[PATCH v6 0/5] spi: dw: DW SPI DMA Driver updates

[PATCH v6 0/5] spi: dw: DW SPI DMA Driver updates

[Joy Chakraborty]

This Patch series adds support for 32 bits per word trasfers using DMA
and some defensive checks around dma controller capabilities.
---
V1 Changes : Add support for AxSize=4 bytes to support 32bits/word.
---
V1->V2 Changes : Add dma capability check to make sure address widths
are supported.
---
V2->V3 Changes : Split changes , add DMA direction check and other
cosmetic chnages.
---
V3->V4 Changes : Fix Sparce Warning
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202303270715.w9sMJhIh-lkp@intel.com/
---
V4->V5 Changes : Preserve reverse xmas Tree order, move direction
check before initalisation of further capabilities, remove zero
initialisations, remove error OR'ing.
---
V5->V6 Changes :
	-Remove case of n_bytes=3 using 4_bytes buswidth
	-Avoid forward decaration
	-Break capability check patch into 2
	-round n_bytes to power of 2 ( Bug Fix)
	-Add more explanation in commit text.
---

Joy Chakraborty (5):
  spi: dw: Add 32 bpw support to SPI DW DMA driver
  spi: dw: Move "dw_spi_can_dma" function
  spi: dw: Add DMA directional capability check
  spi: dw: Add DMA address widths capability check
  spi: dw: Round of n_bytes to power of 2

 drivers/spi/spi-dw-core.c |  2 +-
 drivers/spi/spi-dw-dma.c  | 75 +++++++++++++++++++++++++++++----------
 drivers/spi/spi-dw.h      |  1 +
 3 files changed, 59 insertions(+), 19 deletions(-)

-- 
2.40.0.634.g4ca3ef3211-goog

[PATCH v6 1/5] spi: dw: Add 32 bpw support to SPI DW DMA driver

[Joy Chakraborty]

Add Support for AxSize = 4 bytes configuration from dw dma driver if
n_bytes i.e. number of bytes per write to fifo is 4.

Number of bytes written to fifo per write is depended on the bits/word
configuration being used which the DW core driver translates to n_bytes.
Hence, for bits per word values between 17 and 32 n_bytes should be
equal to 4.

Signed-off-by: Joy Chakraborty <joychakr@google.com>
---
 drivers/spi/spi-dw-dma.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-dw-dma.c b/drivers/spi/spi-dw-dma.c
index ababb910b391..c1b42cb59965 100644
--- a/drivers/spi/spi-dw-dma.c
+++ b/drivers/spi/spi-dw-dma.c
@@ -208,12 +208,16 @@ static bool dw_spi_can_dma(struct spi_controller *master,
 
 static enum dma_slave_buswidth dw_spi_dma_convert_width(u8 n_bytes)
 {
-	if (n_bytes == 1)
+	switch (n_bytes) {
+	case 1:
 		return DMA_SLAVE_BUSWIDTH_1_BYTE;
-	else if (n_bytes == 2)
+	case 2:
 		return DMA_SLAVE_BUSWIDTH_2_BYTES;
-
-	return DMA_SLAVE_BUSWIDTH_UNDEFINED;
+	case 4:
+		return DMA_SLAVE_BUSWIDTH_4_BYTES;
+	default:
+		return DMA_SLAVE_BUSWIDTH_UNDEFINED;
+	}
 }
 
 static int dw_spi_dma_wait(struct dw_spi *dws, unsigned int len, u32 speed)
-- 
2.40.0.634.g4ca3ef3211-goog

[PATCH v6 2/5] spi: dw: Move "dw_spi_can_dma" function

[Joy Chakraborty]

Move "dw_spi_can_dma" function implementation below
"dw_spi_dma_convert_width" function for handing compile dependency in
future patches.

