Subject: [PATCH v3 5/5] mtd: atmel-quadspi: add driver for Atmel QSPI controller

From: [email-masked] (Nicolas Ferre)
Date: Fri, 31 Jul 2015 10:51:25 +0200

Le 27/07/2015 10:59, Cyrille Pitchen a ?crit :
> This driver add support to the new Atmel QSPI controller embedded into
> sama5d2x SoCs. It expects a NOR memory to be connected to the QSPI
> controller.
> 
> Signed-off-by: Cyrille Pitchen <[email-masked]>
> ---
>  drivers/mtd/spi-nor/Kconfig         |   7 +
>  drivers/mtd/spi-nor/Makefile        |   1 +
>  drivers/mtd/spi-nor/atmel-quadspi.c | 877 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 885 insertions(+)
>  create mode 100644 drivers/mtd/spi-nor/atmel-quadspi.c
> 
> diff --git a/drivers/mtd/spi-nor/Kconfig b/drivers/mtd/spi-nor/Kconfig
> index 64a4f0edabc7..bcdda302f5ab 100644
> --- a/drivers/mtd/spi-nor/Kconfig
> +++ b/drivers/mtd/spi-nor/Kconfig
> @@ -28,4 +28,11 @@ config SPI_FSL_QUADSPI
>  	  This enables support for the Quad SPI controller in master mode.
>  	  We only connect the NOR to this controller now.
>  
> +config SPI_ATMEL_QUADSPI
> +	tristate "Atmel Quad SPI Controller"
> +	depends on (ARCH_AT91 || COMPILE_TEST)

Don't we need an additional:
        depends on HAS_DMA

to handle the COMPILE_TEST case? Otherwise it could break on some
configurations.

> +	help
> +	  This enables support for the Quad SPI controller in master mode.
> +	  We only connect the NOR to this controller now.
> +
>  endif # MTD_SPI_NOR
> diff --git a/drivers/mtd/spi-nor/Makefile b/drivers/mtd/spi-nor/Makefile
> index 6a7ce1462247..243ea8a479ef 100644
> --- a/drivers/mtd/spi-nor/Makefile
> +++ b/drivers/mtd/spi-nor/Makefile
> @@ -1,2 +1,3 @@
>  obj-$(CONFIG_MTD_SPI_NOR)	+= spi-nor.o
>  obj-$(CONFIG_SPI_FSL_QUADSPI)	+= fsl-quadspi.o
> +obj-$(CONFIG_SPI_ATMEL_QUADSPI)	+= atmel-quadspi.o
> diff --git a/drivers/mtd/spi-nor/atmel-quadspi.c b/drivers/mtd/spi-nor/atmel-quadspi.c
> new file mode 100644
> index 000000000000..20dccd660b3c
> --- /dev/null
> +++ b/drivers/mtd/spi-nor/atmel-quadspi.c
> @@ -0,0 +1,877 @@
> +/*
> + * Driver for Atmel QSPI Controller
> + *
> + * Copyright (C) 2015 Atmel Corporation
> + *
> + * Author: Cyrille Pitchen <[email-masked]>
> + *
> + * This program 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.
> + *
> + * This program is distributed in the hope that it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program.  If not, see <http://www.gnu.org/licenses/>.
> + *
> + * This driver is based on drivers/mtd/spi-nor/fsl-quadspi.c from Freescale.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/clk.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/delay.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/dmaengine.h>
> +#include <linux/err.h>
> +#include <linux/interrupt.h>
> +#include <linux/mtd/mtd.h>
> +#include <linux/mtd/partitions.h>
> +#include <linux/mtd/spi-nor.h>
> +#include <linux/platform_data/atmel.h>
> +#include <linux/platform_data/dma-atmel.h>
> +#include <linux/of.h>
> +
> +#include <linux/io.h>
> +#include <linux/gpio.h>
> +#include <linux/pinctrl/consumer.h>
> +
> +/* QSPI register offsets */
> +#define QSPI_CR      0x0000  /* Control Register */
> +#define QSPI_MR      0x0004  /* Mode Register */
> +#define QSPI_RD      0x0008  /* Receive Data Register */
> +#define QSPI_TD      0x000c  /* Transmit Data Register */
> +#define QSPI_SR      0x0010  /* Status Register */
> +#define QSPI_IER     0x0014  /* Interrupt Enable Register */
> +#define QSPI_IDR     0x0018  /* Interrupt Disable Register */
> +#define QSPI_IMR     0x001c  /* Interrupt Mask Register */
> +#define QSPI_SCR     0x0020  /* Serial Clock Register */
> +
> +#define QSPI_IAR     0x0030  /* Instruction Address Register */
> +#define QSPI_ICR     0x0034  /* Instruction Code Register */
> +#define QSPI_IFR     0x0038  /* Instruction Frame Register */
