Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit aca75157 authored by Heiner Kallweit's avatar Heiner Kallweit Committed by Mark Brown
Browse files

spi: fsl-espi: add support for ESPI RXSKIP mode 



This patch adds support for ESPI RXSKIP mode. This mode is optimized
for flash reads:
- sends a number of bytes and then reads a number of bytes
- shifts out zeros automatically when reading

Supporting RXSKIP mode is a prerequisite for supporting dual output
read mode.

Signed-off-by: default avatarHeiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 8f3086d2

drivers/spi/spi-fsl-espi.c

+47 −4
Original line number Diff line number Diff line
@@ -150,7 +150,8 @@ static void fsl_espi_copy_to_buf(struct spi_message *m, 
	list_for_each_entry(t, &m->transfers, transfer_list) {

		if (t->tx_buf)

			fsl_espi_memcpy_swab(buf, t->tx_buf, m, t);

		else

		/* In RXSKIP mode controller shifts out zeros internally */

		else if (!mspi->rxskip)

			memset(buf, 0, t->len);

		buf += t->len;

	}
@@ -203,6 +204,37 @@ static int fsl_espi_check_message(struct spi_message *m) 
	return 0;

}



static unsigned int fsl_espi_check_rxskip_mode(struct spi_message *m)

{

	struct spi_transfer *t;

	unsigned int i = 0, rxskip = 0;



	/*

	 * prerequisites for ESPI rxskip mode:

	 * - message has two transfers

	 * - first transfer is a write and second is a read

	 *

	 * In addition the current low-level transfer mechanism requires

	 * that the rxskip bytes fit into the TX FIFO. Else the transfer

	 * would hang because after the first FSL_ESPI_FIFO_SIZE bytes

	 * the TX FIFO isn't re-filled.

	 */

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

		if (i == 0) {

			if (!t->tx_buf || t->rx_buf ||

			    t->len > FSL_ESPI_FIFO_SIZE)

				return 0;

			rxskip = t->len;

		} else if (i == 1) {

			if (t->tx_buf || !t->rx_buf)

				return 0;

		}

		i++;

	}



	return i == 2 ? rxskip : 0;

}



static void fsl_espi_fill_tx_fifo(struct mpc8xxx_spi *mspi, u32 events)

{

	u32 tx_fifo_avail;
@@ -281,7 +313,7 @@ static void fsl_espi_setup_transfer(struct spi_device *spi, 
static int fsl_espi_bufs(struct spi_device *spi, struct spi_transfer *t)

{

	struct mpc8xxx_spi *mpc8xxx_spi = spi_master_get_devdata(spi->master);

	u32 mask;

	u32 mask, spcom;

	int ret;



	mpc8xxx_spi->rx_len = t->len;
@@ -293,8 +325,18 @@ static int fsl_espi_bufs(struct spi_device *spi, struct spi_transfer *t) 
	reinit_completion(&mpc8xxx_spi->done);



	/* Set SPCOM[CS] and SPCOM[TRANLEN] field */

	fsl_espi_write_reg(mpc8xxx_spi, ESPI_SPCOM,

		(SPCOM_CS(spi->chip_select) | SPCOM_TRANLEN(t->len - 1)));

	spcom = SPCOM_CS(spi->chip_select);

	spcom |= SPCOM_TRANLEN(t->len - 1);



	/* configure RXSKIP mode */

	if (mpc8xxx_spi->rxskip) {

		spcom |= SPCOM_RXSKIP(mpc8xxx_spi->rxskip);

		mpc8xxx_spi->tx_len = mpc8xxx_spi->rxskip;

		mpc8xxx_spi->rx_len = t->len - mpc8xxx_spi->rxskip;

		mpc8xxx_spi->rx = t->rx_buf + mpc8xxx_spi->rxskip;

	}



	fsl_espi_write_reg(mpc8xxx_spi, ESPI_SPCOM, spcom);



	/* enable interrupts */

	mask = SPIM_DON;
@@ -326,6 +368,7 @@ static int fsl_espi_trans(struct spi_message *m, struct spi_transfer *trans) 
	struct spi_device *spi = m->spi;

	int ret;



	mspi->rxskip = fsl_espi_check_rxskip_mode(m);

	fsl_espi_copy_to_buf(m, mspi);

	fsl_espi_setup_transfer(spi, trans);

drivers/spi/spi-fsl-lib.h

+1 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ struct mpc8xxx_spi { 
#if IS_ENABLED(CONFIG_SPI_FSL_ESPI)

	unsigned int rx_len;

	unsigned int tx_len;

	unsigned int rxskip;

	u8 *local_buf;

	spinlock_t lock;

#endif