dmaengine: Add support for APM X-Gene SoC DMA engine driver

This patch implements the APM X-Gene SoC DMA engine driver. The APM X-Gene
SoC DMA engine consists of 4 DMA channels for performing DMA operations.
These DMA operations include memory copy, scatter-gather memory copy,
raid5 xor, and raid6 p+q offloading.

Signed-off-by: Rameshwar Prasad Sahu <rsahu@apm.com>
Signed-off-by: Loc Ho <lho@apm.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

3 files changed, 2099 insertions, 0 deletions

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index ce09734248da..4be766f43aa9 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -435,6 +435,14 @@ config IMG_MDC_DMA
 	help
 	  Enable support for the IMG multi-threaded DMA controller (MDC).
 
+config XGENE_DMA
+	tristate "APM X-Gene DMA support"
+	select DMA_ENGINE
+	select DMA_ENGINE_RAID
+	select ASYNC_TX_ENABLE_CHANNEL_SWITCH
+	help
+	  Enable support for the APM X-Gene SoC DMA engine.
+
 config DMA_ENGINE
 	bool
 
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index af239e765cbb..1dab9ef196b0 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -52,3 +52,4 @@ obj-$(CONFIG_INTEL_MIC_X100_DMA) += mic_x100_dma.o
 obj-$(CONFIG_NBPFAXI_DMA) += nbpfaxi.o
 obj-$(CONFIG_DMA_SUN6I) += sun6i-dma.o
 obj-$(CONFIG_IMG_MDC_DMA) += img-mdc-dma.o
+obj-$(CONFIG_XGENE_DMA) += xgene-dma.o
diff --git a/drivers/dma/xgene-dma.c b/drivers/dma/xgene-dma.c
new file mode 100755
index 000000000000..2383528881f2
--- /dev/null
+++ b/drivers/dma/xgene-dma.c
@@ -0,0 +1,2090 @@
+/*
+ * Applied Micro X-Gene SoC DMA engine Driver
+ *
+ * Copyright (c) 2015, Applied Micro Circuits Corporation
+ * Authors: Rameshwar Prasad Sahu <rsahu@apm.com>
+ *	    Loc Ho <lho@apm.com>
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under  the terms of  the GNU General  Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * NOTE: PM support is currently not available.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/dmapool.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+
+#include "dmaengine.h"
+
+/* X-Gene DMA ring csr registers and bit definations */
+#define XGENE_DMA_RING_CONFIG			0x04
+#define XGENE_DMA_RING_ENABLE			BIT(31)
+#define XGENE_DMA_RING_ID			0x08
+#define XGENE_DMA_RING_ID_SETUP(v)		((v) | BIT(31))
+#define XGENE_DMA_RING_ID_BUF			0x0C
+#define XGENE_DMA_RING_ID_BUF_SETUP(v)		(((v) << 9) | BIT(21))
+#define XGENE_DMA_RING_THRESLD0_SET1		0x30
+#define XGENE_DMA_RING_THRESLD0_SET1_VAL	0X64
+#define XGENE_DMA_RING_THRESLD1_SET1		0x34
+#define XGENE_DMA_RING_THRESLD1_SET1_VAL	0xC8
+#define XGENE_DMA_RING_HYSTERESIS		0x68
+#define XGENE_DMA_RING_HYSTERESIS_VAL		0xFFFFFFFF
+#define XGENE_DMA_RING_STATE			0x6C
+#define XGENE_DMA_RING_STATE_WR_BASE		0x70
+#define XGENE_DMA_RING_NE_INT_MODE		0x017C
+#define XGENE_DMA_RING_NE_INT_MODE_SET(m, v)	\
+	((m) = ((m) & ~BIT(31 - (v))) | BIT(31 - (v)))
+#define XGENE_DMA_RING_NE_INT_MODE_RESET(m, v)	\
+	((m) &= (~BIT(31 - (v))))
+#define XGENE_DMA_RING_CLKEN			0xC208
+#define XGENE_DMA_RING_SRST			0xC200
+#define XGENE_DMA_RING_MEM_RAM_SHUTDOWN		0xD070
+#define XGENE_DMA_RING_BLK_MEM_RDY		0xD074
+#define XGENE_DMA_RING_BLK_MEM_RDY_VAL		0xFFFFFFFF
+#define XGENE_DMA_RING_DESC_CNT(v)		(((v) & 0x0001FFFE) >> 1)
+#define XGENE_DMA_RING_ID_GET(owner, num)	(((owner) << 6) | (num))
+#define XGENE_DMA_RING_DST_ID(v)		((1 << 10) | (v))
+#define XGENE_DMA_RING_CMD_OFFSET		0x2C
+#define XGENE_DMA_RING_CMD_BASE_OFFSET(v)	((v) << 6)
+#define XGENE_DMA_RING_COHERENT_SET(m)		\
+	(((u32 *)(m))[2] |= BIT(4))
+#define XGENE_DMA_RING_ADDRL_SET(m, v)		\
+	(((u32 *)(m))[2] |= (((v) >> 8) << 5))
+#define XGENE_DMA_RING_ADDRH_SET(m, v)		\
+	(((u32 *)(m))[3] |= ((v) >> 35))
+#define XGENE_DMA_RING_ACCEPTLERR_SET(m)	\
+	(((u32 *)(m))[3] |= BIT(19))
+#define XGENE_DMA_RING_SIZE_SET(m, v)		\
+	(((u32 *)(m))[3] |= ((v) << 23))
+#define XGENE_DMA_RING_RECOMBBUF_SET(m)		\
