spi: pxa2xx: Use core message processing loop

Convert the pump_transfers() transfer tasklet to transfer_one() hook the
SPI core calls to process single transfer instead of handling message
processing and chip select handling in the driver. This not only
simplifies the driver but also brings transfer statistics from the core.
Signed-off-by: NJarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

drivers/spi/spi-pxa2xx-dma.c

@@ -51,19 +51,15 @@ static void pxa2xx_spi_dma_transfer_complete(struct driver_data *drv_data,
 		if (!pxa25x_ssp_comp(drv_data))
 			pxa2xx_spi_write(drv_data, SSTO, 0);
 
-		if (!error) {
-			msg->actual_length += drv_data->len;
-			msg->state = pxa2xx_spi_next_transfer(drv_data);
-		} else {
+		if (error) {
 			/* In case we got an error we disable the SSP now */
 			pxa2xx_spi_write(drv_data, SSCR0,
 					 pxa2xx_spi_read(drv_data, SSCR0)
 					 & ~SSCR0_SSE);
-
-			msg->state = ERROR_STATE;
+			msg->status = -EIO;
 		}
 
-		tasklet_schedule(&drv_data->pump_transfers);
+		spi_finalize_current_transfer(drv_data->master);
 	}
 }
 
@@ -74,11 +70,11 @@ static void pxa2xx_spi_dma_callback(void *data)
 
 static struct dma_async_tx_descriptor *
 pxa2xx_spi_dma_prepare_one(struct driver_data *drv_data,
-			   enum dma_transfer_direction dir)
+			   enum dma_transfer_direction dir,
+			   struct spi_transfer *xfer)
 {
 	struct chip_data *chip =
 		spi_get_ctldata(drv_data->master->cur_msg->spi);
-	struct spi_transfer *xfer = drv_data->cur_transfer;
 	enum dma_slave_buswidth width;
 	struct dma_slave_config cfg;
 	struct dma_chan *chan;
@@ -144,12 +140,13 @@ irqreturn_t pxa2xx_spi_dma_transfer(struct driver_data *drv_data)
 	return IRQ_NONE;
 }
 
-int pxa2xx_spi_dma_prepare(struct driver_data *drv_data)
+int pxa2xx_spi_dma_prepare(struct driver_data *drv_data,
+			   struct spi_transfer *xfer)
 {
 	struct dma_async_tx_descriptor *tx_desc, *rx_desc;
 	int err;
 
-	tx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_MEM_TO_DEV);
+	tx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_MEM_TO_DEV, xfer);
 	if (!tx_desc) {
 		dev_err(&drv_data->pdev->dev,
 			"failed to get DMA TX descriptor\n");
@@ -157,7 +154,7 @@ int pxa2xx_spi_dma_prepare(struct driver_data *drv_data)
 		goto err_tx;
 	}
 
-	rx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_DEV_TO_MEM);
+	rx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_DEV_TO_MEM, xfer);
 	if (!rx_desc) {
 		dev_err(&drv_data->pdev->dev,
 			"failed to get DMA RX descriptor\n");
@@ -187,6 +184,13 @@ void pxa2xx_spi_dma_start(struct driver_data *drv_data)
 	atomic_set(&drv_data->dma_running, 1);
 }
 
+void pxa2xx_spi_dma_stop(struct driver_data *drv_data)
+{
+	atomic_set(&drv_data->dma_running, 0);
+	dmaengine_terminate_sync(drv_data->master->dma_rx);
+	dmaengine_terminate_sync(drv_data->master->dma_tx);
+}
+
 int pxa2xx_spi_dma_setup(struct driver_data *drv_data)
 {
 	struct pxa2xx_spi_master *pdata = drv_data->master_info;

drivers/spi/spi-pxa2xx.c

@@ -340,9 +340,11 @@ static void lpss_ssp_setup(struct driver_data *drv_data)
 	}
 }
 
-static void lpss_ssp_select_cs(struct driver_data *drv_data,
+static void lpss_ssp_select_cs(struct spi_device *spi,
 			       const struct lpss_config *config)
 {
+	struct driver_data *drv_data =
+		spi_controller_get_devdata(spi->controller);
 	u32 value, cs;
 
 	if (!config->cs_sel_mask)
@@ -350,7 +352,7 @@ static void lpss_ssp_select_cs(struct driver_data *drv_data,
 
 	value = __lpss_ssp_read_priv(drv_data, config->reg_cs_ctrl);
 
