sh: dma-api channel capability extensions.

This extends the SH DMA API for allowing handling of DMA
channels based off of their respective capabilities.

A couple of functions are added to the existing API,
the core bits are register_chan_caps() for registering
channel capabilities, and request_dma_bycap() for fetching
a channel dynamically based off of a capability set.
Signed-off-by: Mark Glaisher <mark.glaisher@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/drivers/dma/dma-api.c

@@ -11,61 +11,27 @@
  */
 #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 <linux/platform_device.h>
+#include <linux/mm.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 dma_info *info;
-	unsigned int total = 0;
 
 	/*
 	 * Look for each DMAC's range to determine who the owner of
 	 * the channel is.
 	 */
 	list_for_each_entry(info, &registered_dmac_list, list) {
-		total += info->nr_channels;
-		if (chan > total)
+		if ((chan <  info->first_channel_nr) ||
+		    (chan >= info->first_channel_nr + info->nr_channels))
 			continue;
 
 		return info;
@@ -73,6 +39,22 @@ struct dma_info *get_dma_info(unsigned int chan)
 
 	return NULL;
 }
+EXPORT_SYMBOL(get_dma_info);
+
+struct dma_info *get_dma_info_by_name(const char *dmac_name)
+{
+	struct dma_info *info;
+
+	list_for_each_entry(info, &registered_dmac_list, list) {
+		if (dmac_name && (strcmp(dmac_name, info->name) != 0))
+			continue;
+		else
+			return info;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL(get_dma_info_by_name);
 
 static unsigned int get_nr_channels(void)
 {
@@ -91,63 +73,161 @@ static unsigned int get_nr_channels(void)
 struct dma_channel *get_dma_channel(unsigned int chan)
 {
 	struct dma_info *info = get_dma_info(chan);
+	struct dma_channel *channel;
+	int i;
 
-	if (!info)
+	if (unlikely(!info))
 		return ERR_PTR(-EINVAL);
 
-	return info->channels + chan;
+	for (i = 0; i < info->nr_channels; i++) {
+		channel = &info->channels[i];
+		if (channel->chan == chan)
+			return channel;
+	}
+
+	return NULL;
 }
+EXPORT_SYMBOL(get_dma_channel);
 
 int get_dma_residue(unsigned int chan)
 {
 	struct dma_info *info = get_dma_info(chan);
-	struct dma_channel *channel = &info->channels[chan];
+	struct dma_channel *channel = get_dma_channel(chan);
 
 	if (info->ops->get_residue)
 		return info->ops->get_residue(channel);
 
 	return 0;
 }
+EXPORT_SYMBOL(get_dma_residue);
 
-int request_dma(unsigned int chan, const char *dev_id)
+static int search_cap(const char **haystack, const char *needle)
 {
-	struct dma_info *info = get_dma_info(chan);
-	struct dma_channel *channel = &info->channels[chan];
+	const char **p;
+
+	for (p = haystack; *p; p++)
+		if (strcmp(*p, needle) == 0)
+			return 1;
+
+	return 0;
+}
+
+/**
+ * request_dma_bycap - Allocate a DMA channel based on its capabilities
+ * @dmac: List of DMA controllers to search
+ * @caps: List of capabilites
+ *
+ * Search all channels of all DMA controllers to find a channel which
+ * matches the requested capabilities. The result is the channel
+ * number if a match is found, or %-ENODEV if no match is found.
+ *
+ * Note that not all DMA controllers export capabilities, in which
+ * case they can never be allocated using this API, and so
+ * request_dma() must be used specifying the channel number.
+ */
+int request_dma_bycap(const char **dmac, const char **caps, const char *dev_id)
+{
+	unsigned int found = 0;
+	struct dma_info *info;
+	const char **p;
+	int i;
+
+	BUG_ON(!dmac || !caps);
+
+	list_for_each_entry(info, &registered_dmac_list, list)
+		if (strcmp(*dmac, info->name) == 0) {
+			found = 1;
+			break;
+		}
+
+	if (!found)
+		return -ENODEV;
+
+	for (i = 0; i < info->nr_channels; i++) {
+		struct dma_channel *channel = &info->channels[i];
+
+		if (unlikely(!channel->caps))
+			continue;
+
+		for (p = caps; *p; p++) {
+			if (!search_cap(channel->caps, *p))
+				break;
+			if (request_dma(channel->chan, dev_id) == 0)
+				return channel->chan;
+		}
+	}
+
+	return -EINVAL;
+}
+EXPORT_SYMBOL(request_dma_bycap);
+
+int dmac_search_free_channel(const char *dev_id)
+{
+	struct dma_channel *channel = { 0 };
+	struct dma_info *info = get_dma_info(0);
+	int i;
+
+	for (i = 0; i < info->nr_channels; i++) {
+		channel = &info->channels[i];
+		if (unlikely(!channel))
+			return -ENODEV;
+
+		if (atomic_read(&channel->busy) == 0)
+			break;
+	}
 
-	down(&channel->sem);
+	if (info->ops->request) {
+		int result = info->ops->request(channel);
+		if (result)
+			return result;
 
