dmaengine: Add STM32 DMA driver

This patch adds support for the STM32 DMA controller.

Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

3 files changed, 1154 insertions, 0 deletions

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index e6cd1a32025a..3a8ce67910c2 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -431,6 +431,18 @@ config STE_DMA40
 	help
 	  Support for ST-Ericsson DMA40 controller
 
+config STM32_DMA
+	bool "STMicroelectronics STM32 DMA support"
+	depends on ARCH_STM32
+	select DMA_ENGINE
+	select DMA_OF
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  Enable support for the on-chip DMA controller on STMicroelectronics
+	  STM32 MCUs.
+	  If you have a board based on such a MCU and wish to use DMA say Y or M
+	  here.
+
 config S3C24XX_DMAC
 	tristate "Samsung S3C24XX DMA support"
 	depends on ARCH_S3C24XX
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index ef9c099bd2b6..2dd0a067a0ca 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -56,6 +56,7 @@ obj-$(CONFIG_QCOM_BAM_DMA) += qcom_bam_dma.o
 obj-$(CONFIG_RENESAS_DMA) += sh/
 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_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-dma.c b/drivers/dma/stm32-dma.c
new file mode 100644
index 000000000000..12f3a3eddba9
--- /dev/null
+++ b/drivers/dma/stm32-dma.c
@@ -0,0 +1,1141 @@
+/*
+ * Driver for STM32 DMA controller
+ *
+ * Inspired by dma-jz4740.c and tegra20-apb-dma.c
+ *
+ * Copyright (C) M'boumba Cedric Madianga 2015
+ * Author: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
+ *
+ * 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/err.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/list.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_DMA_LISR			0x0000 /* DMA Low Int Status Reg */
+#define STM32_DMA_HISR			0x0004 /* DMA High Int Status Reg */
+#define STM32_DMA_LIFCR			0x0008 /* DMA Low Int Flag Clear Reg */
+#define STM32_DMA_HIFCR			0x000c /* DMA High Int Flag Clear Reg */
+#define STM32_DMA_TCI			BIT(5) /* Transfer Complete Interrupt */
+#define STM32_DMA_TEI			BIT(3) /* Transfer Error Interrupt */
+#define STM32_DMA_DMEI			BIT(2) /* Direct Mode Error Interrupt */
+#define STM32_DMA_FEI			BIT(0) /* FIFO Error Interrupt */
+
+/* DMA Stream x Configuration Register */
+#define STM32_DMA_SCR(x)		(0x0010 + 0x18 * (x)) /* x = 0..7 */
+#define STM32_DMA_SCR_REQ(n)		((n & 0x7) << 25)
+#define STM32_DMA_SCR_MBURST_MASK	GENMASK(24, 23)
+#define STM32_DMA_SCR_MBURST(n)	        ((n & 0x3) << 23)
+#define STM32_DMA_SCR_PBURST_MASK	GENMASK(22, 21)
+#define STM32_DMA_SCR_PBURST(n)	        ((n & 0x3) << 21)
+#define STM32_DMA_SCR_PL_MASK		GENMASK(17, 16)
+#define STM32_DMA_SCR_PL(n)		((n & 0x3) << 16)
+#define STM32_DMA_SCR_MSIZE_MASK	GENMASK(14, 13)
+#define STM32_DMA_SCR_MSIZE(n)		((n & 0x3) << 13)
+#define STM32_DMA_SCR_PSIZE_MASK	GENMASK(12, 11)
+#define STM32_DMA_SCR_PSIZE(n)		((n & 0x3) << 11)
+#define STM32_DMA_SCR_PSIZE_GET(n)	((n & STM32_DMA_SCR_PSIZE_MASK) >> 11)
+#define STM32_DMA_SCR_DIR_MASK		GENMASK(7, 6)
+#define STM32_DMA_SCR_DIR(n)		((n & 0x3) << 6)
+#define STM32_DMA_SCR_CT		BIT(19) /* Target in double buffer */
+#define STM32_DMA_SCR_DBM		BIT(18) /* Double Buffer Mode */
+#define STM32_DMA_SCR_PINCOS		BIT(15) /* Peripheral inc offset size */
+#define STM32_DMA_SCR_MINC		BIT(10) /* Memory increment mode */
+#define STM32_DMA_SCR_PINC		BIT(9) /* Peripheral increment mode */
+#define STM32_DMA_SCR_CIRC		BIT(8) /* Circular mode */
+#define STM32_DMA_SCR_PFCTRL		BIT(5) /* Peripheral Flow Controller */
+#define STM32_DMA_SCR_TCIE		BIT(4) /* Transfer Cplete Int Enable*/
+#define STM32_DMA_SCR_TEIE		BIT(2) /* Transfer Error Int Enable */
+#define STM32_DMA_SCR_DMEIE		BIT(1) /* Direct Mode Err Int Enable */
+#define STM32_DMA_SCR_EN		BIT(0) /* Stream Enable */
+#define STM32_DMA_SCR_CFG_MASK		(STM32_DMA_SCR_PINC \
+					| STM32_DMA_SCR_MINC \
+					| STM32_DMA_SCR_PINCOS \
+					| STM32_DMA_SCR_PL_MASK)
+#define STM32_DMA_SCR_IRQ_MASK		(STM32_DMA_SCR_TCIE \
