Re: [PATCH v2 1/2] spi: add support for DLN-2 USB-SPI adapter

[Johan Havold <johan@xxxxxxxxxx>]

On Wed, Nov 12, 2014 at 03:38:09PM +0200, Laurentiu Palcu wrote:
> This adds support for Diolan DLN2 USB-SPI adapter.
> 
> Information about the USB protocol interface can be found in the
> Programmer's Reference Manual [1], see section 5.4.6 for the SPI
> master module commands and responses.
> 
> [1] https://www.diolan.com/downloads/dln-api-manual.pdf
> 
> Signed-off-by: Laurentiu Palcu <laurentiu.palcu@xxxxxxxxx>
> ---
>  drivers/spi/Kconfig    |  10 +
>  drivers/spi/Makefile   |   1 +
>  drivers/spi/spi-dln2.c | 793 +++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 804 insertions(+)
>  create mode 100644 drivers/spi/spi-dln2.c
> 
> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
> index 62e2242..a52a910 100644
> --- a/drivers/spi/Kconfig
> +++ b/drivers/spi/Kconfig
> @@ -176,6 +176,16 @@ config SPI_DAVINCI
>  	help
>  	  SPI master controller for DaVinci/DA8x/OMAP-L/AM1x SPI modules.
>  
> +config SPI_DLN2
> +       tristate "Diolan DLN-2 USB SPI adapter"
> +       depends on MFD_DLN2
> +       help
> +         If you say yes to this option, support will be included for Diolan
> +         DLN2, a USB to SPI interface.
> +
> +         This driver can also be built as a module.  If so, the module
> +         will be called spi-dln2.
> +
>  config SPI_EFM32
>  	tristate "EFM32 SPI controller"
>  	depends on OF && ARM && (ARCH_EFM32 || COMPILE_TEST)
> diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
> index 762da07..b315da2 100644
> --- a/drivers/spi/Makefile
> +++ b/drivers/spi/Makefile
> @@ -26,6 +26,7 @@ obj-$(CONFIG_SPI_CADENCE)		+= spi-cadence.o
>  obj-$(CONFIG_SPI_CLPS711X)		+= spi-clps711x.o
>  obj-$(CONFIG_SPI_COLDFIRE_QSPI)		+= spi-coldfire-qspi.o
>  obj-$(CONFIG_SPI_DAVINCI)		+= spi-davinci.o
> +obj-$(CONFIG_SPI_DLN2)			+= spi-dln2.o
>  obj-$(CONFIG_SPI_DESIGNWARE)		+= spi-dw.o
>  obj-$(CONFIG_SPI_DW_MMIO)		+= spi-dw-mmio.o
>  obj-$(CONFIG_SPI_DW_PCI)		+= spi-dw-midpci.o
> diff --git a/drivers/spi/spi-dln2.c b/drivers/spi/spi-dln2.c
> new file mode 100644
> index 0000000..8277294
> --- /dev/null
> +++ b/drivers/spi/spi-dln2.c
> @@ -0,0 +1,793 @@
> +/*
> + * Driver for the Diolan DLN-2 USB-SPI adapter
> + *
> + * Copyright (c) 2014 Intel Corporation
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation, version 2.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/mfd/dln2.h>
> +#include <linux/spi/spi.h>
> +
> +#define DLN2_SPI_MODULE_ID		0x02
> +#define DLN2_SPI_CMD(cmd)		DLN2_CMD(cmd, DLN2_SPI_MODULE_ID)
> +
> +/* SPI commands */
> +#define DLN2_SPI_GET_PORT_COUNT			DLN2_SPI_CMD(0x00)
> +#define DLN2_SPI_ENABLE				DLN2_SPI_CMD(0x11)
> +#define DLN2_SPI_DISABLE			DLN2_SPI_CMD(0x12)
> +#define DLN2_SPI_IS_ENABLED			DLN2_SPI_CMD(0x13)
> +#define DLN2_SPI_SET_MODE			DLN2_SPI_CMD(0x14)
> +#define DLN2_SPI_GET_MODE			DLN2_SPI_CMD(0x15)
> +#define DLN2_SPI_SET_FRAME_SIZE			DLN2_SPI_CMD(0x16)
