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From:   Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
To:     agross@kernel.org, andersson@kernel.org, konrad.dybcio@linaro.org,
        broonie@kernel.org, linux-arm-msm@vger.kernel.org,
        linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     quic_msavaliy@quicinc.com, dianders@chromium.org, mka@chromium.org,
        swboyd@chromium.org, quic_vtanuku@quicinc.com, vkoul@kernel.org,
        Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
Subject: [V3] spi: spi-geni-qcom: Add support for SE DMA mode
Date:   Tue, 29 Nov 2022 14:53:34 +0530
Message-Id: <1669713814-28876-1-git-send-email-quic_vnivarth@quicinc.com>
Precedence: bulk

SE DMA mode can be used for larger transfers and FIFO mode
for smaller transfers.

Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
---
v2 -> v3:
- indentation change
- readability change

v1 -> v2:
- replace writel_relaxed with writel
- corrected order of performing FSM reset and dma_unprep
- added more comments in geni_can_dma
- removed redundant change in spi_geni_init(DMA as default xfer_mode)
- removed redundant initialisations in setup_se_xfer
- removed redundant null checks in setup_se_xfer
- added dma_tx_prep failure handling(rx un_map) in setup_se_xfer
- move handing return of setip_se_xfer to transfer_one
- apply irq error handling for DMA mode too in geni_spi_isr
---
 drivers/spi/spi-geni-qcom.c | 211 ++++++++++++++++++++++++++++++++++----------
 1 file changed, 165 insertions(+), 46 deletions(-)

diff --git a/drivers/spi/spi-geni-qcom.c b/drivers/spi/spi-geni-qcom.c
index 4e83cc5..170c0cb 100644
--- a/drivers/spi/spi-geni-qcom.c
+++ b/drivers/spi/spi-geni-qcom.c
@@ -87,6 +87,8 @@ struct spi_geni_master {
 	struct completion cs_done;
 	struct completion cancel_done;
 	struct completion abort_done;
+	struct completion tx_reset_done;
+	struct completion rx_reset_done;
 	unsigned int oversampling;
 	spinlock_t lock;
 	int irq;
@@ -95,6 +97,7 @@ struct spi_geni_master {
 	struct dma_chan *tx;
 	struct dma_chan *rx;
 	int cur_xfer_mode;
+	u32 cur_m_cmd;
 };
 
 static int get_spi_clk_cfg(unsigned int speed_hz,
@@ -129,23 +132,27 @@ static int get_spi_clk_cfg(unsigned int speed_hz,
 	return ret;
 }
 
-static void handle_fifo_timeout(struct spi_master *spi,
+static void handle_se_timeout(struct spi_master *spi,
 				struct spi_message *msg)
 {
 	struct spi_geni_master *mas = spi_master_get_devdata(spi);
 	unsigned long time_left;
 	struct geni_se *se = &mas->se;
+	const struct spi_transfer *xfer;
 
 	spin_lock_irq(&mas->lock);
 	reinit_completion(&mas->cancel_done);
-	writel(0, se->base + SE_GENI_TX_WATERMARK_REG);
+	if (mas->cur_xfer_mode == GENI_SE_FIFO)
+		writel(0, se->base + SE_GENI_TX_WATERMARK_REG);
+
+	xfer = mas->cur_xfer;
 	mas->cur_xfer = NULL;
 	geni_se_cancel_m_cmd(se);
 	spin_unlock_irq(&mas->lock);
 
 	time_left = wait_for_completion_timeout(&mas->cancel_done, HZ);
 	if (time_left)
-		return;
+		goto unmap_if_dma;
 
