Re: [patch] Re: newer version of HTC Dream support

[Pavel Machek]

This adds android pmem driver, one of dependencies of camera driver.

Signed-off-by: Pavel Machek <pavel@xxxxxx>

diff --git a/drivers/staging/dream/Kconfig b/drivers/staging/dream/Kconfig
index 5770ea6..67783f8 100644
--- a/drivers/staging/dream/Kconfig
+++ b/drivers/staging/dream/Kconfig
@@ -39,5 +39,9 @@ config INPUT_GPIO
 	  Say Y here if you want to support gpio based keys, wheels etc...
 
 config GENERIC_GPIO
-	bool
+	bool
+	default y
+
+config ANDROID_PMEM
+	bool "Android pmem allocator"
 	default y
diff --git a/drivers/staging/dream/Makefile b/drivers/staging/dream/Makefile
index 2b79151..6afbadf 100644
--- a/drivers/staging/dream/Makefile
+++ b/drivers/staging/dream/Makefile
@@ -1,4 +1,5 @@
 obj-$(CONFIG_MSM_ADSP)		+= qdsp5/ smd/
 obj-$(CONFIG_MSM_CAMERA)	+= camera/
 obj-$(CONFIG_INPUT_GPIO)	+= gpio_axis.o gpio_event.o gpio_input.o gpio_matrix.o gpio_output.o
+obj-$(CONFIG_ANDROID_PMEM)	+= pmem.o
 
diff --git a/drivers/staging/dream/pmem.c b/drivers/staging/dream/pmem.c
new file mode 100644
index 0000000..def6468
--- /dev/null
+++ b/drivers/staging/dream/pmem.c
@@ -0,0 +1,1335 @@
+/* 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 <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 *bitmap;
+	/* indicates the region should not be managed with an allocator */
+	unsigned no_allocator;
+	/* indicates maps of this region should be cached, if a mix of
+	 * cached and uncached is desired, set this and open the device with
+	 * O_SYNC to get an uncached region */
+	unsigned cached;
+	unsigned buffered;
+	/* in no_allocator mode the first mapper gets the whole space and sets
+	 * this flag */
+	unsigned allocated;
+	/* for debugging, creates a list of pmem file structs, the
+	 * data_list_sem should be taken before pmem_data->sem if both are
+	 * needed */
+	struct semaphore data_list_sem;
+	struct list_head data_list;
+	/* pmem_sem protects the bitmap array
+	 * a write lock should be held when modifying entries in bitmap
+	 * a read lock should be held when reading data from bits or
+	 * dereferencing a pointer into bitmap
+	 *
+	 * pmem_data->sem protects the pmem data of a particular file
+	 * Many of the function that require the pmem_data->sem have a non-
+	 * locking version for when the caller is already holding that sem.
+	 *
+	 * IF YOU TAKE BOTH LOCKS TAKE THEM IN THIS ORDER:
+	 * down(pmem_data->sem) => down(bitmap_sem)
+	 */
+	struct rw_semaphore bitmap_sem;
+
+	long (*ioctl)(struct file *, unsigned int, unsigned long);
+	int (*release)(struct inode *, struct file *);
+};
+
+static struct pmem_info pmem[PMEM_MAX_DEVICES];
+static int id_count;
+
+#define PMEM_IS_FREE(id, index) !(pmem[id].bitmap[index].allocated)
+#define PMEM_ORDER(id, index) pmem[id].bitmap[index].order
+#define PMEM_BUDDY_INDEX(id, index) (index ^ (1 << PMEM_ORDER(id, index)))
+#define PMEM_NEXT_INDEX(id, index) (index + (1 << PMEM_ORDER(id, index)))
+#define PMEM_OFFSET(index) (index * PMEM_MIN_ALLOC)
+#define PMEM_START_ADDR(id, index) (PMEM_OFFSET(index) + pmem[id].base)
+#define PMEM_LEN(id, index) ((1 << PMEM_ORDER(id, index)) * PMEM_MIN_ALLOC)
+#define PMEM_END_ADDR(id, index) (PMEM_START_ADDR(id, index) + \
+	PMEM_LEN(id, index))
+#define PMEM_START_VADDR(id, index) (PMEM_OFFSET(id, index) + pmem[id].vbase)
+#define PMEM_END_VADDR(id, index) (PMEM_START_VADDR(id, index) + \
+	PMEM_LEN(id, index))
+#define PMEM_REVOKED(data) (data->flags & PMEM_FLAGS_REVOKED)
+#define PMEM_IS_PAGE_ALIGNED(addr) (!((addr) & (~PAGE_MASK)))
+#define PMEM_IS_SUBMAP(data) ((data->flags & PMEM_FLAGS_SUBMAP) && \
+	(!(data->flags & PMEM_FLAGS_UNSUBMAP)))
+
+static int pmem_release(struct inode *, struct file *);
+static int pmem_mmap(struct file *, struct vm_area_struct *);
+static int pmem_open(struct inode *, struct file *);
+static long pmem_ioctl(struct file *, unsigned int, unsigned long);
+
+struct file_operations pmem_fops = {
+	.release = pmem_release,
+	.mmap = pmem_mmap,
+	.open = pmem_open,
+	.unlocked_ioctl = pmem_ioctl,
+};
+
+static int get_id(struct file *file)
+{
+	return MINOR(file->f_dentry->d_inode->i_rdev);
+}
+
+static int is_pmem_file(struct file *file)
+{
+	int id;
+
+	if (unlikely(!file || !file->f_dentry || !file->f_dentry->d_inode))
+		return 0;
+	id = get_id(file);
+	if (unlikely(id >= PMEM_MAX_DEVICES))
