[PATCH 2/2] spi: bitbang: switch to the generic implementation of transfer_one_message

[PATCH 2/2] spi: bitbang: switch to the generic implementation of transfer_one_message

[Heiner Kallweit]

Change the bitbang driver to use the generic implementation of
transfer_one_message. This simplifies the bitbang driver code and
provides benefits like the statistics in the generic implementation.

Successfully tested on a IMX6-based system (spi-imx) and on a MIPS-based
router (OpenWRT with spi-ath79).

Signed-off-by: Heiner Kallweit <hkallweit1-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 drivers/spi/spi-bitbang.c | 125 +++++++++++++---------------------------------
 1 file changed, 36 insertions(+), 89 deletions(-)

diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c
index ad3168d..7f5ffbf 100644
--- a/drivers/spi/spi-bitbang.c
+++ b/drivers/spi/spi-bitbang.c
@@ -24,6 +24,8 @@
 #include <linux/spi/spi.h>
 #include <linux/spi/spi_bitbang.h>
 
+#define SPI_BITBANG_CS_DELAY	100
+
 
 /*----------------------------------------------------------------------*/
 
@@ -265,100 +267,28 @@ static int spi_bitbang_prepare_hardware(struct spi_master *spi)
 }
 
 static int spi_bitbang_transfer_one(struct spi_master *master,
-				    struct spi_message *m)
+				    struct spi_device *spi,
+				    struct spi_transfer *transfer)
 {
-	struct spi_bitbang	*bitbang;
-	unsigned		nsecs;
-	struct spi_transfer	*t = NULL;
-	unsigned		cs_change;
-	int			status;
-	struct spi_device	*spi = m->spi;
-
-	bitbang = spi_master_get_devdata(master);
-
-	/* FIXME this is made-up ... the correct value is known to
-	 * word-at-a-time bitbang code, and presumably chipselect()
-	 * should enforce these requirements too?
-	 */
-	nsecs = 100;
-
-	cs_change = 1;
-	status = 0;
-
-	list_for_each_entry(t, &m->transfers, transfer_list) {
-
-		if (bitbang->setup_transfer) {
-			status = bitbang->setup_transfer(spi, t);
-			if (status < 0)
-				break;
-		}
-
-		/* set up default clock polarity, and activate chip;
-		 * this implicitly updates clock and spi modes as
-		 * previously recorded for this device via setup().
-		 * (and also deselects any other chip that might be
-		 * selected ...)
-		 */
-		if (cs_change) {
-			bitbang->chipselect(spi, BITBANG_CS_ACTIVE);
-			ndelay(nsecs);
-		}
-		cs_change = t->cs_change;
-		if (!t->tx_buf && !t->rx_buf && t->len) {
-			status = -EINVAL;
-			break;
-		}
-
-		/* transfer data.  the lower level code handles any
-		 * new dma mappings it needs. our caller always gave
-		 * us dma-safe buffers.
-		 */
-		if (t->len) {
-			/* REVISIT dma API still needs a designated
-			 * DMA_ADDR_INVALID; ~0 might be better.
-			 */
-			if (!m->is_dma_mapped)
-				t->rx_dma = t->tx_dma = 0;
-			status = bitbang->txrx_bufs(spi, t);
-		}
-		if (status > 0)
-			m->actual_length += status;
-		if (status != t->len) {
-			/* always report some kind of error */
-			if (status >= 0)
-				status = -EREMOTEIO;
-			break;
-		}
-		status = 0;
+	struct spi_bitbang *bitbang = spi_master_get_devdata(master);
+	int status = 0;
 
-		/* protocol tweaks before next transfer */
-		if (t->delay_usecs)
-			udelay(t->delay_usecs);
-
-		if (cs_change &&
-		    !list_is_last(&t->transfer_list, &m->transfers)) {
-			/* sometimes a short mid-message deselect of the chip
-			 * may be needed to terminate a mode or command
-			 */
-			ndelay(nsecs);
-			bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
-			ndelay(nsecs);
-		}
+	if (bitbang->setup_transfer) {
+		status = bitbang->setup_transfer(spi, transfer);
+		if (status < 0)
+			goto out;
 	}
 
-	m->status = status;
+	if (transfer->len)
+		status = bitbang->txrx_bufs(spi, transfer);
 
-	/* normally deactivate chipselect ... unless no error and
-	 * cs_change has hinted that the next message will probably
-	 * be for this chip too.
-	 */
-	if (!(status == 0 && cs_change)) {
-		ndelay(nsecs);
-		bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
-		ndelay(nsecs);
-	}
+	if (status == transfer->len)
+		status = 0;
+	else if (status >= 0)
+		status = -EREMOTEIO;
 
