serial: tegra: add support to use 8 bytes trigger

Add support to use 8 bytes trigger for Tegra186 SOC.

Signed-off-by: Shardar Shariff Md <smohammed@nvidia.com>
Signed-off-by: Krishna Yarlagadda <kyarlagadda@nvidia.com>
Link: https://lore.kernel.org/r/1567572187-29820-9-git-send-email-kyarlagadda@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/serial-tegra.c

@@ -88,6 +88,7 @@ struct tegra_uart_chip_data {
 	bool	support_clk_src_div;
 	bool	fifo_mode_enable_status;
 	int	uart_max_port;
+	int	max_dma_burst_bytes;
 };
 
 struct tegra_uart_port {
@@ -931,7 +932,12 @@ static int tegra_uart_hw_init(struct tegra_uart_port *tup)
 	 * programmed in the DMA registers.
 	 */
 	tup->fcr_shadow = UART_FCR_ENABLE_FIFO;
-	tup->fcr_shadow |= UART_FCR_R_TRIG_01;
+
+	if (tup->cdata->max_dma_burst_bytes == 8)
+		tup->fcr_shadow |= UART_FCR_R_TRIG_10;
+	else
+		tup->fcr_shadow |= UART_FCR_R_TRIG_01;
+
 	tup->fcr_shadow |= TEGRA_UART_TX_TRIG_16B;
 	tegra_uart_write(tup, tup->fcr_shadow, UART_FCR);
 
@@ -1045,7 +1051,7 @@ static int tegra_uart_dma_channel_allocate(struct tegra_uart_port *tup,
 		}
 		dma_sconfig.src_addr = tup->uport.mapbase;
 		dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
-		dma_sconfig.src_maxburst = 4;
+		dma_sconfig.src_maxburst = tup->cdata->max_dma_burst_bytes;
 		tup->rx_dma_chan = dma_chan;
 		tup->rx_dma_buf_virt = dma_buf;
 		tup->rx_dma_buf_phys = dma_phys;
@@ -1324,6 +1330,7 @@ static struct tegra_uart_chip_data tegra20_uart_chip_data = {
 	.support_clk_src_div		= false,
 	.fifo_mode_enable_status	= false,
 	.uart_max_port			= 5,
+	.max_dma_burst_bytes		= 4,
 };
 
 static struct tegra_uart_chip_data tegra30_uart_chip_data = {
@@ -1332,6 +1339,7 @@ static struct tegra_uart_chip_data tegra30_uart_chip_data = {
 	.support_clk_src_div		= true,
 	.fifo_mode_enable_status	= false,
 	.uart_max_port			= 5,
+	.max_dma_burst_bytes		= 4,
 };
 
 static struct tegra_uart_chip_data tegra186_uart_chip_data = {
@@ -1340,6 +1348,7 @@ static struct tegra_uart_chip_data tegra186_uart_chip_data = {
 	.support_clk_src_div		= true,
 	.fifo_mode_enable_status	= true,
 	.uart_max_port			= 8,
+	.max_dma_burst_bytes		= 8,
 };
 
 static const struct of_device_id tegra_uart_of_match[] = {