[PATCH 3/4] serial: 8250-mtk: add uart DMA support

Long Cheng
2017-02-16T11:07:30Z

Modify uart register to support DMA function.

Signed-off-by: Long Cheng <long.cheng@mediatek.com>
---
drivers/tty/serial/8250/8250_mtk.c | 194 +++++++++++++++++++++++++++++++++++-
1 file changed, 193 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
index ce0cc47..7d7a864 100644
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -23,6 +23,10 @@
#include <linux/pm_runtime.h>
#include <linux/serial_8250.h>
#include <linux/serial_reg.h>
+#include <linux/console.h>
+#include <linux/dma-mapping.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>

#include "8250.h"

@@ -30,13 +34,165 @@
#define UART_MTK_SAMPLE_COUNT 0x0a /* Sample count register */
#define UART_MTK_SAMPLE_POINT 0x0b /* Sample point register */
#define MTK_UART_RATE_FIX 0x0d /* UART Rate Fix Register */
-
+#define UART_MTK_DMA_EN 0x13
+#define TX_TRIGGER 1
+#define RX_TRIGGER 8192
+
+#ifdef CONFIG_SERIAL_8250_DMA
+enum dma_rx_status {
+ DMA_RX_START = 0,
+ DMA_RX_RUNNING = 1,
+ DMA_RX_SHUTDOWN = 2,
+};
+#endif
struct mtk8250_data {
int line;
+ int rxpos;
struct clk *uart_clk;
struct clk *bus_clk;
+ struct uart_8250_dma *dma;
+#ifdef CONFIG_SERIAL_8250_DMA
+ enum dma_rx_status rxstatus;
+#endif
};

+#ifdef CONFIG_SERIAL_8250_DMA
+static int mtk8250_rx_dma(struct uart_8250_port *up);
+
+static void __mtkdma_rx_complete(void *param)
+{
+ struct uart_8250_port *up = param;
+ struct uart_8250_dma *dma = up->dma;
+ struct mtk8250_data *data = up->port.private_data;
+ struct tty_port *tty_port = &up->port.state->port;
+ struct dma_tx_state state;
+ unsigned char *ptr;
+ int copied;
+
+ dma_sync_single_for_cpu(dma->rxchan->device->dev, dma->rx_addr,
+ dma->rx_size, DMA_FROM_DEVICE);
+
+ dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
+ dmaengine_terminate_all(dma->rxchan);
+
+ if (data->rxstatus == DMA_RX_SHUTDOWN)
+ return;
+
+ if ((data->rxpos + state.residue) <= dma->rx_size) {
+ ptr = (unsigned char *)(data->rxpos + dma->rx_buf);
+ copied = tty_insert_flip_string(tty_port, ptr, state.residue);
+ } else {
+ ptr = (unsigned char *)(data->rxpos + dma->rx_buf);
+ copied = tty_insert_flip_string(tty_port, ptr,
+ (dma->rx_size - data->rxpos));
+ ptr = (unsigned char *)(dma->rx_buf);
+ copied += tty_insert_flip_string(tty_port, ptr,
+ (data->rxpos + state.residue - dma->rx_size));
+ }
+ up->port.icount.rx += copied;
+
+ tty_flip_buffer_push(tty_port);
+
+ mtk8250_rx_dma(up);
+}
+
+static int mtk8250_rx_dma(struct uart_8250_port *up)
+{
+ struct uart_8250_dma *dma = up->dma;
+ struct mtk8250_data *data = up->port.private_data;
+ struct dma_async_tx_descriptor *desc;
+ struct dma_tx_state state;
+
+ desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr,
+ dma->rx_size, DMA_DEV_TO_MEM,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ if (!desc)
+ return -EBUSY;
+
+ desc->callback = __mtkdma_rx_complete;
+ desc->callback_param = up;
+
+ dma->rx_cookie = dmaengine_submit(desc);
+
+ dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
+ data->rxpos = state.residue;
+
+ dma_sync_single_for_device(dma->rxchan->device->dev, dma->rx_addr,
+ dma->rx_size, DMA_FROM_DEVICE);
+
+ dma_async_issue_pending(dma->rxchan);
+
+ return 0;
+}
+
+static void mtk_dma_enable(struct uart_8250_port *up)
+{
+ struct uart_port *port = &up->port;
+ struct uart_8250_dma *dma = up->dma;
+ struct mtk8250_data *data = up->port.private_data;
+ int tmp = 0;
+
+ if (data->rxstatus != DMA_RX_START)
+ return;
+
+ dma->rxconf.direction = DMA_DEV_TO_MEM;
+ dma->rxconf.src_addr_width = dma->rx_size/1024;
+ dma->rxconf.src_addr = dma->rx_addr;
+
+ dma->txconf.direction = DMA_MEM_TO_DEV;
+ dma->txconf.dst_addr_width = UART_XMIT_SIZE/1024;
+ dma->txconf.dst_addr = dma->tx_addr;
+
+ serial_port_out(port, UART_FCR, ((1 << 0)|(1 << 1)|(1 << 2)));
+ serial_port_out(port, UART_MTK_DMA_EN,
+ (serial_port_in(port, UART_MTK_DMA_EN) |
+ ((1 << 0) | (1 << 2))));
+ serial_port_out(port, UART_MTK_DMA_EN,
+ (serial_port_in(port, UART_MTK_DMA_EN) |
+ (1 << 1)));
+
+ tmp = serial_port_in(port, UART_LCR);
+ serial_port_out(port, UART_LCR, UART_LCR_CONF_MODE_B);
+ serial_port_out(port, UART_EFR, UART_EFR_ECB);
+ serial_port_out(port, UART_LCR, tmp);
+
+ dmaengine_slave_config(dma->rxchan, &dma->rxconf);
+ dmaengine_slave_config(dma->txchan, &dma->txconf);
+
+ data->rxstatus = DMA_RX_RUNNING;
+ data->rxpos = 0;
+ mtk8250_rx_dma(up);
+}
+#endif
+
+static int mtk8250_startup(struct uart_port *port)
+{
+#ifdef CONFIG_SERIAL_8250_DMA
+ struct uart_8250_port *up =
+ container_of(port, struct uart_8250_port, port);
+ struct mtk8250_data *data = port->private_data;
+
+ if (up->dma != NULL)
+ data->rxstatus = DMA_RX_START;
+#endif
+
+ return serial8250_do_startup(port);
+}
+
+static void mtk8250_shutdown(struct uart_port *port)
+{
+#ifdef CONFIG_SERIAL_8250_DMA
+ struct uart_8250_port *up =
+ container_of(port, struct uart_8250_port, port);
+ struct mtk8250_data *data = port->private_data;
+
+ if (up->dma != NULL)
+ data->rxstatus = DMA_RX_SHUTDOWN;
+#endif
+
+ return serial8250_do_shutdown(port);
+}
+
static void
mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
struct ktermios *old)
@@ -44,6 +200,10 @@ struct mtk8250_data {
struct uart_8250_port *up = up_to_u8250p(port);
unsigned long flags;
unsigned int baud, quot;
+#ifdef CONFIG_SERIAL_8250_DMA
+ if (up->dma != NULL)
+ mtk_dma_enable(up);
+#endif

