Add multichannel support to circbuf.c, fix formatting

src/drivers/elphel/circbuf.c

 /** @file circbuf.c
  *
- * @brief drivers to manipulate large circular buffer that holds compressed
+ * @brief Drivers to manipulate large circular buffer that holds compressed
  * images/video. Buffer frame data is filled in by the FPGA, frame pointers and
  * essential frames metadata filled during servicing of the interrupts.
  *
@@ -71,20 +71,17 @@
 #include "x393_macro.h"
 #include "x393.h"
 
+#define CIRCBUF_DRIVER_NAME "circbuf driver"
+
+/** Wait queue for the processes waiting for a new frame to appear in the circular buffer */
+wait_queue_head_t circbuf_wait_queue;
+
 struct circbuf_priv_t circbuf_priv[IMAGE_CHN_NUM];
 struct circbuf_priv_t *circbuf_priv_ptr = circbuf_priv;
 
 static struct device *g_dev_ptr;
 
 static const struct of_device_id elphel393_circbuf_of_match[];
-/* really huge static DMA buffer (1288+8)*1032/3=445824 long-s */
-// DMA_SIZE - in 32-bit words, not bytes
-//static unsigned long ccam_dma_buf[CCAM_DMA_SIZE + (PAGE_SIZE>>2)] __attribute__ ((aligned (PAGE_SIZE)));
-static unsigned long *ccam_dma_buf = NULL;
-//!Without "static" system hangs after "Uncompressing Linux...
-unsigned long  * ccam_dma_buf_ptr = NULL;
-//EXPORT_SYMBOL_GPL(ccam_dma_buf_ptr);
-//unsigned long * ccam_dma =         NULL; //! still used in autoexposure or something - why is in needed there?
 
 int init_ccam_dma_buf_ptr(struct platform_device *pdev)
 {
@@ -92,8 +89,7 @@ int init_ccam_dma_buf_ptr(struct platform_device *pdev)
 	dma_addr_t dma_handle;
 	const size_t dma_size = (CCAM_DMA_SIZE + (PAGE_SIZE >> 2)) * sizeof(int);
 	struct device *dev = &pdev->dev;
-	//ccam_dma_buf_ptr = ccam_dma_buf;
-	//ccam_dma =         ccam_dma_buf; //&ccam_dma_buf[0]; Use in autoexposure
+	unsigned long *ccam_dma_buf_ptr = NULL;
 
 	// use Elphel_buf if it was allocated
 	if (pElphel_buf != NULL) {
@@ -109,10 +105,8 @@ int init_ccam_dma_buf_ptr(struct platform_device *pdev)
 			dev_info(dev, "%d bytes of DMA memory allocated at address 0x%08p", dma_size , dma_handle);
 		}
 	}
-	ccam_dma_buf = ccam_dma_buf_ptr;
 
-	// set circbuf size in bytes
-	//set_globalParam(G_CIRCBUFSIZE, pElphel_buf->size * PAGE_SIZE);
+	// set circular buffer size in bytes
 	set_globalParam(G_CIRCBUFSIZE, CCAM_DMA_SIZE);
 
 	for (i = 0; i < IMAGE_CHN_NUM; i++) {
@@ -123,231 +117,189 @@ int init_ccam_dma_buf_ptr(struct platform_device *pdev)
 	return 0;
 }
 
-static inline unsigned int minor_to_chn(int minor)
+/**
+ * @brief Converts file minor number to image compressor channel.
+ *
+ * This function assumes that the least significant nibble of minor contains image compressor channel number and
+ * next nibble contains device type. Channel numbers and device type are defined in #driver_numbers.h
+ * @param[in]   minor     file minor number
+ * @param[out]  dev_type  pointer to a variable which will hold device type or NULL if this value is not needed
+ * @return      compressor channel number in the range [0..#IMAGE_CHN_NUM)
+ */
+static inline unsigned int minor_to_chn(unsigned int minor, unsigned int *dev_type)
 {
-	//return minor - CIRCBUF_MINOR_CHN_OFFSET;
-	return 0;
+	if (dev_type != NULL) {
+		if ((minor & 0xf0) == CIRCBUF_MINOR || (minor & 0xf0) == HUFFMAN_MINOR || (minor & 0xf0) == JPEGHEAD_MINOR)
+			*dev_type = minor & 0xf0;
+		else
+			*dev_type = 0;
+	}
+	if ((minor & 0x0f) < IMAGE_CHN_NUM)
+		return minor & 0x0f;
+	else
+		return 0;
 }
 
-//extern struct interframe_params_t frame_params; // cc353.c
-/*!======================================================================================
- *! Wait queue for the processes waiting for a new frame to appear in the circular buffer
- *!======================================================================================*/
-wait_queue_head_t circbuf_wait_queue;
-/*!=========================================================================================================
- *! circbuf top level device drivers. Minors are the same as before
- *! CMOSCAM_MINOR_CIRCBUF, CMOSCAM_MINOR_JPEAGHEAD - just a new major
- *!========================================================================================================*/
-#define CIRCBUF_DRIVER_NAME "Elphel (R) Model 353 video buffer device driver"
-
-// Read/write to circular buffer.  Needed to find out what Axis DMA is doing
-// also - jpeg header
-struct circbuf_pd {
-    int       minor;        /// should be the first, same as in jpeghead_pd
-    int       daemon_bit;   /// poll() will produce POLLHUP if this bit is >=0 (set through lseek (, LSEEK_DAEMON_CIRCBUF,SEEK_END)
-                            /// and the corresponding bit in P_DAEMON_EN goes 0
-    int       imageWidth;   /// image width to compare to current. G_SKIP_DIFF_FRAME
-    int       imageHeight;  /// image height to compare to current. G_SKIP_DIFF_FRAME
-    int       tolerated;    /// number of frames with different size tolerated
-    struct wait_queue *circbuf_wait_queue; ///NOTE: not used at all?
-// something else to be added here?
-};
-
-
-// CMOSCAM_MINOR_HUFFMAN // huffman tables R/W
 int circbuf_all_open(struct inode *inode, struct file *filp)
 {
 	int res;
-	int minor = MINOR(inode->i_rdev);
+	unsigned int minor = MINOR(inode->i_rdev);
+	unsigned int dev_type;
 	dev_dbg(g_dev_ptr, "circbuf_all_open, minor = 0x%x\n", minor);
 
-	switch (MINOR(inode->i_rdev)) {
-	case  CMOSCAM_MINOR_CIRCBUF :
-		res=circbuf_open(inode,filp);
+	minor_to_chn(minor, &dev_type);
+	switch (dev_type) {
+	case CIRCBUF_MINOR:
+		res = circbuf_open(inode, filp);
 		break;
-	case  CMOSCAM_MINOR_JPEAGHEAD :
-		res=jpeghead_open(inode,filp);
+	case JPEGHEAD_MINOR:
+		res = jpeghead_open(inode, filp);
 		break;
-	case  CMOSCAM_MINOR_HUFFMAN :
-		res=huffman_open(inode,filp);
+	case HUFFMAN_MINOR:
+		res = huffman_open(inode, filp);
 		break;
 	default:
-		//       kfree(filp->private_data); // already allocated
 		return -EINVAL;
 	}
 	return res;
 }
 
