mtd/ps3vram: Add ps3vram driver for accessing video RAM as MTD

Add ps3vram driver, which exposes unused video RAM on the PS3 as a MTD
device suitable for storage or swap.  Fast data transfer is achieved
using a local cache in system RAM and DMA transfers via the GPU.

Signed-off-by: Vivien Chappelier <vivien.chappelier@free.fr>
Signed-off-by: Jim Paris <jim@jtan.com>
Acked-by: Geoff Levand <geoffrey.levand@am.sony.com>
Acked-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

MAINTAINERS

@@ -3484,6 +3484,12 @@ L:	linuxppc-dev@ozlabs.org
 L:	cbe-oss-dev@ozlabs.org
 S:	Supported
 
+PS3VRAM DRIVER
+P:	Jim Paris
+M:	jim@jtan.com
+L:	cbe-oss-dev@ozlabs.org
+S:	Maintained
+
 PVRUSB2 VIDEO4LINUX DRIVER
 P:	Mike Isely
 M:	isely@pobox.com

arch/powerpc/include/asm/ps3.h

@@ -320,6 +320,7 @@ enum ps3_match_id {
 
 enum ps3_match_sub_id {
 	PS3_MATCH_SUB_ID_GPU_FB		= 1,
+	PS3_MATCH_SUB_ID_GPU_RAMDISK	= 2,
 };
 
 #define PS3_MODULE_ALIAS_EHCI		"ps3:1:0"

arch/powerpc/platforms/ps3/device-init.c

@@ -518,6 +518,41 @@ fail_device_register:
 	return result;
 }
 
+static int __init ps3_register_ramdisk_device(void)
+{
+	int result;
+	struct layout {
+		struct ps3_system_bus_device dev;
+	} *p;
+
+	pr_debug(" -> %s:%d\n", __func__, __LINE__);
+
+	p = kzalloc(sizeof(struct layout), GFP_KERNEL);
+
+	if (!p)
+		return -ENOMEM;
+
+	p->dev.match_id = PS3_MATCH_ID_GPU;
+	p->dev.match_sub_id = PS3_MATCH_SUB_ID_GPU_RAMDISK;
+	p->dev.dev_type = PS3_DEVICE_TYPE_IOC0;
+
+	result = ps3_system_bus_device_register(&p->dev);
+
+	if (result) {
+		pr_debug("%s:%d ps3_system_bus_device_register failed\n",
+			__func__, __LINE__);
+		goto fail_device_register;
+	}
+
+	pr_debug(" <- %s:%d\n", __func__, __LINE__);
+	return 0;
+
+fail_device_register:
+	kfree(p);
+	pr_debug(" <- %s:%d failed\n", __func__, __LINE__);
+	return result;
+}
+
 /**
  * ps3_setup_dynamic_device - Setup a dynamic device from the repository
  */
@@ -946,6 +981,8 @@ static int __init ps3_register_devices(void)
 
 	ps3_register_lpm_devices();
 
+	ps3_register_ramdisk_device();
+
 	pr_debug(" <- %s:%d\n", __func__, __LINE__);
 	return 0;
 }

drivers/mtd/devices/Kconfig

@@ -120,6 +120,13 @@ config MTD_PHRAM
 	  doesn't have access to, memory beyond the mem=xxx limit, nvram,
 	  memory on the video card, etc...
 
+config MTD_PS3VRAM
+	tristate "PS3 video RAM"
+	depends on FB_PS3
+	help
+	  This driver allows you to use excess PS3 video RAM as volatile
+	  storage or system swap.
+
 config MTD_LART
 	tristate "28F160xx flash driver for LART"
 	depends on SA1100_LART

drivers/mtd/devices/Makefile

@@ -16,3 +16,4 @@ obj-$(CONFIG_MTD_LART)		+= lart.o
 obj-$(CONFIG_MTD_BLOCK2MTD)	+= block2mtd.o
 obj-$(CONFIG_MTD_DATAFLASH)	+= mtd_dataflash.o
 obj-$(CONFIG_MTD_M25P80)	+= m25p80.o
+obj-$(CONFIG_MTD_PS3VRAM)	+= ps3vram.o

