[PATCH 2/2] dmaengine: Add STM32 MDMA driver

[M'boumba Cedric Madianga]

This patch adds the driver for the STM32 MDMA controller.

Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@xxxxxxxxx>
Reviewed-by: Ludovic BARRE <ludovic.barre@xxxxxx>
---
 drivers/dma/Kconfig      |   12 +
 drivers/dma/Makefile     |    1 +
 drivers/dma/stm32-mdma.c | 1570 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 1583 insertions(+)
 create mode 100644 drivers/dma/stm32-mdma.c

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index 6ab80c9..beae8b0 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -470,6 +470,18 @@ config STM32_DMAMUX
 	  If you have a board based on such a MCU and wish to use DMAMUX say Y
 	  here.
 
+config STM32_MDMA
+	bool "STMicroelectronics STM32 master dma support"
+	depends on ARCH_STM32  || COMPILE_TEST
+	select DMA_ENGINE
+	select DMA_OF
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  Enable support for the on-chip MDMA controller on STMicroelectronics
+	  STM32 platforms.
+	  If you have a board based on STM32 SoC and wish to use the master DMA
+	  say Y here.
+
 config S3C24XX_DMAC
 	bool "Samsung S3C24XX DMA support"
 	depends on ARCH_S3C24XX || COMPILE_TEST
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index 449c7a3..003b515 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -58,6 +58,7 @@ obj-$(CONFIG_SIRF_DMA) += sirf-dma.o
 obj-$(CONFIG_STE_DMA40) += ste_dma40.o ste_dma40_ll.o
 obj-$(CONFIG_STM32_DMA) += stm32-dma.o
 obj-$(CONFIG_STM32_DMAMUX) += stm32-dmamux.o
+obj-$(CONFIG_STM32_MDMA) += stm32-mdma.o
 obj-$(CONFIG_S3C24XX_DMAC) += s3c24xx-dma.o
 obj-$(CONFIG_TXX9_DMAC) += txx9dmac.o
 obj-$(CONFIG_TEGRA20_APB_DMA) += tegra20-apb-dma.o
diff --git a/drivers/dma/stm32-mdma.c b/drivers/dma/stm32-mdma.c
new file mode 100644
index 0000000..23d267c
--- /dev/null
+++ b/drivers/dma/stm32-mdma.c
@@ -0,0 +1,1570 @@
+/*
+ * Driver for STM32 MDMA controller
+ *
+ * Inspired by stm32-dma.c and dma-jz4780.c
+ *
+ * Copyright (C) M'boumba Cedric Madianga 2017
+ * Author: M'boumba Cedric Madianga <cedric.madianga@xxxxxxxxx>
+ *
+ * License terms:  GNU General Public License (GPL), version 2
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmapool.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/iopoll.h>
+#include <linux/jiffies.h>
+#include <linux/list.h>
+#include <linux/log2.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_dma.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+#include "virt-dma.h"
+
+#define STM32_MDMA_GISR0		0x0000 /* MDMA Int Status Reg 1 */
+#define STM32_MDMA_GISR1		0x0004 /* MDMA Int Status Reg 2 */
+
+/* MDMA Channel x interrupt/status register */
+#define STM32_MDMA_CISR(x)		(0x40 + 0x40 * (x)) /* x = 0..62 */
+#define STM32_MDMA_CISR_CRQA		BIT(16)
+#define STM32_MDMA_CISR_TCIF		BIT(4)
+#define STM32_MDMA_CISR_BTIF		BIT(3)
+#define STM32_MDMA_CISR_BRTIF		BIT(2)
+#define STM32_MDMA_CISR_CTCIF		BIT(1)
+#define STM32_MDMA_CISR_TEIF		BIT(0)
+
+/* MDMA Channel x interrupt flag clear register */
+#define STM32_MDMA_CIFCR(x)		(0x44 + 0x40 * (x))
+#define STM32_MDMA_CIFCR_CLTCIF		BIT(4)
+#define STM32_MDMA_CIFCR_CBTIF		BIT(3)
+#define STM32_MDMA_CIFCR_CBRTIF		BIT(2)
+#define STM32_MDMA_CIFCR_CCTCIF		BIT(1)
+#define STM32_MDMA_CIFCR_CTEIF		BIT(0)
+#define STM32_MDMA_CIFCR_CLEAR_ALL	(STM32_MDMA_CIFCR_CLTCIF \
+					| STM32_MDMA_CIFCR_CBTIF \
+					| STM32_MDMA_CIFCR_CBRTIF \
+					| STM32_MDMA_CIFCR_CCTCIF \
+					| STM32_MDMA_CIFCR_CTEIF)
+
+/* MDMA Channel x error status register */
+#define STM32_MDMA_CESR(x)		(0x48 + 0x40 * (x))
+#define STM32_MDMA_CESR_BSE		BIT(11)
+#define STM32_MDMA_CESR_ASR		BIT(10)
+#define STM32_MDMA_CESR_TEMD		BIT(9)
+#define STM32_MDMA_CESR_TELD		BIT(8)
+#define STM32_MDMA_CESR_TED		BIT(7)
+#define STM32_MDMA_CESR_TEA_MASK	GENMASK(6, 0)
+
+/* MDMA Channel x control register */
+#define STM32_MDMA_CCR(x)		(0x4C + 0x40 * (x))
+#define STM32_MDMA_CCR_SWRQ		BIT(16)
+#define STM32_MDMA_CCR_WEX		BIT(14)
+#define STM32_MDMA_CCR_HEX		BIT(13)
+#define STM32_MDMA_CCR_BEX		BIT(12)
+#define STM32_MDMA_CCR_PL_MASK		GENMASK(7, 6)
+#define STM32_MDMA_CCR_PL(n)		(((n) & 0x3) << 6)
+#define STM32_MDMA_CCR_TCIE		BIT(5)
+#define STM32_MDMA_CCR_BTIE		BIT(4)
+#define STM32_MDMA_CCR_BRTIE		BIT(3)
+#define STM32_MDMA_CCR_CTCIE		BIT(2)
+#define STM32_MDMA_CCR_TEIE		BIT(1)
+#define STM32_MDMA_CCR_EN		BIT(0)
+#define STM32_MDMA_CCR_IRQ_MASK		(STM32_MDMA_CCR_TCIE \
+					| STM32_MDMA_CCR_BTIE \
+					| STM32_MDMA_CCR_BRTIE \
+					| STM32_MDMA_CCR_CTCIE \
+					| STM32_MDMA_CCR_TEIE)
+
+/* MDMA Channel x transfer configuration register */
+#define STM32_MDMA_CTCR(x)		(0x50 + 0x40 * (x))
+#define STM32_MDMA_CTCR_BWM		BIT(31)
+#define STM32_MDMA_CTCR_SWRM		BIT(30)
+#define STM32_MDMA_CTCR_TRGM_MSK	GENMASK(29, 28)
+#define STM32_MDMA_CTCR_TRGM(n)		(((n) & 0x3) << 28)
+#define STM32_MDMA_CTCR_TRGM_GET(n)	(((n) & STM32_MDMA_CTCR_TRGM_MSK) >> 28)
+#define STM32_MDMA_CTCR_PAM_MASK	GENMASK(27, 26)
+#define STM32_MDMA_CTCR_PAM(n)		(((n) & 0x3) << 26)
+#define STM32_MDMA_CTCR_PKE		BIT(25)
+#define STM32_MDMA_CTCR_TLEN_MSK	GENMASK(24, 18)
+#define STM32_MDMA_CTCR_TLEN(n)		(((n) & 0x7f) << 18)
+#define STM32_MDMA_CTCR_TLEN_GET(n)	(((n) & STM32_MDMA_CTCR_TLEN_MSK) >> 18)
+#define STM32_MDMA_CTCR_LEN2_MSK	GENMASK(25, 18)
+#define STM32_MDMA_CTCR_LEN2(n)	(((n) & 0xff) << 18)
+#define STM32_MDMA_CTCR_LEN2_GET(n)	(((n) & STM32_MDMA_CTCR_LEN2_MSK) >> 18)
+#define STM32_MDMA_CTCR_DBURST_MASK	GENMASK(17, 15)
+#define STM32_MDMA_CTCR_DBURST(n)	(((n) & 0x7) << 15)
+#define STM32_MDMA_CTCR_SBURST_MASK	GENMASK(14, 12)
+#define STM32_MDMA_CTCR_SBURST(n)	(((n) & 0x7) << 12)
+#define STM32_MDMA_CTCR_DINCOS_MASK	GENMASK(11, 10)
+#define STM32_MDMA_CTCR_DINCOS(n)	(((n) & 0x3) << 10)
+#define STM32_MDMA_CTCR_SINCOS_MASK	GENMASK(9, 8)
+#define STM32_MDMA_CTCR_SINCOS(n)	(((n) & 0x3) << 8)
+#define STM32_MDMA_CTCR_DSIZE_MASK	GENMASK(7, 6)
+#define STM32_MDMA_CTCR_DSIZE(n)	(((n) & 0x3) << 6)
+#define STM32_MDMA_CTCR_SSIZE_MASK	GENMASK(5, 4)
+#define STM32_MDMA_CTCR_SSIZE(n)	(((n) & 0x3) << 4)
+#define STM32_MDMA_CTCR_DINC_MASK	GENMASK(3, 2)