-int circbuf_all_release(struct inode *inode, struct file *filp) {
-  int res=0;
-  int p = MINOR(inode->i_rdev);
- dev_dbg(g_dev_ptr, "minor = 0x%x\n", p);
-  switch ( p ) {
-    case  CMOSCAM_MINOR_CIRCBUF :
-//        res=circbuf_release(inode,filp);
-        break;
-    case  CMOSCAM_MINOR_JPEAGHEAD :
-//        res=jpeghead_release(inode,filp);
-        break;
-    case  CMOSCAM_MINOR_HUFFMAN :
-//        res=huffman_release(inode,filp);
-        break;
-    default:
-        return -EINVAL; //! do not need to free anything - "wrong number"
-    }
-  if (filp->private_data) kfree(filp->private_data);
-  return res;
+int circbuf_all_release(struct inode *inode, struct file *filp)
+{
+	int res=0;
+	unsigned int minor = MINOR(inode->i_rdev);
+	unsigned int dev_type;
+	dev_dbg(g_dev_ptr, "minor = 0x%x\n", minor);
+
+	minor_to_chn(minor, &dev_type);
+	switch (dev_type) {
+	case CIRCBUF_MINOR:
+		//        res=circbuf_release(inode,filp);
+		break;
+	case JPEGHEAD_MINOR:
+		//        res=jpeghead_release(inode,filp);
+		break;
+	case HUFFMAN_MINOR:
+		//        res=huffman_release(inode,filp);
+		break;
+	default:
+		return -EINVAL;
+	}
+	if (filp->private_data) kfree(filp->private_data);
+	return res;
 }
 
-loff_t circbuf_all_lseek(struct file * file, loff_t offset, int orig)
+loff_t circbuf_all_lseek(struct file *file, loff_t offset, int orig)
 {
-	struct circbuf_pd * privData;
-	privData = (struct circbuf_pd *) file->private_data;
-	struct interframe_params_t *fp = NULL;
 	int rp;
-	int minor = privData->minor;
-
+	struct interframe_params_t *fp = NULL;
+	unsigned int minor = MINOR(file->f_inode->i_rdev);
+	unsigned int dev_type;
+	unsigned int chn = minor_to_chn(minor, &dev_type);
 	dev_dbg(g_dev_ptr, "circbuf_all_lseek, minor = 0x%x\n", minor);
-	switch (minor) {
-	case CMOSCAM_MINOR_CIRCBUF :
+
+	switch (dev_type) {
+	case CIRCBUF_MINOR:
 		return  circbuf_lseek(file, offset, orig);
-	case CMOSCAM_MINOR_JPEAGHEAD :
+	case JPEGHEAD_MINOR:
 		if (orig == SEEK_END && offset > 0) {
 			rp = BYTE2DW(offset) & (~7); // convert to index to long, align to 32-bytes
-			//fp = (struct interframe_params_t *) &ccam_dma_buf_ptr[X313_BUFFSUB(rp, 8)]; //! 32 bytes before the frame pointer, may roll-over to the end of ccam_dma_buf_ptr
-			fp = (struct interframe_params_t *) &circbuf_priv[minor_to_chn(minor)].buf_ptr[X393_BUFFSUB(rp, 8)];
+			fp = (struct interframe_params_t *) &circbuf_priv[chn].buf_ptr[X393_BUFFSUB(rp, 8)];
 		}
 		return  jpeghead_lseek(file, offset, orig, fp);
-	case CMOSCAM_MINOR_HUFFMAN :
+	case HUFFMAN_MINOR:
 		return  huffman_lseek(file, offset, orig);
 	default:
 		return -EINVAL;
 	}
 }
 
-ssize_t circbuf_all_read(struct file * file, char * buf, size_t count, loff_t *off) {
-     struct circbuf_pd * privData;
-     privData = (struct circbuf_pd *) file->private_data;
- dev_dbg(g_dev_ptr, "minor = 0x%x\n", privData->minor);
-     switch (privData->minor) {
-       case CMOSCAM_MINOR_CIRCBUF :      return  circbuf_read   (file, buf, count, off);
-       case CMOSCAM_MINOR_JPEAGHEAD :    return  jpeghead_read  (file, buf, count, off);
-       case CMOSCAM_MINOR_HUFFMAN :      return  huffman_read  (file, buf, count, off);
-       default:                          return -EINVAL;
-    }
-}
-ssize_t circbuf_all_write(struct file * file, const char * buf, size_t count, loff_t *off) {
-     struct circbuf_pd * privData;
-     privData = (struct circbuf_pd *) file->private_data;
- dev_dbg(g_dev_ptr, "minor = 0x%x, count = %d, off = %d\n", privData->minor, (int)count, (int)*off);
-     switch (privData->minor) {
-       case CMOSCAM_MINOR_CIRCBUF :       return  circbuf_write  (file, buf, count, off);
-//       case CMOSCAM_MINOR_JPEAGHEAD :     return  jpeghead_write (file, buf, count, off); // same as other - write header
-       case CMOSCAM_MINOR_HUFFMAN :       return  huffman_write  (file, buf, count, off);
-       default:                           return -EINVAL;
-    }
-}
-
-
-int circbuf_all_mmap (struct file *file, struct vm_area_struct *vma) {
-     struct circbuf_pd * privData;
-     privData = (struct circbuf_pd *) file->private_data;
- dev_dbg(g_dev_ptr, "minor = 0x%x\n", privData->minor);
-     switch (privData->minor) {
-       case  CMOSCAM_MINOR_CIRCBUF :   return  circbuf_mmap   (file, vma);
-       default: return -EINVAL;
-    }
-}
+ssize_t circbuf_all_read(struct file *file, char *buf, size_t count, loff_t *off)
+{
+	unsigned int minor = MINOR(file->f_inode->i_rdev);
+	unsigned int dev_type;
+	dev_dbg(g_dev_ptr, "minor = 0x%x\n", minor);
 
-unsigned int circbuf_all_poll (struct file *file, poll_table *wait) {
-     struct circbuf_pd * privData;
-     privData = (struct circbuf_pd *) file->private_data;
- dev_dbg(g_dev_ptr, "minor = 0x%x\n", privData->minor);
-     switch (privData->minor) {
-       case  CMOSCAM_MINOR_CIRCBUF :
-          return circbuf_poll (file, wait);
-       default:                           return -EINVAL;
-    }
+	minor_to_chn(minor, &dev_type);
+	switch (dev_type) {
+	case CIRCBUF_MINOR:
+		return circbuf_read(file, buf, count, off);
+	case JPEGHEAD_MINOR:
+		return jpeghead_read(file, buf, count, off);
+	case HUFFMAN_MINOR:
+		return huffman_read(file, buf, count, off);
+	default:
+		return -EINVAL;
+	}
 }
 
-int circbuf_all_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg) {
-     struct circbuf_pd * privData;
-     privData = (struct circbuf_pd *) filp->private_data;
-     printk("\n========== IOCTL is not implemented in circbuf_all_ioctl, minor=0x%x, cmd=0x%x, _IOC_NR(cmd)=0x%x, arg=0x%x\n",privData-> minor, (int) cmd, _IOC_NR(cmd), (int) arg);
-     return -EINVAL;
+ssize_t circbuf_all_write(struct file *file, const char *buf, size_t count, loff_t *off)
+{
+	unsigned int minor = MINOR(file->f_inode->i_rdev);
+	unsigned int dev_type;
+	dev_dbg(g_dev_ptr, "minor = 0x%x, count = %d, off = %d\n", minor, (int)count, (int)*off);
+
+	minor_to_chn(minor, &dev_type);
+	switch (dev_type) {
+	case CIRCBUF_MINOR:
+		return circbuf_write (file, buf, count, off);
+	case JPEGHEAD_MINOR:
+		// no method for this module
+		return -EINVAL;
+	case HUFFMAN_MINOR:
+		return huffman_write (file, buf, count, off);
+	default:
+		return -EINVAL;
+	}
 }
 
