[PATCH RESEND 0/8] serial: 8250: support hw-based RS485 direction control

[PATCH RESEND 0/8] serial: 8250: support hw-based RS485 direction control

[Wolfram Sang]

Some 8250-variants control the direction pin for RS485 in hardware. Linux has
RS485 support these days, so update the 8250-driver to adhere to that.

Code is based on 3.2-rc4, tested on a OMAP-based custom board with a 16V2750.
A git tree can be found here:

	git://git.pengutronix.de/git/wsa/linux-2.6.git 8250_rs485

There is no code change since the initial post of this series. I updated some
of the patch descriptions, though. A kind-of-ack from Claudio can be found here
[1]. Please consider for inclusion.

Thanks and regards,

   Wolfram

[1] http://lkml.org/lkml/2011/11/24/201

Matthias Fuchs (1):
  serial: 8250: Add ioctl to enable auto rs485 mode with some Exar UARTs

Wolfram Sang (7):
  serial: 8250: replace hardcoded 0xbf with #define
  serial: 8250: save rs485_flags per instance
  serial: 8250: add RX_DURING_TX capability to RS485 mode
  serial: 8250: reject delaying RTS with RS485
  serial: 8250: update rs485 flags with polarity settings
  serial: 8250: add Exar 16V2750 support
  serial: 8250: fix comment about accessing EMSR

 drivers/tty/serial/8250.c   |  143 +++++++++++++++++++++++++++++++++++++++---
 include/linux/serial_core.h |    3 +-
 include/linux/serial_reg.h  |    4 +-
 3 files changed, 137 insertions(+), 13 deletions(-)

-- 
1.7.7.3

[PATCH RESEND 1/8] serial: 8250: replace hardcoded 0xbf with #define

[Wolfram Sang]

Makes it easier to find all occurences requesting CONF_MODE_B.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
---
 drivers/tty/serial/8250.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/tty/serial/8250.c b/drivers/tty/serial/8250.c
index eeadf1b..f8f2320 100644
--- a/drivers/tty/serial/8250.c
+++ b/drivers/tty/serial/8250.c
@@ -2000,7 +2000,7 @@ static int serial8250_startup(struct uart_port *port)
 		serial_outp(up, UART_IER, 0);
 		serial_outp(up, UART_LCR, 0);
 		serial_icr_write(up, UART_CSR, 0); /* Reset the UART */
-		serial_outp(up, UART_LCR, 0xBF);
+		serial_outp(up, UART_LCR, UART_LCR_CONF_MODE_B);
 		serial_outp(up, UART_EFR, UART_EFR_ECB);
 		serial_outp(up, UART_LCR, 0);
 	}
-- 
1.7.7.3

[PATCH RESEND 2/8] serial: 8250: Add ioctl to enable auto rs485 mode with some Exar UARTs

[Wolfram Sang]

From: Matthias Fuchs <mfuchs@ma-fu.de>

Some Exar UARTs support an auto rs485 mode. In this mode
the UART's RTS# pin is activated during transmitting and
can be used to enable a rs485 line driver. This has nothing
to do with attempts to do this by manually asserting/
deasserting handshake lines in software.

Signed-off-by: Matthias Fuchs <mfuchs@ma-fu.de>

[wsa] Replaced 0xbf with define, saved some line-breaks.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
---
 drivers/tty/serial/8250.c  |   68 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/serial_reg.h |    1 +
 2 files changed, 69 insertions(+), 0 deletions(-)

diff --git a/drivers/tty/serial/8250.c b/drivers/tty/serial/8250.c
index f8f2320..920b4df 100644
--- a/drivers/tty/serial/8250.c
+++ b/drivers/tty/serial/8250.c
@@ -38,6 +38,7 @@
 #include <linux/nmi.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
+#include <linux/uaccess.h>
 
 #include <asm/io.h>
 #include <asm/irq.h>
@@ -2698,6 +2699,72 @@ serial8250_type(struct uart_port *port)
 	return uart_config[type].name;
 }
 
