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Diffstat (limited to 'arch/sh/drivers/dma/dma-api.c')
| -rw-r--r-- | arch/sh/drivers/dma/dma-api.c | 292 |
1 files changed, 292 insertions, 0 deletions
diff --git a/arch/sh/drivers/dma/dma-api.c b/arch/sh/drivers/dma/dma-api.c new file mode 100644 index 000000000000..96e3036ec2bb --- /dev/null +++ b/arch/sh/drivers/dma/dma-api.c @@ -0,0 +1,292 @@ +/* + * arch/sh/drivers/dma/dma-api.c + * + * SuperH-specific DMA management API + * + * Copyright (C) 2003, 2004 Paul Mundt + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + */ +#include <linux/init.h> +#include <linux/module.h> +#include <linux/interrupt.h> +#include <linux/spinlock.h> +#include <linux/proc_fs.h> +#include <linux/list.h> +#include <asm/dma.h> + +DEFINE_SPINLOCK(dma_spin_lock); +static LIST_HEAD(registered_dmac_list); + +/* + * A brief note about the reasons for this API as it stands. + * + * For starters, the old ISA DMA API didn't work for us for a number of + * reasons, for one, the vast majority of channels on the SH DMAC are + * dual-address mode only, and both the new and the old DMA APIs are after the + * concept of managing a DMA buffer, which doesn't overly fit this model very + * well. In addition to which, the new API is largely geared at IOMMUs and + * GARTs, and doesn't even support the channel notion very well. + * + * The other thing that's a marginal issue, is the sheer number of random DMA + * engines that are present (ie, in boards like the Dreamcast), some of which + * cascade off of the SH DMAC, and others do not. As such, there was a real + * need for a scalable subsystem that could deal with both single and + * dual-address mode usage, in addition to interoperating with cascaded DMACs. + * + * There really isn't any reason why this needs to be SH specific, though I'm + * not aware of too many other processors (with the exception of some MIPS) + * that have the same concept of a dual address mode, or any real desire to + * actually make use of the DMAC even if such a subsystem were exposed + * elsewhere. + * + * The idea for this was derived from the ARM port, which acted as an excellent + * reference when trying to address these issues. + * + * It should also be noted that the decision to add Yet Another DMA API(tm) to + * the kernel wasn't made easily, and was only decided upon after conferring + * with jejb with regards to the state of the old and new APIs as they applied + * to these circumstances. Philip Blundell was also a great help in figuring + * out some single-address mode DMA semantics that were otherwise rather + * confusing. + */ + +struct dma_info *get_dma_info(unsigned int chan) +{ + struct list_head *pos, *tmp; + unsigned int total = 0; + + /* + * Look for each DMAC's range to determine who the owner of + * the channel is. + */ + list_for_each_safe(pos, tmp, ®istered_dmac_list) { + struct dma_info *info = list_entry(pos, struct dma_info, list); + + total += info->nr_channels; + if (chan > total) + continue; + + return info; + } + + return NULL; +} + +struct dma_channel *get_dma_channel(unsigned int chan) +{ + struct dma_info *info = get_dma_info(chan); + + if (!info) + return ERR_PTR(-EINVAL); + + return info->channels + chan; +} + +int get_dma_residue(unsigned int chan) +{ + struct dma_info *info = get_dma_info(chan); + struct dma_channel *channel = &info->channels[chan]; + + if (info->ops->get_residue) + return info->ops->get_residue(channel); + + return 0; +} + +int request_dma(unsigned int chan, const char *dev_id) +{ + struct dma_info *info = get_dma_info(chan); + struct dma_channel *channel = &info->channels[chan]; + + down(&channel->sem); + + if (!info->ops || chan >= MAX_DMA_CHANNELS) { + up(&channel->sem); + return -EINVAL; + } + + atomic_set(&channel->busy, 1); + + strlcpy(channel->dev_id, dev_id, sizeof(channel->dev_id)); + + up(&channel->sem); + + if (info->ops->request) + return info->ops->request(channel); + + return 0; +} + +void free_dma(unsigned int chan) +{ + struct dma_info *info = get_dma_info(chan); + struct dma_channel *channel = &info->channels[chan]; + + if (info->ops->free) + info->ops->free(channel); + + atomic_set(&channel->busy, 0); +} + +void dma_wait_for_completion(unsigned int chan) +{ + struct dma_info *info = get_dma_info(chan); + struct dma_channel *channel = &info->channels[chan]; + + if (channel->flags & DMA_TEI_CAPABLE) { + wait_event(channel->wait_queue, + (info->ops->get_residue(channel) == 0)); + return; + } + + while (info->ops->get_residue(channel)) + cpu_relax(); +} + +void dma_configure_channel(unsigned int chan, unsigned long flags) +{ + struct dma_info *info = get_dma_info(chan); + struct dma_channel *channel = &info->channels[chan]; + + if (info->ops->configure) + info->ops->configure(channel, flags); +} + +int dma_xfer(unsigned int chan, unsigned long from, + unsigned long to, size_t size, unsigned int mode) +{ + struct dma_info *info = get_dma_info(chan); + struct dma_channel *channel = &info->channels[chan]; + + channel->sar = from; + channel->dar = to; + channel->count = size; + channel->mode = mode; + + return info->ops->xfer(channel); +} + +#ifdef CONFIG_PROC_FS +static int dma_read_proc(char *buf, char **start, off_t off, + int len, int *eof, void *data) +{ + struct list_head *pos, *tmp; + char *p = buf; + + if (list_empty(®istered_dmac_list)) + return 0; + + /* + * Iterate over each registered DMAC + */ + list_for_each_safe(pos, tmp, ®istered_dmac_list) { + struct dma_info *info = list_entry(pos, struct dma_info, list); + int i; + + /* + * Iterate over each channel + */ + for (i = 0; i < info->nr_channels; i++) { + struct dma_channel *channel = info->channels + i; + + if (!(channel->flags & DMA_CONFIGURED)) + continue; + + p += sprintf(p, "%2d: %14s %s\n", i, + info->name, channel->dev_id); + } + } + + return p - buf; +} +#endif + + +int __init register_dmac(struct dma_info *info) +{ + int i; + + INIT_LIST_HEAD(&info->list); + + printk(KERN_INFO "DMA: Registering %s handler (%d channel%s).\n", + info->name, info->nr_channels, + info->nr_channels > 1 ? "s" : ""); + + BUG_ON((info->flags & DMAC_CHANNELS_CONFIGURED) && !info->channels); + + /* + * Don't touch pre-configured channels + */ + if (!(info->flags & DMAC_CHANNELS_CONFIGURED)) { + unsigned int size; + + size = sizeof(struct dma_channel) * info->nr_channels; + + info->channels = kmalloc(size, GFP_KERNEL); + if (!info->channels) + return -ENOMEM; + + memset(info->channels, 0, size); + } + + for (i = 0; i < info->nr_channels; i++) { + struct dma_channel *chan = info->channels + i; + + chan->chan = i; + + memcpy(chan->dev_id, "Unused", 7); + + if (info->flags & DMAC_CHANNELS_TEI_CAPABLE) + chan->flags |= DMA_TEI_CAPABLE; + + init_MUTEX(&chan->sem); + init_waitqueue_head(&chan->wait_queue); + +#ifdef CONFIG_SYSFS + dma_create_sysfs_files(chan); +#endif + } + + list_add(&info->list, ®istered_dmac_list); + + return 0; +} + +void __exit unregister_dmac(struct dma_info *info) +{ + if (!(info->flags & DMAC_CHANNELS_CONFIGURED)) + kfree(info->channels); + + list_del(&info->list); +} + +static int __init dma_api_init(void) +{ + printk("DMA: Registering DMA API.\n"); + +#ifdef CONFIG_PROC_FS + create_proc_read_entry("dma", 0, 0, dma_read_proc, 0); +#endif + + return 0; +} + +subsys_initcall(dma_api_init); + +MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>"); +MODULE_DESCRIPTION("DMA API for SuperH"); +MODULE_LICENSE("GPL"); + +EXPORT_SYMBOL(request_dma); +EXPORT_SYMBOL(free_dma); +EXPORT_SYMBOL(register_dmac); +EXPORT_SYMBOL(get_dma_residue); +EXPORT_SYMBOL(get_dma_info); +EXPORT_SYMBOL(get_dma_channel); +EXPORT_SYMBOL(dma_xfer); +EXPORT_SYMBOL(dma_wait_for_completion); +EXPORT_SYMBOL(dma_configure_channel); + |