LXR linux/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
  25struct 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
  33static struct dma_channel dma_channels[MAX_DMA_CHANNELS];
  34
  35int 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}
  75EXPORT_SYMBOL(puv3_request_dma);
  76
  77void 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}
  93EXPORT_SYMBOL(puv3_free_dma);
  94
  95static 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
 123static 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
 151int __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
 182postcore_initcall(puv3_init_dma);
 183