-	spi_finalize_current_message(master);
+out:
+	spi_finalize_current_transfer(master);
 
 	return status;
 }
@@ -376,6 +306,22 @@ static int spi_bitbang_unprepare_hardware(struct spi_master *spi)
 	return 0;
 }
 
+static void spi_bitbang_set_cs(struct spi_device *spi, bool enable)
+{
+	struct spi_bitbang *bitbang = spi_master_get_devdata(spi->master);
+
+	/* SPI core provides CS high / low, but bitbang driver
+	 * expects CS active
+	 * spi device driver takes care of handling SPI_CS_HIGH
+	 */
+	enable = (!!(spi->mode & SPI_CS_HIGH) == enable);
+
+	ndelay(SPI_BITBANG_CS_DELAY);
+	bitbang->chipselect(spi, enable ? BITBANG_CS_ACTIVE :
+			    BITBANG_CS_INACTIVE);
+	ndelay(SPI_BITBANG_CS_DELAY);
+}
+
 /*----------------------------------------------------------------------*/
 
 /**
@@ -424,7 +370,8 @@ int spi_bitbang_start(struct spi_bitbang *bitbang)
 
 	master->prepare_transfer_hardware = spi_bitbang_prepare_hardware;
 	master->unprepare_transfer_hardware = spi_bitbang_unprepare_hardware;
-	master->transfer_one_message = spi_bitbang_transfer_one;
+	master->transfer_one = spi_bitbang_transfer_one;
+	master->set_cs = spi_bitbang_set_cs;
 
 	if (!bitbang->txrx_bufs) {
 		bitbang->use_dma = 0;
-- 
2.5.3

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Re: [PATCH 2/2] spi: bitbang: switch to the generic implementation of transfer_one_message

[Mark Brown]

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On Tue, Sep 29, 2015 at 11:15:53PM +0200, Heiner Kallweit wrote:
> Change the bitbang driver to use the generic implementation of
> transfer_one_message. This simplifies the bitbang driver code and
> provides benefits like the statistics in the generic implementation.

I'm missing patch 1 and/or a cover letter here - what is it and what are
the dependencies?

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Re: [PATCH 2/2] spi: bitbang: switch to the generic implementation of transfer_one_message

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 385 bytes --]

On Tue, Sep 29, 2015 at 11:15:53PM +0200, Heiner Kallweit wrote:
> Change the bitbang driver to use the generic implementation of
> transfer_one_message. This simplifies the bitbang driver code and
> provides benefits like the statistics in the generic implementation.

Sorry, I actually have patch 1 but they weren't threaded together so got
separated by some other mail in my inbox.

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Applied "spi: bitbang: switch to the generic implementation of transfer_one_message" to the spi tree

[Mark Brown]

The patch

   spi: bitbang: switch to the generic implementation of transfer_one_message

has been applied to the spi tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From 0037686596832572bbca05ab168d9884d7d704c1 Mon Sep 17 00:00:00 2001
From: Heiner Kallweit <hkallweit1-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Date: Tue, 29 Sep 2015 23:15:53 +0200
Subject: [PATCH] spi: bitbang: switch to the generic implementation of
 transfer_one_message

Change the bitbang driver to use the generic implementation of
transfer_one_message. This simplifies the bitbang driver code and
provides benefits like the statistics in the generic implementation.

Successfully tested on a IMX6-based system (spi-imx) and on a MIPS-based
router (OpenWRT with spi-ath79).

Signed-off-by: Heiner Kallweit <hkallweit1-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Signed-off-by: Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
 drivers/spi/spi-bitbang.c | 125 +++++++++++++---------------------------------
 1 file changed, 36 insertions(+), 89 deletions(-)

diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c
index ad3168d..3aa9e6e 100644
--- a/drivers/spi/spi-bitbang.c
+++ b/drivers/spi/spi-bitbang.c
@@ -24,6 +24,8 @@
 #include <linux/spi/spi.h>
 #include <linux/spi/spi_bitbang.h>
 