+					| STM32_DMA_SCR_TEIE \
+					| STM32_DMA_SCR_DMEIE)
+
+/* DMA Stream x number of data register */
+#define STM32_DMA_SNDTR(x)		(0x0014 + 0x18 * (x))
+
+/* DMA stream peripheral address register */
+#define STM32_DMA_SPAR(x)		(0x0018 + 0x18 * (x))
+
+/* DMA stream x memory 0 address register */
+#define STM32_DMA_SM0AR(x)		(0x001c + 0x18 * (x))
+
+/* DMA stream x memory 1 address register */
+#define STM32_DMA_SM1AR(x)		(0x0020 + 0x18 * (x))
+
+/* DMA stream x FIFO control register */
+#define STM32_DMA_SFCR(x)		(0x0024 + 0x18 * (x))
+#define STM32_DMA_SFCR_FTH_MASK		GENMASK(1, 0)
+#define STM32_DMA_SFCR_FTH(n)		(n & STM32_DMA_SFCR_FTH_MASK)
+#define STM32_DMA_SFCR_FEIE		BIT(7) /* FIFO error interrupt enable */
+#define STM32_DMA_SFCR_DMDIS		BIT(2) /* Direct mode disable */
+#define STM32_DMA_SFCR_MASK		(STM32_DMA_SFCR_FEIE \
+					| STM32_DMA_SFCR_DMDIS)
+
+/* DMA direction */
+#define STM32_DMA_DEV_TO_MEM		0x00
+#define	STM32_DMA_MEM_TO_DEV		0x01
+#define	STM32_DMA_MEM_TO_MEM		0x02
+
+/* DMA priority level */
+#define STM32_DMA_PRIORITY_LOW		0x00
+#define STM32_DMA_PRIORITY_MEDIUM	0x01
+#define STM32_DMA_PRIORITY_HIGH		0x02
+#define STM32_DMA_PRIORITY_VERY_HIGH	0x03
+
+/* DMA FIFO threshold selection */
+#define STM32_DMA_FIFO_THRESHOLD_1QUARTERFULL		0x00
+#define STM32_DMA_FIFO_THRESHOLD_HALFFULL		0x01
+#define STM32_DMA_FIFO_THRESHOLD_3QUARTERSFULL		0x02
+#define STM32_DMA_FIFO_THRESHOLD_FULL			0x03
+
+#define STM32_DMA_MAX_DATA_ITEMS	0xffff
+#define STM32_DMA_MAX_CHANNELS		0x08
+#define STM32_DMA_MAX_REQUEST_ID	0x08
+#define STM32_DMA_MAX_DATA_PARAM	0x03
+
+enum stm32_dma_width {
+	STM32_DMA_BYTE,
+	STM32_DMA_HALF_WORD,
+	STM32_DMA_WORD,
+};
+
+enum stm32_dma_burst_size {
+	STM32_DMA_BURST_SINGLE,
+	STM32_DMA_BURST_INCR4,
+	STM32_DMA_BURST_INCR8,
+	STM32_DMA_BURST_INCR16,
+};
+
+struct stm32_dma_cfg {
+	u32 channel_id;
+	u32 request_line;
+	u32 stream_config;
+	u32 threshold;
+};
+
+struct stm32_dma_chan_reg {
+	u32 dma_lisr;
+	u32 dma_hisr;
+	u32 dma_lifcr;
+	u32 dma_hifcr;
+	u32 dma_scr;
+	u32 dma_sndtr;
+	u32 dma_spar;
+	u32 dma_sm0ar;
+	u32 dma_sm1ar;
+	u32 dma_sfcr;
+};
+
+struct stm32_dma_sg_req {
+	u32 len;
+	struct stm32_dma_chan_reg chan_reg;
+};
+
+struct stm32_dma_desc {
+	struct virt_dma_desc vdesc;
+	bool cyclic;
+	u32 num_sgs;
+	struct stm32_dma_sg_req sg_req[];
+};
+
+struct stm32_dma_chan {
+	struct virt_dma_chan vchan;
+	bool config_init;
+	bool busy;
+	u32 id;
+	u32 irq;
+	struct stm32_dma_desc *desc;
+	u32 next_sg;
+	struct dma_slave_config	dma_sconfig;
+	struct stm32_dma_chan_reg chan_reg;
+};
+
+struct stm32_dma_device {
+	struct dma_device ddev;
+	void __iomem *base;
+	struct clk *clk;
+	struct reset_control *rst;
+	bool mem2mem;
+	struct stm32_dma_chan chan[STM32_DMA_MAX_CHANNELS];
+};
+
+static struct stm32_dma_device *stm32_dma_get_dev(struct stm32_dma_chan *chan)
+{
+	return container_of(chan->vchan.chan.device, struct stm32_dma_device,
+			    ddev);
+}
+
+static struct stm32_dma_chan *to_stm32_dma_chan(struct dma_chan *c)
+{
+	return container_of(c, struct stm32_dma_chan, vchan.chan);
+}
+
+static struct stm32_dma_desc *to_stm32_dma_desc(struct virt_dma_desc *vdesc)
+{
+	return container_of(vdesc, struct stm32_dma_desc, vdesc);
+}
+
+static struct device *chan2dev(struct stm32_dma_chan *chan)
+{
+	return &chan->vchan.chan.dev->device;
+}
+
+static u32 stm32_dma_read(struct stm32_dma_device *dmadev, u32 reg)
+{
+	return readl_relaxed(dmadev->base + reg);
+}
+
+static void stm32_dma_write(struct stm32_dma_device *dmadev, u32 reg, u32 val)
+{
+	writel_relaxed(val, dmadev->base + reg);
+}
+
+static struct stm32_dma_desc *stm32_dma_alloc_desc(u32 num_sgs)
+{
+	return kzalloc(sizeof(struct stm32_dma_desc) +
+		       sizeof(struct stm32_dma_sg_req) * num_sgs, GFP_NOWAIT);
+}
+
+static int stm32_dma_get_width(struct stm32_dma_chan *chan,
+			       enum dma_slave_buswidth width)
+{
+	switch (width) {
+	case DMA_SLAVE_BUSWIDTH_1_BYTE:
+		return STM32_DMA_BYTE;
+	case DMA_SLAVE_BUSWIDTH_2_BYTES:
+		return STM32_DMA_HALF_WORD;