+#define STM32_MDMA_CTCR_DINC(n)		(((n) & 0x3) << 2)
+#define STM32_MDMA_CTCR_SINC_MASK	GENMASK(1, 0)
+#define STM32_MDMA_CTCR_SINC(n)		((n) & STM32_MDMA_CTCR_SINC_MASK)
+#define STM32_MDMA_CTCR_CFG_MASK	(STM32_MDMA_CTCR_SINC_MASK \
+					| STM32_MDMA_CTCR_DINC_MASK \
+					| STM32_MDMA_CTCR_SINCOS_MASK \
+					| STM32_MDMA_CTCR_DINCOS_MASK \
+					| STM32_MDMA_CTCR_LEN2_MSK \
+					| STM32_MDMA_CTCR_TRGM_MSK)
+
+/* MDMA Channel x block number of data register */
+#define STM32_MDMA_CBNDTR(x)		(0x54 + 0x40 * (x))
+#define STM32_MDMA_CBNDTR_BRC_MK	GENMASK(31, 20)
+#define STM32_MDMA_CBNDTR_BRC(n)	(((n) & 0xfff) << 20)
+#define STM32_MDMA_CBNDTR_BRC_GET(n)	(((n) & STM32_MDMA_CBNDTR_BRC_MK) >> 20)
+#define STM32_MDMA_CBNDTR_BRDUM		BIT(19)
+#define STM32_MDMA_CBNDTR_BRSUM		BIT(18)
+#define STM32_MDMA_CBNDTR_BNDT_MASK	GENMASK(16, 0)
+#define STM32_MDMA_CBNDTR_BNDT(n)	((n) & STM32_MDMA_CBNDTR_BNDT_MASK)
+
+/* MDMA Channel x source address register */
+#define STM32_MDMA_CSAR(x)		(0x58 + 0x40 * (x))
+
+/* MDMA Channel x destination address register */
+#define STM32_MDMA_CDAR(x)		(0x5C + 0x40 * (x))
+
+/* MDMA Channel x block repeat address update register */
+#define STM32_MDMA_CBRUR(x)		(0x60 + 0x40 * (x))
+#define STM32_MDMA_CBRUR_DUV_MASK	GENMASK(31, 16)
+#define STM32_MDMA_CBRUR_DUV(n)		(((n) & 0xffff) << 16)
+#define STM32_MDMA_CBRUR_SUV_MASK	GENMASK(15, 0)
+#define STM32_MDMA_CBRUR_SUV(n)		((n) & STM32_MDMA_CBRUR_SUV_MASK)
+
+/* MDMA Channel x link address register */
+#define STM32_MDMA_CLAR(x)		(0x64 + 0x40 * (x))
+
+/* MDMA Channel x trigger and bus selection register */
+#define STM32_MDMA_CTBR(x)		(0x68 + 0x40 * (x))
+#define STM32_MDMA_CTBR_DBUS		BIT(17)
+#define STM32_MDMA_CTBR_SBUS		BIT(16)
+#define STM32_MDMA_CTBR_TSEL_MASK	GENMASK(7, 0)
+#define STM32_MDMA_CTBR_TSEL(n)	((n) & STM32_MDMA_CTBR_TSEL_MASK)
+
+/* MDMA Channel x mask address register */
+#define STM32_MDMA_CMAR(x)		(0x70 + 0x40 * (x))
+
+/* MDMA Channel x mask data register */
+#define STM32_MDMA_CMDR(x)		(0x74 + 0x40 * (x))
+
+#define STM32_MDMA_MAX_BUF_LEN		128
+#define STM32_MDMA_MAX_BLOCK_LEN	65536
+#define STM32_MDMA_MAX_CHANNELS		63
+#define STM32_MDMA_MAX_REQUESTS		256
+#define STM32_MDMA_MAX_BURST		128
+#define STM32_MDMA_VERY_HIGH_PRIORITY	0x11
+
+enum stm32_mdma_trigger_mode {
+	STM32_MDMA_BUFFER,
+	STM32_MDMA_BLOCK,
+	STM32_MDMA_BLOCK_REP,
+	STM32_MDMA_LINKED_LIST,
+};
+
+enum stm32_mdma_width {
+	STM32_MDMA_BYTE,
+	STM32_MDMA_HALF_WORD,
+	STM32_MDMA_WORD,
+	STM32_MDMA_DOUBLE_WORD,
+};
+
+enum stm32_mdma_inc_mode {
+	STM32_MDMA_FIXED = 0,
+	STM32_MDMA_INC = 2,
+	STM32_MDMA_DEC = 3,
+};
+
+struct stm32_mdma_chan_config {
+	u32 request;
+	u32 priority_level;
+	u32 transfer_config;
+	u32 mask_addr;
+	u32 mask_data;
+};
+
+struct stm32_mdma_hwdesc {
+	u32 ctcr;
+	u32 cbndtr;
+	u32 csar;
+	u32 cdar;
+	u32 cbrur;
+	u32 clar;
+	u32 ctbr;
+	u32 dummy;
+	u32 cmar;
+	u32 cmdr;
+} __aligned(64);
+
+struct stm32_mdma_desc {
+	struct virt_dma_desc vdesc;
+	u32 ccr;
+	struct stm32_mdma_hwdesc *hwdesc;
+	dma_addr_t hwdesc_phys;
+	bool cyclic;
+	u32 count;
+};
+
+struct stm32_mdma_chan {
+	struct virt_dma_chan vchan;
+	struct dma_pool *desc_pool;
+	u32 id;
+	struct stm32_mdma_desc *desc;
+	u32 curr_hwdesc;
+	struct dma_slave_config dma_config;
+	struct stm32_mdma_chan_config chan_config;
+	bool busy;
+	u32 mem_burst;
+	u32 mem_width;
+};
+
+struct stm32_mdma_device {
+	struct dma_device ddev;
+	void __iomem *base;
+	struct clk *clk;
+	u32 irq;
+	struct reset_control *rst;
+	u32 nr_channels;
+	u32 nr_requests;
+	u32 nr_ahb_addr_masks;
+	struct stm32_mdma_chan chan[STM32_MDMA_MAX_CHANNELS];
+	u32 ahb_addr_masks[];
+};
+
+static struct stm32_mdma_device *stm32_mdma_get_dev(
+	struct stm32_mdma_chan *chan)
+{
+	return container_of(chan->vchan.chan.device, struct stm32_mdma_device,
+			    ddev);
+}
+
+static struct stm32_mdma_chan *to_stm32_mdma_chan(struct dma_chan *c)
+{
+	return container_of(c, struct stm32_mdma_chan, vchan.chan);
+}
+
+static struct stm32_mdma_desc *to_stm32_mdma_desc(struct virt_dma_desc *vdesc)
+{
+	return container_of(vdesc, struct stm32_mdma_desc, vdesc);
+}
+
+static struct device *chan2dev(struct stm32_mdma_chan *chan)
+{
+	return &chan->vchan.chan.dev->device;
+}
+
+static struct device *mdma2dev(struct stm32_mdma_device *mdma_dev)
+{
+	return mdma_dev->ddev.dev;
+}
+
+static u32 stm32_mdma_read(struct stm32_mdma_device *dmadev, u32 reg)
+{
+	return readl_relaxed(dmadev->base + reg);
+}
+
+static void stm32_mdma_write(struct stm32_mdma_device *dmadev, u32 reg, u32 val)
+{
+	writel_relaxed(val, dmadev->base + reg);
+}
+
+static void stm32_mdma_set_bits(struct stm32_mdma_device *dmadev, u32 reg,
+				u32 mask)
+{
+	void __iomem *addr = dmadev->base + reg;
+
+	writel_relaxed(readl_relaxed(addr) | mask, addr);
+}
+
+static void stm32_mdma_clr_bits(struct stm32_mdma_device *dmadev, u32 reg,
+				u32 mask)
+{
+	void __iomem *addr = dmadev->base + reg;
+
+	writel_relaxed(readl_relaxed(addr) & ~mask, addr);
+}
+
+static struct stm32_mdma_desc *stm32_mdma_alloc_desc(
+		struct stm32_mdma_chan *chan, u32 count)
+{
+	struct stm32_mdma_desc *desc;
+
+	desc = kzalloc(sizeof(*desc), GFP_NOWAIT);
+	if (!desc)
+		return NULL;
+
+	desc->hwdesc = dma_pool_alloc(chan->desc_pool, GFP_NOWAIT,
+				       &desc->hwdesc_phys);
+	if (!desc->hwdesc) {
+		dev_err(chan2dev(chan), "Failed to allocate descriptor\n");
+		kfree(desc);
+		return NULL;
+	}
+
+	desc->count = count;
+
+	return desc;
+}
+
+static void stm32_mdma_desc_free(struct virt_dma_desc *vdesc)
+{
+	struct stm32_mdma_desc *desc = to_stm32_mdma_desc(vdesc);
+	struct stm32_mdma_chan *chan = to_stm32_mdma_chan(vdesc->tx.chan);
+
+	dma_pool_free(chan->desc_pool, desc->hwdesc, desc->hwdesc_phys);
+	kfree(desc);
+}
+
+static int stm32_mdma_get_width(struct stm32_mdma_chan *chan,
+				enum dma_slave_buswidth width)
+{
+	switch (width) {
+	case DMA_SLAVE_BUSWIDTH_1_BYTE:
+		return STM32_MDMA_BYTE;
+	case DMA_SLAVE_BUSWIDTH_2_BYTES:
+		return STM32_MDMA_HALF_WORD;
+	case DMA_SLAVE_BUSWIDTH_4_BYTES:
+		return STM32_MDMA_WORD;
+	case DMA_SLAVE_BUSWIDTH_8_BYTES:
+		return STM32_MDMA_DOUBLE_WORD;