+int circbuf_all_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	unsigned int minor = MINOR(file->f_inode->i_rdev);
+	unsigned int dev_type;
+	dev_dbg(g_dev_ptr, "minor = 0x%x\n", minor);
 
+	minor_to_chn(minor, &dev_type);
+	switch (dev_type) {
+	case CIRCBUF_MINOR:
+		return circbuf_mmap(file, vma);
+	default:
+		return -EINVAL;
+	}
+}
 
+unsigned int circbuf_all_poll (struct file *file, poll_table *wait)
+{
+	unsigned int minor = MINOR(file->f_inode->i_rdev);
+	unsigned int dev_type;
+	dev_dbg(g_dev_ptr, "minor = 0x%x\n", minor);
 
-int circbuf_open(struct inode *inode, struct file *filp) { // set filesize
-   struct circbuf_pd * privData;
-   privData= (struct circbuf_pd *) kmalloc(sizeof(struct circbuf_pd),GFP_KERNEL);
-   if (!privData) return -ENOMEM;
-   filp->private_data = privData;
-   privData-> minor=MINOR(inode->i_rdev);
+	minor_to_chn(minor, &dev_type);
+	switch (dev_type) {
+	case CIRCBUF_MINOR:
+		return circbuf_poll(file, wait);
+	default:
+		return -EINVAL;
+	}
+}
 
-   //inode->i_size = ((CCAM_DMA_SIZE) << 2);
-   inode->i_size = CCAM_DMA_SIZE;
-   dev_dbg(g_dev_ptr, "inode->i_size = 0x%x\n");
+int circbuf_open(struct inode *inode, struct file *filp)
+{
+	inode->i_size = CCAM_DMA_SIZE;
+	dev_dbg(g_dev_ptr, "inode->i_size = 0x%x\n");
 
-//!should be removed (or else you can not ftp file - it will start from WP)
-//   circbuf_lseek(filp, LSEEK_CIRC_LAST, SEEK_END); //! position at last acquired frame, ignore result
-   return 0;
+	return 0;
 }
 
-/*!=============================================================================================
- *! Overloading lseek with additional functionality (to avoid ioctls)
- *! with orig==SEEK_END lseek will treat (offset>0) as a command
- *! to manipulate frame pointer(s) or wait for the image to be ready
- *! using these commands
- *!  LSEEK_CIRC_TORP .- set filepointer to global (shared) read pointer
- *!  LSEEK_CIRC_TOWP  - set filepointer to FPGA write pointer (next frame to be acquired)
- *!  LSEEK_CIRC_PREV  - move pointer to the previous frame, return -EOVERFLOW if there are none
- *!  LSEEK_CIRC_NEXT  - advance pointer to the next frame, return -EOVERFLOW if was already
- *!      at the last
- *!  LSEEK_CIRC_LAST  - move pointer to the last acquired frame (default after open)
- *!      (it is combination of 2+3)
- *!  LSEEK_CIRC_FIRST - move pointer to the first acquired frame. It s not safe to rely
- *!                    on this pointer if more frames are expected - next incoming frame
- *!                    can overwrite this one.
- *!  LSEEK_CIRC_SCND -  move pointer to the second oldest acquired frame. A slightly safer
- *!                    to use instead of LSEEK_CIRC_FIRST when constant acquisition is on
- *!                    and sensor provides new frames - this frame will likely survive longer
- *!  LSEEK_CIRC_SETP -  save current pointer to global read pointer
- *!  LSEEK_CIRC_VALID - verify that the frame at current location is valid (not overrun in the buffer)
- *!                    Returns file pointer if valid, else - -1
- *!  LSEEK_CIRC_READY - verify frame at current loacation is available (valid and acquired)
- *!                    Returns file pointer if ready, else - -1
- *!  LSEEK_CIRC_WAIT - sleep until next frame is acquired 
- *! All commands but (LSEEK_CIRC_TOWP,LSEEK_CIRC_LAST,LSEEK_CIRC_FIRST) will return -EINVAL if read 
- *! pointer is not valid  (i.e buffer was overrun and data pointed is lost). if success they return
- *! the current (byte *) to the start of the frame data (parameters are at
- *! offsett =-32 from it)
- *! (0, SEEK_CUR) also verifies that the header is not overwritten. It can be used
- *! after buffering frame data to verify you got it all correctly
- *! SEEK_CUR also supports the circular nature of the buffer and rolls over if needed
- *! Additional commands for SEEK_END (they _DO_ modify the current file pointer !)
- *!  LSEEK_CIRC_FREE - returnes remaining memory in circbuf from the current file pointer,
- *!                   or -EINVAL if the pointer is invalid. As this command uses the buffer write pointer
- *!                   that is updated only when the complete frame is in the buffer, the actual
- *!                   free memory may be less by a whole frame if compressor is running.
- *!  LSEEK_CIRC_USED - returnes memory used in the in circbuf from the current file pointer,
- *!                   or -EINVAL if the pointer is invalid
- *!=============================================================================================*/
-//!returns 0 if rp is a valid read ponter
-//! returns 1 if there is a frame at this address
-//! returns 0 if the pointer is for the frame yet to be acquired
-//! returns -1 if there is no frame at this index
-//! returns -2 if the rp is not 32-bytes aligned
-//!sets *fpp to the frame header, including signature and length
-
 void dump_interframe_params(struct interframe_params_t *params, int offset)
 {
 	dev_dbg(g_dev_ptr, "Dump of interframe parameters at offset 0x%x:\n", offset);
 	print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, params, sizeof(struct interframe_params_t));
 }
 
+/**
+ * @brief
+ */
 unsigned long get_image_length(int byte_offset, unsigned int chn, int *last_chunk_offset)
 {
 	unsigned long len32;
@@ -365,8 +317,17 @@ unsigned long get_image_length(int byte_offset, unsigned int chn, int *last_chun
 	return len32;
 }
 
-// rp is byte offset
-int circbufValidPointer(int rp, struct interframe_params_t ** fpp, unsigned int chn)
+/**
+ * @brief Check that read pointer is valid
+ * @param[in]   rp   read pointer to be checked; this pointer is in bytes
+ * @param[out]  fpp  pointer to #interframe_params_t structure, this pointer will be set to
+ * frame header before \e rp and will point to its parameters
+ * @param[in]   chn  specify compressor channel number which pointer should be checked
+ * @return 0 if the pointer is for the frame yet to be acquired, 1 if there is a valid frame at this address,
+ * -1 if there is no frame at this index, -2 if the pointer is not 32-bytes aligned
+ * sets *fpp to the frame header, including signature and length
+ */
+int circbuf_valid_ptr(int rp, struct interframe_params_t **fpp, unsigned int chn)
 {
 	int last_image_chunk;
 	unsigned int sec;
@@ -375,7 +336,8 @@ int circbufValidPointer(int rp, struct interframe_params_t ** fpp, unsigned int
 	unsigned int len32 = get_image_length(DW2BYTE(wp), chn, &last_image_chunk);
 	struct interframe_params_t *fp;
 
-	if (rp & 0x1f) {  //!rp is not 32-bytes aligned
+	if (rp & 0x1f) {
+		// rp is not 32-bytes aligned
 		dev_dbg(g_dev_ptr, "misaligned pointer rp = 0x%x for channel %d\n", rp, chn);
 		return -2;
 	}
@@ -396,205 +358,241 @@ int circbufValidPointer(int rp, struct interframe_params_t ** fpp, unsigned int
 	return 1;
 }
 