+	case DMA_SLAVE_BUSWIDTH_4_BYTES:
+		return STM32_DMA_WORD;
+	default:
+		dev_err(chan2dev(chan), "Dma bus width not supported\n");
+		return -EINVAL;
+	}
+}
+
+static int stm32_dma_get_burst(struct stm32_dma_chan *chan, u32 maxburst)
+{
+	switch (maxburst) {
+	case 0:
+	case 1:
+		return STM32_DMA_BURST_SINGLE;
+	case 4:
+		return STM32_DMA_BURST_INCR4;
+	case 8:
+		return STM32_DMA_BURST_INCR8;
+	case 16:
+		return STM32_DMA_BURST_INCR16;
+	default:
+		dev_err(chan2dev(chan), "Dma burst size not supported\n");
+		return -EINVAL;
+	}
+}
+
+static void stm32_dma_set_fifo_config(struct stm32_dma_chan *chan,
+				      u32 src_maxburst, u32 dst_maxburst)
+{
+	chan->chan_reg.dma_sfcr &= ~STM32_DMA_SFCR_MASK;
+	chan->chan_reg.dma_scr &= ~STM32_DMA_SCR_DMEIE;
+
+	if ((!src_maxburst) && (!dst_maxburst)) {
+		/* Using direct mode */
+		chan->chan_reg.dma_scr |= STM32_DMA_SCR_DMEIE;
+	} else {
+		/* Using FIFO mode */
+		chan->chan_reg.dma_sfcr |= STM32_DMA_SFCR_MASK;
+	}
+}
+
+static int stm32_dma_slave_config(struct dma_chan *c,
+				  struct dma_slave_config *config)
+{
+	struct stm32_dma_chan *chan = to_stm32_dma_chan(c);
+
+	memcpy(&chan->dma_sconfig, config, sizeof(*config));
+
+	chan->config_init = true;
+
+	return 0;
+}
+
+static u32 stm32_dma_irq_status(struct stm32_dma_chan *chan)
+{
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	u32 flags, dma_isr;
+
+	/*
+	 * Read "flags" from DMA_xISR register corresponding to the selected
+	 * DMA channel at the correct bit offset inside that register.
+	 *
+	 * If (ch % 4) is 2 or 3, left shift the mask by 16 bits.
+	 * If (ch % 4) is 1 or 3, additionally left shift the mask by 6 bits.
+	 */
+
+	if (chan->id & 4)
+		dma_isr = stm32_dma_read(dmadev, STM32_DMA_HISR);
+	else
+		dma_isr = stm32_dma_read(dmadev, STM32_DMA_LISR);
+
+	flags = dma_isr >> (((chan->id & 2) << 3) | ((chan->id & 1) * 6));
+
+	return flags;
+}
+
+static void stm32_dma_irq_clear(struct stm32_dma_chan *chan, u32 flags)
+{
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	u32 dma_ifcr;
+
+	/*
+	 * Write "flags" to the DMA_xIFCR register corresponding to the selected
+	 * DMA channel at the correct bit offset inside that register.
+	 *
+	 * If (ch % 4) is 2 or 3, left shift the mask by 16 bits.
+	 * If (ch % 4) is 1 or 3, additionally left shift the mask by 6 bits.
+	 */
+	dma_ifcr = flags << (((chan->id & 2) << 3) | ((chan->id & 1) * 6));
+
+	if (chan->id & 4)
+		stm32_dma_write(dmadev, STM32_DMA_HIFCR, dma_ifcr);
+	else
+		stm32_dma_write(dmadev, STM32_DMA_LIFCR, dma_ifcr);
+}
+
+static int stm32_dma_disable_chan(struct stm32_dma_chan *chan)
+{
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	unsigned long timeout = jiffies + msecs_to_jiffies(5000);
+	u32 dma_scr, id;
+
+	id = chan->id;
+	dma_scr = stm32_dma_read(dmadev, STM32_DMA_SCR(id));
+
+	if (dma_scr & STM32_DMA_SCR_EN) {
+		dma_scr &= ~STM32_DMA_SCR_EN;
+		stm32_dma_write(dmadev, STM32_DMA_SCR(id), dma_scr);
+
+		do {
+			dma_scr = stm32_dma_read(dmadev, STM32_DMA_SCR(id));
+			dma_scr &= STM32_DMA_SCR_EN;
+			if (!dma_scr)
+				break;
+
+			if (time_after_eq(jiffies, timeout)) {
+				dev_err(chan2dev(chan), "%s: timeout!\n",
+					__func__);
+				return -EBUSY;
+			}
+			cond_resched();
+		} while (1);
+	}
+
+	return 0;
+}
+
+static void stm32_dma_stop(struct stm32_dma_chan *chan)
+{
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	u32 dma_scr, dma_sfcr, status;
+	int ret;
+
+	/* Disable interrupts */
+	dma_scr = stm32_dma_read(dmadev, STM32_DMA_SCR(chan->id));
+	dma_scr &= ~STM32_DMA_SCR_IRQ_MASK;
+	stm32_dma_write(dmadev, STM32_DMA_SCR(chan->id), dma_scr);
+	dma_sfcr = stm32_dma_read(dmadev, STM32_DMA_SFCR(chan->id));
+	dma_sfcr &= ~STM32_DMA_SFCR_FEIE;
+	stm32_dma_write(dmadev, STM32_DMA_SFCR(chan->id), dma_sfcr);
+
+	/* Disable DMA */
+	ret = stm32_dma_disable_chan(chan);
+	if (ret < 0)
+		return;
+
+	/* Clear interrupt status if it is there */
+	status = stm32_dma_irq_status(chan);
+	if (status) {
