[PATCH 0/5] Add new features for the Spreadtrum serial controller

[PATCH 0/5] Add new features for the Spreadtrum serial controller

[Baolin Wang]

This patch set fixes the baud rate calculation formula issue, as well as
adding power management support and DMA mode support for the Spreadtrum
serial controller.

Lanqing Liu (5):
  serial: sprd: Modify the baud rate calculation formula
  dt-bindings: serial: sprd: Add clocks and clocks-names properties
  serial: sprd: Add power management for the Spreadtrum serial
    controller
  dt-bindings: serial: sprd: Add dma properties to support DMA mode
  serial: sprd: Add DMA mode support

 .../devicetree/bindings/serial/sprd-uart.txt       |   17 +-
 drivers/tty/serial/sprd_serial.c                   |  503 +++++++++++++++++++-
 2 files changed, 499 insertions(+), 21 deletions(-)

-- 
1.7.9.5

[PATCH 1/5] serial: sprd: Modify the baud rate calculation formula

[Baolin Wang]

From: Lanqing Liu <lanqing.liu@unisoc.com>

When the source clock is not divisible by the expected baud rate and
the remainder is not less than half of the expected baud rate, the old
formular will round up the frequency division coefficient. This will
make the actual baud rate less than the expected value and can not meet
the external transmission requirements.

Thus this patch modifies the baud rate calculation formula to support
the serial controller output the maximum baud rate.

Signed-off-by: Lanqing Liu <lanqing.liu@unisoc.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
 drivers/tty/serial/sprd_serial.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sprd_serial.c
index 4287ca3..1891a45 100644
--- a/drivers/tty/serial/sprd_serial.c
+++ b/drivers/tty/serial/sprd_serial.c
@@ -371,7 +371,7 @@ static void sprd_set_termios(struct uart_port *port,
 	/* ask the core to calculate the divisor for us */
 	baud = uart_get_baud_rate(port, termios, old, 0, SPRD_BAUD_IO_LIMIT);
 
-	quot = (unsigned int)((port->uartclk + baud / 2) / baud);
+	quot = port->uartclk / baud;
 
 	/* set data length */
 	switch (termios->c_cflag & CSIZE) {
-- 
1.7.9.5

[PATCH 2/5] dt-bindings: serial: sprd: Add clocks and clocks-names properties

[Baolin Wang]

From: Lanqing Liu <lanqing.liu@unisoc.com>

This patch adds clocks and clocks-names properties, which are used to do
power management for our UART driver.

Signed-off-by: Lanqing Liu <lanqing.liu@unisoc.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
 .../devicetree/bindings/serial/sprd-uart.txt       |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/serial/sprd-uart.txt b/Documentation/devicetree/bindings/serial/sprd-uart.txt
index cab40f0..6eb5863 100644
--- a/Documentation/devicetree/bindings/serial/sprd-uart.txt
+++ b/Documentation/devicetree/bindings/serial/sprd-uart.txt
@@ -7,7 +7,13 @@ Required properties:
 
 - reg: offset and length of the register set for the device
 - interrupts: exactly one interrupt specifier
-- clocks: phandles to input clocks.
+- clock-names: Should contain following entries:
+  "enable" for UART module enable clock,
+  "uart" for UART clock,
+  "source" for UART source (parent) clock.
+- clocks: Should contain a clock specifier for each entry in clock-names.
+  UART clock and source clock are optional properties, but enable clock
+  is required.
 
 Example:
 	uart0: serial@0 {
@@ -15,5 +21,6 @@ Example:
 			     "sprd,sc9836-uart";
 		reg = <0x0 0x100>;
 		interrupts = <GIC_SPI 2 IRQ_TYPE_LEVEL_HIGH>;
-		clocks = <&ext_26m>;
+		clock-names = "enable", "uart", "source";
+		clocks = <&clk_ap_apb_gates 9>, <&clk_uart0>, <&ext_26m>;
 	};
-- 
1.7.9.5

[PATCH 3/5] serial: sprd: Add power management for the Spreadtrum serial controller

[Baolin Wang]

From: Lanqing Liu <lanqing.liu@unisoc.com>

This patch adds power management for the Spreadtrum serial controller.

