[ARM PATCH] 1993/3: S3C2410 DMA Support

Patch from Ben Dooks

Support for DMA controller on the Samsung S3C2410,
and fixes to the header files for DMA register definitions


Fixes the menuconfig problem from the original patch

4 files changed, 1117 insertions, 0 deletions

diff --git a/arch/arm/configs/s3c2410_defconfig b/arch/arm/configs/s3c2410_defconfig
index d9e45878ffac6c..9919e7ff08600f 100644
--- a/arch/arm/configs/s3c2410_defconfig
+++ b/arch/arm/configs/s3c2410_defconfig
@@ -78,6 +78,12 @@ CONFIG_ARCH_SMDK2410=y
 CONFIG_MACH_VR1000=y
 
 #
+# S3C2410 Setup
+#
+CONFIG_S3C2410_DMA=y
+# CONFIG_S3C2410_DMA_DEBUG is not set
+
+#
 # Processor Type
 #
 CONFIG_CPU_32=y
@@ -601,6 +607,8 @@ CONFIG_ROMFS_FS=y
 CONFIG_FAT_FS=y
 CONFIG_MSDOS_FS=y
 CONFIG_VFAT_FS=y
+CONFIG_FAT_DEFAULT_CODEPAGE=437
+CONFIG_FAT_DEFAULT_IOCHARSET="iso8859-1"
 # CONFIG_NTFS_FS is not set
 
 #
diff --git a/arch/arm/mach-s3c2410/Kconfig b/arch/arm/mach-s3c2410/Kconfig
index 40e78bc4460a19..6e10ac8b65409a 100644
--- a/arch/arm/mach-s3c2410/Kconfig
+++ b/arch/arm/mach-s3c2410/Kconfig
@@ -32,4 +32,26 @@ config MACH_VR1000
 
 endmenu
 
+comment "S3C2410 Setup"
+
+config S3C2410_DMA
+	bool "S3C2410 DMA support"
+	depends on ARCH_S3C2410
+	help
+	  S3C2410 DMA support. This is needed for drivers like sound which
+	  use the S3C2410's DMA system to move data to and from the
+	  peripheral blocks.
+
+config S3C2410_DMA_DEBUG
+	bool "S3C2410 DMA support debug"
+	depends on ARCH_S3C2410 && S3C2410_DMA
+	help
+	  Enable debugging output for the DMA code. This option sends info
+	  to the kernel log, at priority KERN_DEBUG.
+
+	  Note, it is easy to create and fill the log buffer in a small
+	  amount of time, as well as using an significant percantage of
+	  the CPU time doing so.
+
+
 endif
diff --git a/arch/arm/mach-s3c2410/Makefile b/arch/arm/mach-s3c2410/Makefile
index 6c63197fba9c93..d81560cb455e29 100644
--- a/arch/arm/mach-s3c2410/Makefile
+++ b/arch/arm/mach-s3c2410/Makefile
@@ -9,6 +9,8 @@ obj-m			:=
 obj-n			:=
 obj-			:=
 
+obj-$(CONFIG_S3C2410_DMA)  += dma.o
+
 obj-$(CONFIG_ARCH_BAST)    += mach-bast.o
 obj-$(CONFIG_MACH_H1940)   += mach-h1940.o
 obj-$(CONFIG_ARCH_H1940)   += mach-h1940.o
diff --git a/arch/arm/mach-s3c2410/dma.c b/arch/arm/mach-s3c2410/dma.c
new file mode 100644
index 00000000000000..819e5af16e1e68
--- /dev/null
+++ b/arch/arm/mach-s3c2410/dma.c
@@ -0,0 +1,1085 @@
+/* linux/arch/arm/mach-bast/dma.c
+ *
+ * (c) 2003,2004 Simtec Electronics
+ * Ben Dooks <ben@simtec.co.uk>
+ *
+ * S3C2410 DMA core
+ *
+ * http://www.simtec.co.uk/products/EB2410ITX/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Changelog:
+ *  08-Aug-2004 BJD  Apply rmk's suggestions
+ *  21-Jul-2004 BJD  Ported to linux 2.6
+ *  12-Jul-2004 BJD  Finished re-write and change of API
+ *  06-Jul-2004 BJD  Rewrote dma code to try and cope with various problems
+ *  23-May-2003 BJD  Created file
+ *  19-Aug-2003 BJD  Cleanup, header fix, added URL
+ *
+ * This file is based on the Sangwook Lee/Samsung patches, re-written due
+ * to various ommisions from the code (such as flexible dma configuration)
+ * for use with the BAST system board.