+static int serial8250_ioctl_port(struct uart_port *port,
+		      unsigned int cmd, unsigned long arg)
+{
+	struct uart_8250_port *up = (struct uart_8250_port *)port;
+	unsigned long flags;
+
+	switch (cmd) {
+	case TIOCSRS485:
+	{
+		struct serial_rs485 rs485ctrl;
+		unsigned char fctr, lcr;
+
+		if (port->type != PORT_16850)
+			return -ENOTTY;
+
+		if (copy_from_user(&rs485ctrl, (struct serial_rs485 *)arg,
+				   sizeof(rs485ctrl)))
+			return -EFAULT;
+
+		spin_lock_irqsave(&up->port.lock, flags);
+		lcr = serial_inp(up, UART_LCR);
+		serial_outp(up, UART_LCR, UART_LCR_CONF_MODE_B);
+		fctr = serial_inp(up, UART_FCTR);
+		if (rs485ctrl.flags & SER_RS485_ENABLED)
+			fctr |= UART_FCTR_RS485;
+		else
+			fctr &= ~UART_FCTR_RS485;
+		serial_outp(up, UART_FCTR, fctr);
+		serial_outp(up, UART_LCR, lcr);
+		spin_unlock_irqrestore(&up->port.lock, flags);
+		return 0;
+	}
+
+	case TIOCGRS485:
+	{
+		struct serial_rs485 rs485ctrl;
+		unsigned char lcr;
+
+		if (port->type != PORT_16850)
+			return -ENOTTY;
+
+		memset(&rs485ctrl, 0, sizeof(rs485ctrl));
+
+		spin_lock_irqsave(&up->port.lock, flags);
+		lcr = serial_inp(up, UART_LCR);
+		serial_outp(up, UART_LCR, UART_LCR_CONF_MODE_B);
+		if (serial_inp(up, UART_FCTR) & UART_FCTR_RS485)
+			rs485ctrl.flags = SER_RS485_ENABLED;
+		else
+			rs485ctrl.flags = 0;
+		serial_outp(up, UART_LCR, lcr);
+		spin_unlock_irqrestore(&up->port.lock, flags);
+
+		if (copy_to_user((struct serial_rs485 *)arg, &rs485ctrl,
+				 sizeof(rs485ctrl)))
+			return -EFAULT;
+		return 0;
+	}
+
+	default:
+		return -ENOIOCTLCMD;
+	}
+
+	return 0;
+}
+
 static struct uart_ops serial8250_pops = {
 	.tx_empty	= serial8250_tx_empty,
 	.set_mctrl	= serial8250_set_mctrl,
@@ -2717,6 +2784,7 @@ static struct uart_ops serial8250_pops = {
 	.request_port	= serial8250_request_port,
 	.config_port	= serial8250_config_port,
 	.verify_port	= serial8250_verify_port,
+	.ioctl		= serial8250_ioctl_port,
 #ifdef CONFIG_CONSOLE_POLL
 	.poll_get_char = serial8250_get_poll_char,
 	.poll_put_char = serial8250_put_poll_char,
diff --git a/include/linux/serial_reg.h b/include/linux/serial_reg.h
index 8ce70d7..fb37c4f 100644
--- a/include/linux/serial_reg.h
+++ b/include/linux/serial_reg.h
@@ -201,6 +201,7 @@
 #define UART_FCTR_RTS_8DELAY	0x03
 #define UART_FCTR_IRDA		0x04  /* IrDa data encode select */
 #define UART_FCTR_TX_INT	0x08  /* Tx interrupt type select */
+#define UART_FCTR_RS485		0x08  /* Auto RS485 mode */
 #define UART_FCTR_TRGA		0x00  /* Tx/Rx 550 trigger table select */
 #define UART_FCTR_TRGB		0x10  /* Tx/Rx 650 trigger table select */
 #define UART_FCTR_TRGC		0x20  /* Tx/Rx 654 trigger table select */
-- 
1.7.7.3