> +
> +#define QSPI_SMR     0x0040  /* Scrambling Mode Register */
> +#define QSPI_SKR     0x0044  /* Scrambling Key Register */
> +
> +#define QSPI_WPMR    0x00E4  /* Write Protection Mode Register */
> +#define QSPI_WPSR    0x00E8  /* Write Protection Status Register */
> +
> +#define QSPI_VERSION 0x00FC  /* Version Register */
> +
> +
> +/* Bitfields in QSPI_CR (Control Register) */
> +#define QSPI_CR_QSPIEN                  BIT(0)
> +#define QSPI_CR_QSPIDIS                 BIT(1)
> +#define QSPI_CR_SWRST                   BIT(7)
> +#define QSPI_CR_LASTXFER                BIT(24)
> +
> +/* Bitfields in QSPI_MR (Mode Register) */
> +#define QSPI_MR_SSM                     BIT(0)
> +#define QSPI_MR_LLB                     BIT(1)
> +#define QSPI_MR_WDRBT                   BIT(2)
> +#define QSPI_MR_SMRM                    BIT(3)
> +#define QSPI_MR_CSMODE_MASK             GENMASK(5, 4)
> +#define QSPI_MR_CSMODE_NOT_RELOADED     (0 << 4)
> +#define QSPI_MR_CSMODE_LASTXFER         (1 << 4)
> +#define QSPI_MR_CSMODE_SYSTEMATICALLY   (2 << 4)
> +#define QSPI_MR_NBBITS_MASK             GENMASK(11, 8)
> +#define QSPI_MR_NBBITS(n)               ((((n) - 8) << 8) & QSPI_MR_NBBITS_MASK)
> +#define QSPI_MR_DLYBCT_MASK             GENMASK(23, 16)
> +#define QSPI_MR_DLYBCT(n)               (((n) << 16) & QSPI_MR_DLYBCT_MASK)
> +#define QSPI_MR_DLYCS_MASK              GENMASK(31, 24)
> +#define QSPI_MR_DLYCS(n)                (((n) << 24) & QSPI_MR_DLYCS_MASK)
> +
> +/* Bitfields in QSPI_SR/QSPI_IER/QSPI_IDR/QSPI_IMR  */
> +#define QSPI_SR_RDRF                    BIT(0)
> +#define QSPI_SR_TDRE                    BIT(1)
> +#define QSPI_SR_TXEMPTY                 BIT(2)
> +#define QSPI_SR_OVRES                   BIT(3)
> +#define QSPI_SR_CSR                     BIT(8)
> +#define QSPI_SR_CSS                     BIT(9)
> +#define QSPI_SR_INSTRE                  BIT(10)
> +#define QSPI_SR_QSPIENS                 BIT(24)
> +
> +/* Bitfields in QSPI_SCR (Serial Clock Register) */
> +#define QSPI_SCR_CPOL                   BIT(0)
> +#define QSPI_SCR_CPHA                   BIT(1)
> +#define QSPI_SCR_SCBR_MASK              GENMASK(15, 8)
> +#define QSPI_SCR_SCBR(n)                (((n) << 8) & QSPI_SCR_SCBR_MASK)
> +#define QSPI_SCR_DLYBS_MASK             GENMASK(23, 16)
> +#define QSPI_SCR_DLYBS(n)               (((n) << 16) & QSPI_SCR_DLYBS_MASK)
> +
> +/* Bitfields in QSPI_ICR (Instruction Code Register) */
> +#define QSPI_ICR_INST_MASK              GENMASK(7, 0)
> +#define QSPI_ICR_INST(inst)             (((inst) << 0) & QSPI_ICR_INST_MASK)
> +#define QSPI_ICR_OPT_MASK               GENMASK(23, 16)
> +#define QSPI_ICR_OPT(opt)               (((opt) << 16) & QSPI_ICR_OPT_MASK)
> +
> +/* Bitfields in QSPI_IFR (Instruction Frame Register) */
> +#define QSPI_IFR_WIDTH_MASK             GENMASK(2, 0)
> +#define QSPI_IFR_WIDTH_SINGLE_BIT_SPI   (0 << 0)
> +#define QSPI_IFR_WIDTH_DUAL_OUTPUT      (1 << 0)
> +#define QSPI_IFR_WIDTH_QUAD_OUTPUT      (2 << 0)
> +#define QSPI_IFR_WIDTH_DUAL_IO          (3 << 0)
> +#define QSPI_IFR_WIDTH_QUAD_IO          (4 << 0)
> +#define QSPI_IFR_WIDTH_DUAL_CMD         (5 << 0)
> +#define QSPI_IFR_WIDTH_QUAD_CMD         (6 << 0)
> +#define QSPI_IFR_INSTEN                 BIT(4)
> +#define QSPI_IFR_ADDREN                 BIT(5)
> +#define QSPI_IFR_OPTEN                  BIT(6)
> +#define QSPI_IFR_DATAEN                 BIT(7)
> +#define QSPI_IFR_OPTL_MASK              GENMASK(9, 8)
> +#define QSPI_IFR_OPTL_1BIT              (0 << 8)
> +#define QSPI_IFR_OPTL_2BIT              (1 << 8)
> +#define QSPI_IFR_OPTL_4BIT              (2 << 8)
> +#define QSPI_IFR_OPTL_8BIT              (3 << 8)
> +#define QSPI_IFR_ADDRL                  BIT(10)
> +#define QSPI_IFR_TFRTYP_MASK            GENMASK(13, 12)