drivers/mtd/devices/ps3vram.c

@@ -0,0 +1,776 @@
+/**
+ * ps3vram - Use extra PS3 video ram as MTD block device.
+ *
+ * Copyright (c) 2007-2008 Jim Paris <jim@jtan.com>
+ * Added support RSX DMA Vivien Chappelier <vivien.chappelier@free.fr>
+ */
+
+#include <linux/io.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/slab.h>
+#include <linux/version.h>
+#include <linux/gfp.h>
+#include <linux/delay.h>
+#include <linux/mtd/mtd.h>
+
+#include <asm/lv1call.h>
+#include <asm/ps3.h>
+
+#define DEVICE_NAME		"ps3vram"
+
+#define XDR_BUF_SIZE (2 * 1024 * 1024) /* XDR buffer (must be 1MiB aligned) */
+#define XDR_IOIF 0x0c000000
+
+#define FIFO_BASE XDR_IOIF
+#define FIFO_SIZE (64 * 1024)
+
+#define DMA_PAGE_SIZE (4 * 1024)
+
+#define CACHE_PAGE_SIZE (256 * 1024)
+#define CACHE_PAGE_COUNT ((XDR_BUF_SIZE - FIFO_SIZE) / CACHE_PAGE_SIZE)
+
+#define CACHE_OFFSET CACHE_PAGE_SIZE
+#define FIFO_OFFSET 0
+
+#define CTRL_PUT 0x10
+#define CTRL_GET 0x11
+#define CTRL_TOP 0x15
+
+#define UPLOAD_SUBCH	1
+#define DOWNLOAD_SUBCH	2
+
+#define NV_MEMORY_TO_MEMORY_FORMAT_OFFSET_IN	0x0000030c
+#define NV_MEMORY_TO_MEMORY_FORMAT_NOTIFY	0x00000104
+
+#define L1GPU_CONTEXT_ATTRIBUTE_FB_BLIT 0x601
+
+struct mtd_info ps3vram_mtd;
+
+#define CACHE_PAGE_PRESENT 1
+#define CACHE_PAGE_DIRTY   2
+
+#define dbg(fmt, args...)	\
+	pr_debug("%s:%d " fmt "\n", __func__, __LINE__, ## args)
+
+struct ps3vram_tag {
+	unsigned int address;
+	unsigned int flags;
+};
+
+struct ps3vram_cache {
+	unsigned int page_count;
+	unsigned int page_size;
+	struct ps3vram_tag *tags;
+};
+
+struct ps3vram_priv {
+	uint64_t memory_handle;
+	uint64_t context_handle;
+	uint8_t *base;
+	uint32_t *ctrl;
+	uint32_t *reports;
+	uint8_t *xdr_buf;
+
+	uint32_t *fifo_base;
+	uint32_t *fifo_ptr;
+
+	struct ps3vram_cache cache;
+
+	/* Used to serialize cache/DMA operations */
+	struct mutex lock;
+};
+
+#define DMA_NOTIFIER_HANDLE_BASE 0x66604200 /* first DMA notifier handle */
+#define DMA_NOTIFIER_OFFSET_BASE 0x1000     /* first DMA notifier offset */
+#define DMA_NOTIFIER_SIZE        0x40
+
+#define NUM_NOTIFIERS		16
+
+#define NOTIFIER 7	/* notifier used for completion report */
+
+/* A trailing '-' means to subtract off ps3fb_videomemory.size */
+char *size = "256M-";
+module_param(size, charp, 0);
+MODULE_PARM_DESC(size, "memory size");
+
+static inline uint32_t *ps3vram_get_notifier(uint32_t *reports, int notifier)
+{
+	return (void *) reports +
+		DMA_NOTIFIER_OFFSET_BASE +
+		DMA_NOTIFIER_SIZE * notifier;
+}
+
+static void ps3vram_notifier_reset(struct mtd_info *mtd)
+{
+	int i;
+	struct ps3vram_priv *priv = mtd->priv;
+	uint32_t *notify = ps3vram_get_notifier(priv->reports, NOTIFIER);
+	for (i = 0; i < 4; i++)
+		notify[i] = 0xffffffff;
+}
+
+static int ps3vram_notifier_wait(struct mtd_info *mtd, int timeout_ms)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+	uint32_t *notify = ps3vram_get_notifier(priv->reports, NOTIFIER);