[PATCH RESEND 3/8] serial: 8250: save rs485_flags per instance

[Wolfram Sang]

When set, save RS485 related flags in the private struct. This avoids
mangling with chip registers when reading back the RS485 config. Also,
features can check their configuration at runtime which will be needed
for a later patch.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
---
 drivers/tty/serial/8250.c |   16 +++++-----------
 1 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/drivers/tty/serial/8250.c b/drivers/tty/serial/8250.c
index 920b4df..b5d3248 100644
--- a/drivers/tty/serial/8250.c
+++ b/drivers/tty/serial/8250.c
@@ -154,6 +154,7 @@ struct uart_8250_port {
 	unsigned char		lsr_saved_flags;
 #define MSR_SAVE_FLAGS UART_MSR_ANY_DELTA
 	unsigned char		msr_saved_flags;
+	__u32			rs485_flags;	/* copied from IOCTL */
 };
 
 struct irq_info {
@@ -2729,28 +2730,21 @@ static int serial8250_ioctl_port(struct uart_port *port,
 		serial_outp(up, UART_FCTR, fctr);
 		serial_outp(up, UART_LCR, lcr);
 		spin_unlock_irqrestore(&up->port.lock, flags);
+
+		up->rs485_flags = rs485ctrl.flags;
+
 		return 0;
 	}
 
 	case TIOCGRS485:
 	{
 		struct serial_rs485 rs485ctrl;
-		unsigned char lcr;
 
 		if (port->type != PORT_16850)
 			return -ENOTTY;
 
 		memset(&rs485ctrl, 0, sizeof(rs485ctrl));
-
-		spin_lock_irqsave(&up->port.lock, flags);
-		lcr = serial_inp(up, UART_LCR);
-		serial_outp(up, UART_LCR, UART_LCR_CONF_MODE_B);
-		if (serial_inp(up, UART_FCTR) & UART_FCTR_RS485)
-			rs485ctrl.flags = SER_RS485_ENABLED;
-		else
-			rs485ctrl.flags = 0;
-		serial_outp(up, UART_LCR, lcr);
-		spin_unlock_irqrestore(&up->port.lock, flags);
+		rs485ctrl.flags = up->rs485_flags;
 
 		if (copy_to_user((struct serial_rs485 *)arg, &rs485ctrl,
 				 sizeof(rs485ctrl)))
-- 
1.7.7.3

[PATCH RESEND 4/8] serial: 8250: add RX_DURING_TX capability to RS485 mode

[Wolfram Sang]

To prevent echo in some configurations, make sure we do not read back
when we are sending if RS485 is configured this way. We need to shuffle
stop_rx() around, implement start_rx() and call it in apropriate places.

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
---
 drivers/tty/serial/8250.c |   34 +++++++++++++++++++++++++---------
 1 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/drivers/tty/serial/8250.c b/drivers/tty/serial/8250.c
index b5d3248..6a2f47f 100644
--- a/drivers/tty/serial/8250.c
+++ b/drivers/tty/serial/8250.c
@@ -1304,6 +1304,26 @@ static void autoconfig_irq(struct uart_8250_port *up)
 	up->port.irq = (irq > 0) ? irq : 0;
 }
 
+static void serial8250_stop_rx(struct uart_port *port)
+{
+	struct uart_8250_port *up =
+		container_of(port, struct uart_8250_port, port);
+
+	up->ier &= ~UART_IER_RLSI;
+	up->port.read_status_mask &= ~UART_LSR_DR;
+	serial_out(up, UART_IER, up->ier);
+}
+
+static void serial8250_start_rx(struct uart_port *port)
+{
+	struct uart_8250_port *up =
+		container_of(port, struct uart_8250_port, port);
+
+	up->ier |= UART_IER_RLSI;
+	up->port.read_status_mask |= UART_LSR_DR;
+	serial_out(up, UART_IER, up->ier);
+}
+
 static inline void __stop_tx(struct uart_8250_port *p)
 {
 	if (p->ier & UART_IER_THRI) {
@@ -1326,6 +1346,9 @@ static void serial8250_stop_tx(struct uart_port *port)
 		up->acr |= UART_ACR_TXDIS;
 		serial_icr_write(up, UART_ACR, up->acr);
 	}
+
+	if (!(up->rs485_flags & SER_RS485_RX_DURING_TX))
+		serial8250_start_rx(port);
 }
 
