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 'polarity' and set
active low polarity in case this value is 'true'.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
drivers/dma/dw/core.c | 2 ++
include/linux/platform_data/dma-dw.h | 2 ++
2 files changed, 4 insertions(+)
diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
index 81b06df..9c7bc7a 100644
--- a/drivers/dma/dw/core.c
+++ b/drivers/dma/dw/core.c
@@ -150,6 +150,8 @@ 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);
+ cfglo |= dwc->dws.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..192f3a2 100644
--- 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
+ * @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 polarity;
};
/**
--
2.8.0.rc3
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