+
+	timeout_ms *= 1000;
+
+	do {
+		if (notify[3] == 0)
+			return 0;
+
+		if (timeout_ms)
+			udelay(1);
+	} while (timeout_ms--);
+
+	return -1;
+}
+
+static void ps3vram_dump_ring(struct mtd_info *mtd)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+	uint32_t *fifo;
+
+	pr_info("PUT = %08x GET = %08x\n", priv->ctrl[CTRL_PUT],
+		priv->ctrl[CTRL_GET]);
+	for (fifo = priv->fifo_base; fifo < priv->fifo_ptr; fifo++)
+		pr_info("%p: %08x\n", fifo, *fifo);
+}
+
+static void ps3vram_dump_reports(struct mtd_info *mtd)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+	int i;
+
+	for (i = 0; i < NUM_NOTIFIERS; i++) {
+		uint32_t *n = ps3vram_get_notifier(priv->reports, i);
+		pr_info("%p: %08x\n", n, *n);
+	}
+}
+
+static void ps3vram_init_ring(struct mtd_info *mtd)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+
+	priv->ctrl[CTRL_PUT] = FIFO_BASE + FIFO_OFFSET;
+	priv->ctrl[CTRL_GET] = FIFO_BASE + FIFO_OFFSET;
+}
+
+static int ps3vram_wait_ring(struct mtd_info *mtd, int timeout)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+
+	/* wait until setup commands are processed */
+	timeout *= 1000;
+	while (--timeout) {
+		if (priv->ctrl[CTRL_PUT] == priv->ctrl[CTRL_GET])
+			break;
+		udelay(1);
+	}
+	if (timeout == 0) {
+		pr_err("FIFO timeout (%08x/%08x/%08x)\n", priv->ctrl[CTRL_PUT],
+		       priv->ctrl[CTRL_GET], priv->ctrl[CTRL_TOP]);
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+static inline void ps3vram_out_ring(struct ps3vram_priv *priv, uint32_t data)
+{
+	*(priv->fifo_ptr)++ = data;
+}
+
+static inline void ps3vram_begin_ring(struct ps3vram_priv *priv, uint32_t chan,
+				      uint32_t tag, uint32_t size)
+{
+	ps3vram_out_ring(priv, (size << 18) | (chan << 13) | tag);
+}
+
+static void ps3vram_rewind_ring(struct mtd_info *mtd)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+	u64 status;
+
+	ps3vram_out_ring(priv, 0x20000000 | (FIFO_BASE + FIFO_OFFSET));
+
+	priv->ctrl[CTRL_PUT] = FIFO_BASE + FIFO_OFFSET;
+
+	/* asking the HV for a blit will kick the fifo */
+	status = lv1_gpu_context_attribute(priv->context_handle,
+					   L1GPU_CONTEXT_ATTRIBUTE_FB_BLIT,
+					   0, 0, 0, 0);
+	if (status)
+		pr_err("ps3vram: lv1_gpu_context_attribute FB_BLIT failed\n");
+
+	priv->fifo_ptr = priv->fifo_base;
+}
+
+static void ps3vram_fire_ring(struct mtd_info *mtd)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+	u64 status;
+
+	mutex_lock(&ps3_gpu_mutex);
+
+	priv->ctrl[CTRL_PUT] = FIFO_BASE + FIFO_OFFSET +
+		(priv->fifo_ptr - priv->fifo_base) * sizeof(uint32_t);
+
+	/* asking the HV for a blit will kick the fifo */
+	status = lv1_gpu_context_attribute(priv->context_handle,
+					   L1GPU_CONTEXT_ATTRIBUTE_FB_BLIT,
+					   0, 0, 0, 0);
+	if (status)
+		pr_err("ps3vram: lv1_gpu_context_attribute FB_BLIT failed\n");
+
