[PATCH 02/14] ARM : SAMSUNG : Add RS485 support.

[PATCH 02/14] ARM : SAMSUNG : Add RS485 support.

[Paul Schilling]

Add RS485 tranmit/recieve control line capabilities
This RS485 driver uses two methodes to determine if the transmit
should be disabled.

1.  It uses a timer and polling to determine when transmit has completed.
2.  Optionally uses a token used to terminate the message to be used in
    the recieve interrupt to disable the transmit.

Option 1 alone can be used but doesn't garentee that the transmit line
wont be disabled within 1 to 2 character times depending on system load.

This patch adds an additional variable to the serial RS-485 struct so
that a program can change the terminate token value via the IOCTL.

Signed-off-by: Paul Schilling <paul.s.schilling@gmail.com>
---
 arch/arm/plat-samsung/include/plat/regs-serial.h |    7 +
 drivers/tty/serial/Kconfig                       |   16 +
 drivers/tty/serial/samsung.c                     |  738 ++++++++++++++++++++--
 drivers/tty/serial/samsung.h                     |   15 +
 include/linux/serial.h                           |    5 +-
 5 files changed, 722 insertions(+), 59 deletions(-)

diff --git a/arch/arm/plat-samsung/include/plat/regs-serial.h b/arch/arm/plat-samsung/include/plat/regs-serial.h
index bac36fa..9618e7d 100644
--- a/arch/arm/plat-samsung/include/plat/regs-serial.h
+++ b/arch/arm/plat-samsung/include/plat/regs-serial.h
@@ -261,6 +261,13 @@ struct s3c2410_uartcfg {
 
 	struct s3c24xx_uart_clksrc *clocks;
 	unsigned int		    clocks_size;
+
+#ifdef CONFIG_SAMSUNG_HAS_RS485
+	signed int       gpio_transmit_en;
+	signed int       gpio_receive_en;
+	unsigned char	 enable_token;
+	unsigned char	 token;
+#endif
 };
 
 /* s3c24xx_uart_devs
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 4dcb37b..dab33c2 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -464,6 +464,22 @@ config SERIAL_SAMSUNG_UARTS
 	  Select the number of available UART ports for the Samsung S3C
 	  serial driver
 	
+config SAMSUNG_HAS_RS485
+	bool "Enable RS485 support for Samsung"
+	depends on SERIAL_SAMSUNG && (MACH_CONDOR2440 || MACH_CONDOR2416 || MACH_MINI2440)
+	default y if (MACH_CONDOR2440 || MACH_CONDOR2416)
+	default n if (MACH_MINI2440)
+
+config SAMSUNG_485_LOW_RES_TIMER
+    bool "Samsung RS-485 use low res timer during transmit"
+    depends on SERIAL_SAMSUNG && SAMSUNG_HAS_RS485
+    default n
+    help
+      Use low resolution jiffies at 200 Hz for timer the RS-485
+      transmitter.  This works but doesn't garantee hard realtime.
+      Say no if you need the transmitter off immediatly after sending
+      a string or character.
+
 config SERIAL_SAMSUNG_DEBUG
 	bool "Samsung SoC serial debug"
 	depends on SERIAL_SAMSUNG && DEBUG_LL
diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index 6edafb5..bf61579 100644
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -4,12 +4,16 @@
  * Ben Dooks, Copyright (c) 2003-2008 Simtec Electronics
  *	http://armlinux.simtec.co.uk/
  *
+ * Paul Schilling, Copyright (c) 2011 Ecolab Corp.
+ *  http://www.ecolab.com/
+ *  Added RS-485 support to the Samsung UART driver.
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
 */
 
-/* Hote on 2410 error handling
+/* Note on 2410 error handling
  *
  * The s3c2410 manual has a love/hate affair with the contents of the
  * UERSTAT register in the UART blocks, and keeps marking some of the
@@ -17,7 +21,7 @@
  * it copes with BREAKs properly, so I am happy to ignore the RESERVED
  * feature from the latter versions of the manual.
  *
- * If it becomes aparrent that latter versions of the 2410 remove these
+ * If it becomes apparent that latter versions of the 2410 remove these
  * bits, then action will have to be taken to differentiate the versions
  * and change the policy on BREAK
  *
@@ -42,6 +46,8 @@
 #include <linux/delay.h>
 #include <linux/clk.h>
 #include <linux/cpufreq.h>
+#include <linux/uaccess.h>
+#include <linux/gpio.h>
 
 #include <asm/irq.h>
 
@@ -66,11 +72,27 @@
 /* flag to ignore all characters coming in */
 #define RXSTAT_DUMMY_READ (0x10000000)
 
