diff options
Diffstat (limited to 'backends/platform/gph/devices/gp2x/mmuhack')
| -rw-r--r-- | backends/platform/gph/devices/gp2x/mmuhack/Makefile | 11 | ||||
| -rw-r--r-- | backends/platform/gph/devices/gp2x/mmuhack/flush_uppermem_cache.h | 11 | ||||
| -rw-r--r-- | backends/platform/gph/devices/gp2x/mmuhack/flush_uppermem_cache.s | 6 | ||||
| -rw-r--r-- | backends/platform/gph/devices/gp2x/mmuhack/mmuhack.c | 129 | ||||
| -rw-r--r-- | backends/platform/gph/devices/gp2x/mmuhack/mmuhack.o | bin | 0 -> 1720 bytes | |||
| -rw-r--r-- | backends/platform/gph/devices/gp2x/mmuhack/readme.txt | 110 |
6 files changed, 267 insertions, 0 deletions
diff --git a/backends/platform/gph/devices/gp2x/mmuhack/Makefile b/backends/platform/gph/devices/gp2x/mmuhack/Makefile new file mode 100644 index 0000000000..a35d5c2a98 --- /dev/null +++ b/backends/platform/gph/devices/gp2x/mmuhack/Makefile @@ -0,0 +1,11 @@ +TARGET = mmuhack +INCLUDE = -I/opt/gcc-3.4.4-glibc-2.3.6/arm-open2x-linux/sys-include +CFLAGS = -O2 -DMODULE -D__KERNEL__ ${INCLUDE} +CC = arm-open2x-linux-gcc + +all: ${TARGET}.o + +${TARGET}.o: ${TARGET}.c + +clean: + rm -rf ${TARGET}.o diff --git a/backends/platform/gph/devices/gp2x/mmuhack/flush_uppermem_cache.h b/backends/platform/gph/devices/gp2x/mmuhack/flush_uppermem_cache.h new file mode 100644 index 0000000000..520841ace7 --- /dev/null +++ b/backends/platform/gph/devices/gp2x/mmuhack/flush_uppermem_cache.h @@ -0,0 +1,11 @@ +#ifdef __cplusplus +extern "C" +{ +#endif + +void flush_uppermem_cache(void *start_address, void *end_address, int flags); + +#ifdef __cplusplus +} +#endif + diff --git a/backends/platform/gph/devices/gp2x/mmuhack/flush_uppermem_cache.s b/backends/platform/gph/devices/gp2x/mmuhack/flush_uppermem_cache.s new file mode 100644 index 0000000000..17628c156a --- /dev/null +++ b/backends/platform/gph/devices/gp2x/mmuhack/flush_uppermem_cache.s @@ -0,0 +1,6 @@ +.global flush_uppermem_cache @ void *start_address, void *end_address, int flags + +flush_uppermem_cache: + swi #0x9f0002 + bx lr + diff --git a/backends/platform/gph/devices/gp2x/mmuhack/mmuhack.c b/backends/platform/gph/devices/gp2x/mmuhack/mmuhack.c new file mode 100644 index 0000000000..7e27262e5f --- /dev/null +++ b/backends/platform/gph/devices/gp2x/mmuhack/mmuhack.c @@ -0,0 +1,129 @@ +/* ScummVM - Graphic Adventure Engine + * + * ScummVM is the legal property of its developers, whose names + * are too numerous to list here. Please refer to the COPYRIGHT + * file distributed with this source distribution. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + + * 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. + + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + * + * $URL$ + * $Id$ + * + */ + +#include <linux/config.h> +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/miscdevice.h> +#include <asm/memory.h> + +#define MMUHACK_MINOR 225 +#define DEVICE_NAME "mmuhack" + +#if __GNUC__ == 3 +#include <linux/version.h> +static const char __module_kernel_version_gcc3[] __attribute__((__used__)) __attribute__((section(".modinfo"))) = +"kernel_version=" UTS_RELEASE; +#endif + +static ssize_t mmuhack_open(struct inode *inode, struct file *filp) +{ + unsigned int *pgtable; + unsigned int *cpt; + int i, j; + int ttb; + int ret = -EFAULT; + + // get the pointer to the translation table base... + asm volatile( + "stmdb sp!, {r0}\n\t" + "mrc p15, 0, r0, c2, c0, 0\n\t" + "mov %0, r0\n\t" + "ldmia sp!, {r0}\n\t": "=r"(ttb) + ); + + pgtable = __va(ttb); + + for (i = 0; i < 4096; i ++) if ( (pgtable[i] & 3) == 1 ) { + cpt = __va(pgtable[i] & 0xfffffc00); + + for (j = 0; j < 256; j ++) {/* + if ( (cpt[j] & 0xfe00000f) == 0x02000002 ) { + // set C and B bits in upper 32MB memory area... + printk("Set C&B bits %08x\n",cpt[j]); + cpt[j] |= 0xFFC; + ret = 0; + } + */ + if (((cpt[j] & 0xff000000) == 0x02000000) && ((cpt[j] & 12)==0) ) + { + //printk("Set C&B bits %08x\n",cpt[j]); + cpt[j] |= 0xFFC; + } + //if ((a>=0x31 && a<=0x36) && ((cpt[i] & 12)==0)) + if (((cpt[j] & 0xff000000) == 0x03000000) && ((cpt[j] & 12)==0)) + { + //printk("Set C&B bits %08x\n",cpt[j]); + //printf("SDL c and b bits not set, overwriting\n"); + cpt[j] |= 0xFFC; + } + } + } + + // drain the write buffer and flush the tlb caches... + asm volatile( + "stmdb sp!, {r0}\n\t" + "mov r0, #0\n\t" + "mcr 15, 0, r0, cr7, cr10, 4\n\t" + "mcr 15, 0, r0, cr8, cr7, 0\n\t" + "ldmia sp!, {r0}\n\t" + ); + + if (ret == 0) + printk("MMU hack applied.\n"); + + return 0; +} + +static struct file_operations mmuhack_fops = { + owner: THIS_MODULE, + open: mmuhack_open, +}; + + +static struct miscdevice mmuhack = { + MMUHACK_MINOR, DEVICE_NAME, &mmuhack_fops +}; + +static int __init mmuhack_init(void) +{ + misc_register(&mmuhack); +/* + printk("MMSP2 MMU Hack module.\n"); +*/ + return 0; +} + +static void __exit mmuhack_exit(void) +{ + misc_deregister(&mmuhack); +/* + printk(KERN_ALERT "MMU Hack module removed.