 	spin_lock_irq(&mas->lock);
 	reinit_completion(&mas->abort_done);
@@ -162,6 +169,45 @@ static void handle_fifo_timeout(struct spi_master *spi,
 		 */
 		mas->abort_failed = true;
 	}
+
+unmap_if_dma:
+	if (mas->cur_xfer_mode == GENI_SE_DMA) {
+		if (mas->cur_m_cmd & SPI_TX_ONLY) {
+			spin_lock_irq(&mas->lock);
+			reinit_completion(&mas->tx_reset_done);
+			writel(1, se->base + SE_DMA_TX_FSM_RST);
+			spin_unlock_irq(&mas->lock);
+			time_left = wait_for_completion_timeout(&mas->tx_reset_done, HZ);
+			if (!time_left)
+				dev_err(mas->dev, "DMA TX RESET failed\n");
+		}
+		if (mas->cur_m_cmd & SPI_RX_ONLY) {
+			spin_lock_irq(&mas->lock);
+			reinit_completion(&mas->rx_reset_done);
+			writel(1, se->base + SE_DMA_RX_FSM_RST);
+			spin_unlock_irq(&mas->lock);
+			time_left = wait_for_completion_timeout(&mas->rx_reset_done, HZ);
+			if (!time_left)
+				dev_err(mas->dev, "DMA RX RESET failed\n");
+		}
+
+		if (xfer) {
+			if (xfer->tx_buf && xfer->tx_dma)
+				geni_se_tx_dma_unprep(se, xfer->tx_dma, xfer->len);
+			if (xfer->rx_buf && xfer->rx_dma)
+				geni_se_rx_dma_unprep(se, xfer->rx_dma, xfer->len);
+		} else {
+			/*
+			 * This can happen if a timeout happened and we had to wait
+			 * for lock in this function because isr was holding the lock
+			 * and handling transfer completion at that time.
+			 * isr will set cur_xfer to NULL when done.
+			 * Unnecessary error but cannot be helped.
+			 * Only do reset, dma_unprep is already done by isr.
+			 */
+			dev_err(mas->dev, "Cancel/Abort on completed SPI transfer\n");
+		}
+	}
 }
 
 static void handle_gpi_timeout(struct spi_master *spi, struct spi_message *msg)
@@ -178,7 +224,8 @@ static void spi_geni_handle_err(struct spi_master *spi, struct spi_message *msg)
 
 	switch (mas->cur_xfer_mode) {
 	case GENI_SE_FIFO:
-		handle_fifo_timeout(spi, msg);
+	case GENI_SE_DMA:
+		handle_se_timeout(spi, msg);
 		break;
 	case GENI_GPI_DMA:
 		handle_gpi_timeout(spi, msg);
@@ -260,7 +307,7 @@ static void spi_geni_set_cs(struct spi_device *slv, bool set_flag)
 	time_left = wait_for_completion_timeout(&mas->cs_done, HZ);
 	if (!time_left) {
 		dev_warn(mas->dev, "Timeout setting chip select\n");
-		handle_fifo_timeout(spi, NULL);
+		handle_se_timeout(spi, NULL);
 	}
 
 exit:
@@ -482,8 +529,12 @@ static bool geni_can_dma(struct spi_controller *ctlr,
 {
 	struct spi_geni_master *mas = spi_master_get_devdata(slv->master);
 
-	/* check if dma is supported */
-	return mas->cur_xfer_mode != GENI_SE_FIFO;
+	/*
+	 * 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;
 }
 
 static int spi_geni_prepare_message(struct spi_master *spi,
@@ -494,6 +545,7 @@ static int spi_geni_prepare_message(struct spi_master *spi,
 
 	switch (mas->cur_xfer_mode) {
 	case GENI_SE_FIFO:
+	case GENI_SE_DMA:
 		if (spi_geni_is_abort_still_pending(mas))
 			return -EBUSY;
 		ret = setup_fifo_params(spi_msg->spi, spi);
@@ -597,7 +649,7 @@ static int spi_geni_init(struct spi_geni_master *mas)
 			break;
 		}
 		/*
-		 * in case of failure to get dma channel, we can still do the
+		 * in case of failure to get gpi dma channel, we can still do the
 		 * FIFO mode, so fallthrough
 		 */
 		dev_warn(mas->dev, "FIFO mode disabled, but couldn't get DMA, fall back to FIFO mode\n");
@@ -716,12 +768,12 @@ static void geni_spi_handle_rx(struct spi_geni_master *mas)
 	mas->rx_rem_bytes -= rx_bytes;
 }
 
-static void setup_fifo_xfer(struct spi_transfer *xfer,
+static int setup_se_xfer(struct spi_transfer *xfer,
 				struct spi_geni_master *mas,
 				u16 mode, struct spi_master *spi)
 {
 	u32 m_cmd = 0;
-	u32 len;
+	u32 len, fifo_size;
 	struct geni_se *se = &mas->se;
 	int ret;
 
