[PATCH 2/2] spi: add driver for STM32 SPI controller

[Amelie Delaunay]

The STM32 Serial Peripheral Interface (SPI) can be used to communicate
with external devices while using the specific synchronous protocol. It
supports a half-duplex, full-duplex and simplex synchronous, serial
communication with external devices with 4-bit to 16/32-bit per word. It
has two 8x/16x 8-bit embedded Rx and TxFIFOs with DMA capability. It can
operate in master or slave mode.

Signed-off-by: Amelie Delaunay <amelie.delaunay@xxxxxx>
---
 drivers/spi/Kconfig     |   10 +
 drivers/spi/Makefile    |    1 +
 drivers/spi/spi-stm32.c | 1266 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 1277 insertions(+)
 create mode 100644 drivers/spi/spi-stm32.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index fd1b4fd..9b31351 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -627,6 +627,16 @@ config SPI_SIRF
 	help
 	  SPI driver for CSR SiRFprimaII SoCs
 
+config SPI_STM32
+	tristate "STMicroelectronics STM32 SPI controller"
+	depends on ARCH_STM32 || COMPILE_TEST
+	help
+	  SPI driver for STMicroelectonics STM32 SoCs.
+
+	  STM32 SPI controller supports DMA and PIO modes. When DMA
+	  is not available, the driver automatically falls back to
+	  PIO mode.
+
 config SPI_ST_SSC4
 	tristate "STMicroelectronics SPI SSC-based driver"
 	depends on ARCH_STI || COMPILE_TEST
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 31dccfb..a3ae2b7 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -90,6 +90,7 @@ obj-$(CONFIG_SPI_SH_HSPI)		+= spi-sh-hspi.o
 obj-$(CONFIG_SPI_SH_MSIOF)		+= spi-sh-msiof.o
 obj-$(CONFIG_SPI_SH_SCI)		+= spi-sh-sci.o
 obj-$(CONFIG_SPI_SIRF)		+= spi-sirf.o
+obj-$(CONFIG_SPI_STM32) 		+= spi-stm32.o
 obj-$(CONFIG_SPI_ST_SSC4)		+= spi-st-ssc4.o
 obj-$(CONFIG_SPI_SUN4I)			+= spi-sun4i.o
 obj-$(CONFIG_SPI_SUN6I)			+= spi-sun6i.o
diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
new file mode 100644
index 0000000..0553f61
--- /dev/null
+++ b/drivers/spi/spi-stm32.c
@@ -0,0 +1,1266 @@
+/*
+ * STMicroelectronics STM32 SPI Controller driver (master mode only)
+ *
+ * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
+ * Author(s): Amelie Delaunay <amelie.delaunay@xxxxxx> for STMicroelectronics.
+ *
+ * License terms: GPL V2.0.
+ *
+ * spi_stm32 driver is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * spi_stm32 driver 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
+ * spi_stm32 driver. If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <linux/debugfs.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/dmaengine.h>
+#include <linux/gpio.h>
+#include <linux/interrupt.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/reset.h>
+#include <linux/spi/spi.h>
+
+#define DRIVER_NAME "spi_stm32"
+
+/* STM32 SPI registers */
+#define STM32_SPI_CR1		0x00
+#define STM32_SPI_CR2		0x04
+#define STM32_SPI_CFG1		0x08
+#define STM32_SPI_CFG2		0x0C
+#define STM32_SPI_IER		0x10
+#define STM32_SPI_SR		0x14
+#define STM32_SPI_IFCR		0x18
+#define STM32_SPI_TXDR		0x20
+#define STM32_SPI_RXDR		0x30
+#define STM32_SPI_I2SCFGR	0x50
+
+/* STM32_SPI_CR1 bit fields */
+#define SPI_CR1_SPE		BIT(0)
+#define SPI_CR1_MASRX		BIT(8)
+#define SPI_CR1_CSTART		BIT(9)
+#define SPI_CR1_CSUSP		BIT(10)
+#define SPI_CR1_HDDIR		BIT(11)
+#define SPI_CR1_SSI		BIT(12)
+
+/* STM32_SPI_CR2 bit fields */
+#define SPI_CR2_TSIZE_SHIFT	0
+#define SPI_CR2_TSIZE		GENMASK(15, 0)
+
+/* STM32_SPI_CFG1 bit fields */
+#define SPI_CFG1_DSIZE_SHIFT	0
+#define SPI_CFG1_DSIZE		GENMASK(4, 0)
+#define SPI_CFG1_FTHLV_SHIFT	5
+#define SPI_CFG1_FTHLV		GENMASK(8, 5)
+#define SPI_CFG1_RXDMAEN	BIT(14)
+#define SPI_CFG1_TXDMAEN	BIT(15)
+#define SPI_CFG1_MBR_SHIFT	28
+#define SPI_CFG1_MBR		GENMASK(30, 28)
+#define SPI_CFG1_MBR_MIN	0
+#define SPI_CFG1_MBR_MAX	(GENMASK(30, 28) >> 28)
+
+/* STM32_SPI_CFG2 bit fields */
+#define SPI_CFG2_MIDI_SHIFT	4
+#define SPI_CFG2_MIDI		GENMASK(7, 4)
+#define SPI_CFG2_COMM_SHIFT	17
+#define SPI_CFG2_COMM		GENMASK(18, 17)
+#define SPI_CFG2_SP_SHIFT	19
+#define SPI_CFG2_SP		GENMASK(21, 19)
+#define SPI_CFG2_MASTER		BIT(22)
+#define SPI_CFG2_LSBFRST	BIT(23)
+#define SPI_CFG2_CPHA		BIT(24)
+#define SPI_CFG2_CPOL		BIT(25)
+#define SPI_CFG2_SSM		BIT(26)
+#define SPI_CFG2_AFCNTR		BIT(31)
+
+/* STM32_SPI_IER bit fields */
+#define SPI_IER_RXPIE		BIT(0)
+#define SPI_IER_TXPIE		BIT(1)
+#define SPI_IER_DXPIE		BIT(2)
+#define SPI_IER_EOTIE		BIT(3)
+#define SPI_IER_TXTFIE		BIT(4)
+#define SPI_IER_OVRIE		BIT(6)
+#define SPI_IER_MODFIE		BIT(9)
+#define SPI_IER_ALL		GENMASK(10, 0)
+
+/* STM32_SPI_SR bit fields */
+#define SPI_SR_RXP		BIT(0)
+#define SPI_SR_TXP		BIT(1)
+#define SPI_SR_EOT		BIT(3)
+#define SPI_SR_OVR		BIT(6)
+#define SPI_SR_MODF		BIT(9)
+#define SPI_SR_SUSP		BIT(11)