+	if ((priv->fifo_ptr - priv->fifo_base) * sizeof(uint32_t) >
+	    FIFO_SIZE - 1024) {
+		dbg("fifo full, rewinding");
+		ps3vram_wait_ring(mtd, 200);
+		ps3vram_rewind_ring(mtd);
+	}
+
+	mutex_unlock(&ps3_gpu_mutex);
+}
+
+static void ps3vram_bind(struct mtd_info *mtd)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+
+	ps3vram_begin_ring(priv, UPLOAD_SUBCH, 0, 1);
+	ps3vram_out_ring(priv, 0x31337303);
+	ps3vram_begin_ring(priv, UPLOAD_SUBCH, 0x180, 3);
+	ps3vram_out_ring(priv, DMA_NOTIFIER_HANDLE_BASE + NOTIFIER);
+	ps3vram_out_ring(priv, 0xfeed0001);	/* DMA system RAM instance */
+	ps3vram_out_ring(priv, 0xfeed0000);     /* DMA video RAM instance */
+
+	ps3vram_begin_ring(priv, DOWNLOAD_SUBCH, 0, 1);
+	ps3vram_out_ring(priv, 0x3137c0de);
+	ps3vram_begin_ring(priv, DOWNLOAD_SUBCH, 0x180, 3);
+	ps3vram_out_ring(priv, DMA_NOTIFIER_HANDLE_BASE + NOTIFIER);
+	ps3vram_out_ring(priv, 0xfeed0000);	/* DMA video RAM instance */
+	ps3vram_out_ring(priv, 0xfeed0001);	/* DMA system RAM instance */
+
+	ps3vram_fire_ring(mtd);
+}
+
+static int ps3vram_upload(struct mtd_info *mtd, unsigned int src_offset,
+			  unsigned int dst_offset, int len, int count)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+
+	ps3vram_begin_ring(priv, UPLOAD_SUBCH,
+			   NV_MEMORY_TO_MEMORY_FORMAT_OFFSET_IN, 8);
+	ps3vram_out_ring(priv, XDR_IOIF + src_offset);
+	ps3vram_out_ring(priv, dst_offset);
+	ps3vram_out_ring(priv, len);
+	ps3vram_out_ring(priv, len);
+	ps3vram_out_ring(priv, len);
+	ps3vram_out_ring(priv, count);
+	ps3vram_out_ring(priv, (1 << 8) | 1);
+	ps3vram_out_ring(priv, 0);
+
+	ps3vram_notifier_reset(mtd);
+	ps3vram_begin_ring(priv, UPLOAD_SUBCH,
+			   NV_MEMORY_TO_MEMORY_FORMAT_NOTIFY, 1);
+	ps3vram_out_ring(priv, 0);
+	ps3vram_begin_ring(priv, UPLOAD_SUBCH, 0x100, 1);
+	ps3vram_out_ring(priv, 0);
+	ps3vram_fire_ring(mtd);
+	if (ps3vram_notifier_wait(mtd, 200) < 0) {
+		pr_err("notifier timeout\n");
+		ps3vram_dump_ring(mtd);
+		ps3vram_dump_reports(mtd);
+		return -1;
+	}
+
+	return 0;
+}
+
+static int ps3vram_download(struct mtd_info *mtd, unsigned int src_offset,
+			    unsigned int dst_offset, int len, int count)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+
+	ps3vram_begin_ring(priv, DOWNLOAD_SUBCH,
+			   NV_MEMORY_TO_MEMORY_FORMAT_OFFSET_IN, 8);
+	ps3vram_out_ring(priv, src_offset);
+	ps3vram_out_ring(priv, XDR_IOIF + dst_offset);
+	ps3vram_out_ring(priv, len);
+	ps3vram_out_ring(priv, len);
+	ps3vram_out_ring(priv, len);
+	ps3vram_out_ring(priv, count);
+	ps3vram_out_ring(priv, (1 << 8) | 1);
+	ps3vram_out_ring(priv, 0);
+
+	ps3vram_notifier_reset(mtd);
+	ps3vram_begin_ring(priv, DOWNLOAD_SUBCH,
+			   NV_MEMORY_TO_MEMORY_FORMAT_NOTIFY, 1);
+	ps3vram_out_ring(priv, 0);
+	ps3vram_begin_ring(priv, DOWNLOAD_SUBCH, 0x100, 1);
+	ps3vram_out_ring(priv, 0);
+	ps3vram_fire_ring(mtd);
+	if (ps3vram_notifier_wait(mtd, 200) < 0) {
+		pr_err("notifier timeout\n");
