1 files changed, 348 insertions, 0 deletions
diff --git a/arch/arm/mach-sa1100/dma.c b/arch/arm/mach-sa1100/dma.c
new file mode 100644
index 0000000..be0e442
--- /dev/null
+++ b/arch/arm/mach-sa1100/dma.c
@@ -0,0 +1,348 @@
+/*
+ * arch/arm/kernel/dma-sa1100.c
+ *
+ * Support functions for the SA11x0 internal DMA channels.
+ *
+ * Copyright (C) 2000, 2001 by Nicolas Pitre
+ *
+ * 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.
+ */
+
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/spinlock.h>
+#include <linux/errno.h>
+
+#include <asm/system.h>
+#include <asm/irq.h>
+#include <asm/hardware.h>
+#include <asm/dma.h>
+
+
+#undef DEBUG
+#ifdef DEBUG
+#define DPRINTK( s, arg... )  printk( "dma<%p>: " s, regs , ##arg )
+#else
+#define DPRINTK( x... )
+#endif
+
+
+typedef struct {
+	const char *device_id;		/* device name */
+	u_long device;			/* this channel device, 0  if unused*/
+	dma_callback_t callback;	/* to call when DMA completes */
+	void *data;			/* ... with private data ptr */
+} sa1100_dma_t;
+
+static sa1100_dma_t dma_chan[SA1100_DMA_CHANNELS];
+
+static spinlock_t dma_list_lock;
+
+
+static irqreturn_t dma_irq_handler(int irq, void *dev_id, struct pt_regs *regs)
+{
+	dma_regs_t *dma_regs = dev_id;
+	sa1100_dma_t *dma = dma_chan + (((u_int)dma_regs >> 5) & 7);
+	int status = dma_regs->RdDCSR;
+
+	if (status & (DCSR_ERROR)) {
+		printk(KERN_CRIT "DMA on \"%s\" caused an error\n", dma->device_id);
+		dma_regs->ClrDCSR = DCSR_ERROR;
+	}
+
+	dma_regs->ClrDCSR = status & (DCSR_DONEA | DCSR_DONEB);
+	if (dma->callback) {
+		if (status & DCSR_DONEA)
+			dma->callback(dma->data);
+		if (status & DCSR_DONEB)
+			dma->callback(dma->data);
+	}
+	return IRQ_HANDLED;
+}
+
+
+/**
+ *	sa1100_request_dma - allocate one of the SA11x0's DMA chanels
+ *	@device: The SA11x0 peripheral targeted by this request
+ *	@device_id: An ascii name for the claiming device
+ *	@callback: Function to be called when the DMA completes
+ *	@data: A cookie passed back to the callback function
+ *	@dma_regs: Pointer to the location of the allocated channel's identifier
+ *
+ * 	This function will search for a free DMA channel and returns the
+ * 	address of the hardware registers for that channel as the channel
+ * 	identifier. This identifier is written to the location pointed by
+ * 	@dma_regs. The list of possible values for @device are listed into
+ * 	linux/include/asm-arm/arch-sa1100/dma.h as a dma_device_t enum.
+ *
+ * 	Note that reading from a port and writing to the same port are
+ * 	actually considered as two different streams requiring separate
+ * 	DMA registrations.
+ *
+ * 	The @callback function is called from interrupt context when one
+ * 	of the two possible DMA buffers in flight has terminated. That
+ * 	function has to be small and efficient while posponing more complex
+ * 	processing to a lower priority execution context.
+ *
+ * 	If no channels are available, or if the desired @device is already in
+ * 	use by another DMA channel, then an error code is returned.  This
+ * 	function must be called before any other DMA calls.