Signed-off-by: Lanqing Liu <lanqing.liu@unisoc.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
 drivers/tty/serial/sprd_serial.c |   61 +++++++++++++++++++++++++++++++++++---
 1 file changed, 57 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sprd_serial.c
index 1891a45..8f45b66 100644
--- a/drivers/tty/serial/sprd_serial.c
+++ b/drivers/tty/serial/sprd_serial.c
@@ -100,10 +100,12 @@
 #define SPRD_IMSR_TX_FIFO_EMPTY	BIT(1)
 #define SPRD_IMSR_BREAK_DETECT	BIT(7)
 #define SPRD_IMSR_TIMEOUT	BIT(13)
+#define SPRD_DEFAULT_SOURCE_CLK	26000000
 
 struct sprd_uart_port {
 	struct uart_port port;
 	char name[16];
+	struct clk *clk;
 };
 
 static struct sprd_uart_port *sprd_port[UART_NR_MAX];
@@ -491,6 +493,22 @@ static int sprd_verify_port(struct uart_port *port, struct serial_struct *ser)
 	return 0;
 }
 
+static void sprd_pm(struct uart_port *port, unsigned int state,
+		unsigned int oldstate)
+{
+	struct sprd_uart_port *sup =
+		container_of(port, struct sprd_uart_port, port);
+
+	switch (state) {
+	case UART_PM_STATE_ON:
+		clk_prepare_enable(sup->clk);
+		break;
+	case UART_PM_STATE_OFF:
+		clk_disable_unprepare(sup->clk);
+		break;
+	}
+}
+
 static const struct uart_ops serial_sprd_ops = {
 	.tx_empty = sprd_tx_empty,
 	.get_mctrl = sprd_get_mctrl,
@@ -507,6 +525,7 @@ static int sprd_verify_port(struct uart_port *port, struct serial_struct *ser)
 	.request_port = sprd_request_port,
 	.config_port = sprd_config_port,
 	.verify_port = sprd_verify_port,
+	.pm = sprd_pm,
 };
 
 #ifdef CONFIG_SERIAL_SPRD_CONSOLE
@@ -671,11 +690,45 @@ static int sprd_remove(struct platform_device *dev)
 	return 0;
 }
 
+static int sprd_clk_init(struct uart_port *uport)
+{
+	struct clk *clk_uart, *clk_parent;
+	struct sprd_uart_port *u = sprd_port[uport->line];
+
+	clk_uart = devm_clk_get(uport->dev, "uart");
+	if (IS_ERR(clk_uart)) {
+		dev_warn(uport->dev, "uart%d can't get uart clock\n",
+			 uport->line);
+		clk_uart = NULL;
+	}
+
+	clk_parent = devm_clk_get(uport->dev, "source");
+	if (IS_ERR(clk_parent)) {
+		dev_warn(uport->dev, "uart%d can't get source clock\n",
+			 uport->line);
+		clk_parent = NULL;
+	}
+
+	if (!clk_uart || clk_set_parent(clk_uart, clk_parent))
+		uport->uartclk = SPRD_DEFAULT_SOURCE_CLK;
+	else
+		uport->uartclk = clk_get_rate(clk_uart);
+
+	u->clk = devm_clk_get(uport->dev, "enable");
+	if (IS_ERR(u->clk)) {
+		if (PTR_ERR(u->clk) != -EPROBE_DEFER)
+			dev_err(uport->dev, "uart%d can't get enable clock\n",
+				uport->line);
+		return PTR_ERR(u->clk);
+	}
+
+	return 0;
+}
+
 static int sprd_probe(struct platform_device *pdev)
 {
 	struct resource *res;
 	struct uart_port *up;
-	struct clk *clk;
 	int irq;
 	int index;
 	int ret;
@@ -704,9 +757,9 @@ static int sprd_probe(struct platform_device *pdev)
 	up->ops = &serial_sprd_ops;
 	up->flags = UPF_BOOT_AUTOCONF;
 
-	clk = devm_clk_get(&pdev->dev, NULL);
-	if (!IS_ERR_OR_NULL(clk))
-		up->uartclk = clk_get_rate(clk);
+	ret = sprd_clk_init(up);
+	if (ret)
+		return ret;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	up->membase = devm_ioremap_resource(&pdev->dev, res);
-- 
1.7.9.5

[PATCH 4/5] dt-bindings: serial: sprd: Add dma properties to support DMA mode

[Baolin Wang]

From: Lanqing Liu <lanqing.liu@unisoc.com>

This patch adds dmas and dma-names properties for the UART DMA mode.

