arch/unicore32/kernel/dma.c

   1 /*
   2  * linux/arch/unicore32/kernel/dma.c
   3  *
   4  * Code specific to PKUnity SoC and UniCore ISA
   5  *
   6  *      Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
   7  *      Copyright (C) 2001-2010 Guan Xuetao
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 #include <linux/module.h>
  15 #include <linux/init.h>
  16 #include <linux/kernel.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/errno.h>
  19 #include <linux/io.h>
  20
  21 #include <asm/irq.h>
  22 #include <mach/hardware.h>
  23 #include <mach/dma.h>
  24
  25 struct dma_channel {
  26         char *name;
  27         puv3_dma_prio prio;
  28         void (*irq_handler)(int, void *);
  29         void (*err_handler)(int, void *);
  30         void *data;
  31 };
  32
  33 static struct dma_channel dma_channels[MAX_DMA_CHANNELS];
  34
  35 int puv3_request_dma(char *name, puv3_dma_prio prio,
  36                          void (*irq_handler)(int, void *),
  37                          void (*err_handler)(int, void *),
  38                          void *data)
  39 {
  40         unsigned long flags;
  41         int i, found = 0;
  42
  43         /* basic sanity checks */
  44         if (!name)
  45                 return -EINVAL;
  46
  47         local_irq_save(flags);
  48
  49         do {
  50                 /* try grabbing a DMA channel with the requested priority */
  51                 for (i = 0; i < MAX_DMA_CHANNELS; i++) {
  52                         if ((dma_channels[i].prio == prio) &&
  53                             !dma_channels[i].name) {
  54                                 found = 1;
  55                                 break;
  56                         }
  57                 }
  58                 /* if requested prio group is full, try a hier priority */
  59         } while (!found && prio--);
  60
  61         if (found) {
  62                 dma_channels[i].name = name;
  63                 dma_channels[i].irq_handler = irq_handler;
  64                 dma_channels[i].err_handler = err_handler;
  65                 dma_channels[i].data = data;
  66         } else {
  67                 printk(KERN_WARNING "No more available DMA channels for %s\n",
  68                                 name);
  69                 i = -ENODEV;
  70         }
  71
  72         local_irq_restore(flags);
  73         return i;
  74 }
  75 EXPORT_SYMBOL(puv3_request_dma);
  76
  77 void puv3_free_dma(int dma_ch)
  78 {
  79         unsigned long flags;
  80
  81         if (!dma_channels[dma_ch].name) {
  82                 printk(KERN_CRIT
  83                         "%s: trying to free channel %d which is already freed\n",
  84                         __func__, dma_ch);
  85                 return;
  86         }
  87
  88         local_irq_save(flags);
  89         dma_channels[dma_ch].name = NULL;
  90         dma_channels[dma_ch].err_handler = NULL;
  91         local_irq_restore(flags);
  92 }
  93 EXPORT_SYMBOL(puv3_free_dma);
  94
  95 static irqreturn_t dma_irq_handler(int irq, void *dev_id)
  96 {
  97         int i, dint;
  98
  99         dint = readl(DMAC_ITCSR);
 100         for (i = 0; i < MAX_DMA_CHANNELS; i++) {
 101                 if (dint & DMAC_CHANNEL(i)) {
 102                         struct dma_channel *channel = &dma_channels[i];
 103
 104                         /* Clear TC interrupt of channel i */
 105                         writel(DMAC_CHANNEL(i), DMAC_ITCCR);
 106                         writel(0, DMAC_ITCCR);
 107
 108                         if (channel->name && channel->irq_handler) {
 109                                 channel->irq_handler(i, channel->data);
 110                         } else {
 111                                 /*
 112                                  * IRQ for an unregistered DMA channel:
 113                                  * let's clear the interrupts and disable it.
 114                                  */
 115                                 printk(KERN_WARNING "spurious IRQ for"
 116                                                 " DMA channel %d\n", i);
 117                         }
 118                 }
 119         }
 120         return IRQ_HANDLED;
 121 }
 122
 123 static irqreturn_t dma_err_handler(int irq, void *dev_id)
 124 {
 125         int i, dint;
 126
 127         dint = readl(DMAC_IESR);
 128         for (i = 0; i < MAX_DMA_CHANNELS; i++) {
 129                 if (dint & DMAC_CHANNEL(i)) {
 130                         struct dma_channel *channel = &dma_channels[i];
 131
 132                         /* Clear Err interrupt of channel i */
 133                         writel(DMAC_CHANNEL(i), DMAC_IECR);
 134                         writel(0, DMAC_IECR);
 135
 136                         if (channel->name && channel->err_handler) {
 137                                 channel->err_handler(i, channel->data);
 138                         } else {
 139                                 /*
 140                                  * IRQ for an unregistered DMA channel:
 141                                  * let's clear the interrupts and disable it.
 142                                  */
 143                                 printk(KERN_WARNING "spurious IRQ for"
 144                                                 " DMA channel %d\n", i);
 145                         }
 146                 }
 147         }
 148         return IRQ_HANDLED;
 149 }
 150
 151 int __init puv3_init_dma(void)
 152 {
 153         int i, ret;
 154
 155         /* dma channel priorities on v8 processors:
 156          * ch 0 - 1  <--> (0) DMA_PRIO_HIGH
 157          * ch 2 - 3  <--> (1) DMA_PRIO_MEDIUM
 158          * ch 4 - 5  <--> (2) DMA_PRIO_LOW
 159          */
 160         for (i = 0; i < MAX_DMA_CHANNELS; i++) {
 161                 puv3_stop_dma(i);
 162                 dma_channels[i].name = NULL;
 163                 dma_channels[i].prio = min((i & 0x7) >> 1, DMA_PRIO_LOW);
 164         }
 165
 166         ret = request_irq(IRQ_DMA, dma_irq_handler, 0, "DMA", NULL);
 167         if (ret) {
 168                 printk(KERN_CRIT "Can't register IRQ for DMA\n");
 169                 return ret;
 170         }
 171
 172         ret = request_irq(IRQ_DMAERR, dma_err_handler, 0, "DMAERR", NULL);
 173         if (ret) {
 174                 printk(KERN_CRIT "Can't register IRQ for DMAERR\n");
 175                 free_irq(IRQ_DMA, "DMA");
 176                 return ret;
 177         }
 178
 179         return 0;
 180 }
 181
 182 postcore_initcall(puv3_init_dma);