-loff_t circbuf_lseek(struct file * file, loff_t offset, int orig) {
-	unsigned int len32;
+/**
+ * @brief Reposition read/write file offset
+ *
+ * This function is overloaded with additional functionality in order to avoid ioctls.
+ * In case user-space program set <em>orig == SEEK_END</em>, \e lseek will treat (offset > 0) as a command
+ * to manipulate frame pointer(s) or wait for the image to be ready using these commands:
+ *
+ *  LSEEK_CIRC_TORP  - set file pointer to global (shared) read pointer;
+ *  LSEEK_CIRC_TOWP  - set file pointer to FPGA write pointer (next frame to be acquired);
+ *  LSEEK_CIRC_PREV  - move pointer to the previous frame, return \e -EOVERFLOW if there are none;
+ *  LSEEK_CIRC_NEXT  - advance pointer to the next frame, return \e -EOVERFLOW if it was at the last frame
+ *  LSEEK_CIRC_LAST  - move pointer to the last acquired frame (default after open), this is a combination
+ *                     of LSEEK_CIRC_TOWP and LSEEK_CIRC_PREV;
+ *  LSEEK_CIRC_FIRST - move pointer to the first acquired frame. It s not safe to rely
+ *                     on this pointer if more frames are expected - next incoming frame
+ *                     can overwrite this one;
+ *  LSEEK_CIRC_SCND -  move pointer to the second oldest acquired frame. A slightly safer
+ *                     to use instead of LSEEK_CIRC_FIRST when constant acquisition is on
+ *                     and sensor provides new frames - this frame will likely survive longer;
+ *  LSEEK_CIRC_SETP -  save current pointer to global read pointer
+ *  LSEEK_CIRC_VALID - verify that the frame at current location is valid (not overrun in the buffer).
+ *                     Returns file pointer if it is valid and -1 otherwise;
+ *  LSEEK_CIRC_READY - verify frame at current location is available (valid and acquired).
+ *                     Returns file pointer if it is ready or -1 otherwise
+ *  LSEEK_CIRC_WAIT -  sleep until next frame is acquired.
+ * All commands but (LSEEK_CIRC_TOWP, LSEEK_CIRC_LAST, LSEEK_CIRC_FIRST) will return -EINVAL if read
+ * pointer is not valid (i.e buffer was overrun and data pointed is lost). In case of success, they return
+ * current (byte *) to the start of the frame data (parameters are at offset - 32 from it).
+ * (0, SEEK_CUR) also verifies that the header is not overwritten. It can be used after buffering frame data to
+ * verify you got it all correctly.
+ *
+ * SEEK_CUR also supports the circular nature of the buffer and rolls over if needed.
+ *
+ * Additional commands for SEEK_END (they _DO_ modify the current file pointer):
+ *  LSEEK_CIRC_FREE -  returns remaining memory in circbuf from the current file pointer,
+ *                   or -EINVAL if the pointer is invalid. As this command uses the buffer write pointer
+ *                   that is updated only when the complete frame is in the buffer, the actual
+ *                   free memory may be less by a whole frame if compressor is running.
+ *  LSEEK_CIRC_USED - returns memory used in the in circbuf from the current file pointer,
+ *                   or -EINVAL if the pointer is invalid
+ *  @param[in]   file   pointer to \e file structure
+ *  @param[in]   offset offset inside buffer in bytes
+ *  @param[in]   orig   origin
+ *  @return      current file pointer position if operation was successful and error code otherwise
+ */
+loff_t circbuf_lseek(struct file *file, loff_t offset, int orig)
+{
+	unsigned int len32 = 0;
 	int inserted_bytes;
 	int last_image_chunk;
 	int img_start, next_img, padded_frame;
 	unsigned int minor = MINOR(file->f_inode->i_rdev);
-	unsigned int chn = minor_to_chn(minor);
- //  orig 0: position from begning
- //  orig 1: relative from current
- //  orig 2: position from last  address
-   int l = CCAM_DMA_SIZE;
-   int fl=0;// frame length
-   struct interframe_params_t * fp;
-   int fvld=-1;
-   int rp, bp; //, p;
-//   int pf; // previous frame
- dev_dbg(g_dev_ptr, "start processing LSEEK operation: offset = 0x%x, orig = 0x%x\n",(int) offset, (int) orig);
-   switch(orig) {
-   case SEEK_SET:
-     file->f_pos = offset;
-     break;
-   case SEEK_CUR:
-     if (offset) file->f_pos += offset;
-     else if (circbufValidPointer(file->f_pos, &fp, chn) <0 ) return -EINVAL; //!no frames at the specified location or pointer is not 32-byte aligned
-     break;
-   case SEEK_END:
-     if (offset <= 0) {
-        file->f_pos = l + offset;
-     } else { //! New functionality
-//!verify the frame pointer
-        switch (offset) {
-          case LSEEK_CIRC_TORP:
-              //file->f_pos=camSeqGetJPEG_rp()<<2; //! set file pointer to global read pointer, and proceed
-        	  file->f_pos = camseq_get_jpeg_rp(chn) << 2;
-          case LSEEK_CIRC_PREV:
-          case LSEEK_CIRC_NEXT:
-          case LSEEK_CIRC_SETP:
-          case LSEEK_CIRC_VALID:
-          case LSEEK_CIRC_READY:
-          case LSEEK_CIRC_FREE:
-          case LSEEK_CIRC_USED:
-        	  if ((fvld = circbufValidPointer(file->f_pos, &fp, chn)) < 0)
-        		  return -EINVAL; //!no frames at the specified location
-        }
-        switch (offset) {
-          case LSEEK_CIRC_FREE:
-        	  dev_dbg(g_dev_ptr, "LSEEK_CIRC_FREE: checking remaining memory in circbuf\n");
-        	  bp = file->f_pos - (camseq_get_jpeg_wp(chn) << 2);
-             return (file->f_pos = (bp > 0) ? bp : (bp + l)); //!Has a side effect of moving a file pointer!
-          case LSEEK_CIRC_USED:
-        	  dev_dbg(g_dev_ptr, "LSEEK_CIRC_USED: checking used memory in circbuf\n");
-        	  bp = (camseq_get_jpeg_wp(chn) << 2) - file->f_pos;
-             return (file->f_pos = (bp > 0) ? bp : (bp + l)); //!Has a side effect of moving a file pointer!
-          case LSEEK_CIRC_TORP:
-        	  // no actions to be done here, the pointer was set on previous step
-             break;
-          case LSEEK_CIRC_TOWP:
-             //file->f_pos=camSeqGetJPEG_wp()<<2; // no checking if it is valid
-        	  file->f_pos = camseq_get_jpeg_wp(chn) << 2;
-             break;
-          case LSEEK_CIRC_LAST:
-        	  next_img = camseq_get_jpeg_wp(chn) << 2;
-        	  //fvld = circbufValidPointer(next_img, &fp, chn);
-
-        	  dev_dbg(g_dev_ptr, "LSEEK_CIRC_LAST: next_img = 0x%x, fvld = %d\n", next_img, fvld);
-        	  dev_dbg(g_dev_ptr, "mem dump of last 0x40 bytes in buffer number %d\n", chn);
-        	  print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, &circbuf_priv[chn].buf_ptr[BYTE2DW(next_img - OFFSET_X40)], OFFSET_X40);
-
-        	  len32 = get_image_length(next_img, chn, &last_image_chunk);
-        	  if ((len32 & MARKER_FF) != MARKER_FF) {
-        		  // we should not be here as the position was checked in circbufValidPointer
-        		  dev_dbg(g_dev_ptr, "failed to get marker 0xFF at 0x%x, len32: 0x%x\n", next_img, len32);
-        		  return -EOVERFLOW;
-        	  }
-        	  len32 &= FRAME_LENGTH_MASK;
-        	  //inserted_bytes = ((CHUNK_SIZE - (((len32 % CHUNK_SIZE) + CCAM_MMAP_META) % CHUNK_SIZE) - ADJUSTMENT) % CHUNK_SIZE ) + ADJUSTMENT;
-        	  img_start = X393_BUFFSUB(last_image_chunk + CHUNK_SIZE - INSERTED_BYTES(len32) - CCAM_MMAP_META, len32);
-        	  dev_dbg(g_dev_ptr, "calculated start address = 0x%x, length = 0x%x\n", img_start, len32);
-        	  if (circbufValidPointer(img_start, &fp, chn) < 0)
-        		  return -EOVERFLOW;
-        	  file->f_pos = img_start;
