From 22a6d41c871225bdd269a80fe04236071f429e2b Mon Sep 17 00:00:00 2001 From: Marcin Wojtas Date: Wed, 23 Dec 2020 12:38:27 +0200 Subject: [PATCH] spi: orion: enable support for switching CS every transferred byte Some SPI devices, require toggling the CS every transferred byte. Enable such possibility in the spi-orion driver. Note that in order to use it, in the driver of a secondary device attached to this controller, the SPI bus 'mode' field must be updated with SPI_CS_WORD flag before calling spi_setup() routine. In addition to that include a work-around - some devices, such as certain models of SLIC (Subscriber Line Interface Card), may require extra delay after CS toggling, so add a minimal timing relaxation in relevant places. Signed-off-by: Marcin Wojtas Signed-off-by: Konstantin Porotchkin Link: https://lore.kernel.org/r/20201223103827.29721-3-kostap@marvell.com Signed-off-by: Mark Brown --- drivers/spi/spi-orion.c | 32 ++++++++++++++++++++++++++++---- 1 file changed, 28 insertions(+), 4 deletions(-) diff --git a/drivers/spi/spi-orion.c b/drivers/spi/spi-orion.c index 133727552e99..68ed7fd64256 100644 --- a/drivers/spi/spi-orion.c +++ b/drivers/spi/spi-orion.c @@ -375,8 +375,15 @@ orion_spi_write_read_8bit(struct spi_device *spi, { void __iomem *tx_reg, *rx_reg, *int_reg; struct orion_spi *orion_spi; + bool cs_single_byte; + + cs_single_byte = spi->mode & SPI_CS_WORD; orion_spi = spi_master_get_devdata(spi->master); + + if (cs_single_byte) + orion_spi_set_cs(spi, 0); + tx_reg = spi_reg(orion_spi, ORION_SPI_DATA_OUT_REG); rx_reg = spi_reg(orion_spi, ORION_SPI_DATA_IN_REG); int_reg = spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG); @@ -390,6 +397,11 @@ orion_spi_write_read_8bit(struct spi_device *spi, writel(0, tx_reg); if (orion_spi_wait_till_ready(orion_spi) < 0) { + if (cs_single_byte) { + orion_spi_set_cs(spi, 1); + /* Satisfy some SLIC devices requirements */ + udelay(4); + } dev_err(&spi->dev, "TXS timed out\n"); return -1; } @@ -397,6 +409,12 @@ orion_spi_write_read_8bit(struct spi_device *spi, if (rx_buf && *rx_buf) *(*rx_buf)++ = readl(rx_reg); + if (cs_single_byte) { + orion_spi_set_cs(spi, 1); + /* Satisfy some SLIC devices requirements */ + udelay(4); + } + return 1; } @@ -407,6 +425,11 @@ orion_spi_write_read_16bit(struct spi_device *spi, void __iomem *tx_reg, *rx_reg, *int_reg; struct orion_spi *orion_spi; + if (spi->mode & SPI_CS_WORD) { + dev_err(&spi->dev, "SPI_CS_WORD is only supported for 8 bit words\n"); + return -1; + } + orion_spi = spi_master_get_devdata(spi->master); tx_reg = spi_reg(orion_spi, ORION_SPI_DATA_OUT_REG); rx_reg = spi_reg(orion_spi, ORION_SPI_DATA_IN_REG); @@ -446,12 +469,13 @@ orion_spi_write_read(struct spi_device *spi, struct spi_transfer *xfer) orion_spi = spi_master_get_devdata(spi->master); /* - * Use SPI direct write mode if base address is available. Otherwise - * fall back to PIO mode for this transfer. + * Use SPI direct write mode if base address is available + * and SPI_CS_WORD flag is not set. + * Otherwise fall back to PIO mode for this transfer. */ vaddr = orion_spi->child[cs].direct_access.vaddr; - if (vaddr && xfer->tx_buf && word_len == 8) { + if (vaddr && xfer->tx_buf && word_len == 8 && (spi->mode & SPI_CS_WORD) == 0) { unsigned int cnt = count / 4; unsigned int rem = count % 4; @@ -636,7 +660,7 @@ static int orion_spi_probe(struct platform_device *pdev) } /* we support all 4 SPI modes and LSB first option */ - master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_LSB_FIRST; + master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_LSB_FIRST | SPI_CS_WORD; master->set_cs = orion_spi_set_cs; master->transfer_one = orion_spi_transfer_one; master->num_chipselect = ORION_NUM_CHIPSELECTS;