-	if (!info->ops || chan >= MAX_DMA_CHANNELS) {
-		up(&channel->sem);
-		return -EINVAL;
+		atomic_set(&channel->busy, 1);
+		return channel->chan;
 	}
 
-	atomic_set(&channel->busy, 1);
+	return -ENOSYS;
+}
+
+int request_dma(unsigned int chan, const char *dev_id)
+{
+	struct dma_channel *channel = { 0 };
+	struct dma_info *info = get_dma_info(chan);
+	int result;
+
+	channel = get_dma_channel(chan);
+	if (atomic_xchg(&channel->busy, 1))
+		return -EBUSY;
 
 	strlcpy(channel->dev_id, dev_id, sizeof(channel->dev_id));
 
-	up(&channel->sem);
+	if (info->ops->request) {
+		result = info->ops->request(channel);
+		if (result)
+			atomic_set(&channel->busy, 0);
 
-	if (info->ops->request)
-		return info->ops->request(channel);
+		return result;
+	}
 
 	return 0;
 }
+EXPORT_SYMBOL(request_dma);
 
 void free_dma(unsigned int chan)
 {
 	struct dma_info *info = get_dma_info(chan);
-	struct dma_channel *channel = &info->channels[chan];
+	struct dma_channel *channel = get_dma_channel(chan);
 
 	if (info->ops->free)
 		info->ops->free(channel);
 
 	atomic_set(&channel->busy, 0);
 }
+EXPORT_SYMBOL(free_dma);
 
 void dma_wait_for_completion(unsigned int chan)
 {
 	struct dma_info *info = get_dma_info(chan);
-	struct dma_channel *channel = &info->channels[chan];
+	struct dma_channel *channel = get_dma_channel(chan);
 
 	if (channel->flags & DMA_TEI_CAPABLE) {
 		wait_event(channel->wait_queue,
@@ -158,21 +238,52 @@ void dma_wait_for_completion(unsigned int chan)
 	while (info->ops->get_residue(channel))
 		cpu_relax();
 }
+EXPORT_SYMBOL(dma_wait_for_completion);
+
+int register_chan_caps(const char *dmac, struct dma_chan_caps *caps)
+{
+	struct dma_info *info;
+	unsigned int found = 0;
+	int i;
+
+	list_for_each_entry(info, &registered_dmac_list, list)
+		if (strcmp(dmac, info->name) == 0) {
+			found = 1;
+			break;
+		}
+
+	if (unlikely(!found))
+		return -ENODEV;
+
+	for (i = 0; i < info->nr_channels; i++, caps++) {
+		struct dma_channel *channel;
+
+		if ((info->first_channel_nr + i) != caps->ch_num)
+			return -EINVAL;
+
+		channel = &info->channels[i];
+		channel->caps = caps->caplist;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(register_chan_caps);
 
 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];
+	struct dma_channel *channel = get_dma_channel(chan);
 
 	if (info->ops->configure)
 		info->ops->configure(channel, flags);
 }
+EXPORT_SYMBOL(dma_configure_channel);
 
 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];
+	struct dma_channel *channel = get_dma_channel(chan);
 
 	channel->sar	= from;
 	channel->dar	= to;
@@ -181,8 +292,20 @@ int dma_xfer(unsigned int chan, unsigned long from,
 
 	return info->ops->xfer(channel);
 }
+EXPORT_SYMBOL(dma_xfer);
+
+int dma_extend(unsigned int chan, unsigned long op, void *param)
+{
+	struct dma_info *info = get_dma_info(chan);
+	struct dma_channel *channel = get_dma_channel(chan);
+
+	if (info->ops->extend)
+		return info->ops->extend(channel, op, param);
+
+	return -ENOSYS;
+}
+EXPORT_SYMBOL(dma_extend);
 
-#ifdef CONFIG_PROC_FS
 static int dma_read_proc(char *buf, char **start, off_t off,
 			 int len, int *eof, void *data)
 {
@@ -214,8 +337,6 @@ static int dma_read_proc(char *buf, char **start, off_t off,
 
 	return p - buf;
 }
-#endif
-
 
 int register_dmac(struct dma_info *info)
 {
@@ -224,8 +345,7 @@ int register_dmac(struct dma_info *info)
 	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" : "");
+	       info->name, info->nr_channels, info->nr_channels > 1 ? "s" : "");
 
 	BUG_ON((info->flags & DMAC_CHANNELS_CONFIGURED) && !info->channels);
 
@@ -242,28 +362,26 @@ int register_dmac(struct dma_info *info)
 
 		size = sizeof(struct dma_channel) * info->nr_channels;
 
-		info->channels = kmalloc(size, GFP_KERNEL);
+		info->channels = kzalloc(size, GFP_KERNEL);
 		if (!info->channels)
 			return -ENOMEM;
-
-		memset(info->channels, 0, size);
 	}
 
 	total_channels = get_nr_channels();
 	for (i = 0; i < info->nr_channels; i++) {
-		struct dma_channel *chan = info->channels + i;
+		struct dma_channel *chan = &info->channels[i];
+
+		atomic_set(&chan->busy, 0);
 
