linux-kernel - [PATCH v9 03/11] dmaengine: dw: set polarity of handshake interface

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Date:	Mon, 20 Jun 2016 12:17:54 +0300
From:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:	Bryan O'Donoghue <pure.logic@...us-software.ie>,
	Peter Hurley <peter@...leysoftware.com>,
	linux-serial@...r.kernel.org, Vinod Koul <vinod.koul@...el.com>,
	linux-kernel@...r.kernel.org, dmaengine@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	ismo.puustinen@...el.com,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [PATCH v9 03/11] 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@...el.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 drivers/dma/dw/core.c                | 4 ++++
 include/linux/platform_data/dma-dw.h | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
index 81b06df..59f571c 100644
--- a/drivers/dma/dw/core.c
+++ b/drivers/dma/dw/core.c
@@ -150,6 +150,10 @@ 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 |= dwc->dws.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
--- 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;
 };
 
 /**
-- 
2.8.1