Signed-off-by: Lanqing Liu <lanqing.liu@unisoc.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
 .../devicetree/bindings/serial/sprd-uart.txt       |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/serial/sprd-uart.txt b/Documentation/devicetree/bindings/serial/sprd-uart.txt
index 6eb5863..9ac28f6 100644
--- a/Documentation/devicetree/bindings/serial/sprd-uart.txt
+++ b/Documentation/devicetree/bindings/serial/sprd-uart.txt
@@ -15,12 +15,18 @@ Required properties:
   UART clock and source clock are optional properties, but enable clock
   is required.
 
+Optional properties:
+- dma-names: Should contain "tx" for transmit and "rx" for receive channels.
+- dmas: A list of dma specifiers, one for each entry in dma-names.
+
 Example:
 	uart0: serial@0 {
 		compatible = "sprd,sc9860-uart",
 			     "sprd,sc9836-uart";
 		reg = <0x0 0x100>;
 		interrupts = <GIC_SPI 2 IRQ_TYPE_LEVEL_HIGH>;
+		dma-names = "rx", "tx";
+		dmas = <&ap_dma 19 19>, <&ap_dma 20 20>;
 		clock-names = "enable", "uart", "source";
 		clocks = <&clk_ap_apb_gates 9>, <&clk_uart0>, <&ext_26m>;
 	};
-- 
1.7.9.5

[PATCH 5/5] serial: sprd: Add DMA mode support

[Baolin Wang]

From: Lanqing Liu <lanqing.liu@unisoc.com>

Add DMA mode support for the Spreadtrum serial controller.

Signed-off-by: Lanqing Liu <lanqing.liu@unisoc.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
 drivers/tty/serial/sprd_serial.c |  440 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 426 insertions(+), 14 deletions(-)

diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sprd_serial.c
index 8f45b66..6aebd77 100644
--- a/drivers/tty/serial/sprd_serial.c
+++ b/drivers/tty/serial/sprd_serial.c
@@ -10,6 +10,9 @@
 #include <linux/clk.h>
 #include <linux/console.h>
 #include <linux/delay.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/dma/sprd-dma.h>
 #include <linux/io.h>
 #include <linux/ioport.h>
 #include <linux/kernel.h>
@@ -75,6 +78,7 @@
 
 /* control register 1 */
 #define SPRD_CTL1		0x001C
+#define SPRD_DMA_EN		BIT(15)
 #define RX_HW_FLOW_CTL_THLD	BIT(6)
 #define RX_HW_FLOW_CTL_EN	BIT(7)
 #define TX_HW_FLOW_CTL_EN	BIT(8)
@@ -86,6 +90,7 @@
 #define THLD_TX_EMPTY		0x40
 #define THLD_TX_EMPTY_SHIFT	8
 #define THLD_RX_FULL		0x40
+#define THLD_RX_FULL_MASK	GENMASK(6, 0)
 
 /* config baud rate register */
 #define SPRD_CLKD0		0x0024
@@ -102,15 +107,36 @@
 #define SPRD_IMSR_TIMEOUT	BIT(13)
 #define SPRD_DEFAULT_SOURCE_CLK	26000000
 
+#define SPRD_RX_DMA_STEP	1
+#define SPRD_RX_FIFO_FULL	1
+#define SPRD_TX_FIFO_FULL	0x20
+#define SPRD_UART_RX_SIZE	(UART_XMIT_SIZE / 4)
+
+struct sprd_uart_dma {
+	struct dma_chan *chn;
+	unsigned char *virt;
+	dma_addr_t phys_addr;
+	dma_cookie_t cookie;
+	u32 trans_len;
+	bool enable;
+};
+
 struct sprd_uart_port {
 	struct uart_port port;
 	char name[16];
 	struct clk *clk;
+	struct sprd_uart_dma tx_dma;
+	struct sprd_uart_dma rx_dma;
+	dma_addr_t pos;
+	unsigned char *rx_buf_tail;
 };
 
 static struct sprd_uart_port *sprd_port[UART_NR_MAX];
 static int sprd_ports_num;
 