-	cs = drv_data->master->cur_msg->spi->chip_select;
+	cs = spi->chip_select;
 	cs <<= config->cs_sel_shift;
 	if (cs != (value & config->cs_sel_mask)) {
 		/*
@@ -369,15 +371,17 @@ static void lpss_ssp_select_cs(struct driver_data *drv_data,
 	}
 }
 
-static void lpss_ssp_cs_control(struct driver_data *drv_data, bool enable)
+static void lpss_ssp_cs_control(struct spi_device *spi, bool enable)
 {
+	struct driver_data *drv_data =
+		spi_controller_get_devdata(spi->controller);
 	const struct lpss_config *config;
 	u32 value;
 
 	config = lpss_get_config(drv_data);
 
 	if (enable)
-		lpss_ssp_select_cs(drv_data, config);
+		lpss_ssp_select_cs(spi, config);
 
 	value = __lpss_ssp_read_priv(drv_data, config->reg_cs_ctrl);
 	if (enable)
@@ -387,10 +391,11 @@ static void lpss_ssp_cs_control(struct driver_data *drv_data, bool enable)
 	__lpss_ssp_write_priv(drv_data, config->reg_cs_ctrl, value);
 }
 
-static void cs_assert(struct driver_data *drv_data)
+static void cs_assert(struct spi_device *spi)
 {
-	struct chip_data *chip =
-		spi_get_ctldata(drv_data->master->cur_msg->spi);
+	struct chip_data *chip = spi_get_ctldata(spi);
+	struct driver_data *drv_data =
+		spi_controller_get_devdata(spi->controller);
 
 	if (drv_data->ssp_type == CE4100_SSP) {
 		pxa2xx_spi_write(drv_data, SSSR, chip->frm);
@@ -408,13 +413,14 @@ static void cs_assert(struct driver_data *drv_data)
 	}
 
 	if (is_lpss_ssp(drv_data))
-		lpss_ssp_cs_control(drv_data, true);
+		lpss_ssp_cs_control(spi, true);
 }
 
-static void cs_deassert(struct driver_data *drv_data)
+static void cs_deassert(struct spi_device *spi)
 {
-	struct chip_data *chip =
-		spi_get_ctldata(drv_data->master->cur_msg->spi);
+	struct chip_data *chip = spi_get_ctldata(spi);
+	struct driver_data *drv_data =
+		spi_controller_get_devdata(spi->controller);
 	unsigned long timeout;
 
 	if (drv_data->ssp_type == CE4100_SSP)
@@ -437,7 +443,15 @@ static void cs_deassert(struct driver_data *drv_data)
 	}
 
 	if (is_lpss_ssp(drv_data))
-		lpss_ssp_cs_control(drv_data, false);
+		lpss_ssp_cs_control(spi, false);
+}
+
+static void pxa2xx_spi_set_cs(struct spi_device *spi, bool level)
+{
+	if (level)
+		cs_deassert(spi);
+	else
+		cs_assert(spi);
 }
 
 int pxa2xx_spi_flush(struct driver_data *drv_data)
@@ -549,70 +563,6 @@ static int u32_reader(struct driver_data *drv_data)
 	return drv_data->rx == drv_data->rx_end;
 }
 
