/*
 * arch/sh/drivers/dma/dma-g2.c
 *
 * G2 bus DMA support
 *
 * Copyright (C) 2003  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
 * for more details.
 */
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>

#include <asm/mach/sysasic.h>
#include <asm/mach/dma.h>
#include <asm/dma.h>

struct g2_channel {
	unsigned long g2_addr;		/* G2 bus address */
	unsigned long root_addr;	/* Root bus (SH-4) address */
	unsigned long size;		/* Size (in bytes), 32-byte aligned */
	unsigned long direction;	/* Transfer direction */
	unsigned long ctrl;		/* Transfer control */
	unsigned long chan_enable;	/* Channel enable */
	unsigned long xfer_enable;	/* Transfer enable */
	unsigned long xfer_stat;	/* Transfer status */
} __attribute__ ((aligned(32)));

struct g2_status {
	unsigned long g2_addr;
	unsigned long root_addr;
	unsigned long size;
	unsigned long status;
} __attribute__ ((aligned(16)));

struct g2_dma_info {
	struct g2_channel channel[G2_NR_DMA_CHANNELS];
	unsigned long pad1[G2_NR_DMA_CHANNELS];
	unsigned long wait_state;
	unsigned long pad2[10];
	unsigned long magic;
	struct g2_status status[G2_NR_DMA_CHANNELS];
} __attribute__ ((aligned(256)));

static volatile struct g2_dma_info *g2_dma = (volatile struct g2_dma_info *)0xa05f7800;

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;
}

static struct irqaction g2_dma_irq = {
	.name		= "g2 DMA handler",
	.handler	= g2_dma_interrupt,
	.flags		= SA_INTERRUPT,
};

static int g2_enable_dma(struct dma_info *info)
{
	unsigned int chan = info->chan;

	g2_dma->channel[chan].chan_enable = 1;
	g2_dma->channel[chan].xfer_enable = 1;

	return 0;
}

static int g2_disable_dma(struct dma_info *info)
{
	unsigned int chan = info->chan;

	g2_dma->channel[chan].chan_enable = 0;
	g2_dma->channel[chan].xfer_enable = 0;

	return 0;
}

static int g2_xfer_dma(struct dma_info *info)
{
	unsigned int chan = info->chan;

	if (info->sar & 31) {
		printk("g2dma: unaligned source 0x%lx\n", info->sar);
		return -EINVAL;
	}

	if (info->dar & 31) {
		printk("g2dma: unaligned dest 0x%lx\n", info->dar);
		return -EINVAL;
	}

	/* Align the count */
	if (info->count & 31)
		info->count = (info->count + (32 - 1)) & ~(32 - 1);

	/* Fixup destination */
	info->dar += 0xa0800000;

	/* Fixup direction */
	info->mode = !info->mode;

	flush_icache_range((unsigned long)info->sar, info->count);

	g2_disable_dma(info);

	g2_dma->channel[chan].g2_addr	= info->dar & 0x1fffffe0;
	g2_dma->channel[chan].root_addr = info->sar & 0x1fffffe0;
	g2_dma->channel[chan].size	= (info->count & ~31) | 0x80000000;
	g2_dma->channel[chan].direction = info->mode;

	/*
	 * bit 0 - ???
	 * bit 1 - if set, generate a hardware event on transfer completion
	 * bit 2 - ??? something to do with suspend?
	 */
	g2_dma->channel[chan].ctrl	= 5; /* ?? */

	g2_enable_dma(info);
	
	/* debug cruft */
	pr_debug("count, sar, dar, mode, ctrl, chan, xfer: %ld, 0x%08lx, "
		 "0x%08lx, %ld, %ld, %ld, %ld\n",
		 g2_dma->channel[chan].size,
		 g2_dma->channel[chan].root_addr,
		 g2_dma->channel[chan].g2_addr,
		 g2_dma->channel[chan].direction,
		 g2_dma->channel[chan].ctrl,
		 g2_dma->channel[chan].chan_enable,
		 g2_dma->channel[chan].xfer_enable);

	return 0;
}

static struct dma_ops g2_dma_ops = {
	.name		= "G2 DMA",
	.xfer		= g2_xfer_dma,
};

static int __init g2_dma_init(void)
{
	int i, base;

	setup_irq(HW_EVENT_G2_DMA, &g2_dma_irq);

	/* Magic */
	g2_dma->wait_state	= 27;
	g2_dma->magic		= 0x4659404f;

	/* G2 channels come after on-chip and pvr2 */
	base = ONCHIP_NR_DMA_CHANNELS + PVR2_NR_DMA_CHANNELS;

	for (i = 0; i < G2_NR_DMA_CHANNELS; i++)
		dma_info[base + i].ops = &g2_dma_ops;
	
	return register_dmac(&g2_dma_ops);
}

static void __exit g2_dma_exit(void)
{
	free_irq(HW_EVENT_G2_DMA, 0);
}

subsys_initcall(g2_dma_init);
module_exit(g2_dma_exit);

MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
MODULE_DESCRIPTION("G2 bus DMA driver");
MODULE_LICENSE("GPL");