+#define SPI_BITBANG_CS_DELAY	100
+
 
 /*----------------------------------------------------------------------*/
 
@@ -265,100 +267,28 @@ static int spi_bitbang_prepare_hardware(struct spi_master *spi)
 }
 
 static int spi_bitbang_transfer_one(struct spi_master *master,
-				    struct spi_message *m)
+				    struct spi_device *spi,
+				    struct spi_transfer *transfer)
 {
-	struct spi_bitbang	*bitbang;
-	unsigned		nsecs;
-	struct spi_transfer	*t = NULL;
-	unsigned		cs_change;
-	int			status;
-	struct spi_device	*spi = m->spi;
-
-	bitbang = spi_master_get_devdata(master);
-
-	/* FIXME this is made-up ... the correct value is known to
-	 * word-at-a-time bitbang code, and presumably chipselect()
-	 * should enforce these requirements too?
-	 */
-	nsecs = 100;
-
-	cs_change = 1;
-	status = 0;
-
-	list_for_each_entry(t, &m->transfers, transfer_list) {
-
-		if (bitbang->setup_transfer) {
-			status = bitbang->setup_transfer(spi, t);
-			if (status < 0)
-				break;
-		}
-
-		/* set up default clock polarity, and activate chip;
-		 * this implicitly updates clock and spi modes as
-		 * previously recorded for this device via setup().
-		 * (and also deselects any other chip that might be
-		 * selected ...)
-		 */
-		if (cs_change) {
-			bitbang->chipselect(spi, BITBANG_CS_ACTIVE);
-			ndelay(nsecs);
-		}
-		cs_change = t->cs_change;
-		if (!t->tx_buf && !t->rx_buf && t->len) {
-			status = -EINVAL;
-			break;
-		}
-
-		/* transfer data.  the lower level code handles any
-		 * new dma mappings it needs. our caller always gave
-		 * us dma-safe buffers.
-		 */
-		if (t->len) {
-			/* REVISIT dma API still needs a designated
-			 * DMA_ADDR_INVALID; ~0 might be better.
-			 */
-			if (!m->is_dma_mapped)
-				t->rx_dma = t->tx_dma = 0;
-			status = bitbang->txrx_bufs(spi, t);
-		}
-		if (status > 0)
-			m->actual_length += status;
-		if (status != t->len) {
-			/* always report some kind of error */
-			if (status >= 0)
-				status = -EREMOTEIO;
-			break;
-		}
-		status = 0;
+	struct spi_bitbang *bitbang = spi_master_get_devdata(master);
+	int status = 0;
 
-		/* protocol tweaks before next transfer */
-		if (t->delay_usecs)
-			udelay(t->delay_usecs);
-
-		if (cs_change &&
-		    !list_is_last(&t->transfer_list, &m->transfers)) {
-			/* sometimes a short mid-message deselect of the chip
-			 * may be needed to terminate a mode or command
-			 */
-			ndelay(nsecs);
-			bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
-			ndelay(nsecs);
-		}
+	if (bitbang->setup_transfer) {
+		status = bitbang->setup_transfer(spi, transfer);
+		if (status < 0)
+			goto out;
 	}
 
-	m->status = status;
+	if (transfer->len)
+		status = bitbang->txrx_bufs(spi, transfer);
 
-	/* normally deactivate chipselect ... unless no error and
-	 * cs_change has hinted that the next message will probably
-	 * be for this chip too.
-	 */
-	if (!(status == 0 && cs_change)) {
-		ndelay(nsecs);
-		bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
-		ndelay(nsecs);
-	}
+	if (status == transfer->len)
+		status = 0;
+	else if (status >= 0)
+		status = -EREMOTEIO;
 
-	spi_finalize_current_message(master);
+out:
+	spi_finalize_current_transfer(master);
 
 	return status;
 }
@@ -376,6 +306,22 @@ static int spi_bitbang_unprepare_hardware(struct spi_master *spi)
 	return 0;
 }
 
+static void spi_bitbang_set_cs(struct spi_device *spi, bool enable)
+{
+	struct spi_bitbang *bitbang = spi_master_get_devdata(spi->master);
+
+	/* SPI core provides CS high / low, but bitbang driver
+	 * expects CS active
+	 * spi device driver takes care of handling SPI_CS_HIGH
+	 */
+	enable = (!!(spi->mode & SPI_CS_HIGH) == enable);
+
+	ndelay(SPI_BITBANG_CS_DELAY);
+	bitbang->chipselect(spi, enable ? BITBANG_CS_ACTIVE :
+			    BITBANG_CS_INACTIVE);
+	ndelay(SPI_BITBANG_CS_DELAY);
+}
+
 /*----------------------------------------------------------------------*/
 
 /**
@@ -424,7 +370,8 @@ int spi_bitbang_start(struct spi_bitbang *bitbang)
 
 	master->prepare_transfer_hardware = spi_bitbang_prepare_hardware;
 	master->unprepare_transfer_hardware = spi_bitbang_unprepare_hardware;
-	master->transfer_one_message = spi_bitbang_transfer_one;
+	master->transfer_one = spi_bitbang_transfer_one;
+	master->set_cs = spi_bitbang_set_cs;
 
 	if (!bitbang->txrx_bufs) {
 		bitbang->use_dma = 0;
-- 
2.5.0

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