+ **/
+
+int sa1100_request_dma (dma_device_t device, const char *device_id,
+			dma_callback_t callback, void *data,
+			dma_regs_t **dma_regs)
+{
+	sa1100_dma_t *dma = NULL;
+	dma_regs_t *regs;
+	int i, err;
+
+	*dma_regs = NULL;
+
+	err = 0;
+	spin_lock(&dma_list_lock);
+	for (i = 0; i < SA1100_DMA_CHANNELS; i++) {
+		if (dma_chan[i].device == device) {
+			err = -EBUSY;
+			break;
+		} else if (!dma_chan[i].device && !dma) {
+			dma = &dma_chan[i];
+		}
+	}
+	if (!err) {
+	       if (dma)
+		       dma->device = device;
+	       else
+		       err = -ENOSR;
+	}
+	spin_unlock(&dma_list_lock);
+	if (err)
+		return err;
+
+	i = dma - dma_chan;
+	regs = (dma_regs_t *)&DDAR(i);
+	err = request_irq(IRQ_DMA0 + i, dma_irq_handler, SA_INTERRUPT,
+			  device_id, regs);
+	if (err) {
+		printk(KERN_ERR
+		       "%s: unable to request IRQ %d for %s\n",
+		       __FUNCTION__, IRQ_DMA0 + i, device_id);
+		dma->device = 0;
+		return err;
+	}
+
+	*dma_regs = regs;
+	dma->device_id = device_id;
+	dma->callback = callback;
+	dma->data = data;
+
+	regs->ClrDCSR =
+		(DCSR_DONEA | DCSR_DONEB | DCSR_STRTA | DCSR_STRTB |
+		 DCSR_IE | DCSR_ERROR | DCSR_RUN);
+	regs->DDAR = device;
+
+	return 0;
+}
+
+
+/**
+ * 	sa1100_free_dma - free a SA11x0 DMA channel
+ * 	@regs: identifier for the channel to free
+ *
+ * 	This clears all activities on a given DMA channel and releases it
+ * 	for future requests.  The @regs identifier is provided by a
+ * 	successful call to sa1100_request_dma().
+ **/
+
+void sa1100_free_dma(dma_regs_t *regs)
+{
+	int i;
+
+	for (i = 0; i < SA1100_DMA_CHANNELS; i++)
+		if (regs == (dma_regs_t *)&DDAR(i))
+			break;
+	if (i >= SA1100_DMA_CHANNELS) {
+		printk(KERN_ERR "%s: bad DMA identifier\n", __FUNCTION__);
+		return;
+	}
+
+	if (!dma_chan[i].device) {
+		printk(KERN_ERR "%s: Trying to free free DMA\n", __FUNCTION__);
+		return;
+	}
+
+	regs->ClrDCSR =
+		(DCSR_DONEA | DCSR_DONEB | DCSR_STRTA | DCSR_STRTB |
+		 DCSR_IE | DCSR_ERROR | DCSR_RUN);
+	free_irq(IRQ_DMA0 + i, regs);
+	dma_chan[i].device = 0;
+}
+
+
+/**
+ * 	sa1100_start_dma - submit a data buffer for DMA
+ * 	@regs: identifier for the channel to use
+ * 	@dma_ptr: buffer physical (or bus) start address
+ * 	@size: buffer size
+ *
+ * 	This function hands the given data buffer to the hardware for DMA
+ * 	access. If another buffer is already in flight then this buffer
+ * 	will be queued so the DMA engine will switch to it automatically
+ * 	when the previous one is done.  The DMA engine is actually toggling
+ * 	between two buffers so at most 2 successful calls can be made before
+ * 	one of them terminates and the callback function is called.
+ *
+ * 	The @regs identifier is provided by a successful call to
+ * 	sa1100_request_dma().
+ *
+ * 	The @size must not be larger than %MAX_DMA_SIZE.  If a given buffer
+ * 	is larger than that then it's the caller's responsibility to split
+ * 	it into smaller chunks and submit them separately. If this is the
+ * 	case then a @size of %CUT_DMA_SIZE is recommended to avoid ending
+ * 	up with too small chunks. The callback function can be used to chain
+ * 	submissions of buffer chunks.
+ *
+ * 	Error return values:
+ * 	%-EOVERFLOW:	Given buffer size is too big.
+ * 	%-EBUSY:	Both DMA buffers are already in use.
+ * 	%-EAGAIN:	Both buffers were busy but one of them just completed
+ * 			but the interrupt handler has to execute first.
+ *
+ * 	This function returs 0 on success.