> +#define QSPI_IFR_TFRTYP_TRSFR_READ      (0 << 12)
> +#define QSPI_IFR_TFRTYP_TRSFR_READ_MEM  (1 << 12)
> +#define QSPI_IFR_TFRTYP_TRSFR_WRITE     (2 << 12)
> +#define QSPI_IFR_TFRTYP_TRSFR_WRITE_MEM (3 << 13)
> +#define QSPI_IFR_CRM                    BIT(14)
> +#define QSPI_IFR_NBDUM_MASK             GENMASK(20, 16)
> +#define QSPI_IFR_NBDUM(n)               (((n) << 16) & QSPI_IFR_NBDUM_MASK)
> +
> +/* Bitfields in QSPI_SMR (Scrambling Mode Register) */
> +#define QSPI_SMR_SCREN                  BIT(0)
> +#define QSPI_SMR_RVDIS                  BIT(1)
> +
> +/* Bitfields in QSPI_WPMR (Write Protection Mode Register) */
> +#define QSPI_WPMR_WPEN                  BIT(0)
> +#define QSPI_WPMR_WPKEY_MASK            GENMASK(31, 8)
> +#define QSPI_WPMR_WPKEY(wpkey)          (((wpkey) << 8) & QSPI_WPMR_WPKEY_MASK)
> +
> +/* Bitfields in QSPI_WPSR (Write Protection Status Register) */
> +#define QSPI_WPSR_WPVS                  BIT(0)
> +#define QSPI_WPSR_WPVSRC_MASK           GENMASK(15, 8)
> +#define QSPI_WPSR_WPVSRC(src)           (((src) << 8) & QSPI_WPSR_WPVSRC)
> +
> +
> +struct atmel_qspi {
> +	void __iomem		*regs;
> +	void __iomem		*mem;
> +	dma_addr_t		phys_addr;
> +	struct dma_chan		*chan;
> +	struct clk		*clk;
> +	struct platform_device	*pdev;
> +	u32			ifr_width;
> +	u32			pending;
> +
> +	struct mtd_info		mtd;
> +	struct spi_nor		nor;
> +	u32			clk_rate;
> +	struct completion	completion;
> +
> +#ifdef DEBUG
> +	u8			last_instruction;
> +#endif
> +};
> +
> +struct atmel_qspi_command {
> +	u32	ifr_tfrtyp;
> +	union {
> +		struct {
> +			u32	instruction:1;
> +			u32	address:3;
> +			u32	mode:1;
> +			u32	dummy:1;
> +			u32	data:1;
> +			u32	dma:1;
> +			u32	reserved:24;
> +		}		bits;
> +		u32	word;
> +	}	enable;
> +	u8	instruction;
> +	u8	mode;
> +	u8	num_mode_cycles;
> +	u8	num_dummy_cycles;
> +	u32	address;
> +
> +	size_t		buf_len;
> +	const void	*tx_buf;
> +	void		*rx_buf;
> +};
> +
> +/* Register access macros */
> +static inline u32 qspi_readl(struct atmel_qspi *aq, u32 reg)
> +{
> +	return readl_relaxed(aq->regs + reg);
> +}
> +
> +static inline void qspi_writel(struct atmel_qspi *aq, u32 reg, u32 value)
> +{
> +	writel_relaxed(value, aq->regs + reg);
> +}
> +
> +static inline u16 qspi_readw(struct atmel_qspi *aq, u32 reg)
> +{
> +	return readw_relaxed(aq->regs + reg);
> +}
> +
> +static inline void qspi_writew(struct atmel_qspi *aq, u32 reg, u16 value)
> +{
> +	writew_relaxed(value, aq->regs + reg);
> +}
> +
> +static inline u8 qspi_readb(struct atmel_qspi *aq, u32 reg)
> +{
> +	return readb_relaxed(aq->regs + reg);
> +}
> +
> +static inline void qspi_writeb(struct atmel_qspi *aq, u32 reg, u8 value)
> +{
> +	writeb_relaxed(value, aq->regs + reg);
> +}
> +
> +
> +#define QSPI_DMA_THRESHOLD	32
> +
> +static void atmel_qspi_dma_callback(void *arg)
> +{
> +	struct completion *c = arg;
> +
> +	complete(c);
> +}
> +
> +static int atmel_qspi_run_dma_transfer(struct atmel_qspi *aq,
> +				       const struct atmel_qspi_command *cmd)
> +{
> +	u32 offset = (cmd->enable.bits.address) ? cmd->address : 0;
> +	struct dma_chan *chan = aq->chan;
> +	struct device *dev = &aq->pdev->dev;
> +	enum dma_data_direction direction;
> +	dma_addr_t phys_addr, dst, src;
> +	struct dma_async_tx_descriptor *desc;
> +	struct completion completion;
> +	dma_cookie_t cookie;
> +	int err = 0;
> +
> +	if (cmd->tx_buf) {
> +		direction = DMA_TO_DEVICE;
> +		phys_addr = dma_map_single(dev, (void *)cmd->tx_buf,
> +					   cmd->buf_len, direction);
> +		src = phys_addr;
> +		dst = aq->phys_addr + offset;
> +	} else {
> +		direction = DMA_FROM_DEVICE;
> +		phys_addr = dma_map_single(dev, (void *)cmd->rx_buf,
> +					   cmd->buf_len, direction);
> +		src = aq->phys_addr + offset;
> +		dst = phys_addr;
> +	}
> +	err = dma_mapping_error(dev, phys_addr);

This function seems to return a boolean....