+		dev_dbg(chan2dev(chan), "%s(): clearing interrupt: 0x%08x\n",
+			__func__, status);
+		stm32_dma_irq_clear(chan, status);
+	}
+
+	chan->busy = false;
+}
+
+static int stm32_dma_terminate_all(struct dma_chan *c)
+{
+	struct stm32_dma_chan *chan = to_stm32_dma_chan(c);
+	unsigned long flags;
+	LIST_HEAD(head);
+
+	spin_lock_irqsave(&chan->vchan.lock, flags);
+
+	if (chan->busy) {
+		stm32_dma_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_dma_dump_reg(struct stm32_dma_chan *chan)
+{
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	u32 scr = stm32_dma_read(dmadev, STM32_DMA_SCR(chan->id));
+	u32 ndtr = stm32_dma_read(dmadev, STM32_DMA_SNDTR(chan->id));
+	u32 spar = stm32_dma_read(dmadev, STM32_DMA_SPAR(chan->id));
+	u32 sm0ar = stm32_dma_read(dmadev, STM32_DMA_SM0AR(chan->id));
+	u32 sm1ar = stm32_dma_read(dmadev, STM32_DMA_SM1AR(chan->id));
+	u32 sfcr = stm32_dma_read(dmadev, STM32_DMA_SFCR(chan->id));
+
+	dev_dbg(chan2dev(chan), "SCR:   0x%08x\n", scr);
+	dev_dbg(chan2dev(chan), "NDTR:  0x%08x\n", ndtr);
+	dev_dbg(chan2dev(chan), "SPAR:  0x%08x\n", spar);
+	dev_dbg(chan2dev(chan), "SM0AR: 0x%08x\n", sm0ar);
+	dev_dbg(chan2dev(chan), "SM1AR: 0x%08x\n", sm1ar);
+	dev_dbg(chan2dev(chan), "SFCR:  0x%08x\n", sfcr);
+}
+
+static int stm32_dma_start_transfer(struct stm32_dma_chan *chan)
+{
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	struct virt_dma_desc *vdesc;
+	struct stm32_dma_sg_req *sg_req;
+	struct stm32_dma_chan_reg *reg;
+	u32 status;
+	int ret;
+
+	ret = stm32_dma_disable_chan(chan);
+	if (ret < 0)
+		return ret;
+
+	if (!chan->desc) {
+		vdesc = vchan_next_desc(&chan->vchan);
+		if (!vdesc)
+			return 0;
+
+		chan->desc = to_stm32_dma_desc(vdesc);
+		chan->next_sg = 0;
+	}
+
+	if (chan->next_sg == chan->desc->num_sgs)
+		chan->next_sg = 0;
+
+	sg_req = &chan->desc->sg_req[chan->next_sg];
+	reg = &sg_req->chan_reg;
+
+	stm32_dma_write(dmadev, STM32_DMA_SCR(chan->id), reg->dma_scr);
+	stm32_dma_write(dmadev, STM32_DMA_SPAR(chan->id), reg->dma_spar);
+	stm32_dma_write(dmadev, STM32_DMA_SM0AR(chan->id), reg->dma_sm0ar);
+	stm32_dma_write(dmadev, STM32_DMA_SFCR(chan->id), reg->dma_sfcr);
+	stm32_dma_write(dmadev, STM32_DMA_SM1AR(chan->id), reg->dma_sm1ar);
+	stm32_dma_write(dmadev, STM32_DMA_SNDTR(chan->id), reg->dma_sndtr);
+
+	chan->next_sg++;
+
+	/* Clear interrupt status if it is there */
+	status = stm32_dma_irq_status(chan);
+	if (status)
+		stm32_dma_irq_clear(chan, status);
+
+	stm32_dma_dump_reg(chan);
+
+	/* Start DMA */
+	reg->dma_scr |= STM32_DMA_SCR_EN;
+	stm32_dma_write(dmadev, STM32_DMA_SCR(chan->id), reg->dma_scr);
+
+	chan->busy = true;
+
+	return 0;
+}
+
+static void stm32_dma_configure_next_sg(struct stm32_dma_chan *chan)
+{
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	struct stm32_dma_sg_req *sg_req;
+	u32 dma_scr, dma_sm0ar, dma_sm1ar, id;
+
+	id = chan->id;
+	dma_scr = stm32_dma_read(dmadev, STM32_DMA_SCR(id));
+
+	if (dma_scr & STM32_DMA_SCR_DBM) {
+		if (chan->next_sg == chan->desc->num_sgs)
+			chan->next_sg = 0;
+
+		sg_req = &chan->desc->sg_req[chan->next_sg];
+
+		if (dma_scr & STM32_DMA_SCR_CT) {
+			dma_sm0ar = sg_req->chan_reg.dma_sm0ar;
+			stm32_dma_write(dmadev, STM32_DMA_SM0AR(id), dma_sm0ar);
+			dev_dbg(chan2dev(chan), "CT=1 <=> SM0AR: 0x%08x\n",
+				stm32_dma_read(dmadev, STM32_DMA_SM0AR(id)));
+		} else {
+			dma_sm1ar = sg_req->chan_reg.dma_sm1ar;
+			stm32_dma_write(dmadev, STM32_DMA_SM1AR(id), dma_sm1ar);
+			dev_dbg(chan2dev(chan), "CT=0 <=> SM1AR: 0x%08x\n",
+				stm32_dma_read(dmadev, STM32_DMA_SM1AR(id)));
+		}
+
+		chan->next_sg++;
+	}
+}
+
+static void stm32_dma_handle_chan_done(struct stm32_dma_chan *chan)
+{
+	if (chan->desc) {
+		if (chan->desc->cyclic) {
+			vchan_cyclic_callback(&chan->desc->vdesc);
+			stm32_dma_configure_next_sg(chan);
+		} else {
+			chan->busy = false;
+			if (chan->next_sg == chan->desc->num_sgs) {
+				list_del(&chan->desc->vdesc.node);
+				vchan_cookie_complete(&chan->desc->vdesc);
+				chan->desc = NULL;
+			}
+			stm32_dma_start_transfer(chan);
+		}
+	}