+static int sprd_start_dma_rx(struct uart_port *port);
+static int sprd_tx_dma_config(struct uart_port *port);
+
 static inline unsigned int serial_in(struct uart_port *port,
 				     unsigned int offset)
 {
@@ -141,45 +167,389 @@ static void sprd_set_mctrl(struct uart_port *port, unsigned int mctrl)
 	/* nothing to do */
 }
 
-static void sprd_stop_tx(struct uart_port *port)
+static void sprd_stop_rx(struct uart_port *port)
 {
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
 	unsigned int ien, iclr;
 
+	if (sp->rx_dma.enable)
+		dmaengine_terminate_all(sp->rx_dma.chn);
+
 	iclr = serial_in(port, SPRD_ICLR);
 	ien = serial_in(port, SPRD_IEN);
 
-	iclr |= SPRD_IEN_TX_EMPTY;
-	ien &= ~SPRD_IEN_TX_EMPTY;
+	ien &= ~(SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT);
+	iclr |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT;
 
-	serial_out(port, SPRD_ICLR, iclr);
 	serial_out(port, SPRD_IEN, ien);
+	serial_out(port, SPRD_ICLR, iclr);
 }
 
-static void sprd_start_tx(struct uart_port *port)
+static void sprd_uart_dma_enable(struct uart_port *port, bool enable)
 {
-	unsigned int ien;
+	u32 val = serial_in(port, SPRD_CTL1);
 
-	ien = serial_in(port, SPRD_IEN);
-	if (!(ien & SPRD_IEN_TX_EMPTY)) {
-		ien |= SPRD_IEN_TX_EMPTY;
-		serial_out(port, SPRD_IEN, ien);
+	if (enable)
+		val |= SPRD_DMA_EN;
+	else
+		val &= ~SPRD_DMA_EN;
+
+	serial_out(port, SPRD_CTL1, val);
+}
+
+static void sprd_stop_tx_dma(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct circ_buf *xmit = &port->state->xmit;
+	struct dma_tx_state state;
+	u32 trans_len;
+
+	dmaengine_pause(sp->tx_dma.chn);
+
+	dmaengine_tx_status(sp->tx_dma.chn, sp->tx_dma.cookie, &state);
+	if (state.residue) {
+		trans_len = state.residue - sp->tx_dma.phys_addr;
+		xmit->tail = (xmit->tail + trans_len) & (UART_XMIT_SIZE - 1);
+		port->icount.tx += trans_len;
+		dma_unmap_single(port->dev, sp->tx_dma.phys_addr,
+				 sp->tx_dma.trans_len, DMA_TO_DEVICE);
 	}
+
+	dmaengine_terminate_all(sp->tx_dma.chn);
+	sp->tx_dma.trans_len = 0;
 }
 