+		return 0;
+	if (unlikely(file->f_dentry->d_inode->i_rdev !=
+	     MKDEV(MISC_MAJOR, pmem[id].dev.minor)))
+		return 0;
+	return 1;
+}
+
+static int has_allocation(struct file *file)
+{
+	struct pmem_data *data;
+	/* check is_pmem_file first if not accessed via pmem_file_ops */
+
+	if (unlikely(!file->private_data))
+		return 0;
+	data = (struct pmem_data *)file->private_data;
+	if (unlikely(data->index < 0))
+		return 0;
+	return 1;
+}
+
+static int is_master_owner(struct file *file)
+{
+	struct file *master_file;
+	struct pmem_data *data;
+	int put_needed, ret = 0;
+
+	if (!is_pmem_file(file) || !has_allocation(file))
+		return 0;
+	data = (struct pmem_data *)file->private_data;
+	if (PMEM_FLAGS_MASTERMAP & data->flags)
+		return 1;
+	master_file = fget_light(data->master_fd, &put_needed);
+	if (master_file && data->master_file == master_file)
+		ret = 1;
+	fput_light(master_file, put_needed);
+	return ret;
+}
+
+static int pmem_free(int id, int index)
+{
+	/* caller should hold the write lock on pmem_sem! */
+	int buddy, curr = index;
+	DLOG("index %d\n", index);
+
+	if (pmem[id].no_allocator) {
+		pmem[id].allocated = 0;
+		return 0;
+	}
+	/* clean up the bitmap, merging any buddies */
+	pmem[id].bitmap[curr].allocated = 0;
+	/* find a slots buddy Buddy# = Slot# ^ (1 << order)
+	 * if the buddy is also free merge them
+	 * repeat until the buddy is not free or end of the bitmap is reached
+	 */
+	do {
+		buddy = PMEM_BUDDY_INDEX(id, curr);
+		if (PMEM_IS_FREE(id, buddy) &&
+				PMEM_ORDER(id, buddy) == PMEM_ORDER(id, curr)) {
+			PMEM_ORDER(id, buddy)++;
+			PMEM_ORDER(id, curr)++;
+			curr = min(buddy, curr);
+		} else {
+			break;
+		}
+	} while (curr < pmem[id].num_entries);
+
+	return 0;
+}
+
+static void pmem_revoke(struct file *file, struct pmem_data *data);
+
+static int pmem_release(struct inode *inode, struct file *file)
+{
+	struct pmem_data *data = (struct pmem_data *)file->private_data;
+	struct pmem_region_node *region_node;
+	struct list_head *elt, *elt2;
+	int id = get_id(file), ret = 0;
+
+
+	down(&pmem[id].data_list_sem);
+	/* if this file is a master, revoke all the memory in the connected
+	 *  files */
+	if (PMEM_FLAGS_MASTERMAP & data->flags) {
+		struct pmem_data *sub_data;
+		list_for_each(elt, &pmem[id].data_list) {
+			sub_data = list_entry(elt, struct pmem_data, list);
+			down_read(&sub_data->sem);
+			if (PMEM_IS_SUBMAP(sub_data) &&
+			    file == sub_data->master_file) {
+				up_read(&sub_data->sem);
+				pmem_revoke(file, sub_data);
+			}  else
+				up_read(&sub_data->sem);
+		}
+	}
+	list_del(&data->list);
+	up(&pmem[id].data_list_sem);
+
+
+	down_write(&data->sem);
+
+	/* if its not a conencted file and it has an allocation, free it */
+	if (!(PMEM_FLAGS_CONNECTED & data->flags) && has_allocation(file)) {
+		down_write(&pmem[id].bitmap_sem);
+		ret = pmem_free(id, data->index);
+		up_write(&pmem[id].bitmap_sem);
+	}
+
+	/* if this file is a submap (mapped, connected file), downref the
+	 * task struct */
+	if (PMEM_FLAGS_SUBMAP & data->flags)
+		if (data->task) {
+			put_task_struct(data->task);
+			data->task = NULL;
+		}
+
+	file->private_data = NULL;
+
+	list_for_each_safe(elt, elt2, &data->region_list) {
+		region_node = list_entry(elt, struct pmem_region_node, list);
+		list_del(elt);
+		kfree(region_node);
+	}
+	BUG_ON(!list_empty(&data->region_list));
+
+	up_write(&data->sem);
+	kfree(data);
+	if (pmem[id].release)
+		ret = pmem[id].release(inode, file);
+
+	return ret;
+}
+
+static int pmem_open(struct inode *inode, struct file *file)
+{
+	struct pmem_data *data;
+	int id = get_id(file);
+	int ret = 0;
+
+	DLOG("current %u file %p(%d)\n", current->pid, file, file_count(file));
+	/* setup file->private_data to indicate its unmapped */
+	/*  you can only open a pmem device one time */
+	if (file->private_data != NULL)
+		return -1;
+	data = kmalloc(sizeof(struct pmem_data), GFP_KERNEL);
+	if (!data) {
+		printk("pmem: unable to allocate memory for pmem metadata.");
+		return -1;
+	}
+	data->flags = 0;
+	data->index = -1;
+	data->task = NULL;
+	data->vma = NULL;
+	data->pid = 0;
+	data->master_file = NULL;
+#if PMEM_DEBUG
+	data->ref = 0;
+#endif
+	INIT_LIST_HEAD(&data->region_list);
+	init_rwsem(&data->sem);
+
+	file->private_data = data;
+	INIT_LIST_HEAD(&data->list);
+
+	down(&pmem[id].data_list_sem);