> +	if (err)
> +		goto exit;

... and I'm not sure that propagating this boolean value is what you
want here and in the calling functions: please double check this.

> +
> +	desc = chan->device->device_prep_dma_memcpy(chan, dst, src,
> +						    cmd->buf_len,
> +						    DMA_PREP_INTERRUPT);
> +	if (!desc) {
> +		err = -ENOMEM;
> +		goto unmap_single;
> +	}
> +
> +	init_completion(&completion);
> +	desc->callback = atmel_qspi_dma_callback;
> +	desc->callback_param = &completion;
> +	cookie = dmaengine_submit(desc);
> +	err = dma_submit_error(cookie);
> +	if (err)
> +		goto unmap_single;
> +	dma_async_issue_pending(chan);
> +
> +	if (!wait_for_completion_timeout(&completion, msecs_to_jiffies(1000)))
> +		err = -ETIMEDOUT;
> +
> +	if (dma_async_is_tx_complete(chan, cookie, NULL, NULL) != DMA_COMPLETE)
> +		err = -ETIMEDOUT;
> +
> +	if (err)
> +		dmaengine_terminate_all(chan);
> +unmap_single:
> +	dma_unmap_single(dev, phys_addr, cmd->buf_len, direction);
> +exit:
> +	return err;
> +}
> +
> +static int atmel_qspi_run_transfer(struct atmel_qspi *aq,
> +				   const struct atmel_qspi_command *cmd)
> +{
> +	void __iomem *ahb_mem;
> +
> +	/* First try a DMA transfer */
> +	if (aq->chan && cmd->enable.bits.dma &&
> +	    cmd->buf_len >= QSPI_DMA_THRESHOLD)
> +		return atmel_qspi_run_dma_transfer(aq, cmd);
> +
> +	/* Then fallback to a PIO transfer */
> +	ahb_mem = aq->mem;
> +	if (cmd->enable.bits.address)
> +		ahb_mem += cmd->address;
> +	if (cmd->tx_buf)
> +		memcpy_toio(ahb_mem, cmd->tx_buf, cmd->buf_len);
> +	else
> +		memcpy_fromio(cmd->rx_buf, ahb_mem, cmd->buf_len);
> +
> +	return 0;
> +}
> +
> +#ifdef DEBUG
> +static void atmel_qspi_debug_command(struct atmel_qspi *aq,
> +				     const struct atmel_qspi_command *cmd)
> +{
> +	u8 cmd_buf[SPI_NOR_MAX_CMD_SIZE];
> +	size_t len = 0;
> +	int i;
> +
> +	if (cmd->enable.bits.instruction) {
> +		if (aq->last_instruction == cmd->instruction)
> +			return;
> +		aq->last_instruction = cmd->instruction;
> +	}
> +
> +	if (cmd->enable.bits.instruction)
> +		cmd_buf[len++] = cmd->instruction;
> +
> +	for (i = cmd->enable.bits.address-1; i >= 0; --i)
> +		cmd_buf[len++] = (cmd->address >> (i << 3)) & 0xff;
> +
> +	if (cmd->enable.bits.mode)
> +		cmd_buf[len++] = cmd->mode;
> +
> +	if (cmd->enable.bits.dummy) {
> +		int num = cmd->num_dummy_cycles;
> +
> +		switch (aq->ifr_width) {
> +		case QSPI_IFR_WIDTH_SINGLE_BIT_SPI:
> +		case QSPI_IFR_WIDTH_DUAL_OUTPUT:
> +		case QSPI_IFR_WIDTH_QUAD_OUTPUT:
> +			num >>= 3;
> +			break;
> +		case QSPI_IFR_WIDTH_DUAL_IO:
> +		case QSPI_IFR_WIDTH_DUAL_CMD:
> +			num >>= 2;
> +			break;
> +		case QSPI_IFR_WIDTH_QUAD_IO:
> +		case QSPI_IFR_WIDTH_QUAD_CMD:
> +			num >>= 1;
> +			break;
> +		default:
> +			return;
> +		}
> +
> +		for (i = 0; i < num; ++i)
> +			cmd_buf[len++] = 0;
> +	}
> +
> +	/* Dump the SPI command */
> +	print_hex_dump(KERN_DEBUG, "qspi cmd: ", DUMP_PREFIX_NONE,
> +		       32, 1, cmd_buf, len, false);
> +
> +#ifdef VERBOSE_DEBUG
> +	/* If verbose debug is enabled, also dump the TX data */
> +	if (cmd->enable.bits.data && cmd->tx_buf)
> +		print_hex_dump(KERN_DEBUG, "qspi tx : ", DUMP_PREFIX_NONE,
> +			       32, 1, cmd->tx_buf, cmd->buf_len, false);
> +#endif
> +}
> +#else
> +#define atmel_qspi_debug_command(aq, cmd)
> +#endif
