sh: dma-api channel capability extensions.
Mark Glaisher [Fri, 24 Nov 2006 06:13:52 +0000 (15:13 +0900)]
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
include/asm-sh/dma.h

index 47c3e83..e062067 100644 (file)
  */
 #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);
-
index d9daa02..faf3051 100644 (file)
@@ -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
  * 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 */