+	list_add(&data->list, &pmem[id].data_list);
+	up(&pmem[id].data_list_sem);
+	return ret;
+}
+
+static unsigned long pmem_order(unsigned long len)
+{
+	int i;
+
+	len = (len + PMEM_MIN_ALLOC - 1)/PMEM_MIN_ALLOC;
+	len--;
+	for (i = 0; i < sizeof(len)*8; i++)
+		if (len >> i == 0)
+			break;
+	return i;
+}
+
+static int pmem_allocate(int id, unsigned long len)
+{
+	/* caller should hold the write lock on pmem_sem! */
+	/* return the corresponding pdata[] entry */
+	int curr = 0;
+	int end = pmem[id].num_entries;
+	int best_fit = -1;
+	unsigned long order = pmem_order(len);
+
+	if (pmem[id].no_allocator) {
+		DLOG("no allocator");
+		if ((len > pmem[id].size) || pmem[id].allocated)
+			return -1;
+		pmem[id].allocated = 1;
+		return len;
+	}
+
+	if (order > PMEM_MAX_ORDER)
+		return -1;
+	DLOG("order %lx\n", order);
+
+	/* look through the bitmap:
+	 * 	if you find a free slot of the correct order use it
+	 * 	otherwise, use the best fit (smallest with size > order) slot
+	 */
+	while (curr < end) {
+		if (PMEM_IS_FREE(id, curr)) {
+			if (PMEM_ORDER(id, curr) == (unsigned char)order) {
+				/* set the not free bit and clear others */
+				best_fit = curr;
+				break;
+			}
+			if (PMEM_ORDER(id, curr) > (unsigned char)order &&
+			    (best_fit < 0 ||
+			     PMEM_ORDER(id, curr) < PMEM_ORDER(id, best_fit)))
+				best_fit = curr;
+		}
+		curr = PMEM_NEXT_INDEX(id, curr);
+	}
+
+	/* if best_fit < 0, there are no suitable slots,
+	 * return an error
+	 */
+	if (best_fit < 0) {
+		printk("pmem: no space left to allocate!\n");
+		return -1;
+	}
+
+	/* now partition the best fit:
+	 * 	split the slot into 2 buddies of order - 1
+	 * 	repeat until the slot is of the correct order
+	 */
+	while (PMEM_ORDER(id, best_fit) > (unsigned char)order) {
+		int buddy;
+		PMEM_ORDER(id, best_fit) -= 1;
+		buddy = PMEM_BUDDY_INDEX(id, best_fit);
+		PMEM_ORDER(id, buddy) = PMEM_ORDER(id, best_fit);
+	}
+	pmem[id].bitmap[best_fit].allocated = 1;
+	return best_fit;
+}
+
+static pgprot_t phys_mem_access_prot(struct file *file, pgprot_t vma_prot)
+{
+	int id = get_id(file);
+#ifdef pgprot_noncached
+	if (pmem[id].cached == 0 || file->f_flags & O_SYNC)
+		return pgprot_noncached(vma_prot);
+#endif
+#ifdef pgprot_ext_buffered
+	else if (pmem[id].buffered)
+		return pgprot_ext_buffered(vma_prot);
+#endif
+	return vma_prot;
+}
+
+static unsigned long pmem_start_addr(int id, struct pmem_data *data)
+{
+	if (pmem[id].no_allocator)
+		return PMEM_START_ADDR(id, 0);
+	else
+		return PMEM_START_ADDR(id, data->index);
+
+}
+
+static void *pmem_start_vaddr(int id, struct pmem_data *data)
+{
+	return pmem_start_addr(id, data) - pmem[id].base + pmem[id].vbase;
+}
+
+static unsigned long pmem_len(int id, struct pmem_data *data)
+{
+	if (pmem[id].no_allocator)
+		return data->index;
+	else
+		return PMEM_LEN(id, data->index);
+}
+
+static int pmem_map_garbage(int id, struct vm_area_struct *vma,
+			    struct pmem_data *data, unsigned long offset,
+			    unsigned long len)
+{
+	int i, garbage_pages = len >> PAGE_SHIFT;
+
+	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP | VM_SHARED | VM_WRITE;
+	for (i = 0; i < garbage_pages; i++) {
+		if (vm_insert_pfn(vma, vma->vm_start + offset + (i * PAGE_SIZE),
+		    pmem[id].garbage_pfn))
+			return -EAGAIN;
+	}
+	return 0;
+}
+
+static int pmem_unmap_pfn_range(int id, struct vm_area_struct *vma,
+				struct pmem_data *data, unsigned long offset,
+				unsigned long len)
+{
+	int garbage_pages;
+	DLOG("unmap offset %lx len %lx\n", offset, len);
+
+	BUG_ON(!PMEM_IS_PAGE_ALIGNED(len));
+
+	garbage_pages = len >> PAGE_SHIFT;
+	zap_page_range(vma, vma->vm_start + offset, len, NULL);
+	pmem_map_garbage(id, vma, data, offset, len);
+	return 0;
+}
+
+static int pmem_map_pfn_range(int id, struct vm_area_struct *vma,
+			      struct pmem_data *data, unsigned long offset,
+			      unsigned long len)
+{
+	DLOG("map offset %lx len %lx\n", offset, len);
+	BUG_ON(!PMEM_IS_PAGE_ALIGNED(vma->vm_start));
+	BUG_ON(!PMEM_IS_PAGE_ALIGNED(vma->vm_end));
+	BUG_ON(!PMEM_IS_PAGE_ALIGNED(len));
+	BUG_ON(!PMEM_IS_PAGE_ALIGNED(offset));
+
+	if (io_remap_pfn_range(vma, vma->vm_start + offset,
+		(pmem_start_addr(id, data) + offset) >> PAGE_SHIFT,
+		len, vma->vm_page_prot)) {
+		return -EAGAIN;
+	}
+	return 0;
+}
+
+static int pmem_remap_pfn_range(int id, struct vm_area_struct *vma,
