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 0000000..96e3036
--- /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, &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);
+