+		ps3vram_dump_ring(mtd);
+		ps3vram_dump_reports(mtd);
+		return -1;
+	}
+
+	return 0;
+}
+
+static void ps3vram_cache_evict(struct mtd_info *mtd, int entry)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+	struct ps3vram_cache *cache = &priv->cache;
+
+	if (cache->tags[entry].flags & CACHE_PAGE_DIRTY) {
+		dbg("flushing %d : 0x%08x", entry, cache->tags[entry].address);
+		if (ps3vram_upload(mtd,
+				   CACHE_OFFSET + entry * cache->page_size,
+				   cache->tags[entry].address,
+				   DMA_PAGE_SIZE,
+				   cache->page_size / DMA_PAGE_SIZE) < 0) {
+			pr_err("failed to upload from 0x%x to 0x%x size 0x%x\n",
+			       entry * cache->page_size,
+			       cache->tags[entry].address,
+			       cache->page_size);
+		}
+		cache->tags[entry].flags &= ~CACHE_PAGE_DIRTY;
+	}
+}
+
+static void ps3vram_cache_load(struct mtd_info *mtd, int entry,
+			       unsigned int address)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+	struct ps3vram_cache *cache = &priv->cache;
+
+	dbg("fetching %d : 0x%08x", entry, address);
+	if (ps3vram_download(mtd,
+			     address,
+			     CACHE_OFFSET + entry * cache->page_size,
+			     DMA_PAGE_SIZE,
+			     cache->page_size / DMA_PAGE_SIZE) < 0) {
+		pr_err("failed to download from 0x%x to 0x%x size 0x%x\n",
+		       address,
+		       entry * cache->page_size,
+		       cache->page_size);
+	}
+
+	cache->tags[entry].address = address;
+	cache->tags[entry].flags |= CACHE_PAGE_PRESENT;
+}
+
+
+static void ps3vram_cache_flush(struct mtd_info *mtd)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+	struct ps3vram_cache *cache = &priv->cache;
+	int i;
+
+	dbg("FLUSH");
+	for (i = 0; i < cache->page_count; i++) {
+		ps3vram_cache_evict(mtd, i);
+		cache->tags[i].flags = 0;
+	}
+}
+
+static unsigned int ps3vram_cache_match(struct mtd_info *mtd, loff_t address)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+	struct ps3vram_cache *cache = &priv->cache;
+	unsigned int base;
+	unsigned int offset;
+	int i;
+	static int counter;
+
+	offset = (unsigned int) (address & (cache->page_size - 1));
+	base = (unsigned int) (address - offset);
+
+	/* fully associative check */
+	for (i = 0; i < cache->page_count; i++) {
+		if ((cache->tags[i].flags & CACHE_PAGE_PRESENT) &&
+		    cache->tags[i].address == base) {
+			dbg("found entry %d : 0x%08x",
+			    i, cache->tags[i].address);
+			return i;
+		}
+	}
+
+	/* choose a random entry */
+	i = (jiffies + (counter++)) % cache->page_count;
+	dbg("using cache entry %d", i);
+
+	ps3vram_cache_evict(mtd, i);
+	ps3vram_cache_load(mtd, i, base);
+
+	return i;
+}
+
+static int ps3vram_cache_init(struct mtd_info *mtd)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+
+	pr_info("creating cache: %d entries, %d bytes pages\n",
+	       CACHE_PAGE_COUNT, CACHE_PAGE_SIZE);
+
+	priv->cache.page_count = CACHE_PAGE_COUNT;
