf[2] = cpu_to_be32(1);
+	buf[3] = cpu_to_be32(address);
+	buf[4] = cpu_to_be32(data_len);
+
+	client = sbefifo_drv_open(sbefifo, 0);
+	if (!client)
+		return -ENODEV;
+
+	rc = occ_write_sbefifo(client, (const char *)buf, sizeof(buf));
+	if (rc)
+		goto done;
+	
+	resp = kzalloc(data_len, GFP_KERNEL);
+	if (!resp) {
+		rc = -ENOMEM;
+		goto done;
+	}
+
+	rc = occ_read_sbefifo(client, (char *)resp, data_len);
+	if (rc)
+		goto free;
+
+	/* check for good response */
+	rc = occ_read_sbefifo(client, (char *)buf, 8);
+	if (rc)
+		goto free;
+
+	if ((be32_to_cpu(buf[0]) == data_len) &&
+	    (be32_to_cpu(buf[1]) == 0xC0DEA403))
+		memcpy(data, resp, len);
+	else
+		rc = -EFAULT;
+
+free:
+	kfree(resp);
+
+done:
+	sbefifo_drv_release(client);
+	return rc;
+}
+
+static int occ_putsram(struct device *sbefifo, u32 address, u8 *data,
+		       ssize_t len)
+{
+	int rc;
+	u32 *buf;
+	u32 data_len = ((len + 7) / 8) * 8;
+	size_t cmd_len = data_len + 20;
+	struct sbefifo_client *client;
+
+	buf = kzalloc(cmd_len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	buf[0] = cpu_to_be32(0x5 + (data_len / 4));
+	buf[1] = cpu_to_be32(0xa404);
+	buf[2] = cpu_to_be32(1);
+	buf[3] = cpu_to_be32(address);
+	buf[4] = cpu_to_be32(data_len);
+
+	memcpy(&buf[5], data, len);
+
+	client = sbefifo_drv_open(sbefifo, 0);
+	if (!client) {
+		rc = -ENODEV;
+		goto free;
+	}
+
+	rc = occ_write_sbefifo(client, (const char *)buf, cmd_len);
+	if (rc)
+		goto done;
+
+	rc = occ_read_sbefifo(client, (char *)buf, 8);
+	if (rc)
+		goto done;
+
+	/* check for good response */
+	if ((be32_to_cpu(buf[0]) != data_len) ||
+	    (be32_to_cpu(buf[1]) != 0xC0DEA404))
+		rc = -EFAULT;
+
+done:
+	sbefifo_drv_release(client);
+free:
+	kfree(buf);
+	return rc;
+}
+
+static int occ_trigger_attn(struct device *sbefifo)
+{
+	int rc;
+	u32 buf[6];
+	struct sbefifo_client *client;
+
+	buf[0] = cpu_to_be32(0x6);
+	buf[1] = cpu_to_be32(0xa202);
+	buf[2] = 0;
+	buf[3] = cpu_to_be32(0x6D035);
+	buf[4] = cpu_to_be32(0x20010000);
+	buf[5] = 0;
+
+	client = sbefifo_drv_open(sbefifo, 0);
+	if (!client)
+		return -ENODEV;
+
+	rc = occ_write_sbefifo(client, (const char *)buf, sizeof(buf));
+	if (rc)
+		goto done;
+
+	rc = occ_read_sbefifo(client, (char *)buf, 8);
+	if (rc)
+		goto done;
+
+	/* check for good response */
+	if ((be32_to_cpu(buf[0]) != 0xC0DEA202) ||
+	    (be32_to_cpu(buf[1]) & 0x0FFFFFFF))
+		rc = -EFAULT;
+
+done:
+	sbefifo_drv_release(client);
+
+	return rc;
+}
+
+static void occ_worker(struct work_struct *work)
+{
+	int rc = 0, empty, waiting, canceled;
+	u16 resp_data_length;
+	struct occ_xfr *xfr;
+	struct occ_client *client;
+	struct occ *occ = container_of(work, struct occ, work);
+	struct device *sbefifo = occ->sbefifo;
+
+again:
+	spin_lock_irq(&occ->list_lock);
+	xfr = list_first_entry(&occ->xfrs, struct occ_xfr, link);
+	if (!xfr) {
+		spin_unlock(&occ->list_lock);
+		return;
+	}
+
+	set_bit(XFR_IN_PROGRESS, &xfr->flags);
+
+	spin_unlock(&occ->list_lock);
+	mutex_lock(&occ->occ_lock);
+
+	rc = occ_putsram(sbefifo, 0xFFFBE000, xfr->buf,
+			 xfr->cmd_data_length);
+	if (rc)
+		goto done;
+
+	rc = occ_trigger_attn(sbefifo);
+	if (rc)
+		goto done;
+
+	rc = occ_getsram(sbefifo, 0xFFFBF000, xfr->buf, 8);
+	if (rc)
+		goto done;
+
+	resp_data_length = (xfr->buf[3] << 8) + xfr->buf[4];
+	if (resp_data_length > OCC_RESP_DATA_BYTES) {
+		rc = -EDOM;
+		goto done;
+	}
+
+	/* already got 3 bytes resp, also need 2 bytes checksum */
+	rc = occ_getsram(sbefifo, 0xFFFBF008, &xfr->buf[8],
+			 resp_data_length - 1);
+	if (rc)
+		goto done;
+
+	xfr->resp_data_length = resp_data_length + 7;
+
+done:
+	mutex_unlock(&occ->occ_lock);
+
+	xfr->rc = rc;
+	client = to_client(xfr);
+
+	/* lock client to prevent race with read() */
+	spin_lock_irq(&client->lock);
+	set_bit(XFR_COMPLETE, &xfr->flags);
+	waiting = test_bit(XFR_WAITING, &xfr->flags);
+	spin_unlock(&client->lock);
+
+	spin_lock_irq(&occ->list_lock);