+#define SPI_SR_RXPLVL_SHIFT	13
+#define SPI_SR_RXPLVL		GENMASK(14, 13)
+#define SPI_SR_RXWNE		BIT(15)
+
+/* STM32_SPI_IFCR bit fields */
+#define SPI_IFCR_ALL		GENMASK(11, 3)
+
+/* STM32_SPI_I2SCFGR bit fields */
+#define SPI_I2SCFGR_I2SMOD	BIT(0)
+
+/* SPI Master Baud Rate min/max divisor */
+#define SPI_MBR_DIV_MIN		(2 << SPI_CFG1_MBR_MIN)
+#define SPI_MBR_DIV_MAX		(2 << SPI_CFG1_MBR_MAX)
+
+/* SPI Communication mode */
+#define SPI_FULL_DUPLEX		0
+#define SPI_SIMPLEX_TX		1
+#define SPI_SIMPLEX_RX		2
+#define SPI_HALF_DUPLEX		3
+
+#define SPI_1HZ_NS		1000000000
+
+/**
+ * struct stm32_spi - private data of the SPI controller
+ * @dev: driver model representation of the controller
+ * @master: controller master interface
+ * @base: virtual memory area
+ * @clk: hw kernel clock feeding the SPI clock generator
+ * @clk_rate: rate of the hw kernel clock feeding the SPI clock generator
+ * @rst: SPI controller reset line
+ * @lock: prevent I/O concurrent access
+ * @irq: SPI controller interrupt line
+ * @fifo_size: size of the embedded fifo in bytes
+ * @cur_midi: master inter-data idleness in ns
+ * @cur_speed: speed configured in Hz
+ * @cur_bpw: number of bits in a single SPI data frame
+ * @cur_fthlv: fifo threshold level (data frames in a single data packet)
+ * @cur_comm: SPI communication mode
+ * @cur_xferlen: current transfer length in bytes
+ * @cur_usedma: boolean to know if dma is used in current transfer
+ * @tx_buf: data to be written, or NULL
+ * @rx_buf: data to be read, or NULL
+ * @tx_len: number of data to be written in bytes
+ * @rx_len: number of data to be read in bytes
+ * @dma_tx: dma channel for TX transfer
+ * @dma_rx: dma channel for RX transfer
+ * @phys_addr: SPI registers physical base address
+ */
+struct stm32_spi {
+	struct device *dev;
+	struct spi_master *master;
+	void __iomem *base;
+	struct clk *clk;
+	u32 clk_rate;
+	struct reset_control *rst;
+	spinlock_t lock; /* prevent I/O concurrent access */
+	int irq;
+	unsigned int fifo_size;
+
+	unsigned int cur_midi;
+	unsigned int cur_speed;
+	unsigned int cur_bpw;
+	unsigned int cur_fthlv;
+	unsigned int cur_comm;
+	unsigned int cur_xferlen;
+	bool cur_usedma;
+
+	const void *tx_buf;
+	void *rx_buf;
+	int tx_len;
+	int rx_len;
+	struct dma_chan *dma_tx;
+	struct dma_chan *dma_rx;
+	dma_addr_t phys_addr;
+};
+
+static inline void stm32_spi_set_bits(struct stm32_spi *spi,
+				      u32 offset, u32 bits)
+{
+	writel_relaxed(readl_relaxed(spi->base + offset) | bits,
+		       spi->base + offset);
+}
+
+static inline void stm32_spi_clr_bits(struct stm32_spi *spi,
+				      u32 offset, u32 bits)
+{
+	writel_relaxed(readl_relaxed(spi->base + offset) & ~bits,
+		       spi->base + offset);
+}
+
+/**
+ * stm32_spi_get_fifo_size - Return fifo size
+ * @spi: pointer to the spi controller data structure
+ */
+static int stm32_spi_get_fifo_size(struct stm32_spi *spi)
+{
+	unsigned long flags;
+	u32 count = 0;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	stm32_spi_set_bits(spi, STM32_SPI_CR1, SPI_CR1_SPE);
+
+	while (readl_relaxed(spi->base + STM32_SPI_SR) & SPI_SR_TXP)
+		writeb_relaxed(++count, spi->base + STM32_SPI_TXDR);
+
+	stm32_spi_clr_bits(spi, STM32_SPI_CR1, SPI_CR1_SPE);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	dev_dbg(spi->dev, "%d x 8-bit fifo size\n", count);
+
+	return count;
+}
+
+/**
+ * stm32_spi_get_bpw_mask - Return bits per word mask
+ * @spi: pointer to the spi controller data structure
+ */
+static int stm32_spi_get_bpw_mask(struct stm32_spi *spi)
+{
+	unsigned long flags;
+	u32 cfg1, max_bpw;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	/*
+	 * The most significant bit at DSIZE bit field is reserved when the
+	 * maximum data size of periperal instances is limited to 16-bit
+	 */
+	stm32_spi_set_bits(spi, STM32_SPI_CFG1, SPI_CFG1_DSIZE);
+
+	cfg1 = readl_relaxed(spi->base + STM32_SPI_CFG1);
+	max_bpw = (cfg1 & SPI_CFG1_DSIZE) >> SPI_CFG1_DSIZE_SHIFT;
+	max_bpw += 1;
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	dev_dbg(spi->dev, "%d-bit maximum data frame\n", max_bpw);
+
+	return SPI_BPW_RANGE_MASK(4, max_bpw);
+}
+
+/**
+ * stm32_spi_prepare_mbr - Determine SPI_CFG1.MBR value
+ * @spi: pointer to the spi controller data structure
+ * @speed_hz: requested speed
+ *
+ * Return SPI_CFG1.MBR value in case of success or -EINVAL
+ */
+static int stm32_spi_prepare_mbr(struct stm32_spi *spi, u32 speed_hz)
+{
+	u32 div, mbrdiv;
+
+	div = DIV_ROUND_UP(spi->clk_rate, speed_hz);
+
+	/*
+	 * SPI framework set xfer->speed_hz to master->max_speed_hz if
+	 * xfer->speed_hz is greater than master->max_speed_hz, and it returns
+	 * an error when xfer->speed_hz is lower than master->min_speed_hz, so
+	 * no need to check it there.
