Staging: poch: Fetch Flush IOCTL interface

Change user space interface to an IOCTL based interface instead of a
memory mapped circular buffer. The circular buffer had some serious
cache(?) issues and never worked.

Signed-off-by: Vijay Kumar B. <vijaykumar@bravegnu.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 65 insertions, 2 deletions

diff --git a/drivers/staging/poch/poch.c b/drivers/staging/poch/poch.c
index 1308c7bada8..6b4aa5f1d51 100644
--- a/drivers/staging/poch/poch.c
+++ b/drivers/staging/poch/poch.c
@@ -201,6 +201,8 @@ struct channel_info {
         struct page *header_pg;
         unsigned long header_size;
 
+        /* Last group consumed by user space. */
+        unsigned int consumed;
         /* Last group indicated as 'complete' to user space. */
         unsigned int transfer;
 
@@ -589,6 +591,7 @@ static int poch_channel_init(struct channel_info *channel,
         if (ret != 0)
                 goto out;
 
+        channel->consumed = 0;
         channel->transfer = 0;
 
         /* Allocate memory to hold group information. */
@@ -1033,6 +1036,51 @@ static int poch_ioctl(struct inode *inode, struct file *filp,
                         break;
                 }
                 break;
+        case POCH_IOC_CONSUME:
+        {
+                int available;
+                int nfetch;
+                unsigned int from;
+                unsigned int count;
+                unsigned int i, j;
+                struct poch_consume consume;
+                struct poch_consume *uconsume;
+
+                uconsume = argp;
+                ret = copy_from_user(&consume, uconsume, sizeof(consume));
+                if (ret)
+                        return ret;
+
+                spin_lock_irq(&channel->group_offsets_lock);
+
+                channel->consumed += consume.nflush;
+                channel->consumed %= channel->group_count;
+
+                available = channel->transfer - channel->consumed;
+                if (available < 0)
+                        available += channel->group_count;
+
+                from = channel->consumed;
+
+                spin_unlock_irq(&channel->group_offsets_lock);
+
+                nfetch = consume.nfetch;
+                count = min(available, nfetch);
+
+                for (i = 0; i < count; i++) {
+                        j = (from + i) % channel->group_count;
+                        ret = put_user(channel->groups[j].user_offset,
+                                       &consume.offsets[i]);
+                        if (ret)
+                                return -EFAULT;
+                }
+
+                ret = put_user(count, &uconsume->nfetch);
+                if (ret)
+                        return -EFAULT;
+
+                break;
+        }
         case POCH_IOC_GET_COUNTERS:
                 if (!access_ok(VERIFY_WRITE, argp, sizeof(struct poch_counters)))
                         return -EFAULT;
@@ -1108,12 +1156,18 @@ static void poch_irq_dma(struct channel_info *channel)
         for (i = 0; i < groups_done; i++) {
                 j = (prev_transfer + i) % channel->group_count;
                 group_offsets[j] = groups[j].user_offset;
+
+                channel->transfer += 1;
+                channel->transfer %= channel->group_count;
+
+                if (channel->transfer == channel->consumed) {
+                        channel->consumed += 1;
+                        channel->consumed %= channel->group_count;
+                }
         }
 
         spin_unlock(&channel->group_offsets_lock);
 
-        channel->transfer = curr_transfer;
-
         wake_up_interruptible(&channel->wq);
 }
 
diff --git a/drivers/staging/poch/poch.h b/drivers/staging/poch/poch.h
index 51a2d145798..ba1490b4252 100644
--- a/drivers/staging/poch/poch.h
+++ b/drivers/staging/poch/poch.h
@@ -19,6 +19,12 @@ struct poch_counters {
         __u32 pll_unlock;
 };
 
+struct poch_consume {
+        __u32 __user *offsets;
+        __u32 nfetch;
+        __u32 nflush;
+};
+
 #define POCH_IOC_NUM                    '9'
 
 #define POCH_IOC_TRANSFER_START         _IO(POCH_IOC_NUM, 0)
@@ -27,3 +33,6 @@ struct poch_counters {
                                              struct poch_counters)
 #define POCH_IOC_SYNC_GROUP_FOR_USER    _IO(POCH_IOC_NUM, 3)
 #define POCH_IOC_SYNC_GROUP_FOR_DEVICE  _IO(POCH_IOC_NUM, 4)
+
+#define POCH_IOC_CONSUME                _IOWR(POCH_IOC_NUM, 5, \
+                                              struct poch_consume)