+}
+
+static irqreturn_t stm32_dma_chan_irq(int irq, void *devid)
+{
+	struct stm32_dma_chan *chan = devid;
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	u32 status, scr, sfcr;
+
+	spin_lock(&chan->vchan.lock);
+
+	status = stm32_dma_irq_status(chan);
+	scr = stm32_dma_read(dmadev, STM32_DMA_SCR(chan->id));
+	sfcr = stm32_dma_read(dmadev, STM32_DMA_SFCR(chan->id));
+
+	if ((status & STM32_DMA_TCI) && (scr & STM32_DMA_SCR_TCIE)) {
+		stm32_dma_irq_clear(chan, STM32_DMA_TCI);
+		stm32_dma_handle_chan_done(chan);
+
+	} else {
+		stm32_dma_irq_clear(chan, status);
+		dev_err(chan2dev(chan), "DMA error: status=0x%08x\n", status);
+	}
+
+	spin_unlock(&chan->vchan.lock);
+
+	return IRQ_HANDLED;
+}
+
+static void stm32_dma_issue_pending(struct dma_chan *c)
+{
+	struct stm32_dma_chan *chan = to_stm32_dma_chan(c);
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&chan->vchan.lock, flags);
+	if (!chan->busy) {
+		if (vchan_issue_pending(&chan->vchan) && !chan->desc) {
+			ret = stm32_dma_start_transfer(chan);
+			if ((chan->desc->cyclic) && (!ret))
+				stm32_dma_configure_next_sg(chan);
+		}
+	}
+	spin_unlock_irqrestore(&chan->vchan.lock, flags);
+}
+
+static int stm32_dma_set_xfer_param(struct stm32_dma_chan *chan,
+				    enum dma_transfer_direction direction,
+				    enum dma_slave_buswidth *buswidth)
+{
+	enum dma_slave_buswidth src_addr_width, dst_addr_width;
+	int src_bus_width, dst_bus_width;
+	int src_burst_size, dst_burst_size;
+	u32 src_maxburst, dst_maxburst;
+	dma_addr_t src_addr, dst_addr;
+	u32 dma_scr = 0;
+
+	src_addr_width = chan->dma_sconfig.src_addr_width;
+	dst_addr_width = chan->dma_sconfig.dst_addr_width;
+	src_maxburst = chan->dma_sconfig.src_maxburst;
+	dst_maxburst = chan->dma_sconfig.dst_maxburst;
+	src_addr = chan->dma_sconfig.src_addr;
+	dst_addr = chan->dma_sconfig.dst_addr;
+
+	switch (direction) {
+	case DMA_MEM_TO_DEV:
+		dst_bus_width = stm32_dma_get_width(chan, dst_addr_width);
+		if (dst_bus_width < 0)
+			return dst_bus_width;
+
+		dst_burst_size = stm32_dma_get_burst(chan, dst_maxburst);
+		if (dst_burst_size < 0)
+			return dst_burst_size;
+
+		if (!src_addr_width)
+			src_addr_width = dst_addr_width;
+
+		src_bus_width = stm32_dma_get_width(chan, src_addr_width);
+		if (src_bus_width < 0)
+			return src_bus_width;
+
+		src_burst_size = stm32_dma_get_burst(chan, src_maxburst);
+		if (src_burst_size < 0)
+			return src_burst_size;
+
+		dma_scr = STM32_DMA_SCR_DIR(STM32_DMA_MEM_TO_DEV) |
+			STM32_DMA_SCR_PSIZE(dst_bus_width) |
+			STM32_DMA_SCR_MSIZE(src_bus_width) |
+			STM32_DMA_SCR_PBURST(dst_burst_size) |
+			STM32_DMA_SCR_MBURST(src_burst_size);
+
+		chan->chan_reg.dma_spar = chan->dma_sconfig.dst_addr;
+		*buswidth = dst_addr_width;
+		break;
+
+	case DMA_DEV_TO_MEM:
+		src_bus_width = stm32_dma_get_width(chan, src_addr_width);
+		if (src_bus_width < 0)
+			return src_bus_width;
+
+		src_burst_size = stm32_dma_get_burst(chan, src_maxburst);
+		if (src_burst_size < 0)
+			return src_burst_size;
+
+		if (!dst_addr_width)
+			dst_addr_width = src_addr_width;
+
+		dst_bus_width = stm32_dma_get_width(chan, dst_addr_width);
+		if (dst_bus_width < 0)
+			return dst_bus_width;
+
+		dst_burst_size = stm32_dma_get_burst(chan, dst_maxburst);
+		if (dst_burst_size < 0)
+			return dst_burst_size;
+
+		dma_scr = STM32_DMA_SCR_DIR(STM32_DMA_DEV_TO_MEM) |
+			STM32_DMA_SCR_PSIZE(src_bus_width) |
+			STM32_DMA_SCR_MSIZE(dst_bus_width) |
+			STM32_DMA_SCR_PBURST(src_burst_size) |
+			STM32_DMA_SCR_MBURST(dst_burst_size);
+
+		chan->chan_reg.dma_spar = chan->dma_sconfig.src_addr;
+		*buswidth = chan->dma_sconfig.src_addr_width;
+		break;
+
+	default:
+		dev_err(chan2dev(chan), "Dma direction is not supported\n");
+		return -EINVAL;
+	}
+
+	stm32_dma_set_fifo_config(chan, src_maxburst, dst_maxburst);
+
+	chan->chan_reg.dma_scr &= ~(STM32_DMA_SCR_DIR_MASK |
+			STM32_DMA_SCR_PSIZE_MASK | STM32_DMA_SCR_MSIZE_MASK |
+			STM32_DMA_SCR_PBURST_MASK | STM32_DMA_SCR_MBURST_MASK);
+	chan->chan_reg.dma_scr |= dma_scr;
