/*
 * Remote Processor Framework
 *
 * Copyright(c) 2011 Texas Instruments, Inc.
 * Copyright(c) 2011 Google, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in
 *   the documentation and/or other materials provided with the
 *   distribution.
 * * Neither the name Texas Instruments nor the names of its
 *   contributors may be used to endorse or promote products derived
 *   from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef REMOTEPROC_H
#define REMOTEPROC_H

#include <linux/types.h>
#include <linux/kref.h>
#include <linux/klist.h>
#include <linux/mutex.h>
#include <linux/virtio.h>
#include <linux/completion.h>
#include <linux/idr.h>

/**
 * struct resource_table - firmware resource table header
 * @ver: version number
 * @num: number of resource entries
 * @reserved: reserved (must be zero)
 * @offset: array of offsets pointing at the various resource entries
 *
 * A resource table is essentially a list of system resources required
 * by the remote processor. It may also include configuration entries.
 * If needed, the remote processor firmware should contain this table
 * as a dedicated ".resource_table" ELF section.
 *
 * Some resources entries are mere announcements, where the host is informed
 * of specific remoteproc configuration. Other entries require the host to
 * do something (e.g. allocate a system resource). Sometimes a negotiation
 * is expected, where the firmware requests a resource, and once allocated,
 * the host should provide back its details (e.g. address of an allocated
 * memory region).
 *
 * The header of the resource table, as expressed by this structure,
 * contains a version number (should we need to change this format in the
 * future), the number of available resource entries, and their offsets
 * in the table.
 *
 * Immediately following this header are the resource entries themselves,
 * each of which begins with a resource entry header (as described below).
 */
struct resource_table {
	u32 ver;
	u32 num;
	u32 reserved[2];
	u32 offset[0];
} __packed;

/**
 * struct fw_rsc_hdr - firmware resource entry header
 * @type: resource type
 * @data: resource data
 *
 * Every resource entry begins with a 'struct fw_rsc_hdr' header providing
 * its @type. The content of the entry itself will immediately follow
 * this header, and it should be parsed according to the resource type.
 */
struct fw_rsc_hdr {
	u32 type;
	u8 data[0];
} __packed;

/**
 * enum fw_resource_type - types of resource entries
 *
 * @RSC_CARVEOUT:   request for allocation of a physically contiguous
 *		    memory region.
 * @RSC_DEVMEM:     request to iommu_map a memory-based peripheral.
 * @RSC_TRACE:	    announces the availability of a trace buffer into which
 *		    the remote processor will be writing logs.
 * @RSC_VDEV:       declare support for a virtio device, and serve as its
 *		    virtio header.
 * @RSC_LAST:       just keep this one at the end
 *
 * For more details regarding a specific resource type, please see its
 * dedicated structure below.
 *
 * Please note that these values are used as indices to the rproc_handle_rsc
 * lookup table, so please keep them sane. Moreover, @RSC_LAST is used to
 * check the validity of an index before the lookup table is accessed, so
 * please update it as needed.
 */
enum fw_resource_type {
	RSC_CARVEOUT	= 0,
	RSC_DEVMEM	= 1,
	RSC_TRACE	= 2,
	RSC_VDEV	= 3,
	RSC_LAST	= 4,
};

#define FW_RSC_ADDR_ANY (0xFFFFFFFFFFFFFFFF)

