bus: fsl-mc: add fsl-mc userspace support

Adding userspace support for the MC (Management Complex) means exporting
an ioctl capable device file representing the root resource container.

This new functionality in the fsl-mc bus driver intends to provide
userspace applications an interface to interact with the MC firmware.

Commands that are composed in userspace are sent to the MC firmware
through the FSL_MC_SEND_MC_COMMAND ioctl.  By default the implicit MC
I/O portal is used for this operation, but if the implicit one is busy,
a dynamic portal is allocated and then freed upon execution.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>

Documentation/ioctl/ioctl-number.rst

@@ -180,6 +180,7 @@ Code  Seq#    Include File                                           Comments
 'R'   00-1F  linux/random.h                                          conflict!
 'R'   01     linux/rfkill.h                                          conflict!
 'R'   C0-DF  net/bluetooth/rfcomm.h
+'R'   E0     uapi/linux/fsl_mc.h
 'S'   all    linux/cdrom.h                                           conflict!
 'S'   80-81  scsi/scsi_ioctl.h                                       conflict!
 'S'   82-FF  scsi/scsi.h                                             conflict!

drivers/bus/fsl-mc/Kconfig

@@ -14,3 +14,10 @@ config FSL_MC_BUS
 	  architecture.  The fsl-mc bus driver handles discovery of
 	  DPAA2 objects (which are represented as Linux devices) and
 	  binding objects to drivers.
+
+config FSL_MC_UAPI_SUPPORT
+	bool "Management Complex (MC) userspace support"
+	depends on FSL_MC_BUS
+	help
+	  Provides userspace support for creating/destroying/configuring
+	  DPAA2 objects in the Management Complex.

drivers/bus/fsl-mc/Makefile

@@ -16,3 +16,6 @@ mc-bus-driver-objs := fsl-mc-bus.o \
 		      fsl-mc-allocator.o \
 		      fsl-mc-msi.o \
 		      dpmcp.o
+
+# MC userspace support
+obj-$(CONFIG_FSL_MC_UAPI_SUPPORT) += fsl-mc-uapi.o

drivers/bus/fsl-mc/dprc-driver.c

@@ -647,6 +647,12 @@ static int dprc_probe(struct fsl_mc_device *mc_dev)
 		} else {
 			dev_set_msi_domain(&mc_dev->dev, mc_msi_domain);
 			msi_domain_set = true;
+
+			error = fsl_mc_uapi_create_device_file(mc_bus);
+			if (error < 0) {
+				error = -EPROBE_DEFER;
+				goto error_cleanup_msi_domain;
+			}
 		}
 	}
 
@@ -654,7 +660,7 @@ static int dprc_probe(struct fsl_mc_device *mc_dev)
 			  &mc_dev->mc_handle);
 	if (error < 0) {
 		dev_err(&mc_dev->dev, "dprc_open() failed: %d\n", error);
-		goto error_cleanup_msi_domain;
+		goto error_cleanup_uapi;
 	}
 
 	error = dprc_get_attributes(mc_dev->mc_io, 0, mc_dev->mc_handle,
@@ -706,6 +712,10 @@ static int dprc_probe(struct fsl_mc_device *mc_dev)
 error_cleanup_open:
 	(void)dprc_close(mc_dev->mc_io, 0, mc_dev->mc_handle);
 
+error_cleanup_uapi:
+	if (fsl_mc_is_root_dprc(&mc_dev->dev))
+		fsl_mc_uapi_remove_device_file(mc_bus);
+
 error_cleanup_msi_domain:
 	if (msi_domain_set)
 		dev_set_msi_domain(&mc_dev->dev, NULL);
@@ -774,6 +784,8 @@ static int dprc_remove(struct fsl_mc_device *mc_dev)
 	if (!fsl_mc_is_root_dprc(&mc_dev->dev)) {
 		fsl_destroy_mc_io(mc_dev->mc_io);
 		mc_dev->mc_io = NULL;
+	} else {
+		fsl_mc_uapi_remove_device_file(mc_bus);
 	}
 
 	dev_info(&mc_dev->dev, "DPRC device unbound from driver");

drivers/bus/fsl-mc/fsl-mc-private.h

@@ -10,6 +10,8 @@
 
 #include <linux/fsl/mc.h>
 #include <linux/mutex.h>
+#include <linux/ioctl.h>
+#include <linux/miscdevice.h>
 
 /*
  * Data Path Management Complex (DPMNG) General API
@@ -504,6 +506,22 @@ struct fsl_mc_resource_pool {
 	struct fsl_mc_bus *mc_bus;
 };
 
