[PATCH 0/7] tty: serial: msm: Add DMA support and fix bit definitions

[PATCH 0/7] tty: serial: msm: Add DMA support and fix bit definitions

[Ivan T. Ivanov]

Hi,

Following patches add DMA support for UARTDM type of hardware.

Changes have been tested on UARTDM v1.3(APQ8064) and v1.4(APQ8016).

Patches from Gurav were published long ago here[1], I just addressed
remaining comments and coding style issues.

Any comments are welcome.

Regards,
Ivan

Ivan T. Ivanov (5):
  tty: serial: msm: Fix command Stale Event Enable definition
  tty: serial: msm: Add msm prefix to all driver functions
  tty: serial: msm: Add TX DMA support
  tty: serial: msm: Add RX DMA support
  tty: serial: msm: Remove 115.2 Kbps maximum baud rate limitation

Pramod Gurav (2):
  tty: serial: msm: Add mask value for UART_DM registers
  tty: serial: msm: replaces (1 << x) with BIT(x) macro

[1] http://www.spinics.net/lists/linux-serial/msg16874.html


 .../devicetree/bindings/serial/qcom,msm-uartdm.txt |   6 +
 drivers/tty/serial/msm_serial.c                    | 616 +++++++++++++++++++--
 drivers/tty/serial/msm_serial.h                    |  55 +-
 3 files changed, 604 insertions(+), 73 deletions(-)

--
1.9.1

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[PATCH 1/7] tty: serial: msm: Add mask value for UART_DM registers

[Ivan T. Ivanov]

From: Pramod Gurav <gpramod@codeaurora.org>

The bit masks for RFR_LEVEL1 and STALE_TIMEOUT_MSB values in MR1 and
IPR registers respectively are different for UART and UART_DM hardware
cores. We have been using UART core mask values for these. Add the same
for UART_DM core.

There is no bit setting as UART_IPR_RXSTALE_LAST for UART_DM core so do
it only for UART core.

Signed-off-by: Pramod Gurav <gpramod@codeaurora.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Ivan T. Ivanov <ivan.ivanov@linaro.org>
---
 drivers/tty/serial/msm_serial.c | 26 ++++++++++++++++++++------
 drivers/tty/serial/msm_serial.h |  2 ++
 2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index b73889c8ed4b..d08cfd3e1c3a 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -421,7 +421,7 @@ msm_find_best_baud(struct uart_port *port, unsigned int baud)

 static int msm_set_baud_rate(struct uart_port *port, unsigned int baud)
 {
-	unsigned int rxstale, watermark;
+	unsigned int rxstale, watermark, mask;
 	struct msm_port *msm_port = UART_TO_MSM(port);
 	const struct msm_baud_map *entry;

@@ -432,8 +432,15 @@ static int msm_set_baud_rate(struct uart_port *port, unsigned int baud)
 	/* RX stale watermark */
 	rxstale = entry->rxstale;
 	watermark = UART_IPR_STALE_LSB & rxstale;
-	watermark |= UART_IPR_RXSTALE_LAST;
-	watermark |= UART_IPR_STALE_TIMEOUT_MSB & (rxstale << 2);
+	if (msm_port->is_uartdm) {
+		mask = UART_DM_IPR_STALE_TIMEOUT_MSB;
+	} else {
+		watermark |= UART_IPR_RXSTALE_LAST;
+		mask = UART_IPR_STALE_TIMEOUT_MSB;
+	}
+
+	watermark |= mask & (rxstale << 2);
+
 	msm_write(port, watermark, UART_IPR);

 	/* set RX watermark */
@@ -476,7 +483,7 @@ static void msm_init_clock(struct uart_port *port)
 static int msm_startup(struct uart_port *port)
 {
 	struct msm_port *msm_port = UART_TO_MSM(port);
-	unsigned int data, rfr_level;
+	unsigned int data, rfr_level, mask;
 	int ret;

 	snprintf(msm_port->name, sizeof(msm_port->name),
@@ -496,11 +503,18 @@ static int msm_startup(struct uart_port *port)

 	/* set automatic RFR level */
 	data = msm_read(port, UART_MR1);
-	data &= ~UART_MR1_AUTO_RFR_LEVEL1;
+
+	if (msm_port->is_uartdm)
+		mask = UART_DM_MR1_AUTO_RFR_LEVEL1;
+	else
+		mask = UART_MR1_AUTO_RFR_LEVEL1;
+
+	data &= ~mask;
 	data &= ~UART_MR1_AUTO_RFR_LEVEL0;
-	data |= UART_MR1_AUTO_RFR_LEVEL1 & (rfr_level << 2);
+	data |= mask & (rfr_level << 2);
 	data |= UART_MR1_AUTO_RFR_LEVEL0 & rfr_level;
 	msm_write(port, data, UART_MR1);
+
 	return 0;
 }

diff --git a/drivers/tty/serial/msm_serial.h b/drivers/tty/serial/msm_serial.h
index 737f69fe7113..5b7722c3938b 100644
--- a/drivers/tty/serial/msm_serial.h
+++ b/drivers/tty/serial/msm_serial.h
@@ -20,6 +20,7 @@

 #define UART_MR1_AUTO_RFR_LEVEL0	0x3F
 #define UART_MR1_AUTO_RFR_LEVEL1	0x3FF00
+#define UART_DM_MR1_AUTO_RFR_LEVEL1	0xFFFFFF00
 #define UART_MR1_RX_RDY_CTL    		(1 << 7)
 #define UART_MR1_CTS_CTL       		(1 << 6)

@@ -78,6 +79,7 @@
 #define UART_IPR_RXSTALE_LAST		0x20
 #define UART_IPR_STALE_LSB		0x1F
 #define UART_IPR_STALE_TIMEOUT_MSB	0x3FF80
+#define UART_DM_IPR_STALE_TIMEOUT_MSB	0xFFFFFF80

 #define UART_IPR	0x0018
 #define UART_TFWR	0x001C
--
1.9.1

[PATCH 2/7] tty: serial: msm: replaces (1 << x) with BIT(x) macro

[Ivan T. Ivanov]

From: Pramod Gurav <gpramod-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>

Replaces (1 << x) with BIT(x) macro

Signed-off-by: Pramod Gurav <gpramod-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
Reviewed-by: Stephen Boyd <sboyd-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
Signed-off-by: Ivan T. Ivanov <ivan.ivanov-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
---
 drivers/tty/serial/msm_serial.h | 44 ++++++++++++++++++++---------------------
 1 file changed, 22 insertions(+), 22 deletions(-)

diff --git a/drivers/tty/serial/msm_serial.h b/drivers/tty/serial/msm_serial.h
index 5b7722c3938b..60917d30c6b5 100644
--- a/drivers/tty/serial/msm_serial.h
+++ b/drivers/tty/serial/msm_serial.h
@@ -21,11 +21,11 @@
 #define UART_MR1_AUTO_RFR_LEVEL0	0x3F
 #define UART_MR1_AUTO_RFR_LEVEL1	0x3FF00
 #define UART_DM_MR1_AUTO_RFR_LEVEL1	0xFFFFFF00
-#define UART_MR1_RX_RDY_CTL    		(1 << 7)
-#define UART_MR1_CTS_CTL       		(1 << 6)
+#define UART_MR1_RX_RDY_CTL		BIT(7)
+#define UART_MR1_CTS_CTL		BIT(6)