-		chan->chan = i;
-		chan->vchan = i + total_channels;
+		chan->chan  = info->first_channel_nr + i;
+		chan->vchan = info->first_channel_nr + i + total_channels;
 
 		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);
-
 		dma_create_sysfs_files(chan, info);
 	}
 
@@ -271,6 +389,7 @@ int register_dmac(struct dma_info *info)
 
 	return 0;
 }
+EXPORT_SYMBOL(register_dmac);
 
 void unregister_dmac(struct dma_info *info)
 {
@@ -285,31 +404,16 @@ void unregister_dmac(struct dma_info *info)
 	list_del(&info->list);
 	platform_device_unregister(info->pdev);
 }
+EXPORT_SYMBOL(unregister_dmac);
 
 static int __init dma_api_init(void)
 {
-	printk("DMA: Registering DMA API.\n");
-
-#ifdef CONFIG_PROC_FS
+	printk(KERN_NOTICE "DMA: Registering DMA API.\n");
 	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);
-

include/asm-sh/dma.h

@@ -14,9 +14,7 @@
 #include <linux/spinlock.h>
 #include <linux/wait.h>
 #include <linux/sysdev.h>
-#include <linux/device.h>
 #include <asm/cpu/dma.h>
-#include <asm/semaphore.h>
 
 /* The maximum address that we can perform a DMA transfer to on this platform */
 /* Don't define MAX_DMA_ADDRESS; it's useless on the SuperH and any
@@ -46,16 +44,21 @@
  * DMAC (dma_info) flags
  */
 enum {
-	DMAC_CHANNELS_CONFIGURED	= 0x00,
-	DMAC_CHANNELS_TEI_CAPABLE	= 0x01,
+	DMAC_CHANNELS_CONFIGURED	= 0x01,
+	DMAC_CHANNELS_TEI_CAPABLE	= 0x02,	/* Transfer end interrupt */
 };
 
 /*
  * DMA channel capabilities / flags
  */
 enum {
-	DMA_TEI_CAPABLE			= 0x01,
-	DMA_CONFIGURED			= 0x02,
+	DMA_CONFIGURED			= 0x01,
+
+	/*
+	 * Transfer end interrupt, inherited from DMAC.
+	 * wait_queue used in dma_wait_for_completion.
+	 */
+	DMA_TEI_CAPABLE			= 0x02,
 };
 
 extern spinlock_t dma_spin_lock;
@@ -68,28 +71,31 @@ struct dma_ops {
 
 	int (*get_residue)(struct dma_channel *chan);
 	int (*xfer)(struct dma_channel *chan);
-	void (*configure)(struct dma_channel *chan, unsigned long flags);
+	int (*configure)(struct dma_channel *chan, unsigned long flags);
+	int (*extend)(struct dma_channel *chan, unsigned long op, void *param);
 };
 
 struct dma_channel {
-	char dev_id[16];
+	char dev_id[16];		/* unique name per DMAC of channel */
 
-	unsigned int chan;		/* Physical channel number */
+	unsigned int chan;		/* DMAC channel number */
 	unsigned int vchan;		/* Virtual channel number */
+
 	unsigned int mode;
 	unsigned int count;
 
 	unsigned long sar;
 	unsigned long dar;
 
+	const char **caps;
+
 	unsigned long flags;
 	atomic_t busy;
 
-	struct semaphore sem;
 	wait_queue_head_t wait_queue;
 
 	struct sys_device dev;
-	char *name;
+	void *priv_data;
 };
 
 struct dma_info {
@@ -103,6 +109,12 @@ struct dma_info {
 	struct dma_channel *channels;
 
 	struct list_head list;
+	int first_channel_nr;
+};
+
+struct dma_chan_caps {
+	int ch_num;
+	const char **caplist;
 };
 
 #define to_dma_channel(channel) container_of(channel, struct dma_channel, dev)
@@ -121,6 +133,8 @@ extern int dma_xfer(unsigned int chan, unsigned long from,
 #define dma_read_page(chan, from, to)	\
 	dma_read(chan, from, to, PAGE_SIZE)
 
+extern int request_dma_bycap(const char **dmac, const char **caps,
+			     const char *dev_id);
 extern int request_dma(unsigned int chan, const char *dev_id);
 extern void free_dma(unsigned int chan);
 extern int get_dma_residue(unsigned int chan);
@@ -131,6 +145,10 @@ extern void dma_configure_channel(unsigned int chan, unsigned long flags);
 
 extern int register_dmac(struct dma_info *info);
 extern void unregister_dmac(struct dma_info *info);
+extern struct dma_info *get_dma_info_by_name(const char *dmac_name);
+
+extern int dma_extend(unsigned int chan, unsigned long op, void *param);
+extern int register_chan_caps(const char *dmac, struct dma_chan_caps *capslist);
 
 #ifdef CONFIG_SYSFS
 /* arch/sh/drivers/dma/dma-sysfs.c */