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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 <mw@semihalf.com>
Signed-off-by: Konstantin Porotchkin <kostap@marvell.com>
Link: https://lore.kernel.org/r/20201223103827.29721-3-kostap@marvell.com
Signed-off-by: Mark Brown <broonie@kernel.org>
master
Marcin Wojtas 2020-12-23 12:38:27 +02:00 committed by Mark Brown
parent e2be70318d
commit 22a6d41c87
No known key found for this signature in database
GPG Key ID: 24D68B725D5487D0
1 changed files with 28 additions and 4 deletions
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32
drivers/spi/spi-orion.c
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@ -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;