> +#define DLN2_SPI_GET_FRAME_SIZE			DLN2_SPI_CMD(0x17)
> +#define DLN2_SPI_SET_FREQUENCY			DLN2_SPI_CMD(0x18)
> +#define DLN2_SPI_GET_FREQUENCY			DLN2_SPI_CMD(0x19)
> +#define DLN2_SPI_READ_WRITE			DLN2_SPI_CMD(0x1A)
> +#define DLN2_SPI_READ				DLN2_SPI_CMD(0x1B)
> +#define DLN2_SPI_WRITE				DLN2_SPI_CMD(0x1C)
> +#define DLN2_SPI_SET_DELAY_BETWEEN_SS		DLN2_SPI_CMD(0x20)
> +#define DLN2_SPI_GET_DELAY_BETWEEN_SS		DLN2_SPI_CMD(0x21)
> +#define DLN2_SPI_SET_DELAY_AFTER_SS		DLN2_SPI_CMD(0x22)
> +#define DLN2_SPI_GET_DELAY_AFTER_SS		DLN2_SPI_CMD(0x23)
> +#define DLN2_SPI_SET_DELAY_BETWEEN_FRAMES	DLN2_SPI_CMD(0x24)
> +#define DLN2_SPI_GET_DELAY_BETWEEN_FRAMES	DLN2_SPI_CMD(0x25)
> +#define DLN2_SPI_SET_SS				DLN2_SPI_CMD(0x26)
> +#define DLN2_SPI_GET_SS				DLN2_SPI_CMD(0x27)
> +#define DLN2_SPI_RELEASE_SS			DLN2_SPI_CMD(0x28)
> +#define DLN2_SPI_SS_VARIABLE_ENABLE		DLN2_SPI_CMD(0x2B)
> +#define DLN2_SPI_SS_VARIABLE_DISABLE		DLN2_SPI_CMD(0x2C)
> +#define DLN2_SPI_SS_VARIABLE_IS_ENABLED		DLN2_SPI_CMD(0x2D)
> +#define DLN2_SPI_SS_AAT_ENABLE			DLN2_SPI_CMD(0x2E)
> +#define DLN2_SPI_SS_AAT_DISABLE			DLN2_SPI_CMD(0x2F)
> +#define DLN2_SPI_SS_AAT_IS_ENABLED		DLN2_SPI_CMD(0x30)
> +#define DLN2_SPI_SS_BETWEEN_FRAMES_ENABLE	DLN2_SPI_CMD(0x31)
> +#define DLN2_SPI_SS_BETWEEN_FRAMES_DISABLE	DLN2_SPI_CMD(0x32)
> +#define DLN2_SPI_SS_BETWEEN_FRAMES_IS_ENABLED	DLN2_SPI_CMD(0x33)
> +#define DLN2_SPI_SET_CPHA			DLN2_SPI_CMD(0x34)
> +#define DLN2_SPI_GET_CPHA			DLN2_SPI_CMD(0x35)
> +#define DLN2_SPI_SET_CPOL			DLN2_SPI_CMD(0x36)
> +#define DLN2_SPI_GET_CPOL			DLN2_SPI_CMD(0x37)
> +#define DLN2_SPI_SS_MULTI_ENABLE		DLN2_SPI_CMD(0x38)
> +#define DLN2_SPI_SS_MULTI_DISABLE		DLN2_SPI_CMD(0x39)
> +#define DLN2_SPI_SS_MULTI_IS_ENABLED		DLN2_SPI_CMD(0x3A)
> +#define DLN2_SPI_GET_SUPPORTED_MODES		DLN2_SPI_CMD(0x40)
> +#define DLN2_SPI_GET_SUPPORTED_CPHA_VALUES	DLN2_SPI_CMD(0x41)
> +#define DLN2_SPI_GET_SUPPORTED_CPOL_VALUES	DLN2_SPI_CMD(0x42)
> +#define DLN2_SPI_GET_SUPPORTED_FRAME_SIZES	DLN2_SPI_CMD(0x43)
> +#define DLN2_SPI_GET_SS_COUNT			DLN2_SPI_CMD(0x44)
> +#define DLN2_SPI_GET_MIN_FREQUENCY		DLN2_SPI_CMD(0x45)
> +#define DLN2_SPI_GET_MAX_FREQUENCY		DLN2_SPI_CMD(0x46)
> +#define DLN2_SPI_GET_MIN_DELAY_BETWEEN_SS	DLN2_SPI_CMD(0x47)
> +#define DLN2_SPI_GET_MAX_DELAY_BETWEEN_SS	DLN2_SPI_CMD(0x48)
> +#define DLN2_SPI_GET_MIN_DELAY_AFTER_SS		DLN2_SPI_CMD(0x49)
> +#define DLN2_SPI_GET_MAX_DELAY_AFTER_SS		DLN2_SPI_CMD(0x4A)
> +#define DLN2_SPI_GET_MIN_DELAY_BETWEEN_FRAMES	DLN2_SPI_CMD(0x4B)
> +#define DLN2_SPI_GET_MAX_DELAY_BETWEEN_FRAMES	DLN2_SPI_CMD(0x4C)
> +
> +#define DLN2_SPI_MAX_XFER_SIZE			256
> +#define DLN2_SPI_BUF_SIZE			(DLN2_SPI_MAX_XFER_SIZE + 16)
> +#define DLN2_SPI_ATTR_LEAVE_SS_LOW		BIT(0)
> +#define DLN2_TRANSFERS_WAIT_COMPLETE		1
> +#define DLN2_TRANSFERS_CANCEL			0
> +
> +struct dln2_spi {
> +	struct platform_device *pdev;
> +	struct spi_master *master;
> +	u8 port;
> +
> +	void *buf;

