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