spi/pl022: initialize burstsize from FIFO trigger level

Configure the DMA burstsize from the FIFO trigger level supplied
with the controller configuration data. This is based on a patch
from Virupax, but I rewrote it differently.

Reported-by: Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

drivers/spi/spi-pl022.c

@@ -381,6 +381,8 @@ struct pl022 {
 	enum ssp_reading		read;
 	enum ssp_writing		write;
 	u32				exp_fifo_level;
+	enum ssp_rx_level_trig		rx_lev_trig;
+	enum ssp_tx_level_trig		tx_lev_trig;
 	/* DMA settings */
 #ifdef CONFIG_DMA_ENGINE
 	struct dma_chan			*dma_rx_channel;
@@ -907,12 +909,10 @@ static int configure_dma(struct pl022 *pl022)
 	struct dma_slave_config rx_conf = {
 		.src_addr = SSP_DR(pl022->phybase),
 		.direction = DMA_FROM_DEVICE,
-		.src_maxburst = pl022->vendor->fifodepth >> 1,
 	};
 	struct dma_slave_config tx_conf = {
 		.dst_addr = SSP_DR(pl022->phybase),
 		.direction = DMA_TO_DEVICE,
-		.dst_maxburst = pl022->vendor->fifodepth >> 1,
 	};
 	unsigned int pages;
 	int ret;
@@ -926,6 +926,54 @@ static int configure_dma(struct pl022 *pl022)
 	if (!rxchan || !txchan)
 		return -ENODEV;
 
+	/*
+	 * If supplied, the DMA burstsize should equal the FIFO trigger level.
+	 * Notice that the DMA engine uses one-to-one mapping. Since we can
+	 * not trigger on 2 elements this needs explicit mapping rather than
+	 * calculation.
+	 */
+	switch (pl022->rx_lev_trig) {
+	case SSP_RX_1_OR_MORE_ELEM:
+		rx_conf.src_maxburst = 1;
+		break;
+	case SSP_RX_4_OR_MORE_ELEM:
+		rx_conf.src_maxburst = 4;
+		break;
+	case SSP_RX_8_OR_MORE_ELEM:
+		rx_conf.src_maxburst = 8;
+		break;
+	case SSP_RX_16_OR_MORE_ELEM:
+		rx_conf.src_maxburst = 16;
+		break;
+	case SSP_RX_32_OR_MORE_ELEM:
+		rx_conf.src_maxburst = 32;
+		break;
+	default:
+		rx_conf.src_maxburst = pl022->vendor->fifodepth >> 1;
+		break;
+	}
+
+	switch (pl022->tx_lev_trig) {
+	case SSP_TX_1_OR_MORE_EMPTY_LOC:
+		tx_conf.dst_maxburst = 1;
+		break;
+	case SSP_TX_4_OR_MORE_EMPTY_LOC:
+		tx_conf.dst_maxburst = 4;
+		break;
+	case SSP_TX_8_OR_MORE_EMPTY_LOC:
+		tx_conf.dst_maxburst = 8;
+		break;
+	case SSP_TX_16_OR_MORE_EMPTY_LOC:
+		tx_conf.dst_maxburst = 16;
+		break;
+	case SSP_TX_32_OR_MORE_EMPTY_LOC:
+		tx_conf.dst_maxburst = 32;
+		break;
+	default:
+		tx_conf.dst_maxburst = pl022->vendor->fifodepth >> 1;
+		break;
+	}
+
 	switch (pl022->read) {
 	case READING_NULL:
 		/* Use the same as for writing */
@@ -1871,6 +1919,9 @@ static int pl022_setup(struct spi_device *spi)
 		goto err_config_params;
 	}
 
+	pl022->rx_lev_trig = chip_info->rx_lev_trig;
+	pl022->tx_lev_trig = chip_info->tx_lev_trig;
+
 	/* Now set controller state based on controller data */
 	chip->xfer_type = chip_info->com_mode;
 	if (!chip_info->cs_control) {