 static void transmit_chars(struct uart_8250_port *up);
@@ -1357,16 +1380,9 @@ static void serial8250_start_tx(struct uart_port *port)
 		up->acr &= ~UART_ACR_TXDIS;
 		serial_icr_write(up, UART_ACR, up->acr);
 	}
-}
 
-static void serial8250_stop_rx(struct uart_port *port)
-{
-	struct uart_8250_port *up =
-		container_of(port, struct uart_8250_port, port);
-
-	up->ier &= ~UART_IER_RLSI;
-	up->port.read_status_mask &= ~UART_LSR_DR;
-	serial_out(up, UART_IER, up->ier);
+	if (!(up->rs485_flags & SER_RS485_RX_DURING_TX))
+		serial8250_stop_rx(port);
 }
 
 static void serial8250_enable_ms(struct uart_port *port)
-- 
1.7.7.3

[PATCH RESEND 5/8] serial: 8250: reject delaying RTS with RS485

[Wolfram Sang]

There might be chips capable of doing this, but for now nothing is implemented,
so reject usage of this feature.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
---
 drivers/tty/serial/8250.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/tty/serial/8250.c b/drivers/tty/serial/8250.c
index 6a2f47f..28b3608 100644
--- a/drivers/tty/serial/8250.c
+++ b/drivers/tty/serial/8250.c
@@ -2735,6 +2735,9 @@ static int serial8250_ioctl_port(struct uart_port *port,
 				   sizeof(rs485ctrl)))
 			return -EFAULT;
 
+		if (rs485ctrl.delay_rts_before_send || rs485ctrl.delay_rts_after_send)
+			return -EOPNOTSUPP;
+
 		spin_lock_irqsave(&up->port.lock, flags);
 		lcr = serial_inp(up, UART_LCR);
 		serial_outp(up, UART_LCR, UART_LCR_CONF_MODE_B);
-- 
1.7.7.3

[PATCH RESEND 6/8] serial: 8250: update rs485 flags with polarity settings

[Wolfram Sang]

Report the only mode we can support with the 16C850.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
---
 drivers/tty/serial/8250.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/tty/serial/8250.c b/drivers/tty/serial/8250.c
index 28b3608..8cf6d76 100644
--- a/drivers/tty/serial/8250.c
+++ b/drivers/tty/serial/8250.c
@@ -2750,6 +2750,9 @@ static int serial8250_ioctl_port(struct uart_port *port,
 		serial_outp(up, UART_LCR, lcr);
 		spin_unlock_irqrestore(&up->port.lock, flags);
 
+		/* only mode supported by the 16C850 */
+		rs485ctrl.flags &= ~SER_RS485_RTS_ON_SEND;
+		rs485ctrl.flags |= SER_RS485_RTS_AFTER_SEND;
 		up->rs485_flags = rs485ctrl.flags;
 
 		return 0;
-- 
1.7.7.3

[PATCH RESEND 7/8] serial: 8250: add Exar 16V2750 support

[Wolfram Sang]

This variant can select the polarity of RTS# when TX is active with
RS485. Add code to support that, too.