-static void sprd_stop_rx(struct uart_port *port)
+static int sprd_tx_buf_remap(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct circ_buf *xmit = &port->state->xmit;
+
+	sp->tx_dma.trans_len =
+		CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+
+	sp->tx_dma.phys_addr = dma_map_single(port->dev,
+					      (void *)&(xmit->buf[xmit->tail]),
+					      sp->tx_dma.trans_len,
+					      DMA_TO_DEVICE);
+	return dma_mapping_error(port->dev, sp->tx_dma.phys_addr);
+}
+
+static void sprd_complete_tx_dma(void *data)
+{
+	struct uart_port *port = (struct uart_port *)data;
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct circ_buf *xmit = &port->state->xmit;
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+	dma_unmap_single(port->dev, sp->tx_dma.phys_addr,
+			 sp->tx_dma.trans_len, DMA_TO_DEVICE);
+
+	xmit->tail = (xmit->tail + sp->tx_dma.trans_len) & (UART_XMIT_SIZE - 1);
+	port->icount.tx += sp->tx_dma.trans_len;
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+
+	if (uart_circ_empty(xmit) || sprd_tx_buf_remap(port) ||
+	    sprd_tx_dma_config(port))
+		sp->tx_dma.trans_len = 0;
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static int sprd_uart_dma_submit(struct uart_port *port,
+				struct sprd_uart_dma *ud, u32 trans_len,
+				enum dma_transfer_direction direction,
+				dma_async_tx_callback callback)
 {
+	struct dma_async_tx_descriptor *dma_des;
+	unsigned long flags;
+
+	flags = SPRD_DMA_FLAGS(SPRD_DMA_CHN_MODE_NONE,
+			       SPRD_DMA_NO_TRG,
+			       SPRD_DMA_FRAG_REQ,
+			       SPRD_DMA_TRANS_INT);
+
+	dma_des = dmaengine_prep_slave_single(ud->chn, ud->phys_addr, trans_len,
+					      direction, flags);
+	if (!dma_des)
+		return -ENODEV;
+
+	dma_des->callback = callback;
+	dma_des->callback_param = port;
+
+	ud->cookie = dmaengine_submit(dma_des);
+	if (dma_submit_error(ud->cookie))
+		return dma_submit_error(ud->cookie);
+
+	dma_async_issue_pending(ud->chn);
+
+	return 0;
+}
+
+static int sprd_tx_dma_config(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	u32 burst = sp->tx_dma.trans_len > SPRD_TX_FIFO_FULL ?
+		SPRD_TX_FIFO_FULL : sp->tx_dma.trans_len;
+	int ret;
+	struct dma_slave_config cfg = {
+		.dst_addr = port->mapbase + SPRD_TXD,
+		.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
+		.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
+		.src_maxburst = burst,
+	};
+
+	ret = dmaengine_slave_config(sp->tx_dma.chn, &cfg);
+	if (ret < 0)
+		return ret;
+
+	return sprd_uart_dma_submit(port, &sp->tx_dma, sp->tx_dma.trans_len,
+				    DMA_MEM_TO_DEV, sprd_complete_tx_dma);
+}
+
+static void sprd_start_tx_dma(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct circ_buf *xmit = &port->state->xmit;
+
+	if (port->x_char) {
+		serial_out(port, SPRD_TXD, port->x_char);
+		port->icount.tx++;
+		port->x_char = 0;
+		return;
+	}
+
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+		sprd_stop_tx_dma(port);
+		return;
+	}
+
+	if (sp->tx_dma.trans_len)
+		return;
+
+	if (sprd_tx_buf_remap(port) || sprd_tx_dma_config(port))
+		sp->tx_dma.trans_len = 0;
+}
+
+static void sprd_rx_full_thld(struct uart_port *port, u32 thld)
+{
+	u32 val = serial_in(port, SPRD_CTL2);
+
+	val &= ~THLD_RX_FULL_MASK;
+	val |= thld & THLD_RX_FULL_MASK;
+	serial_out(port, SPRD_CTL2, val);
+}
+
+static int sprd_rx_alloc_buf(struct sprd_uart_port *sp)
+{
+	sp->rx_dma.virt = dma_alloc_coherent(sp->port.dev, SPRD_UART_RX_SIZE,
+					     &sp->rx_dma.phys_addr, GFP_KERNEL);
+	if (!sp->rx_dma.virt)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void sprd_rx_free_buf(struct sprd_uart_port *sp)
+{
+	if (sp->rx_dma.virt)
+		dma_free_coherent(sp->port.dev, SPRD_UART_RX_SIZE,
+				  sp->rx_dma.virt, sp->rx_dma.phys_addr);
+
+}
+
+static int sprd_rx_dma_config(struct uart_port *port, u32 burst)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct dma_slave_config cfg = {
+		.src_addr = port->mapbase + SPRD_RXD,
+		.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
+		.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
+		.src_maxburst = burst,
+	};
+
+	return dmaengine_slave_config(sp->rx_dma.chn, &cfg);
+}
+
+static void sprd_uart_dma_rx(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct tty_port *tty = &port->state->port;
+
+	port->icount.rx += sp->rx_dma.trans_len;
+	tty_insert_flip_string(tty, sp->rx_buf_tail, sp->rx_dma.trans_len);
+	tty_flip_buffer_push(tty);
+}
+
+static void sprd_uart_dma_irq(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct dma_tx_state state;
+	enum dma_status status;
+
+	status = dmaengine_tx_status(sp->rx_dma.chn,
+				     sp->rx_dma.cookie, &state);
+	if (status == DMA_ERROR)
+		sprd_stop_rx(port);
+
+	if (!state.residue && sp->pos == sp->rx_dma.phys_addr)
+		return;
+
+	if (!state.residue) {
+		sp->rx_dma.trans_len = SPRD_UART_RX_SIZE +
+			sp->rx_dma.phys_addr - sp->pos;
+		sp->pos = sp->rx_dma.phys_addr;
+	} else {
+		sp->rx_dma.trans_len = state.residue - sp->pos;
+		sp->pos = state.residue;
+	}
+
+	sprd_uart_dma_rx(port);
+	sp->rx_buf_tail += sp->rx_dma.trans_len;
+}
+
+static void sprd_complete_rx_dma(void *data)
+{
+	struct uart_port *port = (struct uart_port *)data;
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct dma_tx_state state;
+	enum dma_status status;
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	status = dmaengine_tx_status(sp->rx_dma.chn,
+				     sp->rx_dma.cookie, &state);
+	if (status != DMA_COMPLETE) {
+		sprd_stop_rx(port);
+		spin_unlock_irqrestore(&port->lock, flags);
+		return;
+	}
+
+	if (sp->pos != sp->rx_dma.phys_addr) {
+		sp->rx_dma.trans_len =  SPRD_UART_RX_SIZE +
+			sp->rx_dma.phys_addr - sp->pos;
+		sprd_uart_dma_rx(port);
+		sp->rx_buf_tail += sp->rx_dma.trans_len;
+	}
+
+	if (sprd_start_dma_rx(port))
+		sprd_stop_rx(port);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static int sprd_start_dma_rx(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	int ret;
+
+	if (!sp->rx_dma.enable)
+		return 0;
+
+	sp->pos = sp->rx_dma.phys_addr;
+	sp->rx_buf_tail = sp->rx_dma.virt;
+	sprd_rx_full_thld(port, SPRD_RX_FIFO_FULL);
+	ret = sprd_rx_dma_config(port, SPRD_RX_DMA_STEP);
+	if (ret)
+		return ret;
+
+	return sprd_uart_dma_submit(port, &sp->rx_dma, SPRD_UART_RX_SIZE,
+				    DMA_DEV_TO_MEM, sprd_complete_rx_dma);
+}
+
+static void sprd_release_dma(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+
+	sprd_uart_dma_enable(port, false);
+
+	if (sp->rx_dma.enable)
+		dma_release_channel(sp->rx_dma.chn);
+
+	if (sp->tx_dma.enable)
+		dma_release_channel(sp->tx_dma.chn);
+
+	sp->tx_dma.enable = false;
+	sp->rx_dma.enable = false;
+}
+
+static void sprd_request_dma(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+
+	sp->tx_dma.enable = true;
+	sp->rx_dma.enable = true;
+
+	sp->tx_dma.chn = dma_request_chan(port->dev, "tx");
+	if (IS_ERR(sp->tx_dma.chn)) {
+		dev_err(port->dev, "request TX DMA channel failed, ret = %ld\n",
+			PTR_ERR(sp->tx_dma.chn));
+		sp->tx_dma.enable = false;
+	}
+
+	sp->rx_dma.chn = dma_request_chan(port->dev, "rx");
+	if (IS_ERR(sp->rx_dma.chn)) {
+		dev_err(port->dev, "request RX DMA channel failed, ret = %ld\n",
+			PTR_ERR(sp->tx_dma.chn));
+		sp->rx_dma.enable = false;
+	}
+}
+
+static void sprd_stop_tx(struct uart_port *port)
+{
+	struct sprd_uart_port *sp = container_of(port, struct sprd_uart_port,
+						 port);
 	unsigned int ien, iclr;
 
