arch/arm/mach-spear/pl080.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * arch/arm/plat-spear/pl080.c
   4  *
   5  * DMAC pl080 definitions for SPEAr platform
   6  *
   7  * Copyright (C) 2012 ST Microelectronics
   8  * Viresh Kumar <vireshk@kernel.org>
   9  */
  10
  11 #include <linux/amba/pl08x.h>
  12 #include <linux/amba/bus.h>
  13 #include <linux/bug.h>
  14 #include <linux/err.h>
  15 #include <linux/io.h>
  16 #include <linux/spinlock_types.h>
  17 #include "spear.h"
  18 #include "misc_regs.h"
  19 #include "pl080.h"
  20
  21 static spinlock_t lock = __SPIN_LOCK_UNLOCKED(x);
  22
  23 struct {
  24         unsigned char busy;
  25         unsigned char val;
  26 } signals[16] = {{0, 0}, };
  27
  28 int pl080_get_signal(const struct pl08x_channel_data *cd)
  29 {
  30         unsigned int signal = cd->min_signal, val;
  31         unsigned long flags;
  32
  33         spin_lock_irqsave(&lock, flags);
  34
  35         /* Return if signal is already acquired by somebody else */
  36         if (signals[signal].busy &&
  37                         (signals[signal].val != cd->muxval)) {
  38                 spin_unlock_irqrestore(&lock, flags);
  39                 return -EBUSY;
  40         }
  41
  42         /* If acquiring for the first time, configure it */
  43         if (!signals[signal].busy) {
  44                 val = readl(DMA_CHN_CFG);
  45
  46                 /*
  47                  * Each request line has two bits in DMA_CHN_CFG register. To
  48                  * goto the bits of current request line, do left shift of
  49                  * value by 2 * signal number.
  50                  */
  51                 val &= ~(0x3 << (signal * 2));
  52                 val |= cd->muxval << (signal * 2);
  53                 writel(val, DMA_CHN_CFG);
  54         }
  55
  56         signals[signal].busy++;
  57         signals[signal].val = cd->muxval;
  58         spin_unlock_irqrestore(&lock, flags);
  59
  60         return signal;
  61 }
  62
  63 void pl080_put_signal(const struct pl08x_channel_data *cd, int signal)
  64 {
  65         unsigned long flags;
  66
  67         spin_lock_irqsave(&lock, flags);
  68
  69         /* if signal is not used */
  70         if (!signals[signal].busy)
  71                 BUG();
  72
  73         signals[signal].busy--;
  74
  75         spin_unlock_irqrestore(&lock, flags);
  76 }