+	 * However, we need to ensure the following calculations.
+	 */
+	if ((div < SPI_MBR_DIV_MIN) &&
+	    (div > SPI_MBR_DIV_MAX))
+		return -EINVAL;
+
+	/* Determine the first power of 2 greater than or equal to div */
+	mbrdiv = (div & (div - 1)) ? fls(div) : fls(div) - 1;
+
+	spi->cur_speed = spi->clk_rate / (1 << mbrdiv);
+
+	return mbrdiv - 1;
+}
+
+/**
+ * stm32_spi_prepare_fthlv - Determine FIFO threshold level
+ * @spi: pointer to the spi controller data structure
+ */
+static u32 stm32_spi_prepare_fthlv(struct stm32_spi *spi)
+{
+	u32 fthlv, half_fifo;
+
+	/* data packet should not exceed 1/2 of fifo space */
+	half_fifo = (spi->fifo_size / 2);
+
+	fthlv = (spi->cur_bpw <= 8) ? half_fifo :
+		(spi->cur_bpw <= 16) ? (half_fifo / 2) :
+		(half_fifo / 4);
+
+	/* align packet size with data registers access */
+	if (spi->cur_bpw > 8)
+		fthlv -= (fthlv % 2); /* multiple of 2 */
+	else
+		fthlv -= (fthlv % 4); /* multiple of 4 */
+
+	return fthlv;
+}
+
+/**
+ * stm32_spi_write_txfifo - Write bytes in Transmit Data Register
+ * @spi: pointer to the spi controller data structure
+ *
+ * Read from tx_buf depends on remaining bytes to avoid to read beyond
+ * tx_buf end.
+ */
+static void stm32_spi_write_txfifo(struct stm32_spi *spi)
+{
+	while ((spi->tx_len > 0) &&
+	       (readl_relaxed(spi->base + STM32_SPI_SR) & SPI_SR_TXP)) {
+		u32 offs = spi->cur_xferlen - spi->tx_len;
+
+		if (spi->tx_len >= sizeof(u32)) {
+			const u32 *tx_buf32 = (const u32 *)(spi->tx_buf + offs);
+
+			writel_relaxed(*tx_buf32, spi->base + STM32_SPI_TXDR);
+			spi->tx_len -= sizeof(u32);
+		} else if (spi->tx_len >= sizeof(u16)) {
+			const u16 *tx_buf16 = (const u16 *)(spi->tx_buf + offs);
+
+			writew_relaxed(*tx_buf16, spi->base + STM32_SPI_TXDR);
+			spi->tx_len -= sizeof(u16);
+		} else {
+			const u8 *tx_buf8 = (const u8 *)(spi->tx_buf + offs);
+
+			writeb_relaxed(*tx_buf8, spi->base + STM32_SPI_TXDR);
+			spi->tx_len -= sizeof(u8);
+		}
+	}
+
+	dev_dbg(spi->dev, "%s: %d bytes left\n", __func__, spi->tx_len);
+}
+
+/**
+ * stm32_spi_read_rxfifo - Read bytes in Receive Data Register
+ * @spi: pointer to the spi controller data structure
+ *
+ * Write in rx_buf depends on remaining bytes to avoid to write beyond
+ * rx_buf end.
+ */
+static void stm32_spi_read_rxfifo(struct stm32_spi *spi, bool flush)
+{
+	u32 sr = readl_relaxed(spi->base + STM32_SPI_SR);
+	u32 rxplvl = (sr & SPI_SR_RXPLVL) >> SPI_SR_RXPLVL_SHIFT;
+
+	while ((spi->rx_len > 0) &&
+	       ((sr & SPI_SR_RXP) ||
+		(flush && ((sr & SPI_SR_RXWNE) || (rxplvl > 0))))) {
+		u32 offs = spi->cur_xferlen - spi->rx_len;
+
+		if ((spi->rx_len >= sizeof(u32)) ||
+		    (flush && (sr & SPI_SR_RXWNE))) {
+			u32 *rx_buf32 = (u32 *)(spi->rx_buf + offs);
+
+			*rx_buf32 = readl_relaxed(spi->base + STM32_SPI_RXDR);
+			spi->rx_len -= sizeof(u32);
+		} else if ((spi->rx_len >= sizeof(u16)) ||
+			   (flush && (rxplvl >= 2 || spi->cur_bpw > 8))) {
+			u16 *rx_buf16 = (u16 *)(spi->rx_buf + offs);
+
+			*rx_buf16 = readw_relaxed(spi->base + STM32_SPI_RXDR);
+			spi->rx_len -= sizeof(u16);
+		} else {
+			u8 *rx_buf8 = (u8 *)(spi->rx_buf + offs);
+
+			*rx_buf8 = readb_relaxed(spi->base + STM32_SPI_RXDR);
+			spi->rx_len -= sizeof(u8);
+		}
+
+		sr = readl_relaxed(spi->base + STM32_SPI_SR);
+		rxplvl = (sr & SPI_SR_RXPLVL) >> SPI_SR_RXPLVL_SHIFT;
+	}
+
+	dev_dbg(spi->dev, "%s%s: %d bytes left\n", __func__,
+		flush ? "(flush)" : "", spi->rx_len);
+}
+
+/**
+ * stm32_spi_enable - Enable SPI controller
+ * @spi: pointer to the spi controller data structure
+ *
+ * SPI data transfer is enabled but spi_ker_ck is idle.
+ * SPI_CFG1 and SPI_CFG2 are now write protected.
+ */
+static void stm32_spi_enable(struct stm32_spi *spi)
+{
+	dev_dbg(spi->dev, "enable controller\n");
+
+	stm32_spi_set_bits(spi, STM32_SPI_CR1, SPI_CR1_SPE);
+}
+
+/**
+ * stm32_spi_disable - Disable SPI controller
+ * @spi: pointer to the spi controller data structure
+ *
+ * RX-Fifo is flushed when SPI controller is disabled. To prevent any data
+ * loss, use stm32_spi_read_rxfifo(flush) to read the remaining bytes in
+ * RX-Fifo.