+
+	return 0;
+}
+
+static void stm32_dma_clear_reg(struct stm32_dma_chan_reg *regs)
+{
+	memset(regs, 0, sizeof(struct stm32_dma_chan_reg));
+}
+
+static struct dma_async_tx_descriptor *stm32_dma_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_dma_chan *chan = to_stm32_dma_chan(c);
+	struct stm32_dma_desc *desc;
+	struct scatterlist *sg;
+	enum dma_slave_buswidth buswidth;
+	u32 nb_data_items;
+	int i, ret;
+
+	if (!chan->config_init) {
+		dev_err(chan2dev(chan), "dma channel is not configured\n");
+		return NULL;
+	}
+
+	if (sg_len < 1) {
+		dev_err(chan2dev(chan), "Invalid segment length %d\n", sg_len);
+		return NULL;
+	}
+
+	desc = stm32_dma_alloc_desc(sg_len);
+	if (!desc)
+		return NULL;
+
+	ret = stm32_dma_set_xfer_param(chan, direction, &buswidth);
+	if (ret < 0)
+		goto err;
+
+	/* Set peripheral flow controller */
+	if (chan->dma_sconfig.device_fc)
+		chan->chan_reg.dma_scr |= STM32_DMA_SCR_PFCTRL;
+	else
+		chan->chan_reg.dma_scr &= ~STM32_DMA_SCR_PFCTRL;
+
+	for_each_sg(sgl, sg, sg_len, i) {
+		desc->sg_req[i].len = sg_dma_len(sg);
+
+		nb_data_items = desc->sg_req[i].len / buswidth;
+		if (nb_data_items > STM32_DMA_MAX_DATA_ITEMS) {
+			dev_err(chan2dev(chan), "nb items not supported\n");
+			goto err;
+		}
+
+		stm32_dma_clear_reg(&desc->sg_req[i].chan_reg);
+		desc->sg_req[i].chan_reg.dma_scr = chan->chan_reg.dma_scr;
+		desc->sg_req[i].chan_reg.dma_sfcr = chan->chan_reg.dma_sfcr;
+		desc->sg_req[i].chan_reg.dma_spar = chan->chan_reg.dma_spar;
+		desc->sg_req[i].chan_reg.dma_sm0ar = sg_dma_address(sg);
+		desc->sg_req[i].chan_reg.dma_sm1ar = sg_dma_address(sg);
+		desc->sg_req[i].chan_reg.dma_sndtr = nb_data_items;
+	}
+
+	desc->num_sgs = sg_len;
+	desc->cyclic = false;
+
+	return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
+
+err:
+	kfree(desc);
+	return NULL;
+}
+
+static struct dma_async_tx_descriptor *stm32_dma_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_dma_chan *chan = to_stm32_dma_chan(c);
+	struct stm32_dma_desc *desc;
+	enum dma_slave_buswidth buswidth;
+	u32 num_periods, nb_data_items;
+	int i, ret;
+
+	if (!buf_len || !period_len) {
+		dev_err(chan2dev(chan), "Invalid buffer/period len\n");
+		return NULL;
+	}
+
+	if (!chan->config_init) {
+		dev_err(chan2dev(chan), "dma channel is not configured\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;
+	}
+
+	ret = stm32_dma_set_xfer_param(chan, direction, &buswidth);
+	if (ret < 0)
+		return NULL;
+
+	nb_data_items = period_len / buswidth;
+	if (nb_data_items > STM32_DMA_MAX_DATA_ITEMS) {
+		dev_err(chan2dev(chan), "number of items not supported\n");
+		return NULL;
+	}
+
+	/*  Enable Circular mode or double buffer mode */
+	if (buf_len == period_len)
+		chan->chan_reg.dma_scr |= STM32_DMA_SCR_CIRC;
+	else
+		chan->chan_reg.dma_scr |= STM32_DMA_SCR_DBM;
+
+	/* Clear periph ctrl if client set it */
+	chan->chan_reg.dma_scr &= ~STM32_DMA_SCR_PFCTRL;
+
+	num_periods = buf_len / period_len;
+
+	desc = stm32_dma_alloc_desc(num_periods);
+	if (!desc)
+		return NULL;
+
+	for (i = 0; i < num_periods; i++) {
+		desc->sg_req[i].len = period_len;
+
+		stm32_dma_clear_reg(&desc->sg_req[i].chan_reg);
+		desc->sg_req[i].chan_reg.dma_scr = chan->chan_reg.dma_scr;
+		desc->sg_req[i].chan_reg.dma_sfcr = chan->chan_reg.dma_sfcr;
+		desc->sg_req[i].chan_reg.dma_spar = chan->chan_reg.dma_spar;
+		desc->sg_req[i].chan_reg.dma_sm0ar = buf_addr;
+		desc->sg_req[i].chan_reg.dma_sm1ar = buf_addr;
+		desc->sg_req[i].chan_reg.dma_sndtr = nb_data_items;
+		buf_addr += period_len;
+	}
+
+	desc->num_sgs = num_periods;
+	desc->cyclic = true;
+
+	return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
+}
+
+static struct dma_async_tx_descriptor *stm32_dma_prep_dma_memcpy(
+	struct dma_chan *c, dma_addr_t dest,
+	dma_addr_t src, size_t len, unsigned long flags)
+{
+	struct stm32_dma_chan *chan = to_stm32_dma_chan(c);
+	u32 num_sgs;
+	struct stm32_dma_desc *desc;
+	size_t xfer_count, offset;
+	int i;
+
+	num_sgs = DIV_ROUND_UP(len, STM32_DMA_MAX_DATA_ITEMS);