Add comment on what is protecting this buffer.

> +
> +	u8 bpw;
> +	u32 speed;
> +	u16 mode;
> +	u8 cs;
> +};
> +
> +/*
> + * Enable/Disable SPI module. The disable command will wait for transfers to
> + * complete first.
> + */
> +static int dln2_spi_enable(struct dln2_spi *dln2, bool enable)
> +{
> +	int ret;
> +	u16 cmd;
> +	struct {
> +		u8 port;
> +		u8 wait_for_completion;
> +	} __packed tx;

No need for __packed.

> +	unsigned len = sizeof(tx);
> +
> +	tx.port = dln2->port;
> +
> +	if (enable) {
> +		cmd = DLN2_SPI_ENABLE;
> +		len -= sizeof(tx.wait_for_completion);
> +	} else {
> +		tx.wait_for_completion = DLN2_TRANSFERS_WAIT_COMPLETE;
> +		cmd = DLN2_SPI_DISABLE;
> +	}
> +
> +	ret = dln2_transfer_tx(dln2->pdev, cmd, &tx, len);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +/*
> + * Select/unselect multiple CS lines. The selected lines will be automatically
> + * toggled LOW/HIGH by the board firmware during transfers, provided they're
> + * enabled first.
> + *
> + * Ex: cs_mask = 0x03 -> CS0 & CS1 will be selected and the next WR/RD operation

Seems you have several comments that wrap at >80 columns (81 above).

> + *                       will toggle the lines LOW/HIGH automatically.
> + */
> +static int dln2_spi_cs_set(struct dln2_spi *dln2, u8 cs_mask)
> +{
> +	struct {
> +		u8 port;
> +		u8 cs;
> +	} __packed tx;
> +

No __packed.

> +	tx.port = dln2->port;
> +
> +	/* According to Diolan docs, "a slave device can be selected by changing
> +	 * the corresponding bit value to 0". The rest must be set to 1. Hence
> +	 * the bitwise NOT in front.
> +	 */
> +	tx.cs = ~cs_mask;
> +
> +	return dln2_transfer_tx(dln2->pdev, DLN2_SPI_SET_SS, &tx, sizeof(tx));
> +}
> +
> +/*
> + * Select one CS line. The other lines will be un-selected.
> + */
> +static int dln2_spi_cs_set_one(struct dln2_spi *dln2, u8 cs)
> +{
> +	return dln2_spi_cs_set(dln2, BIT(cs));
> +}
> +
> +/*
> + * Enable/disable CS lines for usage. The module has to be disabled first.
> + */
> +static int dln2_spi_cs_enable(struct dln2_spi *dln2, u8 cs_mask, bool enable)
> +{
> +	struct {
> +		u8 port;
> +		u8 cs;
> +	} __packed tx;

No __packed.