+			      struct pmem_data *data, unsigned long offset,
+			      unsigned long len)
+{
+	/* hold the mm semp for the vma you are modifying when you call this */
+	BUG_ON(!vma);
+	zap_page_range(vma, vma->vm_start + offset, len, NULL);
+	return pmem_map_pfn_range(id, vma, data, offset, len);
+}
+
+static void pmem_vma_open(struct vm_area_struct *vma)
+{
+	struct file *file = vma->vm_file;
+	struct pmem_data *data = file->private_data;
+	int id = get_id(file);
+	/* this should never be called as we don't support copying pmem
+	 * ranges via fork */
+	BUG_ON(!has_allocation(file));
+	down_write(&data->sem);
+	/* remap the garbage pages, forkers don't get access to the data */
+	pmem_unmap_pfn_range(id, vma, data, 0, vma->vm_start - vma->vm_end);
+	up_write(&data->sem);
+}
+
+static void pmem_vma_close(struct vm_area_struct *vma)
+{
+	struct file *file = vma->vm_file;
+	struct pmem_data *data = file->private_data;
+
+	DLOG("current %u ppid %u file %p count %d\n", current->pid,
+	     current->parent->pid, file, file_count(file));
+	if (unlikely(!is_pmem_file(file) || !has_allocation(file))) {
+		printk(KERN_WARNING "pmem: something is very wrong, you are "
+		       "closing a vm backing an allocation that doesn't "
+		       "exist!\n");
+		return;
+	}
+	down_write(&data->sem);
+	if (data->vma == vma) {
+		data->vma = NULL;
+		if ((data->flags & PMEM_FLAGS_CONNECTED) &&
+		    (data->flags & PMEM_FLAGS_SUBMAP))
+			data->flags |= PMEM_FLAGS_UNSUBMAP;
+	}
+	/* the kernel is going to free this vma now anyway */
+	up_write(&data->sem);
+}
+
+static struct vm_operations_struct vm_ops = {
+	.open = pmem_vma_open,
+	.close = pmem_vma_close,
+};
+
+static int pmem_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct pmem_data *data;
+	int index;
+	unsigned long vma_size =  vma->vm_end - vma->vm_start;
+	int ret = 0, id = get_id(file);
+
+	if (vma->vm_pgoff || !PMEM_IS_PAGE_ALIGNED(vma_size)) {
+#if PMEM_DEBUG
+		printk(KERN_ERR "pmem: mmaps must be at offset zero, aligned"
+				" and a multiple of pages_size.\n");
+#endif
+		return -EINVAL;
+	}
+
+	data = (struct pmem_data *)file->private_data;
+	down_write(&data->sem);
+	/* check this file isn't already mmaped, for submaps check this file
+	 * has never been mmaped */
+	if ((data->flags & PMEM_FLAGS_MASTERMAP) ||
+	    (data->flags & PMEM_FLAGS_SUBMAP) ||
+	    (data->flags & PMEM_FLAGS_UNSUBMAP)) {
+#if PMEM_DEBUG
+		printk(KERN_ERR "pmem: you can only mmap a pmem file once, "
+		       "this file is already mmaped. %x\n", data->flags);
+#endif
+		ret = -EINVAL;
+		goto error;
+	}
+	/* if file->private_data == unalloced, alloc*/
+	if (data && data->index == -1) {
+		down_write(&pmem[id].bitmap_sem);
+		index = pmem_allocate(id, vma->vm_end - vma->vm_start);
+		up_write(&pmem[id].bitmap_sem);
+		data->index = index;
+	}
+	/* either no space was available or an error occured */
+	if (!has_allocation(file)) {
+		ret = -EINVAL;
+		printk("pmem: could not find allocation for map.\n");
+		goto error;
+	}
+
+	if (pmem_len(id, data) < vma_size) {
+#if PMEM_DEBUG
+		printk(KERN_WARNING "pmem: mmap size [%lu] does not match"
+		       "size of backing region [%lu].\n", vma_size,
+		       pmem_len(id, data));
+#endif
+		ret = -EINVAL;
+		goto error;
+	}
+
+	vma->vm_pgoff = pmem_start_addr(id, data) >> PAGE_SHIFT;
+	vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_page_prot);
+
+	if (data->flags & PMEM_FLAGS_CONNECTED) {
+		struct pmem_region_node *region_node;
+		struct list_head *elt;
+		if (pmem_map_garbage(id, vma, data, 0, vma_size)) {
+			printk("pmem: mmap failed in kernel!\n");
+			ret = -EAGAIN;
+			goto error;
+		}
+		list_for_each(elt, &data->region_list) {
+			region_node = list_entry(elt, struct pmem_region_node,
+						 list);
+			DLOG("remapping file: %p %lx %lx\n", file,
+				region_node->region.offset,
+				region_node->region.len);
+			if (pmem_remap_pfn_range(id, vma, data,
+						 region_node->region.offset,
+						 region_node->region.len)) {
+				ret = -EAGAIN;
+				goto error;
+			}
+		}
+		data->flags |= PMEM_FLAGS_SUBMAP;
+		get_task_struct(current->group_leader);
+		data->task = current->group_leader;
+		data->vma = vma;
+#if PMEM_DEBUG
+		data->pid = current->pid;
+#endif
+		DLOG("submmapped file %p vma %p pid %u\n", file, vma,
+		     current->pid);
+	} else {