+ *
+ * The re-write is pretty much complete, and should be good enough for any
+ * possible DMA function
+ */
+
+#include <linux/config.h>
+
+#ifdef CONFIG_S3C2410_DMA_DEBUG
+#define DEBUG
+#endif
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/delay.h>
+
+#include <asm/system.h>
+#include <asm/irq.h>
+#include <asm/hardware.h>
+#include <asm/io.h>
+#include <asm/dma.h>
+
+#include <asm/mach/dma.h>
+#include <asm/arch/map.h>
+
+/* io map for dma */
+static void *dma_base;
+
+/* dma channel state information */
+s3c2410_dma_chan_t s3c2410_chans[S3C2410_DMA_CHANNELS];
+
+/* debugging functions */
+
+#define BUF_MAGIC (0xcafebabe)
+
+#define dmawarn(fmt...) printk(KERN_DEBUG fmt)
+
+#define dma_regaddr(chan, reg) ((chan)->regs + (reg))
+
+#if 1
+#define dma_wrreg(chan, reg, val) writel((val), (chan)->regs + (reg))
+#else
+static inline void
+dma_wrreg(s3c2410_dma_chan_t *chan, int reg, unsigned long val)
+{
+	pr_debug("writing %08x to register %08x\n",(unsigned int)val,reg);
+	writel(val, dma_regaddr(chan, reg));
+}
+
+#endif
+
+#define dma_rdreg(chan, reg) readl((chan)->regs + (reg))
+
+/* captured register state for debug */
+
+struct s3c2410_dma_regstate {
+	unsigned long         dcsrc;
+	unsigned long         disrc;
+	unsigned long         dstat;
+	unsigned long         dcon;
+	unsigned long         dmsktrig;
+};
+
+#ifdef CONFIG_S3C2410_DMA_DEBUG
+
+/* dmadbg_showregs
+ *
+ * simple debug routine to print the current state of the dma registers
+*/
+
+static void
+dmadbg_capture(s3c2410_dma_chan_t *chan, struct s3c2410_dma_regstate *regs)
+{
+	regs->dcsrc    = dma_rdreg(chan, S3C2410_DMA_DCSRC);
+	regs->disrc    = dma_rdreg(chan, S3C2410_DMA_DISRC);
+	regs->dstat    = dma_rdreg(chan, S3C2410_DMA_DSTAT);
+	regs->dcon     = dma_rdreg(chan, S3C2410_DMA_DCON);
+	regs->dmsktrig = dma_rdreg(chan, S3C2410_DMA_DMASKTRIG);
+}
+
+static void
+dmadbg_showregs(const char *fname, int line, s3c2410_dma_chan_t *chan,
+		 struct s3c2410_dma_regstate *regs)
+{
+	printk(KERN_DEBUG "dma%d: %s:%d: DCSRC=%08lx, DISRC=%08lx, DSTAT=%08lx DMT=%02lx, DCON=%08lx\n",
+	       chan->number, fname, line,
+	       regs->dcsrc, regs->disrc, regs->dstat, regs->dmsktrig,
+	       regs->dcon);
+}
+
+static void
+dmadbg_showchan(const char *fname, int line, s3c2410_dma_chan_t *chan)
+{
+	struct s3c2410_dma_regstate state;
+
+	dmadbg_capture(chan, &state);
+
+	printk(KERN_DEBUG "dma%d: %s:%d: ls=%d, cur=%p, %p %p\n",
+	       chan->number, fname, line, chan->load_state,
+	       chan->curr, chan->next, chan->end);
+
+	dmadbg_showregs(fname, line, chan, &state);
+}
+
+#define dbg_showregs(chan) dmadbg_showregs(__FUNCTION__, __LINE__, (chan))
+#define dbg_showchan(chan) dmadbg_showchan(__FUNCTION__, __LINE__, (chan))
+#else
+#define dbg_showregs(chan) do { } while(0)
+#define dbg_showchan(chan) do { } while(0)
+#endif /* CONFIG_S3C2410_DMA_DEBUG */
+
+#define check_channel(chan) \
+  do { if ((chan) >= S3C2410_DMA_CHANNELS) { \
+    printk(KERN_ERR "%s: invalid channel %d\n", __FUNCTION__, (chan)); \
+    return -EINVAL; \
+  } } while(0)
+
+
+/* s3c2410_dma_stats_timeout
+ *
+ * Update DMA stats from timeout info
+*/
+
+static void
+s3c2410_dma_stats_timeout(s3c2410_dma_stats_t *stats, int val)
+{
+	if (stats == NULL)
+		return;
+
+	if (val > stats->timeout_longest)
+		stats->timeout_longest = val;
+	if (val < stats->timeout_shortest)
+		stats->timeout_shortest = val;
+