+	if (sp->tx_dma.enable) {
+		sprd_stop_tx_dma(port);
+		return;
+	}
+
 	iclr = serial_in(port, SPRD_ICLR);
 	ien = serial_in(port, SPRD_IEN);
 
-	ien &= ~(SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT);
-	iclr |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT;
+	iclr |= SPRD_IEN_TX_EMPTY;
+	ien &= ~SPRD_IEN_TX_EMPTY;
 
 	serial_out(port, SPRD_IEN, ien);
 	serial_out(port, SPRD_ICLR, iclr);
 }
 
+static void sprd_start_tx(struct uart_port *port)
+{
+	struct sprd_uart_port *sp = container_of(port, struct sprd_uart_port,
+						 port);
+	unsigned int ien;
+
+	if (sp->tx_dma.enable) {
+		sprd_start_tx_dma(port);
+		return;
+	}
+
+	ien = serial_in(port, SPRD_IEN);
+	if (!(ien & SPRD_IEN_TX_EMPTY)) {
+		ien |= SPRD_IEN_TX_EMPTY;
+		serial_out(port, SPRD_IEN, ien);
+	}
+}
+
 /* The Sprd serial does not support this function. */
 static void sprd_break_ctl(struct uart_port *port, int break_state)
 {
@@ -220,9 +590,16 @@ static int handle_lsr_errors(struct uart_port *port,
 
 static inline void sprd_rx(struct uart_port *port)
 {
+	struct sprd_uart_port *sp = container_of(port, struct sprd_uart_port,
+						 port);
 	struct tty_port *tty = &port->state->port;
 	unsigned int ch, flag, lsr, max_count = SPRD_TIMEOUT;
 