> +	u16 cmd;
> +
> +	tx.port = dln2->port;
> +	tx.cs = cs_mask;
> +	cmd = enable ? DLN2_SPI_SS_MULTI_ENABLE : DLN2_SPI_SS_MULTI_DISABLE;
> +
> +	return dln2_transfer_tx(dln2->pdev, cmd, &tx, sizeof(tx));
> +}
> +
> +static int dln2_spi_cs_enable_all(struct dln2_spi *dln2, bool enable)
> +{
> +	u8 cs_mask = GENMASK(dln2->master->num_chipselect - 1, 0);
> +
> +	return dln2_spi_cs_enable(dln2, cs_mask, enable);
> +}
> +
> +static int dln2_spi_get_cs_num(struct dln2_spi *dln2, u16 *cs_num)
> +{
> +	int ret;
> +	struct {
> +		u8 port;
> +	} tx;
> +	struct {
> +		__le16 cs_count;
> +	} *rx = dln2->buf;

I don't think you want to use dln2->buf for all these small transfers.
And what would be protecting it from concurrent use?

Check this throughout.

> +	unsigned rx_len = sizeof(*rx);
> +
> +	tx.port = dln2->port;
> +	ret = dln2_transfer(dln2->pdev, DLN2_SPI_GET_SS_COUNT, &tx, sizeof(tx),
> +			    rx, &rx_len);
> +	if (ret < 0)
> +		return ret;
> +	if (rx_len < sizeof(*rx))
> +		return -EPROTO;
> +
> +	*cs_num = le16_to_cpu(rx->cs_count);
> +
> +	dev_dbg(&dln2->pdev->dev, "cs_num = %d\n", *cs_num);

Use the spi device for device messages throughout.

> +
> +	return 0;
> +}
> +
> +/*
> + * Get bus min/max frequencies.
> + */
> +static int dln2_spi_get_speed_range(struct dln2_spi *dln2, u32 *fmin, u32 *fmax)
> +{
> +	int ret;
> +	struct {
> +		u8 port;
> +	} tx;
> +	struct {
> +		__le32 speed;
> +	} *rx = dln2->buf;
> +	unsigned rx_len = sizeof(*rx);
> +	int cmd[2] = {DLN2_SPI_GET_MIN_FREQUENCY, DLN2_SPI_GET_MAX_FREQUENCY};
> +	u32 *speed[2] = {fmin, fmax};

Spaces after and before { and }.

> +	int i;
> +
> +	tx.port = dln2->port;
> +
> +	for (i = 0; i < 2; i++) {
> +		ret = dln2_transfer(dln2->pdev, cmd[i], &tx, sizeof(tx),
> +				    rx, &rx_len);
> +		if (ret < 0)
> +			return ret;
> +		if (rx_len < sizeof(*rx))
> +			return -EPROTO;
> +
> +		*speed[i] = le32_to_cpu(rx->speed);
> +	}

Add a helper to fetch a 32-bit value and call it twice instead of the
loop-construct above.

> +
> +	dev_dbg(&dln2->pdev->dev, "freq_min = %d, freq_max = %d\n",
> +		*fmin, *fmax);
> +
> +	return 0;
> +}
> +
> +/*
> + * Set the bus speed. The module will automatically round down to the closest
> + * available frequency and returns it. The module has to be disabled first.
> + */
> +static int dln2_spi_set_speed(struct dln2_spi *dln2, u32 speed,
> +			      u32 *probed_speed)
> +{
> +	int ret;
> +	struct {
> +		u8 port;
> +		__le32 speed;
> +	} __packed tx;
> +	struct {
> +		__le32 speed;
> +	} __packed *rx = dln2->buf;
> +	int rx_len = sizeof(*rx);
> +
> +	tx.port = dln2->port;
> +	tx.speed = cpu_to_le32(speed);
> +
> +	ret = dln2_transfer(dln2->pdev, DLN2_SPI_SET_FREQUENCY, &tx, sizeof(tx),
> +			    rx, &rx_len);
> +	if (ret < 0)
> +		return ret;
> +	if (rx_len < sizeof(*rx))
> +		return -EPROTO;
> +
> +	if (probed_speed)
> +		*probed_speed = le32_to_cpu(rx->speed);

You never use the probed_speed parameter in any call to this function.
Remove it if you don't need it.

> +
> +	return 0;
> +}
> +
> +/*
> + * Change CPOL & CPHA. The module has to be disabled first.
> + */
> +static int dln2_spi_set_mode(struct dln2_spi *dln2, u8 mode)
> +{
> +	struct {
> +		u8 port;
> +		u8 mode;
> +	} __packed tx;

No __packed.

