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>

1 files changed, 189 insertions, 85 deletions

diff --git a/arch/sh/drivers/dma/dma-api.c b/arch/sh/drivers/dma/dma-api.c
index 47c3e837599b..e062067edd24 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, &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);
-