[ARM] pxa: introduce plat-pxa for PXA common code and add DMA support

1. introduce folder of 'arch/arm/plat-pxa' for common code across different
   PXA processor families

2. initially moved DMA code into plat-pxa

3. common code in <mach/dma.h> moved into <plat/dma.h>, new processors
   should implement its own <mach/dma.h>, provide the following required
   definitions and '#include <plat/dma.h>' in the end:

   - DMAC_REGS_VIRT for mapped virtual address of the DMA registers'
     physical I/O memory

Signed-off-by: Eric Miao <eric.miao@marvell.com>

1 files changed, 144 insertions, 0 deletions

diff --git a/arch/arm/plat-pxa/dma.c b/arch/arm/plat-pxa/dma.c
new file mode 100644
index 0000000..70aeee4
--- /dev/null
+++ b/arch/arm/plat-pxa/dma.c
@@ -0,0 +1,144 @@
+/*
+ *  linux/arch/arm/plat-pxa/dma.c
+ *
+ *  PXA DMA registration and IRQ dispatching
+ *
+ *  Author:	Nicolas Pitre
+ *  Created:	Nov 15, 2001
+ *  Copyright:	MontaVista Software Inc.
+ *
+ *  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/init.h>
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/errno.h>
+
+#include <asm/system.h>
+#include <asm/irq.h>
+#include <mach/hardware.h>
+#include <mach/dma.h>
+
+struct dma_channel {
+	char *name;
+	pxa_dma_prio prio;
+	void (*irq_handler)(int, void *);
+	void *data;
+};
+
+static struct dma_channel *dma_channels;
+static int num_dma_channels;
+
+int pxa_request_dma (char *name, pxa_dma_prio prio,
+			void (*irq_handler)(int, void *),
+			void *data)
+{
+	unsigned long flags;
+	int i, found = 0;
+
+	/* basic sanity checks */
+	if (!name || !irq_handler)
+		return -EINVAL;
+
+	local_irq_save(flags);
+
+	do {
+		/* try grabbing a DMA channel with the requested priority */
+		for (i = 0; i < num_dma_channels; i++) {
+			if ((dma_channels[i].prio == prio) &&
+			    !dma_channels[i].name) {
+				found = 1;
+				break;
+			}
+		}
+		/* if requested prio group is full, try a hier priority */
+	} while (!found && prio--);
+
+	if (found) {
+		DCSR(i) = DCSR_STARTINTR|DCSR_ENDINTR|DCSR_BUSERR;
+		dma_channels[i].name = name;
+		dma_channels[i].irq_handler = irq_handler;
+		dma_channels[i].data = data;
+	} else {
+		printk (KERN_WARNING "No more available DMA channels for %s\n", name);
+		i = -ENODEV;
+	}
+
+	local_irq_restore(flags);
+	return i;
+}
+
+void pxa_free_dma (int dma_ch)
+{
+	unsigned long flags;
+
+	if (!dma_channels[dma_ch].name) {
+		printk (KERN_CRIT
+			"%s: trying to free channel %d which is already freed\n",
+			__func__, dma_ch);
+		return;
+	}
+
+	local_irq_save(flags);
+	DCSR(dma_ch) = DCSR_STARTINTR|DCSR_ENDINTR|DCSR_BUSERR;
+	dma_channels[dma_ch].name = NULL;
+	local_irq_restore(flags);
+}
+
+static irqreturn_t dma_irq_handler(int irq, void *dev_id)
+{
+	int i, dint = DINT;
+
+	for (i = 0; i < num_dma_channels; i++) {
+		if (dint & (1 << i)) {
+			struct dma_channel *channel = &dma_channels[i];
+			if (channel->name && channel->irq_handler) {
+				channel->irq_handler(i, channel->data);
+			} else {
+				/*
+				 * IRQ for an unregistered DMA channel:
+				 * let's clear the interrupts and disable it.
+				 */
+				printk (KERN_WARNING "spurious IRQ for DMA channel %d\n", i);
+				DCSR(i) = DCSR_STARTINTR|DCSR_ENDINTR|DCSR_BUSERR;
+			}
+		}
+	}
+	return IRQ_HANDLED;
+}
+
+int __init pxa_init_dma(int irq, int num_ch)
+{
+	int i, ret;
+
+	dma_channels = kzalloc(sizeof(struct dma_channel) * num_ch, GFP_KERNEL);
+	if (dma_channels == NULL)
+		return -ENOMEM;
+
+	/* dma channel priorities on pxa2xx processors:
+	 * ch 0 - 3,  16 - 19  <--> (0) DMA_PRIO_HIGH
+	 * ch 4 - 7,  20 - 23  <--> (1) DMA_PRIO_MEDIUM
+	 * ch 8 - 15, 24 - 31  <--> (2) DMA_PRIO_LOW
+	 */
+	for (i = 0; i < num_ch; i++) {
+		DCSR(i) = 0;
+		dma_channels[i].prio = min((i & 0xf) >> 2, DMA_PRIO_LOW);
+	}
+
+	ret = request_irq(irq, dma_irq_handler, IRQF_DISABLED, "DMA", NULL);
+	if (ret) {
+		printk (KERN_CRIT "Wow!  Can't register IRQ for DMA\n");
+		kfree(dma_channels);
+		return ret;
+	}
+
+	num_dma_channels = num_ch;
+	return 0;
+}
+
+EXPORT_SYMBOL(pxa_request_dma);
+EXPORT_SYMBOL(pxa_free_dma);