1 /*
2 * arch/arm/plat-spear/pl080.c
3 *
4 * DMAC pl080 definitions for SPEAr platform
5 *
6 * Copyright (C) 2012 ST Microelectronics
7 * Viresh Kumar <vireshk@kernel.org>
8 *
9 * This file is licensed under the terms of the GNU General Public
10 * License version 2. This program is licensed "as is" without any
11 * warranty of any kind, whether express or implied.
12 */
13
14 #include <linux/amba/pl08x.h>
15 #include <linux/amba/bus.h>
16 #include <linux/bug.h>
17 #include <linux/err.h>
18 #include <linux/io.h>
19 #include <linux/spinlock_types.h>
20 #include <mach/spear.h>
21 #include <mach/misc_regs.h>
22
23 static spinlock_t lock = __SPIN_LOCK_UNLOCKED(x);
24
25 struct {
26 unsigned char busy;
27 unsigned char val;
28 } signals[16] = {{0, 0}, };
29
pl080_get_signal(const struct pl08x_channel_data * cd)30 int pl080_get_signal(const struct pl08x_channel_data *cd)
31 {
32 unsigned int signal = cd->min_signal, val;
33 unsigned long flags;
34
35 spin_lock_irqsave(&lock, flags);
36
37 /* Return if signal is already acquired by somebody else */
38 if (signals[signal].busy &&
39 (signals[signal].val != cd->muxval)) {
40 spin_unlock_irqrestore(&lock, flags);
41 return -EBUSY;
42 }
43
44 /* If acquiring for the first time, configure it */
45 if (!signals[signal].busy) {
46 val = readl(DMA_CHN_CFG);
47
48 /*
49 * Each request line has two bits in DMA_CHN_CFG register. To
50 * goto the bits of current request line, do left shift of
51 * value by 2 * signal number.
52 */
53 val &= ~(0x3 << (signal * 2));
54 val |= cd->muxval << (signal * 2);
55 writel(val, DMA_CHN_CFG);
56 }
57
58 signals[signal].busy++;
59 signals[signal].val = cd->muxval;
60 spin_unlock_irqrestore(&lock, flags);
61
62 return signal;
63 }
64
pl080_put_signal(const struct pl08x_channel_data * cd,int signal)65 void pl080_put_signal(const struct pl08x_channel_data *cd, int signal)
66 {
67 unsigned long flags;
68
69 spin_lock_irqsave(&lock, flags);
70
71 /* if signal is not used */
72 if (!signals[signal].busy)
73 BUG();
74
75 signals[signal].busy--;
76
77 spin_unlock_irqrestore(&lock, flags);
78 }
79