+	default:
+		dev_err(chan2dev(chan), "Dma bus width not supported\n");
+		return -EINVAL;
+	}
+}
+
+static enum dma_slave_buswidth stm32_mdma_get_max_width(u32 buf_len, u32 tlen)
+{
+	enum dma_slave_buswidth max_width = DMA_SLAVE_BUSWIDTH_8_BYTES;
+
+	while ((buf_len <= max_width || buf_len % max_width ||
+		tlen < max_width) && max_width > DMA_SLAVE_BUSWIDTH_1_BYTE)
+		max_width = max_width >> 1;
+
+	return max_width;
+}
+
+static u32 stm32_mdma_get_best_burst(u32 buf_len, u32 tlen, u32 max_burst,
+				     enum dma_slave_buswidth width)
+{
+	u32 best_burst = max_burst;
+	u32 burst_len = best_burst * width;
+
+	if (buf_len % tlen)
+		return 0;
+
+	while ((tlen < burst_len && best_burst > 1) ||
+	       (burst_len > 0 && tlen % burst_len)) {
+		best_burst = best_burst >> 1;
+		burst_len = best_burst * width;
+	}
+
+	return (best_burst > 1) ? best_burst : 0;
+}
+
+static int stm32_mdma_disable_chan(struct stm32_mdma_chan *chan)
+{
+	struct stm32_mdma_device *dmadev = stm32_mdma_get_dev(chan);
+	u32 ccr, cisr, id, reg;
+	int ret;
+
+	id = chan->id;
+	reg = STM32_MDMA_CCR(id);
+
+	/* Disable interrupts */
+	stm32_mdma_clr_bits(dmadev, reg, STM32_MDMA_CCR_IRQ_MASK);
+
+	ccr = stm32_mdma_read(dmadev, reg);
+	if (ccr & STM32_MDMA_CCR_EN) {
+		stm32_mdma_clr_bits(dmadev, reg, STM32_MDMA_CCR_EN);
+
+		/* Ensure that any ongoing transfer has been completed */
+		ret = readl_relaxed_poll_timeout_atomic(
+				dmadev->base + STM32_MDMA_CISR(id), cisr,
+				(cisr & STM32_MDMA_CISR_CTCIF), 10, 1000);
+		if (ret) {
+			dev_err(chan2dev(chan), "%s: timeout!\n", __func__);
+			return -EBUSY;
+		}
+	}
+
+	return 0;
+}
+
+static void stm32_mdma_stop(struct stm32_mdma_chan *chan)
+{
+	struct stm32_mdma_device *dmadev = stm32_mdma_get_dev(chan);
+	u32 status;
+	int ret;
+
+	/* Disable DMA */
+	ret = stm32_mdma_disable_chan(chan);
+	if (ret < 0)
+		return;
+
+	/* Clear interrupt status if it is there */
+	status = stm32_mdma_read(dmadev, STM32_MDMA_CISR(chan->id));
+	if (status) {
+		dev_dbg(chan2dev(chan), "%s(): clearing interrupt: 0x%08x\n",
+			__func__, status);
+		stm32_mdma_set_bits(dmadev, STM32_MDMA_CIFCR(chan->id), status);
+	}
+
+	chan->busy = false;
+}
+
+static void stm32_mdma_set_dst_bus(struct stm32_mdma_device *dmadev, u32 *ctbr,
+				   u32 dst_addr)
+{
+	u32 mask;
+	int i;
+
+	/* Check if memory device is on AHB or AXI */
+	*ctbr &= ~STM32_MDMA_CTBR_DBUS;
+	mask = dst_addr & 0xF0000000;
+	for (i = 0; i < dmadev->nr_ahb_addr_masks; i++) {
+		if (mask == dmadev->ahb_addr_masks[i]) {
+			*ctbr |= STM32_MDMA_CTBR_DBUS;
+			break;
+		}
+	}
+}
+
+static void stm32_mdma_set_src_bus(struct stm32_mdma_device *dmadev, u32 *ctbr,
+				   u32 src_addr)
+{
+	u32 mask;
+	int i;
+
+	/* Check if memory device is on AHB or AXI */
+	*ctbr &= ~STM32_MDMA_CTBR_SBUS;
+	mask = src_addr & 0xF0000000;
+	for (i = 0; i < dmadev->nr_ahb_addr_masks; i++) {
+		if (mask == dmadev->ahb_addr_masks[i]) {
+			*ctbr |= STM32_MDMA_CTBR_SBUS;
+			break;
+		}
+	}
+}
+
+static int stm32_mdma_set_xfer_param(struct stm32_mdma_chan *chan,
+				     enum dma_transfer_direction direction,
+				     u32 *mdma_ccr, u32 *mdma_ctcr,
+				     u32 *mdma_ctbr, u32 buf_len)
+{
+	struct stm32_mdma_device *dmadev = stm32_mdma_get_dev(chan);
+	struct stm32_mdma_chan_config *chan_config = &chan->chan_config;
+	enum dma_slave_buswidth src_addr_width, dst_addr_width;
+	phys_addr_t src_addr, dst_addr;
+	int src_bus_width, dst_bus_width;
+	u32 src_maxburst, dst_maxburst, src_best_burst, dst_best_burst;
+	u32 ccr, ctcr, ctbr, tlen;
+
+	src_addr_width = chan->dma_config.src_addr_width;
+	dst_addr_width = chan->dma_config.dst_addr_width;
+	src_maxburst = chan->dma_config.src_maxburst;
+	dst_maxburst = chan->dma_config.dst_maxburst;
+	src_addr = chan->dma_config.src_addr;
+	dst_addr = chan->dma_config.dst_addr;
+
+	ccr = stm32_mdma_read(dmadev, STM32_MDMA_CCR(chan->id));
+	ctcr = stm32_mdma_read(dmadev, STM32_MDMA_CTCR(chan->id));
+	ctbr = stm32_mdma_read(dmadev, STM32_MDMA_CTBR(chan->id));
+
+	/* Enable HW request mode */
+	ctcr &= ~STM32_MDMA_CTCR_SWRM;
+
+	/* Set DINC, SINC, DINCOS, SINCOS, TRGM and TLEN retrieve from DT */
+	ctcr &= ~STM32_MDMA_CTCR_CFG_MASK;
+	ctcr |= chan_config->transfer_config & STM32_MDMA_CTCR_CFG_MASK;
+
+	/*
+	 * For buffer transfer length (TLEN) we have to set
+	 * the number of bytes - 1 in CTCR register
+	 */
+	tlen = STM32_MDMA_CTCR_LEN2_GET(ctcr);
+	ctcr &= ~STM32_MDMA_CTCR_LEN2_MSK;
+	ctcr |= STM32_MDMA_CTCR_TLEN((tlen - 1));
+
+	/* Check burst size constraints */
+	if (src_maxburst * src_addr_width > STM32_MDMA_MAX_BURST ||
+	    dst_maxburst * dst_addr_width > STM32_MDMA_MAX_BURST) {
+		dev_err(chan2dev(chan),
+			"burst size * bus width higher than %d bytes\n",
+			STM32_MDMA_MAX_BURST);
+		return -EINVAL;
+	}
+
+	if ((!is_power_of_2(src_maxburst) && src_maxburst > 0) ||
+	    (!is_power_of_2(dst_maxburst) && dst_maxburst > 0)) {
+		dev_err(chan2dev(chan), "burst size must be a power of 2\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * Configure channel control:
+	 * - Clear SW request as in this case this is a HW one
+	 * - Clear WEX, HEX and BEX bits
+	 * - Set priority level
+	 */
+	ccr &= ~(STM32_MDMA_CCR_SWRQ | STM32_MDMA_CCR_WEX | STM32_MDMA_CCR_HEX |
+		 STM32_MDMA_CCR_BEX | STM32_MDMA_CCR_PL_MASK);
+	ccr |= STM32_MDMA_CCR_PL(chan_config->priority_level);
+
+	/* Configure Trigger selection */
+	ctbr &= ~STM32_MDMA_CTBR_TSEL_MASK;
+	ctbr |= STM32_MDMA_CTBR_TSEL(chan_config->request);
+
+	switch (direction) {
+	case DMA_MEM_TO_DEV:
+		/* Set device data size */
+		dst_bus_width = stm32_mdma_get_width(chan, dst_addr_width);
+		if (dst_bus_width < 0)
+			return dst_bus_width;
+		ctcr &= ~STM32_MDMA_CTCR_DSIZE_MASK;
+		ctcr |= STM32_MDMA_CTCR_DSIZE(dst_bus_width);
+
+		/* Set device burst value */
+		dst_best_burst = stm32_mdma_get_best_burst(buf_len, tlen,
+							   dst_maxburst,
+							   dst_addr_width);
+		chan->mem_burst = dst_best_burst;
+		ctcr &= ~STM32_MDMA_CTCR_DBURST_MASK;
+		if (!dst_best_burst)
+			ctcr |= STM32_MDMA_CTCR_DBURST(dst_best_burst);
+		else
+			ctcr |= STM32_MDMA_CTCR_DBURST((ilog2(dst_best_burst)));