+	if (sp->rx_dma.enable) {
+		sprd_uart_dma_irq(port);
+		return;
+	}
+
 	while ((serial_in(port, SPRD_STS1) & SPRD_RX_FIFO_CNT_MASK) &&
 	       max_count--) {
 		lsr = serial_in(port, SPRD_LSR);
@@ -306,6 +683,25 @@ static irqreturn_t sprd_handle_irq(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+static void sprd_uart_dma_startup(struct uart_port *port,
+				  struct sprd_uart_port *sp)
+{
+	int ret;
+
+	sprd_request_dma(port);
+	if (!(sp->rx_dma.enable || sp->tx_dma.enable))
+		return;
+
+	ret = sprd_start_dma_rx(port);
+	if (ret) {
+		sp->rx_dma.enable = false;
+		dma_release_channel(sp->rx_dma.chn);
+		dev_warn(port->dev, "fail to start RX dma mode\n");
+	}
+
+	sprd_uart_dma_enable(port, true);
+}
+
 static int sprd_startup(struct uart_port *port)
 {
 	int ret = 0;
@@ -334,6 +730,9 @@ static int sprd_startup(struct uart_port *port)
 	/* allocate irq */
 	sp = container_of(port, struct sprd_uart_port, port);
 	snprintf(sp->name, sizeof(sp->name), "sprd_serial%d", port->line);
+
+	sprd_uart_dma_startup(port, sp);
+
 	ret = devm_request_irq(port->dev, port->irq, sprd_handle_irq,
 			       IRQF_SHARED, sp->name, port);
 	if (ret) {
@@ -348,7 +747,9 @@ static int sprd_startup(struct uart_port *port)
 	/* enable interrupt */
 	spin_lock_irqsave(&port->lock, flags);
 	ien = serial_in(port, SPRD_IEN);
-	ien |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT | SPRD_IEN_TIMEOUT;
+	ien |= SPRD_IEN_BREAK_DETECT | SPRD_IEN_TIMEOUT;
+	if (!sp->rx_dma.enable)
+		ien |= SPRD_IEN_RX_FULL;
 	serial_out(port, SPRD_IEN, ien);
 	spin_unlock_irqrestore(&port->lock, flags);
 
@@ -357,6 +758,7 @@ static int sprd_startup(struct uart_port *port)
 
 static void sprd_shutdown(struct uart_port *port)
 {
+	sprd_release_dma(port);
 	serial_out(port, SPRD_IEN, 0);
 	serial_out(port, SPRD_ICLR, ~0);
 	devm_free_irq(port->dev, port->irq, port);
@@ -687,6 +1089,8 @@ static int sprd_remove(struct platform_device *dev)
 	if (!sprd_ports_num)
 		uart_unregister_driver(&sprd_uart_driver);
 
+	sprd_rx_free_buf(sup);
+
 	return 0;
 }
 
@@ -775,6 +1179,14 @@ static int sprd_probe(struct platform_device *pdev)
 	}
 	up->irq = irq;
 
+	/*
+	 * Allocate one dma buffer to prepare for receive transfer, in case
+	 * memory allocation failure at runtime.
+	 */
+	ret = sprd_rx_alloc_buf(sprd_port[index]);
+	if (ret)
+		return ret;
+
 	if (!sprd_ports_num) {
 		ret = uart_register_driver(&sprd_uart_driver);
 		if (ret < 0) {
-- 
1.7.9.5

Re: [PATCH 2/5] dt-bindings: serial: sprd: Add clocks and clocks-names properties

[Rob Herring]