+/**
+ * struct fsl_mc_uapi - information associated with a device file
+ * @misc: struct miscdevice linked to the root dprc
+ * @device: newly created device in /dev
+ * @mutex: mutex lock to serialize the open/release operations
+ * @local_instance_in_use: local MC I/O instance in use or not
+ * @static_mc_io: pointer to the static MC I/O object
+ */
+struct fsl_mc_uapi {
+	struct miscdevice misc;
+	struct device *device;
+	struct mutex mutex; /* serialize open/release operations */
+	u32 local_instance_in_use;
+	struct fsl_mc_io *static_mc_io;
+};
+
 /**
  * struct fsl_mc_bus - logical bus that corresponds to a physical DPRC
  * @mc_dev: fsl-mc device for the bus device itself.
@@ -513,6 +531,7 @@ struct fsl_mc_resource_pool {
  * @irq_resources: Pointer to array of IRQ objects for the IRQ pool
  * @scan_mutex: Serializes bus scanning
  * @dprc_attr: DPRC attributes
+ * @uapi_misc: struct that abstracts the interaction with userspace
  */
 struct fsl_mc_bus {
 	struct fsl_mc_device mc_dev;
@@ -520,6 +539,7 @@ struct fsl_mc_bus {
 	struct fsl_mc_device_irq *irq_resources;
 	struct mutex scan_mutex;    /* serializes bus scanning */
 	struct dprc_attributes dprc_attr;
+	struct fsl_mc_uapi uapi_misc;
 };
 
 #define to_fsl_mc_bus(_mc_dev) \
@@ -574,4 +594,23 @@ void fsl_destroy_mc_io(struct fsl_mc_io *mc_io);
 
 bool fsl_mc_is_root_dprc(struct device *dev);
 
+#ifdef CONFIG_FSL_MC_UAPI_SUPPORT
+
+int fsl_mc_uapi_create_device_file(struct fsl_mc_bus *mc_bus);
+
+void fsl_mc_uapi_remove_device_file(struct fsl_mc_bus *mc_bus);
+
+#else
+
+static inline int fsl_mc_uapi_create_device_file(struct fsl_mc_bus *mc_bus)
+{
+	return 0;
+}
+
+static inline void fsl_mc_uapi_remove_device_file(struct fsl_mc_bus *mc_bus)
+{
+}
+
+#endif
+
 #endif /* _FSL_MC_PRIVATE_H_ */

