arch/arm/mach-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 <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 <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(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 }