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 81b06dfd7e06fceff3fa0c883157ca58c0dd63cd..80e74216cd5630d1093a61ddada5b9d7e6ddfe05 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 d15d8ba8cc240c7b846936692b604c0e2488f177..4636c933530516ac6e089c18ada62009bc849c3e 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;
 };
 
 /**