-void *pxa2xx_spi_next_transfer(struct driver_data *drv_data)
-{
-	struct spi_message *msg = drv_data->master->cur_msg;
-	struct spi_transfer *trans = drv_data->cur_transfer;
-
-	/* Move to next transfer */
-	if (trans->transfer_list.next != &msg->transfers) {
-		drv_data->cur_transfer =
-			list_entry(trans->transfer_list.next,
-					struct spi_transfer,
-					transfer_list);
-		return RUNNING_STATE;
-	} else
-		return DONE_STATE;
-}
-
-/* caller already set message->status; dma and pio irqs are blocked */
-static void giveback(struct driver_data *drv_data)
-{
-	struct spi_transfer* last_transfer;
-	struct spi_message *msg;
-
-	msg = drv_data->master->cur_msg;
-	drv_data->cur_transfer = NULL;
-
-	last_transfer = list_last_entry(&msg->transfers, struct spi_transfer,
-					transfer_list);
-
-	/* Delay if requested before any change in chip select */
-	if (last_transfer->delay_usecs)
-		udelay(last_transfer->delay_usecs);
-
-	/* Drop chip select UNLESS cs_change is true or we are returning
-	 * a message with an error, or next message is for another chip
-	 */
-	if (!last_transfer->cs_change)
-		cs_deassert(drv_data);
-	else {
-		struct spi_message *next_msg;
-
-		/* Holding of cs was hinted, but we need to make sure
-		 * the next message is for the same chip.  Don't waste
-		 * time with the following tests unless this was hinted.
-		 *
-		 * We cannot postpone this until pump_messages, because
-		 * after calling msg->complete (below) the driver that
-		 * sent the current message could be unloaded, which
-		 * could invalidate the cs_control() callback...
-		 */
-
-		/* get a pointer to the next message, if any */
-		next_msg = spi_get_next_queued_message(drv_data->master);
-
-		/* see if the next and current messages point
-		 * to the same chip
-		 */
-		if ((next_msg && next_msg->spi != msg->spi) ||
-		    msg->state == ERROR_STATE)
-			cs_deassert(drv_data);
-	}
-
-	spi_finalize_current_message(drv_data->master);
-}
-
 static void reset_sccr1(struct driver_data *drv_data)
 {
 	struct chip_data *chip =
@@ -648,8 +598,8 @@ static void int_error_stop(struct driver_data *drv_data, const char* msg)
 
 	dev_err(&drv_data->pdev->dev, "%s\n", msg);
 
-	drv_data->master->cur_msg->state = ERROR_STATE;
-	tasklet_schedule(&drv_data->pump_transfers);
+	drv_data->master->cur_msg->status = -EIO;
+	spi_finalize_current_transfer(drv_data->master);
 }
 
 static void int_transfer_complete(struct driver_data *drv_data)
@@ -660,19 +610,7 @@ static void int_transfer_complete(struct driver_data *drv_data)
 	if (!pxa25x_ssp_comp(drv_data))
 		pxa2xx_spi_write(drv_data, SSTO, 0);
 
-	/* Update total byte transferred return count actual bytes read */
-	drv_data->master->cur_msg->actual_length += drv_data->len -
-				(drv_data->rx_end - drv_data->rx);
-
-	/* Transfer delays and chip select release are
-	 * handled in pump_transfers or giveback
-	 */
-
-	/* Move to next transfer */
-	drv_data->master->cur_msg->state = pxa2xx_spi_next_transfer(drv_data);
-
-	/* Schedule transfer tasklet */
-	tasklet_schedule(&drv_data->pump_transfers);
+	spi_finalize_current_transfer(drv_data->master);
 }
 
 static irqreturn_t interrupt_transfer(struct driver_data *drv_data)
@@ -973,17 +911,16 @@ static bool pxa2xx_spi_can_dma(struct spi_controller *master,
 	       xfer->len >= chip->dma_burst_size;
 }
 
-static void pump_transfers(unsigned long data)
+int pxa2xx_spi_transfer_one(struct spi_controller *master,
+			    struct spi_device *spi,
+			    struct spi_transfer *transfer)
 {
-	struct driver_data *drv_data = (struct driver_data *)data;
-	struct spi_controller *master = drv_data->master;
+	struct driver_data *drv_data = spi_controller_get_devdata(master);
 	struct spi_message *message = master->cur_msg;
 	struct chip_data *chip = spi_get_ctldata(message->spi);
 	u32 dma_thresh = chip->dma_threshold;
 	u32 dma_burst = chip->dma_burst_size;
 	u32 change_mask = pxa2xx_spi_get_ssrc1_change_mask(drv_data);
-	struct spi_transfer *transfer;
-	struct spi_transfer *previous;
 	u32 clk_div;
 	u8 bits;
 	u32 speed;
@@ -992,36 +929,6 @@ static void pump_transfers(unsigned long data)
 	int err;
 	int dma_mapped;
 
