sh: G2 DMA IRQ and residue sampling.

This fixes a long-standing FIXME for G2 DMA, where we finally
wire up the IRQ handler and allow for sampling remaining bytes
while in-flight.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/drivers/dma/dma-g2.c

@@ -3,7 +3,7 @@
  *
  * G2 bus DMA support
  *
- * Copyright (C) 2003, 2004  Paul Mundt
+ * Copyright (C) 2003 - 2006  Paul Mundt
  *
  * This file is subject to the terms and conditions of the GNU General Public
  * License.  See the file "COPYING" in the main directory of this archive
@@ -13,7 +13,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/interrupt.h>
-
+#include <asm/cacheflush.h>
 #include <asm/mach/sysasic.h>
 #include <asm/mach/dma.h>
 #include <asm/dma.h>
@@ -47,17 +47,31 @@ struct g2_dma_info {
 
 static volatile struct g2_dma_info *g2_dma = (volatile struct g2_dma_info *)0xa05f7800;
 
+#define g2_bytes_remaining(i) \
+	((g2_dma->channel[i].size - \
+	  g2_dma->status[i].size) & 0x0fffffff)
+
 static irqreturn_t g2_dma_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 {
-	/* FIXME: Do some meaningful completion work here.. */
-	return IRQ_HANDLED;
-}
+	int i;
 
-static struct irqaction g2_dma_irq = {
-	.name		= "g2 DMA handler",
-	.handler	= g2_dma_interrupt,
-	.flags		= IRQF_DISABLED,
-};
+	for (i = 0; i < G2_NR_DMA_CHANNELS; i++) {
+		if (g2_dma->status[i].status & 0x20000000) {
+			unsigned int bytes = g2_bytes_remaining(i);
+
+			if (likely(bytes == 0)) {
+				struct dma_info *info = dev_id;
+				struct dma_channel *chan = info->channels + i;
+
+				wake_up(&chan->wait_queue);
+
+				return IRQ_HANDLED;
+			}
+		}
+	}
+
+	return IRQ_NONE;
+}
 
 static int g2_enable_dma(struct dma_channel *chan)
 {
@@ -135,8 +149,14 @@ static int g2_xfer_dma(struct dma_channel *chan)
 	return 0;
 }
 
+static int g2_get_residue(struct dma_channel *chan)
+{
+	return g2_bytes_remaining(chan->chan);
+}
+
 static struct dma_ops g2_dma_ops = {
 	.xfer		= g2_xfer_dma,
+	.get_residue	= g2_get_residue,
 };
 
 static struct dma_info g2_dma_info = {
@@ -148,13 +168,22 @@ static struct dma_info g2_dma_info = {
 
 static int __init g2_dma_init(void)
 {
-	setup_irq(HW_EVENT_G2_DMA, &g2_dma_irq);
+	int ret;
+
+	ret = request_irq(HW_EVENT_G2_DMA, g2_dma_interrupt, IRQF_DISABLED,
+			  "g2 DMA handler", &g2_dma_info);
+	if (unlikely(ret))
+		return -EINVAL;
 
 	/* Magic */
 	g2_dma->wait_state	= 27;
 	g2_dma->magic		= 0x4659404f;
 
-	return register_dmac(&g2_dma_info);
+	ret = register_dmac(&g2_dma_info);
+	if (unlikely(ret != 0))
+		free_irq(HW_EVENT_G2_DMA, 0);
+
+	return ret;
 }
 
 static void __exit g2_dma_exit(void)
@@ -169,4 +198,3 @@ module_exit(g2_dma_exit);
 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
 MODULE_DESCRIPTION("G2 bus DMA driver");
 MODULE_LICENSE("GPL");
-