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
20 static spinlock_t lock = __SPIN_LOCK_UNLOCKED(x);
21
22 struct {
23 unsigned char busy;
24 unsigned char val;
25 } signals[16] = {{0, 0}, };
26
pl080_get_signal(const struct pl08x_channel_data * cd)27 int 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
pl080_put_signal(const struct pl08x_channel_data * cd,int signal)62 void 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 }
76