> +
> +static int atmel_qspi_run_command(struct atmel_qspi *aq,
> +				  const struct atmel_qspi_command *cmd)
> +{
> +	u32 iar, icr, ifr, sr;
> +	int err = 0;
> +
> +	iar = 0;
> +	icr = 0;
> +	ifr = aq->ifr_width | cmd->ifr_tfrtyp;
> +
> +	/* Compute instruction parameters */
> +	if (cmd->enable.bits.instruction) {
> +		icr |= QSPI_ICR_INST(cmd->instruction);
> +		ifr |= QSPI_IFR_INSTEN;
> +	}
> +
> +	/* Compute address parameters */
> +	switch (cmd->enable.bits.address) {
> +	case 4:
> +		ifr |= QSPI_IFR_ADDRL;
> +		/*break;*/ /* fallback to the 24bit address case */
> +	case 3:
> +		iar = (cmd->enable.bits.data) ? 0 : cmd->address;
> +		ifr |= QSPI_IFR_ADDREN;
> +		break;
> +	case 0:
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	/* Compute option parameters */
> +	if (cmd->enable.bits.mode && cmd->num_mode_cycles) {
> +		u32 mode_cycle_bits, mode_bits;
> +
> +		icr |= QSPI_ICR_OPT(cmd->mode);
> +		ifr |= QSPI_IFR_OPTEN;
> +
> +		switch (ifr & QSPI_IFR_WIDTH_MASK) {
> +		case QSPI_IFR_WIDTH_SINGLE_BIT_SPI:
> +		case QSPI_IFR_WIDTH_DUAL_OUTPUT:
> +		case QSPI_IFR_WIDTH_QUAD_OUTPUT:
> +			mode_cycle_bits = 1;
> +			break;
> +		case QSPI_IFR_WIDTH_DUAL_IO:
> +		case QSPI_IFR_WIDTH_DUAL_CMD:
> +			mode_cycle_bits = 2;
> +			break;
> +		case QSPI_IFR_WIDTH_QUAD_IO:
> +		case QSPI_IFR_WIDTH_QUAD_CMD:
> +			mode_cycle_bits = 4;
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +
> +		mode_bits = cmd->num_mode_cycles * mode_cycle_bits;
> +		switch (mode_bits) {
> +		case 1:
> +			ifr |= QSPI_IFR_OPTL_1BIT;
> +			break;
> +
> +		case 2:
> +			ifr |= QSPI_IFR_OPTL_2BIT;
> +			break;
> +
> +		case 4:
> +			ifr |= QSPI_IFR_OPTL_4BIT;
> +			break;
> +
> +		case 8:
> +			ifr |= QSPI_IFR_OPTL_8BIT;
> +			break;
> +
> +		default:
> +			return -EINVAL;
> +		}
> +	}
> +
> +	/* Set number of dummy cycles */
> +	if (cmd->enable.bits.dummy)
> +		ifr |= QSPI_IFR_NBDUM(cmd->num_dummy_cycles);
> +
> +	/* Set data enable */
> +	if (cmd->enable.bits.data) {
> +		ifr |= QSPI_IFR_DATAEN;
> +
> +		/* Special case for Continuous Read Mode */
> +		if (!cmd->tx_buf && !cmd->rx_buf)
> +			ifr |= QSPI_IFR_CRM;
> +	}
> +
> +	/* Set QSPI Instruction Frame registers */
> +	atmel_qspi_debug_command(aq, cmd);
> +	qspi_writel(aq, QSPI_IAR, iar);
> +	qspi_writel(aq, QSPI_ICR, icr);
> +	qspi_writel(aq, QSPI_IFR, ifr);
> +
> +	/* Skip to the final steps if there is no data */
> +	if (!cmd->enable.bits.data)
> +		goto no_data;
> +
> +	/* Dummy read of QSPI_IFR to synchronize APB and AHB accesses */
> +	(void)qspi_readl(aq, QSPI_IFR);
> +
> +	/* Stop here for continuous read */
> +	if (!cmd->tx_buf && !cmd->rx_buf)
> +		return 0;
> +	/* Send/Receive data */
> +	err = atmel_qspi_run_transfer(aq, cmd);
> +
> +	/* Release the chip-select */
> +	qspi_writel(aq, QSPI_CR, QSPI_CR_LASTXFER);
> +
> +	if (err)
> +		return err;
> +
> +#if defined(DEBUG) && defined(VERBOSE_DEBUG)
> +	/*
> +	 * If verbose debug is enabled, also dump the RX data in addition to
> +	 * the SPI command previously dumped by atmel_qspi_debug_command()
> +	 */
> +	if (cmd->rx_buf)
> +		print_hex_dump(KERN_DEBUG, "qspi rx : ", DUMP_PREFIX_NONE,
> +			       32, 1, cmd->rx_buf, cmd->buf_len, false);
> +#endif
> +no_data:
> +	/* Poll INSTRuction End status */
> +	sr = qspi_readl(aq, QSPI_SR);
