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 @@ static int __init ps3_register_graphics_devices(void)
 	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