diff mbox series

[v7,2/7] spi: bitbang: Implement support for MOSI idle state configuration

Message ID de61a600b56ed9cb714d5ea87afa88948e70041e.1720810545.git.marcelo.schmitt@analog.com
State New
Headers show
Series Add support for AD4000 series of ADCs | expand

Commit Message

Marcelo Schmitt July 12, 2024, 7:21 p.m. UTC 
Some SPI peripherals may require strict MOSI line state when the controller
is not clocking out data. Implement support for MOSI idle state
configuration (low or high) by setting the data output line level on
controller setup and after transfers. Bitbang operations now call
controller specific set_mosi_idle() callback to set MOSI to its idle state.
The MOSI line is kept at its idle state if no tx buffer is provided.

Acked-by: Nuno Sa <nuno.sa@analog.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
---
 drivers/spi/spi-bitbang.c       | 24 ++++++++++++++++++++++++
 include/linux/spi/spi_bitbang.h |  1 +
 2 files changed, 25 insertions(+)
diff mbox series

Patch

diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c
index afb1b1105ec2..ebe18f0b5d23 100644
--- a/drivers/spi/spi-bitbang.c
+++ b/drivers/spi/spi-bitbang.c
@@ -54,21 +54,28 @@  static unsigned int bitbang_txrx_8(struct spi_device *spi,
 	struct spi_transfer	*t,
 	unsigned int flags)
 {
+	struct spi_bitbang	*bitbang;
 	unsigned int		bits = t->bits_per_word;
 	unsigned int		count = t->len;
 	const u8		*tx = t->tx_buf;
 	u8			*rx = t->rx_buf;
 
+	bitbang = spi_controller_get_devdata(spi->controller);
 	while (likely(count > 0)) {
 		u8		word = 0;
 
 		if (tx)
 			word = *tx++;
+		else
+			word = spi->mode & SPI_MOSI_IDLE_HIGH ? 0xFF : 0;
 		word = txrx_word(spi, ns, word, bits, flags);
 		if (rx)
 			*rx++ = word;
 		count -= 1;
 	}
+	if (bitbang->set_mosi_idle)
+		bitbang->set_mosi_idle(spi);
+
 	return t->len - count;
 }
 
@@ -78,21 +85,28 @@  static unsigned int bitbang_txrx_16(struct spi_device *spi,
 	struct spi_transfer	*t,
 	unsigned int flags)
 {
+	struct spi_bitbang	*bitbang;
 	unsigned int		bits = t->bits_per_word;
 	unsigned int		count = t->len;
 	const u16		*tx = t->tx_buf;
 	u16			*rx = t->rx_buf;
 
+	bitbang = spi_controller_get_devdata(spi->controller);
 	while (likely(count > 1)) {
 		u16		word = 0;
 
 		if (tx)
 			word = *tx++;
+		else
+			word = spi->mode & SPI_MOSI_IDLE_HIGH ? 0xFFFF : 0;
 		word = txrx_word(spi, ns, word, bits, flags);
 		if (rx)
 			*rx++ = word;
 		count -= 2;
 	}
+	if (bitbang->set_mosi_idle)
+		bitbang->set_mosi_idle(spi);
+
 	return t->len - count;
 }
 
@@ -102,21 +116,28 @@  static unsigned int bitbang_txrx_32(struct spi_device *spi,
 	struct spi_transfer	*t,
 	unsigned int flags)
 {
+	struct spi_bitbang	*bitbang;
 	unsigned int		bits = t->bits_per_word;
 	unsigned int		count = t->len;
 	const u32		*tx = t->tx_buf;
 	u32			*rx = t->rx_buf;
 
+	bitbang = spi_controller_get_devdata(spi->controller);
 	while (likely(count > 3)) {
 		u32		word = 0;
 
 		if (tx)
 			word = *tx++;
+		else
+			word = spi->mode & SPI_MOSI_IDLE_HIGH ? 0xFFFFFFFF : 0;
 		word = txrx_word(spi, ns, word, bits, flags);
 		if (rx)
 			*rx++ = word;
 		count -= 4;
 	}
+	if (bitbang->set_mosi_idle)
+		bitbang->set_mosi_idle(spi);
+
 	return t->len - count;
 }
 
@@ -192,6 +213,9 @@  int spi_bitbang_setup(struct spi_device *spi)
 			goto err_free;
 	}
 
+	if (bitbang->set_mosi_idle)
+		bitbang->set_mosi_idle(spi);
+
 	dev_dbg(&spi->dev, "%s, %u nsec/bit\n", __func__, 2 * cs->nsecs);
 
 	return 0;
diff --git a/include/linux/spi/spi_bitbang.h b/include/linux/spi/spi_bitbang.h
index 7ca08b430ed5..9bbbefef30dc 100644
--- a/include/linux/spi/spi_bitbang.h
+++ b/include/linux/spi/spi_bitbang.h
@@ -24,6 +24,7 @@  struct spi_bitbang {
 #define	BITBANG_CS_ACTIVE	1	/* normally nCS, active low */
 #define	BITBANG_CS_INACTIVE	0
 
+	void	(*set_mosi_idle)(struct spi_device *spi);
 	/* txrx_bufs() may handle dma mapping for transfers that don't
 	 * already have one (transfer.{tx,rx}_dma is zero), or use PIO
 	 */