diff options
author | Thomas Bushnell <thomas@gnu.org> | 1999-04-26 05:49:38 +0000 |
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committer | Thomas Bushnell <thomas@gnu.org> | 1999-04-26 05:49:38 +0000 |
commit | 59ec5ca501a2f5d9fc2b2c41d474ec30e4fd67ee (patch) | |
tree | 97ace5e7a72b66e98b9210b7e99fc7f30d674e80 /linux/dev/kernel/dma.c | |
parent | 195a918c4a64e79bfccb585801aeec0077d68a24 (diff) |
1998-12-02 OKUJI Yoshinori <okuji@kuicr.kyoto-u.ac.jp>
* configure.in: Fix linuxdev option handling.
* linux/Drivers.in: Remove linuxdev option and fix linking files.
* linux/Makefile.in: Replace @DEFS@ with -DLINUX_DEV.
* linux/dev/arch/i386/kernel/irq.c: Include missing header files.
* linux/dev/arch/i386/kernel/setup.c: Include <device-drivers.h>.
* linux/dev/glue/kmem.c: Add printf declaration.
* linux/dev/glue/misc.c: Include <linux/types.h>.
* linux/dev/init/main.c: Call linux_sched_init instead of sched_init.
* linux/dev/kernel/sched.c: Add timer_bh declaration.
(tqueue_bh): Fix the argument.
(linux_sched_init): Renamed from sched_init.
1998-11-30 OKUJI Yoshinori <okuji@kuicr.kyoto-u.ac.jp>
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 <i386/ipl.h>, for compatibility with
OSF Mach 3.0. Suggested by Elgin Lee <ehl@funghi.com>.
* 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 <machine/spl.h> instead
of <i386/ipl.h>.
* linux/dev/drivers/net/auto_irq.c: Remove unneeded header files,
<i386/ipl.h> and <i386/pic.h>.
* 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 <machine/spl.h> instead
of <i386/ipl.h>, and moved to ...
* linux/dev/kernel/sched.c: ... here.
* linux/dev/arch/i386/glue/block.c: Include <machine/spl.h> and
<linux_emul.h>, instead of i386-dependent header files, and
moved to ...
* linux/dev/glue/blocl.c: ... here.
* linux/dev/arch/i386/glue/net.c: Include <machine/spl.h> and
<linux_emul.h>, 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.
Diffstat (limited to 'linux/dev/kernel/dma.c')
-rw-r--r-- | linux/dev/kernel/dma.c | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/linux/dev/kernel/dma.c b/linux/dev/kernel/dma.c new file mode 100644 index 0000000..4b56978 --- /dev/null +++ b/linux/dev/kernel/dma.c @@ -0,0 +1,109 @@ +/* $Id: dma.c,v 1.1 1999/04/26 05:49:35 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] + */ + +#define MACH_INCLUDE +#include <linux/kernel.h> +#include <linux/errno.h> +#include <asm/dma.h> +#include <asm/system.h> + + +/* 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 } +}; + +#ifndef MACH +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 += linux_sprintf (buf+len, "%2d: %s\n", + i, + dma_chan_busy[i].device_id); + } + } + return len; +} /* get_dma_list */ +#endif + +int +request_dma (unsigned int dmanr, const char *device_id) +{ + if (dmanr >= MAX_DMA_CHANNELS) + return -LINUX_EINVAL; + + if (xchg (&dma_chan_busy[dmanr].lock, 1) != 0) + return -LINUX_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 */ |