arch/arm/plat-spear/pl080.c

   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 <viresh.linux@gmail.com>
   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
  30 int pl080_get_signal(struct pl08x_dma_chan *ch)
  31 {
  32         const struct pl08x_channel_data *cd = ch->cd;
  33         unsigned int signal = cd->min_signal, val;
  34         unsigned long flags;
  35
  36         spin_lock_irqsave(&lock, flags);
  37
  38         /* Return if signal is already acquired by somebody else */
  39         if (signals[signal].busy &&
  40                         (signals[signal].val != cd->muxval)) {
  41                 spin_unlock_irqrestore(&lock, flags);
  42                 return -EBUSY;
  43         }
  44
  45         /* If acquiring for the first time, configure it */
  46         if (!signals[signal].busy) {
  47                 val = readl(DMA_CHN_CFG);
  48
  49                 /*
  50                  * Each request line has two bits in DMA_CHN_CFG register. To
  51                  * goto the bits of current request line, do left shift of
  52                  * value by 2 * signal number.
  53                  */
  54                 val &= ~(0x3 << (signal * 2));
  55                 val |= cd->muxval << (signal * 2);
  56                 writel(val, DMA_CHN_CFG);
  57         }
  58
  59         signals[signal].busy++;
  60         signals[signal].val = cd->muxval;
  61         spin_unlock_irqrestore(&lock, flags);
  62
  63         return signal;
  64 }
  65
  66 void pl080_put_signal(struct pl08x_dma_chan *ch)
  67 {
  68         const struct pl08x_channel_data *cd = ch->cd;
  69         unsigned long flags;
  70
  71         spin_lock_irqsave(&lock, flags);
  72
  73         /* if signal is not used */
  74         if (!signals[cd->min_signal].busy)
  75                 BUG();
  76
  77         signals[cd->min_signal].busy--;
  78
  79         spin_unlock_irqrestore(&lock, flags);
  80 }