+	priv->cache.page_size = CACHE_PAGE_SIZE;
+	priv->cache.tags = kzalloc(sizeof(struct ps3vram_tag) *
+				   CACHE_PAGE_COUNT, GFP_KERNEL);
+	if (priv->cache.tags == NULL) {
+		pr_err("could not allocate cache tags\n");
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static void ps3vram_cache_cleanup(struct mtd_info *mtd)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+
+	ps3vram_cache_flush(mtd);
+	kfree(priv->cache.tags);
+}
+
+static int ps3vram_erase(struct mtd_info *mtd, struct erase_info *instr)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+
+	if (instr->addr + instr->len > mtd->size)
+		return -EINVAL;
+
+	mutex_lock(&priv->lock);
+
+	ps3vram_cache_flush(mtd);
+
+	/* Set bytes to 0xFF */
+	memset(priv->base + instr->addr, 0xFF, instr->len);
+
+	mutex_unlock(&priv->lock);
+
+	instr->state = MTD_ERASE_DONE;
+	mtd_erase_callback(instr);
+
+	return 0;
+}
+
+
+static int ps3vram_read(struct mtd_info *mtd, loff_t from, size_t len,
+			size_t *retlen, u_char *buf)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+	unsigned int cached, count;
+
+	dbg("from = 0x%08x len = 0x%zx", (unsigned int) from, len);
+
+	if (from >= mtd->size)
+		return -EINVAL;
+
+	if (len > mtd->size - from)
+		len = mtd->size - from;
+
+	/* Copy from vram to buf */
+	count = len;
+	while (count) {
+		unsigned int offset, avail;
+		unsigned int entry;
+
+		offset = (unsigned int) (from & (priv->cache.page_size - 1));
+		avail  = priv->cache.page_size - offset;
+
+		mutex_lock(&priv->lock);
+
+		entry = ps3vram_cache_match(mtd, from);
+		cached = CACHE_OFFSET + entry * priv->cache.page_size + offset;
+
+		dbg("from=%08x cached=%08x offset=%08x avail=%08x count=%08x",
+		    (unsigned)from, cached, offset, avail, count);
+
+		if (avail > count)
+			avail = count;
+		memcpy(buf, priv->xdr_buf + cached, avail);
+
+		mutex_unlock(&priv->lock);
+
+		buf += avail;
+		count -= avail;
+		from += avail;
+	}
+
+	*retlen = len;
+	return 0;
+}
+
+static int ps3vram_write(struct mtd_info *mtd, loff_t to, size_t len,
+			 size_t *retlen, const u_char *buf)
+{
+	struct ps3vram_priv *priv = mtd->priv;
+	unsigned int cached, count;
+
+	if (to >= mtd->size)
+		return -EINVAL;
+
+	if (len > mtd->size - to)
+		len = mtd->size - to;
+
+	/* Copy from buf to vram */
+	count = len;
+	while (count) {
+		unsigned int offset, avail;
+		unsigned int entry;
+
+		offset = (unsigned int) (to & (priv->cache.page_size - 1));
+		avail  = priv->cache.page_size - offset;
+
+		mutex_lock(&priv->lock);
+
+		entry = ps3vram_cache_match(mtd, to);
+		cached = CACHE_OFFSET + entry * priv->cache.page_size + offset;
+
+		dbg("to=%08x cached=%08x offset=%08x avail=%08x count=%08x",
+		    (unsigned) to, cached, offset, avail, count);
+
+		if (avail > count)
+			avail = count;
+		memcpy(priv->xdr_buf + cached, buf, avail);
+
+		priv->cache.tags[entry].flags |= CACHE_PAGE_DIRTY;
+