drivers/bus/fsl-mc/fsl-mc-uapi.c

@@ -0,0 +1,168 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Management Complex (MC) userspace support
+ *
+ * Copyright 2018 NXP
+ *
+ */
+
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+#include <linux/miscdevice.h>
+
+#include "fsl-mc-private.h"
+
+struct uapi_priv_data {
+	struct fsl_mc_uapi *uapi;
+	struct fsl_mc_io *mc_io;
+};
+
+static int fsl_mc_uapi_send_command(unsigned long arg,
+				    struct fsl_mc_io *mc_io)
+{
+	struct fsl_mc_command mc_cmd;
+	int error;
+
+	error = copy_from_user(&mc_cmd, (void __user *)arg, sizeof(mc_cmd));
+	if (error)
+		return -EFAULT;
+
+	error = mc_send_command(mc_io, &mc_cmd);
+	if (error)
+		return error;
+
+	error = copy_to_user((void __user *)arg, &mc_cmd, sizeof(mc_cmd));
+	if (error)
+		return -EFAULT;
+
+	return 0;
+}
+
+static int fsl_mc_uapi_dev_open(struct inode *inode, struct file *filep)
+{
+	struct fsl_mc_device *root_mc_device;
+	struct uapi_priv_data *priv_data;
+	struct fsl_mc_io *dynamic_mc_io;
+	struct fsl_mc_uapi *mc_uapi;
+	struct fsl_mc_bus *mc_bus;
+	int error;
+
+	priv_data = kzalloc(sizeof(*priv_data), GFP_KERNEL);
+	if (!priv_data)
+		return -ENOMEM;
+
+	mc_uapi = container_of(filep->private_data, struct fsl_mc_uapi, misc);
+	mc_bus = container_of(mc_uapi, struct fsl_mc_bus, uapi_misc);
+	root_mc_device = &mc_bus->mc_dev;
+
+	mutex_lock(&mc_uapi->mutex);
+
+	if (!mc_uapi->local_instance_in_use) {
+		priv_data->mc_io = mc_uapi->static_mc_io;
+		mc_uapi->local_instance_in_use = 1;
+	} else {
+		error = fsl_mc_portal_allocate(root_mc_device, 0,
+					       &dynamic_mc_io);
+		if (error) {
+			dev_dbg(&root_mc_device->dev,
+				"Could not allocate MC portal\n");
+			goto error_portal_allocate;
+		}
+
+		priv_data->mc_io = dynamic_mc_io;
+	}
+	priv_data->uapi = mc_uapi;
+	filep->private_data = priv_data;
+
+	mutex_unlock(&mc_uapi->mutex);
+
+	return 0;
+
+error_portal_allocate:
+	mutex_unlock(&mc_uapi->mutex);
+
+	return error;
+}
+
+static int fsl_mc_uapi_dev_release(struct inode *inode, struct file *filep)
+{
+	struct uapi_priv_data *priv_data;
+	struct fsl_mc_uapi *mc_uapi;
+	struct fsl_mc_io *mc_io;
+
+	priv_data = filep->private_data;
+	mc_uapi = priv_data->uapi;
+	mc_io = priv_data->mc_io;
+
+	mutex_lock(&mc_uapi->mutex);
+
+	if (mc_io == mc_uapi->static_mc_io)
+		mc_uapi->local_instance_in_use = 0;
+	else
+		fsl_mc_portal_free(mc_io);
+
+	kfree(filep->private_data);
+	filep->private_data =  NULL;
+
+	mutex_unlock(&mc_uapi->mutex);
+
+	return 0;
+}
+
+static long fsl_mc_uapi_dev_ioctl(struct file *file,
+				  unsigned int cmd,
+				  unsigned long arg)
+{
+	struct uapi_priv_data *priv_data = file->private_data;
+	struct fsl_mc_device *root_mc_device;
+	struct fsl_mc_bus *mc_bus;
+	int error;
+
+	mc_bus = container_of(priv_data->uapi, struct fsl_mc_bus, uapi_misc);
+	root_mc_device = &mc_bus->mc_dev;
+
+	switch (cmd) {
+	case FSL_MC_SEND_MC_COMMAND:
+		error = fsl_mc_uapi_send_command(arg, priv_data->mc_io);
+		break;
+	default:
+		dev_dbg(&root_mc_device->dev, "unexpected ioctl call number\n");
+		error = -EINVAL;
+	}
+
+	return error;
+}
+
+static const struct file_operations fsl_mc_uapi_dev_fops = {
+	.owner = THIS_MODULE,
+	.open = fsl_mc_uapi_dev_open,
+	.release = fsl_mc_uapi_dev_release,
+	.unlocked_ioctl = fsl_mc_uapi_dev_ioctl,
+};
+
+int fsl_mc_uapi_create_device_file(struct fsl_mc_bus *mc_bus)
+{
+	struct fsl_mc_device *mc_dev = &mc_bus->mc_dev;
+	struct fsl_mc_uapi *mc_uapi = &mc_bus->uapi_misc;
+	int error;
+
+	mc_uapi->misc.minor = MISC_DYNAMIC_MINOR;
+	mc_uapi->misc.name = dev_name(&mc_dev->dev);
+	mc_uapi->misc.fops = &fsl_mc_uapi_dev_fops;
+
+	error = misc_register(&mc_uapi->misc);
+	if (error)
+		return error;
+
+	mc_uapi->static_mc_io = mc_bus->mc_dev.mc_io;
+
+	mutex_init(&mc_uapi->mutex);
+
+	return 0;
+}
+
+void fsl_mc_uapi_remove_device_file(struct fsl_mc_bus *mc_bus)
+{
+	misc_deregister(&mc_bus->uapi_misc.misc);
+}

include/uapi/linux/fsl_mc.h

@@ -16,10 +16,19 @@
  * struct fsl_mc_command - Management Complex (MC) command structure
  * @header: MC command header
  * @params: MC command parameters
+ *
+ * Used by FSL_MC_SEND_MC_COMMAND
  */
 struct fsl_mc_command {
 	__le64 header;
 	__le64 params[MC_CMD_NUM_OF_PARAMS];
 };
 
+#define FSL_MC_SEND_CMD_IOCTL_TYPE	'R'
+#define FSL_MC_SEND_CMD_IOCTL_SEQ	0xE0
+
+#define FSL_MC_SEND_MC_COMMAND \
+	_IOWR(FSL_MC_SEND_CMD_IOCTL_TYPE, FSL_MC_SEND_CMD_IOCTL_SEQ, \
+	struct fsl_mc_command)
+
 #endif /* _UAPI_FSL_MC_H_ */