/* * arch/arm/plat-spear/pl080.c * * DMAC pl080 definitions for SPEAr platform * * Copyright (C) 2012 ST Microelectronics * Viresh Kumar <vireshk@kernel.org> * * 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(const struct pl08x_channel_data *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(const struct pl08x_channel_data *cd, int signal) { unsigned long flags; spin_lock_irqsave(&lock, flags); /* if signal is not used */ if (!signals[signal].busy) BUG(); signals[signal].busy--; spin_unlock_irqrestore(&lock, flags); }