> +	if (sr & QSPI_SR_INSTRE)
> +		return err;
> +
> +	/* Wait for INSTRuction End interrupt */
> +	init_completion(&aq->completion);
> +	aq->pending = 0;
> +	qspi_writel(aq, QSPI_IER, QSPI_SR_INSTRE);
> +	if (!wait_for_completion_timeout(&aq->completion,
> +					 msecs_to_jiffies(1000)))
> +		err = -ETIMEDOUT;
> +	qspi_writel(aq, QSPI_IDR, QSPI_SR_INSTRE);
> +
> +	return err;
> +}
> +
> +static int atmel_qspi_read_reg(struct spi_nor *nor, u8 opcode,
> +			       u8 *buf, int len)
> +{
> +	struct atmel_qspi *aq = nor->priv;
> +	struct atmel_qspi_command cmd;
> +
> +	memset(&cmd, 0, sizeof(cmd));
> +	cmd.ifr_tfrtyp = QSPI_IFR_TFRTYP_TRSFR_READ;
> +	cmd.enable.bits.instruction = 1;
> +	cmd.enable.bits.data = 1;
> +	cmd.instruction = opcode;
> +	cmd.rx_buf = buf;
> +	cmd.buf_len = len;
> +	return atmel_qspi_run_command(aq, &cmd);
> +}
> +
> +static int atmel_qspi_write_reg(struct spi_nor *nor, u8 opcode,
> +				u8 *buf, int len,
> +				int write_enable)
> +{
> +	struct atmel_qspi *aq = nor->priv;
> +	struct atmel_qspi_command cmd;
> +
> +	memset(&cmd, 0, sizeof(cmd));
> +	cmd.ifr_tfrtyp = QSPI_IFR_TFRTYP_TRSFR_WRITE;
> +	cmd.enable.bits.instruction = 1;
> +	cmd.enable.bits.data = (buf != NULL && len > 0);
> +	cmd.instruction = opcode;
> +	cmd.tx_buf = buf;
> +	cmd.buf_len = len;
> +	return atmel_qspi_run_command(aq, &cmd);
> +}
> +
> +static void atmel_qspi_write(struct spi_nor *nor, loff_t to, size_t len,
> +			     size_t *retlen, const u_char *write_buf)
> +{
> +	struct atmel_qspi *aq = nor->priv;
> +	struct atmel_qspi_command cmd;
> +
> +	memset(&cmd, 0, sizeof(cmd));
> +	cmd.ifr_tfrtyp = QSPI_IFR_TFRTYP_TRSFR_WRITE_MEM;
> +	cmd.enable.bits.instruction = 1;
> +	cmd.enable.bits.address = nor->addr_width;
> +	cmd.enable.bits.data = 1;
> +	cmd.enable.bits.dma = 1;
> +	cmd.instruction = nor->program_opcode;
> +	cmd.address = (u32)to;
> +	cmd.tx_buf = write_buf;
> +	cmd.buf_len = len;
> +	if (!atmel_qspi_run_command(aq, &cmd))
> +		*retlen += len;
> +}
> +
> +static int atmel_qspi_erase(struct spi_nor *nor, loff_t offs)
> +{
> +	struct atmel_qspi *aq = nor->priv;
> +	struct atmel_qspi_command cmd;
> +
> +	dev_dbg(nor->dev, "%dKiB at 0x%08x\n",
> +		aq->mtd.erasesize / 1024, (u32)offs);
> +
> +	memset(&cmd, 0, sizeof(cmd));
> +	cmd.ifr_tfrtyp = QSPI_IFR_TFRTYP_TRSFR_WRITE;
> +	cmd.enable.bits.instruction = 1;
> +	cmd.enable.bits.address = nor->addr_width;
> +	cmd.instruction = nor->erase_opcode;
> +	cmd.address = (u32)offs;
> +	return atmel_qspi_run_command(aq, &cmd);
> +}
> +
> +static int atmel_qspi_read(struct spi_nor *nor, loff_t from, size_t len,
> +			   size_t *retlen, u_char *read_buf)
> +{
> +	struct atmel_qspi *aq = nor->priv;
> +	struct atmel_qspi_command cmd;
> +	int err;
> +
> +	memset(&cmd, 0, sizeof(cmd));
> +	cmd.ifr_tfrtyp = QSPI_IFR_TFRTYP_TRSFR_READ_MEM;
> +	cmd.enable.bits.instruction = 1;
> +	cmd.enable.bits.address = nor->addr_width;
> +	cmd.enable.bits.dummy = (nor->read_dummy > 0);
> +	cmd.enable.bits.data = 1;
> +	cmd.enable.bits.dma = 1;
> +	cmd.instruction = nor->read_opcode;
> +	cmd.address = (u32)from;
> +	cmd.num_dummy_cycles = nor->read_dummy;
> +	cmd.rx_buf = read_buf;
> +	cmd.buf_len = len;
> +	err = atmel_qspi_run_command(aq, &cmd);
> +	if (err)
> +		return err;
> +
> +	*retlen += len;