> +
> +	tx.port = dln2->port;
> +	tx.mode = mode;
> +
> +	return dln2_transfer_tx(dln2->pdev, DLN2_SPI_SET_MODE, &tx, sizeof(tx));
> +}
> +
> +/*
> + * Change frame size. The module has to be disabled first.
> + */
> +static int dln2_spi_set_bpw(struct dln2_spi *dln2, u8 bpw)
> +{
> +	struct {
> +		u8 port;
> +		u8 bpw;
> +	} __packed tx;

Ditto.

> +
> +	tx.port = dln2->port;
> +	tx.bpw = bpw;
> +
> +	return dln2_transfer_tx(dln2->pdev, DLN2_SPI_SET_FRAME_SIZE,
> +				&tx, sizeof(tx));
> +}
> +
> +static int dln2_spi_get_supported_frame_sizes(struct dln2_spi *dln2,
> +					      u32 *bpw_mask)
> +{
> +	int ret;
> +	struct {
> +		u8 port;
> +	} tx;
> +	struct {
> +		u8 count;
> +		u8 frame_sizes[36];
> +	} __packed *rx = dln2->buf;
> +	unsigned rx_len = sizeof(*rx);
> +	int i;
> +
> +	tx.port = dln2->port;
> +
> +	ret = dln2_transfer(dln2->pdev, DLN2_SPI_GET_SUPPORTED_FRAME_SIZES,
> +			    &tx, sizeof(tx), rx, &rx_len);
> +	if (ret < 0)
> +		return ret;
> +	if (rx_len  < sizeof(*rx))
> +		return -EPROTO;
> +

You must verify rx->count.

> +	*bpw_mask = 0;
> +	for (i = 0; i < rx->count; i++)
> +		*bpw_mask |= BIT(rx->frame_sizes[i] - 1);
> +
> +	dev_dbg(&dln2->pdev->dev, "bpw_mask = 0x%X\n", *bpw_mask);
> +
> +	return 0;
> +}
> +
> +/*
> + * Copy the data to DLN2 buffer and change the alignment to LE, requested by
> + * DLN2 module. SPI core makes sure that the data length is a multiple of word
> + * size.

What about buffer alignment?

> + */
> +static int dln2_spi_copy_to_buf(u8 *dln2_buf, const u8 *src, u16 len, u8 bpw)
> +{
> +#ifdef __LITTLE_ENDIAN
> +	memcpy(dln2_buf, src, len);
> +#else
> +	if (bpw <= 8)
> +		memcpy(dln2_buf, src, len);

Missing braces.

> +	else if (bpw <= 16) {
> +		__le16 *d = (__le16 *) dln2_buf;

No spaces after casts.