\n"); +*/ +} + +module_init(mmuhack_init); +module_exit(mmuhack_exit); diff --git a/backends/platform/gph/devices/gp2x/mmuhack/mmuhack.o b/backends/platform/gph/devices/gp2x/mmuhack/mmuhack.o Binary files differnew file mode 100644 index 0000000000..475f4a54ae --- /dev/null +++ b/backends/platform/gph/devices/gp2x/mmuhack/mmuhack.o diff --git a/backends/platform/gph/devices/gp2x/mmuhack/readme.txt b/backends/platform/gph/devices/gp2x/mmuhack/readme.txt new file mode 100644 index 0000000000..bea49d7d6d --- /dev/null +++ b/backends/platform/gph/devices/gp2x/mmuhack/readme.txt @@ -0,0 +1,110 @@ +About +----- + +This is a module for GP2X 2.4 based Linux kernel, created for developers to use in their +programs. + +Normally the upper 32MB is uncached. This means that reads/writes on the memory +are always done via the physical memory modules rather than the much faster +memory built into the processor (called 'cache'). Access to the upper 32MB can +be sped up by Squidge's MMU hack. The easiest way to use the MMU hack is to add +and load the MMU hack kernel module into your program. + +Note: Building this module requries a GP2X 'kernel' toolchain (i.e. GCC 2.95.* +for the GP2X stock, 3.* for Open2X). + +You can't build this module with the GCC 4 based application toolchains. + +Operation +--------- + +When loaded into kernel, this module creates /dev/mmuhack device. Whenever +a program opens that device using open() call, the module traverses all +memory, which was allocated in 0x02000000-0x03ffffff range by the program via +using mmap() system call. While doing that, it marks all encountered memory +as bufferable and cacheable. + +The most common use of this is to remove the framebuffer access bottleneck. +Note that, however, by making the framebuffer cacheable you can cause display +artifacts. This can happen because parts of your framebuffer may stay in CPU +cache and not to be written back to the physical memory. The display +controller only fetches data from the physical memory, so you get incomplete +image (the memory will most likely contain data from previous frame, so these +artifacts are better visible during fade effects). The easy way to fix this +is by using a special ARM Linux system call, which flushes the cache (forces +the CPU to write data in cache to the physical memory (see section "Flushing +the cache")). + +Using this module affects the whole upper memory area. But in some situations +this may be not desirable, for example when using ARM940 core in your program +(ether using 940 libraries like ogg940 and gpu940, or using your custom code, +which needs uncacheable memory for communication and such). If you need part +of your upper memory to be cached, and other part not, you should mmap() that +memory (which you want to be uncached) _after_ doing open("/dev/mmuhack"). +Another way is to modify mmuhack.c to suit your needs and rebuild the module. + + +Usage +----- + +The very first thing to do is to load the kernel module (mmuhack.o) into the +running kernel. But before that you should try to unload mmuhack module, +because other program might have left a different version loaded with +different memory configuration, which may not suit your program. + +system("/sbin/rmmod mmuhack"); +system("/sbin/insmod mmuhack.o"); + +Now you can assume the module is loaded into kernel and open /dev/mmuhack +device. You don't need to worry about previous calls failing, because in that +case open() will simply fail and nothing bad will happen. + +IMPORTANT: you _must_ do the open() call _after_ you initialize your graphics +library or allocate your memory, because it can only work with memory which is +already allocated, it won't affect memory you or your lib allocates after the +open() call. + +int mmufd = open("/dev/mmuhack", O_RDWR); +if(mmufd < 0) +{ + printf("MMU hack failed"); +} +else +{ + printf("MMU hack loaded"); + close(mmufd); +} + +If the above call succeeded, you are all done. +I recommend to unload the module when your program exits, because the other +program may want to load a different mmuhack.o and may fail, because you left +your mmuhack.o loaded (it does not get unloaded automatically on exit). + +system("/sbin/rmmod mmuhack"); + + +Flushing the cache +------------------ + +If using mmuhack.o causes your program to display artifacts (see "Operation" +section for explanation), you will need to flush the CPU cache. This should +be done after finishing every frame and just before flipping your display +buffer/surface. You will need to add flush_uppermem_cache.s file to your +Makefile/project and add a call to flush_uppermem_cache() just before final +framebuffer flip or blit. + +flush_uppermem_cache() has 3 parameters. First param is the start address, +second param is the end address, third one should always be 0. The addresses +should be virtual ones (most often pointers to the start/end of your +framebuffer). Example: + +flush_uppermem_cache(screen_surface->pixels, screen_surface->pixels + 320*240, 0); + + +Credits +------- + +Original idea/implementation: Squidge (this whole thing is also known as squidgehack) +Kernel module: NK +Documentation: notaz + |