-	/* Get current state information */
-	transfer = drv_data->cur_transfer;
-
-	/* Handle for abort */
-	if (message->state == ERROR_STATE) {
-		message->status = -EIO;
-		giveback(drv_data);
-		return;
-	}
-
-	/* Handle end of message */
-	if (message->state == DONE_STATE) {
-		message->status = 0;
-		giveback(drv_data);
-		return;
-	}
-
-	/* Delay if requested at end of transfer before CS change */
-	if (message->state == RUNNING_STATE) {
-		previous = list_entry(transfer->transfer_list.prev,
-					struct spi_transfer,
-					transfer_list);
-		if (previous->delay_usecs)
-			udelay(previous->delay_usecs);
-
-		/* Drop chip select only if cs_change is requested */
-		if (previous->cs_change)
-			cs_deassert(drv_data);
-	}
-
 	/* Check if we can DMA this transfer */
 	if (transfer->len > MAX_DMA_LEN && chip->enable_dma) {
 
@@ -1031,30 +938,25 @@ static void pump_transfers(unsigned long data)
 			dev_err(&drv_data->pdev->dev,
 				"Mapped transfer length of %u is greater than %d\n",
 				transfer->len, MAX_DMA_LEN);
-			message->status = -EINVAL;
-			giveback(drv_data);
-			return;
+			return -EINVAL;
 		}
 
 		/* warn ... we force this to PIO mode */
 		dev_warn_ratelimited(&message->spi->dev,
 				     "DMA disabled for transfer length %ld greater than %d\n",
-				     (long)drv_data->len, MAX_DMA_LEN);
+				     (long)transfer->len, MAX_DMA_LEN);
 	}
 
 	/* Setup the transfer state based on the type of transfer */
 	if (pxa2xx_spi_flush(drv_data) == 0) {
 		dev_err(&drv_data->pdev->dev, "Flush failed\n");
-		message->status = -EIO;
-		giveback(drv_data);
-		return;
+		return -EIO;
 	}
 	drv_data->n_bytes = chip->n_bytes;
 	drv_data->tx = (void *)transfer->tx_buf;
 	drv_data->tx_end = drv_data->tx + transfer->len;
 	drv_data->rx = transfer->rx_buf;
 	drv_data->rx_end = drv_data->rx + transfer->len;
-	drv_data->len = transfer->len;
 	drv_data->write = drv_data->tx ? chip->write : null_writer;
 	drv_data->read = drv_data->rx ? chip->read : null_reader;
 
@@ -1096,8 +998,6 @@ static void pump_transfers(unsigned long data)
 					     "DMA burst size reduced to match bits_per_word\n");
 	}
 
-	message->state = RUNNING_STATE;
-
 	dma_mapped = master->can_dma &&
 		     master->can_dma(master, message->spi, transfer) &&
 		     master->cur_msg_mapped;
@@ -1106,12 +1006,9 @@ static void pump_transfers(unsigned long data)
 		/* Ensure we have the correct interrupt handler */
 		drv_data->transfer_handler = pxa2xx_spi_dma_transfer;
 
-		err = pxa2xx_spi_dma_prepare(drv_data);
-		if (err) {
-			message->status = err;
-			giveback(drv_data);
-			return;
-		}
+		err = pxa2xx_spi_dma_prepare(drv_data, transfer);
+		if (err)
+			return err;
 
 		/* Clear status and start DMA engine */
 		cr1 = chip->cr1 | dma_thresh | drv_data->dma_cr1;
@@ -1173,27 +1070,40 @@ static void pump_transfers(unsigned long data)
 			pxa2xx_spi_write(drv_data, SSTO, chip->timeout);
 	}
 
-	cs_assert(drv_data);
-
-	/* after chip select, release the data by enabling service
-	 * requests and interrupts, without changing any mode bits */
+	/*
+	 * Release the data by enabling service requests and interrupts,
+	 * without changing any mode bits
+	 */
 	pxa2xx_spi_write(drv_data, SSCR1, cr1);
+
+	return 1;
 }
 
-static int pxa2xx_spi_transfer_one_message(struct spi_controller *master,
-					   struct spi_message *msg)
+static void pxa2xx_spi_handle_err(struct spi_controller *master,
+				 struct spi_message *msg)
 {
 	struct driver_data *drv_data = spi_controller_get_devdata(master);
 
-	/* Initial message state*/
-	msg->state = START_STATE;
-	drv_data->cur_transfer = list_entry(msg->transfers.next,
-						struct spi_transfer,
-						transfer_list);
+	/* Disable the SSP */
+	pxa2xx_spi_write(drv_data, SSCR0,
+			 pxa2xx_spi_read(drv_data, SSCR0) & ~SSCR0_SSE);
+	/* Clear and disable interrupts and service requests */
+	write_SSSR_CS(drv_data, drv_data->clear_sr);
+	pxa2xx_spi_write(drv_data, SSCR1,
+			 pxa2xx_spi_read(drv_data, SSCR1)
+			 & ~(drv_data->int_cr1 | drv_data->dma_cr1));
+	if (!pxa25x_ssp_comp(drv_data))
+		pxa2xx_spi_write(drv_data, SSTO, 0);
 