+	(((u32 *)(m))[3] |= BIT(27))
+#define XGENE_DMA_RING_RECOMTIMEOUTL_SET(m)	\
+	(((u32 *)(m))[3] |= (0x7 << 28))
+#define XGENE_DMA_RING_RECOMTIMEOUTH_SET(m)	\
+	(((u32 *)(m))[4] |= 0x3)
+#define XGENE_DMA_RING_SELTHRSH_SET(m)		\
+	(((u32 *)(m))[4] |= BIT(3))
+#define XGENE_DMA_RING_TYPE_SET(m, v)		\
+	(((u32 *)(m))[4] |= ((v) << 19))
+
+/* X-Gene DMA device csr registers and bit definitions */
+#define XGENE_DMA_IPBRR				0x0
+#define XGENE_DMA_DEV_ID_RD(v)			((v) & 0x00000FFF)
+#define XGENE_DMA_BUS_ID_RD(v)			(((v) >> 12) & 3)
+#define XGENE_DMA_REV_NO_RD(v)			(((v) >> 14) & 3)
+#define XGENE_DMA_GCR				0x10
+#define XGENE_DMA_CH_SETUP(v)			\
+	((v) = ((v) & ~0x000FFFFF) | 0x000AAFFF)
+#define XGENE_DMA_ENABLE(v)			((v) |= BIT(31))
+#define XGENE_DMA_DISABLE(v)			((v) &= ~BIT(31))
+#define XGENE_DMA_RAID6_CONT			0x14
+#define XGENE_DMA_RAID6_MULTI_CTRL(v)		((v) << 24)
+#define XGENE_DMA_INT				0x70
+#define XGENE_DMA_INT_MASK			0x74
+#define XGENE_DMA_INT_ALL_MASK			0xFFFFFFFF
+#define XGENE_DMA_INT_ALL_UNMASK		0x0
+#define XGENE_DMA_INT_MASK_SHIFT		0x14
+#define XGENE_DMA_RING_INT0_MASK		0x90A0
+#define XGENE_DMA_RING_INT1_MASK		0x90A8
+#define XGENE_DMA_RING_INT2_MASK		0x90B0
+#define XGENE_DMA_RING_INT3_MASK		0x90B8
+#define XGENE_DMA_RING_INT4_MASK		0x90C0
+#define XGENE_DMA_CFG_RING_WQ_ASSOC		0x90E0
+#define XGENE_DMA_ASSOC_RING_MNGR1		0xFFFFFFFF
+#define XGENE_DMA_MEM_RAM_SHUTDOWN		0xD070
+#define XGENE_DMA_BLK_MEM_RDY			0xD074
+#define XGENE_DMA_BLK_MEM_RDY_VAL		0xFFFFFFFF
+
+/* X-Gene SoC EFUSE csr register and bit defination */
+#define XGENE_SOC_JTAG1_SHADOW			0x18
+#define XGENE_DMA_PQ_DISABLE_MASK		BIT(13)
+
+/* X-Gene DMA Descriptor format */
+#define XGENE_DMA_DESC_NV_BIT			BIT_ULL(50)
+#define XGENE_DMA_DESC_IN_BIT			BIT_ULL(55)
+#define XGENE_DMA_DESC_C_BIT			BIT_ULL(63)
+#define XGENE_DMA_DESC_DR_BIT			BIT_ULL(61)
+#define XGENE_DMA_DESC_ELERR_POS		46
+#define XGENE_DMA_DESC_RTYPE_POS		56
+#define XGENE_DMA_DESC_LERR_POS			60
+#define XGENE_DMA_DESC_FLYBY_POS		4
+#define XGENE_DMA_DESC_BUFLEN_POS		48
+#define XGENE_DMA_DESC_HOENQ_NUM_POS		48
+
+#define XGENE_DMA_DESC_NV_SET(m)		\
+	(((u64 *)(m))[0] |= XGENE_DMA_DESC_NV_BIT)
+#define XGENE_DMA_DESC_IN_SET(m)		\
+	(((u64 *)(m))[0] |= XGENE_DMA_DESC_IN_BIT)
+#define XGENE_DMA_DESC_RTYPE_SET(m, v)		\
+	(((u64 *)(m))[0] |= ((u64)(v) << XGENE_DMA_DESC_RTYPE_POS))
+#define XGENE_DMA_DESC_BUFADDR_SET(m, v)	\
+	(((u64 *)(m))[0] |= (v))
+#define XGENE_DMA_DESC_BUFLEN_SET(m, v)		\
+	(((u64 *)(m))[0] |= ((u64)(v) << XGENE_DMA_DESC_BUFLEN_POS))
+#define XGENE_DMA_DESC_C_SET(m)			\
+	(((u64 *)(m))[1] |= XGENE_DMA_DESC_C_BIT)
+#define XGENE_DMA_DESC_FLYBY_SET(m, v)		\
+	(((u64 *)(m))[2] |= ((v) << XGENE_DMA_DESC_FLYBY_POS))
+#define XGENE_DMA_DESC_MULTI_SET(m, v, i)	\
+	(((u64 *)(m))[2] |= ((u64)(v) << (((i) + 1) * 8)))
+#define XGENE_DMA_DESC_DR_SET(m)		\
+	(((u64 *)(m))[2] |= XGENE_DMA_DESC_DR_BIT)
+#define XGENE_DMA_DESC_DST_ADDR_SET(m, v)	\
+	(((u64 *)(m))[3] |= (v))
+#define XGENE_DMA_DESC_H0ENQ_NUM_SET(m, v)	\
+	(((u64 *)(m))[3] |= ((u64)(v) << XGENE_DMA_DESC_HOENQ_NUM_POS))
+#define XGENE_DMA_DESC_ELERR_RD(m)		\
+	(((m) >> XGENE_DMA_DESC_ELERR_POS) & 0x3)
+#define XGENE_DMA_DESC_LERR_RD(m)		\
+	(((m) >> XGENE_DMA_DESC_LERR_POS) & 0x7)
+#define XGENE_DMA_DESC_STATUS(elerr, lerr)	\
+	(((elerr) << 4) | (lerr))
+
+/* X-Gene DMA descriptor empty s/w signature */
+#define XGENE_DMA_DESC_EMPTY_INDEX		0
+#define XGENE_DMA_DESC_EMPTY_SIGNATURE		~0ULL
+#define XGENE_DMA_DESC_SET_EMPTY(m)		\
+	(((u64 *)(m))[XGENE_DMA_DESC_EMPTY_INDEX] =	\
+	 XGENE_DMA_DESC_EMPTY_SIGNATURE)
+#define XGENE_DMA_DESC_IS_EMPTY(m)		\
+	(((u64 *)(m))[XGENE_DMA_DESC_EMPTY_INDEX] ==	\
+	 XGENE_DMA_DESC_EMPTY_SIGNATURE)
+
+/* X-Gene DMA configurable parameters defines */
+#define XGENE_DMA_RING_NUM		512
+#define XGENE_DMA_BUFNUM		0x0
+#define XGENE_DMA_CPU_BUFNUM		0x18
+#define XGENE_DMA_RING_OWNER_DMA	0x03
