1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * arch/arm/plat-spear/pl080.c
 4 *
 5 * DMAC pl080 definitions for SPEAr platform
 6 *
 7 * Copyright (C) 2012 ST Microelectronics
 8 * Viresh Kumar <vireshk@kernel.org>
 9 */
10
11#include <linux/amba/pl08x.h>
12#include <linux/amba/bus.h>
13#include <linux/bug.h>
14#include <linux/err.h>
15#include <linux/io.h>
16#include <linux/spinlock_types.h>
17#include "spear.h"
18#include "misc_regs.h"
19
20static spinlock_t lock = __SPIN_LOCK_UNLOCKED(x);
21
22struct {
23	unsigned char busy;
24	unsigned char val;
25} signals[16] = {{0, 0}, };
26
27int pl080_get_signal(const struct pl08x_channel_data *cd)
28{
29	unsigned int signal = cd->min_signal, val;
30	unsigned long flags;
31
32	spin_lock_irqsave(&lock, flags);
33
34	/* Return if signal is already acquired by somebody else */
35	if (signals[signal].busy &&
36			(signals[signal].val != cd->muxval)) {
37		spin_unlock_irqrestore(&lock, flags);
38		return -EBUSY;
39	}
40
41	/* If acquiring for the first time, configure it */
42	if (!signals[signal].busy) {
43		val = readl(DMA_CHN_CFG);
44
45		/*
46		 * Each request line has two bits in DMA_CHN_CFG register. To
47		 * goto the bits of current request line, do left shift of
48		 * value by 2 * signal number.
49		 */
50		val &= ~(0x3 << (signal * 2));
51		val |= cd->muxval << (signal * 2);
52		writel(val, DMA_CHN_CFG);
53	}
54
55	signals[signal].busy++;
56	signals[signal].val = cd->muxval;
57	spin_unlock_irqrestore(&lock, flags);
58
59	return signal;
60}
61
62void pl080_put_signal(const struct pl08x_channel_data *cd, int signal)
63{
64	unsigned long flags;
65
66	spin_lock_irqsave(&lock, flags);
67
68	/* if signal is not used */
69	if (!signals[signal].busy)
70		BUG();
71
72	signals[signal].busy--;
73
74	spin_unlock_irqrestore(&lock, flags);
75}