linux-kernel - [PATCH v3 2/3] dmaengine: qcom: bam_dma: wrapper functions for command descriptor

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Date:   Tue,  1 Aug 2017 19:41:43 +0530
From:   Abhishek Sahu <absahu@...eaurora.org>
To:     vinod.koul@...el.com, corbet@....net, dan.j.williams@...el.com
Cc:     andy.gross@...aro.org, david.brown@...aro.org,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, Abhishek Sahu <absahu@...eaurora.org>
Subject: [PATCH v3 2/3] dmaengine: qcom: bam_dma: wrapper functions for command descriptor

QCOM BAM also supports command descriptor which allows the SW to
create descriptors of type command which does not generate any
data transmissions but configures registers in the peripheral.
In command descriptor the 32bit address point to the start of
the command block which holds the command elements and the
16bit size define the size of the command block.

Each Command Element is structured by 4 words:
    Write command: address + cmd
                   register data
                   register mask
                   reserved

    Read command: address + cmd
                  read data result address,
                  reserved
                  reserved

This patch creates a new header file for BAM driver which contains the
structures and wrapper functions for command descriptor. This file will
be used by different QCOM peripheral drivers for forming the command
descriptor

Signed-off-by: Abhishek Sahu <absahu@...eaurora.org>
---
 include/linux/dma/qcom_bam_dma.h | 79 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 include/linux/dma/qcom_bam_dma.h

diff --git a/include/linux/dma/qcom_bam_dma.h b/include/linux/dma/qcom_bam_dma.h
new file mode 100644
index 0000000..077d43a
--- /dev/null
+++ b/include/linux/dma/qcom_bam_dma.h
@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2016-2017, The Linux Foundation. All rights reserved.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _QCOM_BAM_DMA_H
+#define _QCOM_BAM_DMA_H
+
+#include <asm/byteorder.h>
+
+/*
+ * This data type corresponds to the native Command Element
+ * supported by BAM DMA Engine.
+ *
+ * @cmd_and_addr - upper 8 bits command and lower 24 bits register address.
+ * @data - for write command: content to be written into peripheral register.
+ *	   for read command: dest addr to write peripheral register value.
+ * @mask - register mask.
+ * @reserved - for future usage.
+ *
+ */
+struct bam_cmd_element {
+	__le32 cmd_and_addr;
+	__le32 data;
+	__le32 mask;
+	__le32 reserved;
+};
+
+/*
+ * This enum indicates the command type in a command element
+ */
+enum bam_command_type {
+	BAM_WRITE_COMMAND = 0,
+	BAM_READ_COMMAND,
+};
+
+/*
+ * prep_bam_ce_le32 - Wrapper function to prepare a single BAM command
+ * element with the data already in le32 format.
+ *
+ * @bam_ce: bam command element
+ * @addr: target address
+ * @cmd: BAM command
+ * @data: actual data for write and dest addr for read in le32
+ */
+static inline void
+bam_prep_ce_le32(struct bam_cmd_element *bam_ce, u32 addr,
+		 enum bam_command_type cmd, __le32 data)
+{
+	bam_ce->cmd_and_addr =
+		cpu_to_le32((addr & 0xffffff) | ((cmd & 0xff) << 24));
+	bam_ce->data = data;
+	bam_ce->mask = cpu_to_le32(0xffffffff);
+}
+
+/*
+ * bam_prep_ce - Wrapper function to prepare a single BAM command element
+ * with the data.
+ *
+ * @bam_ce: BAM command element
+ * @addr: target address
+ * @cmd: BAM command
+ * @data: actual data for write and dest addr for read
+ */
+static inline void
+bam_prep_ce(struct bam_cmd_element *bam_ce, u32 addr,
+	    enum bam_command_type cmd, u32 data)
+{
+	bam_prep_ce_le32(bam_ce, addr, cmd, cpu_to_le32(data));
+}
+#endif
-- 
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