+	clear_bit(XFR_IN_PROGRESS, &xfr->flags);
+	list_del(&xfr->link);
+	empty = list_empty(&occ->xfrs);
+	canceled = test_bit(XFR_CANCELED, &xfr->flags);
+	spin_unlock(&occ->list_lock);
+
+	if (waiting)
+		wake_up_interruptible(&client->wait);
+	else if (canceled)
+		kfree(client);
+
+	if (!empty)
+		goto again;
+}
+
+struct occ_client *occ_drv_open(struct device *dev, unsigned long flags)
+{
+	struct occ *occ = dev_get_drvdata(dev);
+
+	return occ_open_common(occ, flags);
+}
+EXPORT_SYMBOL_GPL(occ_drv_open);
+
+int occ_drv_read(struct occ_client *client, char *buf, size_t len)
+{
+	return occ_read_common(client, NULL, buf, len);
+}
+EXPORT_SYMBOL_GPL(occ_drv_read);
+
+int occ_drv_write(struct occ_client *client, const char *buf, size_t len)
+{
+	return occ_write_common(client, NULL, buf, len);
+}
+EXPORT_SYMBOL_GPL(occ_drv_write);
+
+void occ_drv_release(struct occ_client *client)
+{
+	occ_release_common(client);
+}
+EXPORT_SYMBOL_GPL(occ_drv_release);
+
+static int occ_unregister_child(struct device *dev, void *data)
+{
+	struct platform_device *child = to_platform_device(dev);
+
+	of_device_unregister(child);
+	if (dev->of_node)
+		of_node_clear_flag(dev->of_node, OF_POPULATED);
+
+	return 0;
+}
+
+static int occ_probe(struct platform_device *pdev)
+{
+	int rc, child_idx = 0;
+	u32 reg;
+	struct occ *occ;
+	struct device_node *np;
+	struct platform_device *child;
+	struct device *dev = &pdev->dev;
+	char child_name[32];
+
+	occ = devm_kzalloc(dev, sizeof(*occ), GFP_KERNEL);
+	if (!occ)
+		return -ENOMEM;
+
+	occ->sbefifo = dev->parent;
+	INIT_LIST_HEAD(&occ->xfrs);
+	spin_lock_init(&occ->list_lock);
+	mutex_init(&occ->occ_lock);
+	INIT_WORK(&occ->work, occ_worker);
+
+	platform_set_drvdata(pdev, occ);
+
+	if (dev->of_node) {
+		rc = of_property_read_u32(dev->of_node, "reg", &reg);
+		if (!rc) {
+			/* make sure we don't have a duplicate from dts */
+			occ->idx = ida_simple_get(&occ_ida, reg, reg + 1,
+						  GFP_KERNEL);
+			if (occ->idx < 0)
+				occ->idx = ida_simple_get(&occ_ida, 1, INT_MAX,
+							  GFP_KERNEL);
+		} else
+			occ->idx = ida_simple_get(&occ_ida, 1, INT_MAX,
+						  GFP_KERNEL);
+
+		/* create platform devs for dts child nodes (hwmon, etc) */
+		for_each_child_of_node(dev->of_node, np) {
+			snprintf(child_name, sizeof(child_name), "occ%d-dev%d",
+				 occ->idx, child_idx++);
+			child = of_platform_device_create(np, child_name, dev);
+			if (!child)
+				dev_warn(dev,
+					 "failed to create child node dev\n");
+		}
+	} else
+		occ->idx = ida_simple_get(&occ_ida, 1, INT_MAX, GFP_KERNEL);
+
+	snprintf(occ->name, sizeof(occ->name), "occ%d", occ->idx);
+	occ->mdev.fops = &occ_fops;
+	occ->mdev.minor = MISC_DYNAMIC_MINOR;
+	occ->mdev.name = occ->name;
+	occ->mdev.parent = dev;
+
+	rc = misc_register(&occ->mdev);
+	if (rc) {
+		dev_err(dev, "failed to register miscdevice\n");
+		return rc;
+	}
+
+	return 0;
+}
+
+static int occ_remove(struct platform_device *pdev)
+{
+	struct occ_xfr *xfr, *tmp;
+	struct occ *occ = platform_get_drvdata(pdev);
+	struct occ_client *client;
+
+	flush_work(&occ->work);
+
+	misc_deregister(&occ->mdev);
+
+	device_for_each_child(&pdev->dev, NULL, occ_unregister_child);
+
+	ida_simple_remove(&occ_ida, occ->idx);
+
+	return 0;
+}
+
+static const struct of_device_id occ_match[] = {
+	{ .compatible = "ibm,p9-occ" },
+	{ },
+};
+
+static struct platform_driver occ_driver = {
+	.driver = {
+		.name = "occ",
+		.of_match_table	= occ_match,
+	},
+	.probe	= occ_probe,
+	.remove = occ_remove,
+};
+
+static int occ_init(void)
+{
+	occ_wq = create_singlethread_workqueue("occ");
+	if (!occ_wq)
+		return -ENOMEM;
+
+	return platform_driver_register(&occ_driver);
+}
+
+static void occ_exit(void)
+{
+	destroy_workqueue(occ_wq);
+
+	platform_driver_unregister(&occ_driver);
+}
+
+module_init(occ_init);
+module_exit(occ_exit);
+
+MODULE_AUTHOR("Eddie James <eajames@us.ibm.com>");
+MODULE_DESCRIPTION("BMC P9 OCC driver");
+MODULE_LICENSE("GPL");
-- 
1.8.3.1