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
---
 drivers/tty/serial/8250.c   |   51 +++++++++++++++++++++++++++++++++++++------
 include/linux/serial_core.h |    3 +-
 include/linux/serial_reg.h  |    1 +
 3 files changed, 47 insertions(+), 8 deletions(-)

diff --git a/drivers/tty/serial/8250.c b/drivers/tty/serial/8250.c
index 8cf6d76..5039e60 100644
--- a/drivers/tty/serial/8250.c
+++ b/drivers/tty/serial/8250.c
@@ -247,6 +247,13 @@ static const struct serial8250_config uart_config[] = {
 				  UART_FCR_T_TRIG_10,
 		.flags		= UART_CAP_FIFO | UART_CAP_EFR | UART_CAP_SLEEP,
 	},
+	[PORT_16V2750] = {
+		.name		= "XR16V2750",
+		.fifo_size	= 64,
+		.tx_loadsz	= 32,
+		.fcr		= UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
+		.flags		= UART_CAP_FIFO | UART_CAP_EFR | UART_CAP_SLEEP,
+	},
 	[PORT_16850] = {
 		.name		= "XR16850",
 		.fifo_size	= 128,
@@ -838,6 +845,7 @@ static void autoconfig_has_efr(struct uart_8250_port *up)
 	 * We check for a XR16C850 by setting DLL and DLM to 0, and then
 	 * reading back DLL and DLM.  The chip type depends on the DLM
 	 * value read back:
+	 *  0x0a - XR16V2750
 	 *  0x10 - XR16C850 and the DLL contains the chip revision.
 	 *  0x12 - XR16C2850.
 	 *  0x14 - XR16C854.
@@ -850,6 +858,10 @@ static void autoconfig_has_efr(struct uart_8250_port *up)
 		up->port.type = PORT_16850;
 		return;
 	}
+	if (id2 == 0x0a) {
+		up->port.type = PORT_16V2750;
+		return;
+	}
 
 	/*
 	 * It wasn't an XR16C850.
@@ -2060,7 +2072,7 @@ static int serial8250_startup(struct uart_port *port)
 	/*
 	 * For a XR16C850, we need to set the trigger levels
 	 */
-	if (up->port.type == PORT_16850) {
+	if (up->port.type == PORT_16850 || up->port.type == PORT_16V2750) {
 		unsigned char fctr;
 
 		serial_outp(up, UART_LCR, UART_LCR_CONF_MODE_B);
@@ -2726,9 +2738,9 @@ static int serial8250_ioctl_port(struct uart_port *port,
 	case TIOCSRS485:
 	{
 		struct serial_rs485 rs485ctrl;
-		unsigned char fctr, lcr;
+		unsigned char fctr, lcr, emsr;
 
-		if (port->type != PORT_16850)
+		if (port->type != PORT_16850 && port->type != PORT_16V2750)
 			return -ENOTTY;
 
 		if (copy_from_user(&rs485ctrl, (struct serial_rs485 *)arg,
@@ -2739,6 +2751,34 @@ static int serial8250_ioctl_port(struct uart_port *port,
 			return -EOPNOTSUPP;
 
 		spin_lock_irqsave(&up->port.lock, flags);
+		if (up->port.type == PORT_16V2750) {
+			/* make EMSR visible */
+			serial_outp(up, UART_LCR, UART_LCR_CONF_MODE_B);
+			fctr = serial_inp(up, UART_FCTR);
+			serial_outp(up, UART_FCTR, fctr | UART_FCTR_SCR_SWAP);
+			serial_outp(up, UART_LCR, 0);
+
+			/* set RTS polarity */
+			emsr = serial_inp(up, UART_EMSR) & ~UART_EMSR_RS485_INV;
+			if (rs485ctrl.flags & SER_RS485_RTS_ON_SEND) {
+				emsr |= UART_EMSR_RS485_INV;
+				rs485ctrl.flags &= ~SER_RS485_RTS_AFTER_SEND;
+			} else {
+				rs485ctrl.flags |= SER_RS485_RTS_AFTER_SEND;
+			}
+			serial_outp(up, UART_EMSR, emsr);
+
+			/* make the EMSR invisible */
+			serial_outp(up, UART_LCR, UART_LCR_CONF_MODE_B);
+			fctr = serial_inp(up, UART_FCTR) & ~UART_FCTR_SCR_SWAP;
+			serial_outp(up, UART_FCTR, fctr);
+			serial_outp(up, UART_LCR, 0);
+		} else {
+			/* only mode supported by the 16C850 */
+			rs485ctrl.flags &= ~SER_RS485_RTS_ON_SEND;
+			rs485ctrl.flags |= SER_RS485_RTS_AFTER_SEND;
+		}
+
 		lcr = serial_inp(up, UART_LCR);
 		serial_outp(up, UART_LCR, UART_LCR_CONF_MODE_B);
 		fctr = serial_inp(up, UART_FCTR);
@@ -2750,9 +2790,6 @@ static int serial8250_ioctl_port(struct uart_port *port,
 		serial_outp(up, UART_LCR, lcr);
 		spin_unlock_irqrestore(&up->port.lock, flags);
 