 #define UART_MR2			0x0004
-#define UART_MR2_ERROR_MODE		(1 << 6)
+#define UART_MR2_ERROR_MODE		BIT(6)
 #define UART_MR2_BITS_PER_CHAR		0x30
 #define UART_MR2_BITS_PER_CHAR_5	(0x0 << 4)
 #define UART_MR2_BITS_PER_CHAR_6	(0x1 << 4)
@@ -62,19 +62,19 @@
 #define UART_CR_CMD_STALE_EVENT_ENABLE	(80 << 4)
 #define UART_CR_CMD_FORCE_STALE		(4 << 8)
 #define UART_CR_CMD_RESET_TX_READY	(3 << 8)
-#define UART_CR_TX_DISABLE		(1 << 3)
-#define UART_CR_TX_ENABLE		(1 << 2)
-#define UART_CR_RX_DISABLE		(1 << 1)
-#define UART_CR_RX_ENABLE		(1 << 0)
+#define UART_CR_TX_DISABLE		BIT(3)
+#define UART_CR_TX_ENABLE		BIT(2)
+#define UART_CR_RX_DISABLE		BIT(1)
+#define UART_CR_RX_ENABLE		BIT(0)
 #define UART_CR_CMD_RESET_RXBREAK_START	((1 << 11) | (2 << 4))

 #define UART_IMR		0x0014
-#define UART_IMR_TXLEV		(1 << 0)
-#define UART_IMR_RXSTALE	(1 << 3)
-#define UART_IMR_RXLEV		(1 << 4)
-#define UART_IMR_DELTA_CTS	(1 << 5)
-#define UART_IMR_CURRENT_CTS	(1 << 6)
-#define UART_IMR_RXBREAK_START	(1 << 10)
+#define UART_IMR_TXLEV			BIT(0)
+#define UART_IMR_RXSTALE		BIT(3)
+#define UART_IMR_RXLEV			BIT(4)
+#define UART_IMR_DELTA_CTS		BIT(5)
+#define UART_IMR_CURRENT_CTS		BIT(6)
+#define UART_IMR_RXBREAK_START		BIT(10)

 #define UART_IPR_RXSTALE_LAST		0x20
 #define UART_IPR_STALE_LSB		0x1F
@@ -98,20 +98,20 @@
 #define UART_TEST_CTRL		0x0050

 #define UART_SR			0x0008
-#define UART_SR_HUNT_CHAR	(1 << 7)
-#define UART_SR_RX_BREAK	(1 << 6)
-#define UART_SR_PAR_FRAME_ERR	(1 << 5)
-#define UART_SR_OVERRUN		(1 << 4)
-#define UART_SR_TX_EMPTY	(1 << 3)
-#define UART_SR_TX_READY	(1 << 2)
-#define UART_SR_RX_FULL		(1 << 1)
-#define UART_SR_RX_READY	(1 << 0)
+#define UART_SR_HUNT_CHAR	BIT(7)
+#define UART_SR_RX_BREAK	BIT(6)
+#define UART_SR_PAR_FRAME_ERR	BIT(5)
+#define UART_SR_OVERRUN		BIT(4)
+#define UART_SR_TX_EMPTY	BIT(3)
+#define UART_SR_TX_READY	BIT(2)
+#define UART_SR_RX_FULL		BIT(1)
+#define UART_SR_RX_READY	BIT(0)

 #define UART_RF			0x000C
 #define UARTDM_RF		0x0070
 #define UART_MISR		0x0010
 #define UART_ISR		0x0014
-#define UART_ISR_TX_READY	(1 << 7)
+#define UART_ISR_TX_READY	BIT(7)

 #define UARTDM_RXFS		0x50
 #define UARTDM_RXFS_BUF_SHIFT	0x7
--
1.9.1

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[PATCH 4/7] tty: serial: msm: Add msm prefix to all driver functions

[Ivan T. Ivanov]

Make function naming consistent across this driver.
No functional changes.

Signed-off-by: Ivan T. Ivanov <ivan.ivanov-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
---
 drivers/tty/serial/msm_serial.c | 38 +++++++++++++++++++-------------------
 1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index d08cfd3e1c3a..1c2a02634853 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -57,7 +57,7 @@ struct msm_port {
 	bool			break_detected;
 };

-static inline void wait_for_xmitr(struct uart_port *port)
+static inline void msm_wait_for_xmitr(struct uart_port *port)
 {
 	while (!(msm_read(port, UART_SR) & UART_SR_TX_EMPTY)) {
 		if (msm_read(port, UART_ISR) & UART_ISR_TX_READY)
@@ -99,7 +99,7 @@ static void msm_enable_ms(struct uart_port *port)
 	msm_write(port, msm_port->imr, UART_IMR);
 }

-static void handle_rx_dm(struct uart_port *port, unsigned int misr)
+static void msm_handle_rx_dm(struct uart_port *port, unsigned int misr)
 {
 	struct tty_port *tport = &port->state->port;
 	unsigned int sr;
@@ -171,7 +171,7 @@ static void handle_rx_dm(struct uart_port *port, unsigned int misr)
 	msm_write(port, UART_CR_CMD_STALE_EVENT_ENABLE, UART_CR);
 }

-static void handle_rx(struct uart_port *port)
+static void msm_handle_rx(struct uart_port *port)
 {
 	struct tty_port *tport = &port->state->port;
 	unsigned int sr;
@@ -224,14 +224,14 @@ static void handle_rx(struct uart_port *port)
 	spin_lock(&port->lock);
 }

-static void reset_dm_count(struct uart_port *port, int count)
+static void msm_reset_dm_count(struct uart_port *port, int count)
 {
-	wait_for_xmitr(port);
+	msm_wait_for_xmitr(port);
 	msm_write(port, count, UARTDM_NCF_TX);
 	msm_read(port, UARTDM_NCF_TX);
 }

-static void handle_tx(struct uart_port *port)
+static void msm_handle_tx(struct uart_port *port)
 {
 	struct circ_buf *xmit = &port->state->xmit;
 	struct msm_port *msm_port = UART_TO_MSM(port);
@@ -250,13 +250,13 @@ static void handle_tx(struct uart_port *port)

 	if (port->x_char) {
 		if (msm_port->is_uartdm)
-			reset_dm_count(port, tx_count + 1);
+			msm_reset_dm_count(port, tx_count + 1);

 		iowrite8_rep(tf, &port->x_char, 1);
 		port->icount.tx++;
 		port->x_char = 0;
 	} else if (tx_count && msm_port->is_uartdm) {
-		reset_dm_count(port, tx_count);
+		msm_reset_dm_count(port, tx_count);
 	}

 	while (tf_pointer < tx_count) {
@@ -290,7 +290,7 @@ static void handle_tx(struct uart_port *port)
 		uart_write_wakeup(port);
 }

-static void handle_delta_cts(struct uart_port *port)
+static void msm_handle_delta_cts(struct uart_port *port)
 {
 	msm_write(port, UART_CR_CMD_RESET_CTS, UART_CR);
 	port->icount.cts++;
@@ -314,14 +314,14 @@ static irqreturn_t msm_irq(int irq, void *dev_id)

 	if (misr & (UART_IMR_RXLEV | UART_IMR_RXSTALE)) {
 		if (msm_port->is_uartdm)
-			handle_rx_dm(port, misr);
+			msm_handle_rx_dm(port, misr);
 		else
-			handle_rx(port);
+			msm_handle_rx(port);
 	}
 	if (misr & UART_IMR_TXLEV)
-		handle_tx(port);
+		msm_handle_tx(port);
 	if (misr & UART_IMR_DELTA_CTS)
-		handle_delta_cts(port);
+		msm_handle_delta_cts(port);

 	msm_write(port, msm_port->imr, UART_IMR); /* restore interrupt */
 	spin_unlock(&port->lock);
@@ -779,7 +779,7 @@ static void msm_poll_put_char(struct uart_port *port, unsigned char c)
 	msm_write(port, 0, UART_IMR);

 	if (msm_port->is_uartdm)
-		reset_dm_count(port, 1);
+		msm_reset_dm_count(port, 1);