/**
 * struct fw_rsc_carveout - physically contiguous memory request
 * @da: device address
 * @pa: physical address
 * @len: length (in bytes)
 * @flags: iommu protection flags
 * @reserved: reserved (must be zero)
 * @name: human-readable name of the requested memory region
 *
 * This resource entry requests the host to allocate a physically contiguous
 * memory region.
 *
 * These request entries should precede other firmware resource entries,
 * as other entries might request placing other data objects inside
 * these memory regions (e.g. data/code segments, trace resource entries, ...).
 *
 * Allocating memory this way helps utilizing the reserved physical memory
 * (e.g. CMA) more efficiently, and also minimizes the number of TLB entries
 * needed to map it (in case @rproc is using an IOMMU). Reducing the TLB
 * pressure is important; it may have a substantial impact on performance.
 *
 * If the firmware is compiled with static addresses, then @da should specify
 * the expected device address of this memory region. If @da is set to
 * FW_RSC_ADDR_ANY, then the host will dynamically allocate it, and then
 * overwrite @da with the dynamically allocated address.
 *
 * We will always use @da to negotiate the device addresses, even if it
 * isn't using an iommu. In that case, though, it will obviously contain
 * physical addresses.
 *
 * Some remote processors needs to know the allocated physical address
 * even if they do use an iommu. This is needed, e.g., if they control
 * hardware accelerators which access the physical memory directly (this
 * is the case with OMAP4 for instance). In that case, the host will
 * overwrite @pa with the dynamically allocated physical address.
 * Generally we don't want to expose physical addresses if we don't have to
 * (remote processors are generally _not_ trusted), so we might want to
 * change this to happen _only_ when explicitly required by the hardware.
 *
 * @flags is used to provide IOMMU protection flags, and @name should
 * (optionally) contain a human readable name of this carveout region
 * (mainly for debugging purposes).
 */
struct fw_rsc_carveout {
	u32 da;
	u32 pa;
	u32 len;
	u32 flags;
	u32 reserved;
	u8 name[32];
} __packed;

/**
 * struct fw_rsc_devmem - iommu mapping request
 * @da: device address
 * @pa: physical address
 * @len: length (in bytes)
 * @flags: iommu protection flags
 * @reserved: reserved (must be zero)
 * @name: human-readable name of the requested region to be mapped
 *
 * This resource entry requests the host to iommu map a physically contiguous
 * memory region. This is needed in case the remote processor requires
 * access to certain memory-based peripherals; _never_ use it to access
 * regular memory.
 *
 * This is obviously only needed if the remote processor is accessing memory
 * via an iommu.
 *
 * @da should specify the required device address, @pa should specify
 * the physical address we want to map, @len should specify the size of
 * the mapping and @flags is the IOMMU protection flags. As always, @name may
 * (optionally) contain a human readable name of this mapping (mainly for
 * debugging purposes).
 *
 * Note: at this point we just "trust" those devmem entries to contain valid
 * physical addresses, but this isn't safe and will be changed: eventually we
 * want remoteproc implementations to provide us ranges of physical addresses
 * the firmware is allowed to request, and not allow firmwares to request
 * access to physical addresses that are outside those ranges.
 */
struct fw_rsc_devmem {
	u32 da;
	u32 pa;
	u32 len;
	u32 flags;
	u32 reserved;
	u8 name[32];
} __packed;

/**
 * struct fw_rsc_trace - trace buffer declaration
 * @da: device address
 * @len: length (in bytes)
 * @reserved: reserved (must be zero)
 * @name: human-readable name of the trace buffer
 *
 * This resource entry provides the host information about a trace buffer
 * into which the remote processor will write log messages.
 *
 * @da specifies the device address of the buffer, @len specifies
 * its size, and @name may contain a human readable name of the trace buffer.
 *
 * After booting the remote processor, the trace buffers are exposed to the
 * user via debugfs entries (called trace0, trace1, etc..).
 */
struct fw_rsc_trace {
	u32 da;
	u32 len;
	u32 reserved;
	u8 name[32];
} __packed;

