xref: /openbmc/linux/arch/arm/mach-spear/pl080.c (revision 5e40c79a)
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