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
  20 static spinlock_t lock = __SPIN_LOCK_UNLOCKED(x);
  21
  22 struct {
  23         unsigned char busy;
  24         unsigned char val;
  25 } signals[16] = {{0, 0}, };
  26
  27 int pl080_get_signal(const struct pl08x_channel_data *cd)
  28 {
  29         unsigned int signal = cd->min_signal, val;
  30         unsigned long flags;
  31
  32         spin_lock_irqsave(&lock, flags);
  33
  34         /* Return if signal is already acquired by somebody else */
  35         if (signals[signal].busy &&
  36                         (signals[signal].val != cd->muxval)) {
  37                 spin_unlock_irqrestore(&lock, flags);
  38                 return -EBUSY;
  39         }
  40
  41         /* If acquiring for the first time, configure it */
  42         if (!signals[signal].busy) {
  43                 val = readl(DMA_CHN_CFG);
  44
  45                 /*
  46                  * Each request line has two bits in DMA_CHN_CFG register. To
  47                  * goto the bits of current request line, do left shift of
  48                  * value by 2 * signal number.
  49                  */
  50                 val &= ~(0x3 << (signal * 2));
  51                 val |= cd->muxval << (signal * 2);
  52                 writel(val, DMA_CHN_CFG);
  53         }
  54
  55         signals[signal].busy++;
  56         signals[signal].val = cd->muxval;
  57         spin_unlock_irqrestore(&lock, flags);
  58
  59         return signal;
  60 }
  61
  62 void pl080_put_signal(const struct pl08x_channel_data *cd, int signal)
  63 {
  64         unsigned long flags;
  65
  66         spin_lock_irqsave(&lock, flags);
  67
  68         /* if signal is not used */
  69         if (!signals[signal].busy)
  70                 BUG();
  71
  72         signals[signal].busy--;
  73
  74         spin_unlock_irqrestore(&lock, flags);
  75 }