[v2,2/2] spi: spi-geni-qcom: Do not do DMA map/unmap inside driver, use framework instead

  The spi geni driver in SE DMA mode, unlike GSI DMA, is not making use of
DMA mapping functionality available in the framework.
The driver does mapping internally which makes dma buffer fields available
in spi_transfer struct superfluous while requiring additional members in
spi_geni_master struct.

Conform to the design by having framework handle map/unmap and do only
DMA transfer in the driver; this also simplifies code a bit.

Fixes: e5f0dfa78ac7 ("spi: spi-geni-qcom: Add support for SE DMA mode")
Suggested-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
---
v1 -> v2:
- pass dma address to new geni interfaces instead of pointer
- set max_dma_len as per HPG
- remove expendable local variables
---
 drivers/spi/spi-geni-qcom.c | 103 +++++++++++++++++++++-----------------------
 1 file changed, 50 insertions(+), 53 deletions(-)
  

Hi,

On Wed, May 17, 2023 at 5:18 AM Vijaya Krishna Nivarthi
<quic_vnivarth@quicinc.com> wrote:
>
> The spi geni driver in SE DMA mode, unlike GSI DMA, is not making use of
> DMA mapping functionality available in the framework.
> The driver does mapping internally which makes dma buffer fields available
> in spi_transfer struct superfluous while requiring additional members in
> spi_geni_master struct.
>
> Conform to the design by having framework handle map/unmap and do only
> DMA transfer in the driver; this also simplifies code a bit.
>
> Fixes: e5f0dfa78ac7 ("spi: spi-geni-qcom: Add support for SE DMA mode")

I'm not 100% sure I'd tag it as a fix. It's certainly a cleanup that
was asked for when thuat patch was landed, but technically it doesn't
fix any known problems. In any case, I'll leave it to Mark to decide
if he's happy with the fixes tag and to remove it if he sees fit. IMO
no need to re-post the patch either way.


> Suggested-by: Douglas Anderson <dianders@chromium.org>
> Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
> ---
> v1 -> v2:
> - pass dma address to new geni interfaces instead of pointer
> - set max_dma_len as per HPG
> - remove expendable local variables
> ---
>  drivers/spi/spi-geni-qcom.c | 103 +++++++++++++++++++++-----------------------
>  1 file changed, 50 insertions(+), 53 deletions(-)

Mark and Bjorn will have to coordinate how they want to land this,
since normally patch #1 would go through the Qualcomm tree and patch
#2 through the SPI tree. In any case:

Reviewed-by: Douglas Anderson <dianders@chromium.org>
  

On 17.05.2023 14:18, Vijaya Krishna Nivarthi wrote:
> The spi geni driver in SE DMA mode, unlike GSI DMA, is not making use of
> DMA mapping functionality available in the framework.
> The driver does mapping internally which makes dma buffer fields available
> in spi_transfer struct superfluous while requiring additional members in
> spi_geni_master struct.
> 
> Conform to the design by having framework handle map/unmap and do only
> DMA transfer in the driver; this also simplifies code a bit.
> 
> Fixes: e5f0dfa78ac7 ("spi: spi-geni-qcom: Add support for SE DMA mode")
> Suggested-by: Douglas Anderson <dianders@chromium.org>
> Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
> ---
I don't really have a good insight in this code, but these changes
seem sane.

