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 #include "pl080.h"
20
21 static spinlock_t lock = __SPIN_LOCK_UNLOCKED(x);
22
23 struct {
24 unsigned char busy;
25 unsigned char val;
26 } signals[16] = {{0, 0}, };
27
pl080_get_signal(const struct pl08x_channel_data * cd)28 int pl080_get_signal(const struct pl08x_channel_data *cd)
29 {
30 unsigned int signal = cd->min_signal, val;
31 unsigned long flags;
32
33 spin_lock_irqsave(&lock, flags);
34
35 /* Return if signal is already acquired by somebody else */
36 if (signals[signal].busy &&
37 (signals[signal].val != cd->muxval)) {
38 spin_unlock_irqrestore(&lock, flags);
39 return -EBUSY;
40 }
41
42 /* If acquiring for the first time, configure it */
43 if (!signals[signal].busy) {
44 val = readl(DMA_CHN_CFG);
45
46 /*
47 * Each request line has two bits in DMA_CHN_CFG register. To
48 * goto the bits of current request line, do left shift of
49 * value by 2 * signal number.
50 */
51 val &= ~(0x3 << (signal * 2));
52 val |= cd->muxval << (signal * 2);
53 writel(val, DMA_CHN_CFG);
54 }
55
56 signals[signal].busy++;
57 signals[signal].val = cd->muxval;
58 spin_unlock_irqrestore(&lock, flags);
59
60 return signal;
61 }
62
pl080_put_signal(const struct pl08x_channel_data * cd,int signal)63 void pl080_put_signal(const struct pl08x_channel_data *cd, int signal)
64 {
65 unsigned long flags;
66
67 spin_lock_irqsave(&lock, flags);
68
69 /* if signal is not used */
70 if (!signals[signal].busy)
71 BUG();
72
73 signals[signal].busy--;
74
75 spin_unlock_irqrestore(&lock, flags);
76 }
77