+
+		/* Set memory data size */
+		src_addr_width = stm32_mdma_get_max_width(buf_len, tlen);
+		chan->mem_width = src_addr_width;
+		src_bus_width = stm32_mdma_get_width(chan, src_addr_width);
+		if (src_bus_width < 0)
+			return src_bus_width;
+		ctcr &= ~STM32_MDMA_CTCR_SSIZE_MASK |
+			STM32_MDMA_CTCR_SINCOS_MASK;
+		ctcr |= STM32_MDMA_CTCR_SSIZE(src_bus_width) |
+			STM32_MDMA_CTCR_SINCOS(src_bus_width);
+
+		/* Set memory burst value */
+		src_maxburst = STM32_MDMA_MAX_BUF_LEN / src_addr_width;
+		src_best_burst = stm32_mdma_get_best_burst(buf_len, tlen,
+							   src_maxburst,
+							   src_addr_width);
+		chan->mem_burst = src_best_burst;
+		ctcr &= ~STM32_MDMA_CTCR_SBURST_MASK;
+		if (!src_best_burst)
+			ctcr |= STM32_MDMA_CTCR_SBURST(src_best_burst);
+		else
+			ctcr |= STM32_MDMA_CTCR_SBURST((ilog2(src_best_burst)));
+
+		/* Select bus */
+		stm32_mdma_set_dst_bus(dmadev, &ctbr, dst_addr);
+
+		/* Set destination address */
+		stm32_mdma_write(dmadev, STM32_MDMA_CDAR(chan->id), dst_addr);
+		break;
+
+	case DMA_DEV_TO_MEM:
+		/* Set device data size */
+		src_bus_width = stm32_mdma_get_width(chan, src_addr_width);
+		if (src_bus_width < 0)
+			return src_bus_width;
+		ctcr &= ~STM32_MDMA_CTCR_SSIZE_MASK;
+		ctcr |= STM32_MDMA_CTCR_SSIZE(src_bus_width);
+
+		/* Set device burst value */
+		src_best_burst = stm32_mdma_get_best_burst(buf_len, tlen,
+							   src_maxburst,
+							   src_addr_width);
+		ctcr &= ~STM32_MDMA_CTCR_SBURST_MASK;
+		if (!src_best_burst)
+			ctcr |= STM32_MDMA_CTCR_SBURST(src_best_burst);
+		else
+			ctcr |= STM32_MDMA_CTCR_SBURST((ilog2(src_best_burst)));
+
+		/* Set memory data size */
+		dst_addr_width = stm32_mdma_get_max_width(buf_len, tlen);
+		chan->mem_width = dst_addr_width;
+		dst_bus_width = stm32_mdma_get_width(chan, dst_addr_width);
+		if (dst_bus_width < 0)
+			return dst_bus_width;
+		ctcr &= ~(STM32_MDMA_CTCR_DSIZE_MASK |
+			STM32_MDMA_CTCR_DINCOS_MASK);
+		ctcr |= STM32_MDMA_CTCR_DSIZE(dst_bus_width) |
+			STM32_MDMA_CTCR_DINCOS(dst_bus_width);
+
+		/* Set memory burst value */
+		dst_maxburst = STM32_MDMA_MAX_BUF_LEN / dst_addr_width;
+		dst_best_burst = stm32_mdma_get_best_burst(buf_len, tlen,
+							   dst_maxburst,
+							   dst_addr_width);
+		ctcr &= ~STM32_MDMA_CTCR_DBURST_MASK;
+		if (!dst_best_burst)
+			ctcr |= STM32_MDMA_CTCR_DBURST(dst_best_burst);
+		else
+			ctcr |= STM32_MDMA_CTCR_DBURST((ilog2(dst_best_burst)));
+
+		/* Select bus */
+		stm32_mdma_set_src_bus(dmadev, &ctbr, src_addr);
+
+		/* Set source address */
+		stm32_mdma_write(dmadev, STM32_MDMA_CSAR(chan->id), src_addr);
+		break;
+
+	default:
+		dev_err(chan2dev(chan), "Dma direction is not supported\n");
+		return -EINVAL;
+	}
+
+	*mdma_ccr = ccr;
+	*mdma_ctcr = ctcr;
+	*mdma_ctbr = ctbr;
+
+	return 0;
+}
+
+static void stm32_mdma_dump_hwdesc(struct stm32_mdma_chan *chan,
+				   struct stm32_mdma_hwdesc *hwdesc)
+{
+	dev_dbg(chan2dev(chan), "hwdesc:  0x%08x\n", (unsigned int)hwdesc);
+	dev_dbg(chan2dev(chan), "CTCR:    0x%08x\n", hwdesc->ctcr);
+	dev_dbg(chan2dev(chan), "CBNDTR:  0x%08x\n", hwdesc->cbndtr);
+	dev_dbg(chan2dev(chan), "CSAR:    0x%08x\n", hwdesc->csar);
+	dev_dbg(chan2dev(chan), "CDAR:    0x%08x\n", hwdesc->cdar);
+	dev_dbg(chan2dev(chan), "CBRUR:   0x%08x\n", hwdesc->cbrur);
+	dev_dbg(chan2dev(chan), "CLAR:    0x%08x\n", hwdesc->clar);
+	dev_dbg(chan2dev(chan), "CTBR:    0x%08x\n", hwdesc->ctbr);
+	dev_dbg(chan2dev(chan), "CMAR:    0x%08x\n", hwdesc->cmar);
+	dev_dbg(chan2dev(chan), "CMDR:    0x%08x\n\n", hwdesc->cmdr);
+}
+
+static void stm32_mdma_setup_hwdesc(struct stm32_mdma_chan *chan,
+				    struct stm32_mdma_desc *desc,
+				    enum dma_transfer_direction dir, u32 count,
+				    dma_addr_t src_addr, dma_addr_t dst_addr,
+				    u32 len, u32 ctcr, u32 ctbr, bool is_last,
+				    bool is_first, bool is_cyclic)
+{
+	struct stm32_mdma_chan_config *config = &chan->chan_config;
+	struct stm32_mdma_hwdesc *hwdesc;
+	u32 next = count + 1;
+
+	hwdesc = &desc->hwdesc[count];
+	hwdesc->ctcr = ctcr;
+	hwdesc->cbndtr &= ~(STM32_MDMA_CBNDTR_BRC_MK |
+			STM32_MDMA_CBNDTR_BRDUM |
+			STM32_MDMA_CBNDTR_BRSUM |
+			STM32_MDMA_CBNDTR_BNDT_MASK);
+	hwdesc->cbndtr |= STM32_MDMA_CBNDTR_BNDT(len);
+	hwdesc->csar = src_addr;
+	hwdesc->cdar = dst_addr;
+	hwdesc->cbrur = 0;
+	hwdesc->clar = desc->hwdesc_phys + next * sizeof(*hwdesc);
+	hwdesc->ctbr = ctbr;
+	hwdesc->cmar = config->mask_addr;
+	hwdesc->cmdr = config->mask_data;
+
+	if (is_last) {
+		if (is_cyclic)
+			hwdesc->clar = desc->hwdesc_phys;
+		else
+			hwdesc->clar = 0;
+	}
+
+	stm32_mdma_dump_hwdesc(chan, hwdesc);
+}
+
+static int stm32_mdma_setup_xfer(struct stm32_mdma_chan *chan,
+				 struct stm32_mdma_desc *desc,
+				 struct scatterlist *sgl, u32 sg_len,
+				 enum dma_transfer_direction direction)
+{
+	struct stm32_mdma_device *dmadev = stm32_mdma_get_dev(chan);
+	struct dma_slave_config *dma_config = &chan->dma_config;
+	struct scatterlist *sg;
+	dma_addr_t src_addr, dst_addr;
+	u32 ccr, ctcr, ctbr;
+	int i, ret = 0;
+
+	for_each_sg(sgl, sg, sg_len, i) {
+		if (sg_dma_len(sg) > STM32_MDMA_MAX_BLOCK_LEN) {
+			dev_err(chan2dev(chan), "Invalid block len\n");
+			return -EINVAL;
+		}
+
+		ret = stm32_mdma_set_xfer_param(chan, direction, &ccr, &ctcr,
+						&ctbr, sg_dma_len(sg));
+		if (ret < 0)
+			return ret;
+
+		if (direction == DMA_MEM_TO_DEV) {
+			src_addr = sg_dma_address(sg);
+			dst_addr = dma_config->dst_addr;
+			stm32_mdma_set_src_bus(dmadev, &ctbr, src_addr);
+		} else {
+			src_addr = dma_config->src_addr;
+			dst_addr = sg_dma_address(sg);
+			stm32_mdma_set_dst_bus(dmadev, &ctbr, dst_addr);
+		}
+
+		stm32_mdma_setup_hwdesc(chan, desc, direction, i, src_addr,
+					dst_addr, sg_dma_len(sg), ctcr, ctbr,
+					i == sg_len - 1, i == 0, false);
+	}
+
+	/* Enable interrupts */
+	ccr &= ~STM32_MDMA_CCR_IRQ_MASK;
+	ccr |= STM32_MDMA_CCR_TEIE | STM32_MDMA_CCR_CTCIE;
+	if (sg_len > 1)
+		ccr |= STM32_MDMA_CCR_BTIE;
+	desc->ccr = ccr;
+
+	return 0;
+}
+
+static struct dma_async_tx_descriptor *stm32_mdma_prep_slave_sg(
+	struct dma_chan *c, struct scatterlist *sgl,