+ */
+static void stm32_spi_disable(struct stm32_spi *spi)
+{
+	unsigned long flags;
+	u32 cr1, sr;
+
+	dev_dbg(spi->dev, "disable controller\n");
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	cr1 = readl_relaxed(spi->base + STM32_SPI_CR1);
+
+	if (!(cr1 & SPI_CR1_SPE)) {
+		spin_unlock_irqrestore(&spi->lock, flags);
+		return;
+	}
+
+	/* Wait on EOT or suspend the flow */
+	if (readl_relaxed_poll_timeout_atomic(spi->base + STM32_SPI_SR,
+					      sr, !(sr & SPI_SR_EOT),
+					      10, 100000) < 0) {
+		if (cr1 & SPI_CR1_CSTART) {
+			writel_relaxed(cr1 | SPI_CR1_CSUSP,
+				       spi->base + STM32_SPI_CR1);
+			if (readl_relaxed_poll_timeout_atomic(
+						spi->base + STM32_SPI_SR,
+						sr, !(sr & SPI_SR_SUSP),
+						10, 100000) < 0)
+				dev_warn(spi->dev,
+					 "Suspend request timeout\n");
+		}
+	}
+
+	if (!spi->cur_usedma && spi->rx_buf && (spi->rx_len > 0))
+		stm32_spi_read_rxfifo(spi, true);
+
+	if (spi->cur_usedma && spi->tx_buf)
+		dmaengine_terminate_all(spi->dma_tx);
+	if (spi->cur_usedma && spi->rx_buf)
+		dmaengine_terminate_all(spi->dma_rx);
+
+	stm32_spi_clr_bits(spi, STM32_SPI_CR1, SPI_CR1_SPE);
+
+	stm32_spi_clr_bits(spi, STM32_SPI_CFG1, SPI_CFG1_TXDMAEN |
+						SPI_CFG1_RXDMAEN);
+
+	/* Disable interrupts and clear status flags */
+	writel_relaxed(0, spi->base + STM32_SPI_IER);
+	writel_relaxed(SPI_IFCR_ALL, spi->base + STM32_SPI_IFCR);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+}
+
+/**
+ * stm32_spi_can_dma - Determine if the transfer is eligible for DMA use
+ *
+ * If the current transfer size is greater than fifo size, use DMA.
+ */
+static bool stm32_spi_can_dma(struct spi_master *master,
+			      struct spi_device *spi_dev,
+			      struct spi_transfer *transfer)
+{
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+
+	dev_dbg(spi->dev, "%s: %s\n", __func__,
+		(!!(transfer->len > spi->fifo_size)) ? "true" : "false");
+
+	return !!(transfer->len > spi->fifo_size);
+}
+
+/**
+ * stm32_spi_irq - Interrupt handler for SPI controller events
+ * @irq: interrupt line
+ * @dev_id: SPI controller master interface
+ */
+static irqreturn_t stm32_spi_irq(int irq, void *dev_id)
+{
+	struct spi_master *master = dev_id;
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+	u32 sr, ier, mask;
+	unsigned long flags;
+	bool end = false;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	sr = readl_relaxed(spi->base + STM32_SPI_SR);
+	ier = readl_relaxed(spi->base + STM32_SPI_IER);
+
+	mask = ier;
+	/* EOTIE is triggered on EOT, SUSP and TXC events. */
+	mask |= SPI_SR_SUSP;
+	/*
+	 * When TXTF is set, DXPIE and TXPIE are cleared. So in case of
+	 * Full-Duplex, need to poll RXP event to know if there are remaining
+	 * data, before disabling SPI.
+	 */
+	mask |= ((spi->rx_buf && !spi->cur_usedma) ? SPI_SR_RXP : 0);
+
+	if (!(sr & mask)) {
+		dev_dbg(spi->dev, "spurious IT (sr=0x%08x, ier=0x%08x)\n",
+			sr, ier);
+		spin_unlock_irqrestore(&spi->lock, flags);
+		return IRQ_NONE;
+	}
+
+	if (sr & SPI_SR_SUSP) {
+		dev_warn(spi->dev, "Communication suspended\n");
+		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
+			stm32_spi_read_rxfifo(spi, false);
+	}
+
+	if (sr & SPI_SR_MODF) {
+		dev_warn(spi->dev, "Mode fault: transfer aborted\n");
+		end = true;
+	}
+
+	if (sr & SPI_SR_OVR) {
+		dev_warn(spi->dev, "Overrun: received value discarded\n");
+		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
+			stm32_spi_read_rxfifo(spi, false);
+	}
+
+	if (sr & SPI_SR_EOT) {
+		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
+			stm32_spi_read_rxfifo(spi, true);
+		end = true;
+	}
+
+	if (sr & SPI_SR_TXP)
+		if (!spi->cur_usedma && (spi->tx_buf && (spi->tx_len > 0)))
+			stm32_spi_write_txfifo(spi);
+
+	if (sr & SPI_SR_RXP)
+		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
+			stm32_spi_read_rxfifo(spi, false);
+
+	writel_relaxed(mask, spi->base + STM32_SPI_IFCR);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	if (end) {
+		spi_finalize_current_transfer(master);
+		stm32_spi_disable(spi);
+	}
+
+	return IRQ_HANDLED;
+}
+
+/**
+ * stm32_spi_setup - setup device chip select
+ */
+static int stm32_spi_setup(struct spi_device *spi_dev)
+{
+	int ret = 0;
+
+	if (!gpio_is_valid(spi_dev->cs_gpio)) {
+		dev_err(&spi_dev->dev, "%d is not a valid gpio\n",
+			spi_dev->cs_gpio);
+		return -EINVAL;
+	}
+
+	dev_dbg(&spi_dev->dev, "%s: set gpio%d output %s\n", __func__,
+		spi_dev->cs_gpio,
+		(spi_dev->mode & SPI_CS_HIGH) ? "low" : "high");
+
+	ret = gpio_direction_output(spi_dev->cs_gpio,
+				    !(spi_dev->mode & SPI_CS_HIGH));
+
+	return ret;
+}
+
+/**
+ * stm32_spi_prepare_msg - set up the controller to transfer a single message
+ */
+static int stm32_spi_prepare_msg(struct spi_master *master,
+				 struct spi_message *msg)
+{
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+	struct spi_device *spi_dev = msg->spi;
+	struct device_node *np = spi_dev->dev.of_node;
+	unsigned long flags;
+	u32 cfg2_clrb = 0, cfg2_setb = 0;
+
+	/* SPI slave device may need time between data frames */
+	spi->cur_midi = 0;
+	if (np && !of_property_read_u32(np, "st,spi-midi", &spi->cur_midi))
+		dev_dbg(spi->dev, "%dns inter-data idleness\n", spi->cur_midi);
+
+	if (spi_dev->mode & SPI_CPOL)
+		cfg2_setb |= SPI_CFG2_CPOL;
+	else
+		cfg2_clrb |= SPI_CFG2_CPOL;
+
+	if (spi_dev->mode & SPI_CPHA)
+		cfg2_setb |= SPI_CFG2_CPHA;
+	else
+		cfg2_clrb |= SPI_CFG2_CPHA;
+
+	if (spi_dev->mode & SPI_LSB_FIRST)
+		cfg2_setb |= SPI_CFG2_LSBFRST;
+	else
+		cfg2_clrb |= SPI_CFG2_LSBFRST;
+
+	dev_dbg(spi->dev, "cpol=%d cpha=%d lsb_first=%d cs_high=%d\n",
+		spi_dev->mode & SPI_CPOL,
+		spi_dev->mode & SPI_CPHA,
+		spi_dev->mode & SPI_LSB_FIRST,
+		spi_dev->mode & SPI_CS_HIGH);
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	if (cfg2_clrb || cfg2_setb)
+		writel_relaxed(
+			(readl_relaxed(spi->base + STM32_SPI_CFG2) &
+				~cfg2_clrb) | cfg2_setb,
+			       spi->base + STM32_SPI_CFG2);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	return 0;
+}
+
+/**
+ * stm32_spi_dma_cb - dma callback
+ *
+ * DMA callback is called when the transfer is complete or when an error
+ * occurs. If the transfer is complete, EOT flag is raised.