+	stats->timeout_avg += val;
+}
+
+/* s3c2410_dma_waitforload
+ *
+ * wait for the DMA engine to load a buffer, and update the state accordingly
+*/
+
+static int
+s3c2410_dma_waitforload(s3c2410_dma_chan_t *chan, int line)
+{
+	int timeout = chan->load_timeout;
+	int took;
+
+	if (chan->load_state != S3C2410_DMALOAD_1LOADED) {
+		printk(KERN_ERR "dma%d: s3c2410_dma_waitforload() called in loadstate %d from line %d\n", chan->number, chan->load_state, line);
+		return 0;
+	}
+
+	if (chan->stats != NULL)
+		chan->stats->loads++;
+
+	while (--timeout > 0) {
+		if ((dma_rdreg(chan, S3C2410_DMA_DSTAT) << (32-20)) != 0) {
+			took = chan->load_timeout - timeout;
+
+			s3c2410_dma_stats_timeout(chan->stats, took);
+
+			switch (chan->load_state) {
+			case S3C2410_DMALOAD_1LOADED:
+				chan->load_state = S3C2410_DMALOAD_1RUNNING;
+				break;
+
+			default:
+				printk(KERN_ERR "dma%d: unknown load_state in s3c2410_dma_waitforload() %d\n", chan->number, chan->load_state);
+			}
+
+			return 1;
+		}
+	}
+
+	if (chan->stats != NULL) {
+		chan->stats->timeout_failed++;
+	}
+
+	return 0;
+}
+
+
+
+/* s3c2410_dma_loadbuffer
+ *
+ * load a buffer, and update the channel state
+*/
+
+static inline int
+s3c2410_dma_loadbuffer(s3c2410_dma_chan_t *chan,
+		       s3c2410_dma_buf_t *buf)
+{
+	unsigned long reload;
+
+	pr_debug("s3c2410_chan_loadbuffer: loading buff %p (0x%08lx,0x%06x)\n",
+		 buf, (unsigned long)buf->data, buf->size);
+
+	if (buf == NULL) {
+		dmawarn("buffer is NULL\n");
+		return -EINVAL;
+	}
+
+	/* check the state of the channel before we do anything */
+
+	if (chan->load_state == S3C2410_DMALOAD_1LOADED) {
+		dmawarn("load_state is S3C2410_DMALOAD_1LOADED\n");
+	}
+
+	if (chan->load_state == S3C2410_DMALOAD_1LOADED_1RUNNING) {
+		dmawarn("state is S3C2410_DMALOAD_1LOADED_1RUNNING\n");
+	}
+
+	/* it would seem sensible if we are the last buffer to not bother
+	 * with the auto-reload bit, so that the DMA engine will not try
+	 * and load another transfer after this one has finished...
+	 */
+	if (chan->load_state == S3C2410_DMALOAD_NONE) {
+		pr_debug("load_state is none, checking for noreload (next=%p)\n",
+			 buf->next);
+		reload = (buf->next == NULL) ? S3C2410_DCON_NORELOAD : 0;
+	} else {
+		pr_debug("load_state is %d => autoreload\n", chan->load_state);
+		reload = S3C2410_DCON_AUTORELOAD;
+	}
+
+	writel(buf->data, chan->addr_reg);
+
+	dma_wrreg(chan, S3C2410_DMA_DCON,
+		  chan->dcon | reload | (buf->size/chan->xfer_unit));
+
+	chan->next = buf->next;
+
+	/* update the state of the channel */
+
+	switch (chan->load_state) {
+	case S3C2410_DMALOAD_NONE:
+		chan->load_state = S3C2410_DMALOAD_1LOADED;
+		break;
+
+	case S3C2410_DMALOAD_1RUNNING:
+		chan->load_state = S3C2410_DMALOAD_1LOADED_1RUNNING;
+		break;
+
+	default:
+		dmawarn("dmaload: unknown state %d in loadbuffer\n",
+			chan->load_state);
+		break;
+	}
+
+	return 0;
+}
+
+/* s3c2410_dma_call_op
+ *
+ * small routine to call the op routine with the given op if it has been
+ * registered
+*/
+
+static void
+s3c2410_dma_call_op(s3c2410_dma_chan_t *chan, s3c2410_chan_op_t op)
+{
+	if (chan->op_fn != NULL) {
+		(chan->op_fn)(chan, op);
+	}
+}
+
+/* s3c2410_dma_buffdone
+ *
+ * small wrapper to check if callback routine needs to be called, and
+ * if so, call it
+*/
+
+static inline void
+s3c2410_dma_buffdone(s3c2410_dma_chan_t *chan, s3c2410_dma_buf_t *buf,
+		     s3c2410_dma_buffresult_t result)
