1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * arch/sh/drivers/dma/dma-pvr2.c
4  *
5  * NEC PowerVR 2 (Dreamcast) DMA support
6  *
7  * Copyright (C) 2003, 2004  Paul Mundt
8  */
9 #include <linux/init.h>
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/interrupt.h>
13 #include <mach/sysasic.h>
14 #include <mach/dma.h>
15 #include <asm/dma.h>
16 #include <asm/io.h>
17 
18 static unsigned int xfer_complete;
19 static int count;
20 
pvr2_dma_interrupt(int irq,void * dev_id)21 static irqreturn_t pvr2_dma_interrupt(int irq, void *dev_id)
22 {
23 	if (get_dma_residue(PVR2_CASCADE_CHAN)) {
24 		printk(KERN_WARNING "DMA: SH DMAC did not complete transfer "
25 		       "on channel %d, waiting..\n", PVR2_CASCADE_CHAN);
26 		dma_wait_for_completion(PVR2_CASCADE_CHAN);
27 	}
28 
29 	if (count++ < 10)
30 		pr_debug("Got a pvr2 dma interrupt for channel %d\n",
31 			 irq - HW_EVENT_PVR2_DMA);
32 
33 	xfer_complete = 1;
34 
35 	return IRQ_HANDLED;
36 }
37 
pvr2_request_dma(struct dma_channel * chan)38 static int pvr2_request_dma(struct dma_channel *chan)
39 {
40 	if (__raw_readl(PVR2_DMA_MODE) != 0)
41 		return -EBUSY;
42 
43 	__raw_writel(0, PVR2_DMA_LMMODE0);
44 
45 	return 0;
46 }
47 
pvr2_get_dma_residue(struct dma_channel * chan)48 static int pvr2_get_dma_residue(struct dma_channel *chan)
49 {
50 	return xfer_complete == 0;
51 }
52 
pvr2_xfer_dma(struct dma_channel * chan)53 static int pvr2_xfer_dma(struct dma_channel *chan)
54 {
55 	if (chan->sar || !chan->dar)
56 		return -EINVAL;
57 
58 	xfer_complete = 0;
59 
60 	__raw_writel(chan->dar, PVR2_DMA_ADDR);
61 	__raw_writel(chan->count, PVR2_DMA_COUNT);
62 	__raw_writel(chan->mode & DMA_MODE_MASK, PVR2_DMA_MODE);
63 
64 	return 0;
65 }
66 
67 static struct dma_ops pvr2_dma_ops = {
68 	.request	= pvr2_request_dma,
69 	.get_residue	= pvr2_get_dma_residue,
70 	.xfer		= pvr2_xfer_dma,
71 };
72 
73 static struct dma_info pvr2_dma_info = {
74 	.name		= "pvr2_dmac",
75 	.nr_channels	= 1,
76 	.ops		= &pvr2_dma_ops,
77 	.flags		= DMAC_CHANNELS_TEI_CAPABLE,
78 };
79 
pvr2_dma_init(void)80 static int __init pvr2_dma_init(void)
81 {
82 	if (request_irq(HW_EVENT_PVR2_DMA, pvr2_dma_interrupt, 0,
83 			"pvr2 DMA handler", NULL))
84 		pr_err("Failed to register pvr2 DMA handler interrupt\n");
85 	request_dma(PVR2_CASCADE_CHAN, "pvr2 cascade");
86 
87 	return register_dmac(&pvr2_dma_info);
88 }
89 
pvr2_dma_exit(void)90 static void __exit pvr2_dma_exit(void)
91 {
92 	free_dma(PVR2_CASCADE_CHAN);
93 	free_irq(HW_EVENT_PVR2_DMA, 0);
94 	unregister_dmac(&pvr2_dma_info);
95 }
96 
97 subsys_initcall(pvr2_dma_init);
98 module_exit(pvr2_dma_exit);
99 
100 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
101 MODULE_DESCRIPTION("NEC PowerVR 2 DMA driver");
102 MODULE_LICENSE("GPL v2");
103