> +	return 0;
> +}
> +
> +static int atmel_qspi_set_protocol(struct spi_nor *nor, enum spi_protocol proto)
> +{
> +	struct atmel_qspi *aq = nor->priv;
> +
> +	switch (proto) {
> +	case SPI_PROTO_1_1_1:
> +		aq->ifr_width = QSPI_IFR_WIDTH_SINGLE_BIT_SPI;
> +		break;
> +	case SPI_PROTO_1_1_2:
> +		aq->ifr_width = QSPI_IFR_WIDTH_DUAL_OUTPUT;
> +		break;
> +	case SPI_PROTO_1_1_4:
> +		aq->ifr_width = QSPI_IFR_WIDTH_QUAD_OUTPUT;
> +		break;
> +	case SPI_PROTO_1_2_2:
> +		aq->ifr_width = QSPI_IFR_WIDTH_DUAL_IO;
> +		break;
> +	case SPI_PROTO_1_4_4:
> +		aq->ifr_width = QSPI_IFR_WIDTH_QUAD_IO;
> +		break;
> +	case SPI_PROTO_2_2_2:
> +		aq->ifr_width = QSPI_IFR_WIDTH_DUAL_CMD;
> +		break;
> +	case SPI_PROTO_4_4_4:
> +		aq->ifr_width = QSPI_IFR_WIDTH_QUAD_CMD;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static int atmel_qspi_init(struct atmel_qspi *aq)
> +{
> +	unsigned long src_rate;
> +	u32 mr, scr, scbr;
> +
> +	/* Reset the QSPI controller */
> +	qspi_writel(aq, QSPI_CR, QSPI_CR_SWRST);
> +
> +	/* Set the QSPI controller in Serial Memory Mode */
> +	mr = QSPI_MR_SSM | QSPI_MR_NBBITS(8);
> +	qspi_writel(aq, QSPI_MR, mr);
> +
> +	src_rate = clk_get_rate(aq->clk);
> +	if (!src_rate)
> +		return -EINVAL;
> +
> +	/* Compute the QSPI baudrate */
> +	scbr = DIV_ROUND_UP(src_rate, aq->clk_rate);
> +	if (scbr > 0)
> +		scbr--;
> +	scr = QSPI_SCR_SCBR(scbr);
> +	qspi_writel(aq, QSPI_SCR, scr);
> +
> +	/* Enable the QSPI controller */
> +	qspi_writel(aq, QSPI_CR, QSPI_CR_QSPIEN);
> +
> +	return 0;
> +}
> +
> +static irqreturn_t atmel_qspi_interrupt(int irq, void *dev_id)
> +{
> +	struct atmel_qspi *aq = (struct atmel_qspi *)dev_id;
> +	u32 status, mask, pending;
> +
> +	status = qspi_readl(aq, QSPI_SR);
> +	mask = qspi_readl(aq, QSPI_IMR);
> +	pending = status & mask;
> +
> +	if (!pending)
> +		return IRQ_NONE;
> +
> +	aq->pending |= pending;
> +	if (pending & QSPI_SR_INSTRE)
> +		complete(&aq->completion);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int atmel_qspi_probe(struct platform_device *pdev)
> +{
> +	struct device_node *child, *np = pdev->dev.of_node;
> +	struct mtd_part_parser_data ppdata;
> +	struct atmel_qspi *aq;
> +	struct resource *res;
> +	dma_cap_mask_t mask;
> +	struct spi_nor *nor;
> +	struct mtd_info *mtd;
> +	char modalias[40];
> +	int irq, err = 0;
> +
> +	if (of_get_child_count(np) != 1)
> +		return -ENODEV;
> +	child = of_get_next_child(np, NULL);
> +
> +	aq = devm_kzalloc(&pdev->dev, sizeof(*aq), GFP_KERNEL);
> +	if (!aq) {
> +		err = -ENOMEM;
> +		goto exit;
> +	}
> +
> +	platform_set_drvdata(pdev, aq);
> +	aq->pdev = pdev;
> +	/* Start in Extended SPI (1-1-1) */
> +	aq->ifr_width = QSPI_IFR_WIDTH_SINGLE_BIT_SPI;
> +
> +	/* Map the registers */
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	aq->regs = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(aq->regs)) {
> +		dev_err(&pdev->dev, "missing registers\n");
> +		err = PTR_ERR(aq->regs);
> +		goto exit;
> +	}
> +
> +	/* Map the AHB memory */
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> +	aq->mem = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(aq->mem)) {
> +		dev_err(&pdev->dev, "missing AHB memory\n");
> +		err = PTR_ERR(aq->regs);
> +		goto exit;
> +	}
> +	aq->phys_addr = (dma_addr_t)res->start;
> +