/**
 * struct fw_rsc_vdev_vring - vring descriptor entry
 * @da: device address
 * @align: the alignment between the consumer and producer parts of the vring
 * @num: num of buffers supported by this vring (must be power of two)
 * @notifyid is a unique rproc-wide notify index for this vring. This notify
 * index is used when kicking a remote processor, to let it know that this
 * vring is triggered.
 * @reserved: reserved (must be zero)
 *
 * This descriptor is not a resource entry by itself; it is part of the
 * vdev resource type (see below).
 *
 * Note that @da should either contain the device address where
 * the remote processor is expecting the vring, or indicate that
 * dynamically allocation of the vring's device address is supported.
 */
struct fw_rsc_vdev_vring {
	u32 da;
	u32 align;
	u32 num;
	u32 notifyid;
	u32 reserved;
} __packed;

/**
 * struct fw_rsc_vdev - virtio device header
 * @id: virtio device id (as in virtio_ids.h)
 * @notifyid is a unique rproc-wide notify index for this vdev. This notify
 * index is used when kicking a remote processor, to let it know that the
 * status/features of this vdev have changes.
 * @dfeatures specifies the virtio device features supported by the firmware
 * @gfeatures is a place holder used by the host to write back the
 * negotiated features that are supported by both sides.
 * @config_len is the size of the virtio config space of this vdev. The config
 * space lies in the resource table immediate after this vdev header.
 * @status is a place holder where the host will indicate its virtio progress.
 * @num_of_vrings indicates how many vrings are described in this vdev header
 * @reserved: reserved (must be zero)
 * @vring is an array of @num_of_vrings entries of 'struct fw_rsc_vdev_vring'.
 *
 * This resource is a virtio device header: it provides information about
 * the vdev, and is then used by the host and its peer remote processors
 * to negotiate and share certain virtio properties.
 *
 * By providing this resource entry, the firmware essentially asks remoteproc
 * to statically allocate a vdev upon registration of the rproc (dynamic vdev
 * allocation is not yet supported).
 *
 * Note: unlike virtualization systems, the term 'host' here means
 * the Linux side which is running remoteproc to control the remote
 * processors. We use the name 'gfeatures' to comply with virtio's terms,
 * though there isn't really any virtualized guest OS here: it's the host
 * which is responsible for negotiating the final features.
 * Yeah, it's a bit confusing.
 *
 * Note: immediately following this structure is the virtio config space for
 * this vdev (which is specific to the vdev; for more info, read the virtio
 * spec). the size of the config space is specified by @config_len.
 */
struct fw_rsc_vdev {
	u32 id;
	u32 notifyid;
	u32 dfeatures;
	u32 gfeatures;
	u32 config_len;
	u8 status;
	u8 num_of_vrings;
	u8 reserved[2];
	struct fw_rsc_vdev_vring vring[0];
} __packed;

/**
 * struct rproc_mem_entry - memory entry descriptor
 * @va:	virtual address
 * @dma: dma address
 * @len: length, in bytes
 * @da: device address
 * @priv: associated data
 * @node: list node
 */
struct rproc_mem_entry {
	void *va;
	dma_addr_t dma;
	int len;
	u32 da;
	void *priv;
	struct list_head node;
};

struct rproc;

/**
 * struct rproc_ops - platform-specific device handlers
 * @start:	power on the device and boot it
 * @stop:	power off the device
 * @kick:	kick a virtqueue (virtqueue id given as a parameter)
 */
struct rproc_ops {
	int (*start)(struct rproc *rproc);
	int (*stop)(struct rproc *rproc);
	void (*kick)(struct rproc *rproc, int vqid);
};

/**
 * enum rproc_state - remote processor states
 * @RPROC_OFFLINE:	device is powered off
 * @RPROC_SUSPENDED:	device is suspended; needs to be woken up to receive
 *			a message.
 * @RPROC_RUNNING:	device is up and running
 * @RPROC_CRASHED:	device has crashed; need to start recovery
 * @RPROC_LAST:		just keep this one at the end
 *
 * Please note that the values of these states are used as indices
 * to rproc_state_string, a state-to-name lookup table,
 * so please keep the two synchronized. @RPROC_LAST is used to check
 * the validity of an index before the lookup table is accessed, so
 * please update it as needed too.
 */
enum rproc_state {
	RPROC_OFFLINE	= 0,
	RPROC_SUSPENDED	= 1,
	RPROC_RUNNING	= 2,
	RPROC_CRASHED	= 3,
	RPROC_LAST	= 4,
};