+{
+	pr_debug("callback_fn=%p, buf=%p, id=%p, size=%d, result=%d\n",
+		 chan->callback_fn, buf, buf->id, buf->size, result);
+
+	if (chan->callback_fn != NULL) {
+		(chan->callback_fn)(chan, buf->id, buf->size, result);
+	}
+}
+
+/* s3c2410_dma_start
+ *
+ * start a dma channel going
+*/
+
+static int s3c2410_dma_start(s3c2410_dma_chan_t *chan)
+{
+	unsigned long tmp;
+	unsigned long flags;
+
+	pr_debug("s3c2410_start_dma: channel=%d\n", chan->number);
+
+	local_irq_save(flags);
+
+	if (chan->state == S3C2410_DMA_RUNNING) {
+		pr_debug("s3c2410_start_dma: already running (%d)\n", chan->state);
+		local_irq_restore(flags);
+		return 0;
+	}
+
+	chan->state = S3C2410_DMA_RUNNING;
+
+	/* check wether there is anything to load, and if not, see
+	 * if we can find anything to load
+	 */
+
+	if (chan->load_state == S3C2410_DMALOAD_NONE) {
+		if (chan->next == NULL) {
+			printk(KERN_ERR "dma%d: channel has nothing loaded\n",
+			       chan->number);
+			chan->state = S3C2410_DMA_IDLE;
+			local_irq_restore(flags);
+			return -EINVAL;
+		}
+
+		s3c2410_dma_loadbuffer(chan, chan->next);
+	}
+
+	dbg_showchan(chan);
+
+	/* enable the channel */
+
+	if (!chan->irq_enabled) {
+		enable_irq(chan->irq);
+		chan->irq_enabled = 1;
+	}
+
+	/* start the channel going */
+
+	tmp = dma_rdreg(chan, S3C2410_DMA_DMASKTRIG);
+	tmp &= ~S3C2410_DMASKTRIG_STOP;
+	tmp |= S3C2410_DMASKTRIG_ON;
+	dma_wrreg(chan, S3C2410_DMA_DMASKTRIG, tmp);
+
+	pr_debug("wrote %08lx to DMASKTRIG\n", tmp);
+
+#if 0
+	/* the dma buffer loads should take care of clearing the AUTO
+	 * reloading feature */
+	tmp = dma_rdreg(chan, S3C2410_DMA_DCON);
+	tmp &= ~S3C2410_DCON_NORELOAD;
+	dma_wrreg(chan, S3C2410_DMA_DCON, tmp);
+#endif
+
+	s3c2410_dma_call_op(chan, S3C2410_DMAOP_START);
+
+	dbg_showchan(chan);
+
+	local_irq_restore(flags);
+	return 0;
+}
+
+/* s3c2410_dma_canload
+ *
+ * work out if we can queue another buffer into the DMA engine
+*/
+
+static int
+s3c2410_dma_canload(s3c2410_dma_chan_t *chan)
+{
+	if (chan->load_state == S3C2410_DMALOAD_NONE ||
+	    chan->load_state == S3C2410_DMALOAD_1RUNNING)
+		return 1;
+
+	return 0;
+}
+
+
+/* s3c2410_dma_enqueue
+ *
+ * queue an given buffer for dma transfer.
+ *
+ * id         the device driver's id information for this buffer
+ * data       the physical address of the buffer data
+ * size       the size of the buffer in bytes
+ *
+ * If the channel is not running, then the flag S3C2410_DMAF_AUTOSTART
+ * is checked, and if set, the channel is started. If this flag isn't set,
+ * then an error will be returned.
+ *
+ * It is possible to queue more than one DMA buffer onto a channel at
+ * once, and the code will deal with the re-loading of the next buffer
+ * when necessary.
+*/
+
+int s3c2410_dma_enqueue(unsigned int channel, void *id,
+			dma_addr_t data, int size)
+{
+	s3c2410_dma_chan_t *chan = &s3c2410_chans[channel];
+	s3c2410_dma_buf_t *buf;
+	unsigned long flags;
+
+	check_channel(channel);
+
+	pr_debug("%s: id=%p, data=%08x, size=%d\n",
+		 __FUNCTION__, id, (unsigned int)data, size);
+
+	buf = (s3c2410_dma_buf_t *)kmalloc(sizeof(*buf), GFP_ATOMIC);
+	if (buf == NULL) {
+		pr_debug("%s: out of memory (%d alloc)\n",
+			 __FUNCTION__, sizeof(*buf));
+		return -ENOMEM;
+	}
+
+	pr_debug("%s: new buffer %p\n", __FUNCTION__, buf);
+
+	//dbg_showchan(chan);
+
+	buf->next  = NULL;
+	buf->data  = buf->ptr = data;