 	/* Wait until FIFO is empty */
 	while (!(msm_read(port, UART_SR) & UART_SR_TX_READY))
@@ -853,7 +853,7 @@ static struct msm_port msm_uart_ports[] = {

 #define UART_NR	ARRAY_SIZE(msm_uart_ports)

-static inline struct uart_port *get_port_from_line(unsigned int line)
+static inline struct uart_port *msm_get_port_from_line(unsigned int line)
 {
 	return &msm_uart_ports[line].uart;
 }
@@ -880,7 +880,7 @@ static void __msm_console_write(struct uart_port *port, const char *s,

 	spin_lock(&port->lock);
 	if (is_uartdm)
-		reset_dm_count(port, count);
+		msm_reset_dm_count(port, count);

 	i = 0;
 	while (i < count) {
@@ -925,7 +925,7 @@ static void msm_console_write(struct console *co, const char *s,

 	BUG_ON(co->index < 0 || co->index >= UART_NR);

-	port = get_port_from_line(co->index);
+	port = msm_get_port_from_line(co->index);
 	msm_port = UART_TO_MSM(port);

 	__msm_console_write(port, s, count, msm_port->is_uartdm);
@@ -942,7 +942,7 @@ static int __init msm_console_setup(struct console *co, char *options)
 	if (unlikely(co->index >= UART_NR || co->index < 0))
 		return -ENXIO;

-	port = get_port_from_line(co->index);
+	port = msm_get_port_from_line(co->index);

 	if (unlikely(!port->membase))
 		return -ENXIO;
@@ -1057,7 +1057,7 @@ static int msm_serial_probe(struct platform_device *pdev)

 	dev_info(&pdev->dev, "msm_serial: detected port #%d\n", line);

-	port = get_port_from_line(line);
+	port = msm_get_port_from_line(line);
 	port->dev = &pdev->dev;
 	msm_port = UART_TO_MSM(port);

--
1.9.1

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Re: [PATCH 4/7] tty: serial: msm: Add msm prefix to all driver functions

[Stephen Boyd]

On 09/12, Ivan T. Ivanov wrote:
> Make function naming consistent across this driver.
> No functional changes.
> 
> Signed-off-by: Ivan T. Ivanov <ivan.ivanov-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> ---

Reviewed-by: Stephen Boyd <sboyd-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>

It would be nice to rename msm_irq to something like msm_uart_irq
too.

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[PATCH 5/7] tty: serial: msm: Add TX DMA support

[Ivan T. Ivanov]

Add transmit DMA support for UARTDM type of controllers.

Tested on APQ8064, which have UARTDM v1.3 and ADM DMA engine
and APQ8016, which have UARTDM v1.4 and BAM DMA engine.

Signed-off-by: Ivan T. Ivanov <ivan.ivanov-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
---
 .../devicetree/bindings/serial/qcom,msm-uartdm.txt |   3 +
 drivers/tty/serial/msm_serial.c                    | 312 +++++++++++++++++++--
 drivers/tty/serial/msm_serial.h                    |   3 +
 3 files changed, 294 insertions(+), 24 deletions(-)

diff --git a/Documentation/devicetree/bindings/serial/qcom,msm-uartdm.txt b/Documentation/devicetree/bindings/serial/qcom,msm-uartdm.txt
index a2114c217376..a600023d9ec1 100644
--- a/Documentation/devicetree/bindings/serial/qcom,msm-uartdm.txt
+++ b/Documentation/devicetree/bindings/serial/qcom,msm-uartdm.txt
@@ -26,6 +26,9 @@ Required properties:
 Optional properties:
 - dmas: Should contain dma specifiers for transmit and receive channels
 - dma-names: Should contain "tx" for transmit and "rx" for receive channels
+- qcom,tx-crci: Identificator <u32> for Client Rate Control Interface to be
+           used with TX DMA channel. Required when using DMA for transmission
+           with UARTDM v1.3 and bellow.

 Note: Aliases may be defined to ensure the correct ordering of the UARTs.
 The alias serialN will result in the UART being assigned port N.  If any
diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index 1c2a02634853..e40611afad09 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -20,6 +20,8 @@
 #endif

 #include <linux/atomic.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
 #include <linux/hrtimer.h>
 #include <linux/module.h>
 #include <linux/io.h>
@@ -39,6 +41,10 @@

 #include "msm_serial.h"

+#define UARTDM_BURST_SIZE	16   /* in bytes */
+#define UARTDM_TX_AIGN(x)	((x) & ~0x3) /* valid for > 1p3 */
+#define UARTDM_TX_MAX		256   /* in bytes, valid for <= 1p3 */
+
 enum {
 	UARTDM_1P1 = 1,
 	UARTDM_1P2,
@@ -46,6 +52,17 @@ enum {
 	UARTDM_1P4,
 };

+struct msm_dma {
+	struct dma_chan		*chan;
+	enum dma_data_direction dir;
+	dma_addr_t		phys;
+	unsigned char		*virt;
+	dma_cookie_t		cookie;
+	u32			enable_bit;
+	unsigned int		count;
+	struct dma_async_tx_descriptor	*desc;
+};
+
 struct msm_port {
 	struct uart_port	uart;
 	char			name[16];
@@ -55,8 +72,93 @@ struct msm_port {
 	int			is_uartdm;
 	unsigned int		old_snap_state;
 	bool			break_detected;
+	struct msm_dma		tx_dma;
 };