/**
 * struct rproc - represents a physical remote processor device
 * @node: klist node of this rproc object
 * @domain: iommu domain
 * @name: human readable name of the rproc
 * @firmware: name of firmware file to be loaded
 * @priv: private data which belongs to the platform-specific rproc module
 * @ops: platform-specific start/stop rproc handlers
 * @dev: underlying device
 * @refcount: refcount of users that have a valid pointer to this rproc
 * @power: refcount of users who need this rproc powered up
 * @state: state of the device
 * @lock: lock which protects concurrent manipulations of the rproc
 * @dbg_dir: debugfs directory of this rproc device
 * @traces: list of trace buffers
 * @num_traces: number of trace buffers
 * @carveouts: list of physically contiguous memory allocations
 * @mappings: list of iommu mappings we initiated, needed on shutdown
 * @firmware_loading_complete: marks e/o asynchronous firmware loading
 * @bootaddr: address of first instruction to boot rproc with (optional)
 * @rvdevs: list of remote virtio devices
 * @notifyids: idr for dynamically assigning rproc-wide unique notify ids
 */
struct rproc {
	struct klist_node node;
	struct iommu_domain *domain;
	const char *name;
	const char *firmware;
	void *priv;
	const struct rproc_ops *ops;
	struct device *dev;
	struct kref refcount;
	atomic_t power;
	unsigned int state;
	struct mutex lock;
	struct dentry *dbg_dir;
	struct list_head traces;
	int num_traces;
	struct list_head carveouts;
	struct list_head mappings;
	struct completion firmware_loading_complete;
	u32 bootaddr;
	struct list_head rvdevs;
	struct idr notifyids;
};

/* we currently support only two vrings per rvdev */
#define RVDEV_NUM_VRINGS 2

/**
 * struct rproc_vring - remoteproc vring state
 * @va:	virtual address
 * @dma: dma address
 * @len: length, in bytes
 * @da: device address
 * @align: vring alignment
 * @notifyid: rproc-specific unique vring index
 * @rvdev: remote vdev
 * @vq: the virtqueue of this vring
 */
struct rproc_vring {
	void *va;
	dma_addr_t dma;
	int len;
	u32 da;
	u32 align;
	int notifyid;
	struct rproc_vdev *rvdev;
	struct virtqueue *vq;
};

/**
 * struct rproc_vdev - remoteproc state for a supported virtio device
 * @node: list node
 * @rproc: the rproc handle
 * @vdev: the virio device
 * @vring: the vrings for this vdev
 * @dfeatures: virtio device features
 * @gfeatures: virtio guest features
 */
struct rproc_vdev {
	struct list_head node;
	struct rproc *rproc;
	struct virtio_device vdev;
	struct rproc_vring vring[RVDEV_NUM_VRINGS];
	unsigned long dfeatures;
	unsigned long gfeatures;
};

struct rproc *rproc_get_by_name(const char *name);
void rproc_put(struct rproc *rproc);

struct rproc *rproc_alloc(struct device *dev, const char *name,
				const struct rproc_ops *ops,
				const char *firmware, int len);
void rproc_free(struct rproc *rproc);
int rproc_register(struct rproc *rproc);
int rproc_unregister(struct rproc *rproc);

int rproc_boot(struct rproc *rproc);
void rproc_shutdown(struct rproc *rproc);

static inline struct rproc_vdev *vdev_to_rvdev(struct virtio_device *vdev)
{
	return container_of(vdev, struct rproc_vdev, vdev);
}

static inline struct rproc *vdev_to_rproc(struct virtio_device *vdev)
{
	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);

	return rvdev->rproc;
}

#endif /* REMOTEPROC_H */