+	buf->size  = size;
+	buf->id    = id;
+	buf->magic = BUF_MAGIC;
+
+	local_irq_save(flags);
+
+	if (chan->curr == NULL) {
+		/* we've got nothing loaded... */
+		pr_debug("%s: buffer %p queued onto empty channel\n",
+			 __FUNCTION__, buf);
+
+		chan->curr = buf;
+		chan->end  = buf;
+		chan->next = NULL;
+	} else {
+		pr_debug("dma%d: %s: buffer %p queued onto non-empty channel\n",
+			 chan->number, __FUNCTION__, buf);
+
+		if (chan->end == NULL)
+			pr_debug("dma%d: %s: %p not empty, and chan->end==NULL?\n",
+				 chan->number, __FUNCTION__, chan);
+
+		chan->end->next = buf;
+		chan->end = buf;
+	}
+
+	/* if necessary, update the next buffer field */
+	if (chan->next == NULL)
+		chan->next = buf;
+
+	/* check to see if we can load a buffer */
+	if (chan->state == S3C2410_DMA_RUNNING) {
+		if (chan->load_state == S3C2410_DMALOAD_1LOADED && 1) {
+			if (s3c2410_dma_waitforload(chan, __LINE__) == 0) {
+				printk(KERN_ERR "dma%d: loadbuffer:"
+				       "timeout loading buffer\n",
+				       chan->number);
+				dbg_showchan(chan);
+				local_irq_restore(flags);
+				return -EINVAL;
+			}
+		}
+
+		while (s3c2410_dma_canload(chan) && chan->next != NULL) {
+			s3c2410_dma_loadbuffer(chan, chan->next);
+		}
+	} else if (chan->state == S3C2410_DMA_IDLE) {
+		if (chan->flags & S3C2410_DMAF_AUTOSTART) {
+			s3c2410_dma_ctrl(chan->number, S3C2410_DMAOP_START);
+		} else {
+			printk(KERN_DEBUG "dma%d: cannot load onto stopped channel'n", chan->number);
+			local_irq_restore(flags);
+			return -EINVAL;
+		}
+	}
+
+	local_irq_restore(flags);
+	return 0;
+}
+
+static inline void
+s3c2410_dma_freebuf(s3c2410_dma_buf_t *buf)
+{
+	int magicok = (buf->magic == BUF_MAGIC);
+
+	buf->magic = -1;
+
+	if (magicok) {
+		kfree(buf);
+	} else {
+		printk("s3c2410_dma_freebuf: buff %p with bad magic\n", buf);
+	}
+}
+
+/* s3c2410_dma_lastxfer
+ *
+ * called when the system is out of buffers, to ensure that the channel
+ * is prepared for shutdown.
+*/
+
+static inline void
+s3c2410_dma_lastxfer(s3c2410_dma_chan_t *chan)
+{
+	pr_debug("dma%d: s3c2410_dma_lastxfer: load_state %d\n",
+		 chan->number, chan->load_state);
+
+	switch (chan->load_state) {
+	case S3C2410_DMALOAD_NONE:
+		break;
+
+	case S3C2410_DMALOAD_1LOADED:
+		if (s3c2410_dma_waitforload(chan, __LINE__) == 0) {
+				/* flag error? */
+			printk(KERN_ERR "dma%d: timeout waiting for load\n",
+			       chan->number);
+			return;
+		}
+		break;
+
+	default:
+		pr_debug("dma%d: lastxfer: unhandled load_state %d with no next",
+			 chan->number, chan->load_state);
+		return;
+
+	}
+
+	/* hopefully this'll shut the damned thing up after the transfer... */
+	dma_wrreg(chan, S3C2410_DMA_DCON, chan->dcon | S3C2410_DCON_NORELOAD);
+}
+
+
+#define dmadbg2(x...)
+
+static irqreturn_t
+s3c2410_dma_irq(int irq, void *devpw, struct pt_regs *regs)
+{
+	s3c2410_dma_chan_t *chan = (s3c2410_dma_chan_t *)devpw;
+	s3c2410_dma_buf_t  *buf;
+
+	buf = chan->curr;
+
+	dbg_showchan(chan);
+
+	/* modify the channel state */
+
+	switch (chan->load_state) {
+	case S3C2410_DMALOAD_1RUNNING:
+		/* TODO - if we are running only one buffer, we probably
+		 * want to reload here, and then worry about the buffer
+		 * callback */
+
+		chan->load_state = S3C2410_DMALOAD_NONE;
+		break;
+
+	case S3C2410_DMALOAD_1LOADED:
+		/* iirc, we should go back to NONE loaded here, we
+		 * had a buffer, and it was never verified as being
+		 * loaded.