+#define XGENE_DMA_RING_OWNER_CPU	0x0F
+#define XGENE_DMA_RING_TYPE_REGULAR	0x01
+#define XGENE_DMA_RING_WQ_DESC_SIZE	32	/* 32 Bytes */
+#define XGENE_DMA_RING_NUM_CONFIG	5
+#define XGENE_DMA_MAX_CHANNEL		4
+#define XGENE_DMA_XOR_CHANNEL		0
+#define XGENE_DMA_PQ_CHANNEL		1
+#define XGENE_DMA_MAX_BYTE_CNT		0x4000	/* 16 KB */
+#define XGENE_DMA_MAX_64B_DESC_BYTE_CNT	0x14000	/* 80 KB */
+#define XGENE_DMA_XOR_ALIGNMENT		6	/* 64 Bytes */
+#define XGENE_DMA_MAX_XOR_SRC		5
+#define XGENE_DMA_16K_BUFFER_LEN_CODE	0x0
+#define XGENE_DMA_INVALID_LEN_CODE	0x7800
+
+/* X-Gene DMA descriptor error codes */
+#define ERR_DESC_AXI			0x01
+#define ERR_BAD_DESC			0x02
+#define ERR_READ_DATA_AXI		0x03
+#define ERR_WRITE_DATA_AXI		0x04
+#define ERR_FBP_TIMEOUT			0x05
+#define ERR_ECC				0x06
+#define ERR_DIFF_SIZE			0x08
+#define ERR_SCT_GAT_LEN			0x09
+#define ERR_CRC_ERR			0x11
+#define ERR_CHKSUM			0x12
+#define ERR_DIF				0x13
+
+/* X-Gene DMA error interrupt codes */
+#define ERR_DIF_SIZE_INT		0x0
+#define ERR_GS_ERR_INT			0x1
+#define ERR_FPB_TIMEO_INT		0x2
+#define ERR_WFIFO_OVF_INT		0x3
+#define ERR_RFIFO_OVF_INT		0x4
+#define ERR_WR_TIMEO_INT		0x5
+#define ERR_RD_TIMEO_INT		0x6
+#define ERR_WR_ERR_INT			0x7
+#define ERR_RD_ERR_INT			0x8
+#define ERR_BAD_DESC_INT		0x9
+#define ERR_DESC_DST_INT		0xA
+#define ERR_DESC_SRC_INT		0xB
+
+/* X-Gene DMA flyby operation code */
+#define FLYBY_2SRC_XOR			0x8
+#define FLYBY_3SRC_XOR			0x9
+#define FLYBY_4SRC_XOR			0xA
+#define FLYBY_5SRC_XOR			0xB
+
+/* X-Gene DMA SW descriptor flags */
+#define XGENE_DMA_FLAG_64B_DESC		BIT(0)
+
+/* Define to dump X-Gene DMA descriptor */
+#define XGENE_DMA_DESC_DUMP(desc, m)	\
+	print_hex_dump(KERN_ERR, (m),	\
+			DUMP_PREFIX_ADDRESS, 16, 8, (desc), 32, 0)
+
+#define to_dma_desc_sw(tx)		\
+	container_of(tx, struct xgene_dma_desc_sw, tx)
+#define to_dma_chan(dchan)		\
+	container_of(dchan, struct xgene_dma_chan, dma_chan)
+
+#define chan_dbg(chan, fmt, arg...)	\
+	dev_dbg(chan->dev, "%s: " fmt, chan->name, ##arg)
+#define chan_err(chan, fmt, arg...)	\
+	dev_err(chan->dev, "%s: " fmt, chan->name, ##arg)
+
+struct xgene_dma_desc_hw {
+	u64 m0;
+	u64 m1;
+	u64 m2;
+	u64 m3;
+};
+
+enum xgene_dma_ring_cfgsize {
+	XGENE_DMA_RING_CFG_SIZE_512B,
+	XGENE_DMA_RING_CFG_SIZE_2KB,
+	XGENE_DMA_RING_CFG_SIZE_16KB,
+	XGENE_DMA_RING_CFG_SIZE_64KB,
+	XGENE_DMA_RING_CFG_SIZE_512KB,
+	XGENE_DMA_RING_CFG_SIZE_INVALID
+};
+
+struct xgene_dma_ring {
+	struct xgene_dma *pdma;
+	u8 buf_num;
+	u16 id;
+	u16 num;
+	u16 head;
+	u16 owner;
+	u16 slots;
+	u16 dst_ring_num;
+	u32 size;
+	void __iomem *cmd;
+	void __iomem *cmd_base;
+	dma_addr_t desc_paddr;
+	u32 state[XGENE_DMA_RING_NUM_CONFIG];
+	enum xgene_dma_ring_cfgsize cfgsize;
+	union {
+		void *desc_vaddr;
+		struct xgene_dma_desc_hw *desc_hw;
+	};
+};
+
+struct xgene_dma_desc_sw {
+	struct xgene_dma_desc_hw desc1;
+	struct xgene_dma_desc_hw desc2;
+	u32 flags;
+	struct list_head node;
+	struct list_head tx_list;
+	struct dma_async_tx_descriptor tx;
+};
+
+/**
+ * struct xgene_dma_chan - internal representation of an X-Gene DMA channel
+ * @dma_chan: dmaengine channel object member
+ * @pdma: X-Gene DMA device structure reference
+ * @dev: struct device reference for dma mapping api
+ * @id: raw id of this channel
+ * @rx_irq: channel IRQ
+ * @name: name of X-Gene DMA channel
+ * @lock: serializes enqueue/dequeue operations to the descriptor pool
+ * @pending: number of transaction request pushed to DMA controller for
+ *	execution, but still waiting for completion,
+ * @max_outstanding: max number of outstanding request we can push to channel
+ * @ld_pending: descriptors which are queued to run, but have not yet been
+ *	submitted to the hardware for execution
+ * @ld_running: descriptors which are currently being executing by the hardware
+ * @ld_completed: descriptors which have finished execution by the hardware.