+		mutex_unlock(&priv->lock);
+
+		buf += avail;
+		count -= avail;
+		to += avail;
+	}
+
+	*retlen = len;
+	return 0;
+}
+
+static int __devinit ps3vram_probe(struct ps3_system_bus_device *dev)
+{
+	struct ps3vram_priv *priv;
+	uint64_t status;
+	uint64_t ddr_lpar, ctrl_lpar, info_lpar, reports_lpar;
+	int64_t ddr_size;
+	uint64_t reports_size;
+	int ret = -ENOMEM;
+	char *rest;
+
+	ret = -EIO;
+	ps3vram_mtd.priv = kzalloc(sizeof(struct ps3vram_priv), GFP_KERNEL);
+	if (!ps3vram_mtd.priv)
+		goto out;
+	priv = ps3vram_mtd.priv;
+
+	mutex_init(&priv->lock);
+
+	/* Allocate XDR buffer (1MiB aligned) */
+	priv->xdr_buf = (uint8_t *) __get_free_pages(GFP_KERNEL,
+						     get_order(XDR_BUF_SIZE));
+	if (priv->xdr_buf == NULL) {
+		pr_err("ps3vram: could not allocate XDR buffer\n");
+		ret = -ENOMEM;
+		goto out_free_priv;
+	}
+
+	/* Put FIFO at begginning of XDR buffer */
+	priv->fifo_base = (uint32_t *) (priv->xdr_buf + FIFO_OFFSET);
+	priv->fifo_ptr = priv->fifo_base;
+
+	/* XXX: Need to open GPU, in case ps3fb or snd_ps3 aren't loaded */
+	if (ps3_open_hv_device(dev)) {
+		pr_err("ps3vram: ps3_open_hv_device failed\n");
+		ret = -EAGAIN;
+		goto out_close_gpu;
+	}
+
+	/* Request memory */
+	status = -1;
+	ddr_size = memparse(size, &rest);
+	if (*rest == '-')
+		ddr_size -= ps3fb_videomemory.size;
+	ddr_size = ALIGN(ddr_size, 1024*1024);
+	if (ddr_size <= 0) {
+		printk(KERN_ERR "ps3vram: specified size is too small\n");
+		ret = -EINVAL;
+		goto out_close_gpu;
+	}
+
+	while (ddr_size > 0) {
+		status = lv1_gpu_memory_allocate(ddr_size, 0, 0, 0, 0,
+						 &priv->memory_handle,
+						 &ddr_lpar);
+		if (status == 0)
+			break;
+		ddr_size -= 1024*1024;
+	}
+	if (status != 0 || ddr_size <= 0) {
+		pr_err("ps3vram: lv1_gpu_memory_allocate failed\n");
+		ret = -ENOMEM;
+		goto out_free_xdr_buf;
+	}
+	pr_info("ps3vram: allocated %u MiB of DDR memory\n",
+		(unsigned int) (ddr_size / 1024 / 1024));
+
+	/* Request context */
+	status = lv1_gpu_context_allocate(priv->memory_handle,
+					  0,
+					  &priv->context_handle,
+					  &ctrl_lpar,
+					  &info_lpar,
+					  &reports_lpar,
+					  &reports_size);
+	if (status) {
+		pr_err("ps3vram: lv1_gpu_context_allocate failed\n");
+		ret = -ENOMEM;
+		goto out_free_memory;
+	}
+
+	/* Map XDR buffer to RSX */
+	status = lv1_gpu_context_iomap(priv->context_handle, XDR_IOIF,
+				       ps3_mm_phys_to_lpar(__pa(priv->xdr_buf)),
+				       XDR_BUF_SIZE, 0);
+	if (status) {
+		pr_err("ps3vram: lv1_gpu_context_iomap failed\n");
+		ret = -ENOMEM;
+		goto out_free_context;
+	}
+
+	priv->base = ioremap(ddr_lpar, ddr_size);
+	if (!priv->base) {
+		pr_err("ps3vram: ioremap failed\n");
+		ret = -ENOMEM;
+		goto out_free_context;
+	}
+
+	priv->ctrl = ioremap(ctrl_lpar, 64 * 1024);
+	if (!priv->ctrl) {
+		pr_err("ps3vram: ioremap failed\n");
+		ret = -ENOMEM;
+		goto out_unmap_vram;
+	}
+