Acked-by: Konrad Dybcio <konrad.dybcio@linaro.org>

Konrad
> v1 -> v2:
> - pass dma address to new geni interfaces instead of pointer
> - set max_dma_len as per HPG
> - remove expendable local variables
> ---
>  drivers/spi/spi-geni-qcom.c | 103 +++++++++++++++++++++-----------------------
>  1 file changed, 50 insertions(+), 53 deletions(-)
> 
> diff --git a/drivers/spi/spi-geni-qcom.c b/drivers/spi/spi-geni-qcom.c
> index e423efc..206cc04 100644
> --- a/drivers/spi/spi-geni-qcom.c
> +++ b/drivers/spi/spi-geni-qcom.c
> @@ -97,8 +97,6 @@ struct spi_geni_master {
>  	struct dma_chan *tx;
>  	struct dma_chan *rx;
>  	int cur_xfer_mode;
> -	dma_addr_t tx_se_dma;
> -	dma_addr_t rx_se_dma;
>  };
>  
>  static int get_spi_clk_cfg(unsigned int speed_hz,
> @@ -174,7 +172,7 @@ static void handle_se_timeout(struct spi_master *spi,
>  unmap_if_dma:
>  	if (mas->cur_xfer_mode == GENI_SE_DMA) {
>  		if (xfer) {
> -			if (xfer->tx_buf && mas->tx_se_dma) {
> +			if (xfer->tx_buf) {
>  				spin_lock_irq(&mas->lock);
>  				reinit_completion(&mas->tx_reset_done);
>  				writel(1, se->base + SE_DMA_TX_FSM_RST);
> @@ -182,9 +180,8 @@ static void handle_se_timeout(struct spi_master *spi,
>  				time_left = wait_for_completion_timeout(&mas->tx_reset_done, HZ);
>  				if (!time_left)
>  					dev_err(mas->dev, "DMA TX RESET failed\n");
> -				geni_se_tx_dma_unprep(se, mas->tx_se_dma, xfer->len);
>  			}
> -			if (xfer->rx_buf && mas->rx_se_dma) {
> +			if (xfer->rx_buf) {
>  				spin_lock_irq(&mas->lock);
>  				reinit_completion(&mas->rx_reset_done);
>  				writel(1, se->base + SE_DMA_RX_FSM_RST);
> @@ -192,7 +189,6 @@ static void handle_se_timeout(struct spi_master *spi,
>  				time_left = wait_for_completion_timeout(&mas->rx_reset_done, HZ);
>  				if (!time_left)
>  					dev_err(mas->dev, "DMA RX RESET failed\n");
> -				geni_se_rx_dma_unprep(se, mas->rx_se_dma, xfer->len);
>  			}
>  		} else {
>  			/*
> @@ -523,17 +519,36 @@ static int setup_gsi_xfer(struct spi_transfer *xfer, struct spi_geni_master *mas
>  	return 1;
>  }
>  
> +static u32 get_xfer_len_in_words(struct spi_transfer *xfer,
> +				struct spi_geni_master *mas)
> +{
> +	u32 len;
> +
> +	if (!(mas->cur_bits_per_word % MIN_WORD_LEN))
> +		len = xfer->len * BITS_PER_BYTE / mas->cur_bits_per_word;
> +	else
> +		len = xfer->len / (mas->cur_bits_per_word / BITS_PER_BYTE + 1);
> +	len &= TRANS_LEN_MSK;
> +
> +	return len;
> +}
> +
>  static bool geni_can_dma(struct spi_controller *ctlr,
>  			 struct spi_device *slv, struct spi_transfer *xfer)
>  {
>  	struct spi_geni_master *mas = spi_master_get_devdata(slv->master);
> +	u32 len, fifo_size;
>  
> -	/*
> -	 * Return true if transfer needs to be mapped prior to
> -	 * calling transfer_one which is the case only for GPI_DMA.
> -	 * For SE_DMA mode, map/unmap is done in geni_se_*x_dma_prep.
> -	 */
> -	return mas->cur_xfer_mode == GENI_GPI_DMA;
> +	if (mas->cur_xfer_mode == GENI_GPI_DMA)
> +		return true;
> +
> +	len = get_xfer_len_in_words(xfer, mas);
> +	fifo_size = mas->tx_fifo_depth * mas->fifo_width_bits / mas->cur_bits_per_word;
> +
> +	if (len > fifo_size)
> +		return true;
> +	else
> +		return false;
>  }
>  
>  static int spi_geni_prepare_message(struct spi_master *spi,
> @@ -772,7 +787,7 @@ static int setup_se_xfer(struct spi_transfer *xfer,
>  				u16 mode, struct spi_master *spi)
>  {
>  	u32 m_cmd = 0;
> -	u32 len, fifo_size;
> +	u32 len;
>  	struct geni_se *se = &mas->se;
>  	int ret;
>  
> @@ -804,11 +819,7 @@ static int setup_se_xfer(struct spi_transfer *xfer,
>  	mas->tx_rem_bytes = 0;
>  	mas->rx_rem_bytes = 0;
>  
> -	if (!(mas->cur_bits_per_word % MIN_WORD_LEN))