+		if (pmem_map_pfn_range(id, vma, data, 0, vma_size)) {
+			printk(KERN_INFO "pmem: mmap failed in kernel!\n");
+			ret = -EAGAIN;
+			goto error;
+		}
+		data->flags |= PMEM_FLAGS_MASTERMAP;
+		data->pid = current->pid;
+	}
+	vma->vm_ops = &vm_ops;
+error:
+	up_write(&data->sem);
+	return ret;
+}
+
+/* the following are the api for accessing pmem regions by other drivers
+ * from inside the kernel */
+int get_pmem_user_addr(struct file *file, unsigned long *start,
+		   unsigned long *len)
+{
+	struct pmem_data *data;
+	if (!is_pmem_file(file) || !has_allocation(file)) {
+#if PMEM_DEBUG
+		printk(KERN_INFO "pmem: requested pmem data from invalid"
+				  "file.\n");
+#endif
+		return -1;
+	}
+	data = (struct pmem_data *)file->private_data;
+	down_read(&data->sem);
+	if (data->vma) {
+		*start = data->vma->vm_start;
+		*len = data->vma->vm_end - data->vma->vm_start;
+	} else {
+		*start = 0;
+		*len = 0;
+	}
+	up_read(&data->sem);
+	return 0;
+}
+
+int get_pmem_addr(struct file *file, unsigned long *start,
+		  unsigned long *vstart, unsigned long *len)
+{
+	struct pmem_data *data;
+	int id;
+
+	if (!is_pmem_file(file) || !has_allocation(file)) {
+		return -1;
+	}
+
+	data = (struct pmem_data *)file->private_data;
+	if (data->index == -1) {
+#if PMEM_DEBUG
+		printk(KERN_INFO "pmem: requested pmem data from file with no "
+		       "allocation.\n");
+		return -1;
+#endif
+	}
+	id = get_id(file);
+
+	down_read(&data->sem);
+	*start = pmem_start_addr(id, data);
+	*len = pmem_len(id, data);
+	*vstart = (unsigned long)pmem_start_vaddr(id, data);
+	up_read(&data->sem);
+#if PMEM_DEBUG
+	down_write(&data->sem);
+	data->ref++;
+	up_write(&data->sem);
+#endif
+	return 0;
+}
+
+int get_pmem_file(int fd, unsigned long *start, unsigned long *vstart,
+		  unsigned long *len, struct file **filp)
+{
+	struct file *file;
+
+	file = fget(fd);
+	if (unlikely(file == NULL)) {
+		printk(KERN_INFO "pmem: requested data from file descriptor "
+		       "that doesn't exist.");
+		return -1;
+	}
+
+	if (get_pmem_addr(file, start, vstart, len))
+		goto end;
+
+	if (filp)
+		*filp = file;
+	return 0;
+end:
+	fput(file);
+	return -1;
+}
+
+void put_pmem_file(struct file *file)
+{
+	struct pmem_data *data;
+	int id;
+
+	if (!is_pmem_file(file))
+		return;
+	id = get_id(file);
+	data = (struct pmem_data *)file->private_data;
+#if PMEM_DEBUG
+	down_write(&data->sem);
+	if (data->ref == 0) {
+		printk("pmem: pmem_put > pmem_get %s (pid %d)\n",
+		       pmem[id].dev.name, data->pid);
+		BUG();
+	}
+	data->ref--;
+	up_write(&data->sem);
+#endif
+	fput(file);
+}
+
+void flush_pmem_file(struct file *file, unsigned long offset, unsigned long len)
+{
+	struct pmem_data *data;
+	int id;
+	void *vaddr;
+	struct pmem_region_node *region_node;
+	struct list_head *elt;
+	void *flush_start, *flush_end;
+
+	if (!is_pmem_file(file) || !has_allocation(file)) {
+		return;
+	}
+
+	id = get_id(file);
+	data = (struct pmem_data *)file->private_data;
+	if (!pmem[id].cached)
+		return;
+
+	down_read(&data->sem);
+	vaddr = pmem_start_vaddr(id, data);
+	/* if this isn't a submmapped file, flush the whole thing */
+	if (unlikely(!(data->flags & PMEM_FLAGS_CONNECTED))) {
+		dmac_flush_range(vaddr, vaddr + pmem_len(id, data));
+		goto end;
+	}
+	/* otherwise, flush the region of the file we are drawing */
+	list_for_each(elt, &data->region_list) {
+		region_node = list_entry(elt, struct pmem_region_node, list);
+		if ((offset >= region_node->region.offset) &&
+		    ((offset + len) <= (region_node->region.offset +
+			region_node->region.len))) {
+			flush_start = vaddr + region_node->region.offset;
+			flush_end = flush_start + region_node->region.len;
+			dmac_flush_range(flush_start, flush_end);
+			break;
+		}
+	}
+end:
+	up_read(&data->sem);
+}
+
+static int pmem_connect(unsigned long connect, struct file *file)
+{
+	struct pmem_data *data = (struct pmem_data *)file->private_data;
+	struct pmem_data *src_data;
+	struct file *src_file;
+	int ret = 0, put_needed;
+
+	down_write(&data->sem);
+	/* retrieve the src file and check it is a pmem file with an alloc */
+	src_file = fget_light(connect, &put_needed);
+	DLOG("connect %p to %p\n", file, src_file);
+	if (!src_file) {
+		printk("pmem: src file not found!\n");
+		ret = -EINVAL;
+		goto err_no_file;
+	}
+	if (unlikely(!is_pmem_file(src_file) || !has_allocation(src_file))) {
