this feature has been supported in kernel 3.9-rc5,  this contain the following patches. Please evalutate if it can be backported to raring kernel.

1. commit b801479bb6f5b66f5a35feaa72451ac5ac152ef5
    Author: Heikki Krogerus <email address hidden>
    Date:   Thu Oct 18 17:34:08 2012 +0300

    dmaengine: dw_dmac: amend description and indentation

2. commit 21d43f49cb5e132e74bde9e34ac0760f79ab85a9
   Author: Andy Shevchenko <email address hidden>
   Date:   Thu Oct 18 17:34:09 2012 +0300

   dw_dmac: change dev_printk() to corresponding macros

3.commit 6168d5670bd764557b5e06b1842964a44cf34a45
   Author: Andy Shevchenko <email address hidden>
   Date:   Thu Oct 18 17:34:10 2012 +0300

    dw_dmac: don't call platform_get_drvdata twice

4. commit ba84bd7146b9244de0ce04cdc668521a73f5336f
   Author: Andy Shevchenko <email address hidden>
   Date:   Thu Oct 18 17:34:11 2012 +0300

    dw_dmac: change dev_crit to dev_WARN in dwc_handle_error

5. commit e63a47a361e03eaf79e0f2f6cdaca8e7679d1867
    Author: Andy Shevchenko <email address hidden>
    Date:   Thu Oct 18 17:34:12 2012 +0300

    dw_dmac: introduce to_dw_desc() macro

6. commit 123de543414bce42da9729071962d4a9512612c8
   Author: Andy Shevchenko <email address hidden>
    Date:   Wed Jan 9 10:17:01 2013 +0200

    dw_dmac: absence of pdata isn't critical when autocfg is set

7. commit cbd65312ba6b508e994d40729e84a51301870bcc
    Author: Andy Shevchenko <email address hidden>
    Date:   Wed Jan 9 10:17:11 2013 +0200

    dw_dmac: check for mapping errors

8. commit 21e93c1e7dae0e8b1914a522c331f0f7763fa89d
    Author: Andy Shevchenko <email address hidden>
    Date:   Wed Jan 9 10:17:12 2013 +0200

    dw_dmac: remove redundant check

9. commit f5c6a7df35b04db906577e90fa5e133e56433bcf
    Author: Andy Shevchenko <email address hidden>
   Date:   Wed Jan 9 10:17:13 2013 +0200

   dw_dmac: update tx_node_active in dwc_do_single_block

10. commit 21fe3c5245647d200a7ba25d42b80d21c578a8dc
      Author: Andy Shevchenko <email address hidden>
      Date:   Wed Jan 9 10:17:14 2013 +0200

    dma: dw_dmac: add dwc_chan_pause and dwc_chan_resume

11. commit 61cc13a51bcff737ce02d2047834171c0365b00d
      Author: Andy Shevchenko <email address hidden>
      Date:   Thu Jan 10 10:52:56 2013 +0200

    dmaengine: introduce is_slave_direction function

12. commit 782bc950d84e404422ba21008fd51ee894c8d231
      Author: Sascha Hauer <email address hidden>
      Date:   Thu Sep 30 13:56:32 2010 +0000

    dmaengine: add possibility for cyclic transfers

13. commit f44b92f4dd2f6caf326b149e0b9636a1d4e50184
     Author: Andy Shevchenko <email address hidden>
     Date:   Thu Jan 10 10:52:58 2013 +0200

    dma: dw_dmac: check direction properly in dw_dma_cyclic_prep

14. commit 0efcdb20f4a83967c99da3d3bef9018f86532fae
     Author: Andy Shevchenko <email address hidden>
     Date:   Thu Jan 10 10:52:59 2013 +0200

    dma: ep93xx_dma: reuse is_slave_direction helper

15. commit 5127c4f8a314b798459985d93f7829cf9cf9bbc3
     Author: Andy Shevchenko <email address hidden>
     Date:   Thu Jan 10 10:53:00 2013 +0200

    dma: ipu_idmac: reuse is_slave_direction helper

16. commit a725dcc0342b4d9ffc6ae4aedc2973d902aabeb1
     Author: Andy Shevchenko <email address hidden>
     Date:   Thu Jan 10 10:53:01 2013 +0200