+	u32 sg_len, enum dma_transfer_direction direction,
+	unsigned long flags, void *context)
+{
+	struct stm32_mdma_chan *chan = to_stm32_mdma_chan(c);
+	struct stm32_mdma_desc *desc;
+	int ret;
+
+	desc = stm32_mdma_alloc_desc(chan, sg_len);
+	if (!desc)
+		return NULL;
+
+	ret = stm32_mdma_setup_xfer(chan, desc, sgl, sg_len, direction);
+	if (ret < 0)
+		goto xfer_setup_err;
+
+	desc->cyclic = false;
+
+	return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
+
+xfer_setup_err:
+	dma_pool_free(chan->desc_pool, &desc->hwdesc, desc->hwdesc_phys);
+	kfree(desc);
+	return NULL;
+}
+
+static struct dma_async_tx_descriptor *stm32_mdma_prep_dma_cyclic(
+	struct dma_chan *c, dma_addr_t buf_addr, size_t buf_len,
+	size_t period_len, enum dma_transfer_direction direction,
+	unsigned long flags)
+{
+	struct stm32_mdma_chan *chan = to_stm32_mdma_chan(c);
+	struct stm32_mdma_device *dmadev = stm32_mdma_get_dev(chan);
+	struct dma_slave_config *dma_config = &chan->dma_config;
+	struct stm32_mdma_desc *desc;
+	dma_addr_t src_addr, dst_addr;
+	u32 ccr, ctcr, ctbr, count;
+	int i, ret;
+
+	if (!buf_len || !period_len || period_len > STM32_MDMA_MAX_BLOCK_LEN) {
+		dev_err(chan2dev(chan), "Invalid buffer/period len\n");
+		return NULL;
+	}
+
+	if (buf_len % period_len) {
+		dev_err(chan2dev(chan), "buf_len not multiple of period_len\n");
+		return NULL;
+	}
+
+	/*
+	 * We allow to take more number of requests till DMA is
+	 * not started. The driver will loop over all requests.
+	 * Once DMA is started then new requests can be queued only after
+	 * terminating the DMA.
+	 */
+	if (chan->busy) {
+		dev_err(chan2dev(chan), "Request not allowed when dma busy\n");
+		return NULL;
+	}
+
+	count = buf_len / period_len;
+
+	desc = stm32_mdma_alloc_desc(chan, count);
+	if (!desc)
+		return NULL;
+
+	ret = stm32_mdma_set_xfer_param(chan, direction, &ccr, &ctcr, &ctbr,
+					period_len);
+	if (ret < 0)
+		goto xfer_setup_err;
+
+	/* Enable interrupts */
+	ccr &= ~STM32_MDMA_CCR_IRQ_MASK;
+	ccr |= STM32_MDMA_CCR_TEIE | STM32_MDMA_CCR_CTCIE | STM32_MDMA_CCR_BTIE;
+	desc->ccr = ccr;
+
+	/* Select bus */
+	if (direction == DMA_MEM_TO_DEV) {
+		src_addr = buf_addr;
+		stm32_mdma_set_src_bus(dmadev, &ctbr, src_addr);
+	} else {
+		dst_addr = buf_addr;
+		stm32_mdma_set_dst_bus(dmadev, &ctbr, dst_addr);
+	}
+
+	/* Configure hwdesc list */
+	for (i = 0; i < count; i++) {
+		if (direction == DMA_MEM_TO_DEV) {
+			src_addr = buf_addr + i * period_len;
+			dst_addr = dma_config->dst_addr;
+		} else {
+			src_addr = dma_config->src_addr;
+			dst_addr = buf_addr + i * period_len;
+		}
+
+		stm32_mdma_setup_hwdesc(chan, desc, direction, i, src_addr,
+					dst_addr, period_len, ctcr, ctbr,
+					i == count - 1, i == 0, true);
+	}
+
+	desc->cyclic = true;
+
+	return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
+
+xfer_setup_err:
+	dma_pool_free(chan->desc_pool, &desc->hwdesc, desc->hwdesc_phys);
+	kfree(desc);
+	return NULL;
+}
+
+static struct dma_async_tx_descriptor *stm32_mdma_prep_dma_memcpy(
+	struct dma_chan *c, dma_addr_t dest,
+	dma_addr_t src, size_t len, unsigned long flags)
+{
+	struct stm32_mdma_chan *chan = to_stm32_mdma_chan(c);
+	struct stm32_mdma_device *dmadev = stm32_mdma_get_dev(chan);
+	enum dma_slave_buswidth max_width;
+	struct stm32_mdma_desc *desc;
+	struct stm32_mdma_hwdesc *hwdesc;
+	u32 ccr, ctcr, ctbr, cbndtr, count, max_burst, mdma_burst;
+	u32 best_burst, tlen;
+	size_t xfer_count, offset;
+	int i;
+
+	count = DIV_ROUND_UP(len, STM32_MDMA_MAX_BLOCK_LEN);
+	desc = stm32_mdma_alloc_desc(chan, count);
+	if (!desc)
+		return NULL;
+
+	ccr = stm32_mdma_read(dmadev, STM32_MDMA_CCR(chan->id));
+	ctcr = stm32_mdma_read(dmadev, STM32_MDMA_CTCR(chan->id));
+	ctbr = stm32_mdma_read(dmadev, STM32_MDMA_CTBR(chan->id));
+	cbndtr = stm32_mdma_read(dmadev, STM32_MDMA_CBNDTR(chan->id));
+
+	/* Enable sw req, some interrupts and clear other bits */
+	ccr &= ~(STM32_MDMA_CCR_WEX | STM32_MDMA_CCR_HEX |
+		 STM32_MDMA_CCR_BEX | STM32_MDMA_CCR_PL_MASK |
+		 STM32_MDMA_CCR_IRQ_MASK);
+	ccr |= STM32_MDMA_CCR_TEIE;
+
+	/* Enable SW request mode, dest/src inc and clear other bits */
+	ctcr &= ~(STM32_MDMA_CTCR_BWM | STM32_MDMA_CTCR_TRGM_MSK |
+		  STM32_MDMA_CTCR_PAM_MASK | STM32_MDMA_CTCR_PKE |
+		  STM32_MDMA_CTCR_TLEN_MSK | STM32_MDMA_CTCR_DBURST_MASK |
+		  STM32_MDMA_CTCR_SBURST_MASK | STM32_MDMA_CTCR_DINCOS_MASK |
+		  STM32_MDMA_CTCR_SINCOS_MASK | STM32_MDMA_CTCR_DSIZE_MASK |
+		  STM32_MDMA_CTCR_SSIZE_MASK | STM32_MDMA_CTCR_DINC_MASK |
+		  STM32_MDMA_CTCR_SINC_MASK);
+	ctcr |= STM32_MDMA_CTCR_SWRM | STM32_MDMA_CTCR_SINC(STM32_MDMA_INC) |
+		STM32_MDMA_CTCR_DINC(STM32_MDMA_INC);
+
+	/* Reset HW request */
+	ctbr &= ~STM32_MDMA_CTBR_TSEL_MASK;
+
+	/* Select bus */
+	stm32_mdma_set_src_bus(dmadev, &ctbr, src);
+	stm32_mdma_set_dst_bus(dmadev, &ctbr, dest);
+
+	/* Clear CBNDTR registers */
+	cbndtr &= ~(STM32_MDMA_CBNDTR_BRC_MK | STM32_MDMA_CBNDTR_BRDUM |
+			STM32_MDMA_CBNDTR_BRSUM | STM32_MDMA_CBNDTR_BNDT_MASK);
+
+	if (len <= STM32_MDMA_MAX_BLOCK_LEN) {
+		cbndtr |= STM32_MDMA_CBNDTR_BNDT(len);
+		if (len <= STM32_MDMA_MAX_BUF_LEN) {
+			/* Setup a buffer transfer */
+			tlen = len - 1;
+			ccr |= STM32_MDMA_CCR_TCIE | STM32_MDMA_CCR_CTCIE;
+			ctcr |= STM32_MDMA_CTCR_TRGM(STM32_MDMA_BUFFER);
+			ctcr |= STM32_MDMA_CTCR_TLEN((tlen));
+		} else {
+			/* Setup a block transfer */
+			tlen = STM32_MDMA_MAX_BUF_LEN - 1;
+			ccr |= STM32_MDMA_CCR_BTIE | STM32_MDMA_CCR_CTCIE;
+			ctcr |= STM32_MDMA_CTCR_TRGM(STM32_MDMA_BLOCK);
+			ctcr |= STM32_MDMA_CTCR_TLEN(tlen);
+		}
+
+		/* Set best burst size */
+		max_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+		max_burst = (tlen + 1) / max_width;
+		best_burst = stm32_mdma_get_best_burst(len, tlen, max_burst,
+						       max_width);
+		if (!best_burst)
+			mdma_burst = best_burst;
+		else
+			mdma_burst = ilog2(best_burst);
+
+		ctcr |= STM32_MDMA_CTCR_DBURST(mdma_burst) |
+			STM32_MDMA_CTCR_SBURST(mdma_burst);
+
+		/* Prepare hardware descriptor */
+		hwdesc = desc->hwdesc;
+		hwdesc->ctcr = ctcr;
+		hwdesc->cbndtr = cbndtr;
+		hwdesc->csar = src;
+		hwdesc->cdar = dest;