+static struct s3c24xx_uart_port s3c24xx_serial_ports[CONFIG_SERIAL_SAMSUNG_UARTS];
+
+
 static inline struct s3c24xx_uart_port *to_ourport(struct uart_port *port)
 {
 	return container_of(port, struct s3c24xx_uart_port, port);
 }
 
+static inline struct s3c24xx_uart_info *s3c24xx_port_to_info(struct uart_port *port)
+{
+	return to_ourport(port)->info;
+}
+
+static inline struct s3c2410_uartcfg *s3c24xx_port_to_cfg(struct uart_port *port)
+{
+	if (port->dev == NULL)
+		return NULL;
+
+	return (struct s3c2410_uartcfg *)port->dev->platform_data;
+}
+
 /* translate a port to the device name */
 
 static inline const char *s3c24xx_serial_portname(struct uart_port *port)
@@ -83,6 +105,22 @@ static int s3c24xx_serial_txempty_nofifo(struct uart_port *port)
 	return (rd_regl(port, S3C2410_UTRSTAT) & S3C2410_UTRSTAT_TXE);
 }
 
+#ifdef CONFIG_SAMSUNG_HAS_RS485
+/* Get the current transmit fifo count */
+static int s3c24xx_serial_tx_getfifocnt(struct s3c24xx_uart_port *ourport)
+{
+	struct s3c24xx_uart_info *info = ourport->info;
+	unsigned long ufstat = rd_regl(&(ourport->port), S3C2410_UFSTAT);
+
+	/* If FIFO is full then return FIFO size. */
+	if (ufstat & info->tx_fifofull)
+		return info->fifosize;
+
+	/* Else return number of entries in the FIFO. */
+	return (ufstat & info->tx_fifomask) >> info->tx_fifoshift;
+}
+#endif
+
 static void s3c24xx_serial_rx_enable(struct uart_port *port)
 {
 	unsigned long flags;
@@ -121,15 +159,205 @@ static void s3c24xx_serial_rx_disable(struct uart_port *port)
 	spin_unlock_irqrestore(&port->lock, flags);
 }
 