+		 */
+
+		chan->load_state = S3C2410_DMALOAD_NONE;
+		break;
+
+	case S3C2410_DMALOAD_1LOADED_1RUNNING:
+		/* we'll worry about checking to see if another buffer is
+		 * ready after we've called back the owner. This should
+		 * ensure we do not wait around too long for the DMA
+		 * engine to start the next transfer
+		 */
+
+		chan->load_state = S3C2410_DMALOAD_1LOADED;
+		break;
+
+	case S3C2410_DMALOAD_NONE:
+		printk(KERN_ERR "dma%d: IRQ with no loaded buffer?\n",
+		       chan->number);
+		break;
+
+	default:
+		printk(KERN_ERR "dma%d: IRQ in invalid load_state %d\n",
+		       chan->number, chan->load_state);
+		break;
+	}
+
+	if (buf != NULL) {
+		/* update the chain to make sure that if we load any more
+		 * buffers when we call the callback function, things should
+		 * work properly */
+
+		chan->curr = buf->next;
+		buf->next  = NULL;
+
+		if (buf->magic != BUF_MAGIC) {
+			printk(KERN_ERR "dma%d: %s: buf %p incorrect magic\n",
+			       chan->number, __FUNCTION__, buf);
+			return IRQ_HANDLED;
+		}
+
+		s3c2410_dma_buffdone(chan, buf, S3C2410_RES_OK);
+
+		/* free resouces */
+		s3c2410_dma_freebuf(buf);
+	} else {
+	}
+
+	if (chan->next != NULL) {
+		unsigned long flags;
+
+		switch (chan->load_state) {
+		case S3C2410_DMALOAD_1RUNNING:
+			/* don't need to do anything for this state */
+			break;
+
+		case S3C2410_DMALOAD_NONE:
+			/* can load buffer immediately */
+			break;
+
+		case S3C2410_DMALOAD_1LOADED:
+			if (s3c2410_dma_waitforload(chan, __LINE__) == 0) {
+				/* flag error? */
+				printk(KERN_ERR "dma%d: timeout waiting for load\n",
+				       chan->number);
+				return IRQ_HANDLED;
+			}
+
+			break;
+
+		default:
+			printk(KERN_ERR "dma%d: unknown load_state in irq, %d\n",
+			       chan->number, chan->load_state);
+			return IRQ_HANDLED;
+		}
+
+		local_irq_save(flags);
+		s3c2410_dma_loadbuffer(chan, chan->next);
+		local_irq_restore(flags);
+	} else {
+		s3c2410_dma_lastxfer(chan);
+
+		/* see if we can stop this channel.. */
+		if (chan->load_state == S3C2410_DMALOAD_NONE) {
+			pr_debug("dma%d: end of transfer, stopping channel (%ld)\n",
+				 chan->number, jiffies);
+			s3c2410_dma_ctrl(chan->number, S3C2410_DMAOP_STOP);
+		}
+	}
+
+	return IRQ_HANDLED;
+}
+
+
+
+/* s3c2410_request_dma
+ *
+ * get control of an dma channel
+*/
+
+int s3c2410_dma_request(unsigned int channel, s3c2410_dma_client_t *client,
+			void *dev)
+{
+	s3c2410_dma_chan_t *chan = &s3c2410_chans[channel];
+	unsigned long flags;
+	int err;
+
+	pr_debug("dma%d: s3c2410_request_dma: client=%s, dev=%p\n",
+		 channel, client->name, dev);
+
+	check_channel(channel);
+
+	local_irq_save(flags);
+
+	dbg_showchan(chan);
+
+	if (chan->in_use) {
+		if (client != chan->client) {
+			printk(KERN_ERR "dma%d: already in use\n", channel);
+			local_irq_restore(flags);
+			return -EBUSY;
+		} else {
+			printk(KERN_ERR "dma%d: client already has channel\n", channel);
+		}
+	}
+
+	chan->client = client;
+	chan->in_use = 1;
+
+	if (!chan->irq_claimed) {
+		pr_debug("dma%d: %s : requesting irq %d\n",
+			 channel, __FUNCTION__, chan->irq);
+
+		err = request_irq(chan->irq, s3c2410_dma_irq, SA_INTERRUPT,
+				  client->name, (void *)chan);
+
+		if (err) {
+			chan->in_use = 0;
+			local_irq_restore(flags);
+
+			printk(KERN_ERR "%s: cannot get IRQ %d for DMA %d\n",
+			       client->name, chan->irq, chan->number);
+			return err;
+		}
+
+		chan->irq_claimed = 1;
+		chan->irq_enabled = 1;
+	}
+
+	local_irq_restore(flags);
+
+	/* need to setup */
+
+	pr_debug("%s: channel initialised, %p\n", __FUNCTION__, chan);
+
+	return 0;
+}
+
+/* s3c2410_dma_free
+ *
+ * release the given channel back to the system, will stop and flush
+ * any outstanding transfers, and ensure the channel is ready for the
+ * next claimant.
+ *
+ * Note, although a warning is currently printed if the freeing client
+ * info is not the same as the registrant's client info, the free is still
+ * allowed to go through.