> +	/* Get the peripheral clock */
> +	aq->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(aq->clk)) {
> +		dev_err(&pdev->dev, "missing peripheral clock\n");
> +		err = PTR_ERR(aq->clk);
> +		goto exit;
> +	}
> +
> +	/* Enable the peripheral clock */
> +	err = clk_prepare_enable(aq->clk);
> +	if (err) {
> +		dev_err(&pdev->dev, "failed to enable the peripheral clock\n");
> +		goto exit;
> +	}
> +
> +	/* Request the IRQ */
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0) {
> +		dev_err(&pdev->dev, "missing IRQ\n");
> +		err = irq;
> +		goto disable_clk;
> +	}
> +	err = devm_request_irq(&pdev->dev, irq, atmel_qspi_interrupt,
> +			       0, dev_name(&pdev->dev), aq);
> +	if (err)
> +		goto disable_clk;
> +
> +	/* Try to get a DMA channel for memcpy() operation */
> +	dma_cap_zero(mask);
> +	dma_cap_set(DMA_MEMCPY, mask);
> +	aq->chan = dma_request_channel(mask, NULL, NULL);
> +	if (!aq->chan)
> +		dev_warn(&pdev->dev, "no available DMA channel\n");
> +
> +	/* Setup the spi-nor */
> +	nor = &aq->nor;
> +	mtd = &aq->mtd;
> +
> +	nor->mtd = mtd;
> +	nor->dev = &pdev->dev;
> +	nor->priv = aq;
> +	mtd->priv = nor;
> +
> +	nor->read_reg = atmel_qspi_read_reg;
> +	nor->write_reg = atmel_qspi_write_reg;
> +	nor->read = atmel_qspi_read;
> +	nor->write = atmel_qspi_write;
> +	nor->erase = atmel_qspi_erase;
> +	nor->set_protocol = atmel_qspi_set_protocol;
> +
> +	if (of_modalias_node(child, modalias, sizeof(modalias)) < 0) {
> +		err = -ENODEV;
> +		goto release_channel;
> +	}
> +
> +	err = of_property_read_u32(child, "spi-max-frequency", &aq->clk_rate);
> +	if (err < 0)
> +		goto release_channel;
> +
> +	err = atmel_qspi_init(aq);
> +	if (err)
> +		goto release_channel;
> +
> +	nor->dev->of_node = child;
> +	err = spi_nor_scan(nor, modalias, SPI_NOR_QUAD);
> +	nor->dev->of_node = np;
> +	if (err)
> +		goto release_channel;
> +
> +	ppdata.of_node = child;
> +	err = mtd_device_parse_register(mtd, NULL, &ppdata, NULL, 0);
> +	if (err)
> +		goto release_channel;
> +
> +	of_node_put(child);
> +
> +	return 0;
> +
> +release_channel:
> +	if (aq->chan)
> +		dma_release_channel(aq->chan);
> +disable_clk:
> +	clk_disable_unprepare(aq->clk);
> +exit:
> +	of_node_put(child);
> +
> +	return err;
> +}
> +
> +static int atmel_qspi_remove(struct platform_device *pdev)
> +{
> +	struct atmel_qspi *aq = platform_get_drvdata(pdev);
> +
> +	mtd_device_unregister(&aq->mtd);
> +	qspi_writel(aq, QSPI_CR, QSPI_CR_QSPIDIS);
> +	if (aq->chan)
> +		dma_release_channel(aq->chan);
> +	clk_disable_unprepare(aq->clk);
> +	return 0;
> +}
> +
> +
> +static const struct of_device_id atmel_qspi_dt_ids[] = {
> +	{ .compatible = "atmel,sama5d2-qspi" },
> +	{ /* sentinel */ }
> +};
> +
> +MODULE_DEVICE_TABLE(of, atmel_qspi_dt_ids);
> +
> +static struct platform_driver atmel_qspi_driver = {
> +	.driver = {
> +		.name	= "atmel_qspi",
> +		.of_match_table	= atmel_qspi_dt_ids,
> +	},
> +	.probe		= atmel_qspi_probe,
> +	.remove		= atmel_qspi_remove,
> +};
> +module_platform_driver(atmel_qspi_driver);
> +
> +MODULE_AUTHOR("Cyrille Pitchen <[email-masked]>");
> +MODULE_DESCRIPTION("Atmel QSPI Controller driver");
> +MODULE_LICENSE("GPL v2");

Otherwise, once checked my comments above, you can add my:
Acked-by: Nicolas Ferre <[email-masked]>

Thanks, bye,
-- 
Nicolas Ferre