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