+*/
+
+int s3c2410_dma_free(dmach_t channel, s3c2410_dma_client_t *client)
+{
+	s3c2410_dma_chan_t *chan = &s3c2410_chans[channel];
+	unsigned long flags;
+
+	check_channel(channel);
+
+	local_irq_save(flags);
+
+
+	if (chan->client != client) {
+		printk(KERN_WARNING "dma%d: possible free from different client (channel %p, passed %p)\n",
+		       channel, chan->client, client);
+	}
+
+	/* sort out stopping and freeing the channel */
+
+	if (chan->state != S3C2410_DMA_IDLE) {
+		pr_debug("%s: need to stop dma channel %p\n",
+		       __FUNCTION__, chan);
+
+		/* possibly flush the channel */
+		s3c2410_dma_ctrl(channel, S3C2410_DMAOP_STOP);
+	}
+
+	chan->client = NULL;
+	chan->in_use = 0;
+
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+static int s3c2410_dma_dostop(s3c2410_dma_chan_t *chan)
+{
+	unsigned long tmp;
+	unsigned long flags;
+
+	pr_debug("%s:\n", __FUNCTION__);
+
+	dbg_showchan(chan);
+
+	local_irq_save(flags);
+
+	s3c2410_dma_call_op(chan,  S3C2410_DMAOP_STOP);
+
+	tmp = dma_rdreg(chan, S3C2410_DMA_DMASKTRIG);
+	tmp |= S3C2410_DMASKTRIG_STOP;
+	dma_wrreg(chan, S3C2410_DMA_DMASKTRIG, tmp);
+
+#if 0
+	/* should also clear interrupts, according to WinCE BSP */
+	tmp = dma_rdreg(chan, S3C2410_DMA_DCON);
+	tmp |= S3C2410_DCON_NORELOAD;
+	dma_wrreg(chan, S3C2410_DMA_DCON, tmp);
+#endif
+
+	chan->state      = S3C2410_DMA_IDLE;
+	chan->load_state = S3C2410_DMALOAD_NONE;
+
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+/* s3c2410_dma_flush
+ *
+ * stop the channel, and remove all current and pending transfers
+*/
+
+static int s3c2410_dma_flush(s3c2410_dma_chan_t *chan)
+{
+	s3c2410_dma_buf_t *buf, *next;
+	unsigned long flags;
+
+	pr_debug("%s:\n", __FUNCTION__);
+
+	local_irq_save(flags);
+
+	if (chan->state != S3C2410_DMA_IDLE) {
+		pr_debug("%s: stopping channel...\n", __FUNCTION__ );
+		s3c2410_dma_ctrl(chan->number, S3C2410_DMAOP_STOP);
+	}
+
+	buf = chan->curr;
+	if (buf == NULL)
+		buf = chan->next;
+
+	chan->curr = chan->next = chan->end = NULL;
+
+	if (buf != NULL) {
+		for ( ; buf != NULL; buf = next) {
+			next = buf->next;
+
+			pr_debug("%s: free buffer %p, next %p\n",
+			       __FUNCTION__, buf, buf->next);
+
+			s3c2410_dma_buffdone(chan, buf, S3C2410_RES_ABORT);
+			s3c2410_dma_freebuf(buf);
+		}
+	}
+
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+
+int
+s3c2410_dma_ctrl(dmach_t channel, s3c2410_chan_op_t op)
+{
+	s3c2410_dma_chan_t *chan = &s3c2410_chans[channel];
+
+	check_channel(channel);
+
+	switch (op) {
+	case S3C2410_DMAOP_START:
+		return s3c2410_dma_start(chan);
+
+	case S3C2410_DMAOP_STOP:
+		return s3c2410_dma_dostop(chan);
+
+	case S3C2410_DMAOP_PAUSE:
+		return -ENOENT;
+
+	case S3C2410_DMAOP_RESUME:
+		return -ENOENT;
+
+	case S3C2410_DMAOP_FLUSH:
+		return s3c2410_dma_flush(chan);
+
+	case S3C2410_DMAOP_TIMEOUT:
+		return 0;
+
+	}
+
+	return -ENOENT;      /* unknown, don't bother */
+}
+
+
+/* DMA configuration for each channel
+ *
+ * DISRCC -> source of the DMA (AHB,APB)
+ * DISRC  -> source address of the DMA
+ * DIDSTC -> destination of the DMA (AHB,APD)
+ * DIDST  -> destination address of the DMA
+*/
+
+/* s3c2410_dma_config
+ *
+ * xfersize:     size of unit in bytes (1,2,4)
+ * dcon:         base value of the DCONx register
+*/
+
+int s3c2410_dma_config(dmach_t channel,
+		       int xferunit,
+		       int dcon)
+{
+	s3c2410_dma_chan_t *chan = &s3c2410_chans[channel];
+
+	pr_debug("%s: chan=%d, xfer_unit=%d, dcon=%08x\n",
+		 __FUNCTION__, channel, xferunit, dcon);
+
+	check_channel(channel);
+
+	switch (xferunit) {
+	case 1:
+		dcon |= S3C2410_DCON_BYTE;
+		break;
+
+	case 2:
+		dcon |= S3C2410_DCON_HALFWORD;
+		break;
+
+	case 4:
+		dcon |= S3C2410_DCON_WORD;
+		break;
+
+	default:
+		pr_debug("%s: bad transfer size %d\n", __FUNCTION__, xferunit);
+		return -EINVAL;
+	}
+
+	dcon |= S3C2410_DCON_HWTRIG;
+	dcon |= S3C2410_DCON_INTREQ;
+
+	pr_debug("%s: dcon now %08x\n", __FUNCTION__, dcon);
+
+	chan->dcon = dcon;
+	chan->xfer_unit = xferunit;
+
+	return 0;
+}
+
+
+int s3c2410_dma_setflags(dmach_t channel, unsigned int flags)
+{
+	s3c2410_dma_chan_t *chan = &s3c2410_chans[channel];
+
+	check_channel(channel);
+
+	pr_debug("%s: chan=%p, flags=%08x\n", __FUNCTION__, chan, flags);
+
+	chan->flags = flags;
+
+	return 0;
+}
+
+/* do we need to protect the settings of the fields from
+ * irq?