+static void msm_handle_tx(struct uart_port *port);
+
+void msm_stop_dma(struct uart_port *port, struct msm_dma *dma)
+{
+	struct device *dev = port->dev;
+	unsigned int mapped;
+	u32 val;
+
+	mapped = dma->count;
+	dma->count = 0;
+
+	dmaengine_terminate_all(dma->chan);
+
+	/*
+	 * DMA Stall happens if enqueue and flush command happens concurrently.
+	 * For example before changing the baud rate/protocol configuration and
+	 * sending flush command to ADM, disable the channel of UARTDM.
+	 * Note: should not reset the receiver here immediately as it is not
+	 * suggested to do disable/reset or reset/disable at the same time.
+	 */
+	val = msm_read(port, UARTDM_DMEN);
+	val &= ~dma->enable_bit;
+	msm_write(port, val, UARTDM_DMEN);
+
+	if (mapped)
+		dma_unmap_single(dev, dma->phys, mapped, dma->dir);
+}
+
+static void msm_release_dma(struct msm_port *msm_port)
+{
+	struct msm_dma *dma;
+
+	dma = &msm_port->tx_dma;
+	if (dma->chan) {
+		msm_stop_dma(&msm_port->uart, dma);
+		dma_release_channel(dma->chan);
+	}
+
+	memset(dma, 0, sizeof(*dma));
+}
+
+static void msm_request_tx_dma(struct msm_port *msm_port, resource_size_t base)
+{
+	struct device *dev = msm_port->uart.dev;
+	struct dma_slave_config conf;
+	struct msm_dma *dma;
+	u32 crci = 0;
+	int ret;
+
+	dma = &msm_port->tx_dma;
+
+	/* allocate DMA resources, if available */
+	dma->chan = dma_request_slave_channel_reason(dev, "tx");
+	if (IS_ERR(dma->chan))
+		goto no_tx;
+
+	of_property_read_u32(dev->of_node, "qcom,tx-crci", &crci);
+
+	memset(&conf, 0, sizeof(conf));
+	conf.direction = DMA_MEM_TO_DEV;
+	conf.device_fc = true;
+	conf.dst_addr = base + UARTDM_TF;
+	conf.dst_maxburst = UARTDM_BURST_SIZE;
+	conf.slave_id = crci;
+
+	ret = dmaengine_slave_config(dma->chan, &conf);
+	if (ret)
+		goto rel_tx;
+
+	dma->dir = DMA_TO_DEVICE;
+
+	if (msm_port->is_uartdm < UARTDM_1P4)
+		dma->enable_bit = UARTDM_DMEN_TX_DM_ENABLE;
+	else
+		dma->enable_bit = UARTDM_DMEN_TX_BAM_ENABLE;
+
+	return;
+
+rel_tx:
+	dma_release_channel(dma->chan);
+no_tx:
+	memset(dma, 0, sizeof(*dma));
+}
+
 static inline void msm_wait_for_xmitr(struct uart_port *port)
 {
 	while (!(msm_read(port, UART_SR) & UART_SR_TX_EMPTY)) {
@@ -78,11 +180,132 @@ static void msm_stop_tx(struct uart_port *port)
 static void msm_start_tx(struct uart_port *port)
 {
 	struct msm_port *msm_port = UART_TO_MSM(port);
+	struct msm_dma *dma = &msm_port->tx_dma;
+
+	/* Already started in DMA mode */
+	if (dma->count)
+		return;
+
+	msm_port->imr |= UART_IMR_TXLEV;
+	msm_write(port, msm_port->imr, UART_IMR);
+}
+
+static void msm_reset_dm_count(struct uart_port *port, int count)
+{
+	msm_wait_for_xmitr(port);
+	msm_write(port, count, UARTDM_NCF_TX);
+	msm_read(port, UARTDM_NCF_TX);
+}
+
+static void msm_complete_tx_dma(void *args)
+{
+	struct msm_port *msm_port = args;
+	struct uart_port *port = &msm_port->uart;
+	struct circ_buf *xmit = &port->state->xmit;
+	struct msm_dma *dma = &msm_port->tx_dma;
+	struct dma_tx_state state;
+	enum dma_status status;
+	unsigned long flags;
+	unsigned int count;
+	u32 val;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	/* Already stopped */
+	if (!dma->count)
+		goto done;
+
+	status = dmaengine_tx_status(dma->chan, dma->cookie, &state);

+	dma_unmap_single(port->dev, dma->phys, dma->count, dma->dir);
+
+	val = msm_read(port, UARTDM_DMEN);
+	val &= ~dma->enable_bit;
+	msm_write(port, val, UARTDM_DMEN);
+
+	if (msm_port->is_uartdm > UARTDM_1P3) {
+		msm_write(port, UART_CR_CMD_RESET_TX, UART_CR);
+		msm_write(port, UART_CR_TX_ENABLE, UART_CR);
+	}
+
+	count = dma->count - state.residue;
+	port->icount.tx += count;
+	dma->count = 0;
+
+	xmit->tail += count;
+	xmit->tail &= UART_XMIT_SIZE - 1;
+
+	/* Restore "Tx FIFO below watermark" interrupt */
 	msm_port->imr |= UART_IMR_TXLEV;
 	msm_write(port, msm_port->imr, UART_IMR);
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+
+	msm_handle_tx(port);
+done:
+	spin_unlock_irqrestore(&port->lock, flags);
 }

+static int msm_handle_tx_dma(struct msm_port *msm_port, unsigned int count)
+{
+	struct circ_buf *xmit = &msm_port->uart.state->xmit;
+	struct uart_port *port = &msm_port->uart;
+	struct msm_dma *dma = &msm_port->tx_dma;
+	void *cpu_addr;
+	int ret;
+	u32 val;
+
+	cpu_addr = &xmit->buf[xmit->tail];
+
+	dma->phys = dma_map_single(port->dev, cpu_addr, count, dma->dir);
+	ret = dma_mapping_error(port->dev, dma->phys);
+	if (ret)
+		return ret;
+
+	dma->desc = dmaengine_prep_slave_single(dma->chan, dma->phys,
+						count, DMA_MEM_TO_DEV,
+						DMA_PREP_INTERRUPT |
+						DMA_PREP_FENCE);
+	if (!dma->desc) {
+		ret = -EIO;
+		goto unmap;
+	}
+
+	dma->desc->callback = msm_complete_tx_dma;
+	dma->desc->callback_param = msm_port;
+
+	dma->cookie = dmaengine_submit(dma->desc);
+	ret = dma_submit_error(dma->cookie);
+	if (ret)
+		goto unmap;
+
+	/*
+	 * Using DMA complete for Tx FIFO reload, no need for
+	 * "Tx FIFO below watermark" one, disable it
+	 */
+	msm_port->imr &= ~UART_IMR_TXLEV;
+	msm_write(port, msm_port->imr, UART_IMR);
+
+	dma->count = count;
+
+	val = msm_read(port, UARTDM_DMEN);
+	val |= dma->enable_bit;
+
+	if (msm_port->is_uartdm < UARTDM_1P4)
+		msm_write(port, val, UARTDM_DMEN);
+
+	msm_reset_dm_count(port, count);
+
+	if (msm_port->is_uartdm > UARTDM_1P3)
+		msm_write(port, val, UARTDM_DMEN);
+
+	dma_async_issue_pending(dma->chan);
+	return 0;
+unmap:
+	dma_unmap_single(port->dev, dma->phys, count, dma->dir);
+	return ret;
+}
 static void msm_stop_rx(struct uart_port *port)
 {
 	struct msm_port *msm_port = UART_TO_MSM(port);
@@ -224,18 +447,11 @@ static void msm_handle_rx(struct uart_port *port)
 	spin_lock(&port->lock);
 }

-static void msm_reset_dm_count(struct uart_port *port, int count)
-{
-	msm_wait_for_xmitr(port);
-	msm_write(port, count, UARTDM_NCF_TX);
-	msm_read(port, UARTDM_NCF_TX);
-}
-
-static void msm_handle_tx(struct uart_port *port)
+static void msm_handle_tx_pio(struct uart_port *port, unsigned int tx_count)
 {
 	struct circ_buf *xmit = &port->state->xmit;
 	struct msm_port *msm_port = UART_TO_MSM(port);
-	unsigned int tx_count, num_chars;
+	unsigned int num_chars;
 	unsigned int tf_pointer = 0;
 	void __iomem *tf;

@@ -244,20 +460,8 @@ static void msm_handle_tx(struct uart_port *port)
 	else
 		tf = port->membase + UART_TF;

-	tx_count = uart_circ_chars_pending(xmit);
-	tx_count = min3(tx_count, (unsigned int)UART_XMIT_SIZE - xmit->tail,
-			port->fifosize);
-
-	if (port->x_char) {
-		if (msm_port->is_uartdm)
-			msm_reset_dm_count(port, tx_count + 1);
-
-		iowrite8_rep(tf, &port->x_char, 1);
-		port->icount.tx++;
-		port->x_char = 0;
-	} else if (tx_count && msm_port->is_uartdm) {
+	if (tx_count && msm_port->is_uartdm)
 		msm_reset_dm_count(port, tx_count);
-	}

 	while (tf_pointer < tx_count) {
 		int i;
@@ -290,6 +494,59 @@ static void msm_handle_tx(struct uart_port *port)
 		uart_write_wakeup(port);
 }

