[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

arch/arm/configs/s3c2410_defconfig

@@ -77,6 +77,12 @@ CONFIG_ARCH_H1940=y
 CONFIG_ARCH_SMDK2410=y
 CONFIG_MACH_VR1000=y
 
+#
+# S3C2410 Setup
+#
+CONFIG_S3C2410_DMA=y
+# CONFIG_S3C2410_DMA_DEBUG is not set
+
 #
 # Processor Type
 #
@@ -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
 
 #

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

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

arch/arm/mach-s3c2410/dma.c

+/* 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);

include/asm-arm/arch-s3c2410/dma.h

@@ -41,100 +41,250 @@
 /* we have 4 dma channels */
 #define S3C2410_DMA_CHANNELS        (4)
 
+/* types */
+
+typedef enum {
+	S3C2410_DMA_IDLE,
+	S3C2410_DMA_RUNNING,
+	S3C2410_DMA_PAUSED
+} s3c2410_dma_state_t;
+
+
+/* s3c2410_dma_loadst_t
+ *
+ * This represents the state of the DMA engine, wrt to the loaded / running
+ * transfers. Since we don't have any way of knowing exactly the state of
+ * the DMA transfers, we need to know the state to make decisions on wether
+ * we can
+ *
+ * S3C2410_DMA_NONE
+ *
+ * There are no buffers loaded (the channel should be inactive)
+ *
+ * S3C2410_DMA_1LOADED
+ *
+ * There is one buffer loaded, however it has not been confirmed to be
+ * loaded by the DMA engine. This may be because the channel is not
+ * yet running, or the DMA driver decided that it was too costly to
+ * sit and wait for it to happen.
+ *
+ * S3C2410_DMA_1RUNNING
+ *
+ * The buffer has been confirmed running, and not finisged
+ *
+ * S3C2410_DMA_1LOADED_1RUNNING
+ *
+ * There is a buffer waiting to be loaded by the DMA engine, and one
+ * currently running.
+*/
+
+typedef enum {
+	S3C2410_DMALOAD_NONE,
+	S3C2410_DMALOAD_1LOADED,
+	S3C2410_DMALOAD_1RUNNING,
+	S3C2410_DMALOAD_1LOADED_1RUNNING,
+} s3c2410_dma_loadst_t;
+
+typedef enum {
+	S3C2410_RES_OK,
+	S3C2410_RES_ERR,
+	S3C2410_RES_ABORT
+} s3c2410_dma_buffresult_t;
+
+
+typedef enum s3c2410_dmasrc_e s3c2410_dmasrc_t;
+
+enum s3c2410_dmasrc_e {
+	S3C2410_DMASRC_HW,      /* source is memory */
+	S3C2410_DMASRC_MEM      /* source is hardware */
+};
+
+/* enum s3c2410_chan_op_e
+ *
+ * operation codes passed to the DMA code by the user, and also used
+ * to inform the current channel owner of any changes to the system state
+*/
+
+enum s3c2410_chan_op_e {
+	S3C2410_DMAOP_START,
+	S3C2410_DMAOP_STOP,
+	S3C2410_DMAOP_PAUSE,
+	S3C2410_DMAOP_RESUME,
+	S3C2410_DMAOP_FLUSH,
+	S3C2410_DMAOP_TIMEOUT,           /* internal signal to handler */
+};
+
+typedef enum s3c2410_chan_op_e s3c2410_chan_op_t;
+
+/* flags */
+
+#define S3C2410_DMAF_SLOW         (1<<0)   /* slow, so don't worry about
+					    * waiting for reloads */
+#define S3C2410_DMAF_AUTOSTART    (1<<1)   /* auto-start if buffer queued */
 
 /* dma buffer */
 
 typedef struct s3c2410_dma_buf_s s3c2410_dma_buf_t;
 
+struct s3c2410_dma_client {
+	char                *name;
+};
+
+typedef struct s3c2410_dma_client s3c2410_dma_client_t;
+
+/* s3c2410_dma_buf_s
+ *
+ * internally used buffer structure to describe a queued or running
+ * buffer.
+*/
+
 struct s3c2410_dma_buf_s {
 	s3c2410_dma_buf_t   *next;
 	int                  magic;        /* magic */
 	int                  size;         /* buffer size in bytes */
 	dma_addr_t           data;         /* start of DMA data */
 	dma_addr_t           ptr;          /* where the DMA got to [1] */
-	int		     ref;
 	void                *id;           /* client's id */
-	unsigned char	     no_callback;  /* disable callback for buffer */
 };
 