-		/* only mode supported by the 16C850 */
-		rs485ctrl.flags &= ~SER_RS485_RTS_ON_SEND;
-		rs485ctrl.flags |= SER_RS485_RTS_AFTER_SEND;
 		up->rs485_flags = rs485ctrl.flags;
 
 		return 0;
@@ -2762,7 +2799,7 @@ static int serial8250_ioctl_port(struct uart_port *port,
 	{
 		struct serial_rs485 rs485ctrl;
 
-		if (port->type != PORT_16850)
+		if (port->type != PORT_16850 && port->type != PORT_16V2750)
 			return -ENOTTY;
 
 		memset(&rs485ctrl, 0, sizeof(rs485ctrl));
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index eadf33d..72118c5 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -47,7 +47,8 @@
 #define PORT_U6_16550A	19	/* ST-Ericsson U6xxx internal UART */
 #define PORT_TEGRA	20	/* NVIDIA Tegra internal UART */
 #define PORT_XR17D15X	21	/* Exar XR17D15x UART */
-#define PORT_MAX_8250	21	/* max port ID */
+#define PORT_16V2750	22	/* Exar XR16V2750 */
+#define PORT_MAX_8250	22	/* max port ID */
 
 /*
  * ARM specific type numbers.  These are not currently guaranteed
diff --git a/include/linux/serial_reg.h b/include/linux/serial_reg.h
index fb37c4f..0267bab6 100644
--- a/include/linux/serial_reg.h
+++ b/include/linux/serial_reg.h
@@ -216,6 +216,7 @@
 #define UART_EMSR	7	/* Extended Mode Select Register */
 #define UART_EMSR_FIFO_COUNT	0x01  /* Rx/Tx select */
 #define UART_EMSR_ALT_COUNT	0x02  /* Alternating count select */
+#define UART_EMSR_RS485_INV	0x08  /* RS485 RTS output inversion */
 
 /*
  * The Intel XScale on-chip UARTs define these bits
-- 
1.7.7.3

[PATCH RESEND 8/8] serial: 8250: fix comment about accessing EMSR

[Wolfram Sang]

All docs I checked do say LCR should NOT be 0xBF (16c850, 16c854,
16v2750). Fix it according to that, since the only usage of the register
currently implements the revised access method. If somebody later finds
a derivate which actually does need 0xBF to enable that register, we can
update the comment again with precise references.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
---
 include/linux/serial_reg.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/include/linux/serial_reg.h b/include/linux/serial_reg.h
index 0267bab6..0a1beca 100644
--- a/include/linux/serial_reg.h
+++ b/include/linux/serial_reg.h
@@ -211,7 +211,7 @@
 #define UART_FCTR_TX		0x80  /* Programmable trigger mode select */
 
 /*
- * LCR=0xBF, FCTR[6]=1
+ * LCR!=0xBF (some docs say =0), FCTR[6]=1, XR16C85x
  */
 #define UART_EMSR	7	/* Extended Mode Select Register */
 #define UART_EMSR_FIFO_COUNT	0x01  /* Rx/Tx select */
-- 
1.7.7.3

Re: [PATCH RESEND 1/8] serial: 8250: replace hardcoded 0xbf with #define

[Alan Cox]

