include/linux/guest_shm.h

/*
 * Copyright 2018, QNX Software Systems Limited (“QSS”).
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/**
 * @file
 * definitions guest shared memory device
 */

#ifndef _QVM_GUEST_SHM_H
#define _QVM_GUEST_SHM_H

#ifdef __linux__
#include <linux/types.h>
#else
#include <stdint.h>
#endif

/*
 * Temporary VID definition until the updated <pci/pci_id.h> propogates around
 */
#define PCI_VID_BlackBerry_QNX	0x1C05

#define PCI_DID_QNX_GUEST_SHM	0x0001

/** status of last creation request */
enum guest_shm_status {
	GSS_OK,					/**< creation succeeded */
	GSS_UNKNOWN_FAILURE,	/**< creation failed for an unknown reason */
	GSS_NOMEM,				/**< creation failed due to lack of memory */
	GSS_CLIENT_MAX,			/**< creation failed due to region already being used by the maximum number of guests */
	GSS_ILLEGAL_NAME,		/**< creation failed due to illegal region name */
	GSS_NO_PERMISSION,		/**< creation failed due to lack of permission */
	GSS_DOES_NOT_EXIST,		/**< A find request failed */
};

/** Maximum number of clients allowed to connect to a shared memory region */
#define GUEST_SHM_MAX_CLIENTS	16

/** Maximum length allowed for region name */
#define GUEST_SHM_MAX_NAME	32

/** Signature value to verify that vdev is present */
#define GUEST_SHM_SIGNATURE 0x4d534732474d5651


/** Register layout for factory registers */
struct guest_shm_factory {
	uint64_t		signature; /**< == GUEST_SHM_SIGNATURE (R/O) */
	uint64_t		shmem;	/**< shared memory paddr (R/O) */
	uint32_t		vector;	/**< interrupt vector number (R/O) */
	uint32_t		status; /**< status of last creation (R/O) */
	uint32_t		size;	/**< requested size in 4K pages, write causes creation */
	char			name[GUEST_SHM_MAX_NAME];	/**< name of shared memory region */
	uint32_t		find;	/**< find an existing shared memory connection */
};

/** Register layout for a region control page */
struct guest_shm_control {
	uint32_t		status;	/**< lower 16 bits: pending notification bitset, upper 16 bits: current active clients (R/O) */
	uint32_t		idx;	/**< connection index for this client (R/O) */
	uint32_t		notify;	/**< write a bitset of clients to notify */
	uint32_t		detach; /**< write here to detach from the shared memory region */
};


static inline void
guest_shm_create(volatile struct guest_shm_factory *const __factory, unsigned const __size) {
	/* Surround the size assignment with memory barriers so that
	 * the compiler doesn't try to shift the assignment before/after
	 * necessary bits (e.g. setting the name of the region) */
	asm volatile( "" ::: "memory");
	__factory->size = __size;
	asm volatile( "" ::: "memory");
}


static inline void
guest_shm_find(volatile struct guest_shm_factory *const __factory, unsigned const __find_num) {
	/* Surround the find assignment with memory barriers so that
	 * the compiler doesn't try to shift the assignment before/after
	 * necessary bits (e.g. setting the name of the region) */
	asm volatile( "" ::: "memory");
	__factory->find = __find_num;
	asm volatile( "" ::: "memory");
}

#endif

#if defined(__QNXNTO__) && defined(__USESRCVERSION)
#include <sys/srcversion.h>
__SRCVERSION("$URL$ $Rev$")
#endif