serial8250_do_set_termios(port, termios, old);

@@ -152,9 +312,20 @@ static int __maybe_unused mtk8250_runtime_resume(struct device *dev)
pm_runtime_put_sync_suspend(port->dev);
}

+#ifdef CONFIG_SERIAL_8250_DMA
+static bool the_no_dma_filter_fn(struct dma_chan *chan, void *param)
+{
+ return false;
+}
+#endif
+
static int mtk8250_probe_of(struct platform_device *pdev, struct uart_port *p,
struct mtk8250_data *data)
{
+#ifdef CONFIG_SERIAL_8250_DMA
+ int dmacnt;
+#endif
+
data->uart_clk = devm_clk_get(&pdev->dev, "baud");
if (IS_ERR(data->uart_clk)) {
/*
@@ -174,6 +345,21 @@ static int mtk8250_probe_of(struct platform_device *pdev, struct uart_port *p,
if (IS_ERR(data->bus_clk))
return PTR_ERR(data->bus_clk);

+ data->dma = NULL;
+#ifdef CONFIG_SERIAL_8250_DMA
+ dmacnt = of_property_count_strings(pdev->dev.of_node, "dma-names");
+ if (dmacnt == 2) {
+ data->dma = devm_kzalloc(&pdev->dev,
+ sizeof(*(data->dma)),
+ GFP_KERNEL);
+ data->dma->fn = the_no_dma_filter_fn;
+ data->dma->rx_size = RX_TRIGGER;
+ data->dma->rxconf.src_maxburst = RX_TRIGGER;
+ data->dma->txconf.dst_maxburst = TX_TRIGGER;
+ data->dma->rx_dma = mtk8250_rx_dma;
+ }
+#endif
+
return 0;
}

@@ -216,8 +402,14 @@ static int mtk8250_probe(struct platform_device *pdev)
uart.port.iotype = UPIO_MEM32;
uart.port.regshift = 2;
uart.port.private_data = data;
+ uart.port.shutdown = mtk8250_shutdown;
+ uart.port.startup = mtk8250_startup;
uart.port.set_termios = mtk8250_set_termios;
uart.port.uartclk = clk_get_rate(data->uart_clk);
+#ifdef CONFIG_SERIAL_8250_DMA
+ if (data->dma)
+ uart.dma = data->dma;
+#endif

/* Disable Rate Fix function */
writel(0x0, uart.port.membase +
--
1.7.9.5