+ */
+static void stm32_spi_dma_cb(void *data)
+{
+	struct stm32_spi *spi = data;
+	unsigned long flags;
+	u32 sr;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	sr = readl_relaxed(spi->base + STM32_SPI_SR);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	if (!(sr & SPI_SR_EOT)) {
+		dev_warn(spi->dev, "DMA callback (sr=0x%08x)\n", sr);
+
+		spi_finalize_current_transfer(spi->master);
+		stm32_spi_disable(spi);
+	}
+}
+
+/**
+ * stm32_spi_dma_config - configure dma slave channel depending on current
+ *			  transfer bits_per_word.
+ */
+static void stm32_spi_dma_config(struct stm32_spi *spi,
+				 struct dma_slave_config *dma_conf,
+				 enum dma_transfer_direction dir)
+{
+	enum dma_slave_buswidth buswidth;
+	u32 maxburst;
+
+	buswidth = (spi->cur_bpw <= 8) ? DMA_SLAVE_BUSWIDTH_1_BYTE :
+		   (spi->cur_bpw <= 16) ? DMA_SLAVE_BUSWIDTH_2_BYTES :
+		   DMA_SLAVE_BUSWIDTH_4_BYTES;
+
+	/* Valid for DMA Half or Full Fifo threshold */
+	maxburst = (spi->cur_fthlv == 2) ? 1 : spi->cur_fthlv;
+
+	memset(dma_conf, 0, sizeof(struct dma_slave_config));
+	dma_conf->direction = dir;
+	if (dma_conf->direction == DMA_DEV_TO_MEM) { /* RX */
+		dma_conf->src_addr = spi->phys_addr + STM32_SPI_RXDR;
+		dma_conf->src_addr_width = buswidth;
+		dma_conf->src_maxburst = maxburst;
+
+		dev_dbg(spi->dev, "Rx DMA config buswidth=%d, maxburst=%d\n",
+			buswidth, maxburst);
+	} else if (dma_conf->direction == DMA_MEM_TO_DEV) { /* TX */
+		dma_conf->dst_addr = spi->phys_addr + STM32_SPI_TXDR;
+		dma_conf->dst_addr_width = buswidth;
+		dma_conf->dst_maxburst = maxburst;
+
+		dev_dbg(spi->dev, "Tx DMA config buswidth=%d, maxburst=%d\n",
+			buswidth, maxburst);
+	}
+}
+
+/**
+ * stm32_spi_transfer_one_irq - transfer a single spi_transfer using
+ *				interrupts
+ *
+ * It must returns 0 if the transfer is finished or 1 if the transfer is still
+ * in progress.
+ */
+static int stm32_spi_transfer_one_irq(struct stm32_spi *spi)
+{
+	unsigned long flags;
+	u32 ier = 0;
+
+	/* Enable the interrupts relative to the current communication mode */
+	if (spi->tx_buf && spi->rx_buf)	/* Full Duplex */
+		ier |= SPI_IER_DXPIE;
+	else if (spi->tx_buf)		/* Half-Duplex TX dir or Simplex TX */
+		ier |= SPI_IER_TXPIE;
+	else if (spi->rx_buf)		/* Half-Duplex RX dir or Simplex RX */
+		ier |= SPI_IER_RXPIE;
+
+	/* Enable the interrupts relative to the end of transfer */
+	ier |= SPI_IER_EOTIE | SPI_IER_TXTFIE |	SPI_IER_OVRIE |	SPI_IER_MODFIE;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	stm32_spi_enable(spi);
+
+	/* Be sure to have data in fifo before starting data transfer */
+	if (spi->tx_buf)
+		stm32_spi_write_txfifo(spi);
+
+	stm32_spi_set_bits(spi, STM32_SPI_CR1, SPI_CR1_CSTART);
+
+	writel_relaxed(ier, spi->base + STM32_SPI_IER);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	return 1;
+}
+
+/**
+ * stm32_spi_transfer_one_dma - transfer a single spi_transfer using DMA
+ *
+ * It must returns 0 if the transfer is finished or 1 if the transfer is still
+ * in progress.
