diff mbox series

[v6,2/7] spi: bitbang: Implement support for MOSI idle state configuration

Message ID b08e21823638c241228f4bc27a7bf5d4ed88d54a.1719686465.git.marcelo.schmitt@analog.com (mailing list archive)
State New
Headers show
Series Add support for AD4000 series of ADCs | expand

Commit Message

Marcelo Schmitt June 29, 2024, 7:05 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() call back
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>
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(+)

Comments

Jonathan Cameron June 30, 2024, 10:52 a.m. UTC | #1 
On Sat, 29 Jun 2024 16:05:05 -0300
Marcelo Schmitt <marcelo.schmitt@analog.com> wrote:

> 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() call back
> to set MOSI to its idle state.
> The MOSI line is kept at its idle state if no tx buffer is provided.

Slightly odd wrapping - this doesn't warrant 3 paragraphs, so I'd just
reflow it into one. 

I'm not a fan of counting F's, so would have gone with GENMASK for those
but it's not the local style, so fair enough to hard code them.
FWIW given it's been a long time since I messed around in SPI controller
drivers...

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>


> 
> Acked-by: Nuno Sa <nuno.sa@analog.com>
> Reviewed-by: David Lechner <dlechner@baylibre.com>
> Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
diff mbox series

Patch

diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c
index ca5cc67555c5..8cc522bf444c 100644
--- a/drivers/spi/spi-bitbang.c
+++ b/drivers/spi/spi-bitbang.c
@@ -63,21 +63,28 @@  static unsigned bitbang_txrx_8(
 	unsigned flags
 )
 {
+	struct spi_bitbang	*bitbang;
 	unsigned		bits = t->bits_per_word;
 	unsigned		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;
 }
 
@@ -92,21 +99,28 @@  static unsigned bitbang_txrx_16(
 	unsigned flags
 )
 {
+	struct spi_bitbang	*bitbang;
 	unsigned		bits = t->bits_per_word;
 	unsigned		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;
 }
 
@@ -121,21 +135,28 @@  static unsigned bitbang_txrx_32(
 	unsigned flags
 )
 {
+	struct spi_bitbang	*bitbang;
 	unsigned		bits = t->bits_per_word;
 	unsigned		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;
 }
 
@@ -211,6 +232,9 @@  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 b930eca2ef7b..1a54b593c691 100644
--- a/include/linux/spi/spi_bitbang.h
+++ b/include/linux/spi/spi_bitbang.h
@@ -22,6 +22,7 @@  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
 	 */