diff options
Diffstat (limited to 'arch/arm/kernel/dma.c')
| -rw-r--r-- | arch/arm/kernel/dma.c | 251 |
1 files changed, 251 insertions, 0 deletions
diff --git a/arch/arm/kernel/dma.c b/arch/arm/kernel/dma.c new file mode 100644 index 0000000..d006085 --- /dev/null +++ b/arch/arm/kernel/dma.c @@ -0,0 +1,251 @@ +/* + * linux/arch/arm/kernel/dma.c + * + * Copyright (C) 1995-2000 Russell King + * + * 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. + * + * Front-end to the DMA handling. This handles the allocation/freeing + * of DMA channels, and provides a unified interface to the machines + * DMA facilities. + */ +#include <linux/module.h> +#include <linux/init.h> +#include <linux/spinlock.h> +#include <linux/errno.h> + +#include <asm/dma.h> + +#include <asm/mach/dma.h> + +DEFINE_SPINLOCK(dma_spin_lock); +EXPORT_SYMBOL(dma_spin_lock); + +static dma_t dma_chan[MAX_DMA_CHANNELS]; + +/* + * Request DMA channel + * + * On certain platforms, we have to allocate an interrupt as well... + */ +int request_dma(dmach_t channel, const char *device_id) +{ + dma_t *dma = dma_chan + channel; + int ret; + + if (channel >= MAX_DMA_CHANNELS || !dma->d_ops) + goto bad_dma; + + if (xchg(&dma->lock, 1) != 0) + goto busy; + + dma->device_id = device_id; + dma->active = 0; + dma->invalid = 1; + + ret = 0; + if (dma->d_ops->request) + ret = dma->d_ops->request(channel, dma); + + if (ret) + xchg(&dma->lock, 0); + + return ret; + +bad_dma: + printk(KERN_ERR "dma: trying to allocate DMA%d\n", channel); + return -EINVAL; + +busy: + return -EBUSY; +} +EXPORT_SYMBOL(request_dma); + +/* + * Free DMA channel + * + * On certain platforms, we have to free interrupt as well... + */ +void free_dma(dmach_t channel) +{ + dma_t *dma = dma_chan + channel; + + if (channel >= MAX_DMA_CHANNELS || !dma->d_ops) + goto bad_dma; + + if (dma->active) { + printk(KERN_ERR "dma%d: freeing active DMA\n", channel); + dma->d_ops->disable(channel, dma); + dma->active = 0; + } + + if (xchg(&dma->lock, 0) != 0) { + if (dma->d_ops->free) + dma->d_ops->free(channel, dma); + return; + } + + printk(KERN_ERR "dma%d: trying to free free DMA\n", channel); + return; + +bad_dma: + printk(KERN_ERR "dma: trying to free DMA%d\n", channel); +} +EXPORT_SYMBOL(free_dma); + +/* Set DMA Scatter-Gather list + */ +void set_dma_sg (dmach_t channel, struct scatterlist *sg, int nr_sg) +{ + dma_t *dma = dma_chan + channel; + + if (dma->active) + printk(KERN_ERR "dma%d: altering DMA SG while " + "DMA active\n", channel); + + dma->sg = sg; + dma->sgcount = nr_sg; + dma->invalid = 1; +} +EXPORT_SYMBOL(set_dma_sg); + +/* Set DMA address + * + * Copy address to the structure, and set the invalid bit + */ +void __set_dma_addr (dmach_t channel, void *addr) +{ + dma_t *dma = dma_chan + channel; + + if (dma->active) + printk(KERN_ERR "dma%d: altering DMA address while " + "DMA active\n", channel); + + dma->sg = NULL; + dma->addr = addr; + dma->invalid = 1; +} +EXPORT_SYMBOL(__set_dma_addr); + +/* Set DMA byte count + * + * Copy address to the structure, and set the invalid bit + */ +void set_dma_count (dmach_t channel, unsigned long count) +{ + dma_t *dma = dma_chan + channel; + + if (dma->active) + printk(KERN_ERR "dma%d: altering DMA count while " + "DMA active\n", channel); + + dma->sg = NULL; + dma->count = count; + dma->invalid = 1; +} +EXPORT_SYMBOL(set_dma_count); + +/* Set DMA direction mode + */ +void set_dma_mode (dmach_t channel, dmamode_t mode) +{ + dma_t *dma = dma_chan + channel; + + if (dma->active) + printk(KERN_ERR "dma%d: altering DMA mode while " + "DMA active\n", channel); + + dma->dma_mode = mode; + dma->invalid = 1; +} +EXPORT_SYMBOL(set_dma_mode); + +/* Enable DMA channel + */ +void enable_dma (dmach_t channel) +{ + dma_t *dma = dma_chan + channel; + + if (!dma->lock) + goto free_dma; + + if (dma->active == 0) { + dma->active = 1; + dma->d_ops->enable(channel, dma); + } + return; + +free_dma: + printk(KERN_ERR "dma%d: trying to enable free DMA\n", channel); + BUG(); +} +EXPORT_SYMBOL(enable_dma); + +/* Disable DMA channel + */ +void disable_dma (dmach_t channel) +{ + dma_t *dma = dma_chan + channel; + + if (!dma->lock) + goto free_dma; + + if (dma->active == 1) { + dma->active = 0; + dma->d_ops->disable(channel, dma); + } + return; + +free_dma: + printk(KERN_ERR "dma%d: trying to disable free DMA\n", channel); + BUG(); +} +EXPORT_SYMBOL(disable_dma); + +/* + * Is the specified DMA channel active? + */ +int dma_channel_active(dmach_t channel) +{ + return dma_chan[channel].active; +} +EXPORT_SYMBOL(dma_channel_active); + +void set_dma_page(dmach_t channel, char pagenr) +{ + printk(KERN_ERR "dma%d: trying to set_dma_page\n", channel); +} +EXPORT_SYMBOL(set_dma_page); + +void set_dma_speed(dmach_t channel, int cycle_ns) +{ + dma_t *dma = dma_chan + channel; + int ret = 0; + + if (dma->d_ops->setspeed) + ret = dma->d_ops->setspeed(channel, dma, cycle_ns); + dma->speed = ret; +} +EXPORT_SYMBOL(set_dma_speed); + +int get_dma_residue(dmach_t channel) +{ + dma_t *dma = dma_chan + channel; + int ret = 0; + + if (dma->d_ops->residue) + ret = dma->d_ops->residue(channel, dma); + + return ret; +} +EXPORT_SYMBOL(get_dma_residue); + +static int __init init_dma(void) +{ + arch_dma_init(dma_chan); + return 0; +} + +core_initcall(init_dma); |