+ */
+static int stm32_spi_transfer_one_dma(struct stm32_spi *spi,
+				      struct spi_transfer *xfer)
+{
+	struct dma_slave_config tx_dma_conf, rx_dma_conf;
+	struct dma_async_tx_descriptor *tx_dma_desc, *rx_dma_desc;
+	unsigned long flags;
+	u32 ier = 0;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	rx_dma_desc = NULL;
+	if (spi->rx_buf) {
+		stm32_spi_dma_config(spi, &rx_dma_conf, DMA_DEV_TO_MEM);
+		dmaengine_slave_config(spi->dma_rx, &rx_dma_conf);
+
+		/* Enable Rx DMA request */
+		stm32_spi_set_bits(spi, STM32_SPI_CFG1, SPI_CFG1_RXDMAEN);
+
+		rx_dma_desc = dmaengine_prep_slave_sg(
+					spi->dma_rx, xfer->rx_sg.sgl,
+					xfer->rx_sg.nents,
+					rx_dma_conf.direction,
+					DMA_PREP_INTERRUPT);
+
+		rx_dma_desc->callback = stm32_spi_dma_cb;
+		rx_dma_desc->callback_param = spi;
+	}
+
+	tx_dma_desc = NULL;
+	if (spi->tx_buf) {
+		stm32_spi_dma_config(spi, &tx_dma_conf, DMA_MEM_TO_DEV);
+		dmaengine_slave_config(spi->dma_tx, &tx_dma_conf);
+
+		tx_dma_desc = dmaengine_prep_slave_sg(
+					spi->dma_tx, xfer->tx_sg.sgl,
+					xfer->tx_sg.nents,
+					tx_dma_conf.direction,
+					DMA_PREP_INTERRUPT);
+
+		if (spi->cur_comm == SPI_SIMPLEX_TX) {
+			tx_dma_desc->callback = stm32_spi_dma_cb;
+			tx_dma_desc->callback_param = spi;
+		}
+	}
+
+	if ((spi->tx_buf && !tx_dma_desc) ||
+	    (spi->rx_buf && !rx_dma_desc))
+		goto dma_desc_error;
+
+	if (rx_dma_desc) {
+		if (dma_submit_error(dmaengine_submit(rx_dma_desc))) {
+			dev_err(spi->dev, "Rx DMA submit failed\n");
+			goto dma_desc_error;
+		}
+		/* Enable Rx DMA channel */
+		dma_async_issue_pending(spi->dma_rx);
+	}
+
+	if (tx_dma_desc) {
+		if (dma_submit_error(dmaengine_submit(tx_dma_desc))) {
+			dev_err(spi->dev, "Tx DMA submit failed\n");
+			goto dma_submit_error;
+		}
+		/* Enable Tx DMA channel */
+		dma_async_issue_pending(spi->dma_tx);
+
+		/* Enable Tx DMA request */
+		stm32_spi_set_bits(spi, STM32_SPI_CFG1, SPI_CFG1_TXDMAEN);
+	}
+
+	/* Enable the interrupts relative to the end of transfer */
+	ier |= SPI_IER_EOTIE | SPI_IER_TXTFIE |	SPI_IER_OVRIE |	SPI_IER_MODFIE;
+	writel_relaxed(ier, spi->base + STM32_SPI_IER);
+
+	stm32_spi_enable(spi);
+
+	stm32_spi_set_bits(spi, STM32_SPI_CR1, SPI_CR1_CSTART);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	return 1;
+
+dma_submit_error:
+	if (spi->rx_buf)
+		dmaengine_terminate_all(spi->dma_rx);
+
+dma_desc_error:
+	stm32_spi_clr_bits(spi, STM32_SPI_CFG1, SPI_CFG1_RXDMAEN);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	dev_info(spi->dev, "DMA issue: fall back to irq transfer\n");
+
+	return stm32_spi_transfer_one_irq(spi);
+}
+
+/**
+ * stm32_spi_transfer_one_setup - common setup to transfer a single
+ *				  spi_transfer either using DMA or
+ *				  interrupts.
+ */
+static int stm32_spi_transfer_one_setup(struct stm32_spi *spi,
+					struct spi_device *spi_dev,
+					struct spi_transfer *transfer)
+{
+	unsigned long flags;
+	u32 cfg1_clrb = 0, cfg1_setb = 0, cfg2_clrb = 0, cfg2_setb = 0;
+	u32 mode, nb_words;
+	int ret = 0;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	if (spi->cur_bpw != transfer->bits_per_word) {
+		u32 bpw, fthlv;
+
+		spi->cur_bpw = transfer->bits_per_word;
+		bpw = spi->cur_bpw - 1;
+
+		cfg1_clrb |= SPI_CFG1_DSIZE;
+		cfg1_setb |= (bpw << SPI_CFG1_DSIZE_SHIFT) & SPI_CFG1_DSIZE;
+
+		spi->cur_fthlv = stm32_spi_prepare_fthlv(spi);
+		fthlv = spi->cur_fthlv - 1;
+
+		cfg1_clrb |= SPI_CFG1_FTHLV;
+		cfg1_setb |= (fthlv << SPI_CFG1_FTHLV_SHIFT) & SPI_CFG1_FTHLV;
+	}
+
+	if (spi->cur_speed != transfer->speed_hz) {
+		u32 mbr;
+
+		/* Update spi->cur_speed with real clock speed */
+		mbr = stm32_spi_prepare_mbr(spi, transfer->speed_hz);
+		if (mbr < 0) {
+			ret = mbr;
+			goto out;
+		}
+
+		transfer->speed_hz = spi->cur_speed;
+
+		cfg1_clrb |= SPI_CFG1_MBR;
+		cfg1_setb |= (mbr << SPI_CFG1_MBR_SHIFT) & SPI_CFG1_MBR;
+	}
+
+	if (cfg1_clrb || cfg1_setb)
+		writel_relaxed((readl_relaxed(spi->base + STM32_SPI_CFG1) &
+				~cfg1_clrb) | cfg1_setb,
+			       spi->base + STM32_SPI_CFG1);
+
+	mode = SPI_FULL_DUPLEX;
+	if (spi_dev->mode & SPI_3WIRE) { /* MISO/MOSI signals shared */
+		/*
+		 * SPI_3WIRE and xfer->tx_buf != NULL and xfer->rx_buf != NULL
+		 * is forbidden und unvalidated by SPI subsystem so depending
+		 * on the valid buffer, we can determine the direction of the
+		 * transfer.
