linux-kernel - [PATCH 3/5] dmaengine: qca: bam

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Message-Id: <1481795755-15302-4-git-send-email-absahu@codeaurora.org>
Date:   Thu, 15 Dec 2016 15:25:53 +0530
From:   Abhishek Sahu <absahu@...eaurora.org>
To:     vinod.koul@...el.com, dan.j.williams@...el.com,
        andy.gross@...aro.org
Cc:     stanimir.varbanov@...aro.org, mcgrof@...e.com,
        okaya@...eaurora.org, pramod.gurav@...aro.org, arnd@...db.de,
        linux-kernel@...r.kernel.org, dmaengine@...r.kernel.org,
        linux-arm-msm@...r.kernel.org,
        Abhishek Sahu <absahu@...eaurora.org>
Subject: [PATCH 3/5] dmaengine: qca: bam_dma: Add support for bam sgl

The default SG does not have flag field but the BAM requires
flags to be passed for each SG. Since SG is linux generic and
other subsystem drivers also use this SG, so we cannot add flag
field in default SG. Now, this patch adds BAM SG and its mapping
operations. This BAM SG contains generic SG and DMA flag field.
The mapping operations are just wrapper functions
over generic SG functions with per-SG DMA flag support.

Signed-off-by: Abhishek Sahu <absahu@...eaurora.org>
---
 include/linux/dma/qcom_bam_dma.h | 78 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)

diff --git a/include/linux/dma/qcom_bam_dma.h b/include/linux/dma/qcom_bam_dma.h
index c3b68c2..2307c4d 100644
--- a/include/linux/dma/qcom_bam_dma.h
+++ b/include/linux/dma/qcom_bam_dma.h
@@ -17,9 +17,87 @@
 #ifndef _QCOM_BAM_DMA_H
 #define _QCOM_BAM_DMA_H
 
+#include <linux/dma-mapping.h>
+
 #define DESC_FLAG_INT BIT(15)
 #define DESC_FLAG_EOT BIT(14)
 #define DESC_FLAG_EOB BIT(13)
 #define DESC_FLAG_NWD BIT(12)
 
+/*
+ * QCOM BAM DMA SGL struct
+ *
+ * @sgl: DMA SGL
+ * @dma_flags: BAM DMA flags
+ */
+struct qcom_bam_sgl {
+	struct scatterlist sgl;
+	unsigned int dma_flags;
+};
+
+/*
+ * qcom_bam_sg_init_table - Init QCOM BAM SGL
+ * @bam_sgl: bam sgl
+ * @nents: number of entries in bam sgl
+ *
+ * This function performs the initialization for each SGL in BAM SGL
+ * with generic SGL API.
+ */
+static inline void qcom_bam_sg_init_table(struct qcom_bam_sgl *bam_sgl,
+		unsigned int nents)
+{
+	int i;
+
+	for (i = 0; i < nents; i++)
+		sg_init_table(&bam_sgl[i].sgl, 1);
+}
+
+/*
+ * qcom_bam_unmap_sg - Unmap QCOM BAM SGL
+ * @dev: device for which unmapping needs to be done
+ * @bam_sgl: bam sgl
+ * @nents: number of entries in bam sgl
+ * @dir: dma transfer direction
+ *
+ * This function performs the DMA unmapping for each SGL in BAM SGL
+ * with generic SGL API.
+ */
+static inline void qcom_bam_unmap_sg(struct device *dev,
+	struct qcom_bam_sgl *bam_sgl, int nents, enum dma_data_direction dir)
+{
+	int i;
+
+	for (i = 0; i < nents; i++)
+		dma_unmap_sg(dev, &bam_sgl[i].sgl, 1, dir);
+}
+
+/*
+ * qcom_bam_map_sg - Map QCOM BAM SGL
+ * @dev: device for which mapping needs to be done
+ * @bam_sgl: bam sgl
+ * @nents: number of entries in bam sgl
+ * @dir: dma transfer direction
+ *
+ * This function performs the DMA mapping for each SGL in BAM SGL
+ * with generic SGL API.
+ *
+ * returns 0 on error and > 0 on success
+ */
+static inline int qcom_bam_map_sg(struct device *dev,
+	struct qcom_bam_sgl *bam_sgl, int nents, enum dma_data_direction dir)
+{
+	int i, ret = 0;
+
+	for (i = 0; i < nents; i++) {
+		ret = dma_map_sg(dev, &bam_sgl[i].sgl, 1, dir);
+		if (!ret)
+			break;
+	}
+
+	/* unmap the mapped sgl from previous loop in case of error */
+	if (!ret)
+		qcom_bam_unmap_sg(dev, bam_sgl, i, dir);
+
+	return ret;
+}
 #endif
-- 
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