> -		len = xfer->len * BITS_PER_BYTE / mas->cur_bits_per_word;
> -	else
> -		len = xfer->len / (mas->cur_bits_per_word / BITS_PER_BYTE + 1);
> -	len &= TRANS_LEN_MSK;
> +	len = get_xfer_len_in_words(xfer, mas);
>  
>  	mas->cur_xfer = xfer;
>  	if (xfer->tx_buf) {
> @@ -823,9 +834,20 @@ static int setup_se_xfer(struct spi_transfer *xfer,
>  		mas->rx_rem_bytes = xfer->len;
>  	}
>  
> -	/* Select transfer mode based on transfer length */
> -	fifo_size = mas->tx_fifo_depth * mas->fifo_width_bits / mas->cur_bits_per_word;
> -	mas->cur_xfer_mode = (len <= fifo_size) ? GENI_SE_FIFO : GENI_SE_DMA;
> +	/*
> +	 * Select DMA mode if sgt are present; and with only 1 entry
> +	 * This is not a serious limitation because the xfer buffers are
> +	 * expected to fit into in 1 entry almost always, and if any
> +	 * doesn't for any reason we fall back to FIFO mode anyway
> +	 */
> +	if (!xfer->tx_sg.nents && !xfer->rx_sg.nents)
> +		mas->cur_xfer_mode = GENI_SE_FIFO;
> +	else if (xfer->tx_sg.nents > 1 || xfer->rx_sg.nents > 1) {
> +		dev_warn_once(mas->dev, "Doing FIFO, cannot handle tx_nents-%d, rx_nents-%d\n",
> +			xfer->tx_sg.nents, xfer->rx_sg.nents);
> +		mas->cur_xfer_mode = GENI_SE_FIFO;
> +	} else
> +		mas->cur_xfer_mode = GENI_SE_DMA;
>  	geni_se_select_mode(se, mas->cur_xfer_mode);
>  
>  	/*
> @@ -836,35 +858,17 @@ static int setup_se_xfer(struct spi_transfer *xfer,
>  	geni_se_setup_m_cmd(se, m_cmd, FRAGMENTATION);
>  
>  	if (mas->cur_xfer_mode == GENI_SE_DMA) {
> -		if (m_cmd & SPI_RX_ONLY) {
> -			ret =  geni_se_rx_dma_prep(se, xfer->rx_buf,
> -				xfer->len, &mas->rx_se_dma);
> -			if (ret) {
> -				dev_err(mas->dev, "Failed to setup Rx dma %d\n", ret);
> -				mas->rx_se_dma = 0;
> -				goto unlock_and_return;
> -			}
> -		}
> -		if (m_cmd & SPI_TX_ONLY) {
> -			ret =  geni_se_tx_dma_prep(se, (void *)xfer->tx_buf,
> -				xfer->len, &mas->tx_se_dma);
> -			if (ret) {
> -				dev_err(mas->dev, "Failed to setup Tx dma %d\n", ret);
> -				mas->tx_se_dma = 0;
> -				if (m_cmd & SPI_RX_ONLY) {
> -					/* Unmap rx buffer if duplex transfer */
> -					geni_se_rx_dma_unprep(se, mas->rx_se_dma, xfer->len);
> -					mas->rx_se_dma = 0;
> -				}
> -				goto unlock_and_return;
> -			}
> -		}
> +		if (m_cmd & SPI_RX_ONLY)
> +			geni_se_rx_init_dma(se, sg_dma_address(xfer->rx_sg.sgl),
> +				sg_dma_len(xfer->rx_sg.sgl));
> +		if (m_cmd & SPI_TX_ONLY)
> +			geni_se_tx_init_dma(se, sg_dma_address(xfer->tx_sg.sgl),
> +				sg_dma_len(xfer->tx_sg.sgl));
>  	} else if (m_cmd & SPI_TX_ONLY) {
>  		if (geni_spi_handle_tx(mas))
>  			writel(mas->tx_wm, se->base + SE_GENI_TX_WATERMARK_REG);
>  	}
>  
> -unlock_and_return:
>  	spin_unlock_irq(&mas->lock);
>  	return ret;
>  }
> @@ -965,14 +969,6 @@ static irqreturn_t geni_spi_isr(int irq, void *data)
>  		if (dma_rx_status & RX_RESET_DONE)
>  			complete(&mas->rx_reset_done);
>  		if (!mas->tx_rem_bytes && !mas->rx_rem_bytes && xfer) {
> -			if (xfer->tx_buf && mas->tx_se_dma) {
> -				geni_se_tx_dma_unprep(se, mas->tx_se_dma, xfer->len);
> -				mas->tx_se_dma = 0;
> -			}
> -			if (xfer->rx_buf && mas->rx_se_dma) {
> -				geni_se_rx_dma_unprep(se, mas->rx_se_dma, xfer->len);
> -				mas->rx_se_dma = 0;
> -			}
>  			spi_finalize_current_transfer(spi);
>  			mas->cur_xfer = NULL;
>  		}
> @@ -1057,6 +1053,7 @@ static int spi_geni_probe(struct platform_device *pdev)
>  	spi->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 32);
>  	spi->num_chipselect = 4;
>  	spi->max_speed_hz = 50000000;
> +	spi->max_dma_len = 0xffff0; /* 24 bits for tx/rx dma length */
>  	spi->prepare_message = spi_geni_prepare_message;
>  	spi->transfer_one = spi_geni_transfer_one;
>  	spi->can_dma = geni_can_dma;