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 "spear.h" 21 #include "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 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 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