Signed-off-by: Joy Chakraborty <joychakr@google.com>
---
 drivers/spi/spi-dw-dma.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/spi/spi-dw-dma.c b/drivers/spi/spi-dw-dma.c
index c1b42cb59965..75e1b11af7c9 100644
--- a/drivers/spi/spi-dw-dma.c
+++ b/drivers/spi/spi-dw-dma.c
@@ -198,14 +198,6 @@ static irqreturn_t dw_spi_dma_transfer_handler(struct dw_spi *dws)
 	return IRQ_HANDLED;
 }
 
-static bool dw_spi_can_dma(struct spi_controller *master,
-			   struct spi_device *spi, struct spi_transfer *xfer)
-{
-	struct dw_spi *dws = spi_controller_get_devdata(master);
-
-	return xfer->len > dws->fifo_len;
-}
-
 static enum dma_slave_buswidth dw_spi_dma_convert_width(u8 n_bytes)
 {
 	switch (n_bytes) {
@@ -220,6 +212,15 @@ static enum dma_slave_buswidth dw_spi_dma_convert_width(u8 n_bytes)
 	}
 }
 
+static bool dw_spi_can_dma(struct spi_controller *master,
+			   struct spi_device *spi, struct spi_transfer *xfer)
+{
+	struct dw_spi *dws = spi_controller_get_devdata(master);
+
+	return xfer->len > dws->fifo_len;
+}
+
+
 static int dw_spi_dma_wait(struct dw_spi *dws, unsigned int len, u32 speed)
 {
 	unsigned long long ms;
-- 
2.40.0.634.g4ca3ef3211-goog

[PATCH v6 3/5] spi: dw: Add DMA directional capability check

[Joy Chakraborty]

Check capabilities of DMA controller during init to make sure it is
capable of handling MEM2DEV for tx channel, DEV2MEM for rx channel.

Current DW DMA driver requires both tx and rx channel to be configured
and functional for any kind of transfers to take effect including
half duplex. Hence, check for both tx and rx direction and fail on
unavailbility of either.

Signed-off-by: Joy Chakraborty <joychakr@google.com>
---
 drivers/spi/spi-dw-dma.c | 39 ++++++++++++++++++++++++++++++---------
 1 file changed, 30 insertions(+), 9 deletions(-)

diff --git a/drivers/spi/spi-dw-dma.c b/drivers/spi/spi-dw-dma.c
index 75e1b11af7c9..e1dd13fe4fd0 100644
--- a/drivers/spi/spi-dw-dma.c
+++ b/drivers/spi/spi-dw-dma.c
@@ -72,12 +72,22 @@ static void dw_spi_dma_maxburst_init(struct dw_spi *dws)
 	dw_writel(dws, DW_SPI_DMATDLR, dws->txburst);
 }
 
-static void dw_spi_dma_sg_burst_init(struct dw_spi *dws)
+static int dw_spi_dma_caps_init(struct dw_spi *dws)
 {
-	struct dma_slave_caps tx = {0}, rx = {0};
+	struct dma_slave_caps tx, rx;
+	int ret;
+
+	ret = dma_get_slave_caps(dws->txchan, &tx);
+	if (ret)
+		return ret;
+
+	ret = dma_get_slave_caps(dws->rxchan, &rx);
+	if (ret)
+		return ret;
 
-	dma_get_slave_caps(dws->txchan, &tx);
-	dma_get_slave_caps(dws->rxchan, &rx);
+	if (!(tx.directions & BIT(DMA_MEM_TO_DEV) &&
+	      rx.directions & BIT(DMA_DEV_TO_MEM)))
+		return -ENXIO;
 
 	if (tx.max_sg_burst > 0 && rx.max_sg_burst > 0)
 		dws->dma_sg_burst = min(tx.max_sg_burst, rx.max_sg_burst);
@@ -95,6 +105,7 @@ static int dw_spi_dma_init_mfld(struct device *dev, struct dw_spi *dws)
 	struct dw_dma_slave dma_rx = { .src_id = 0 }, *rx = &dma_rx;
 	struct pci_dev *dma_dev;
 	dma_cap_mask_t mask;
+	int ret = -EBUSY;
 
 	/*
 	 * Get pci device for DMA controller, currently it could only
@@ -124,20 +135,25 @@ static int dw_spi_dma_init_mfld(struct device *dev, struct dw_spi *dws)
 
 	init_completion(&dws->dma_completion);
 
-	dw_spi_dma_maxburst_init(dws);
+	ret = dw_spi_dma_caps_init(dws);
+	if (ret)
+		goto free_txchan;
 
-	dw_spi_dma_sg_burst_init(dws);
+	dw_spi_dma_maxburst_init(dws);
 
 	pci_dev_put(dma_dev);
 
 	return 0;
 