-        	  dev_dbg(g_dev_ptr, "LSEEK_CIRC_LAST: moving file->f_pos to 0x%llx\n", file->f_pos);
-        	  break;
-          case LSEEK_CIRC_PREV:
-        	  next_img = camseq_get_jpeg_wp(chn) << 2;
-        	  fvld = circbufValidPointer(next_img, &fp, chn);
-
-        	  dev_dbg(g_dev_ptr, "LSEEK_CIRC_PREV: next_img = 0x%x, fvld = %d\n", next_img, fvld);
-        	  dev_dbg(g_dev_ptr, "mem dump of last 0x40 bytes in buffer number %d\n", chn);
-        	  print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, &circbuf_priv[chn].buf_ptr[BYTE2DW(next_img - OFFSET_X40)], OFFSET_X40);
-
-        	  len32 = get_image_length(next_img, chn, &last_image_chunk);
-        	  if ((len32 & MARKER_FF) != MARKER_FF) {
-        		  // we should not be here as the position was checked in circbufValidPointer
-        		  dev_dbg(g_dev_ptr, "failed to get marker 0xFF at 0x%x, len32: 0x%x\n", next_img, len32);
-        		  return -EOVERFLOW;
-        	  }
-        	  len32 &= 0xffffff;
-        	  inserted_bytes = ((CHUNK_SIZE - (((len32 % CHUNK_SIZE) + CCAM_MMAP_META) % CHUNK_SIZE) - ADJUSTMENT) % CHUNK_SIZE ) + ADJUSTMENT;
-        	  img_start = X393_BUFFSUB(last_image_chunk + CHUNK_SIZE - inserted_bytes - CCAM_MMAP_META, len32);
-        	  dev_dbg(g_dev_ptr, "LSEEK_CIRC_PREV: calculated start address = 0x%x, length = 0x%x\n", img_start, len32);
-
-        	  // move file pointer only if previous frame valid
-        	  len32 = get_image_length(img_start, chn, NULL);
-        	  if (circbufValidPointer(img_start, &fp, chn) < 0)
-        		  return -EOVERFLOW;
-        	  file->f_pos = img_start;
-        	  break;
-          case LSEEK_CIRC_NEXT:
- 	 	 	 dev_dbg(g_dev_ptr, "LSEEK_CIRC_NEXT: file->f_pos = 0x%x, fvld = %d, fp->len32 = 0x%x\n", file->f_pos, fvld, fp->frame_length);
-             if (fvld <= 0)
-                return -EOVERFLOW; //! no frames after current
-             // calculate the full length of current frame and advance file pointer by this value
-        	  padded_frame = fp->frame_length + INSERTED_BYTES(fp->frame_length) + CHUNK_SIZE + CCAM_MMAP_META;
-             file->f_pos = X393_BUFFADD(file->f_pos, padded_frame); // do it even if the next frame does not yet exist
-             dev_dbg(g_dev_ptr, "LSEEK_CIRC_NEXT: moving file->f_pos to 0x%x\n", file->f_pos);
-             break;
-          case LSEEK_CIRC_FIRST:
-          case LSEEK_CIRC_SCND:
-          {
-			   int nf = 0;   //! number of frames;
-			   int nz = 1; //! number of crossing of start of the circular buffer (counter to prevent looping forever)
-			   int prev_p, preprev_p;
-//! Starting from the write pointer do be able to count all the frames in the buffer
-             //rp=camSeqGetJPEG_wp();
-        	  rp = camseq_get_jpeg_wp(chn);
-             prev_p = preprev_p = rp;
-             file->f_pos = DW2BYTE(rp);
-             while (((fvld = circbufValidPointer(DW2BYTE(rp), &fp, chn)) >= 0) & (nz >= 0)) {
-               nf++;
-               preprev_p = prev_p; //! second known good (at least first one)
-               prev_p=rp;        //!now - current, known good
-               //fl=ccam_dma_buf[X313_BUFFSUB(rp, 9)] ^ X313_LENGTH_MASK;
-               len32 = get_image_length(DW2BYTE(rp), chn, last_image_chunk);
- 	 	 	   dev_dbg(g_dev_ptr, "LSEEK_CIRC_FIRST or LSEEK_CIRC_SCND: number of frames = %d, rp = 0x%x, fvld = %d, len32 = 0x%x", nf, rp, fvld, len32);
-               if ((len32 & MARKER_FF) != MARKER_FF ) break;  //! no frames before rp (==prev_p)
-//! move rp to the previous frame
-        	  len32 &= 0xffffff;
-        	  inserted_bytes = ((CHUNK_SIZE - (((len32 % CHUNK_SIZE) + CCAM_MMAP_META) % CHUNK_SIZE) - ADJUSTMENT) % CHUNK_SIZE ) + ADJUSTMENT;
-        	  img_start = X393_BUFFSUB(last_image_chunk + CHUNK_SIZE - inserted_bytes - CCAM_MMAP_META, len32);
-        	  dev_dbg(g_dev_ptr, "LSEEK_CIRC_FIRST or LSEEK_CIRC_SCND: calculated start address = 0x%x, length = 0x%x\n", img_start, len32);
-               rp = BYTE2DW(img_start);
-               if (rp > prev_p) nz-- ; // rolled through zero - make sure we'll not stuck in this loop forever
-             }
-             dev_dbg(g_dev_ptr, "LSEEK_CIRC_FIRST or LSEEK_CIRC_SCND: finish stepping back through frames, number of frames = %d, rp = 0x%x, fvld = %d, len32 = 0x%x", nf, rp, fvld, len32);
-             file->f_pos = ((offset == LSEEK_CIRC_SCND) ? preprev_p : prev_p) << 2;
-             break;
-          }
-          case LSEEK_CIRC_SETP:
-             //camSeqSetJPEG_rp(file->f_pos>>2);
-        	  dev_dbg(g_dev_ptr, "LSEK_CIRC_SETP: Setting jpeg_rp for channel %d to file->f_pos = 0x%x\n", chn, file->f_pos);
-        	  camseq_set_jpeg_rp(chn, file->f_pos >> 2);
-             break;
-          case LSEEK_CIRC_VALID:
-        	  // no actions to be done here, the pointer was checked on previous step
-        	  dev_dbg(g_dev_ptr, "LSEEK_CIRC_VALID: no action required\n");
-             break;
-          case LSEEK_CIRC_READY:
-        	  dev_dbg(g_dev_ptr, "LSEEK_CIRC_READY: checking fvld, fvld = %d\n", fvld);
-             if (fvld <=0) return -EINVAL; //! no frame is available better code?
-             break;
-          case LSEEK_CIRC_WAIT:
-        	  dev_dbg(g_dev_ptr, "LSEEK_CIRC_WAIT\n");
-              while (((fvld=circbufValidPointer(file->f_pos, &fp, chn)))==0) { //! only while not ready, ready or BAD - return
-                //wait_event_interruptible(circbuf_wait_queue,(camSeqGetJPEG_wp()<<2)!=file->f_pos);
-                wait_event_interruptible(circbuf_wait_queue, (camseq_get_jpeg_wp(chn) << 2) != file->f_pos);
-              }
-              if (fvld < 0) return -ESPIPE;      //!invalid seek - have better code?
-              return file->f_pos ; //! data already available, return file pointer
-          default:
-            if ((offset & ~0x1f)==LSEEK_DAEMON_CIRCBUF) {
-              wait_event_interruptible(circbuf_wait_queue, get_imageParamsThis(P_DAEMON_EN) & (1<<(offset & 0x1f)));
-            }
-        }
-        return ( file->f_pos ); //! file position >=0
-     }
-     break;
-   default:
-      return -EINVAL;
-   }
-   // roll-over position
-   while (file->f_pos < 0) file->f_pos+=l;
-   while (file->f_pos > l) file->f_pos-=l;
-   if ((orig !=SEEK_END) && (file->f_pos == l)) file->f_pos=0; //!only for lseek (fd,0,SEEK_END) the result will be file size, others will roll to 0
-   return  file->f_pos ;
+	unsigned int chn = minor_to_chn(minor, NULL);
+	struct interframe_params_t * fp;
+	int fvld = -1;
+	int rp, bp;
+	dev_dbg(g_dev_ptr, "start processing LSEEK operation: offset = 0x%x, orig = 0x%x\n",(int) offset, (int) orig);
+
+	switch (orig) {
+	case SEEK_SET:
+		file->f_pos = offset;
+		break;
+	case SEEK_CUR:
+		if (offset) file->f_pos += offset;
+		else if (circbuf_valid_ptr(file->f_pos, &fp, chn) < 0 ) return -EINVAL; //!no frames at the specified location or pointer is not 32-byte aligned
+		break;
+	case SEEK_END:
+		if (offset <= 0) {
+			file->f_pos = CCAM_DMA_SIZE + offset;
+		} else {
+			// verify current frame pointer
+			switch (offset) {
+			case LSEEK_CIRC_TORP:
+				file->f_pos = camseq_get_jpeg_rp(chn) << 2;
+			case LSEEK_CIRC_PREV:
+			case LSEEK_CIRC_NEXT:
+			case LSEEK_CIRC_SETP:
+			case LSEEK_CIRC_VALID:
+			case LSEEK_CIRC_READY:
+			case LSEEK_CIRC_FREE:
+			case LSEEK_CIRC_USED:
+				if ((fvld = circbuf_valid_ptr(file->f_pos, &fp, chn)) < 0)
