arch/sh/drivers/dma/dma-api.c - maze/linux - Git at Google

 /*
  * 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, &registered_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(&registered_dmac_list))
 		return 0;

 	/*
 	 * Iterate over each registered DMAC
 	 */
 	list_for_each_safe(pos, tmp, &registered_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, &registered_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);
	/*
	* 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, &registered_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(&registered_dmac_list))
	return 0;

	/*
	* Iterate over each registered DMAC
	*/
	list_for_each_safe(pos, tmp, &registered_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, &registered_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);