+	desc = stm32_dma_alloc_desc(num_sgs);
+	if (!desc)
+		return NULL;
+
+	for (offset = 0, i = 0; offset < len; offset += xfer_count, i++) {
+		xfer_count = min_t(size_t, len - offset,
+				   STM32_DMA_MAX_DATA_ITEMS);
+
+		desc->sg_req[i].len = xfer_count;
+
+		stm32_dma_clear_reg(&desc->sg_req[i].chan_reg);
+		desc->sg_req[i].chan_reg.dma_scr =
+			STM32_DMA_SCR_DIR(STM32_DMA_MEM_TO_MEM) |
+			STM32_DMA_SCR_MINC |
+			STM32_DMA_SCR_PINC |
+			STM32_DMA_SCR_TCIE |
+			STM32_DMA_SCR_TEIE;
+		desc->sg_req[i].chan_reg.dma_sfcr = STM32_DMA_SFCR_DMDIS |
+			STM32_DMA_SFCR_FTH(STM32_DMA_FIFO_THRESHOLD_FULL) |
+			STM32_DMA_SFCR_FEIE;
+		desc->sg_req[i].chan_reg.dma_spar = src + offset;
+		desc->sg_req[i].chan_reg.dma_sm0ar = dest + offset;
+		desc->sg_req[i].chan_reg.dma_sndtr = xfer_count;
+	}
+
+	desc->num_sgs = num_sgs;
+	desc->cyclic = false;
+
+	return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
+}
+
+static size_t stm32_dma_desc_residue(struct stm32_dma_chan *chan,
+				     struct stm32_dma_desc *desc,
+				     u32 next_sg)
+{
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	u32 dma_scr, width, residue, count;
+	int i;
+
+	residue = 0;
+
+	for (i = next_sg; i < desc->num_sgs; i++)
+		residue += desc->sg_req[i].len;
+
+	if (next_sg != 0) {
+		dma_scr = stm32_dma_read(dmadev, STM32_DMA_SCR(chan->id));
+		width = STM32_DMA_SCR_PSIZE_GET(dma_scr);
+		count = stm32_dma_read(dmadev, STM32_DMA_SNDTR(chan->id));
+
+		residue += count << width;
+	}
+
+	return residue;
+}
+
+static enum dma_status stm32_dma_tx_status(struct dma_chan *c,
+					   dma_cookie_t cookie,
+					   struct dma_tx_state *state)
+{
+	struct stm32_dma_chan *chan = to_stm32_dma_chan(c);
+	struct virt_dma_desc *vdesc;
+	enum dma_status status;
+	unsigned long flags;
+	u32 residue;
+
+	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 (cookie == chan->desc->vdesc.tx.cookie) {
+		residue = stm32_dma_desc_residue(chan, chan->desc,
+						 chan->next_sg);
+	} else if (vdesc) {
+		residue = stm32_dma_desc_residue(chan,
+						 to_stm32_dma_desc(vdesc), 0);
+	} else {
+		residue = 0;
+	}
+
+	dma_set_residue(state, residue);
+
+	spin_unlock_irqrestore(&chan->vchan.lock, flags);
+
+	return status;
+}
+
+static int stm32_dma_alloc_chan_resources(struct dma_chan *c)
+{
+	struct stm32_dma_chan *chan = to_stm32_dma_chan(c);
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	int ret;
+
+	chan->config_init = false;
+	ret = clk_prepare_enable(dmadev->clk);
+	if (ret < 0) {
+		dev_err(chan2dev(chan), "clk_prepare_enable failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = stm32_dma_disable_chan(chan);
+	if (ret < 0)
+		clk_disable_unprepare(dmadev->clk);
+
+	return ret;
+}
+
+static void stm32_dma_free_chan_resources(struct dma_chan *c)
+{
+	struct stm32_dma_chan *chan = to_stm32_dma_chan(c);
+	struct stm32_dma_device *dmadev = stm32_dma_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_dma_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));
+}
+
+static void stm32_dma_desc_free(struct virt_dma_desc *vdesc)
+{
+	kfree(container_of(vdesc, struct stm32_dma_desc, vdesc));
+}
+
+void stm32_dma_set_config(struct stm32_dma_chan *chan,
+			  struct stm32_dma_cfg *cfg)
+{
+	stm32_dma_clear_reg(&chan->chan_reg);
+
+	chan->chan_reg.dma_scr = cfg->stream_config & STM32_DMA_SCR_CFG_MASK;
+	chan->chan_reg.dma_scr |= STM32_DMA_SCR_REQ(cfg->request_line);
+
+	/* Enable Interrupts  */
+	chan->chan_reg.dma_scr |= STM32_DMA_SCR_TEIE | STM32_DMA_SCR_TCIE;
+
+	chan->chan_reg.dma_sfcr = cfg->threshold & STM32_DMA_SFCR_FTH_MASK;
+}
+
+static struct dma_chan *stm32_dma_of_xlate(struct of_phandle_args *dma_spec,
+					   struct of_dma *ofdma)
+{
+	struct stm32_dma_device *dmadev = ofdma->of_dma_data;
+	struct stm32_dma_cfg cfg;
+	struct stm32_dma_chan *chan;
+	struct dma_chan *c;
+
+	if (dma_spec->args_count < 3)
+		return NULL;
+
+	cfg.channel_id = dma_spec->args[0];
+	cfg.request_line = dma_spec->args[1];
+	cfg.stream_config = dma_spec->args[2];
+	cfg.threshold = 0;
+