+					return -EINVAL; // no frames at the specified location
+			}
+			switch (offset) {
+			case LSEEK_CIRC_FREE:
+				dev_dbg(g_dev_ptr, "LSEEK_CIRC_FREE: checking remaining memory in circbuf\n");
+				bp = file->f_pos - (camseq_get_jpeg_wp(chn) << 2);
+				return (file->f_pos = (bp > 0) ? bp : (bp + CCAM_DMA_SIZE)); //!Has a side effect of moving a file pointer!
+			case LSEEK_CIRC_USED:
+				dev_dbg(g_dev_ptr, "LSEEK_CIRC_USED: checking used memory in circbuf\n");
+				bp = (camseq_get_jpeg_wp(chn) << 2) - file->f_pos;
+				return (file->f_pos = (bp > 0) ? bp : (bp + CCAM_DMA_SIZE)); //!Has a side effect of moving a file pointer!
+			case LSEEK_CIRC_TORP:
+				// no actions to be done here, the pointer was set on previous step
+				break;
+			case LSEEK_CIRC_TOWP:
+				file->f_pos = camseq_get_jpeg_wp(chn) << 2;
+				break;
+			case LSEEK_CIRC_LAST:
+				next_img = camseq_get_jpeg_wp(chn) << 2;
+
+				dev_dbg(g_dev_ptr, "LSEEK_CIRC_LAST: next_img = 0x%x, fvld = %d\n", next_img, fvld);
+				dev_dbg(g_dev_ptr, "mem dump of last 0x40 bytes in buffer number %d\n", chn);
+				print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, &circbuf_priv[chn].buf_ptr[BYTE2DW(next_img - OFFSET_X40)], OFFSET_X40);
+
+				len32 = get_image_length(next_img, chn, &last_image_chunk);
+				if ((len32 & MARKER_FF) != MARKER_FF) {
+					// we should not be here as the position was checked in circbufValidPointer
+					dev_dbg(g_dev_ptr, "failed to get marker 0xFF at 0x%x, len32: 0x%x\n", next_img, len32);
+					return -EOVERFLOW;
+				}
+				len32 &= FRAME_LENGTH_MASK;
+				img_start = X393_BUFFSUB(last_image_chunk + CHUNK_SIZE - INSERTED_BYTES(len32) - CCAM_MMAP_META, len32);
+				dev_dbg(g_dev_ptr, "calculated start address = 0x%x, length = 0x%x\n", img_start, len32);
+				if (circbuf_valid_ptr(img_start, &fp, chn) < 0)
+					return -EOVERFLOW;
+				file->f_pos = img_start;
+				dev_dbg(g_dev_ptr, "LSEEK_CIRC_LAST: moving file->f_pos to 0x%llx\n", file->f_pos);
+				break;
+			case LSEEK_CIRC_PREV:
+				next_img = camseq_get_jpeg_wp(chn) << 2;
+				fvld = circbuf_valid_ptr(next_img, &fp, chn);
+
+				dev_dbg(g_dev_ptr, "LSEEK_CIRC_PREV: next_img = 0x%x, fvld = %d\n", next_img, fvld);
+				dev_dbg(g_dev_ptr, "mem dump of last 0x40 bytes in buffer number %d\n", chn);
+				print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, &circbuf_priv[chn].buf_ptr[BYTE2DW(next_img - OFFSET_X40)], OFFSET_X40);
+
+				len32 = get_image_length(next_img, chn, &last_image_chunk);
+				if ((len32 & MARKER_FF) != MARKER_FF) {
+					// we should not be here as the position was checked in circbufValidPointer
+					dev_dbg(g_dev_ptr, "failed to get marker 0xFF at 0x%x, len32: 0x%x\n", next_img, len32);
+					return -EOVERFLOW;
+				}
+				len32 &= 0xffffff;
+				inserted_bytes = ((CHUNK_SIZE - (((len32 % CHUNK_SIZE) + CCAM_MMAP_META) % CHUNK_SIZE) - ADJUSTMENT) % CHUNK_SIZE ) + ADJUSTMENT;
+				img_start = X393_BUFFSUB(last_image_chunk + CHUNK_SIZE - inserted_bytes - CCAM_MMAP_META, len32);
+				dev_dbg(g_dev_ptr, "LSEEK_CIRC_PREV: calculated start address = 0x%x, length = 0x%x\n", img_start, len32);
+
+				// move file pointer only if previous frame valid
+				len32 = get_image_length(img_start, chn, NULL);
+				if (circbuf_valid_ptr(img_start, &fp, chn) < 0)
+					return -EOVERFLOW;
+				file->f_pos = img_start;
+				break;
+			case LSEEK_CIRC_NEXT:
+				dev_dbg(g_dev_ptr, "LSEEK_CIRC_NEXT: file->f_pos = 0x%x, fvld = %d, fp->len32 = 0x%x\n", file->f_pos, fvld, fp->frame_length);
+				if (fvld <= 0)
+					return -EOVERFLOW; //! no frames after current
+				// calculate the full length of current frame and advance file pointer by this value
+				padded_frame = fp->frame_length + INSERTED_BYTES(fp->frame_length) + CHUNK_SIZE + CCAM_MMAP_META;
+				file->f_pos = X393_BUFFADD(file->f_pos, padded_frame); // do it even if the next frame does not yet exist
+				dev_dbg(g_dev_ptr, "LSEEK_CIRC_NEXT: moving file->f_pos to 0x%x\n", file->f_pos);
+				break;
+			case LSEEK_CIRC_FIRST:
+			case LSEEK_CIRC_SCND:
+			{
+				int nf = 0; // number of frames;
+				int nz = 1; // number of start crossing of the circular buffer (counter to prevent looping forever)
+				int prev_p, preprev_p;
+				// starting from the write pointer to be able to count all the frames in the buffer
+				rp = camseq_get_jpeg_wp(chn);
+				prev_p = preprev_p = rp;
+				file->f_pos = DW2BYTE(rp);
+				while (((fvld = circbuf_valid_ptr(DW2BYTE(rp), &fp, chn)) >= 0) & (nz >= 0)) {
+					nf++;
+					preprev_p = prev_p; // second known good (at least first one)
+					prev_p=rp;          // now - current, known good
+					len32 = get_image_length(DW2BYTE(rp), chn, last_image_chunk);
+					dev_dbg(g_dev_ptr, "LSEEK_CIRC_FIRST or LSEEK_CIRC_SCND: number of frames = %d, rp = 0x%x, fvld = %d, len32 = 0x%x", nf, rp, fvld, len32);
+					if ((len32 & MARKER_FF) != MARKER_FF ) break;  //! no frames before rp (==prev_p)
+					//! move rp to the previous frame
+					len32 &= 0xffffff;
+					inserted_bytes = ((CHUNK_SIZE - (((len32 % CHUNK_SIZE) + CCAM_MMAP_META) % CHUNK_SIZE) - ADJUSTMENT) % CHUNK_SIZE ) + ADJUSTMENT;
+					img_start = X393_BUFFSUB(last_image_chunk + CHUNK_SIZE - inserted_bytes - CCAM_MMAP_META, len32);
+					dev_dbg(g_dev_ptr, "LSEEK_CIRC_FIRST or LSEEK_CIRC_SCND: calculated start address = 0x%x, length = 0x%x\n", img_start, len32);
+					rp = BYTE2DW(img_start);
+					if (rp > prev_p) nz-- ; // rolled through zero - make sure we'll not stuck in this loop forever
+				}
+				dev_dbg(g_dev_ptr, "LSEEK_CIRC_FIRST or LSEEK_CIRC_SCND: finish stepping back through frames, number of frames = %d, rp = 0x%x, fvld = %d, len32 = 0x%x", nf, rp, fvld, len32);
+				file->f_pos = ((offset == LSEEK_CIRC_SCND) ? preprev_p : prev_p) << 2;
+				break;
+			}
+			case LSEEK_CIRC_SETP:
+				dev_dbg(g_dev_ptr, "LSEK_CIRC_SETP: Setting jpeg_rp for channel %d to file->f_pos = 0x%x\n", chn, file->f_pos);
+				camseq_set_jpeg_rp(chn, file->f_pos >> 2);
+				break;
+			case LSEEK_CIRC_VALID:
+				// no actions to be done here, the pointer was checked on previous step
+				dev_dbg(g_dev_ptr, "LSEEK_CIRC_VALID: no action required\n");
+				break;
+			case LSEEK_CIRC_READY:
+				dev_dbg(g_dev_ptr, "LSEEK_CIRC_READY: checking fvld, fvld = %d\n", fvld);
+				if (fvld <=0) return -EINVAL; // no frame is available better code?
+				break;
+			case LSEEK_CIRC_WAIT:
+				dev_dbg(g_dev_ptr, "LSEEK_CIRC_WAIT\n");
+				while (((fvld=circbuf_valid_ptr(file->f_pos, &fp, chn)))==0) { // only while not ready, ready or BAD - return
+					wait_event_interruptible(circbuf_wait_queue, (camseq_get_jpeg_wp(chn) << 2) != file->f_pos);
+				}
+				if (fvld < 0) return -ESPIPE;      // invalid seek - have better code?
+				return file->f_pos ; // data already available, return file pointer
+			default:
+				if ((offset & ~0x1f)==LSEEK_DAEMON_CIRCBUF) {
+					wait_event_interruptible(circbuf_wait_queue, get_imageParamsThis(P_DAEMON_EN) & (1<<(offset & 0x1f)));
+				}
+			}
+			return ( file->f_pos ); // file position >= 0
+		}
+		break;
+	default:
+		return -EINVAL;
+	}
+	// roll-over position
+	while (file->f_pos < 0) file->f_pos += CCAM_DMA_SIZE;
+	while (file->f_pos > CCAM_DMA_SIZE) file->f_pos -= CCAM_DMA_SIZE;
+	if ((orig !=SEEK_END) && (file->f_pos == CCAM_DMA_SIZE)) file->f_pos=0; // only for lseek(fd,0,SEEK_END) the result will be file size, others will roll to 0
+	return  file->f_pos ;
 }
 