> +		u16 *s = (u16 *) src;
> +
> +		len = len / 2;
> +		while (len--)
> +			*d++ = cpu_to_le16p(s++);
> +	} else {
> +		__le32 *d = (__le32 *) dln2_buf;
> +		u32 *s = (u32 *) src;
> +
> +		len = len / 4;
> +		while (len--)
> +			*d++ = cpu_to_le32p(s++);
> +	}
> +#endif
> +
> +	return 0;
> +}
> +
> +/*
> + * Copy the data from DLN2 buffer and convert to CPU alignment since the DLN2
> + * buffer is LE aligned. SPI core makes sure that the data length is a multiple
> + * of word size.
> + */
> +static int dln2_spi_copy_from_buf(u8 *dest, const u8 *dln2_buf, u16 len, u8 bpw)
> +{
> +#ifdef __LITTLE_ENDIAN
> +	memcpy(dest, dln2_buf, len);
> +#else
> +	if (bpw <= 8)
> +		memcpy(dest, dln2_buf, len);
> +	else if (bpw <= 16) {
> +		u16 *d = (u16 *) dest;
> +		__le16 *s = (__le16 *) dln2_buf;
> +
> +		len = len / 2;
> +		while (len--)
> +			*d++ = le16_to_cpup(s++);
> +	} else {
> +		u32 *d = (u32 *) dest;
> +		__le32 *s = (__le32 *) dln2_buf;
> +
> +		len = len / 4;
> +		while (len--)
> +			*d++ = le32_to_cpup(s++);
> +	}
> +#endif
> +
> +	return 0;
> +}
> +
> +/*
> + * Perform one write operation.
> + */
> +static int dln2_spi_write_one(struct dln2_spi *dln2, const u8 *data,
> +			      u16 data_len, u8 attr)
> +{
> +	struct {
> +		u8 port;
> +		__le16 size;
> +		u8 attr;
> +		u8 buf[DLN2_SPI_MAX_XFER_SIZE];
> +	} __packed *tx = dln2->buf;
> +	unsigned tx_len;
> +
> +	BUILD_BUG_ON(sizeof(*tx) > DLN2_SPI_BUF_SIZE);
> +
> +	if (data_len > DLN2_SPI_MAX_XFER_SIZE)
> +		return -EINVAL;
> +
> +	tx->port = dln2->port;
> +	tx->size = cpu_to_le16(data_len);
> +	tx->attr = attr;
> +
> +	dln2_spi_copy_to_buf(tx->buf, data, data_len, dln2->bpw);
> +
> +	tx_len = sizeof(*tx) + data_len - DLN2_SPI_MAX_XFER_SIZE;
> +	return dln2_transfer_tx(dln2->pdev, DLN2_SPI_WRITE, tx, tx_len);
> +}
> +
> +/*
> + * Perform one read operation.
> + */
> +static int dln2_spi_read_one(struct dln2_spi *dln2, u8 *data,
> +			     u16 data_len, u8 attr)
> +{
> +	int ret;
> +	struct {
> +		u8 port;
> +		__le16 size;
> +		u8 attr;
> +	} __packed tx;
> +	struct {
> +		__le16 size;
> +		u8 buf[DLN2_SPI_MAX_XFER_SIZE];
> +	} __packed *rx = dln2->buf;
> +	unsigned rx_len = sizeof(*rx);
> +
> +	BUILD_BUG_ON(sizeof(*rx) > DLN2_SPI_BUF_SIZE);
> +
> +	if (data_len > DLN2_SPI_MAX_XFER_SIZE)
> +		return -EINVAL;
> +
> +	tx.port = dln2->port;
> +	tx.size = cpu_to_le16(data_len);
> +	tx.attr = attr;
> +
> +	ret = dln2_transfer(dln2->pdev, DLN2_SPI_READ, &tx, sizeof(tx),
> +			    rx, &rx_len);
> +	if (ret < 0)
> +		return ret;
> +	if (rx_len < sizeof(rx->size) + data_len)
> +		return -EPROTO;
> +	if (le16_to_cpu(rx->size) != data_len)