+ *	These descriptors have already had their cleanup actions run. They
+ *	are waiting for the ACK bit to be set by the async tx API.
+ * @desc_pool: descriptor pool for DMA operations
+ * @tasklet: bottom half where all completed descriptors cleans
+ * @tx_ring: transmit ring descriptor that we use to prepare actual
+ *	descriptors for further executions
+ * @rx_ring: receive ring descriptor that we use to get completed DMA
+ *	descriptors during cleanup time
+ */
+struct xgene_dma_chan {
+	struct dma_chan dma_chan;
+	struct xgene_dma *pdma;
+	struct device *dev;
+	int id;
+	int rx_irq;
+	char name[8];
+	spinlock_t lock;
+	int pending;
+	int max_outstanding;
+	struct list_head ld_pending;
+	struct list_head ld_running;
+	struct list_head ld_completed;
+	struct dma_pool *desc_pool;
+	struct tasklet_struct tasklet;
+	struct xgene_dma_ring tx_ring;
+	struct xgene_dma_ring rx_ring;
+};
+
+/**
+ * struct xgene_dma - internal representation of an X-Gene DMA device
+ * @err_irq: DMA error irq number
+ * @ring_num: start id number for DMA ring
+ * @csr_dma: base for DMA register access
+ * @csr_ring: base for DMA ring register access
+ * @csr_ring_cmd: base for DMA ring command register access
+ * @csr_efuse: base for efuse register access
+ * @dma_dev: embedded struct dma_device
+ * @chan: reference to X-Gene DMA channels
+ */
+struct xgene_dma {
+	struct device *dev;
+	struct clk *clk;
+	int err_irq;
+	int ring_num;
+	void __iomem *csr_dma;
+	void __iomem *csr_ring;
+	void __iomem *csr_ring_cmd;
+	void __iomem *csr_efuse;
+	struct dma_device dma_dev[XGENE_DMA_MAX_CHANNEL];
+	struct xgene_dma_chan chan[XGENE_DMA_MAX_CHANNEL];
+};
+
+static const char * const xgene_dma_desc_err[] = {
+	[ERR_DESC_AXI] = "AXI error when reading src/dst link list",
+	[ERR_BAD_DESC] = "ERR or El_ERR fields not set to zero in desc",
+	[ERR_READ_DATA_AXI] = "AXI error when reading data",
+	[ERR_WRITE_DATA_AXI] = "AXI error when writing data",
+	[ERR_FBP_TIMEOUT] = "Timeout on bufpool fetch",
+	[ERR_ECC] = "ECC double bit error",
+	[ERR_DIFF_SIZE] = "Bufpool too small to hold all the DIF result",
+	[ERR_SCT_GAT_LEN] = "Gather and scatter data length not same",
+	[ERR_CRC_ERR] = "CRC error",
+	[ERR_CHKSUM] = "Checksum error",
+	[ERR_DIF] = "DIF error",
+};
+
+static const char * const xgene_dma_err[] = {
+	[ERR_DIF_SIZE_INT] = "DIF size error",
+	[ERR_GS_ERR_INT] = "Gather scatter not same size error",
+	[ERR_FPB_TIMEO_INT] = "Free pool time out error",
+	[ERR_WFIFO_OVF_INT] = "Write FIFO over flow error",
+	[ERR_RFIFO_OVF_INT] = "Read FIFO over flow error",
+	[ERR_WR_TIMEO_INT] = "Write time out error",
+	[ERR_RD_TIMEO_INT] = "Read time out error",
+	[ERR_WR_ERR_INT] = "HBF bus write error",
+	[ERR_RD_ERR_INT] = "HBF bus read error",
+	[ERR_BAD_DESC_INT] = "Ring descriptor HE0 not set error",
+	[ERR_DESC_DST_INT] = "HFB reading dst link address error",
+	[ERR_DESC_SRC_INT] = "HFB reading src link address error",
+};
+
+static bool is_pq_enabled(struct xgene_dma *pdma)
+{
+	u32 val;
+
+	val = ioread32(pdma->csr_efuse + XGENE_SOC_JTAG1_SHADOW);
+	return !(val & XGENE_DMA_PQ_DISABLE_MASK);
+}
+
+static void xgene_dma_cpu_to_le64(u64 *desc, int count)
+{
+	int i;
+
+	for (i = 0; i < count; i++)
+		desc[i] = cpu_to_le64(desc[i]);
+}
+
+static u16 xgene_dma_encode_len(u32 len)
+{
+	return (len < XGENE_DMA_MAX_BYTE_CNT) ?