@@ -748,7 +800,7 @@ static void setup_fifo_xfer(struct spi_transfer *xfer,
 	/* Speed and bits per word can be overridden per transfer */
 	ret = geni_spi_set_clock_and_bw(mas, xfer->speed_hz);
 	if (ret)
-		return;
+		return ret;
 
 	mas->tx_rem_bytes = 0;
 	mas->rx_rem_bytes = 0;
@@ -771,6 +823,12 @@ static void setup_fifo_xfer(struct spi_transfer *xfer,
 		writel(len, se->base + SE_SPI_RX_TRANS_LEN);
 		mas->rx_rem_bytes = xfer->len;
 	}
+	mas->cur_m_cmd = m_cmd;
+
+	/* 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;
+	geni_se_select_mode(se, mas->cur_xfer_mode);
 
 	/*
 	 * Lock around right before we start the transfer since our
@@ -778,11 +836,39 @@ static void setup_fifo_xfer(struct spi_transfer *xfer,
 	 */
 	spin_lock_irq(&mas->lock);
 	geni_se_setup_m_cmd(se, m_cmd, FRAGMENTATION);
-	if (m_cmd & SPI_TX_ONLY) {
+
+	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, &xfer->rx_dma);
+			if (ret) {
+				dev_err(mas->dev, "Failed to setup Rx dma %d\n", ret);
+				xfer->rx_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, &xfer->tx_dma);
+			if (ret) {
+				dev_err(mas->dev, "Failed to setup Tx dma %d\n", ret);
+				xfer->tx_dma = 0;
+				if (m_cmd & SPI_RX_ONLY && xfer->rx_dma) {
+					/* Unmap rx buffer if duplex transfer */
+					geni_se_rx_dma_unprep(se, xfer->rx_dma, xfer->len);
+					xfer->rx_dma = 0;
+				}
+				goto unlock_and_return;
+			}
+		}
+	} 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;
 }
 
 static int spi_geni_transfer_one(struct spi_master *spi,
@@ -790,6 +876,7 @@ static int spi_geni_transfer_one(struct spi_master *spi,
 				struct spi_transfer *xfer)
 {
 	struct spi_geni_master *mas = spi_master_get_devdata(spi);
+	int ret;
 
 	if (spi_geni_is_abort_still_pending(mas))
 		return -EBUSY;
@@ -798,9 +885,12 @@ static int spi_geni_transfer_one(struct spi_master *spi,
 	if (!xfer->len)
 		return 0;
 
-	if (mas->cur_xfer_mode == GENI_SE_FIFO) {
-		setup_fifo_xfer(xfer, mas, slv->mode, spi);
-		return 1;
+	if (mas->cur_xfer_mode == GENI_SE_FIFO || mas->cur_xfer_mode == GENI_SE_DMA) {
+		ret = setup_se_xfer(xfer, mas, slv->mode, spi);
+		/* SPI framework expects +ve ret code to wait for transfer complete */
+		if (!ret)
+			ret = 1;
+		return ret;
 	}
 	return setup_gsi_xfer(xfer, mas, slv, spi);
 }
@@ -823,39 +913,66 @@ static irqreturn_t geni_spi_isr(int irq, void *data)
 
 	spin_lock(&mas->lock);
 