+static void msm_handle_tx(struct uart_port *port)
+{
+	struct msm_port *msm_port = UART_TO_MSM(port);
+	struct circ_buf *xmit = &msm_port->uart.state->xmit;
+	struct msm_dma *dma = &msm_port->tx_dma;
+	unsigned int pio_count, dma_count, dma_min;
+	void __iomem *tf;
+	int err = 0;
+
+	if (port->x_char) {
+		if (msm_port->is_uartdm)
+			tf = port->membase + UARTDM_TF;
+		else
+			tf = port->membase + UART_TF;
+
+		if (msm_port->is_uartdm)
+			msm_reset_dm_count(port, 1);
+
+		iowrite8_rep(tf, &port->x_char, 1);
+		port->icount.tx++;
+		port->x_char = 0;
+		return;
+	}
+
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+		msm_stop_tx(port);
+		return;
+	}
+
+	pio_count = CIRC_CNT(xmit->head, xmit->tail, UART_XMIT_SIZE);
+	dma_count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+
+	dma_min = 1;	/* Always DMA */
+	if (msm_port->is_uartdm > UARTDM_1P3) {
+		dma_count = UARTDM_TX_AIGN(dma_count);
+		dma_min = UARTDM_BURST_SIZE;
+	} else {
+		if (dma_count > UARTDM_TX_MAX)
+			dma_count = UARTDM_TX_MAX;
+	}
+
+	if (pio_count > port->fifosize)
+		pio_count = port->fifosize;
+
+	if (!dma->chan || dma_count < dma_min)
+		msm_handle_tx_pio(port, pio_count);
+	else
+		err = msm_handle_tx_dma(msm_port, dma_count);
+
+	if (err)	/* fall back to PIO mode */
+		msm_handle_tx_pio(port, pio_count);
+}
+
 static void msm_handle_delta_cts(struct uart_port *port)
 {
 	msm_write(port, UART_CR_CMD_RESET_CTS, UART_CR);
@@ -301,9 +558,10 @@ static irqreturn_t msm_irq(int irq, void *dev_id)
 {
 	struct uart_port *port = dev_id;
 	struct msm_port *msm_port = UART_TO_MSM(port);
+	unsigned long flags;
 	unsigned int misr;

-	spin_lock(&port->lock);
+	spin_lock_irqsave(&port->lock, flags);
 	misr = msm_read(port, UART_MISR);
 	msm_write(port, 0, UART_IMR); /* disable interrupt */

@@ -324,7 +582,7 @@ static irqreturn_t msm_irq(int irq, void *dev_id)
 		msm_handle_delta_cts(port);

 	msm_write(port, msm_port->imr, UART_IMR); /* restore interrupt */
-	spin_unlock(&port->lock);
+	spin_unlock_irqrestore(&port->lock, flags);

 	return IRQ_HANDLED;
 }
@@ -515,6 +773,9 @@ static int msm_startup(struct uart_port *port)
 	data |= UART_MR1_AUTO_RFR_LEVEL0 & rfr_level;
 	msm_write(port, data, UART_MR1);

+	if (msm_port->is_uartdm)
+		msm_request_tx_dma(msm_port, msm_port->uart.mapbase);
+
 	return 0;
 }

@@ -525,6 +786,9 @@ static void msm_shutdown(struct uart_port *port)
 	msm_port->imr = 0;
 	msm_write(port, 0, UART_IMR); /* disable interrupts */

+	if (msm_port->is_uartdm)
+		msm_release_dma(msm_port);
+
 	clk_disable_unprepare(msm_port->clk);

 	free_irq(port->irq, port);
diff --git a/drivers/tty/serial/msm_serial.h b/drivers/tty/serial/msm_serial.h
index 223f961f992a..8a5ca6a01de4 100644
--- a/drivers/tty/serial/msm_serial.h
+++ b/drivers/tty/serial/msm_serial.h
@@ -121,6 +121,9 @@
 #define UARTDM_DMEN_RX_SC_ENABLE BIT(5)
 #define UARTDM_DMEN_TX_SC_ENABLE BIT(4)

+#define UARTDM_DMEN_TX_BAM_ENABLE BIT(2)	/* UARTDM_1P4 */
+#define UARTDM_DMEN_TX_DM_ENABLE  BIT(0)	/* < UARTDM_1P4 */
+
 #define UARTDM_DMRX		0x34
 #define UARTDM_NCF_TX		0x40
 #define UARTDM_RX_TOTAL_SNAP	0x38
--
1.9.1

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Re: [PATCH 0/7] tty: serial: msm: Add DMA support and fix bit definitions

[Srinivas Kandagatla]

Hi Ivan,
On 12/09/15 14:02, Ivan T. Ivanov wrote:
> Hi,
>
> Following patches add DMA support for UARTDM type of hardware.
>
> Changes have been tested on UARTDM v1.3(APQ8064) and v1.4(APQ8016).
>
> Patches from Gurav were published long ago here[1], I just addressed
> remaining comments and coding style issues.
>
> Any comments are welcome.
Looks like Magic Sysrq is broken with this patches.

--srini
>
> Regards,
> Ivan
>
> Ivan T. Ivanov (5):
>    tty: serial: msm: Fix command Stale Event Enable definition
>    tty: serial: msm: Add msm prefix to all driver functions
>    tty: serial: msm: Add TX DMA support
>    tty: serial: msm: Add RX DMA support
>    tty: serial: msm: Remove 115.2 Kbps maximum baud rate limitation
>
> Pramod Gurav (2):
>    tty: serial: msm: Add mask value for UART_DM registers
>    tty: serial: msm: replaces (1 << x) with BIT(x) macro
>
> [1] http://www.spinics.net/lists/linux-serial/msg16874.html
>
>
>   .../devicetree/bindings/serial/qcom,msm-uartdm.txt |   6 +
>   drivers/tty/serial/msm_serial.c                    | 616 +++++++++++++++++++--
>   drivers/tty/serial/msm_serial.h                    |  55 +-
>   3 files changed, 604 insertions(+), 73 deletions(-)
>
> --
> 1.9.1
>
> --
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Re: [PATCH 0/7] tty: serial: msm: Add DMA support and fix bit definitions

[Ivan T. Ivanov]

On Fri, 2015-09-25 at 00:27 +0100, Srinivas Kandagatla wrote:
> Hi Ivan,
> On 12/09/15 14:02, Ivan T. Ivanov wrote:
> > Hi,
> > 
> > Following patches add DMA support for UARTDM type of hardware.
> > 
> > Changes have been tested on UARTDM v1.3(APQ8064) and v1.4(APQ8016).
> > 
> > Patches from Gurav were published long ago here[1], I just addressed
> > remaining comments and coding style issues.
> > 
> > Any comments are welcome.
> Looks like Magic Sysrq is broken with this patches.


Will check it shortly.

Thanks,
Ivan

Re: [PATCH 0/7] tty: serial: msm: Add DMA support and fix bit definitions

[Ivan T. Ivanov]

On Fri, 2015-09-25 at 00:27 +0100, Srinivas Kandagatla wrote:
> Hi Ivan,
> On 12/09/15 14:02, Ivan T. Ivanov wrote:
> > Hi,
> > 
> > Following patches add DMA support for UARTDM type of hardware.
> > 
> > Changes have been tested on UARTDM v1.3(APQ8064) and v1.4(APQ8016).
> > 
> > Patches from Gurav were published long ago here[1], I just addressed
> > remaining comments and coding style issues.
> > 
> > Any comments are welcome.
> Looks like Magic Sysrq is broken with this patches.