+		len : XGENE_DMA_16K_BUFFER_LEN_CODE;
+}
+
+static u8 xgene_dma_encode_xor_flyby(u32 src_cnt)
+{
+	static u8 flyby_type[] = {
+		FLYBY_2SRC_XOR, /* Dummy */
+		FLYBY_2SRC_XOR, /* Dummy */
+		FLYBY_2SRC_XOR,
+		FLYBY_3SRC_XOR,
+		FLYBY_4SRC_XOR,
+		FLYBY_5SRC_XOR
+	};
+
+	return flyby_type[src_cnt];
+}
+
+static u32 xgene_dma_ring_desc_cnt(struct xgene_dma_ring *ring)
+{
+	u32 __iomem *cmd_base = ring->cmd_base;
+	u32 ring_state = ioread32(&cmd_base[1]);
+
+	return XGENE_DMA_RING_DESC_CNT(ring_state);
+}
+
+static void xgene_dma_set_src_buffer(void *ext8, size_t *len,
+				     dma_addr_t *paddr)
+{
+	size_t nbytes = (*len < XGENE_DMA_MAX_BYTE_CNT) ?
+			*len : XGENE_DMA_MAX_BYTE_CNT;
+
+	XGENE_DMA_DESC_BUFADDR_SET(ext8, *paddr);
+	XGENE_DMA_DESC_BUFLEN_SET(ext8, xgene_dma_encode_len(nbytes));
+	*len -= nbytes;
+	*paddr += nbytes;
+}
+
+static void xgene_dma_invalidate_buffer(void *ext8)
+{
+	XGENE_DMA_DESC_BUFLEN_SET(ext8, XGENE_DMA_INVALID_LEN_CODE);
+}
+
+static void *xgene_dma_lookup_ext8(u64 *desc, int idx)
+{
+	return (idx % 2) ? (desc + idx - 1) : (desc + idx + 1);
+}
+
+static void xgene_dma_init_desc(void *desc, u16 dst_ring_num)
+{
+	XGENE_DMA_DESC_C_SET(desc); /* Coherent IO */
+	XGENE_DMA_DESC_IN_SET(desc);
+	XGENE_DMA_DESC_H0ENQ_NUM_SET(desc, dst_ring_num);
+	XGENE_DMA_DESC_RTYPE_SET(desc, XGENE_DMA_RING_OWNER_DMA);
+}
+
+static void xgene_dma_prep_cpy_desc(struct xgene_dma_chan *chan,
+				    struct xgene_dma_desc_sw *desc_sw,
+				    dma_addr_t dst, dma_addr_t src,
+				    size_t len)
+{
+	void *desc1, *desc2;
+	int i;
+
+	/* Get 1st descriptor */
+	desc1 = &desc_sw->desc1;
+	xgene_dma_init_desc(desc1, chan->tx_ring.dst_ring_num);
+
+	/* Set destination address */
+	XGENE_DMA_DESC_DR_SET(desc1);
+	XGENE_DMA_DESC_DST_ADDR_SET(desc1, dst);
+
+	/* Set 1st source address */
+	xgene_dma_set_src_buffer(desc1 + 8, &len, &src);
+
+	if (len <= 0) {
+		desc2 = NULL;
+		goto skip_additional_src;
+	}
+
+	/*
+	 * We need to split this source buffer,
+	 * and need to use 2nd descriptor
+	 */
+	desc2 = &desc_sw->desc2;
+	XGENE_DMA_DESC_NV_SET(desc1);
+
+	/* Set 2nd to 5th source address */
+	for (i = 0; i < 4 && len; i++)
+		xgene_dma_set_src_buffer(xgene_dma_lookup_ext8(desc2, i),
+					 &len, &src);
+
+	/* Invalidate unused source address field */
+	for (; i < 4; i++)
+		xgene_dma_invalidate_buffer(xgene_dma_lookup_ext8(desc2, i));
+
+	/* Updated flag that we have prepared 64B descriptor */
+	desc_sw->flags |= XGENE_DMA_FLAG_64B_DESC;
+
+skip_additional_src:
+	/* Hardware stores descriptor in little endian format */
+	xgene_dma_cpu_to_le64(desc1, 4);
+	if (desc2)
+		xgene_dma_cpu_to_le64(desc2, 4);
+}
+
+static void xgene_dma_prep_xor_desc(struct xgene_dma_chan *chan,
+				    struct xgene_dma_desc_sw *desc_sw,
+				    dma_addr_t *dst, dma_addr_t *src,
+				    u32 src_cnt, size_t *nbytes,
+				    const u8 *scf)
+{
+	void *desc1, *desc2;
+	size_t len = *nbytes;
+	int i;
+
+	desc1 = &desc_sw->desc1;
+	desc2 = &desc_sw->desc2;
+
+	/* Initialize DMA descriptor */
+	xgene_dma_init_desc(desc1, chan->tx_ring.dst_ring_num);
+
+	/* Set destination address */
+	XGENE_DMA_DESC_DR_SET(desc1);
+	XGENE_DMA_DESC_DST_ADDR_SET(desc1, *dst);
+
+	/* We have multiple source addresses, so need to set NV bit*/
+	XGENE_DMA_DESC_NV_SET(desc1);
+
+	/* Set flyby opcode */
+	XGENE_DMA_DESC_FLYBY_SET(desc1, xgene_dma_encode_xor_flyby(src_cnt));
+
+	/* Set 1st to 5th source addresses */
+	for (i = 0; i < src_cnt; i++) {
+		len = *nbytes;
+		xgene_dma_set_src_buffer((i == 0) ? (desc1 + 8) :
+					 xgene_dma_lookup_ext8(desc2, i - 1),
+					 &len, &src[i]);
+		XGENE_DMA_DESC_MULTI_SET(desc1, scf[i], i);
+	}
+
+	/* Hardware stores descriptor in little endian format */
+	xgene_dma_cpu_to_le64(desc1, 4);
+	xgene_dma_cpu_to_le64(desc2, 4);
+
+	/* Update meta data */
+	*nbytes = len;
+	*dst += XGENE_DMA_MAX_BYTE_CNT;
+
+	/* We need always 64B descriptor to perform xor or pq operations */
+	desc_sw->flags |= XGENE_DMA_FLAG_64B_DESC;
+}
+
+static dma_cookie_t xgene_dma_tx_submit(struct dma_async_tx_descriptor *tx)
+{
+	struct xgene_dma_desc_sw *desc;
+	struct xgene_dma_chan *chan;
+	dma_cookie_t cookie;
+
+	if (unlikely(!tx))
+		return -EINVAL;
+
+	chan = to_dma_chan(tx->chan);
+	desc = to_dma_desc_sw(tx);
+
+	spin_lock_bh(&chan->lock);
+
+	cookie = dma_cookie_assign(tx);
+
+	/* Add this transaction list onto the tail of the pending queue */