-	/* Mark as busy and launch transfers */
-	tasklet_schedule(&drv_data->pump_transfers);
-	return 0;
+	/*
+	 * Stop the DMA if running. Note DMA callback handler may have unset
+	 * the dma_running already, which is fine as stopping is not needed
+	 * then but we shouldn't rely this flag for anything else than
+	 * stopping. For instance to differentiate between PIO and DMA
+	 * transfers.
+	 */
+	if (atomic_read(&drv_data->dma_running))
+		pxa2xx_spi_dma_stop(drv_data);
 }
 
 static int pxa2xx_spi_unprepare_transfer(struct spi_controller *master)
@@ -1649,7 +1559,9 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
 	master->dma_alignment = DMA_ALIGNMENT;
 	master->cleanup = cleanup;
 	master->setup = setup;
-	master->transfer_one_message = pxa2xx_spi_transfer_one_message;
+	master->set_cs = pxa2xx_spi_set_cs;
+	master->transfer_one = pxa2xx_spi_transfer_one;
+	master->handle_err = pxa2xx_spi_handle_err;
 	master->unprepare_transfer_hardware = pxa2xx_spi_unprepare_transfer;
 	master->fw_translate_cs = pxa2xx_spi_fw_translate_cs;
 	master->auto_runtime_pm = true;
@@ -1785,9 +1697,6 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
 		}
 	}
 
-	tasklet_init(&drv_data->pump_transfers, pump_transfers,
-		     (unsigned long)drv_data);
-
 	pm_runtime_set_autosuspend_delay(&pdev->dev, 50);
 	pm_runtime_use_autosuspend(&pdev->dev);
 	pm_runtime_set_active(&pdev->dev);

drivers/spi/spi-pxa2xx.h

@@ -46,15 +46,10 @@ struct driver_data {
 	u32 clear_sr;
 	u32 mask_sr;
 
-	/* Message Transfer pump */
-	struct tasklet_struct pump_transfers;
-
 	/* DMA engine support */
 	atomic_t dma_running;
 
-	/* Current message transfer state info */
-	struct spi_transfer *cur_transfer;
-	size_t len;
+	/* Current transfer state info */
 	void *tx;
 	void *tx_end;
 	void *rx;
@@ -104,11 +99,6 @@ static  inline void pxa2xx_spi_write(const struct driver_data *drv_data,
 	__raw_writel(val, drv_data->ioaddr + reg);
 }
 
-#define START_STATE ((void *)0)
-#define RUNNING_STATE ((void *)1)
-#define DONE_STATE ((void *)2)
-#define ERROR_STATE ((void *)-1)
-
 #define DMA_ALIGNMENT		8
 
 static inline int pxa25x_ssp_comp(struct driver_data *drv_data)
@@ -133,14 +123,15 @@ static inline void write_SSSR_CS(struct driver_data *drv_data, u32 val)
 }
 
 extern int pxa2xx_spi_flush(struct driver_data *drv_data);
-extern void *pxa2xx_spi_next_transfer(struct driver_data *drv_data);
 
 #define MAX_DMA_LEN		SZ_64K
 #define DEFAULT_DMA_CR1		(SSCR1_TSRE | SSCR1_RSRE | SSCR1_TRAIL)
 
 extern irqreturn_t pxa2xx_spi_dma_transfer(struct driver_data *drv_data);
-extern int pxa2xx_spi_dma_prepare(struct driver_data *drv_data);
+extern int pxa2xx_spi_dma_prepare(struct driver_data *drv_data,
+				  struct spi_transfer *xfer);
 extern void pxa2xx_spi_dma_start(struct driver_data *drv_data);
+extern void pxa2xx_spi_dma_stop(struct driver_data *drv_data);
 extern int pxa2xx_spi_dma_setup(struct driver_data *drv_data);
 extern void pxa2xx_spi_dma_release(struct driver_data *drv_data);
 extern int pxa2xx_spi_set_dma_burst_and_threshold(struct chip_data *chip,