Oh, sorry. Interrupts have to be enabled during 
SysRq processing. I will send updated patch-set.

Regards,
Ivan

[PATCH 3/7] tty: serial: msm: Fix command Stale Event Enable definition

[Ivan T. Ivanov]

Stale Event Enable command should be 5 not 8, fix this.

Signed-off-by: Ivan T. Ivanov <ivan.ivanov@linaro.org>
---
 drivers/tty/serial/msm_serial.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/msm_serial.h b/drivers/tty/serial/msm_serial.h
index 60917d30c6b5..223f961f992a 100644
--- a/drivers/tty/serial/msm_serial.h
+++ b/drivers/tty/serial/msm_serial.h
@@ -59,7 +59,7 @@
 #define UART_CR_CMD_SET_RFR		(13 << 4)
 #define UART_CR_CMD_RESET_RFR		(14 << 4)
 #define UART_CR_CMD_PROTECTION_EN	(16 << 4)
-#define UART_CR_CMD_STALE_EVENT_ENABLE	(80 << 4)
+#define UART_CR_CMD_STALE_EVENT_ENABLE	(5 << 8)
 #define UART_CR_CMD_FORCE_STALE		(4 << 8)
 #define UART_CR_CMD_RESET_TX_READY	(3 << 8)
 #define UART_CR_TX_DISABLE		BIT(3)
--
1.9.1

Re: [PATCH 3/7] tty: serial: msm: Fix command Stale Event Enable definition

[Stephen Boyd]

On 09/12, Ivan T. Ivanov wrote:
> Stale Event Enable command should be 5 not 8, fix this.
> 
> Signed-off-by: Ivan T. Ivanov <ivan.ivanov@linaro.org>
> ---
>  drivers/tty/serial/msm_serial.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/msm_serial.h b/drivers/tty/serial/msm_serial.h
> index 60917d30c6b5..223f961f992a 100644
> --- a/drivers/tty/serial/msm_serial.h
> +++ b/drivers/tty/serial/msm_serial.h
> @@ -59,7 +59,7 @@
>  #define UART_CR_CMD_SET_RFR		(13 << 4)
>  #define UART_CR_CMD_RESET_RFR		(14 << 4)
>  #define UART_CR_CMD_PROTECTION_EN	(16 << 4)
> -#define UART_CR_CMD_STALE_EVENT_ENABLE	(80 << 4)
> +#define UART_CR_CMD_STALE_EVENT_ENABLE	(5 << 8)

I don't get this one

 5 << 8 == 80 << 4

so this makes no difference.

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a Linux Foundation Collaborative Project

Re: [PATCH 3/7] tty: serial: msm: Fix command Stale Event Enable definition

[Ivan T. Ivanov]

> On Sep 19, 2015, at 2:33 AM, Stephen Boyd <sboyd-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org> wrote:
> 
> On 09/12, Ivan T. Ivanov wrote:
>> Stale Event Enable command should be 5 not 8, fix this.
>> 
>> Signed-off-by: Ivan T. Ivanov <ivan.ivanov-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
>> ---
>> drivers/tty/serial/msm_serial.h | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/drivers/tty/serial/msm_serial.h b/drivers/tty/serial/msm_serial.h
>> index 60917d30c6b5..223f961f992a 100644
>> --- a/drivers/tty/serial/msm_serial.h
>> +++ b/drivers/tty/serial/msm_serial.h
>> @@ -59,7 +59,7 @@
>> #define UART_CR_CMD_SET_RFR		(13 << 4)
>> #define UART_CR_CMD_RESET_RFR		(14 << 4)
>> #define UART_CR_CMD_PROTECTION_EN	(16 << 4)
>> -#define UART_CR_CMD_STALE_EVENT_ENABLE	(80 << 4)
>> +#define UART_CR_CMD_STALE_EVENT_ENABLE	(5 << 8)
> 
> I don't get this one
> 
> 5 << 8 == 80 << 4
> 
> so this makes no difference.


Uh, of course. It is not 0x80. 

Regards,
Ivan--
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[PATCH 6/7] tty: serial: msm: Add RX DMA support

[Ivan T. Ivanov]

Add receive DMA support for UARTDM type of controllers.

Tested on APQ8064, which have UARTDM v1.3 and ADM DMA engine
and APQ8016, which have UARTDM v1.4 and BAM DMA engine.

Signed-off-by: Ivan T. Ivanov <ivan.ivanov@linaro.org>
---
 .../devicetree/bindings/serial/qcom,msm-uartdm.txt |   3 +
 drivers/tty/serial/msm_serial.c                    | 230 ++++++++++++++++++++-
 drivers/tty/serial/msm_serial.h                    |   4 +
 3 files changed, 234 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/serial/qcom,msm-uartdm.txt b/Documentation/devicetree/bindings/serial/qcom,msm-uartdm.txt
index a600023d9ec1..182777fac9a2 100644
--- a/Documentation/devicetree/bindings/serial/qcom,msm-uartdm.txt
+++ b/Documentation/devicetree/bindings/serial/qcom,msm-uartdm.txt
@@ -29,6 +29,9 @@ Optional properties:
 - qcom,tx-crci: Identificator <u32> for Client Rate Control Interface to be
            used with TX DMA channel. Required when using DMA for transmission
            with UARTDM v1.3 and bellow.
+- qcom,rx-crci: Identificator <u32> for Client Rate Control Interface to be
+           used with RX DMA channel. Required when using DMA for reception
+           with UARTDM v1.3 and bellow.

 Note: Aliases may be defined to ensure the correct ordering of the UARTs.
 The alias serialN will result in the UART being assigned port N.  If any
diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index e40611afad09..3f975392ebc0 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -33,6 +33,7 @@
 #include <linux/tty_flip.h>
 #include <linux/serial_core.h>
 #include <linux/serial.h>
+#include <linux/slab.h>
 #include <linux/clk.h>
 #include <linux/platform_device.h>
 #include <linux/delay.h>
@@ -44,6 +45,7 @@
 #define UARTDM_BURST_SIZE	16   /* in bytes */
 #define UARTDM_TX_AIGN(x)	((x) & ~0x3) /* valid for > 1p3 */
 #define UARTDM_TX_MAX		256   /* in bytes, valid for <= 1p3 */
+#define UARTDM_RX_SIZE		(UART_XMIT_SIZE / 4)

 enum {
 	UARTDM_1P1 = 1,
@@ -73,9 +75,11 @@ struct msm_port {
 	unsigned int		old_snap_state;
 	bool			break_detected;
 	struct msm_dma		tx_dma;
+	struct msm_dma		rx_dma;
 };

 static void msm_handle_tx(struct uart_port *port);
+static void msm_start_rx_dma(struct msm_port *msm_port);

 void msm_stop_dma(struct uart_port *port, struct msm_dma *dma)
 {
@@ -114,6 +118,15 @@ static void msm_release_dma(struct msm_port *msm_port)
 	}

 	memset(dma, 0, sizeof(*dma));
+
+	dma = &msm_port->rx_dma;
+	if (dma->chan) {
+		msm_stop_dma(&msm_port->uart, dma);
+		dma_release_channel(dma->chan);
+		kfree(dma->virt);
+	}
+
+	memset(dma, 0, sizeof(*dma));
 }

 static void msm_request_tx_dma(struct msm_port *msm_port, resource_size_t base)
@@ -159,6 +172,54 @@ no_tx:
 	memset(dma, 0, sizeof(*dma));
 }