+	list_splice_tail_init(&desc->tx_list, &chan->ld_pending);
+
+	spin_unlock_bh(&chan->lock);
+
+	return cookie;
+}
+
+static void xgene_dma_clean_descriptor(struct xgene_dma_chan *chan,
+				       struct xgene_dma_desc_sw *desc)
+{
+	list_del(&desc->node);
+	chan_dbg(chan, "LD %p free\n", desc);
+	dma_pool_free(chan->desc_pool, desc, desc->tx.phys);
+}
+
+static struct xgene_dma_desc_sw *xgene_dma_alloc_descriptor(
+				 struct xgene_dma_chan *chan)
+{
+	struct xgene_dma_desc_sw *desc;
+	dma_addr_t phys;
+
+	desc = dma_pool_alloc(chan->desc_pool, GFP_NOWAIT, &phys);
+	if (!desc) {
+		chan_err(chan, "Failed to allocate LDs\n");
+		return NULL;
+	}
+
+	memset(desc, 0, sizeof(*desc));
+
+	INIT_LIST_HEAD(&desc->tx_list);
+	desc->tx.phys = phys;
+	desc->tx.tx_submit = xgene_dma_tx_submit;
+	dma_async_tx_descriptor_init(&desc->tx, &chan->dma_chan);
+
+	chan_dbg(chan, "LD %p allocated\n", desc);
+
+	return desc;
+}
+
+/**
+ * xgene_dma_clean_completed_descriptor - free all descriptors which
+ * has been completed and acked
+ * @chan: X-Gene DMA channel
+ *
+ * This function is used on all completed and acked descriptors.
+ */
+static void xgene_dma_clean_completed_descriptor(struct xgene_dma_chan *chan)
+{
+	struct xgene_dma_desc_sw *desc, *_desc;
+
+	/* Run the callback for each descriptor, in order */
+	list_for_each_entry_safe(desc, _desc, &chan->ld_completed, node) {
+		if (async_tx_test_ack(&desc->tx))
+			xgene_dma_clean_descriptor(chan, desc);
+	}
+}
+
+/**
+ * xgene_dma_run_tx_complete_actions - cleanup a single link descriptor
+ * @chan: X-Gene DMA channel
+ * @desc: descriptor to cleanup and free
+ *
+ * This function is used on a descriptor which has been executed by the DMA
+ * controller. It will run any callbacks, submit any dependencies.
+ */
+static void xgene_dma_run_tx_complete_actions(struct xgene_dma_chan *chan,
+					      struct xgene_dma_desc_sw *desc)
+{
+	struct dma_async_tx_descriptor *tx = &desc->tx;
+
+	/*
+	 * If this is not the last transaction in the group,
+	 * then no need to complete cookie and run any callback as
+	 * this is not the tx_descriptor which had been sent to caller
+	 * of this DMA request
+	 */
+
+	if (tx->cookie == 0)
+		return;
+
+	dma_cookie_complete(tx);
+
+	/* Run the link descriptor callback function */
+	if (tx->callback)
+		tx->callback(tx->callback_param);
+
+	dma_descriptor_unmap(tx);
+
+	/* Run any dependencies */
+	dma_run_dependencies(tx);
+}
+
+/**
+ * xgene_dma_clean_running_descriptor - move the completed descriptor from
+ * ld_running to ld_completed
+ * @chan: X-Gene DMA channel
+ * @desc: the descriptor which is completed
+ *
+ * Free the descriptor directly if acked by async_tx api,
+ * else move it to queue ld_completed.
+ */
+static void xgene_dma_clean_running_descriptor(struct xgene_dma_chan *chan,
+					       struct xgene_dma_desc_sw *desc)
+{
+	/* Remove from the list of running transactions */
+	list_del(&desc->node);
+
+	/*
+	 * the client is allowed to attach dependent operations
+	 * until 'ack' is set
+	 */
+	if (!async_tx_test_ack(&desc->tx)) {
+		/*
+		 * Move this descriptor to the list of descriptors which is
+		 * completed, but still awaiting the 'ack' bit to be set.
+		 */
+		list_add_tail(&desc->node, &chan->ld_completed);
+		return;
+	}
+
+	chan_dbg(chan, "LD %p free\n", desc);
+	dma_pool_free(chan->desc_pool, desc, desc->tx.phys);
+}
+
+static int xgene_chan_xfer_request(struct xgene_dma_ring *ring,
+				   struct xgene_dma_desc_sw *desc_sw)
+{
+	struct xgene_dma_desc_hw *desc_hw;
+
+	/* Check if can push more descriptor to hw for execution */
+	if (xgene_dma_ring_desc_cnt(ring) > (ring->slots - 2))
+		return -EBUSY;
+
+	/* Get hw descriptor from DMA tx ring */
+	desc_hw = &ring->desc_hw[ring->head];
+
+	/*
+	 * Increment the head count to point next
+	 * descriptor for next time
+	 */
+	if (++ring->head == ring->slots)
+		ring->head = 0;
+
+	/* Copy prepared sw descriptor data to hw descriptor */
+	memcpy(desc_hw, &desc_sw->desc1, sizeof(*desc_hw));
+
+	/*
+	 * Check if we have prepared 64B descriptor,
+	 * in this case we need one more hw descriptor
+	 */
+	if (desc_sw->flags & XGENE_DMA_FLAG_64B_DESC) {
+		desc_hw = &ring->desc_hw[ring->head];
+
+		if (++ring->head == ring->slots)
+			ring->head = 0;
+
+		memcpy(desc_hw, &desc_sw->desc2, sizeof(*desc_hw));
+	}
+
+	/* Notify the hw that we have descriptor ready for execution */
+	iowrite32((desc_sw->flags & XGENE_DMA_FLAG_64B_DESC) ?