-	if ((m_irq & M_RX_FIFO_WATERMARK_EN) || (m_irq & M_RX_FIFO_LAST_EN))
-		geni_spi_handle_rx(mas);
-
-	if (m_irq & M_TX_FIFO_WATERMARK_EN)
-		geni_spi_handle_tx(mas);
-
-	if (m_irq & M_CMD_DONE_EN) {
-		if (mas->cur_xfer) {
+	if (mas->cur_xfer_mode == GENI_SE_FIFO) {
+		if ((m_irq & M_RX_FIFO_WATERMARK_EN) || (m_irq & M_RX_FIFO_LAST_EN))
+			geni_spi_handle_rx(mas);
+
+		if (m_irq & M_TX_FIFO_WATERMARK_EN)
+			geni_spi_handle_tx(mas);
+
+		if (m_irq & M_CMD_DONE_EN) {
+			if (mas->cur_xfer) {
+				spi_finalize_current_transfer(spi);
+				mas->cur_xfer = NULL;
+				/*
+				 * If this happens, then a CMD_DONE came before all the
+				 * Tx buffer bytes were sent out. This is unusual, log
+				 * this condition and disable the WM interrupt to
+				 * prevent the system from stalling due an interrupt
+				 * storm.
+				 *
+				 * If this happens when all Rx bytes haven't been
+				 * received, log the condition. The only known time
+				 * this can happen is if bits_per_word != 8 and some
+				 * registers that expect xfer lengths in num spi_words
+				 * weren't written correctly.
+				 */
+				if (mas->tx_rem_bytes) {
+					writel(0, se->base + SE_GENI_TX_WATERMARK_REG);
+					dev_err(mas->dev, "Premature done. tx_rem = %d bpw%d\n",
+						mas->tx_rem_bytes, mas->cur_bits_per_word);
+				}
+				if (mas->rx_rem_bytes)
+					dev_err(mas->dev, "Premature done. rx_rem = %d bpw%d\n",
+						mas->rx_rem_bytes, mas->cur_bits_per_word);
+			} else {
+				complete(&mas->cs_done);
+			}
+		}
+	} else if (mas->cur_xfer_mode == GENI_SE_DMA) {
+		const struct spi_transfer *xfer = mas->cur_xfer;
+		u32 dma_tx_status = readl_relaxed(se->base + SE_DMA_TX_IRQ_STAT);
+		u32 dma_rx_status = readl_relaxed(se->base + SE_DMA_RX_IRQ_STAT);
+
+		if (dma_tx_status)
+			writel(dma_tx_status, se->base + SE_DMA_TX_IRQ_CLR);
+		if (dma_rx_status)
+			writel(dma_rx_status, se->base + SE_DMA_RX_IRQ_CLR);
+		if (dma_tx_status & TX_DMA_DONE)
+			mas->tx_rem_bytes = 0;
+		if (dma_rx_status & RX_DMA_DONE)
+			mas->rx_rem_bytes = 0;
+		if (dma_tx_status & TX_RESET_DONE)
+			complete(&mas->tx_reset_done);
+		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 && xfer->tx_dma)
+				geni_se_tx_dma_unprep(se, xfer->tx_dma, xfer->len);
+			if (xfer->rx_buf && xfer->rx_dma)
+				geni_se_rx_dma_unprep(se, xfer->rx_dma, xfer->len);
 			spi_finalize_current_transfer(spi);
 			mas->cur_xfer = NULL;
-			/*
-			 * If this happens, then a CMD_DONE came before all the
-			 * Tx buffer bytes were sent out. This is unusual, log
-			 * this condition and disable the WM interrupt to
-			 * prevent the system from stalling due an interrupt
-			 * storm.
-			 *
-			 * If this happens when all Rx bytes haven't been
-			 * received, log the condition. The only known time
-			 * this can happen is if bits_per_word != 8 and some
-			 * registers that expect xfer lengths in num spi_words
-			 * weren't written correctly.
-			 */
-			if (mas->tx_rem_bytes) {
-				writel(0, se->base + SE_GENI_TX_WATERMARK_REG);
-				dev_err(mas->dev, "Premature done. tx_rem = %d bpw%d\n",
-					mas->tx_rem_bytes, mas->cur_bits_per_word);
-			}
-			if (mas->rx_rem_bytes)
-				dev_err(mas->dev, "Premature done. rx_rem = %d bpw%d\n",
-					mas->rx_rem_bytes, mas->cur_bits_per_word);
-		} else {
-			complete(&mas->cs_done);
 		}
 	}
 
@@ -949,6 +1066,8 @@ static int spi_geni_probe(struct platform_device *pdev)
 	init_completion(&mas->cs_done);
 	init_completion(&mas->cancel_done);
 	init_completion(&mas->abort_done);
+	init_completion(&mas->tx_reset_done);
+	init_completion(&mas->rx_reset_done);
 	spin_lock_init(&mas->lock);
 	pm_runtime_use_autosuspend(&pdev->dev);
 	pm_runtime_set_autosuspend_delay(&pdev->dev, 250);
-- 
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