+static void msm_request_rx_dma(struct msm_port *msm_port, resource_size_t base)
+{
+	struct device *dev = msm_port->uart.dev;
+	struct dma_slave_config conf;
+	struct msm_dma *dma;
+	u32 crci = 0;
+	int ret;
+
+	dma = &msm_port->rx_dma;
+
+	/* allocate DMA resources, if available */
+	dma->chan = dma_request_slave_channel_reason(dev, "rx");
+	if (IS_ERR(dma->chan))
+		goto no_rx;
+
+	of_property_read_u32(dev->of_node, "qcom,rx-crci", &crci);
+
+	dma->virt = kzalloc(UARTDM_RX_SIZE, GFP_KERNEL);
+	if (!dma->virt)
+		goto rel_rx;
+
+	memset(&conf, 0, sizeof(conf));
+	conf.direction = DMA_DEV_TO_MEM;
+	conf.device_fc = true;
+	conf.src_addr = base + UARTDM_RF;
+	conf.src_maxburst = UARTDM_BURST_SIZE;
+	conf.slave_id = crci;
+
+	ret = dmaengine_slave_config(dma->chan, &conf);
+	if (ret)
+		goto err;
+
+	dma->dir = DMA_FROM_DEVICE;
+
+	if (msm_port->is_uartdm < UARTDM_1P4)
+		dma->enable_bit = UARTDM_DMEN_RX_DM_ENABLE;
+	else
+		dma->enable_bit = UARTDM_DMEN_RX_BAM_ENABLE;
+
+	return;
+err:
+	kfree(dma->virt);
+rel_rx:
+	dma_release_channel(dma->chan);
+no_rx:
+	memset(dma, 0, sizeof(*dma));
+}
+
 static inline void msm_wait_for_xmitr(struct uart_port *port)
 {
 	while (!(msm_read(port, UART_SR) & UART_SR_TX_EMPTY)) {
@@ -306,12 +367,149 @@ unmap:
 	dma_unmap_single(port->dev, dma->phys, count, dma->dir);
 	return ret;
 }
+
+static void msm_complete_rx_dma(void *args)
+{
+	struct msm_port *msm_port = args;
+	struct uart_port *port = &msm_port->uart;
+	struct tty_port *tport = &port->state->port;
+	struct msm_dma *dma = &msm_port->rx_dma;
+	int count = 0, i, sysrq;
+	unsigned long flags;
+	u32 val;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	/* Already stopped */
+	if (!dma->count)
+		goto done;
+
+	val = msm_read(port, UARTDM_DMEN);
+	val &= ~dma->enable_bit;
+	msm_write(port, val, UARTDM_DMEN);
+
+	/* Restore interrupts */
+	msm_port->imr |= UART_IMR_RXLEV | UART_IMR_RXSTALE;
+	msm_write(port, msm_port->imr, UART_IMR);
+
+	if (msm_read(port, UART_SR) & UART_SR_OVERRUN) {
+		port->icount.overrun++;
+		tty_insert_flip_char(tport, 0, TTY_OVERRUN);
+		msm_write(port, UART_CR_CMD_RESET_ERR, UART_CR);
+	}
+
+	count = msm_read(port, UARTDM_RX_TOTAL_SNAP);
+
+	port->icount.rx += count;
+
+	dma->count = 0;
+
+	dma_unmap_single(port->dev, dma->phys, UARTDM_RX_SIZE, dma->dir);
+
+	for (i = 0; i < count; i++) {
+		char flag = TTY_NORMAL;
+
+		if (msm_port->break_detected && dma->virt[i] == 0) {
+			port->icount.brk++;
+			flag = TTY_BREAK;
+			msm_port->break_detected = false;
+			if (uart_handle_break(port))
+				continue;
+		}
+
+		if (!(port->read_status_mask & UART_SR_RX_BREAK))
+			flag = TTY_NORMAL;
+
+		sysrq = uart_handle_sysrq_char(port, dma->virt[i]);
+		if (!sysrq)
+			tty_insert_flip_char(tport, dma->virt[i], flag);
+	}
+
+	msm_start_rx_dma(msm_port);
+done:
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	if (count)
+		tty_flip_buffer_push(tport);
+}
+
+static void msm_start_rx_dma(struct msm_port *msm_port)
+{
+	struct msm_dma *dma = &msm_port->rx_dma;
+	struct uart_port *uart = &msm_port->uart;
+	u32 val;
+	int ret;
+
+	if (!dma->chan)
+		return;
+
+	dma->phys = dma_map_single(uart->dev, dma->virt,
+				   UARTDM_RX_SIZE, dma->dir);
+	ret = dma_mapping_error(uart->dev, dma->phys);
+	if (ret)
+		return;
+
+	dma->desc = dmaengine_prep_slave_single(dma->chan, dma->phys,
+						UARTDM_RX_SIZE, DMA_DEV_TO_MEM,
+						DMA_PREP_INTERRUPT);
+	if (!dma->desc)
+		goto unmap;
+
+	dma->desc->callback = msm_complete_rx_dma;
+	dma->desc->callback_param = msm_port;
+
+	dma->cookie = dmaengine_submit(dma->desc);
+	ret = dma_submit_error(dma->cookie);
+	if (ret)
+		goto unmap;
+	/*
+	 * Using DMA for FIFO off-load, no need for "Rx FIFO over
+	 * watermark" or "stale" interrupts, disable them
+	 */
+	msm_port->imr &= ~(UART_IMR_RXLEV | UART_IMR_RXSTALE);
+
+	/*
+	 * Well, when DMA is ADM3 engine(implied by <= UARTDM v1.3),
+	 * we need RXSTALE to flush input DMA fifo to memory
+	 */
+	if (msm_port->is_uartdm < UARTDM_1P4)
+		msm_port->imr |= UART_IMR_RXSTALE;
+
+	msm_write(uart, msm_port->imr, UART_IMR);
+
+	dma->count = UARTDM_RX_SIZE;
+
+	dma_async_issue_pending(dma->chan);
+
+	msm_write(uart, UART_CR_CMD_RESET_STALE_INT, UART_CR);
+	msm_write(uart, UART_CR_CMD_STALE_EVENT_ENABLE, UART_CR);
+
+	val = msm_read(uart, UARTDM_DMEN);
+	val |= dma->enable_bit;
+
+	if (msm_port->is_uartdm < UARTDM_1P4)
+		msm_write(uart, val, UARTDM_DMEN);
+
+	msm_write(uart, UARTDM_RX_SIZE, UARTDM_DMRX);
+
+	if (msm_port->is_uartdm > UARTDM_1P3)
+		msm_write(uart, val, UARTDM_DMEN);
+
+	return;
+unmap:
+	dma_unmap_single(uart->dev, dma->phys, UARTDM_RX_SIZE, dma->dir);
+}
+
 static void msm_stop_rx(struct uart_port *port)
 {
 	struct msm_port *msm_port = UART_TO_MSM(port);
+	struct msm_dma *dma = &msm_port->rx_dma;

 	msm_port->imr &= ~(UART_IMR_RXLEV | UART_IMR_RXSTALE);
 	msm_write(port, msm_port->imr, UART_IMR);
+
+	if (dma->chan)
+		msm_stop_dma(port, dma);
 }