 /* [1] is this updated for both recv/send modes? */
 
 typedef struct s3c2410_dma_chan_s s3c2410_dma_chan_t;
 
-typedef void (*s3c2410_dma_cbfn_t)(s3c2410_dma_chan_t *, void *buf, int size);
-typedef void (*s3c2410_dma_enfn_t)(s3c2410_dma_chan_t *, int on);
-typedef void (*s3c2410_dma_pausefn_t)(s3c2410_dma_chan_t *, int on);
+/* s3c2410_dma_cbfn_t
+ *
+ * buffer callback routine type
+*/
+
+typedef void (*s3c2410_dma_cbfn_t)(s3c2410_dma_chan_t *, void *buf, int size,
+				   s3c2410_dma_buffresult_t result);
+
+typedef int  (*s3c2410_dma_opfn_t)(s3c2410_dma_chan_t *,
+				   s3c2410_chan_op_t );
+
+struct s3c2410_dma_stats_s {
+	unsigned long          loads;
+	unsigned long          timeout_longest;
+	unsigned long          timeout_shortest;
+	unsigned long          timeout_avg;
+	unsigned long          timeout_failed;
+};
+
+typedef struct s3c2410_dma_stats_s s3c2410_dma_stats_t;
+
+/* struct s3c2410_dma_chan_s
+ *
+ * full state information for each DMA channel
+*/
 
 struct s3c2410_dma_chan_s {
-	/* channel state flags */
+	/* channel state flags and information */
 	unsigned char          number;      /* number of this dma channel */
 	unsigned char          in_use;      /* channel allocated */
-	unsigned char	       started;	      /* channel has been started */
-	unsigned char	       stopped;	      /* channel stopped */
-	unsigned char	       sleeping;
+	unsigned char          irq_claimed; /* irq claimed for channel */
+	unsigned char          irq_enabled; /* irq enabled for channel */
 	unsigned char          xfer_unit;   /* size of an transfer */
-	unsigned char	       irq_claimed;
+
+	/* channel state */
+
+	s3c2410_dma_state_t    state;
+	s3c2410_dma_loadst_t   load_state;
+	s3c2410_dma_client_t  *client;
+
+	/* channel configuration */
+	s3c2410_dmasrc_t       source;
+	unsigned long          dev_addr;
+	unsigned long          load_timeout;
+	unsigned int           flags;        /* channel flags */
 
 	/* channel's hardware position and configuration */
 	unsigned long          regs;         /* channels registers */
 	unsigned int           irq;          /* channel irq */
-	unsigned long	       addr_reg;      /* data address register for buffs */
+	unsigned long          addr_reg;     /* data address register */
 	unsigned long          dcon;         /* default value of DCON */
 
-	/* driver handlers for channel */
-	s3c2410_dma_cbfn_t     callback_fn;   /* callback function for buf-done */
-	s3c2410_dma_enfn_t     enable_fn;     /* channel enable function */
-	s3c2410_dma_pausefn_t  pause_fn;      /* channel pause function */
+	/* driver handles */
+	s3c2410_dma_cbfn_t     callback_fn;  /* buffer done callback */
+	s3c2410_dma_opfn_t     op_fn;        /* channel operation callback */
+
+	/* stats gathering */
+	s3c2410_dma_stats_t   *stats;
+	s3c2410_dma_stats_t    stats_store;
 
 	/* buffer list and information */
 	s3c2410_dma_buf_t      *curr;        /* current dma buffer */
 	s3c2410_dma_buf_t      *next;        /* next buffer to load */
 	s3c2410_dma_buf_t      *end;         /* end of queue */
-
-	int		       queue_count;   /* number of items in queue */
-	int		       loaded_count;  /* number of loaded buffers */
 };
 