+	priv->reports = ioremap(reports_lpar, reports_size);
+	if (!priv->reports) {
+		pr_err("ps3vram: ioremap failed\n");
+		ret = -ENOMEM;
+		goto out_unmap_ctrl;
+	}
+
+	mutex_lock(&ps3_gpu_mutex);
+	ps3vram_init_ring(&ps3vram_mtd);
+	mutex_unlock(&ps3_gpu_mutex);
+
+	ps3vram_mtd.name = "ps3vram";
+	ps3vram_mtd.size = ddr_size;
+	ps3vram_mtd.flags = MTD_CAP_RAM;
+	ps3vram_mtd.erase = ps3vram_erase;
+	ps3vram_mtd.point = NULL;
+	ps3vram_mtd.unpoint = NULL;
+	ps3vram_mtd.read = ps3vram_read;
+	ps3vram_mtd.write = ps3vram_write;
+	ps3vram_mtd.owner = THIS_MODULE;
+	ps3vram_mtd.type = MTD_RAM;
+	ps3vram_mtd.erasesize = CACHE_PAGE_SIZE;
+	ps3vram_mtd.writesize = 1;
+
+	ps3vram_bind(&ps3vram_mtd);
+
+	mutex_lock(&ps3_gpu_mutex);
+	ret = ps3vram_wait_ring(&ps3vram_mtd, 100);
+	mutex_unlock(&ps3_gpu_mutex);
+	if (ret < 0) {
+		pr_err("failed to initialize channels\n");
+		ret = -ETIMEDOUT;
+		goto out_unmap_reports;
+	}
+
+	ps3vram_cache_init(&ps3vram_mtd);
+
+	if (add_mtd_device(&ps3vram_mtd)) {
+		pr_err("ps3vram: failed to register device\n");
+		ret = -EAGAIN;
+		goto out_cache_cleanup;
+	}
+
+	pr_info("ps3vram mtd device registered, %lu bytes\n", ddr_size);
+	return 0;
+
+out_cache_cleanup:
+	ps3vram_cache_cleanup(&ps3vram_mtd);
+out_unmap_reports:
+	iounmap(priv->reports);
+out_unmap_ctrl:
+	iounmap(priv->ctrl);
+out_unmap_vram:
+	iounmap(priv->base);
+out_free_context:
+	lv1_gpu_context_free(priv->context_handle);
+out_free_memory:
+	lv1_gpu_memory_free(priv->memory_handle);
+out_close_gpu:
+	ps3_close_hv_device(dev);
+out_free_xdr_buf:
+	free_pages((unsigned long) priv->xdr_buf, get_order(XDR_BUF_SIZE));
+out_free_priv:
+	kfree(ps3vram_mtd.priv);
+	ps3vram_mtd.priv = NULL;
+out:
+	return ret;
+}
+
+static int ps3vram_shutdown(struct ps3_system_bus_device *dev)
+{
+	struct ps3vram_priv *priv;
+
+	priv = ps3vram_mtd.priv;
+
+	del_mtd_device(&ps3vram_mtd);
+	ps3vram_cache_cleanup(&ps3vram_mtd);
+	iounmap(priv->reports);
+	iounmap(priv->ctrl);
+	iounmap(priv->base);
+	lv1_gpu_context_free(priv->context_handle);
+	lv1_gpu_memory_free(priv->memory_handle);
+	ps3_close_hv_device(dev);
+	free_pages((unsigned long) priv->xdr_buf, get_order(XDR_BUF_SIZE));
+	kfree(priv);
+	return 0;
+}
+
+static struct ps3_system_bus_driver ps3vram_driver = {
+	.match_id	= PS3_MATCH_ID_GPU,
+	.match_sub_id	= PS3_MATCH_SUB_ID_GPU_RAMDISK,
+	.core.name	= DEVICE_NAME,
+	.core.owner	= THIS_MODULE,
+	.probe		= ps3vram_probe,
+	.remove		= ps3vram_shutdown,
+	.shutdown	= ps3vram_shutdown,
+};
+
+static int __init ps3vram_init(void)
+{
+	return ps3_system_bus_driver_register(&ps3vram_driver);
+}
+
+static void __exit ps3vram_exit(void)
+{
+	ps3_system_bus_driver_unregister(&ps3vram_driver);
+}
+
+module_init(ps3vram_init);
+module_exit(ps3vram_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Jim Paris <jim@jtan.com>");
+MODULE_DESCRIPTION("MTD driver for PS3 video RAM");