On Tue, 19 Feb 2019 15:31:12 +0800, Baolin Wang wrote:
> From: Lanqing Liu <lanqing.liu@unisoc.com>
> 
> This patch adds clocks and clocks-names properties, which are used to do
> power management for our UART driver.
> 
> Signed-off-by: Lanqing Liu <lanqing.liu@unisoc.com>
> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> ---
>  .../devicetree/bindings/serial/sprd-uart.txt       |   11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 

Reviewed-by: Rob Herring <robh@kernel.org>

Re: [PATCH 4/5] dt-bindings: serial: sprd: Add dma properties to support DMA mode

[Rob Herring]

On Tue, Feb 19, 2019 at 03:31:14PM +0800, Baolin Wang wrote:
> From: Lanqing Liu <lanqing.liu@unisoc.com>
> 
> This patch adds dmas and dma-names properties for the UART DMA mode.
> 
> Signed-off-by: Lanqing Liu <lanqing.liu@unisoc.com>
> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> ---
>  .../devicetree/bindings/serial/sprd-uart.txt       |    6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/serial/sprd-uart.txt b/Documentation/devicetree/bindings/serial/sprd-uart.txt
> index 6eb5863..9ac28f6 100644
> --- a/Documentation/devicetree/bindings/serial/sprd-uart.txt
> +++ b/Documentation/devicetree/bindings/serial/sprd-uart.txt
> @@ -15,12 +15,18 @@ Required properties:
>    UART clock and source clock are optional properties, but enable clock
>    is required.
>  
> +Optional properties:
> +- dma-names: Should contain "tx" for transmit and "rx" for receive channels.

The order here doesn't match the example.

> +- dmas: A list of dma specifiers, one for each entry in dma-names.
> +
>  Example:
>  	uart0: serial@0 {
>  		compatible = "sprd,sc9860-uart",
>  			     "sprd,sc9836-uart";
>  		reg = <0x0 0x100>;
>  		interrupts = <GIC_SPI 2 IRQ_TYPE_LEVEL_HIGH>;
> +		dma-names = "rx", "tx";
> +		dmas = <&ap_dma 19 19>, <&ap_dma 20 20>;
>  		clock-names = "enable", "uart", "source";
>  		clocks = <&clk_ap_apb_gates 9>, <&clk_uart0>, <&ext_26m>;
>  	};
> -- 
> 1.7.9.5
> 

Re: [PATCH 4/5] dt-bindings: serial: sprd: Add dma properties to support DMA mode

[Baolin Wang]

On Fri, 1 Mar 2019 at 03:53, Rob Herring <robh@kernel.org> wrote:
>
> On Tue, Feb 19, 2019 at 03:31:14PM +0800, Baolin Wang wrote:
> > From: Lanqing Liu <lanqing.liu@unisoc.com>
> >
> > This patch adds dmas and dma-names properties for the UART DMA mode.
> >
> > Signed-off-by: Lanqing Liu <lanqing.liu@unisoc.com>
> > Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> > ---
> >  .../devicetree/bindings/serial/sprd-uart.txt       |    6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/serial/sprd-uart.txt b/Documentation/devicetree/bindings/serial/sprd-uart.txt
> > index 6eb5863..9ac28f6 100644
> > --- a/Documentation/devicetree/bindings/serial/sprd-uart.txt
> > +++ b/Documentation/devicetree/bindings/serial/sprd-uart.txt
> > @@ -15,12 +15,18 @@ Required properties:
> >    UART clock and source clock are optional properties, but enable clock
> >    is required.
> >
> > +Optional properties:
> > +- dma-names: Should contain "tx" for transmit and "rx" for receive channels.
>
> The order here doesn't match the example.

Ah, yes, will update new version to fix this. Thanks.

>
> > +- dmas: A list of dma specifiers, one for each entry in dma-names.
> > +
> >  Example:
> >       uart0: serial@0 {
> >               compatible = "sprd,sc9860-uart",
> >                            "sprd,sc9836-uart";
> >               reg = <0x0 0x100>;
> >               interrupts = <GIC_SPI 2 IRQ_TYPE_LEVEL_HIGH>;
> > +             dma-names = "rx", "tx";
> > +             dmas = <&ap_dma 19 19>, <&ap_dma 20 20>;
> >               clock-names = "enable", "uart", "source";
> >               clocks = <&clk_ap_apb_gates 9>, <&clk_uart0>, <&ext_26m>;
> >       };
> > --
> > 1.7.9.5
> >



-- 
Baolin Wang
Best Regards