+		 */
+		mode = SPI_HALF_DUPLEX;
+		if (!transfer->tx_buf)
+			stm32_spi_clr_bits(spi, STM32_SPI_CR1, SPI_CR1_HDDIR);
+		else if (!transfer->rx_buf)
+			stm32_spi_set_bits(spi, STM32_SPI_CR1, SPI_CR1_HDDIR);
+	} else {
+		if (!transfer->tx_buf)
+			mode = SPI_SIMPLEX_RX;
+		else if (!transfer->rx_buf)
+			mode = SPI_SIMPLEX_TX;
+	}
+	if (spi->cur_comm != mode) {
+		spi->cur_comm = mode;
+
+		cfg2_clrb |= SPI_CFG2_COMM;
+		cfg2_setb |= (mode << SPI_CFG2_COMM_SHIFT) & SPI_CFG2_COMM;
+	}
+
+	cfg2_clrb |= SPI_CFG2_MIDI;
+	if ((transfer->len > 1) && (spi->cur_midi > 0)) {
+		u32 sck_period_ns = DIV_ROUND_UP(SPI_1HZ_NS, spi->cur_speed);
+		u32 midi = min((u32)DIV_ROUND_UP(spi->cur_midi, sck_period_ns),
+			       (u32)SPI_CFG2_MIDI >> SPI_CFG2_MIDI_SHIFT);
+
+		dev_dbg(spi->dev, "period=%dns, midi=%d(=%dns)\n",
+			sck_period_ns, midi, midi * sck_period_ns);
+
+		cfg2_setb |= (midi << SPI_CFG2_MIDI_SHIFT) & SPI_CFG2_MIDI;
+	}
+
+	if (cfg2_clrb || cfg2_setb)
+		writel_relaxed((readl_relaxed(spi->base + STM32_SPI_CFG2) &
+				~cfg2_clrb) | cfg2_setb,
+			       spi->base + STM32_SPI_CFG2);
+
+	nb_words = DIV_ROUND_UP(transfer->len * 8,
+				(spi->cur_bpw <= 8) ? 8 :
+				(spi->cur_bpw <= 16) ? 16 : 32);
+	nb_words <<= SPI_CR2_TSIZE_SHIFT;
+
+	if (nb_words <= SPI_CR2_TSIZE) {
+		writel_relaxed(nb_words, spi->base + STM32_SPI_CR2);
+	} else {
+		ret = -EMSGSIZE;
+		goto out;
+	}
+
+	spi->cur_xferlen = transfer->len;
+
+	dev_dbg(spi->dev, "transfer communication mode set to %d\n",
+		spi->cur_comm);
+	dev_dbg(spi->dev,
+		"data frame of %d-bit, data packet of %d data frames\n",
+		spi->cur_bpw, spi->cur_fthlv);
+	dev_dbg(spi->dev, "speed set to %dHz\n", spi->cur_speed);
+	dev_dbg(spi->dev, "transfer of %d bytes (%d data frames)\n",
+		spi->cur_xferlen, nb_words);
+	dev_dbg(spi->dev, "dma %s\n",
+		(spi->cur_usedma) ? "enabled" : "disabled");
+
+out:
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	return ret;
+}
+
+/**
+ * stm32_spi_transfer_one - transfer a single spi_transfer
+ *
+ * It must return 0 if the transfer is finished or 1 if the transfer is still
+ * in progress.
+ */
+static int stm32_spi_transfer_one(struct spi_master *master,
+				  struct spi_device *spi_dev,
+				  struct spi_transfer *transfer)
+{
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+	int ret;
+
+	spi->tx_buf = transfer->tx_buf;
+	spi->rx_buf = transfer->rx_buf;
+	spi->tx_len = spi->tx_buf ? transfer->len : 0;
+	spi->rx_len = spi->rx_buf ? transfer->len : 0;
+
+	spi->cur_usedma = stm32_spi_can_dma(master, spi_dev, transfer);
+
+	ret = stm32_spi_transfer_one_setup(spi, spi_dev, transfer);
+	if (ret) {
+		dev_err(spi->dev, "SPI transfer setup failed\n");
+		return ret;
+	}
+
+	if (spi->cur_usedma)
+		return stm32_spi_transfer_one_dma(spi, transfer);
+	else
+		return stm32_spi_transfer_one_irq(spi);
+}
+
+/**
+ * stm32_spi_unprepare_msg - relax the hardware
+ *
+ * Normally, if TSIZE has been configured, we should relax the hardware at the
+ * reception of the EOT interrupt. But in case of error, EOT will not be
+ * raised. So the subsystem unprepare_message call allows us to properly
+ * complete the transfer from an hardware point of view.
+ */
+static int stm32_spi_unprepare_msg(struct spi_master *master,
+				   struct spi_message *msg)
+{
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+
+	stm32_spi_disable(spi);
+
+	return 0;
+}
+
+/**
+ * stm32_spi_config - Configure SPI controller as SPI master
+ */
+static int stm32_spi_config(struct stm32_spi *spi)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	/* Ensure I2SMOD bit is kept cleared */
+	stm32_spi_clr_bits(spi, STM32_SPI_I2SCFGR, SPI_I2SCFGR_I2SMOD);
+
+	/*
+	 * - SS input value high
+	 * - transmitter half duplex direction
+	 * - automatic communication suspend when RX-Fifo is full
+	 */
+	stm32_spi_set_bits(spi, STM32_SPI_CR1, SPI_CR1_SSI |
+					       SPI_CR1_HDDIR |
+					       SPI_CR1_MASRX);
+
+	/*
+	 * - Set the master mode (default Motorola mode)
+	 * - Consider 1 master/n slaves configuration and
+	 *   SS input value is determined by the SSI bit
+	 * - keep control of all associated GPIOs
+	 */
+	stm32_spi_set_bits(spi, STM32_SPI_CFG2, SPI_CFG2_MASTER |
+						SPI_CFG2_SSM |
+						SPI_CFG2_AFCNTR);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	return 0;
+}
+
+static const struct of_device_id stm32_spi_of_match[] = {
+	{ .compatible = "st,stm32-spi", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, stm32_spi_of_match);
+
+static int stm32_spi_probe(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct stm32_spi *spi;
+	struct resource *res;
+	int i, ret;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(struct stm32_spi));
+	if (!master) {
+		dev_err(&pdev->dev, "spi master allocation failed\n");
+		return -ENOMEM;
+	}
+	platform_set_drvdata(pdev, master);
+
+	spi = spi_master_get_devdata(master);
+	spi->dev = &pdev->dev;
+	spi->master = master;