+		hwdesc->cbrur = 0;
+		hwdesc->clar = 0;
+		hwdesc->ctbr = ctbr;
+		hwdesc->cmar = 0;
+		hwdesc->cmdr = 0;
+
+		stm32_mdma_dump_hwdesc(chan, hwdesc);
+	} else {
+		/* Setup a LLI transfer */
+		ctcr |= STM32_MDMA_CTCR_TRGM(STM32_MDMA_LINKED_LIST) |
+			STM32_MDMA_CTCR_TLEN((STM32_MDMA_MAX_BUF_LEN - 1));
+		ccr |= STM32_MDMA_CCR_BTIE | STM32_MDMA_CCR_CTCIE;
+
+		for (i = 0, offset = 0; offset < len;
+		     i++, offset += xfer_count) {
+			xfer_count = min_t(size_t, len - offset,
+					   STM32_MDMA_MAX_BLOCK_LEN);
+
+			/* Set best burst size */
+			max_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+			max_burst = STM32_MDMA_MAX_BUF_LEN / max_width;
+			best_burst = stm32_mdma_get_best_burst(xfer_count, tlen,
+							       max_burst,
+							       max_width);
+			if (!best_burst)
+				mdma_burst = best_burst;
+			else
+				mdma_burst = ilog2(best_burst);
+
+			ctcr &= ~(STM32_MDMA_CTCR_DBURST_MASK |
+				  STM32_MDMA_CTCR_SBURST_MASK);
+			ctcr |= STM32_MDMA_CTCR_DBURST(mdma_burst) |
+				STM32_MDMA_CTCR_SBURST(mdma_burst);
+
+			/* Prepare hardware descriptor */
+			stm32_mdma_setup_hwdesc(chan, desc, DMA_MEM_TO_MEM, i,
+						src + offset, dest + offset,
+						xfer_count, ctcr, ctbr,
+						i == count - 1, i == 0, false);
+		}
+	}
+
+	desc->ccr = ccr;
+
+	desc->cyclic = false;
+
+	return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
+}
+
+static void stm32_mdma_dump_reg(struct stm32_mdma_chan *chan)
+{
+	struct stm32_mdma_device *dmadev = stm32_mdma_get_dev(chan);
+
+	dev_dbg(chan2dev(chan), "CCR:     0x%08x\n",
+		stm32_mdma_read(dmadev, STM32_MDMA_CCR(chan->id)));
+	dev_dbg(chan2dev(chan), "CTCR:    0x%08x\n",
+		stm32_mdma_read(dmadev, STM32_MDMA_CTCR(chan->id)));
+	dev_dbg(chan2dev(chan), "CBNDTR:  0x%08x\n",
+		stm32_mdma_read(dmadev, STM32_MDMA_CBNDTR(chan->id)));
+	dev_dbg(chan2dev(chan), "CSAR:    0x%08x\n",
+		stm32_mdma_read(dmadev, STM32_MDMA_CSAR(chan->id)));
+	dev_dbg(chan2dev(chan), "CDAR:    0x%08x\n",
+		stm32_mdma_read(dmadev, STM32_MDMA_CDAR(chan->id)));
+	dev_dbg(chan2dev(chan), "CBRUR:   0x%08x\n",
+		stm32_mdma_read(dmadev, STM32_MDMA_CBRUR(chan->id)));
+	dev_dbg(chan2dev(chan), "CLAR:    0x%08x\n",
+		stm32_mdma_read(dmadev, STM32_MDMA_CLAR(chan->id)));
+	dev_dbg(chan2dev(chan), "CTBR:    0x%08x\n",
+		stm32_mdma_read(dmadev, STM32_MDMA_CTBR(chan->id)));
+	dev_dbg(chan2dev(chan), "CMAR:    0x%08x\n",
+		stm32_mdma_read(dmadev, STM32_MDMA_CMAR(chan->id)));
+	dev_dbg(chan2dev(chan), "CMDR:    0x%08x\n",
+		stm32_mdma_read(dmadev, STM32_MDMA_CMDR(chan->id)));
+}
+
+static void stm32_mdma_start_transfer(struct stm32_mdma_chan *chan)
+{
+	struct stm32_mdma_device *dmadev = stm32_mdma_get_dev(chan);
+	struct virt_dma_desc *vdesc;
+	struct stm32_mdma_hwdesc *hwdesc;
+	u32 id = chan->id;
+	u32 status, reg;
+
+	vdesc = vchan_next_desc(&chan->vchan);
+	if (!vdesc) {
+		chan->desc = NULL;
+		return;
+	}
+
+	chan->desc = to_stm32_mdma_desc(vdesc);
+	hwdesc = chan->desc->hwdesc;
+	chan->curr_hwdesc = 0;
+
+	stm32_mdma_write(dmadev, STM32_MDMA_CCR(id), chan->desc->ccr);
+	stm32_mdma_write(dmadev, STM32_MDMA_CTCR(id), hwdesc->ctcr);
+	stm32_mdma_write(dmadev, STM32_MDMA_CBNDTR(id), hwdesc->cbndtr);
+	stm32_mdma_write(dmadev, STM32_MDMA_CSAR(id), hwdesc->csar);
+	stm32_mdma_write(dmadev, STM32_MDMA_CDAR(id), hwdesc->cdar);
+	stm32_mdma_write(dmadev, STM32_MDMA_CBRUR(id), hwdesc->cbrur);
+	stm32_mdma_write(dmadev, STM32_MDMA_CLAR(id), hwdesc->clar);
+	stm32_mdma_write(dmadev, STM32_MDMA_CTBR(id), hwdesc->ctbr);
+	stm32_mdma_write(dmadev, STM32_MDMA_CMAR(id), hwdesc->cmar);
+	stm32_mdma_write(dmadev, STM32_MDMA_CMDR(id), hwdesc->cmdr);
+
+	/* Clear interrupt status if it is there */
+	status = stm32_mdma_read(dmadev, STM32_MDMA_CISR(id));
+	if (status)
+		stm32_mdma_set_bits(dmadev, STM32_MDMA_CIFCR(id), status);
+
+	stm32_mdma_dump_reg(chan);
+
+	/* Start DMA */
+	stm32_mdma_set_bits(dmadev, STM32_MDMA_CCR(id), STM32_MDMA_CCR_EN);
+
+	/* Set SW request in case of MEM2MEM transfer */
+	if (hwdesc->ctcr & STM32_MDMA_CTCR_SWRM) {
+		reg = STM32_MDMA_CCR(id);
+		stm32_mdma_set_bits(dmadev, reg, STM32_MDMA_CCR_SWRQ);
+	}
+
+	chan->busy = true;
+
+	dev_dbg(chan2dev(chan), "vchan %p: started\n", &chan->vchan);
+}
+
+static void stm32_mdma_issue_pending(struct dma_chan *c)
+{
+	struct stm32_mdma_chan *chan = to_stm32_mdma_chan(c);
+	unsigned long flags;
+
+	spin_lock_irqsave(&chan->vchan.lock, flags);
+
+	if (!vchan_issue_pending(&chan->vchan))
+		goto end;
+
+	dev_dbg(chan2dev(chan), "vchan %p: issued\n", &chan->vchan);
+
+	if (!chan->desc && !chan->busy)
+		stm32_mdma_start_transfer(chan);
+
+end:
+	spin_unlock_irqrestore(&chan->vchan.lock, flags);
+}
+
+static int stm32_mdma_pause(struct dma_chan *c)
+{
+	struct stm32_mdma_chan *chan = to_stm32_mdma_chan(c);
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&chan->vchan.lock, flags);
+	ret = stm32_mdma_disable_chan(chan);
+	spin_unlock_irqrestore(&chan->vchan.lock, flags);
+
+	if (!ret)
+		dev_dbg(chan2dev(chan), "vchan %p: pause\n", &chan->vchan);
+
+	return ret;
+}
+
+static int stm32_mdma_resume(struct dma_chan *c)
+{
+	struct stm32_mdma_chan *chan = to_stm32_mdma_chan(c);
+	struct stm32_mdma_device *dmadev = stm32_mdma_get_dev(chan);
+	struct stm32_mdma_hwdesc *hwdesc;
+	unsigned long flags;
+	u32 status, reg;
+
+	hwdesc = &chan->desc->hwdesc[chan->curr_hwdesc];
+
+	spin_lock_irqsave(&chan->vchan.lock, flags);
+
+	/* Re-configure control register */
+	stm32_mdma_write(dmadev, STM32_MDMA_CCR(chan->id), chan->desc->ccr);
+
+	/* Clear interrupt status if it is there */
+	status = stm32_mdma_read(dmadev, STM32_MDMA_CISR(chan->id));
+	if (status)
+		stm32_mdma_set_bits(dmadev, STM32_MDMA_CIFCR(chan->id), status);
+
+	stm32_mdma_dump_reg(chan);
+
+	/* Re-start DMA */
+	reg = STM32_MDMA_CCR(chan->id);
+	stm32_mdma_set_bits(dmadev, reg, STM32_MDMA_CCR_EN);
+
+	/* Set SW request in case of MEM2MEM transfer */
+	if (hwdesc->ctcr & STM32_MDMA_CTCR_SWRM)
+		stm32_mdma_set_bits(dmadev, reg, STM32_MDMA_CCR_SWRQ);
+
+	spin_unlock_irqrestore(&chan->vchan.lock, flags);
+
+	dev_dbg(chan2dev(chan), "vchan %p: resume\n", &chan->vchan);