+free_txchan:
+	dma_release_channel(dws->txchan);
+	dws->txchan = NULL;
 free_rxchan:
 	dma_release_channel(dws->rxchan);
 	dws->rxchan = NULL;
 err_exit:
 	pci_dev_put(dma_dev);
-	return -EBUSY;
+	return ret;
 }
 
 static int dw_spi_dma_init_generic(struct device *dev, struct dw_spi *dws)
@@ -163,12 +179,17 @@ static int dw_spi_dma_init_generic(struct device *dev, struct dw_spi *dws)
 
 	init_completion(&dws->dma_completion);
 
-	dw_spi_dma_maxburst_init(dws);
+	ret = dw_spi_dma_caps_init(dws);
+	if (ret)
+		goto free_txchan;
 
-	dw_spi_dma_sg_burst_init(dws);
+	dw_spi_dma_maxburst_init(dws);
 
 	return 0;
 
+free_txchan:
+	dma_release_channel(dws->txchan);
+	dws->txchan = NULL;
 free_rxchan:
 	dma_release_channel(dws->rxchan);
 	dws->rxchan = NULL;
-- 
2.40.0.634.g4ca3ef3211-goog

[PATCH v6 4/5] spi: dw: Add DMA address widths capability check

[Joy Chakraborty]

Store address width capabilities of DMA controller during init and check
the same per transfer to make sure the bits/word requirement can be met.

Current DW DMA driver requires both tx and rx channel to be configured
and functional hence a subset of both tx and rx channel address width
capability is checked with the width requirement(n_bytes) for a
transfer.

Signed-off-by: Joy Chakraborty <joychakr@google.com>
---
 drivers/spi/spi-dw-dma.c | 17 +++++++++++++++--
 drivers/spi/spi-dw.h     |  1 +
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-dw-dma.c b/drivers/spi/spi-dw-dma.c
index e1dd13fe4fd0..45980c46946d 100644
--- a/drivers/spi/spi-dw-dma.c
+++ b/drivers/spi/spi-dw-dma.c
@@ -97,6 +97,14 @@ static int dw_spi_dma_caps_init(struct dw_spi *dws)
 		dws->dma_sg_burst = rx.max_sg_burst;
 	else
 		dws->dma_sg_burst = 0;
+
+	/*
+	 * Assuming both channels belong to the same DMA controller hence the
+	 * address width capabilities most likely would be the same.
+	 */
+	dws->dma_addr_widths = tx.dst_addr_widths & rx.src_addr_widths;
+
+	return 0;
 }
 
 static int dw_spi_dma_init_mfld(struct device *dev, struct dw_spi *dws)
@@ -237,10 +245,15 @@ static bool dw_spi_can_dma(struct spi_controller *master,
 			   struct spi_device *spi, struct spi_transfer *xfer)
 {
 	struct dw_spi *dws = spi_controller_get_devdata(master);
+	enum dma_slave_buswidth dma_bus_width;
 
-	return xfer->len > dws->fifo_len;
-}
+	if (xfer->len <= dws->fifo_len)
+		return false;
 
+	dma_bus_width = dw_spi_dma_convert_width(dws->n_bytes);
+
+	return dws->dma_addr_widths & BIT(dma_bus_width);
+}
 
 static int dw_spi_dma_wait(struct dw_spi *dws, unsigned int len, u32 speed)
 {
diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
index 9e8eb2b52d5c..3962e6dcf880 100644
--- a/drivers/spi/spi-dw.h
+++ b/drivers/spi/spi-dw.h
@@ -190,6 +190,7 @@ struct dw_spi {
 	struct dma_chan		*rxchan;
 	u32			rxburst;
 	u32			dma_sg_burst;
+	u32			dma_addr_widths;
 	unsigned long		dma_chan_busy;
 	dma_addr_t		dma_addr; /* phy address of the Data register */
 	const struct dw_spi_dma_ops *dma_ops;
-- 
2.40.0.634.g4ca3ef3211-goog

[PATCH v6 5/5] spi: dw: Round of n_bytes to power of 2

[Joy Chakraborty]

n_bytes variable in the driver represents the number of bytes per word
that needs to be sent/copied to fifo. Bits/word can be between 8 and 32
bits from the client but in memory they are a power of 2, same is mentioned
in spi.h header:
"
 * @bits_per_word: Data transfers involve one or more words; word sizes
 *	like eight or 12 bits are common.  In-memory wordsizes are
 *	powers of two bytes (e.g. 20 bit samples use 32 bits).
 *	This may be changed by the device's driver, or left at the
 *	default (0) indicating protocol words are eight bit bytes.
 *	The spi_transfer.bits_per_word can override this for each transfer.
"

Hence, round of n_bytes to a power of 2 to avoid values like 3 which
would generate unalligned/odd accesses to memory/fifo.

