diff options
Diffstat (limited to 'arch/unicore32/kernel/dma.c')
| -rw-r--r-- | arch/unicore32/kernel/dma.c | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/arch/unicore32/kernel/dma.c b/arch/unicore32/kernel/dma.c new file mode 100644 index 00000000000..ae441bc3122 --- /dev/null +++ b/arch/unicore32/kernel/dma.c @@ -0,0 +1,183 @@ +/* + * linux/arch/unicore32/kernel/dma.c + * + * Code specific to PKUnity SoC and UniCore ISA + * + * Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn> + * Copyright (C) 2001-2010 Guan Xuetao + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/module.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/interrupt.h> +#include <linux/errno.h> +#include <linux/io.h> + +#include <asm/system.h> +#include <asm/irq.h> +#include <mach/hardware.h> +#include <mach/dma.h> + +struct dma_channel { + char *name; + puv3_dma_prio prio; + void (*irq_handler)(int, void *); + void (*err_handler)(int, void *); + void *data; +}; + +static struct dma_channel dma_channels[MAX_DMA_CHANNELS]; + +int puv3_request_dma(char *name, puv3_dma_prio prio, + void (*irq_handler)(int, void *), + void (*err_handler)(int, void *), + void *data) +{ + unsigned long flags; + int i, found = 0; + + /* basic sanity checks */ + if (!name) + return -EINVAL; + + local_irq_save(flags); + + do { + /* try grabbing a DMA channel with the requested priority */ + for (i = 0; i < MAX_DMA_CHANNELS; i++) { + if ((dma_channels[i].prio == prio) && + !dma_channels[i].name) { + found = 1; + break; + } + } + /* if requested prio group is full, try a hier priority */ + } while (!found && prio--); + + if (found) { + dma_channels[i].name = name; + dma_channels[i].irq_handler = irq_handler; + dma_channels[i].err_handler = err_handler; + dma_channels[i].data = data; + } else { + printk(KERN_WARNING "No more available DMA channels for %s\n", + name); + i = -ENODEV; + } + + local_irq_restore(flags); + return i; +} +EXPORT_SYMBOL(puv3_request_dma); + +void puv3_free_dma(int dma_ch) +{ + unsigned long flags; + + if (!dma_channels[dma_ch].name) { + printk(KERN_CRIT + "%s: trying to free channel %d which is already freed\n", + __func__, dma_ch); + return; + } + + local_irq_save(flags); + dma_channels[dma_ch].name = NULL; + dma_channels[dma_ch].err_handler = NULL; + local_irq_restore(flags); +} +EXPORT_SYMBOL(puv3_free_dma); + +static irqreturn_t dma_irq_handler(int irq, void *dev_id) +{ + int i, dint; + + dint = readl(DMAC_ITCSR); + for (i = 0; i < MAX_DMA_CHANNELS; i++) { + if (dint & DMAC_CHANNEL(i)) { + struct dma_channel *channel = &dma_channels[i]; + + /* Clear TC interrupt of channel i */ + writel(DMAC_CHANNEL(i), DMAC_ITCCR); + writel(0, DMAC_ITCCR); + + if (channel->name && channel->irq_handler) { + channel->irq_handler(i, channel->data); + } else { + /* + * IRQ for an unregistered DMA channel: + * let's clear the interrupts and disable it. + */ + printk(KERN_WARNING "spurious IRQ for" + " DMA channel %d\n", i); + } + } + } + return IRQ_HANDLED; +} + +static irqreturn_t dma_err_handler(int irq, void *dev_id) +{ + int i, dint; + + dint = readl(DMAC_IESR); + for (i = 0; i < MAX_DMA_CHANNELS; i++) { + if (dint & DMAC_CHANNEL(i)) { + struct dma_channel *channel = &dma_channels[i]; + + /* Clear Err interrupt of channel i */ + writel(DMAC_CHANNEL(i), DMAC_IECR); + writel(0, DMAC_IECR); + + if (channel->name && channel->err_handler) { + channel->err_handler(i, channel->data); + } else { + /* + * IRQ for an unregistered DMA channel: + * let's clear the interrupts and disable it. + */ + printk(KERN_WARNING "spurious IRQ for" + " DMA channel %d\n", i); + } + } + } + return IRQ_HANDLED; +} + +int __init puv3_init_dma(void) +{ + int i, ret; + + /* dma channel priorities on v8 processors: + * ch 0 - 1 <--> (0) DMA_PRIO_HIGH + * ch 2 - 3 <--> (1) DMA_PRIO_MEDIUM + * ch 4 - 5 <--> (2) DMA_PRIO_LOW + */ + for (i = 0; i < MAX_DMA_CHANNELS; i++) { + puv3_stop_dma(i); + dma_channels[i].name = NULL; + dma_channels[i].prio = min((i & 0x7) >> 1, DMA_PRIO_LOW); + } + + ret = request_irq(IRQ_DMA, dma_irq_handler, 0, "DMA", NULL); + if (ret) { + printk(KERN_CRIT "Can't register IRQ for DMA\n"); + return ret; + } + + ret = request_irq(IRQ_DMAERR, dma_err_handler, 0, "DMAERR", NULL); + if (ret) { + printk(KERN_CRIT "Can't register IRQ for DMAERR\n"); + free_irq(IRQ_DMA, "DMA"); + return ret; + } + + return 0; +} + +postcore_initcall(puv3_init_dma); |