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