 /**
- * @brief This function handles write operations for circbuf file
+ * @brief This function handles write operations for circbuf files.
+ * Note: never use \e file->f_pos in this function.
  * @param[in]   file  pointer to <em>struct file</em>
  * @param[in]   buf   pointer to buffer containing data
  * @param[in]   count number of bytes in buffer
  * @param[in]   off   offset
  * @return      number of bytes read form \e buf
  */
-ssize_t circbuf_write(struct file * file, const char * buf, size_t count, loff_t *off) {
+ssize_t circbuf_write(struct file *file, const char *buf, size_t count, loff_t *off)
+{
 	unsigned long p;
-	char *char_pb = (char *)ccam_dma_buf;
-	struct circbuf_pd *priv = file->private_data;
+	unsigned int minor = MINOR(file->f_inode->i_rdev);
+	unsigned int chn = minor_to_chn(minor, NULL);
+	dev_dbg(g_dev_ptr, "minor = 0x%x, count = 0x%x, off = 0x%x", minor, count, off);
 
 	/* debug code follows*/
 	switch (buf[0] - 0x30) {
@@ -607,16 +605,13 @@ ssize_t circbuf_write(struct file * file, const char * buf, size_t count, loff_t
 	}
 	/* debug code end */
 
-	//D(printk("circbuf_write\n"));
-	/// ************* NOTE: Never use file->f_pos in write() and read() !!!
 	p = *off;
-	if(p >= (CCAM_DMA_SIZE << 2))
-		p = (CCAM_DMA_SIZE << 2);
-	if((p + count) > (CCAM_DMA_SIZE << 2)) { // truncate count
-		count = (CCAM_DMA_SIZE << 2) - p;
-	}
-	if(count) {
-		if(copy_from_user(&char_pb[p], buf, count))
+	if (p >= CCAM_DMA_SIZE)
+		p = CCAM_DMA_SIZE;
+	if ((p + count) > CCAM_DMA_SIZE)
+		count = CCAM_DMA_SIZE - p;
+	if (count) {
+		if (copy_from_user(&circbuf_priv[chn].buf_ptr[BYTE2DW(p)], buf, count))
 			return -EFAULT;
 		*off += count;
 	}
@@ -624,36 +619,39 @@ ssize_t circbuf_write(struct file * file, const char * buf, size_t count, loff_t
 }
 