+		printk(KERN_INFO "pmem: src file is not a pmem file or has no "
+		       "alloc!\n");
+		ret = -EINVAL;
+		goto err_bad_file;
+	}
+	src_data = (struct pmem_data *)src_file->private_data;
+
+	if (has_allocation(file) && (data->index != src_data->index)) {
+		printk("pmem: file is already mapped but doesn't match this"
+		       " src_file!\n");
+		ret = -EINVAL;
+		goto err_bad_file;
+	}
+	data->index = src_data->index;
+	data->flags |= PMEM_FLAGS_CONNECTED;
+	data->master_fd = connect;
+	data->master_file = src_file;
+
+err_bad_file:
+	fput_light(src_file, put_needed);
+err_no_file:
+	up_write(&data->sem);
+	return ret;
+}
+
+static void pmem_unlock_data_and_mm(struct pmem_data *data,
+				    struct mm_struct *mm)
+{
+	up_write(&data->sem);
+	if (mm != NULL) {
+		up_write(&mm->mmap_sem);
+		mmput(mm);
+	}
+}
+
+static int pmem_lock_data_and_mm(struct file *file, struct pmem_data *data,
+				 struct mm_struct **locked_mm)
+{
+	int ret = 0;
+	struct mm_struct *mm = NULL;
+	*locked_mm = NULL;
+lock_mm:
+	down_read(&data->sem);
+	if (PMEM_IS_SUBMAP(data)) {
+		mm = get_task_mm(data->task);
+		if (!mm) {
+#if PMEM_DEBUG
+			printk("pmem: can't remap task is gone!\n");
+#endif
+			up_read(&data->sem);
+			return -1;
+		}
+	}
+	up_read(&data->sem);
+
+	if (mm)
+		down_write(&mm->mmap_sem);
+
+	down_write(&data->sem);
+	/* check that the file didn't get mmaped before we could take the
+	 * data sem, this should be safe b/c you can only submap each file
+	 * once */
+	if (PMEM_IS_SUBMAP(data) && !mm) {
+		pmem_unlock_data_and_mm(data, mm);
+		up_write(&data->sem);
+		goto lock_mm;
+	}
+	/* now check that vma.mm is still there, it could have been
+	 * deleted by vma_close before we could get the data->sem */
+	if ((data->flags & PMEM_FLAGS_UNSUBMAP) && (mm != NULL)) {
+		/* might as well release this */
+		if (data->flags & PMEM_FLAGS_SUBMAP) {
+			put_task_struct(data->task);
+			data->task = NULL;
+			/* lower the submap flag to show the mm is gone */
+			data->flags &= ~(PMEM_FLAGS_SUBMAP);
+		}
+		pmem_unlock_data_and_mm(data, mm);
+		return -1;
+	}
+	*locked_mm = mm;
+	return ret;
+}
+
+int pmem_remap(struct pmem_region *region, struct file *file,
+		      unsigned operation)
+{
+	int ret;
+	struct pmem_region_node *region_node;
+	struct mm_struct *mm = NULL;
+	struct list_head *elt, *elt2;
+	int id = get_id(file);
+	struct pmem_data *data = (struct pmem_data *)file->private_data;
+
+	/* pmem region must be aligned on a page boundry */
+	if (unlikely(!PMEM_IS_PAGE_ALIGNED(region->offset) ||
+		 !PMEM_IS_PAGE_ALIGNED(region->len))) {
+#if PMEM_DEBUG
+		printk("pmem: request for unaligned pmem suballocation "
+		       "%lx %lx\n", region->offset, region->len);
+#endif
+		return -EINVAL;
+	}
+
+	/* if userspace requests a region of len 0, there's nothing to do */
+	if (region->len == 0)
+		return 0;
+
+	/* lock the mm and data */
+	ret = pmem_lock_data_and_mm(file, data, &mm);
+	if (ret)
+		return 0;
+
+	/* only the owner of the master file can remap the client fds
+	 * that back in it */
+	if (!is_master_owner(file)) {
+#if PMEM_DEBUG
+		printk("pmem: remap requested from non-master process\n");
+#endif
+		ret = -EINVAL;
+		goto err;
+	}
+
+	/* check that the requested range is within the src allocation */
+	if (unlikely((region->offset > pmem_len(id, data)) ||
+		     (region->len > pmem_len(id, data)) ||
+		     (region->offset + region->len > pmem_len(id, data)))) {
+#if PMEM_DEBUG
+		printk(KERN_INFO "pmem: suballoc doesn't fit in src_file!\n");
+#endif
+		ret = -EINVAL;
+		goto err;
+	}
+
+	if (operation == PMEM_MAP) {
+		region_node = kmalloc(sizeof(struct pmem_region_node),
+			      GFP_KERNEL);
+		if (!region_node) {
+			ret = -ENOMEM;
+#if PMEM_DEBUG
+			printk(KERN_INFO "No space to allocate metadata!");
+#endif
+			goto err;
+		}
+		region_node->region = *region;
+		list_add(&region_node->list, &data->region_list);
+	} else if (operation == PMEM_UNMAP) {
+		int found = 0;
+		list_for_each_safe(elt, elt2, &data->region_list) {
+			region_node = list_entry(elt, struct pmem_region_node,
+				      list);
+			if (region->len == 0 ||
+			    (region_node->region.offset == region->offset &&
+			    region_node->region.len == region->len)) {
+				list_del(elt);
+				kfree(region_node);
+				found = 1;
+			}
+		}
+		if (!found) {
+#if PMEM_DEBUG
