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Commit 00376865 authored by Heiner Kallweit's avatar Heiner Kallweit Committed by Mark Brown
Browse files

spi: bitbang: switch to the generic implementation of transfer_one_message 



Change the bitbang driver to use the generic implementation of
transfer_one_message. This simplifies the bitbang driver code and
provides benefits like the statistics in the generic implementation.

Successfully tested on a IMX6-based system (spi-imx) and on a MIPS-based
router (OpenWRT with spi-ath79).

Signed-off-by: default avatarHeiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent e30d8f23

drivers/spi/spi-bitbang.c

+36 −89
Original line number Diff line number Diff line
@@ -24,6 +24,8 @@ 
#include <linux/spi/spi.h>

#include <linux/spi/spi_bitbang.h>



#define SPI_BITBANG_CS_DELAY	100





/*----------------------------------------------------------------------*/
@@ -265,100 +267,28 @@ static int spi_bitbang_prepare_hardware(struct spi_master *spi) 
}



static int spi_bitbang_transfer_one(struct spi_master *master,

				    struct spi_message *m)

				    struct spi_device *spi,

				    struct spi_transfer *transfer)

{

	struct spi_bitbang	*bitbang;

	unsigned		nsecs;

	struct spi_transfer	*t = NULL;

	unsigned		cs_change;

	int			status;

	struct spi_device	*spi = m->spi;



	bitbang = spi_master_get_devdata(master);



	/* FIXME this is made-up ... the correct value is known to

	 * word-at-a-time bitbang code, and presumably chipselect()

	 * should enforce these requirements too?

	 */

	nsecs = 100;



	cs_change = 1;

	status = 0;



	list_for_each_entry(t, &m->transfers, transfer_list) {

	struct spi_bitbang *bitbang = spi_master_get_devdata(master);

	int status = 0;



	if (bitbang->setup_transfer) {

			status = bitbang->setup_transfer(spi, t);

		status = bitbang->setup_transfer(spi, transfer);

		if (status < 0)

				break;

			goto out;

	}



		/* set up default clock polarity, and activate chip;

		 * this implicitly updates clock and spi modes as

		 * previously recorded for this device via setup().

		 * (and also deselects any other chip that might be

		 * selected ...)

		 */

		if (cs_change) {

			bitbang->chipselect(spi, BITBANG_CS_ACTIVE);

			ndelay(nsecs);

		}

		cs_change = t->cs_change;

		if (!t->tx_buf && !t->rx_buf && t->len) {

			status = -EINVAL;

			break;

		}

	if (transfer->len)

		status = bitbang->txrx_bufs(spi, transfer);



		/* transfer data.  the lower level code handles any

		 * new dma mappings it needs. our caller always gave

		 * us dma-safe buffers.

		 */

		if (t->len) {

			/* REVISIT dma API still needs a designated

			 * DMA_ADDR_INVALID; ~0 might be better.

			 */

			if (!m->is_dma_mapped)

				t->rx_dma = t->tx_dma = 0;

			status = bitbang->txrx_bufs(spi, t);

		}

		if (status > 0)

			m->actual_length += status;

		if (status != t->len) {

			/* always report some kind of error */

			if (status >= 0)

				status = -EREMOTEIO;

			break;

		}

	if (status == transfer->len)

		status = 0;

	else if (status >= 0)

		status = -EREMOTEIO;



		/* protocol tweaks before next transfer */

		if (t->delay_usecs)

			udelay(t->delay_usecs);



		if (cs_change &&

		    !list_is_last(&t->transfer_list, &m->transfers)) {

			/* sometimes a short mid-message deselect of the chip

			 * may be needed to terminate a mode or command

			 */

			ndelay(nsecs);

			bitbang->chipselect(spi, BITBANG_CS_INACTIVE);

			ndelay(nsecs);

		}

	}



	m->status = status;



	/* normally deactivate chipselect ... unless no error and

	 * cs_change has hinted that the next message will probably

	 * be for this chip too.

	 */

	if (!(status == 0 && cs_change)) {

		ndelay(nsecs);

		bitbang->chipselect(spi, BITBANG_CS_INACTIVE);

		ndelay(nsecs);

	}



	spi_finalize_current_message(master);

out:

	spi_finalize_current_transfer(master);



	return status;

}
@@ -376,6 +306,22 @@ static int spi_bitbang_unprepare_hardware(struct spi_master *spi) 
	return 0;

}



static void spi_bitbang_set_cs(struct spi_device *spi, bool enable)

{

	struct spi_bitbang *bitbang = spi_master_get_devdata(spi->master);



	/* SPI core provides CS high / low, but bitbang driver

	 * expects CS active

	 * spi device driver takes care of handling SPI_CS_HIGH

	 */

	enable = (!!(spi->mode & SPI_CS_HIGH) == enable);



	ndelay(SPI_BITBANG_CS_DELAY);

	bitbang->chipselect(spi, enable ? BITBANG_CS_ACTIVE :

			    BITBANG_CS_INACTIVE);

	ndelay(SPI_BITBANG_CS_DELAY);

}



/*----------------------------------------------------------------------*/



/**
@@ -424,7 +370,8 @@ int spi_bitbang_start(struct spi_bitbang *bitbang) 


	master->prepare_transfer_hardware = spi_bitbang_prepare_hardware;

	master->unprepare_transfer_hardware = spi_bitbang_unprepare_hardware;

	master->transfer_one_message = spi_bitbang_transfer_one;

	master->transfer_one = spi_bitbang_transfer_one;

	master->set_cs = spi_bitbang_set_cs;



	if (!bitbang->txrx_bufs) {

		bitbang->use_dma = 0;