+
+	return 0;
+}
+
+static int stm32_mdma_terminate_all(struct dma_chan *c)
+{
+	struct stm32_mdma_chan *chan = to_stm32_mdma_chan(c);
+	unsigned long flags;
+	LIST_HEAD(head);
+
+	spin_lock_irqsave(&chan->vchan.lock, flags);
+	if (chan->busy) {
+		stm32_mdma_stop(chan);
+		chan->desc = NULL;
+	}
+	vchan_get_all_descriptors(&chan->vchan, &head);
+	spin_unlock_irqrestore(&chan->vchan.lock, flags);
+
+	vchan_dma_desc_free_list(&chan->vchan, &head);
+
+	return 0;
+}
+
+static void stm32_mdma_synchronize(struct dma_chan *c)
+{
+	struct stm32_mdma_chan *chan = to_stm32_mdma_chan(c);
+
+	vchan_synchronize(&chan->vchan);
+}
+
+static int stm32_mdma_slave_config(struct dma_chan *c,
+				   struct dma_slave_config *config)
+{
+	struct stm32_mdma_chan *chan = to_stm32_mdma_chan(c);
+
+	memcpy(&chan->dma_config, config, sizeof(*config));
+
+	return 0;
+}
+
+static size_t stm32_mdma_desc_residue(struct stm32_mdma_chan *chan,
+				      struct stm32_mdma_desc *desc,
+				      u32 curr_hwdesc)
+{
+	struct stm32_mdma_device *dmadev = stm32_mdma_get_dev(chan);
+	struct stm32_mdma_hwdesc *hwdesc = desc->hwdesc;
+	u32 cbndtr, residue, modulo, burst_size;
+	int i;
+
+	residue = 0;
+	for (i = curr_hwdesc + 1; i < desc->count; i++) {
+		hwdesc = &desc->hwdesc[i];
+		residue += STM32_MDMA_CBNDTR_BNDT(hwdesc->cbndtr);
+	}
+	cbndtr = stm32_mdma_read(dmadev, STM32_MDMA_CBNDTR(chan->id));
+	residue += cbndtr & STM32_MDMA_CBNDTR_BNDT_MASK;
+
+	if (!chan->mem_burst)
+		return residue;
+
+	burst_size = chan->mem_burst * chan->mem_width;
+	modulo = residue % burst_size;
+	if (modulo)
+		residue = residue - modulo + burst_size;
+
+	return residue;
+}
+
+static enum dma_status stm32_mdma_tx_status(struct dma_chan *c,
+					    dma_cookie_t cookie,
+					    struct dma_tx_state *state)
+{
+	struct stm32_mdma_chan *chan = to_stm32_mdma_chan(c);
+	struct virt_dma_desc *vdesc;
+	enum dma_status status;
+	unsigned long flags;
+	u32 residue = 0;
+
+	status = dma_cookie_status(c, cookie, state);
+	if ((status == DMA_COMPLETE) || (!state))
+		return status;
+
+	spin_lock_irqsave(&chan->vchan.lock, flags);
+
+	vdesc = vchan_find_desc(&chan->vchan, cookie);
+	if (chan->desc && cookie == chan->desc->vdesc.tx.cookie)
+		residue = stm32_mdma_desc_residue(chan, chan->desc,
+						  chan->curr_hwdesc);
+	else if (vdesc)
+		residue = stm32_mdma_desc_residue(chan,
+						  to_stm32_mdma_desc(vdesc), 0);
+	dma_set_residue(state, residue);
+
+	spin_unlock_irqrestore(&chan->vchan.lock, flags);
+
+	return status;
+}
+
+static void stm32_mdma_xfer_end(struct stm32_mdma_chan *chan)
+{
+	list_del(&chan->desc->vdesc.node);
+	vchan_cookie_complete(&chan->desc->vdesc);
+	chan->desc = NULL;
+	chan->busy = false;
+
+	/* Start the next transfer if this driver has a next desc */
+	stm32_mdma_start_transfer(chan);
+}
+
+static irqreturn_t stm32_mdma_irq_handler(int irq, void *devid)
+{
+	struct stm32_mdma_device *dmadev = devid;
+	struct stm32_mdma_chan *chan = devid;
+	u32 reg, id, ien, status, flag;
+
+	/* Find out which channel generates the interrupt */
+	status = readl_relaxed(dmadev->base + STM32_MDMA_GISR0);
+	if (status) {
+		id = __ffs(status);
+	} else {
+		status = readl_relaxed(dmadev->base + STM32_MDMA_GISR1);
+		if (!status) {
+			dev_dbg(mdma2dev(dmadev), "spurious it\n");
+			return IRQ_NONE;
+		}
+		id = __ffs(status);
+		/*
+		 * As GISR0 provides status for channel id from 0 to 31,
+		 * so GISR1 provides status for channel id from 32 to 62
+		 */
+		id += 32;
+	}
+
+	chan = &dmadev->chan[id];
+	if (!chan) {
+		dev_err(chan2dev(chan), "MDMA channel not initialized\n");
+		goto exit;
+	}
+
+	/* Handle interrupt for the channel */
+	spin_lock(&chan->vchan.lock);
+	status = stm32_mdma_read(dmadev, STM32_MDMA_CISR(chan->id));
+	ien = stm32_mdma_read(dmadev, STM32_MDMA_CCR(chan->id));
+	ien &= STM32_MDMA_CCR_IRQ_MASK;
+	ien >>= 1;
+
+	if (!(status & ien)) {
+		dev_dbg(chan2dev(chan),
+			"spurious it (status=0x%04x, ien=0x%04x)\n",
+			status, ien);
+		return IRQ_NONE;
+	}
+
+	flag = __ffs(status & ien);
+	reg = STM32_MDMA_CIFCR(chan->id);
+
+	switch (1 << flag) {
+	case STM32_MDMA_CISR_TEIF:
+		id = chan->id;
+		status = readl_relaxed(dmadev->base + STM32_MDMA_CESR(id));
+		dev_err(chan2dev(chan), "Transfer Err: stat=0x%08x\n", status);
+		stm32_mdma_set_bits(dmadev, reg, STM32_MDMA_CIFCR_CTEIF);
+		break;
+
+	case STM32_MDMA_CISR_CTCIF:
+		stm32_mdma_set_bits(dmadev, reg, STM32_MDMA_CIFCR_CCTCIF);
+		stm32_mdma_xfer_end(chan);
+		break;
+
+	case STM32_MDMA_CISR_BRTIF:
+		stm32_mdma_set_bits(dmadev, reg, STM32_MDMA_CIFCR_CBRTIF);
+		break;
+
+	case STM32_MDMA_CISR_BTIF:
+		stm32_mdma_set_bits(dmadev, reg, STM32_MDMA_CIFCR_CBTIF);
+		chan->curr_hwdesc++;
+		if (chan->desc && chan->desc->cyclic) {
+			if (chan->curr_hwdesc == chan->desc->count)
+				chan->curr_hwdesc = 0;
+			vchan_cyclic_callback(&chan->desc->vdesc);
+		}
+		break;
+
+	case STM32_MDMA_CISR_TCIF:
+		stm32_mdma_set_bits(dmadev, reg, STM32_MDMA_CIFCR_CLTCIF);
+		break;
+
+	default:
+		dev_err(chan2dev(chan), "it %d unhandled (status=0x%04x)\n",
+			1 << flag, status);
+	}
+
+	spin_unlock(&chan->vchan.lock);
+
+exit:
+	return IRQ_HANDLED;
+}
+
+static int stm32_mdma_alloc_chan_resources(struct dma_chan *c)
+{
+	struct stm32_mdma_chan *chan = to_stm32_mdma_chan(c);
+	struct stm32_mdma_device *dmadev = stm32_mdma_get_dev(chan);
+	int ret;
+
+	chan->desc_pool = dmam_pool_create(dev_name(&c->dev->device),
+					  c->device->dev,
+					  sizeof(struct stm32_mdma_hwdesc),
+					  __alignof__(struct stm32_mdma_hwdesc),
+					  0);
+	if (!chan->desc_pool) {
+		dev_err(chan2dev(chan), "failed to allocate descriptor pool\n");
+		return -ENOMEM;
+	}
+
+	ret = clk_prepare_enable(dmadev->clk);
+	if (ret < 0) {
+		dev_err(chan2dev(chan), "clk_prepare_enable failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = stm32_mdma_disable_chan(chan);
+	if (ret < 0)
+		clk_disable_unprepare(dmadev->clk);
+
+	return ret;
+}
+
+static void stm32_mdma_free_chan_resources(struct dma_chan *c)
+{
+	struct stm32_mdma_chan *chan = to_stm32_mdma_chan(c);
+	struct stm32_mdma_device *dmadev = stm32_mdma_get_dev(chan);