+			printk("pmem: Unmap region does not map any mapped "
+				"region!");
+#endif
+			ret = -EINVAL;
+			goto err;
+		}
+	}
+
+	if (data->vma && PMEM_IS_SUBMAP(data)) {
+		if (operation == PMEM_MAP)
+			ret = pmem_remap_pfn_range(id, data->vma, data,
+						   region->offset, region->len);
+		else if (operation == PMEM_UNMAP)
+			ret = pmem_unmap_pfn_range(id, data->vma, data,
+						   region->offset, region->len);
+	}
+
+err:
+	pmem_unlock_data_and_mm(data, mm);
+	return ret;
+}
+
+static void pmem_revoke(struct file *file, struct pmem_data *data)
+{
+	struct pmem_region_node *region_node;
+	struct list_head *elt, *elt2;
+	struct mm_struct *mm = NULL;
+	int id = get_id(file);
+	int ret = 0;
+
+	data->master_file = NULL;
+	ret = pmem_lock_data_and_mm(file, data, &mm);
+	/* if lock_data_and_mm fails either the task that mapped the fd, or
+	 * the vma that mapped it have already gone away, nothing more
+	 * needs to be done */
+	if (ret)
+		return;
+	/* unmap everything */
+	/* delete the regions and region list nothing is mapped any more */
+	if (data->vma)
+		list_for_each_safe(elt, elt2, &data->region_list) {
+			region_node = list_entry(elt, struct pmem_region_node,
+						 list);
+			pmem_unmap_pfn_range(id, data->vma, data,
+					     region_node->region.offset,
+					     region_node->region.len);
+			list_del(elt);
+			kfree(region_node);
+	}
+	/* delete the master file */
+	pmem_unlock_data_and_mm(data, mm);
+}
+
+static void pmem_get_size(struct pmem_region *region, struct file *file)
+{
+	struct pmem_data *data = (struct pmem_data *)file->private_data;
+	int id = get_id(file);
+
+	if (!has_allocation(file)) {
+		region->offset = 0;
+		region->len = 0;
+		return;
+	} else {
+		region->offset = pmem_start_addr(id, data);
+		region->len = pmem_len(id, data);
+	}
+	DLOG("offset %lx len %lx\n", region->offset, region->len);
+}
+
+
+static long pmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct pmem_data *data;
+	int id = get_id(file);
+
+	switch (cmd) {
+	case PMEM_GET_PHYS:
+		{
+			struct pmem_region region;
+			DLOG("get_phys\n");
+			if (!has_allocation(file)) {
+				region.offset = 0;
+				region.len = 0;
+			} else {
+				data = (struct pmem_data *)file->private_data;
+				region.offset = pmem_start_addr(id, data);
+				region.len = pmem_len(id, data);
+			}
+			printk(KERN_INFO "pmem: request for physical address of pmem region "
+					"from process %d.\n", current->pid);
+			if (copy_to_user((void __user *)arg, &region,
+						sizeof(struct pmem_region)))
+				return -EFAULT;
+			break;
+		}
+	case PMEM_MAP:
+		{
+			struct pmem_region region;
+			if (copy_from_user(&region, (void __user *)arg,
+						sizeof(struct pmem_region)))
+				return -EFAULT;
+			data = (struct pmem_data *)file->private_data;
+			return pmem_remap(&region, file, PMEM_MAP);
+		}
+		break;
+	case PMEM_UNMAP:
+		{
+			struct pmem_region region;
+			if (copy_from_user(&region, (void __user *)arg,
+						sizeof(struct pmem_region)))
+				return -EFAULT;
+			data = (struct pmem_data *)file->private_data;
+			return pmem_remap(&region, file, PMEM_UNMAP);
+			break;
+		}
+	case PMEM_GET_SIZE:
+		{
+			struct pmem_region region;
+			DLOG("get_size\n");
+			pmem_get_size(&region, file);
+			if (copy_to_user((void __user *)arg, &region,
+						sizeof(struct pmem_region)))
+				return -EFAULT;
+			break;
+		}
+	case PMEM_GET_TOTAL_SIZE:
+		{
+			struct pmem_region region;
+			DLOG("get total size\n");
+			region.offset = 0;
+			get_id(file);
+			region.len = pmem[id].size;
+			if (copy_to_user((void __user *)arg, &region,
+						sizeof(struct pmem_region)))
+				return -EFAULT;
+			break;
+		}
+	case PMEM_ALLOCATE:
+		{
+			if (has_allocation(file))
+				return -EINVAL;
+			data = (struct pmem_data *)file->private_data;
+			data->index = pmem_allocate(id, arg);
+			break;
+		}
+	case PMEM_CONNECT:
+		DLOG("connect\n");
+		return pmem_connect(arg, file);
+		break;
+	default:
+		if (pmem[id].ioctl)
+			return pmem[id].ioctl(file, cmd, arg);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+#if PMEM_DEBUG
+static ssize_t debug_open(struct inode *inode, struct file *file)
+{
+	file->private_data = inode->i_private;
+	return 0;
+}
+
+static ssize_t debug_read(struct file *file, char __user *buf, size_t count,
+			  loff_t *ppos)
+{
+	struct list_head *elt, *elt2;
+	struct pmem_data *data;