+	spin_lock_init(&spi->lock);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	spi->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(spi->base)) {
+		ret = PTR_ERR(spi->base);
+		goto err_master_put;
+	}
+	spi->phys_addr = (dma_addr_t)res->start;
+
+	spi->irq = platform_get_irq(pdev, 0);
+	if (spi->irq <= 0) {
+		dev_err(&pdev->dev, "no irq: %d\n", spi->irq);
+		ret = -ENOENT;
+		goto err_master_put;
+	}
+	ret = devm_request_threaded_irq(&pdev->dev, spi->irq, NULL,
+					stm32_spi_irq, IRQF_ONESHOT,
+					pdev->name, master);
+	if (ret) {
+		dev_err(&pdev->dev, "irq%d request failed: %d\n", spi->irq,
+			ret);
+		goto err_master_put;
+	}
+
+	spi->clk = devm_clk_get(&pdev->dev, 0);
+	if (IS_ERR(spi->clk)) {
+		ret = PTR_ERR(spi->clk);
+		dev_err(&pdev->dev, "clk get failed: %d\n", ret);
+		goto err_master_put;
+	}
+
+	ret = clk_prepare_enable(spi->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "clk enable failed: %d\n", ret);
+		goto err_master_put;
+	}
+	spi->clk_rate = clk_get_rate(spi->clk);
+	if (!spi->clk_rate) {
+		dev_err(&pdev->dev, "clk rate = 0\n");
+		ret = -EINVAL;
+		goto err_master_put;
+	}
+
+	spi->rst = devm_reset_control_get(&pdev->dev, NULL);
+	if (!IS_ERR(spi->rst)) {
+		reset_control_assert(spi->rst);
+		udelay(2);
+		reset_control_deassert(spi->rst);
+	}
+
+	spi->fifo_size = stm32_spi_get_fifo_size(spi);
+
+	ret = stm32_spi_config(spi);
+	if (ret) {
+		dev_err(&pdev->dev, "controller configuration failed: %d\n",
+			ret);
+		goto err_clk_disable;
+	}
+
+	master->dev.of_node = pdev->dev.of_node;
+	master->auto_runtime_pm = true;
+	master->bus_num = pdev->id;
+	master->mode_bits = SPI_MODE_3 | SPI_CS_HIGH | SPI_LSB_FIRST |
+			    SPI_3WIRE | SPI_LOOP;
+	master->bits_per_word_mask = stm32_spi_get_bpw_mask(spi);
+	master->max_speed_hz = spi->clk_rate / SPI_MBR_DIV_MIN;
+	master->min_speed_hz = spi->clk_rate / SPI_MBR_DIV_MAX;
+	master->setup = stm32_spi_setup;
+	master->prepare_message = stm32_spi_prepare_msg;
+	master->transfer_one = stm32_spi_transfer_one;
+	master->unprepare_message = stm32_spi_unprepare_msg;
+
+	spi->dma_tx = dma_request_slave_channel(spi->dev, "tx");
+	if (!spi->dma_tx)
+		dev_warn(&pdev->dev, "failed to request tx dma channel\n");
+	else
+		master->dma_tx = spi->dma_tx;
+
+	spi->dma_rx = dma_request_slave_channel(spi->dev, "rx");
+	if (!spi->dma_rx)
+		dev_warn(&pdev->dev, "failed to request rx dma channel\n");
+	else
+		master->dma_rx = spi->dma_rx;
+
+	if (spi->dma_tx || spi->dma_rx)
+		master->can_dma = stm32_spi_can_dma;
+
+	ret = devm_spi_register_master(&pdev->dev, master);
+	if (ret) {
+		dev_err(&pdev->dev, "spi master registration failed: %d\n",
+			ret);
+		goto err_dma_release;
+	}
+
+	if (!master->cs_gpios) {
+		dev_err(&pdev->dev, "no CS gpios available\n");
+		ret = -EINVAL;
+		goto err_dma_release;
+	}
+
+	for (i = 0; i < master->num_chipselect; i++) {
+		if (!gpio_is_valid(master->cs_gpios[i])) {
+			dev_err(&pdev->dev, "%i is not a valid gpio\n",
+				master->cs_gpios[i]);
+			ret = -EINVAL;
+			goto err_dma_release;
+		}
+
+		ret = devm_gpio_request(&pdev->dev, master->cs_gpios[i],
+					DRIVER_NAME);
+		if (ret) {
+			dev_err(&pdev->dev, "can't get CS gpio %i\n",
+				master->cs_gpios[i]);
+			goto err_dma_release;
+		}
+	}
+
+	dev_info(&pdev->dev, "driver initialized\n");
+
+	return 0;
+
+err_dma_release:
+	if (spi->dma_tx)
+		dma_release_channel(spi->dma_tx);
+	if (spi->dma_rx)
+		dma_release_channel(spi->dma_rx);
+err_clk_disable:
+	clk_disable_unprepare(spi->clk);
+err_master_put:
+	spi_master_put(master);
+
+	return ret;
+}
+
+static int stm32_spi_remove(struct platform_device *pdev)
+{
+	struct spi_master *master = platform_get_drvdata(pdev);
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+
+	stm32_spi_disable(spi);
+
+	if (master->dma_tx)
+		dma_release_channel(master->dma_tx);
+	if (master->dma_rx)
+		dma_release_channel(master->dma_rx);
+
+	clk_disable_unprepare(spi->clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int stm32_spi_suspend(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+	int ret;
+
+	ret = spi_master_suspend(master);
+	if (ret)
+		return ret;
+
+	clk_disable_unprepare(spi->clk);
+
+	return ret;
+}
+
+static int stm32_spi_resume(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+	int ret;
+
+	ret = clk_prepare_enable(spi->clk);
+	if (ret)
+		return ret;
+	ret = spi_master_resume(master);
+	if (ret)
+		clk_disable_unprepare(spi->clk);
+
+	return ret;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(stm32_spi_pm_ops,
+			 stm32_spi_suspend, stm32_spi_resume);
+
+static struct platform_driver stm32_spi_driver = {
+	.probe = stm32_spi_probe,
+	.remove = stm32_spi_remove,
+	.driver = {
+		.name = DRIVER_NAME,
+		.pm = &stm32_spi_pm_ops,
+		.of_match_table = stm32_spi_of_match,
+	},
+};
+
+module_platform_driver(stm32_spi_driver);
+
+MODULE_ALIAS("platform:" DRIVER_NAME);
+MODULE_DESCRIPTION("STMicroelectronics STM32 SPI Controller driver");
+MODULE_AUTHOR("Amelie Delaunay <amelie.delaunay@xxxxxx>");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1