+		  2 : 1, ring->cmd);
+
+	return 0;
+}
+
+/**
+ * xgene_chan_xfer_ld_pending - push any pending transactions to hw
+ * @chan : X-Gene DMA channel
+ *
+ * LOCKING: must hold chan->desc_lock
+ */
+static void xgene_chan_xfer_ld_pending(struct xgene_dma_chan *chan)
+{
+	struct xgene_dma_desc_sw *desc_sw, *_desc_sw;
+	int ret;
+
+	/*
+	 * If the list of pending descriptors is empty, then we
+	 * don't need to do any work at all
+	 */
+	if (list_empty(&chan->ld_pending)) {
+		chan_dbg(chan, "No pending LDs\n");
+		return;
+	}
+
+	/*
+	 * Move elements from the queue of pending transactions onto the list
+	 * of running transactions and push it to hw for further executions
+	 */
+	list_for_each_entry_safe(desc_sw, _desc_sw, &chan->ld_pending, node) {
+		/*
+		 * Check if have pushed max number of transactions to hw
+		 * as capable, so let's stop here and will push remaining
+		 * elements from pening ld queue after completing some
+		 * descriptors that we have already pushed
+		 */
+		if (chan->pending >= chan->max_outstanding)
+			return;
+
+		ret = xgene_chan_xfer_request(&chan->tx_ring, desc_sw);
+		if (ret)
+			return;
+
+		/*
+		 * Delete this element from ld pending queue and append it to
+		 * ld running queue
+		 */
+		list_move_tail(&desc_sw->node, &chan->ld_running);
+
+		/* Increment the pending transaction count */
+		chan->pending++;
+	}
+}
+
+/**
+ * xgene_dma_cleanup_descriptors - cleanup link descriptors which are completed
+ * and move them to ld_completed to free until flag 'ack' is set
+ * @chan: X-Gene DMA channel
+ *
+ * This function is used on descriptors which have been executed by the DMA
+ * controller. It will run any callbacks, submit any dependencies, then
+ * free these descriptors if flag 'ack' is set.
+ */
+static void xgene_dma_cleanup_descriptors(struct xgene_dma_chan *chan)
+{
+	struct xgene_dma_ring *ring = &chan->rx_ring;
+	struct xgene_dma_desc_sw *desc_sw, *_desc_sw;
+	struct xgene_dma_desc_hw *desc_hw;
+	u8 status;
+
+	/* Clean already completed and acked descriptors */
+	xgene_dma_clean_completed_descriptor(chan);
+
+	/* Run the callback for each descriptor, in order */
+	list_for_each_entry_safe(desc_sw, _desc_sw, &chan->ld_running, node) {
+		/* Get subsequent hw descriptor from DMA rx ring */
+		desc_hw = &ring->desc_hw[ring->head];
+
+		/* Check if this descriptor has been completed */
+		if (unlikely(XGENE_DMA_DESC_IS_EMPTY(desc_hw)))
+			break;
+
+		if (++ring->head == ring->slots)
+			ring->head = 0;
+
+		/* Check if we have any error with DMA transactions */
+		status = XGENE_DMA_DESC_STATUS(
+				XGENE_DMA_DESC_ELERR_RD(le64_to_cpu(
+							desc_hw->m0)),
+				XGENE_DMA_DESC_LERR_RD(le64_to_cpu(
+						       desc_hw->m0)));
+		if (status) {
+			/* Print the DMA error type */
+			chan_err(chan, "%s\n", xgene_dma_desc_err[status]);
+
+			/*
+			 * We have DMA transactions error here. Dump DMA Tx
+			 * and Rx descriptors for this request */
+			XGENE_DMA_DESC_DUMP(&desc_sw->desc1,
+					    "X-Gene DMA TX DESC1: ");
+
+			if (desc_sw->flags & XGENE_DMA_FLAG_64B_DESC)
+				XGENE_DMA_DESC_DUMP(&desc_sw->desc2,
+						    "X-Gene DMA TX DESC2: ");
+
+			XGENE_DMA_DESC_DUMP(desc_hw,
+					    "X-Gene DMA RX ERR DESC: ");
+		}
+
+		/* Notify the hw about this completed descriptor */
+		iowrite32(-1, ring->cmd);
+
+		/* Mark this hw descriptor as processed */
+		XGENE_DMA_DESC_SET_EMPTY(desc_hw);
+
+		xgene_dma_run_tx_complete_actions(chan, desc_sw);
+
+		xgene_dma_clean_running_descriptor(chan, desc_sw);
+
+		/*
+		 * Decrement the pending transaction count
+		 * as we have processed one
+		 */
+		chan->pending--;
+	}
+
+	/*
+	 * Start any pending transactions automatically
+	 * In the ideal case, we keep the DMA controller busy while we go
+	 * ahead and free the descriptors below.
