original development tree for Linux kernel GTP module; now long in mainline.
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linux-gtp/arch/arm/plat-spear/pl080.c

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1.9 KiB

/*
* arch/arm/plat-spear/pl080.c
*
* DMAC pl080 definitions for SPEAr platform
*
* Copyright (C) 2012 ST Microelectronics
* Viresh Kumar <viresh.linux@gmail.com>
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#include <linux/amba/pl08x.h>
#include <linux/amba/bus.h>
#include <linux/bug.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/spinlock_types.h>
#include <mach/spear.h>
#include <mach/misc_regs.h>
static spinlock_t lock = __SPIN_LOCK_UNLOCKED(x);
struct {
unsigned char busy;
unsigned char val;
} signals[16] = {{0, 0}, };
int pl080_get_signal(struct pl08x_dma_chan *ch)
{
const struct pl08x_channel_data *cd = ch->cd;
unsigned int signal = cd->min_signal, val;
unsigned long flags;
spin_lock_irqsave(&lock, flags);
/* Return if signal is already acquired by somebody else */
if (signals[signal].busy &&
(signals[signal].val != cd->muxval)) {
spin_unlock_irqrestore(&lock, flags);
return -EBUSY;
}
/* If acquiring for the first time, configure it */
if (!signals[signal].busy) {
val = readl(DMA_CHN_CFG);
/*
* Each request line has two bits in DMA_CHN_CFG register. To
* goto the bits of current request line, do left shift of
* value by 2 * signal number.
*/
val &= ~(0x3 << (signal * 2));
val |= cd->muxval << (signal * 2);
writel(val, DMA_CHN_CFG);
}
signals[signal].busy++;
signals[signal].val = cd->muxval;
spin_unlock_irqrestore(&lock, flags);
return signal;
}
void pl080_put_signal(struct pl08x_dma_chan *ch)
{
const struct pl08x_channel_data *cd = ch->cd;
unsigned long flags;
spin_lock_irqsave(&lock, flags);
/* if signal is not used */
if (!signals[cd->min_signal].busy)
BUG();
signals[cd->min_signal].busy--;
spin_unlock_irqrestore(&lock, flags);
}