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>
diff --git a/arch/sh/drivers/dma/dma-api.c b/arch/sh/drivers/dma/dma-api.c
index 47c3e83..e062067 100644
--- a/arch/sh/drivers/dma/dma-api.c
+++ b/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, ®istered_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 @@
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, ®istered_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 @@
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;
- 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);
+ 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, ®istered_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;
+ }
+
+ if (info->ops->request) {
+ int result = info->ops->request(channel);
+ if (result)
+ return result;
+
+ atomic_set(&channel->busy, 1);
+ return channel->chan;
+ }
+
+ 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));
+
+ if (info->ops->request) {
+ result = info->ops->request(channel);
+ if (result)
+ atomic_set(&channel->busy, 0);
+
+ 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 @@
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, ®istered_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 @@
return info->ops->xfer(channel);
}
+EXPORT_SYMBOL(dma_xfer);
-#ifdef CONFIG_PROC_FS
+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);
+
static int dma_read_proc(char *buf, char **start, off_t off,
int len, int *eof, void *data)
{
@@ -214,8 +337,6 @@
return p - buf;
}
-#endif
-
int register_dmac(struct dma_info *info)
{
@@ -224,8 +345,7 @@
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 @@
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];
- chan->chan = i;
- chan->vchan = i + total_channels;
+ atomic_set(&chan->busy, 0);
+
+ 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 @@
return 0;
}
+EXPORT_SYMBOL(register_dmac);
void unregister_dmac(struct dma_info *info)
{
@@ -285,31 +404,16 @@
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);
-