> +		return -EPROTO;
> +
> +	dln2_spi_copy_from_buf(data, rx->buf, data_len, dln2->bpw);
> +
> +	return 0;
> +}
> +
> +/*
> + * Perform one write & read operation.
> + */
> +static int dln2_spi_read_write_one(struct dln2_spi *dln2, const u8 *tx_data,
> +				   u8 *rx_data, u16 data_len, u8 attr)
> +{
> +	int ret;
> +	struct {
> +		u8 port;
> +		__le16 size;
> +		u8 attr;
> +		u8 buf[DLN2_SPI_MAX_XFER_SIZE];
> +	} __packed *tx;
> +	struct {
> +		__le16 size;
> +		u8 buf[DLN2_SPI_MAX_XFER_SIZE];
> +	} __packed *rx;
> +	unsigned tx_len, rx_len;
> +
> +	BUILD_BUG_ON(sizeof(*tx) > DLN2_SPI_BUF_SIZE ||
> +		     sizeof(*rx) > DLN2_SPI_BUF_SIZE);
> +
> +	if (data_len > DLN2_SPI_MAX_XFER_SIZE)
> +		return -EINVAL;
> +
> +	/* Since this is a pseudo full-duplex communication, we're perfectly
> +	 * safe to use the same buffer for both tx and rx. When DLN2 sends the
> +	 * response back, with the rx data, we don't need the tx buffer anymore.
> +	 */
> +	tx = dln2->buf;
> +	rx = dln2->buf;
> +
> +	tx->port = dln2->port;
> +	tx->size = cpu_to_le16(data_len);
> +	tx->attr = attr;
> +
> +	dln2_spi_copy_to_buf(tx->buf, tx_data, data_len, dln2->bpw);
> +
> +	tx_len = sizeof(*tx) + data_len - DLN2_SPI_MAX_XFER_SIZE;
> +	rx_len = sizeof(*rx);
> +
> +	ret = dln2_transfer(dln2->pdev, DLN2_SPI_READ_WRITE, tx, tx_len,
> +			    rx, &rx_len);
> +	if (ret < 0)
> +		return ret;
> +	if (rx_len < sizeof(rx->size) + data_len)
> +		return -EPROTO;
> +	if (le16_to_cpu(rx->size) != data_len)
> +		return -EPROTO;
> +
> +	dln2_spi_copy_from_buf(rx_data, rx->buf, data_len, dln2->bpw);
> +
> +	return 0;
> +}
> +
> +/*
> + * Read/Write wrapper. It will automatically split an operation into multiple
> + * single ones due to device buffer constraints.
> + */
> +static int dln2_spi_rdwr(struct dln2_spi *dln2, const u8 *tx_data,
> +			 u8 *rx_data, u16 data_len, u8 attr) {
> +	int ret;
> +	u16 len;
> +	u8 temp_attr;
> +	u16 remaining = data_len;
> +	u16 offset;
> +
> +	do {
> +		if (remaining > DLN2_SPI_MAX_XFER_SIZE) {
> +			len = DLN2_SPI_MAX_XFER_SIZE;
> +			temp_attr = DLN2_SPI_ATTR_LEAVE_SS_LOW;
> +		} else {
> +			len = remaining;
> +			temp_attr = attr;
> +		}
> +
> +		offset = data_len - remaining;
> +
> +		if (tx_data && rx_data)
> +			ret = dln2_spi_read_write_one(dln2,
> +						      tx_data + offset,
> +						      rx_data + offset,
> +						      len, temp_attr);
> +		else if (tx_data)
> +			ret = dln2_spi_write_one(dln2,
> +						 tx_data + offset,
> +						 len, temp_attr);
> +		else if (rx_data)
> +			ret = dln2_spi_read_one(dln2,
> +						rx_data + offset,
> +						len, temp_attr);
> +		else
> +			return -EINVAL;

