Unverified Commit 6c613f68 authored by Alexandru Ardelean's avatar Alexandru Ardelean Committed by Mark Brown
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spi: core,atmel: convert `word_delay_usecs` -> `word_delay` for spi_device 



This change does a conversion from the `word_delay_usecs` -> `word_delay`
for the `spi_device` struct.

This allows users to specify inter-word delays in other unit types
(nano-seconds or clock cycles), depending on how users want.

The Atmel SPI driver is the only current user of the `word_delay_usecs`
field (from the `spi_device` struct).
So, it needed a slight conversion to use the `word_delay` as an `spi_delay`
struct.

In SPI core, the only required mechanism is to update the `word_delay`
information per `spi_transfer`. This requires a bit more logic than before,
because it needs that both delays be converted to a common unit
(nano-seconds) for comparison.

Signed-off-by: default avatarAlexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20190926105147.7839-8-alexandru.ardelean@analog.com


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent ec3fa72f

drivers/spi/spi-atmel.c

+24 −2
Original line number Diff line number Diff line
@@ -1149,12 +1149,31 @@ atmel_spi_pdc_interrupt(int irq, void *dev_id) 
	return ret;

}



static int atmel_word_delay_csr(struct spi_device *spi, struct atmel_spi *as)

{

	struct spi_delay *delay = &spi->word_delay;

	u32 value = delay->value;



	switch (delay->unit) {

	case SPI_DELAY_UNIT_NSECS:

		value /= 1000;

		break;

	case SPI_DELAY_UNIT_USECS:

		break;

	default:

		return -EINVAL;

	}



	return (as->spi_clk / 1000000 * value) >> 5;

}



static int atmel_spi_setup(struct spi_device *spi)

{

	struct atmel_spi	*as;

	struct atmel_spi_device	*asd;

	u32			csr;

	unsigned int		bits = spi->bits_per_word;

	int			word_delay_csr;



	as = spi_master_get_devdata(spi->master);
@@ -1178,11 +1197,14 @@ static int atmel_spi_setup(struct spi_device *spi) 
	 */

	csr |= SPI_BF(DLYBS, 0);



	word_delay_csr = atmel_word_delay_csr(spi, as);

	if (word_delay_csr < 0)

		return word_delay_csr;



	/* DLYBCT adds delays between words.  This is useful for slow devices

	 * that need a bit of time to setup the next transfer.

	 */

	csr |= SPI_BF(DLYBCT,

			(as->spi_clk / 1000000 * spi->word_delay_usecs) >> 5);

	csr |= SPI_BF(DLYBCT, word_delay_csr);



	asd = spi->controller_state;

	if (!asd) {

drivers/spi/spi.c

+22 −2
Original line number Diff line number Diff line
@@ -3281,6 +3281,26 @@ void spi_set_cs_timing(struct spi_device *spi, u8 setup, u8 hold, 
}

EXPORT_SYMBOL_GPL(spi_set_cs_timing);



static int _spi_xfer_word_delay_update(struct spi_transfer *xfer,

				       struct spi_device *spi)

{

	int delay1, delay2;



	delay1 = _spi_delay_to_ns(&xfer->word_delay, xfer);

	if (delay1 < 0)

		return delay1;



	delay2 = _spi_delay_to_ns(&spi->word_delay, xfer);

	if (delay2 < 0)

		return delay2;



	if (delay1 < delay2)

		memcpy(&xfer->word_delay, &spi->word_delay,

		       sizeof(xfer->word_delay));



	return 0;

}



static int __spi_validate(struct spi_device *spi, struct spi_message *message)

{

	struct spi_controller *ctlr = spi->controller;
@@ -3416,8 +3436,8 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message) 
				return -EINVAL;

		}



		if (xfer->word_delay_usecs < spi->word_delay_usecs)

			xfer->word_delay_usecs = spi->word_delay_usecs;

		if (_spi_xfer_word_delay_update(xfer, spi))

			return -EINVAL;

	}



	message->status = -EINPROGRESS;

include/linux/spi/spi.h

+2 −5
Original line number Diff line number Diff line
@@ -139,7 +139,7 @@ extern int spi_delay_exec(struct spi_delay *_delay, struct spi_transfer *xfer); 
 *	the spi_master.

 * @cs_gpiod: gpio descriptor of the chipselect line (optional, NULL when

 *	not using a GPIO line)

 * @word_delay_usecs: microsecond delay to be inserted between consecutive

 * @word_delay: delay to be inserted between consecutive

 *	words of a transfer

 *

 * @statistics: statistics for the spi_device
@@ -189,7 +189,7 @@ struct spi_device { 
	const char		*driver_override;

	int			cs_gpio;	/* LEGACY: chip select gpio */

	struct gpio_desc	*cs_gpiod;	/* chip select gpio desc */

	uint8_t			word_delay_usecs; /* inter-word delay */

	struct spi_delay	word_delay; /* inter-word delay */



	/* the statistics */

	struct spi_statistics	statistics;
@@ -781,8 +781,6 @@ extern void spi_res_release(struct spi_controller *ctlr, 
 * @delay_usecs: microseconds to delay after this transfer before

 *	(optionally) changing the chipselect status, then starting

 *	the next transfer or completing this @spi_message.

 * @word_delay_usecs: microseconds to inter word delay after each word size

 *	(set by bits_per_word) transmission.

 * @word_delay: inter word delay to be introduced after each word size

 *	(set by bits_per_word) transmission.

 * @effective_speed_hz: the effective SCK-speed that was used to
@@ -897,7 +895,6 @@ struct spi_transfer { 
#define	SPI_NBITS_DUAL		0x02 /* 2bits transfer */

#define	SPI_NBITS_QUAD		0x04 /* 4bits transfer */

	u8		bits_per_word;

	u8		word_delay_usecs;

	u16		delay_usecs;

	struct spi_delay	cs_change_delay;

	struct spi_delay	word_delay;

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