+*/
+
+int s3c2410_dma_set_opfn(dmach_t channel, s3c2410_dma_opfn_t rtn)
+{
+	s3c2410_dma_chan_t *chan = &s3c2410_chans[channel];
+
+	check_channel(channel);
+
+	pr_debug("%s: chan=%p, op rtn=%p\n", __FUNCTION__, chan, rtn);
+
+	chan->op_fn = rtn;
+
+	return 0;
+}
+
+int s3c2410_dma_set_buffdone_fn(dmach_t channel, s3c2410_dma_cbfn_t rtn)
+{
+	s3c2410_dma_chan_t *chan = &s3c2410_chans[channel];
+
+	check_channel(channel);
+
+	pr_debug("%s: chan=%p, callback rtn=%p\n", __FUNCTION__, chan, rtn);
+
+	chan->callback_fn = rtn;
+
+	return 0;
+}
+
+/* s3c2410_dma_devconfig
+ *
+ * configure the dma source/destination hardware type and address
+ *
+ * source:    S3C2410_DMASRC_HW: source is hardware
+ *            S3C2410_DMASRC_MEM: source is memory
+ *
+ * hwcfg:     the value for xxxSTCn register,
+ *            bit 0: 0=increment pointer, 1=leave pointer
+ *            bit 1: 0=soucre is AHB, 1=soucre is APB
+ *
+ * devaddr:   physical address of the source
+*/
+
+int s3c2410_dma_devconfig(int channel,
+			  s3c2410_dmasrc_t source,
+			  int hwcfg,
+			  unsigned long devaddr)
+{
+	s3c2410_dma_chan_t *chan = &s3c2410_chans[channel];
+
+	check_channel(channel);
+
+	pr_debug("%s: source=%d, hwcfg=%08x, devaddr=%08lx\n",
+		 __FUNCTION__, (int)source, hwcfg, devaddr);
+
+	chan->source = source;
+	chan->dev_addr = devaddr;
+
+	switch (source) {
+	case S3C2410_DMASRC_HW:
+		/* source is hardware */
+		pr_debug("%s: hw source, devaddr=%08lx, hwcfg=%d\n",
+			 __FUNCTION__, devaddr, hwcfg);
+		dma_wrreg(chan, S3C2410_DMA_DISRCC, hwcfg & 3);
+		dma_wrreg(chan, S3C2410_DMA_DISRC,  devaddr);
+		dma_wrreg(chan, S3C2410_DMA_DIDSTC, (0<<1) | (0<<0));
+
+		chan->addr_reg = dma_regaddr(chan, S3C2410_DMA_DIDST);
+		return 0;
+
+	case S3C2410_DMASRC_MEM:
+		/* source is memory */
+		pr_debug( "%s: mem source, devaddr=%08lx, hwcfg=%d\n",
+			  __FUNCTION__, devaddr, hwcfg);
+		dma_wrreg(chan, S3C2410_DMA_DISRCC, (0<<1) | (0<<0));
+		dma_wrreg(chan, S3C2410_DMA_DIDST,  devaddr);
+		dma_wrreg(chan, S3C2410_DMA_DIDSTC, hwcfg & 3);
+
+		chan->addr_reg = dma_regaddr(chan, S3C2410_DMA_DISRC);
+		return 0;
+	}
+
+	printk(KERN_ERR "dma%d: invalid source type (%d)\n", channel, source);
+	return -EINVAL;
+}
+
+/* initialisation code */
+
+static int __init s3c2410_init_dma(void)
+{
+	int channel;
+	s3c2410_dma_chan_t *cp;
+
+	printk("S3C2410 DMA Driver, (c) 2003-2004 Simtec Electronics\n");
+
+	dma_base = ioremap(S3C2410_PA_DMA, 0x200);
+	if (dma_base == NULL) {
+		printk(KERN_ERR "dma failed to remap register block\n");
+		return -ENOMEM;
+	}
+
+	for (channel = 0; channel < S3C2410_DMA_CHANNELS; channel++) {
+		cp = &s3c2410_chans[channel];
+
+		memset(cp, 0, sizeof(s3c2410_dma_chan_t));
+
+		/* dma channel irqs are in order.. */
+		cp->number = channel;
+		cp->irq    = channel + IRQ_DMA0;
+		cp->regs   = (unsigned long)dma_base + (channel*0x40);
+
+		/* point current stats somewhere */
+		cp->stats  = &cp->stats_store;
+		cp->stats_store.timeout_shortest = LONG_MAX;
+
+		/* basic channel configuration */
+
+		cp->load_timeout = 1<<18;
+
+		printk("DMA channel %d at %08lx, irq %d\n",
+		       cp->number, cp->regs, cp->irq);
+	}
+
+	return 0;
+}
+
+__initcall(s3c2410_init_dma);