Braces, please.

> +
> +		if (ret < 0)
> +			return ret;
> +
> +		remaining -= len;
> +	} while (remaining);
> +
> +	return 0;
> +}
> +
> +static int dln2_spi_prepare_message(struct spi_master *master,
> +				    struct spi_message *message)
> +{
> +	int ret;
> +	struct dln2_spi *dln2 = spi_master_get_devdata(master);
> +	struct spi_device *spi = message->spi;
> +
> +	if (dln2->cs != spi->chip_select) {
> +		ret = dln2_spi_cs_set_one(dln2, spi->chip_select);
> +		if (ret < 0)
> +			return ret;
> +
> +		dln2->cs = spi->chip_select;
> +	}
> +
> +	return 0;
> +}
> +
> +static int dln2_spi_transfer_setup(struct dln2_spi *dln2, u32 speed,
> +				   u8 bpw, u8 mode)
> +{
> +	int ret;
> +	bool bus_setup_change;
> +
> +	bus_setup_change = dln2->speed != speed || dln2->mode != mode ||
> +			   dln2->bpw != bpw;
> +
> +	if (!bus_setup_change)
> +		return 0;
> +
> +	ret = dln2_spi_enable(dln2, false);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (dln2->speed != speed) {
> +		ret = dln2_spi_set_speed(dln2, speed, NULL);
> +		if (ret < 0)
> +			return ret;
> +
> +		dln2->speed = speed;
> +	}
> +
> +	if (dln2->mode != mode) {
> +		ret = dln2_spi_set_mode(dln2, mode & 0x3);
> +		if (ret < 0)
> +			return ret;
> +
> +		dln2->mode = mode;
> +	}
> +
> +	if (dln2->bpw != bpw) {
> +		ret = dln2_spi_set_bpw(dln2, bpw);
> +		if (ret < 0)
> +			return ret;
> +
> +		dln2->bpw = bpw;
> +	}
> +
> +	ret = dln2_spi_enable(dln2, true);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int dln2_spi_transfer_one_message(struct spi_master *master,
> +					 struct spi_message *msg)
> +{
> +	struct dln2_spi *dln2 = spi_master_get_devdata(master);
> +	struct spi_device *spi = msg->spi;
> +	struct spi_transfer *xfer;
> +	int status;
> +
> +	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
> +		u8 attr = 0;
> +
> +		status = dln2_spi_transfer_setup(dln2, xfer->speed_hz,
> +						 xfer->bits_per_word,
> +						 spi->mode);
> +		if (status < 0) {
> +			dev_err(&dln2->pdev->dev, "Cannot setup transfer\n");
> +			break;
> +		}
> +
> +		if (!xfer->cs_change &&
> +		    !list_is_last(&xfer->transfer_list, &msg->transfers))
> +			attr = xfer->cs_change ? 0 : DLN2_SPI_ATTR_LEAVE_SS_LOW;
> +
> +		status = dln2_spi_rdwr(dln2, xfer->tx_buf, xfer->rx_buf,
> +				       xfer->len, attr);
> +		if (status < 0) {
> +			dev_err(&dln2->pdev->dev, "write/read failed!\n");
> +			break;
> +		}
> +
> +		status = 0;
> +	}
> +
> +	msg->status = status;
> +	spi_finalize_current_message(master);
> +	return status;
> +}
> +
> +static int dln2_spi_probe(struct platform_device *pdev)
> +{
> +	struct spi_master *master;
> +	struct dln2_spi *dln2;
> +	struct dln2_platform_data *pdata = dev_get_platdata(&pdev->dev);
> +	int ret;
> +
> +	master = spi_alloc_master(&pdev->dev, sizeof(*dln2));
> +	if (!master)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, master);
> +
> +	dln2 = spi_master_get_devdata(master);
> +
> +	dln2->buf = devm_kmalloc(&pdev->dev, DLN2_SPI_BUF_SIZE, GFP_KERNEL);
> +	if (!dln2->buf) {
> +		ret = -ENOMEM;
> +		goto exit_free_master;
> +	}
> +
> +	dln2->master = master;
> +	dln2->pdev = pdev;
> +	dln2->port = pdata->port;
> +	/* cs number can never be 0xff, so the first transfer will set the cs */
> +	dln2->cs = 0xff;
> +
> +	/* disable SPI module before continuing with the setup */
> +	ret = dln2_spi_enable(dln2, false);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "Failed to disable SPI module\n");
> +		goto exit_free_master;
> +	}
> +
> +	ret = dln2_spi_get_cs_num(dln2, &master->num_chipselect);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "Failed to get number of CS pins\n");
> +		goto exit_free_master;
> +	}
> +
> +	ret = dln2_spi_get_speed_range(dln2,
> +				       &master->min_speed_hz,
> +				       &master->max_speed_hz);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "Failed to read bus min/max freqs\n");
> +		goto exit_free_master;
> +	}
> +
> +	ret = dln2_spi_get_supported_frame_sizes(dln2,
> +						 &master->bits_per_word_mask);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "Failed to read supported frame sizes\n");
> +		goto exit_free_master;
> +	}
> +
> +	ret = dln2_spi_cs_enable_all(dln2, true);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "Failed to enable CS pins\n");
> +		goto exit_free_master;
> +	}
> +
> +	master->bus_num = -1;
> +	master->mode_bits = SPI_CPOL | SPI_CPHA;
> +	master->prepare_message = dln2_spi_prepare_message;
> +	master->transfer_one_message = dln2_spi_transfer_one_message;
> +
> +	/* enable SPI module, we're good to go */
> +	ret = dln2_spi_enable(dln2, true);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "Failed to enable SPI module\n");
> +		goto exit_free_master;
> +	}
> +
> +	ret = devm_spi_register_master(&pdev->dev, master);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "Failed to register master\n");
> +		goto exit_register;
> +	}
> +
> +	return ret;
> +
> +exit_register:
> +	if (dln2_spi_enable(dln2, false) < 0)
> +		dev_err(&pdev->dev, "Failed to disable SPI module\n");
> +exit_free_master:
> +	spi_master_put(master);
> +
> +	return ret;
> +}
> +
> +static int dln2_spi_remove(struct platform_device *pdev)
> +{
> +	struct spi_master *master = spi_master_get(platform_get_drvdata(pdev));
> +	struct dln2_spi *dln2 = spi_master_get_devdata(master);
> +
> +	if (dln2_spi_enable(dln2, false) < 0)
> +		dev_err(&pdev->dev, "Failed to disable SPI module\n");
> +

Memory leak -- spi_master_put missing.

> +	return 0;
> +}
> +
> +static struct platform_driver spi_dln2_driver = {
> +	.driver.name	= "dln2-spi",
> +	.probe		= dln2_spi_probe,
> +	.remove		= dln2_spi_remove,
> +};
> +module_platform_driver(spi_dln2_driver);
> +
> +MODULE_DESCRIPTION("Driver for the Diolan DLN2 SPI master interface");
> +MODULE_AUTHOR("Laurentiu Palcu <laurentiu.palcu@xxxxxxxxx>");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:dln2-spi");

Johan
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