Fixes: a51acc2400d4 ("spi: dw: Add support for 32-bits max xfer size")
Suggested-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Joy Chakraborty <joychakr@google.com>
---
 drivers/spi/spi-dw-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
index c3bfb6c84cab..a6486db46c61 100644
--- a/drivers/spi/spi-dw-core.c
+++ b/drivers/spi/spi-dw-core.c
@@ -426,7 +426,7 @@ static int dw_spi_transfer_one(struct spi_controller *master,
 	int ret;
 
 	dws->dma_mapped = 0;
-	dws->n_bytes = DIV_ROUND_UP(transfer->bits_per_word, BITS_PER_BYTE);
+	dws->n_bytes = roundup_pow_of_two(DIV_ROUND_UP(transfer->bits_per_word, BITS_PER_BYTE));
 	dws->tx = (void *)transfer->tx_buf;
 	dws->tx_len = transfer->len / dws->n_bytes;
 	dws->rx = transfer->rx_buf;
-- 
2.40.0.634.g4ca3ef3211-goog

Re: [PATCH v6 2/5] spi: dw: Move "dw_spi_can_dma" function

[Andy Shevchenko]

On Fri, Apr 14, 2023 at 12:05:17PM +0000, Joy Chakraborty wrote:
> Move "dw_spi_can_dma" function implementation below
> "dw_spi_dma_convert_width" function for handing compile dependency in
> future patches.

We refer to the functions like func().

...

> +static bool dw_spi_can_dma(struct spi_controller *master,
> +			   struct spi_device *spi, struct spi_transfer *xfer)
> +{
> +	struct dw_spi *dws = spi_controller_get_devdata(master);
> +
> +	return xfer->len > dws->fifo_len;
> +}

> +
> +

Single blank line is enough.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v6 2/5] spi: dw: Move "dw_spi_can_dma" function

[Joy Chakraborty]

On Mon, Apr 17, 2023 at 4:13 PM Andy Shevchenko
<andriy.shevchenko@intel.com> wrote:
>
> On Fri, Apr 14, 2023 at 12:05:17PM +0000, Joy Chakraborty wrote:
> > Move "dw_spi_can_dma" function implementation below
> > "dw_spi_dma_convert_width" function for handing compile dependency in
> > future patches.
>
> We refer to the functions like func().
>
> ...
>
> > +static bool dw_spi_can_dma(struct spi_controller *master,
> > +                        struct spi_device *spi, struct spi_transfer *xfer)
> > +{
> > +     struct dw_spi *dws = spi_controller_get_devdata(master);
> > +
> > +     return xfer->len > dws->fifo_len;
> > +}
>
> > +
> > +
>
> Single blank line is enough.

Sure,I will make these changes and send V7.
Will wait for some time to see if Serge(y) has any other comments on
the patch series.

>
> --
> With Best Regards,
> Andy Shevchenko
>
>

Re: [PATCH v6 4/5] spi: dw: Add DMA address widths capability check

[Andy Shevchenko]

On Fri, Apr 14, 2023 at 12:05:19PM +0000, Joy Chakraborty wrote:
> Store address width capabilities of DMA controller during init and check
> the same per transfer to make sure the bits/word requirement can be met.
> 
> Current DW DMA driver requires both tx and rx channel to be configured
> and functional hence a subset of both tx and rx channel address width
> capability is checked with the width requirement(n_bytes) for a
> transfer.

...

> +	/*
> +	 * Assuming both channels belong to the same DMA controller hence the
> +	 * address width capabilities most likely would be the same.

I would add something to explain the side of these address width, like

	 * Assuming both channels belong to the same DMA controller hence
	 * the peripheral side address width capabilities most likely would
	 * be the same.

> +	 */

-- 
With Best Regards,
Andy Shevchenko