+	struct pmem_region_node *region_node;
+	int id = (int)file->private_data;
+	const int debug_bufmax = 4096;
+	static char buffer[4096];
+	int n = 0;
+
+	DLOG("debug open\n");
+	n = scnprintf(buffer, debug_bufmax,
+		      "pid #: mapped regions (offset, len) (offset,len)...\n");
+
+	down(&pmem[id].data_list_sem);
+	list_for_each(elt, &pmem[id].data_list) {
+		data = list_entry(elt, struct pmem_data, list);
+		down_read(&data->sem);
+		n += scnprintf(buffer + n, debug_bufmax - n, "pid %u:",
+				data->pid);
+		list_for_each(elt2, &data->region_list) {
+			region_node = list_entry(elt2, struct pmem_region_node,
+				      list);
+			n += scnprintf(buffer + n, debug_bufmax - n,
+					"(%lx,%lx) ",
+					region_node->region.offset,
+					region_node->region.len);
+		}
+		n += scnprintf(buffer + n, debug_bufmax - n, "\n");
+		up_read(&data->sem);
+	}
+	up(&pmem[id].data_list_sem);
+
+	n++;
+	buffer[n] = 0;
+	return simple_read_from_buffer(buf, count, ppos, buffer, n);
+}
+
+static struct file_operations debug_fops = {
+	.read = debug_read,
+	.open = debug_open,
+};
+#endif
+
+#if 0
+static struct miscdevice pmem_dev = {
+	.name = "pmem",
+	.fops = &pmem_fops,
+};
+#endif
+
+int pmem_setup(struct android_pmem_platform_data *pdata,
+	       long (*ioctl)(struct file *, unsigned int, unsigned long),
+	       int (*release)(struct inode *, struct file *))
+{
+	int err = 0;
+	int i, index = 0;
+	int id = id_count;
+	id_count++;
+
+	pmem[id].no_allocator = pdata->no_allocator;
+	pmem[id].cached = pdata->cached;
+	pmem[id].buffered = pdata->buffered;
+	pmem[id].base = pdata->start;
+	pmem[id].size = pdata->size;
+	pmem[id].ioctl = ioctl;
+	pmem[id].release = release;
+	init_rwsem(&pmem[id].bitmap_sem);
+	init_MUTEX(&pmem[id].data_list_sem);
+	INIT_LIST_HEAD(&pmem[id].data_list);
+	pmem[id].dev.name = pdata->name;
+	pmem[id].dev.minor = id;
+	pmem[id].dev.fops = &pmem_fops;
+	printk(KERN_INFO "%s: %d init\n", pdata->name, pdata->cached);
+
+	err = misc_register(&pmem[id].dev);
+	if (err) {
+		printk(KERN_ALERT "Unable to register pmem driver!\n");
+		goto err_cant_register_device;
+	}
+	pmem[id].num_entries = pmem[id].size / PMEM_MIN_ALLOC;
+
+	pmem[id].bitmap = kmalloc(pmem[id].num_entries *
+				  sizeof(struct pmem_bits), GFP_KERNEL);
+	if (!pmem[id].bitmap)
+		goto err_no_mem_for_metadata;
+
+	memset(pmem[id].bitmap, 0, sizeof(struct pmem_bits) *
+					  pmem[id].num_entries);
+
+	for (i = sizeof(pmem[id].num_entries) * 8 - 1; i >= 0; i--) {
+		if ((pmem[id].num_entries) &  1<<i) {
+			PMEM_ORDER(id, index) = i;
+			index = PMEM_NEXT_INDEX(id, index);
+		}
+	}
+
+	if (pmem[id].cached)
+		pmem[id].vbase = ioremap_cached(pmem[id].base,
+						pmem[id].size);
+#ifdef ioremap_ext_buffered
+	else if (pmem[id].buffered)
+		pmem[id].vbase = ioremap_ext_buffered(pmem[id].base,
+						      pmem[id].size);
+#endif
+	else
+		pmem[id].vbase = ioremap(pmem[id].base, pmem[id].size);
+
+	if (pmem[id].vbase == 0)
+		goto error_cant_remap;
+
+	pmem[id].garbage_pfn = page_to_pfn(alloc_page(GFP_KERNEL));
+	if (pmem[id].no_allocator)
+		pmem[id].allocated = 0;
+
+#if PMEM_DEBUG
+	debugfs_create_file(pdata->name, S_IFREG | S_IRUGO, NULL, (void *)id,
+			    &debug_fops);
+#endif
+	return 0;
+error_cant_remap:
+	kfree(pmem[id].bitmap);
+err_no_mem_for_metadata:
+	misc_deregister(&pmem[id].dev);
+err_cant_register_device:
+	return -1;
+}
+
+static int pmem_probe(struct platform_device *pdev)
+{
+	struct android_pmem_platform_data *pdata;
+
+	if (!pdev || !pdev->dev.platform_data) {
+		printk(KERN_ALERT "Unable to probe pmem!\n");
+		return -1;
+	}
+	pdata = pdev->dev.platform_data;
+	return pmem_setup(pdata, NULL, NULL);
+}
+
+
+static int pmem_remove(struct platform_device *pdev)
+{
+	int id = pdev->id;
+	__free_page(pfn_to_page(pmem[id].garbage_pfn));
+	misc_deregister(&pmem[id].dev);
+	return 0;
+}
+
+static struct platform_driver pmem_driver = {
+	.probe = pmem_probe,
+	.remove = pmem_remove,
+	.driver = { .name = "android_pmem" }
+};
+
+
+static int __init pmem_init(void)
+{
+	return platform_driver_register(&pmem_driver);
+}
+
+static void __exit pmem_exit(void)
+{
+	platform_driver_unregister(&pmem_driver);
+}
+
+module_init(pmem_init);
+module_exit(pmem_exit);
+

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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