From 86297c41a26f18d924e64fc93321c59cbc4c48dd Mon Sep 17 00:00:00 2001 From: Thomas Bushnell Date: Mon, 26 Apr 1999 05:58:44 +0000 Subject: 1998-11-30 OKUJI Yoshinori Clean up linux emulation code to make it architecture-independent as much as possible. * linux: Renamed from linuxdev. * Makefile.in (objfiles): Add linux.o instead of linuxdev.o. (MAKE): New variable. Used for the linux.o target. * configure.in: Add AC_CHECK_TOOL(MAKE, make). * i386/i386/spl.h: Include , for compatibility with OSF Mach 3.0. Suggested by Elgin Lee . * linux/src: Renamed from linux/linux. * linux/dev: Renamed from linux/mach. * linux/Drivers.in (AC_INIT): Use dev/include/linux/autoconf.h, instead of mach/include/linux/autoconf.h. * Makefile.in (all): Target ../linux.o instead of ../linuxdev.o. * linux/dev/drivers/block/genhd.c: Include instead of . * linux/dev/drivers/net/auto_irq.c: Remove unneeded header files, and . * linux/dev/init/main.c: Many i386-dependent codes moved to ... * linux/dev/arch/i386/irq.c: ... here. * linux/dev/arch/i386/setup.c: New file. * linux/dev/arch/i386/linux_emul.h: Likewise. * linux/dev/arch/i386/glue/timer.c: Merged into sched.c. * linux/dev/arch/i386/glue/sched.c: Include instead of , and moved to ... * linux/dev/kernel/sched.c: ... here. * linux/dev/arch/i386/glue/block.c: Include and , instead of i386-dependent header files, and moved to ... * linux/dev/glue/blocl.c: ... here. * linux/dev/arch/i386/glue/net.c: Include and , instead of i386-dependent header files, and moved to ... * linux/dev/glue/net.c: ... here. * linux/dev/arch/i386/glue/misc.c: Remove `x86' and moved to ... * linux/dev/glue/misc.c: ... here. * linux/dev/arch/i386/glue/kmem.c: Moved to ... * linux/dev/glue/kmem.c: ... here. --- linux/src/kernel/dma.c | 99 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 99 insertions(+) create mode 100644 linux/src/kernel/dma.c (limited to 'linux/src/kernel/dma.c') diff --git a/linux/src/kernel/dma.c b/linux/src/kernel/dma.c new file mode 100644 index 00000000..724d8ca2 --- /dev/null +++ b/linux/src/kernel/dma.c @@ -0,0 +1,99 @@ +/* $Id: dma.c,v 1.1 1999/04/26 05:58:29 tb Exp $ + * linux/kernel/dma.c: A DMA channel allocator. Inspired by linux/kernel/irq.c. + * + * Written by Hennus Bergman, 1992. + * + * 1994/12/26: Changes by Alex Nash to fix a minor bug in /proc/dma. + * In the previous version the reported device could end up being wrong, + * if a device requested a DMA channel that was already in use. + * [It also happened to remove the sizeof(char *) == sizeof(int) + * assumption introduced because of those /proc/dma patches. -- Hennus] + */ + +#include +#include +#include +#include + + +/* A note on resource allocation: + * + * All drivers needing DMA channels, should allocate and release them + * through the public routines `request_dma()' and `free_dma()'. + * + * In order to avoid problems, all processes should allocate resources in + * the same sequence and release them in the reverse order. + * + * So, when allocating DMAs and IRQs, first allocate the IRQ, then the DMA. + * When releasing them, first release the DMA, then release the IRQ. + * If you don't, you may cause allocation requests to fail unnecessarily. + * This doesn't really matter now, but it will once we get real semaphores + * in the kernel. + */ + + + +/* Channel n is busy iff dma_chan_busy[n].lock != 0. + * DMA0 used to be reserved for DRAM refresh, but apparently not any more... + * DMA4 is reserved for cascading. + */ + +struct dma_chan { + int lock; + const char *device_id; +}; + +static struct dma_chan dma_chan_busy[MAX_DMA_CHANNELS] = { + { 0, 0 }, + { 0, 0 }, + { 0, 0 }, + { 0, 0 }, + { 1, "cascade" }, + { 0, 0 }, + { 0, 0 }, + { 0, 0 } +}; + +int get_dma_list(char *buf) +{ + int i, len = 0; + + for (i = 0 ; i < MAX_DMA_CHANNELS ; i++) { + if (dma_chan_busy[i].lock) { + len += sprintf(buf+len, "%2d: %s\n", + i, + dma_chan_busy[i].device_id); + } + } + return len; +} /* get_dma_list */ + + +int request_dma(unsigned int dmanr, const char * device_id) +{ + if (dmanr >= MAX_DMA_CHANNELS) + return -EINVAL; + + if (xchg(&dma_chan_busy[dmanr].lock, 1) != 0) + return -EBUSY; + + dma_chan_busy[dmanr].device_id = device_id; + + /* old flag was 0, now contains 1 to indicate busy */ + return 0; +} /* request_dma */ + + +void free_dma(unsigned int dmanr) +{ + if (dmanr >= MAX_DMA_CHANNELS) { + printk("Trying to free DMA%d\n", dmanr); + return; + } + + if (xchg(&dma_chan_busy[dmanr].lock, 0) == 0) { + printk("Trying to free free DMA%d\n", dmanr); + return; + } + +} /* free_dma */ -- cgit v1.2.3