summaryrefslogtreecommitdiff
path: root/linux/dev/kernel/dma.c
diff options
context:
space:
mode:
authorThomas Bushnell <thomas@gnu.org>1999-04-26 05:49:38 +0000
committerThomas Bushnell <thomas@gnu.org>1999-04-26 05:49:38 +0000
commit59ec5ca501a2f5d9fc2b2c41d474ec30e4fd67ee (patch)
tree97ace5e7a72b66e98b9210b7e99fc7f30d674e80 /linux/dev/kernel/dma.c
parent195a918c4a64e79bfccb585801aeec0077d68a24 (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.c109
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 */