dmaengine: dw: set polarity of handshake interface

Intel Quark UART uses DesignWare DMA IP. Though the DMA IP is connected in such
way that handshake interface uses inverted polarity. We have to provide a
possibility to set this in the DMA driver when configuring a channel.

Introduce a new member of custom slave configuration called 'hs_polarity' and
set active low polarity in case this value is 'true'.

Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
index 81b06df..80e7421 100644 (file)
--- a/drivers/dma/dw/core.c
+++ b/drivers/dma/dw/core.c
@@ -143,6 +143,7 @@ static void dwc_initialize(struct dw_dma_chan *dwc)
        struct dw_dma *dw = to_dw_dma(dwc->chan.device);
        u32 cfghi = DWC_CFGH_FIFO_MODE;
        u32 cfglo = DWC_CFGL_CH_PRIOR(dwc->priority);
+       bool hs_polarity = dwc->dws.hs_polarity;
 
        if (test_bit(DW_DMA_IS_INITIALIZED, &dwc->flags))
                return;
@@ -150,6 +151,9 @@ static void dwc_initialize(struct dw_dma_chan *dwc)
        cfghi |= DWC_CFGH_DST_PER(dwc->dws.dst_id);
        cfghi |= DWC_CFGH_SRC_PER(dwc->dws.src_id);
 
+       /* Set polarity of handshake interface */
+       cfglo |= hs_polarity ? DWC_CFGL_HS_DST_POL | DWC_CFGL_HS_SRC_POL : 0;
+
        channel_writel(dwc, CFG_LO, cfglo);
        channel_writel(dwc, CFG_HI, cfghi);
 

diff --git a/include/linux/platform_data/dma-dw.h b/include/linux/platform_data/dma-dw.h
index d15d8ba..4636c93 100644 (file)
--- a/include/linux/platform_data/dma-dw.h
+++ b/include/linux/platform_data/dma-dw.h
@@ -23,6 +23,7 @@
  * @dst_id:    dst request line
  * @m_master:  memory master for transfers on allocated channel
  * @p_master:  peripheral master for transfers on allocated channel
+ * @hs_polarity:set active low polarity of handshake interface
  */
 struct dw_dma_slave {
        struct device           *dma_dev;
@@ -30,6 +31,7 @@ struct dw_dma_slave {
        u8                      dst_id;
        u8                      m_master;
        u8                      p_master;
+       bool                    hs_polarity;
 };
 
 /**