platform-drivers: msm: sps: return number of unused descriptors

Client driver has a new feature requirement to acquire the number
of unused descriptors in the descriptor FIFO of a pipe; Add this
support in SPS driver.

Change-Id: Idf02308f6011973c2ad4fea2a50134b48062b953
Signed-off-by: Yan He <yanhe@codeaurora.org>

arch/arm/mach-msm/include/mach/sps.h

@@ -1205,4 +1205,17 @@ int sps_phy2h(u32 phys_addr, u32 *handle);
 int sps_setup_bam2bam_fifo(struct sps_mem_buffer *mem_buffer,
 		  u32 addr, u32 size, int use_offset);
 
+/**
+ * Get the number of unused descriptors in the descriptor FIFO
+ * of a pipe
+ *
+ * @h - client context for SPS connection end point
+ *
+ * @desc_num - number of unused descriptors
+ *
+ * @return 0 on success, negative value on error
+ *
+ */
+int sps_get_unused_desc_num(struct sps_pipe *h, u32 *desc_num);
+
 #endif /* _SPS_H_ */

drivers/platform/msm/sps/sps.c

@@ -1351,6 +1351,32 @@ int sps_free_mem(struct sps_pipe *h, struct sps_mem_buffer *mem_buffer)
 }
 EXPORT_SYMBOL(sps_free_mem);
 
+/**
+ * Get the number of unused descriptors in the descriptor FIFO
+ * of a pipe
+ *
+ */
+int sps_get_unused_desc_num(struct sps_pipe *h, u32 *desc_num)
+{
+	struct sps_pipe *pipe = h;
+	struct sps_bam *bam;
+	int result;
+
+	SPS_DBG("sps:%s.", __func__);
+
+	bam = sps_bam_lock(pipe);
+	if (bam == NULL)
+		return SPS_ERROR;
+
+	result = sps_bam_pipe_get_unused_desc_num(bam, pipe->pipe_index,
+						desc_num);
+
+	sps_bam_unlock(bam);
+
+	return result;
+}
+EXPORT_SYMBOL(sps_get_unused_desc_num);
+
 /**
  * Register a BAM device
  *

drivers/platform/msm/sps/sps_bam.c

@@ -1960,3 +1960,29 @@ int sps_bam_pipe_timer_ctrl(struct sps_bam *dev,
 	return result;
 }
 
+/**
+ * Get the number of unused descriptors in the descriptor FIFO
+ * of a pipe
+ */
+int sps_bam_pipe_get_unused_desc_num(struct sps_bam *dev, u32 pipe_index,
+					u32 *desc_num)
+{
+	u32 sw_offset, peer_offset, fifo_size;
+	u32 desc_size = sizeof(struct sps_iovec);
+	struct sps_pipe *pipe = dev->pipes[pipe_index];
+
+	if (pipe == NULL)
+		return SPS_ERROR;
+
+	fifo_size = pipe->desc_size;
+
+	sw_offset = bam_pipe_get_desc_read_offset(dev->base, pipe_index);
+	peer_offset = bam_pipe_get_desc_write_offset(dev->base, pipe_index);
+
+	if (sw_offset <= peer_offset)
+		*desc_num = (peer_offset - sw_offset) / desc_size;
+	else
+		*desc_num = (peer_offset + fifo_size - sw_offset) / desc_size;
+
+	return 0;
+}

drivers/platform/msm/sps/sps_bam.h

@@ -545,4 +545,20 @@ int sps_bam_set_satellite(struct sps_bam *dev, u32 pipe_index);
 int sps_bam_pipe_timer_ctrl(struct sps_bam *dev, u32 pipe_index,
 			    struct sps_timer_ctrl *timer_ctrl,
 			    struct sps_timer_result *timer_result);
+
+
+/**
+ * Get the number of unused descriptors in the descriptor FIFO
+ * of a pipe
+ *
+ * @dev - pointer to BAM device descriptor
+ *
+ * @pipe_index - pipe index
+ *
+ * @desc_num - number of unused descriptors
+ *
+ */
+int sps_bam_pipe_get_unused_desc_num(struct sps_bam *dev, u32 pipe_index,
+					u32 *desc_num);
+
 #endif	/* _SPSBAM_H_ */