 /**
- * @brief This function handles read operations for circbuf file
+ * @brief This function handles read operations for circbuf files.
+ * Note: never use \e file->f_pos in this function.
  * @param[in]   file  pointer to <em>struct file</em>
  * @param[in]   buf   pointer to buffer where data will be written to
  * @param[in]   count number of bytes written to \e buf
  * @param[in]   off   offset
  * @return      number of bytes written to \e buf
  */
-ssize_t circbuf_read(struct file * file, char * buf, size_t count, loff_t *off) {
-  unsigned long p;
-  char * char_pb = (char *) ccam_dma_buf;
-  struct circbuf_pd *priv = file->private_data;
-
-  p = *off;
-  dev_dbg(g_dev_ptr, "read from circbuf pos = %d, count = %d, off = %d\n", p, count, off);
-  if (p >= (CCAM_DMA_SIZE<<2))  p = (CCAM_DMA_SIZE<<2);
-  if( (p + count) > (CCAM_DMA_SIZE<<2)) { // truncate count
-    count = (CCAM_DMA_SIZE<<2) - p;
-  }
-  if (count) {
-    if (copy_to_user(buf, &char_pb[p], count)) return -EFAULT;
-//    file->f_pos+=count;
-    *off+=count;
-  }
-  return count;
+ssize_t circbuf_read(struct file *file, char *buf, size_t count, loff_t *off)
+{
+	unsigned long p;
+	unsigned int minor = MINOR(file->f_inode->i_rdev);
+	unsigned int chn = minor_to_chn(minor, NULL);
+	dev_dbg(g_dev_ptr, "minor = 0x%x, count = 0x%x, off = 0x%x", minor, count, off);
+
+	p = *off;
+	if (p >= CCAM_DMA_SIZE)
+		p = CCAM_DMA_SIZE;
+	if ((p + count) > CCAM_DMA_SIZE)
+		count = CCAM_DMA_SIZE - p;
+	if (count) {
+		if (copy_to_user(buf, &circbuf_priv[chn].buf_ptr[BYTE2DW(p)], count))
+			return -EFAULT;
+		*off+=count;
+	}
+	return count;
 }
 
 int circbuf_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	int ret;
-	int chn = minor_to_chn(MINOR(file->f_inode->i_rdev));
+	unsigned int minor = MINOR(file->f_inode->i_rdev);
+	unsigned int chn = minor_to_chn(minor, NULL);
 
 	dev_dbg(g_dev_ptr, "vm_start = 0x%lx\n", vma->vm_start);
 	dev_dbg(g_dev_ptr, "vm_end = 0x%lx\n", vma->vm_end);
@@ -661,10 +659,9 @@ int circbuf_mmap(struct file *file, struct vm_area_struct *vma)
 	dev_dbg(g_dev_ptr, "vm_file = 0x%lx\n", (unsigned long)vma->vm_file);
 	dev_dbg(g_dev_ptr, "ccam_dma_buf = 0x%lx\n", (unsigned long)circbuf_priv[chn].phys_addr);
 
-	/* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
+	/* remap_pfn_range will mark the range VM_IO and VM_RESERVED */
 	ret = remap_pfn_range(vma,
 			vma->vm_start,
-			//((unsigned long) virt_to_phys(&ccam_dma_buf[0])) >> PAGE_SHIFT, // Should be page-aligned
 			circbuf_priv[chn].phys_addr >> PAGE_SHIFT,
 			vma->vm_end - vma->vm_start,
 			vma->vm_page_prot);
@@ -674,34 +671,41 @@ int circbuf_mmap(struct file *file, struct vm_area_struct *vma)
 
 	return 0;
 }
-/*!===========================================================================
- *! If the current read pointer is invalid, circbuf_poll returns POLLHUP
- *! as no data will be ever available until file poinetr is reset.
- *! if it is valid, wait is setup and the blocking condition occurs 
- *! ifthe current file pointer is equal to the FPGA write pointer
- *!===========================================================================*/
+
+/**
+ * @brief This driver method is called when user-space program performs <em>poll, select</em> or
+ * \e epoll system call.
+ *
+ * If the current read pointer is invalid, circbuf_poll returns POLLHUP
+ * as no data will be ever available until file pointer is reset.
+ * If it is valid, wait is setup and blocking condition occurs in case
+ * current file pointer is equal to the FPGA write pointer.
+ * @param[in]   file   pointer to <em>struct file</em> structure
+ * @param[in]   wait   pointer to <em>struct poll_table</em> structure
+ * return       POLLHUP if pointer is invalid, (POLLIN | POLLRDNORM) if frame is ready,
+ *              0 in case nothing is ready.
+ */
 unsigned int circbuf_poll (struct file *file, poll_table *wait)
 {
 	int w_ptr;
 	unsigned int minor = MINOR(file->f_inode->i_rdev);
-	unsigned int chn = minor_to_chn(minor);
-
+	unsigned int chn = minor_to_chn(minor, NULL);
 	struct interframe_params_t * fp;
-	struct circbuf_pd * privData;
-	privData = (struct circbuf_pd *) file->private_data;
-	int rslt; //!result of testing read poinetr
+	int rslt;
 	dev_dbg(g_dev_ptr, "minor = 0x%x\n", minor);
-	rslt= circbufValidPointer(file->f_pos, &fp, chn);
-	if        (rslt < 0) { //! not a valid read pointer, probable buffer overrun
+
+	rslt = circbuf_valid_ptr(file->f_pos, &fp, chn);
+	if (rslt < 0) {
+		// not a valid read pointer, probable buffer overrun
 		dev_dbg(g_dev_ptr, "invalid pointer file->f_pos = 0x%x\n", file->f_pos);
 		return  POLLHUP ;
 	} else if (rslt > 0) {
 		return POLLIN | POLLRDNORM; //! there was frame already available
-	} else { //! pointer valid, no frame yet
+	} else {
+		// pointer valid, no frame yet
 		poll_wait(file, &circbuf_wait_queue, wait);
-		//! Frame might become available during call to poll_wait so nobody will wake us up.
-		//! Let's see if there is stillno frame
-		//if ((camSeqGetJPEG_wp()<<2)!=file->f_pos) return POLLIN | POLLRDNORM; //! we are lucky - got it
+		// Frame might become available during call to poll_wait so nobody will wake us up,
+		// let's see if there is still no frame.
 		w_ptr = camseq_get_jpeg_wp(chn) << 2;
 		if (w_ptr != file->f_pos)
 			return POLLIN | POLLRDNORM; //! we are lucky - got it

src/include/elphel/driver_numbers.h

@@ -27,12 +27,23 @@
 #define IMAGERAW_MINOR_FPN	2
 #define IMAGERAW_MINOR_UNLOCK	3
 
-#define CIRCBUF_MINOR_CHN_OFFSET 30
-#define CIRCBUF_MINOR_CHN_0      30
-#define CIRCBUF_MINOR_CHN_1      31
-#define CIRCBUF_MINOR_CHN_2      32
-#define CIRCBUF_MINOR_CHN_3      33
+#define CIRCBUF_MINOR             0x20
+#define CIRCBUF_MINOR_CHN_0       0x20
+#define CIRCBUF_MINOR_CHN_1       0x21
+#define CIRCBUF_MINOR_CHN_2       0x22
+#define CIRCBUF_MINOR_CHN_3       0x23
 
+#define JPEGHEAD_MINOR            0x30
+#define JPEGHEAD_MINOR_CHN_0      0x30
+#define JPEGHEAD_MINOR_CHN_1      0x31
+#define JPEGHEAD_MINOR_CHN_2      0x32
+#define JPEGHEAD_MINOR_CHN_3      0x33
+
+#define HUFFMAN_MINOR             0x40
+#define HUFFMAN_MINOR_CHN_0       0x40
+#define HUFFMAN_MINOR_CHN_1       0x41
+#define HUFFMAN_MINOR_CHN_2       0x42
+#define HUFFMAN_MINOR_CHN_3       0x43
 
 #define CMOSCAM_MINOR_RWTABLES    9
 #define CMOSCAM_MINOR_CIRCBUF    11