+	unsigned long flags;
+
+	dev_dbg(chan2dev(chan), "Freeing channel %d\n", chan->id);
+
+	if (chan->busy) {
+		spin_lock_irqsave(&chan->vchan.lock, flags);
+		stm32_mdma_stop(chan);
+		chan->desc = NULL;
+		spin_unlock_irqrestore(&chan->vchan.lock, flags);
+	}
+
+	clk_disable_unprepare(dmadev->clk);
+	vchan_free_chan_resources(to_virt_chan(c));
+	dmam_pool_destroy(chan->desc_pool);
+	chan->desc_pool = NULL;
+}
+
+static struct dma_chan *stm32_mdma_of_xlate(struct of_phandle_args *dma_spec,
+					    struct of_dma *ofdma)
+{
+	struct stm32_mdma_device *dmadev = ofdma->of_dma_data;
+	struct stm32_mdma_chan *chan;
+	struct dma_chan *c;
+	struct stm32_mdma_chan_config config;
+
+	if (dma_spec->args_count < 5) {
+		dev_err(mdma2dev(dmadev), "Bad number of args\n");
+		return NULL;
+	}
+
+	config.request = dma_spec->args[0];
+	config.priority_level = dma_spec->args[1];
+	config.transfer_config = dma_spec->args[2];
+	config.mask_addr = dma_spec->args[3];
+	config.mask_data = dma_spec->args[4];
+
+	if (config.request >= dmadev->nr_requests) {
+		dev_err(mdma2dev(dmadev), "Bad request line\n");
+		return NULL;
+	}
+
+	if (config.priority_level > STM32_MDMA_VERY_HIGH_PRIORITY) {
+		dev_err(mdma2dev(dmadev), "Priority level not supported\n");
+		return NULL;
+	}
+
+	c = dma_get_any_slave_channel(&dmadev->ddev);
+	if (!c) {
+		dev_err(mdma2dev(dmadev), "No more channel avalaible\n");
+		return NULL;
+	}
+
+	chan = to_stm32_mdma_chan(c);
+	chan->chan_config = config;
+
+	return c;
+}
+
+static const struct of_device_id stm32_mdma_of_match[] = {
+	{ .compatible = "st,stm32-mdma", },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, stm32_mdma_of_match);
+
+static int stm32_mdma_probe(struct platform_device *pdev)
+{
+	struct stm32_mdma_chan *chan;
+	struct stm32_mdma_device *dmadev;
+	struct dma_device *dd;
+	struct device_node *of_node;
+	struct resource *res;
+	u32 nr_channels, nr_requests;
+	int i, count, ret;
+
+	of_node = pdev->dev.of_node;
+	if (!of_node)
+		return -ENODEV;
+
+	ret = of_property_read_u32(of_node, "dma-channels", &nr_channels);
+	if (ret)
+		nr_channels = STM32_MDMA_MAX_CHANNELS;
+
+	ret = of_property_read_u32(of_node, "dma-requests", &nr_requests);
+	if (ret)
+		nr_requests = STM32_MDMA_MAX_REQUESTS;
+
+	count = of_property_count_u32_elems(of_node, "st,ahb-addr-masks");
+	if (count < 0)
+		count = 0;
+
+	dmadev = devm_kzalloc(&pdev->dev, sizeof(*dmadev) + sizeof(u32) * count,
+			      GFP_KERNEL);
+	if (!dmadev)
+		return -ENOMEM;
+
+	dmadev->nr_channels = nr_channels;
+	dmadev->nr_requests = nr_requests;
+	of_property_read_u32_array(of_node, "st,ahb-addr-masks",
+				   dmadev->ahb_addr_masks,
+				   count);
+	dmadev->nr_ahb_addr_masks = count;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	dmadev->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(dmadev->base))
+		return PTR_ERR(dmadev->base);
+
+	dmadev->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(dmadev->clk)) {
+		dev_err(&pdev->dev, "Error: Missing controller clock\n");
+		return PTR_ERR(dmadev->clk);
+	}
+
+	dmadev->rst = devm_reset_control_get(&pdev->dev, NULL);
+	if (!IS_ERR(dmadev->rst)) {
+		reset_control_assert(dmadev->rst);
+		udelay(2);
+		reset_control_deassert(dmadev->rst);
+	}
+
+	dd = &dmadev->ddev;
+	dma_cap_set(DMA_SLAVE, dd->cap_mask);
+	dma_cap_set(DMA_PRIVATE, dd->cap_mask);
+	dma_cap_set(DMA_CYCLIC, dd->cap_mask);
+	dma_cap_set(DMA_MEMCPY, dd->cap_mask);
+	dd->device_alloc_chan_resources = stm32_mdma_alloc_chan_resources;
+	dd->device_free_chan_resources = stm32_mdma_free_chan_resources;
+	dd->device_tx_status = stm32_mdma_tx_status;
+	dd->device_issue_pending = stm32_mdma_issue_pending;
+	dd->device_prep_slave_sg = stm32_mdma_prep_slave_sg;
+	dd->device_prep_dma_cyclic = stm32_mdma_prep_dma_cyclic;
+	dd->device_prep_dma_memcpy = stm32_mdma_prep_dma_memcpy;
+	dd->device_config = stm32_mdma_slave_config;
+	dd->device_pause = stm32_mdma_pause;
+	dd->device_resume = stm32_mdma_resume;
+	dd->device_terminate_all = stm32_mdma_terminate_all;
+	dd->device_synchronize = stm32_mdma_synchronize;
+	dd->src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
+		BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
+		BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) |
+		BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
+	dd->dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
+		BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
+		BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) |
+		BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
+	dd->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV) |
+		BIT(DMA_MEM_TO_MEM);
+	dd->residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
+	dd->max_burst = STM32_MDMA_MAX_BURST;
+	dd->dev = &pdev->dev;
+	INIT_LIST_HEAD(&dd->channels);
+
+	for (i = 0; i < dmadev->nr_channels; i++) {
+		chan = &dmadev->chan[i];
+		chan->id = i;
+		chan->vchan.desc_free = stm32_mdma_desc_free;
+		vchan_init(&chan->vchan, dd);
+	}
+
+	dmadev->irq = platform_get_irq(pdev, 0);
+	if (dmadev->irq < 0) {
+		dev_err(&pdev->dev, "failed to get IRQ\n");
+		return dmadev->irq;
+	}
+
+	ret = devm_request_irq(&pdev->dev, dmadev->irq, stm32_mdma_irq_handler,
+			       0, dev_name(&pdev->dev), dmadev);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to request IRQ\n");
+		return ret;
+	}
+
+	ret = dma_async_device_register(dd);
+	if (ret)
+		return ret;
+
+	ret = of_dma_controller_register(of_node, stm32_mdma_of_xlate, dmadev);
+	if (ret < 0) {
+		dev_err(&pdev->dev,
+			"STM32 MDMA DMA OF registration failed %d\n", ret);
+		goto err_unregister;
+	}
+
+	platform_set_drvdata(pdev, dmadev);
+
+	dev_info(&pdev->dev, "STM32 MDMA driver registered\n");
+
+	return 0;
+
+err_unregister:
+	dma_async_device_unregister(dd);
+
+	return ret;
+}
+
+static struct platform_driver stm32_mdma_driver = {
+	.driver = {
+		.name = "stm32-mdma",
+		.of_match_table = stm32_mdma_of_match,
+	},
+};
+
+static int __init stm32_mdma_init(void)
+{
+	return platform_driver_probe(&stm32_mdma_driver, stm32_mdma_probe);
+}
+
+subsys_initcall(stm32_mdma_init);
-- 
1.9.1