-/* note, we don't really use dma_deivce_t at the moment */
+/* the currently allocated channel information */
+extern s3c2410_dma_chan_t s3c2410_chans[];
+
+/* note, we don't really use dma_device_t at the moment */
 typedef unsigned long dma_device_t;
 
-typedef enum s3c2410_dmasrc_e s3c2410_dmasrc_t;
+/* functions --------------------------------------------------------------- */
 
-/* these two defines control the source for the dma channel,
- * wether it is from memory or an device
+/* s3c2410_dma_request
+ *
+ * request a dma channel exclusivley
 */
 
-enum s3c2410_dmasrc_e {
-  S3C2410_DMASRC_HW,	  /* source is memory */
-  S3C2410_DMASRC_MEM	  /* source is hardware */
-};
+extern int s3c2410_dma_request(dmach_t channel,
+			       s3c2410_dma_client_t *, void *dev);
 
-/* dma control routines */
 
-extern int s3c2410_request_dma(dmach_t channel, const char *devid, void *dev);
-extern int s3c2410_free_dma(dmach_t channel);
-extern int s3c2410_dma_flush_all(dmach_t channel);
+/* s3c2410_dma_ctrl
+ *
+ * change the state of the dma channel
+*/
 
-extern int s3c2410_dma_stop(dmach_t channel);
-extern int s3c2410_dma_resume(dmach_t channel);
+extern int s3c2410_dma_ctrl(dmach_t channel, s3c2410_chan_op_t op);
 
-extern int s3c2410_dma_queue(dmach_t channel, void *id,
-			     dma_addr_t data, int size);
+/* s3c2410_dma_setflags
+ *
+ * set the channel's flags to a given state
+*/
 
-#define s3c2410_dma_queue_buffer s3c2410_dma_queue
+extern int s3c2410_dma_setflags(dmach_t channel,
+				unsigned int flags);
 
-/* channel configuration */
+/* s3c2410_dma_free
+ *
+ * free the dma channel (will also abort any outstanding operations)
+*/
+
+extern int s3c2410_dma_free(dmach_t channel, s3c2410_dma_client_t *);
+
+/* s3c2410_dma_enqueue
+ *
+ * place the given buffer onto the queue of operations for the channel.
+ * The buffer must be allocated from dma coherent memory, or the Dcache/WB
+ * drained before the buffer is given to the DMA system.
+*/
+
+extern int s3c2410_dma_enqueue(dmach_t channel, void *id,
+			       dma_addr_t data, int size);
+
+/* s3c2410_dma_config
+ *
+ * configure the dma channel
+*/
 
 extern int s3c2410_dma_config(dmach_t channel, int xferunit, int dcon);
 
+/* s3c2410_dma_devconfig
+ *
+ * configure the device we're talking to
+*/
+
 extern int s3c2410_dma_devconfig(int channel, s3c2410_dmasrc_t source,
 				 int hwcfg, unsigned long devaddr);
 
-extern int s3c2410_dma_set_enablefn(dmach_t, s3c2410_dma_enfn_t rtn);
-extern int s3c2410_dma_set_pausefn(dmach_t, s3c2410_dma_pausefn_t rtn);
-extern int s3c2410_dma_set_callbackfn(dmach_t, s3c2410_dma_cbfn_t rtn);
+extern int s3c2410_dma_set_opfn(dmach_t, s3c2410_dma_opfn_t rtn);
+extern int s3c2410_dma_set_buffdone_fn(dmach_t, s3c2410_dma_cbfn_t rtn);
 
-#define s3c2410_dma_set_callback s3c2410_dma_set_callbackfn
+/* DMA Register definitions */
 
 #define S3C2410_DMA_DISRC       (0x00)
 #define S3C2410_DMA_DISRCC      (0x04)
@@ -164,6 +314,7 @@ extern int s3c2410_dma_set_callbackfn(dmach_t, s3c2410_dma_cbfn_t rtn);
 #define S3C2410_DCON_WORD       (2<<20)
 
 #define S3C2410_DCON_AUTORELOAD (0<<22)
+#define S3C2410_DCON_NORELOAD   (1<<22)
 #define S3C2410_DCON_HWTRIG     (1<<23)
 
 #endif /* __ASM_ARCH_DMA_H */