On Fri,  9 Dec 2011 18:07:13 +0100
Wolfram Sang <w.sang@pengutronix.de> wrote:

> Makes it easier to find all occurences requesting CONF_MODE_B.
> 
> Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>

Acked-by: Alan Cox <alan@linux.intel.com>

That should go in anyway

Re: [PATCH RESEND 2/8] serial: 8250: Add ioctl to enable auto rs485 mode with some Exar UARTs

[Alan Cox]

On Fri,  9 Dec 2011 18:07:14 +0100
Wolfram Sang <w.sang@pengutronix.de> wrote:

> From: Matthias Fuchs <mfuchs@ma-fu.de>
> 
> Some Exar UARTs support an auto rs485 mode. In this mode
> the UART's RTS# pin is activated during transmitting and
> can be used to enable a rs485 line driver. This has nothing
> to do with attempts to do this by manually asserting/
> deasserting handshake lines in software.

Please split this out so that the ioctl handler calls a pair of port->
methods or errors if NULL. That'll future proof it and keep chip specific
stuff out of the direct paths.

Other than that I'm fine with it. Functionality, locking etc.

Alan

Re: [PATCH RESEND 3/8] serial: 8250: save rs485_flags per instance

[Alan Cox]

On Fri,  9 Dec 2011 18:07:15 +0100
Wolfram Sang <w.sang@pengutronix.de> wrote:

> When set, save RS485 related flags in the private struct. This avoids
> mangling with chip registers when reading back the RS485 config. Also,
> features can check their configuration at runtime which will be needed
> for a later patch.

Ok thats what I get for reading in order - so the #2 problem is ok when
its folded together

Re: [PATCH RESEND 6/8] serial: 8250: update rs485 flags with polarity settings

[Alan Cox]

On Fri,  9 Dec 2011 18:07:18 +0100
Wolfram Sang <w.sang@pengutronix.de> wrote:

> Report the only mode we can support with the 16C850.
> 
> Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
> ---
>  drivers/tty/serial/8250.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250.c b/drivers/tty/serial/8250.c
> index 28b3608..8cf6d76 100644
> --- a/drivers/tty/serial/8250.c
> +++ b/drivers/tty/serial/8250.c
> @@ -2750,6 +2750,9 @@ static int serial8250_ioctl_port(struct uart_port *port,
>  		serial_outp(up, UART_LCR, lcr);
>  		spin_unlock_irqrestore(&up->port.lock, flags);
>  
> +		/* only mode supported by the 16C850 */
> +		rs485ctrl.flags &= ~SER_RS485_RTS_ON_SEND;
> +		rs485ctrl.flags |= SER_RS485_RTS_AFTER_SEND;
>  		up->rs485_flags = rs485ctrl.flags;

Chip specific stuff all wants to be in a port method so while #3 sorts
out much of #2 this goes back to wanting port-> methods and flags to
avoid assumptions about chip types in the core bits.

#7 really makes the point why it is needed.

So pardon the confused series of review comments but I think the summary
is port->ops for RS485 stuff please.

Re: [PATCH RESEND 0/8] serial: 8250: support hw-based RS485 direction control

[Claudio Scordino]

Il 09/12/2011 18:07, Wolfram Sang ha scritto:
> Some 8250-variants control the direction pin for RS485 in hardware. Linux has
> RS485 support these days, so update the 8250-driver to adhere to that.
>
> Code is based on 3.2-rc4, tested on a OMAP-based custom board with a 16V2750.
> A git tree can be found here:
>
> 	git://git.pengutronix.de/git/wsa/linux-2.6.git 8250_rs485
>
> There is no code change since the initial post of this series. I updated some
> of the patch descriptions, though. A kind-of-ack from Claudio can be found here
> [1]. Please consider for inclusion.


Hi Wolfram,

	since the code has not been changed, my opinion remains that it is fine 
and it should enter mainline.

Best regards,

	Claudio