+ **/
+
+int sa1100_start_dma(dma_regs_t *regs, dma_addr_t dma_ptr, u_int size)
+{
+	unsigned long flags;
+	u_long status;
+	int ret;
+
+	if (dma_ptr & 3)
+		printk(KERN_WARNING "DMA: unaligned start address (0x%08lx)\n",
+		       (unsigned long)dma_ptr);
+
+	if (size > MAX_DMA_SIZE)
+		return -EOVERFLOW;
+
+	local_irq_save(flags);
+	status = regs->RdDCSR;
+
+	/* If both DMA buffers are started, there's nothing else we can do. */
+	if ((status & (DCSR_STRTA | DCSR_STRTB)) == (DCSR_STRTA | DCSR_STRTB)) {
+		DPRINTK("start: st %#x busy\n", status);
+		ret = -EBUSY;
+		goto out;
+	}
+
+	if (((status & DCSR_BIU) && (status & DCSR_STRTB)) ||
+	    (!(status & DCSR_BIU) && !(status & DCSR_STRTA))) {
+		if (status & DCSR_DONEA) {
+			/* give a chance for the interrupt to be processed */
+			ret = -EAGAIN;
+			goto out;
+		}
+		regs->DBSA = dma_ptr;
+		regs->DBTA = size;
+		regs->SetDCSR = DCSR_STRTA | DCSR_IE | DCSR_RUN;
+		DPRINTK("start a=%#x s=%d on A\n", dma_ptr, size);
+	} else {
+		if (status & DCSR_DONEB) {
+			/* give a chance for the interrupt to be processed */
+			ret = -EAGAIN;
+			goto out;
+		}
+		regs->DBSB = dma_ptr;
+		regs->DBTB = size;
+		regs->SetDCSR = DCSR_STRTB | DCSR_IE | DCSR_RUN;
+		DPRINTK("start a=%#x s=%d on B\n", dma_ptr, size);
+	}
+	ret = 0;
+
+out:
+	local_irq_restore(flags);
+	return ret;
+}
+
+
+/**
+ * 	sa1100_get_dma_pos - return current DMA position
+ * 	@regs: identifier for the channel to use
+ *
+ * 	This function returns the current physical (or bus) address for the
+ * 	given DMA channel.  If the channel is running i.e. not in a stopped
+ * 	state then the caller must disable interrupts prior calling this
+ * 	function and process the returned value before re-enabling them to
+ * 	prevent races with the completion interrupt handler and the callback
+ * 	function. The validation of the returned value is the caller's
+ * 	responsibility as well -- the hardware seems to return out of range
+ * 	values when the DMA engine completes a buffer.
+ *
+ * 	The @regs identifier is provided by a successful call to
+ * 	sa1100_request_dma().
+ **/
+
+dma_addr_t sa1100_get_dma_pos(dma_regs_t *regs)
+{
+	int status;
+
+	/*
+	 * We must determine whether buffer A or B is active.
+	 * Two possibilities: either we are in the middle of
+	 * a buffer, or the DMA controller just switched to the
+	 * next toggle but the interrupt hasn't been serviced yet.
+	 * The former case is straight forward.  In the later case,
+	 * we'll do like if DMA is just at the end of the previous
+	 * toggle since all registers haven't been reset yet.
+	 * This goes around the edge case and since we're always
+	 * a little behind anyways it shouldn't make a big difference.
+	 * If DMA has been stopped prior calling this then the
+	 * position is exact.
+	 */
+	status = regs->RdDCSR;
+	if ((!(status & DCSR_BIU) &&  (status & DCSR_STRTA)) ||
+	    ( (status & DCSR_BIU) && !(status & DCSR_STRTB)))
+		return regs->DBSA;
+	else
+		return regs->DBSB;
+}
+
+
+/**
+ * 	sa1100_reset_dma - reset a DMA channel
+ * 	@regs: identifier for the channel to use
+ *
+ * 	This function resets and reconfigure the given DMA channel. This is
+ * 	particularly useful after a sleep/wakeup event.
+ *
+ * 	The @regs identifier is provided by a successful call to
+ * 	sa1100_request_dma().
+ **/
+
+void sa1100_reset_dma(dma_regs_t *regs)
+{
+	int i;
+
+	for (i = 0; i < SA1100_DMA_CHANNELS; i++)
+		if (regs == (dma_regs_t *)&DDAR(i))
+			break;
+	if (i >= SA1100_DMA_CHANNELS) {
+		printk(KERN_ERR "%s: bad DMA identifier\n", __FUNCTION__);
+		return;
+	}
+
+	regs->ClrDCSR =
+		(DCSR_DONEA | DCSR_DONEB | DCSR_STRTA | DCSR_STRTB |
+		 DCSR_IE | DCSR_ERROR | DCSR_RUN);
+	regs->DDAR = dma_chan[i].device;
+}
+
+
+EXPORT_SYMBOL(sa1100_request_dma);
+EXPORT_SYMBOL(sa1100_free_dma);
+EXPORT_SYMBOL(sa1100_start_dma);
+EXPORT_SYMBOL(sa1100_get_dma_pos);
+EXPORT_SYMBOL(sa1100_reset_dma);
+