    dma: ste_dma40: reuse is_slave_direction helper

17. commit 01126856ff4f7d4cc5899c208fd4d3c7d0a2b83a
    Author: Andy Shevchenko <email address hidden>
    Date:   Thu Jan 10 10:53:02 2013 +0200

    dw_dmac: call .probe after we have a device in place

18. commit 0fdb567fc72da906e230ce7e2aae2feba260a6be
      Author: Andy Shevchenko <email address hidden>
     Date:   Thu Jan 10 10:53:03 2013 +0200

    dw_dmac: store direction in the custom channel structure

19. commit 495aea4b571d1b7f77883f87754247b115627f68
     Author: Andy Shevchenko <email address hidden>
     Date:   Thu Jan 10 11:11:41 2013 +0200

    dw_dmac: make usage of dw_dma_slave optional

20. commit 23d5f4ec9de43dbc73a42f1483d9339b907c3dff
      Author: Andy Shevchenko <email address hidden>
      Date:   Thu Jan 10 10:53:05 2013 +0200

    dw_dmac: backlink to dw_dma in dw_dma_chan is superfluous

21. commit f8122a82d2eae8ef42de48829deed0ca9d9e1f17
     Author: Andy Shevchenko <email address hidden>
     Date:   Wed Jan 16 15:48:50 2013 +0200

    dw_dmac: allocate dma descriptors from DMA_COHERENT memory

22. commit 5be10f349bc0a2f3dd2ab6417ffe29746403984c
     Author: Andy Shevchenko <email address hidden>
     Date:   Thu Jan 17 10:03:01 2013 +0200

    dw_dmac: don't exceed AHB master number in dwc_get_data_width

23. commit 77bcc497c60ec62dbb84abc809a6e218d53409e9
     Author: Andy Shevchenko <email address hidden>
     Date:   Fri Jan 18 14:14:15 2013 +0200

    dw_dmac: move soft LLP code from tasklet to dwc_scan_descriptors

24. commit 985a6c7dcf309378b91d16cdbdb0909479f99c33
     Author: Andy Shevchenko <email address hidden>
     Date:   Fri Jan 18 17:10:59 2013 +0200

    dw_dmac: print out DW_PARAMS and DWC_PARAMS when debug

25. commit fdf475fa40f1468cf43a72b270f74dc6a4a5c905
     Author: Andy Shevchenko <email address hidden>
     Date:   Fri Jan 25 11:48:00 2013 +0200

    dw_dmac: remove unnecessary tx_list field in dw_dma_chan

26. commit 30d38a3286b140ae8cea84a93cde1f112e352aaf
     Author: Andy Shevchenko <email address hidden>
     Date:   Fri Jan 25 11:48:01 2013 +0200

    dw_dmac: introduce total_len field in struct dw_desc

27. commit 176dcec50f3f0bc46f11b983c1a3bbc2dd3514fd
     Author: Andy Shevchenko <email address hidden>
     Date:   Fri Jan 25 11:48:02 2013 +0200

    dw_dmac: fill individual length of descriptor

28. commit 4702d5244ca947263e8b7eb2ba6d8721e80c46e2
     Author: Andy Shevchenko <email address hidden>
     Date:   Fri Jan 25 11:48:03 2013 +0200

    dw_dmac: return proper residue value

29. commit 877e86f28385407f05c5aa4e397d4ccb3233f01a
     Author: Andy Shevchenko <email address hidden>
    Date:   Thu Feb 14 10:41:09 2013 +0200

    dw_dmac: apply default dma_mask if needed

30. commit cfdf5b6cc5985014a7ce891093f4fd0ae2d27ca6
     Author: Mika Westerberg <email address hidden>
     Date:   Thu Feb 7 17:36:28 2013 +0200

    dw_dmac: add support for Lynxpoint DMA controllers

31. commit bce95c63ef1bcf528ea45c41505eb4c21560d92d
    Author: Andy Shevchenko <email address hidden>
    Date:   Wed Feb 20 13:52:17 2013 +0200

    dw_dmac: adjust slave_id accordingly to request line base