+	if ((cfg.channel_id >= STM32_DMA_MAX_CHANNELS) || (cfg.request_line >=
+				STM32_DMA_MAX_REQUEST_ID))
+		return NULL;
+
+	if (dma_spec->args_count > 3)
+		cfg.threshold = dma_spec->args[3];
+
+	chan = &dmadev->chan[cfg.channel_id];
+
+	c = dma_get_slave_channel(&chan->vchan.chan);
+	if (c)
+		stm32_dma_set_config(chan, &cfg);
+
+	return c;
+}
+
+static const struct of_device_id stm32_dma_of_match[] = {
+	{ .compatible = "st,stm32-dma", },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, stm32_dma_of_match);
+
+static int stm32_dma_probe(struct platform_device *pdev)
+{
+	struct stm32_dma_chan *chan;
+	struct stm32_dma_device *dmadev;
+	struct dma_device *dd;
+	const struct of_device_id *match;
+	struct resource *res;
+	int i, ret;
+
+	match = of_match_device(stm32_dma_of_match, &pdev->dev);
+	if (!match) {
+		dev_err(&pdev->dev, "Error: No device match found\n");
+		return -ENODEV;
+	}
+
+	dmadev = devm_kzalloc(&pdev->dev, sizeof(*dmadev), GFP_KERNEL);
+	if (!dmadev)
+		return -ENOMEM;
+
+	dd = &dmadev->ddev;
+
+	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->mem2mem = of_property_read_bool(pdev->dev.of_node,
+						"st,mem2mem");
+
+	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);
+	}
+
+	dma_cap_set(DMA_SLAVE, dd->cap_mask);
+	dma_cap_set(DMA_PRIVATE, dd->cap_mask);
+	dma_cap_set(DMA_CYCLIC, dd->cap_mask);
+	dd->device_alloc_chan_resources = stm32_dma_alloc_chan_resources;
+	dd->device_free_chan_resources = stm32_dma_free_chan_resources;
+	dd->device_tx_status = stm32_dma_tx_status;
+	dd->device_issue_pending = stm32_dma_issue_pending;
+	dd->device_prep_slave_sg = stm32_dma_prep_slave_sg;
+	dd->device_prep_dma_cyclic = stm32_dma_prep_dma_cyclic;
+	dd->device_config = stm32_dma_slave_config;
+	dd->device_terminate_all = stm32_dma_terminate_all;
+	dd->src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
+		BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
+		BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
+	dd->dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
+		BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
+		BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
+	dd->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
+	dd->residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
+	dd->dev = &pdev->dev;
+	INIT_LIST_HEAD(&dd->channels);
+
+	if (dmadev->mem2mem) {
+		dma_cap_set(DMA_MEMCPY, dd->cap_mask);
+		dd->device_prep_dma_memcpy = stm32_dma_prep_dma_memcpy;
+		dd->directions |= BIT(DMA_MEM_TO_MEM);
+	}
+
+	for (i = 0; i < STM32_DMA_MAX_CHANNELS; i++) {
+		chan = &dmadev->chan[i];
+		chan->id = i;
+		chan->vchan.desc_free = stm32_dma_desc_free;
+		vchan_init(&chan->vchan, dd);
+	}
+
+	ret = dma_async_device_register(dd);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < STM32_DMA_MAX_CHANNELS; i++) {
+		chan = &dmadev->chan[i];
+		res = platform_get_resource(pdev, IORESOURCE_IRQ, i);
+		if (!res) {
+			ret = -EINVAL;
+			dev_err(&pdev->dev, "No irq resource for chan %d\n", i);
+			goto err_unregister;
+		}
+		chan->irq = res->start;
+		ret = devm_request_irq(&pdev->dev, chan->irq,
+				       stm32_dma_chan_irq, 0,
+				       dev_name(chan2dev(chan)), chan);
+		if (ret) {
+			dev_err(&pdev->dev,
+				"request_irq failed with err %d channel %d\n",
+				ret, i);
+			goto err_unregister;
+		}
+	}
+
+	ret = of_dma_controller_register(pdev->dev.of_node,
+					 stm32_dma_of_xlate, dmadev);
+	if (ret < 0) {
+		dev_err(&pdev->dev,
+			"STM32 DMA DMA OF registration failed %d\n", ret);
+		goto err_unregister;
+	}
+
+	platform_set_drvdata(pdev, dmadev);
+
+	dev_info(&pdev->dev, "STM32 DMA driver registered\n");
+
+	return 0;
+
+err_unregister:
+	dma_async_device_unregister(dd);
+
+	return ret;
+}
+
+static struct platform_driver stm32_dma_driver = {
+	.driver = {
+		.name = "stm32-dma",
+		.of_match_table = stm32_dma_of_match,
+	},
+};
+
+static int __init stm32_dma_init(void)
+{
+	return platform_driver_probe(&stm32_dma_driver, stm32_dma_probe);
+}
+subsys_initcall(stm32_dma_init);