 static void msm_enable_ms(struct uart_port *port)
@@ -392,6 +590,9 @@ static void msm_handle_rx_dm(struct uart_port *port, unsigned int misr)
 		msm_write(port, UART_CR_CMD_RESET_STALE_INT, UART_CR);
 	msm_write(port, 0xFFFFFF, UARTDM_DMRX);
 	msm_write(port, UART_CR_CMD_STALE_EVENT_ENABLE, UART_CR);
+
+	/* Try to use DMA */
+	msm_start_rx_dma(msm_port);
 }

 static void msm_handle_rx(struct uart_port *port)
@@ -558,8 +759,10 @@ static irqreturn_t msm_irq(int irq, void *dev_id)
 {
 	struct uart_port *port = dev_id;
 	struct msm_port *msm_port = UART_TO_MSM(port);
+	struct msm_dma *dma = &msm_port->rx_dma;
 	unsigned long flags;
 	unsigned int misr;
+	u32 val;

 	spin_lock_irqsave(&port->lock, flags);
 	misr = msm_read(port, UART_MISR);
@@ -571,10 +774,21 @@ static irqreturn_t msm_irq(int irq, void *dev_id)
 	}

 	if (misr & (UART_IMR_RXLEV | UART_IMR_RXSTALE)) {
-		if (msm_port->is_uartdm)
+		if (dma->count) {
+			val = UART_CR_CMD_STALE_EVENT_DISABLE;
+			msm_write(port, val, UART_CR);
+			val = UART_CR_CMD_RESET_STALE_INT;
+			msm_write(port, val, UART_CR);
+			/*
+			 * Flush DMA input fifo to memory, this will also
+			 * trigger DMA RX completion
+			 */
+			dmaengine_terminate_all(dma->chan);
+		} else if (msm_port->is_uartdm) {
 			msm_handle_rx_dm(port, misr);
-		else
+		} else {
 			msm_handle_rx(port);
+		}
 	}
 	if (misr & UART_IMR_TXLEV)
 		msm_handle_tx(port);
@@ -773,8 +987,10 @@ static int msm_startup(struct uart_port *port)
 	data |= UART_MR1_AUTO_RFR_LEVEL0 & rfr_level;
 	msm_write(port, data, UART_MR1);

-	if (msm_port->is_uartdm)
+	if (msm_port->is_uartdm) {
 		msm_request_tx_dma(msm_port, msm_port->uart.mapbase);
+		msm_request_rx_dma(msm_port, msm_port->uart.mapbase);
+	}

 	return 0;
 }
@@ -797,11 +1013,16 @@ static void msm_shutdown(struct uart_port *port)
 static void msm_set_termios(struct uart_port *port, struct ktermios *termios,
 			    struct ktermios *old)
 {
+	struct msm_port *msm_port = UART_TO_MSM(port);
+	struct msm_dma *dma = &msm_port->rx_dma;
 	unsigned long flags;
 	unsigned int baud, mr;

 	spin_lock_irqsave(&port->lock, flags);

+	if (dma->chan) /* Terminate if any */
+		msm_stop_dma(port, dma);
+
 	/* calculate and set baud rate */
 	baud = uart_get_baud_rate(port, termios, old, 300, 115200);
 	baud = msm_set_baud_rate(port, baud);
@@ -866,6 +1087,9 @@ static void msm_set_termios(struct uart_port *port, struct ktermios *termios,

 	uart_update_timeout(port, termios->c_cflag, baud);

+	/* Try to use DMA */
+	msm_start_rx_dma(msm_port);
+
 	spin_unlock_irqrestore(&port->lock, flags);
 }

diff --git a/drivers/tty/serial/msm_serial.h b/drivers/tty/serial/msm_serial.h
index 8a5ca6a01de4..bc1d7b39eba8 100644
--- a/drivers/tty/serial/msm_serial.h
+++ b/drivers/tty/serial/msm_serial.h
@@ -59,6 +59,7 @@
 #define UART_CR_CMD_SET_RFR		(13 << 4)
 #define UART_CR_CMD_RESET_RFR		(14 << 4)
 #define UART_CR_CMD_PROTECTION_EN	(16 << 4)
+#define UART_CR_CMD_STALE_EVENT_DISABLE	(6 << 8)
 #define UART_CR_CMD_STALE_EVENT_ENABLE	(5 << 8)
 #define UART_CR_CMD_FORCE_STALE		(4 << 8)
 #define UART_CR_CMD_RESET_TX_READY	(3 << 8)
@@ -124,6 +125,9 @@
 #define UARTDM_DMEN_TX_BAM_ENABLE BIT(2)	/* UARTDM_1P4 */
 #define UARTDM_DMEN_TX_DM_ENABLE  BIT(0)	/* < UARTDM_1P4 */

+#define UARTDM_DMEN_RX_BAM_ENABLE BIT(3)	/* UARTDM_1P4 */
+#define UARTDM_DMEN_RX_DM_ENABLE  BIT(1)	/* < UARTDM_1P4 */
+
 #define UARTDM_DMRX		0x34
 #define UARTDM_NCF_TX		0x40
 #define UARTDM_RX_TOTAL_SNAP	0x38
--
1.9.1

[PATCH 7/7] tty: serial: msm: Remove 115.2 Kbps maximum baud rate limitation

[Ivan T. Ivanov]

UART controller is capable to perform transfers up to 4 Mbps.
Remove artificial 115.2 Kbps limitation.

Signed-off-by: Ivan T. Ivanov <ivan.ivanov@linaro.org>
---
 drivers/tty/serial/msm_serial.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index 3f975392ebc0..223514979685 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -880,6 +880,7 @@ msm_find_best_baud(struct uart_port *port, unsigned int baud)
 		{    3, 0xdd,  8 },
 		{    2, 0xee, 16 },
 		{    1, 0xff, 31 },
+		{    0, 0xff, 31 },
 	};

 	divisor = uart_get_divisor(port, baud);
@@ -891,16 +892,29 @@ msm_find_best_baud(struct uart_port *port, unsigned int baud)
 	return entry; /* Default to smallest divider */
 }

-static int msm_set_baud_rate(struct uart_port *port, unsigned int baud)
+static int msm_set_baud_rate(struct uart_port *port, unsigned int baud,
+			     unsigned long *saved_flags)
 {
 	unsigned int rxstale, watermark, mask;
 	struct msm_port *msm_port = UART_TO_MSM(port);
 	const struct msm_baud_map *entry;
+	unsigned long flags;

 	entry = msm_find_best_baud(port, baud);

 	msm_write(port, entry->code, UART_CSR);

+	if (baud > 460800)
+		port->uartclk = baud * 16;
+
+	flags = *saved_flags;
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	clk_set_rate(msm_port->clk, port->uartclk);
+
+	spin_lock_irqsave(&port->lock, flags);
+	*saved_flags = flags;
+
 	/* RX stale watermark */
 	rxstale = entry->rxstale;
 	watermark = UART_IPR_STALE_LSB & rxstale;
@@ -1024,8 +1038,8 @@ static void msm_set_termios(struct uart_port *port, struct ktermios *termios,
 		msm_stop_dma(port, dma);

 	/* calculate and set baud rate */
-	baud = uart_get_baud_rate(port, termios, old, 300, 115200);
-	baud = msm_set_baud_rate(port, baud);
+	baud = uart_get_baud_rate(port, termios, old, 300, 4000000);
+	baud = msm_set_baud_rate(port, baud, &flags);
 	if (tty_termios_baud_rate(termios))
 		tty_termios_encode_baud_rate(termios, baud, baud);

--
1.9.1