path: root/drivers/staging/dream/pmem.c

/* drivers/android/pmem.c
 *
 * Copyright (C) 2007 Google, Inc.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

#include <linux/miscdevice.h>
#include <linux/platform_device.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/list.h>
#include <linux/debugfs.h>
#include <linux/android_pmem.h>
#include <linux/mempolicy.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/cacheflush.h>

#define PMEM_MAX_DEVICES 10
#define PMEM_MAX_ORDER 128
#define PMEM_MIN_ALLOC PAGE_SIZE

#define PMEM_DEBUG 1

/* indicates that a refernce to this file has been taken via get_pmem_file,
 * the file should not be released until put_pmem_file is called */
#define PMEM_FLAGS_BUSY 0x1
/* indicates that this is a suballocation of a larger master range */
#define PMEM_FLAGS_CONNECTED (0x1 << 1)
/* indicates this is a master and not a sub allocation and that it is mmaped */
#define PMEM_FLAGS_MASTERMAP (0x1 << 2)
/* submap and unsubmap flags indicate:
 * 00: subregion has never been mmaped
 * 10: subregion has been mmaped, reference to the mm was taken
 * 11: subretion has ben released, refernece to the mm still held
 * 01: subretion has been released, reference to the mm has been released
 */
#define PMEM_FLAGS_SUBMAP (0x1 << 3)
#define PMEM_FLAGS_UNSUBMAP (0x1 << 4)


struct pmem_data {
	/* in alloc mode: an index into the bitmap
	 * in no_alloc mode: the size of the allocation */
	int index;
	/* see flags above for descriptions */
	unsigned int flags;
	/* protects this data field, if the mm_mmap sem will be held at the
	 * same time as this sem, the mm sem must be taken first (as this is
	 * the order for vma_open and vma_close ops */
	struct rw_semaphore sem;
	/* info about the mmaping process */
	struct vm_area_struct *vma;
	/* task struct of the mapping process */
	struct task_struct *task;
	/* process id of teh mapping process */
	pid_t pid;
	/* file descriptor of the master */
	int master_fd;
	/* file struct of the master */
	struct file *master_file;
	/* a list of currently available regions if this is a suballocation */
	struct list_head region_list;
	/* a linked list of data so we can access them for debugging */
	struct list_head list;
#if PMEM_DEBUG
	int ref;
#endif
};

struct pmem_bits {
	unsigned allocated:1;		/* 1 if allocated, 0 if free */
	unsigned order:7;		/* size of the region in pmem space */
};

struct pmem_region_node {
	struct pmem_region region;
	struct list_head list;
};

#define PMEM_DEBUG_MSGS 0
#if PMEM_DEBUG_MSGS
#define DLOG(fmt, args...) \
	do { printk(KERN_INFO "[%s:%s:%d] "fmt, __FILE__, __func__, __LINE__, \
		    ##args); } \
	while (0)
#else
#define DLOG(x...) do {} while (0)
#endif

struct pmem_info {
	struct miscdevice dev;
	/* physical start address of the remaped pmem space */
	unsigned long base;
	/* vitual start address of the remaped pmem space */
	unsigned char __iomem *vbase;
	/* total size of the pmem space */
	unsigned long size;
	/* number of entries in the pmem space */
	unsigned long num_entries;
	/* pfn of the garbage page in memory */
	unsigned long garbage_pfn;
	/* index of the garbage page in the pmem space */
	int garbage_index;
	/* the bitmap for the region indicating which entries are allocated
	 * and which are free */
	struct pmem_bits