+	 */
+	xgene_chan_xfer_ld_pending(chan);
+}
+
+static int xgene_dma_alloc_chan_resources(struct dma_chan *dchan)
+{
+	struct xgene_dma_chan *chan = to_dma_chan(dchan);
+
+	/* Has this channel already been allocated? */
+	if (chan->desc_pool)
+		return 1;
+
+	chan->desc_pool = dma_pool_create(chan->name, chan->dev,
+					  sizeof(struct xgene_dma_desc_sw),
+					  0, 0);
+	if (!chan->desc_pool) {
+		chan_err(chan, "Failed to allocate descriptor pool\n");
+		return -ENOMEM;
+	}
+
+	chan_dbg(chan, "Allocate descripto pool\n");
+
+	return 1;
+}
+
+/**
+ * xgene_dma_free_desc_list - Free all descriptors in a queue
+ * @chan: X-Gene DMA channel
+ * @list: the list to free
+ *
+ * LOCKING: must hold chan->desc_lock
+ */
+static void xgene_dma_free_desc_list(struct xgene_dma_chan *chan,
+				     struct list_head *list)
+{
+	struct xgene_dma_desc_sw *desc, *_desc;
+
+	list_for_each_entry_safe(desc, _desc, list, node)
+		xgene_dma_clean_descriptor(chan, desc);
+}
+
+static void xgene_dma_free_tx_desc_list(struct xgene_dma_chan *chan,
+					struct list_head *list)
+{
+	struct xgene_dma_desc_sw *desc, *_desc;
+
+	list_for_each_entry_safe(desc, _desc, list, node)
+		xgene_dma_clean_descriptor(chan, desc);
+}
+
+static void xgene_dma_free_chan_resources(struct dma_chan *dchan)
+{
+	struct xgene_dma_chan *chan = to_dma_chan(dchan);
+
+	chan_dbg(chan, "Free all resources\n");
+
+	if (!chan->desc_pool)
+		return;
+
+	spin_lock_bh(&chan->lock);
+
+	/* Process all running descriptor */
+	xgene_dma_cleanup_descriptors(chan);
+
+	/* Clean all link descriptor queues */
+	xgene_dma_free_desc_list(chan, &chan->ld_pending);
+	xgene_dma_free_desc_list(chan, &chan->ld_running);
+	xgene_dma_free_desc_list(chan, &chan->ld_completed);
+
+	spin_unlock_bh(&chan->lock);
+
+	/* Delete this channel DMA pool */
+	dma_pool_destroy(chan->desc_pool);
+	chan->desc_pool = NULL;
+}
+
+static struct dma_async_tx_descriptor *xgene_dma_prep_memcpy(
+	struct dma_chan *dchan, dma_addr_t dst, dma_addr_t src,
+	size_t len, unsigned long flags)
+{
+	struct xgene_dma_desc_sw *first = NULL, *new;
+	struct xgene_dma_chan *chan;
+	size_t copy;
+
+	if (unlikely(!dchan || !len))
+		return NULL;
+
+	chan = to_dma_chan(dchan);
+
+	do {
+		/* Allocate the link descriptor from DMA pool */
+		new = xgene_dma_alloc_descriptor(chan);
+		if (!new)
+			goto fail;
+
+		/* Create the largest transaction possible */
+		copy = min_t(size_t, len, XGENE_DMA_MAX_64B_DESC_BYTE_CNT);
+
+		/* Prepare DMA descriptor */
+		xgene_dma_prep_cpy_desc(chan, new, dst, src, copy);
+
+		if (!first)
+			first = new;
+
+		new->tx.cookie = 0;
+		async_tx_ack(&new->tx);
+
+		/* Update metadata */
+		len -= copy;
+		dst += copy;
+		src += copy;
+
+		/* Insert the link descriptor to the LD ring */
+		list_add_tail(&new->node, &first->tx_list);
+	} while (len);
+
+	new->tx.flags = flags; /* client is in control of this ack */
+	new->tx.cookie = -EBUSY;
+	list_splice(&first->tx_list, &new->tx_list);
+
+	return &new->tx;
+
+fail:
+	if (!first)
+		return NULL;
+
+	xgene_dma_free_tx_desc_list(chan, &first->tx_list);
+	return NULL;
+}
+
+static struct dma_async_tx_descriptor *xgene_dma_prep_sg(
+	struct dma_chan *dchan, struct scatterlist *dst_sg,
+	u32 dst_nents, struct scatterlist *src_sg,
+	u32 src_nents, unsigned long flags)
+{
+	struct xgene_dma_desc_sw *first = NULL, *new = NULL;
+	struct xgene_dma_chan *chan;
+	size_t dst_avail, src_avail;
+	dma_addr_t dst, src;
+	size_t len;
+
+	if (unlikely(!dchan))
+		return NULL;
+
+	if (unlikely(!dst_nents || !src_nents))
+		return NULL;
+
+	if (unlikely(!dst_sg || !src_sg))
+		return NULL;
+
+	chan = to_dma_chan(dchan);
+
+	/* Get prepared for the loop */
+	dst_avail = sg_dma_len(dst_sg);
+	src_avail = sg_dma_len(src_sg);
+	dst_nents--;
+	src_nents--;
+
+	/* Run until we are out of scatterlist entries */
+	while (true) {
+		/* Create the largest transaction possible */
+		len = min_t(size_t, src_avail, dst_avail);
+		len = min_t(size_t, len, XGENE_DMA_MAX_64B_DESC_BYTE_CNT);
+		if (len == 0)
+			goto fetch;
+
+		dst = sg_dma_address(dst_sg) + sg_dma_len(dst_sg) - dst_avail;
+		src = sg_dma_address(src_sg) + sg_dma_len(src_sg) - src_avail;
+
+		/* Allocate the link descriptor from DMA pool */
+		new = xgene_dma_alloc_descriptor(chan);
+		if (!new)
+			goto fail;
+
+		/* Prepare DMA descriptor */
+		xgene_dma_prep_cpy_desc(chan, new, dst, src, len);
+
+		if (!first)
+			first = new;
+
+		new->tx.cookie = 0;
+		async_tx_ack(&new->tx);
+
+		/* update metadata */
+		dst_avail -= len;
+		src_avail -= len;
+
+		/* Insert the link descriptor to the LD ring */
+		list_add_tail(&new->node, &first->tx_list);
+
+fetch:
+		/* fetch the next dst scatterlist entry */
+		if (dst_avail == 0) {
+			/* no more entries: we're done */
+			if (dst_nents == 0)
+				break;
+
+			/* fetch the next entry: if there are no more: done */
+			dst_sg = sg_next(dst_sg);
+			if (!dst_sg)
+				break;
+
+			dst_nents--;
+			dst_avail = sg_dma_len(dst_sg);
+		}
+