+static void s3c24xx_serial_rx_fifo_enable(
+		struct uart_port *port,
+		unsigned int en)
+{
+	unsigned long flags;
+	unsigned int ucon;
+	static unsigned int last_state = 1;
+/* FIXME */
+	#if 0
+	if (last_state != en) {
+
+		struct s3c2410_uartcfg *cfg = s3c24xx_port_to_cfg(port);
+
+		spin_lock_irqsave(&port->lock, flags);
+
+		ucon = rd_regl(port, S3C2410_UCON);
+
+		ucon &= ~(S3C2440_UFCON_RXTRIG32 | S3C2410_UCON_RXILEVEL);
+
+		if (en) {
+			ucon |= cfg->ucon;
+		}
+
+		wr_regl(port, S3C2410_UCON, ucon);
+
+		spin_unlock_irqrestore(&port->lock, flags);
+	}
+#endif
+}
+
+#ifdef CONFIG_SAMSUNG_HAS_RS485
+/* Timer function to toggle RTS when using FAST_TIMER */
+#ifdef SAMSUNG485_LOW_RES_TIMER
+	static void rs485_toggle_rts_timer_function(unsigned long _data)
+	{
+		struct uart_port *port = (struct uart_port *)_data;
+		struct s3c2410_uartcfg *cfg = s3c24xx_port_to_cfg(port);
+
+		struct s3c24xx_uart_port *ourport = to_ourport(port);
+
+		unsigned long utrstat;
+
+		utrstat = rd_regl(port, S3C2410_UTRSTAT);
+
+		if ((utrstat & S3C2410_UTRSTAT_TXE) ? 1 : 0) {
+			if (cfg->gpio_transmit_en > -1) {
+				gpio_set_value(cfg->gpio_transmit_en, 0);
+			}
+
+			if (cfg->gpio_receive_en > -1) {
+				gpio_set_value(cfg->gpio_receive_en, 0);
+			}
+		} else {
+			/* Set a short timer to toggle RTS */
+			mod_timer(
+					&(ourport->rs485_tx_timer),
+					jiffies + usecs_to_jiffies(
+							ourport->char_time_usec
+							/ 10));
+		}
+	}
+#else
+
+
+static enum hrtimer_restart rs485_toggle_rts_timer_function(
+		struct s3c24xx_uart_port *ourport)
+{
+	struct s3c2410_uartcfg *cfg =
+			s3c24xx_port_to_cfg(&(ourport->port));
+
+	unsigned long utrstat;
+	enum hrtimer_restart ret;
+
+	/* Read UART transmit status register */
+	utrstat = rd_regl(&(ourport->port), S3C2410_UTRSTAT);
+
+	/* Check if the UART and shift register is empty*/
+	if ((utrstat & S3C2410_UTRSTAT_TXE) ? 1 : 0) {
+		/* Is the GPIO valid for RS485  transmit enable*/
+		if (cfg->gpio_transmit_en > -1) {
+			/* Request, Set, Free the transmit GPIO*/
+			gpio_set_value(cfg->gpio_transmit_en, 0);
+		}
+
+		/* Is the GPIO valid for the RS485 receive enable*/
+		if (cfg->gpio_receive_en > -1) {
+			/* Request, Set, Free the receive GPIO*/
+			gpio_set_value(cfg->gpio_receive_en, 0);
+		}
+
+		s3c24xx_serial_rx_fifo_enable(&(ourport->port), 1);
+
+		/* The timer has completed its task now we can disable it. */
+		ret = HRTIMER_NORESTART;
+	} else {
+
+		ktime_t kt;
+
+		if (s3c24xx_serial_tx_getfifocnt(ourport) > 1) {
+			kt = ktime_set(0, ourport->char_time_nanosec);
+			hrtimer_forward(&(ourport->hr_rs485_tx_timer),
+					ourport->hr_rs485_tx_timer.base->softirq_time,
+					kt);
+		} else {
+			kt = ktime_set(0, ourport->char_time_nanosec / 2);
+			hrtimer_forward(&(ourport->hr_rs485_tx_timer),
+					ourport->hr_rs485_tx_timer.base->softirq_time,
+					kt);
+		}
+
+		/* Timer will be enabled after the interrupt context */
+		ret = HRTIMER_RESTART;
+	}
+
+	return ret;
+}
+
+/* Uart 0 RS-485 timer callback */
+enum hrtimer_restart rs485_hr_timer_callback_uart0(struct hrtimer *timer)
+{
+
+	return rs485_toggle_rts_timer_function(&s3c24xx_serial_ports[0]);
+}
+
+/* Uart 0 RS-485 timer callback */
+enum hrtimer_restart rs485_hr_timer_callback_uart1(struct hrtimer *timer)
+{
+
+	return rs485_toggle_rts_timer_function(&s3c24xx_serial_ports[1]);
+}
+
+/* Uart 0 RS-485 timer callback */
+#if CONFIG_SERIAL_SAMSUNG_UARTS > 2
+enum hrtimer_restart rs485_hr_timer_callback_uart2(struct hrtimer *timer)
+{
+
+	return rs485_toggle_rts_timer_function(&s3c24xx_serial_ports[2]);
+}
+#endif
+
+/* Uart 0 RS-485 timer callback */
+#if CONFIG_SERIAL_SAMSUNG_UARTS > 3
+enum hrtimer_restart rs485_hr_timer_callback_uart3(struct hrtimer *timer)
+{
+
+	return rs485_toggle_rts_timer_function(&s3c24xx_serial_ports[3]);
+}
+#endif
+
+
+/* Callback array*/
+enum hrtimer_restart (*callback_list[CONFIG_SERIAL_SAMSUNG_UARTS])(struct hrtimer *) = {
+		&rs485_hr_timer_callback_uart0,
+		&rs485_hr_timer_callback_uart1,
+
+#if CONFIG_SERIAL_SAMSUNG_UARTS > 2
+		&rs485_hr_timer_callback_uart2,
+#endif
+
+#if CONFIG_SERIAL_SAMSUNG_UARTS > 3
+		&rs485_hr_timer_callback_uart3,
+#endif
+};
+
+#endif
+#endif /* CONFIG_SAMSUNG_HAS_RS485 */
+
+
 static void s3c24xx_serial_stop_tx(struct uart_port *port)
 {
 	struct s3c24xx_uart_port *ourport = to_ourport(port);
 
 	if (tx_enabled(port)) {
+#ifdef CONFIG_SAMSUNG_HAS_RS485
+		if (ourport->rs485.flags & SER_RS485_ENABLED) {
+#ifdef CONFIG_SAMSUNG_485_LOW_RES_TIMER
+			/* Set a short timer to toggle RTS */
+			mod_timer(&(ourport->rs485_tx_timer),
+					jiffies + usecs_to_jiffies(ourport->char_time_usec * s3c24xx_serial_tx_getfifocnt(ourport)));
+#else
+			ktime_t kt;
+
+			/* Set time struct to one char time. */
+			kt = ktime_set(0, ourport->char_time_nanosec);
+
+			/* Start the high res timer. */
+			hrtimer_start(&(ourport->hr_rs485_tx_timer), kt, HRTIMER_MODE_REL);
+#endif /* CONFIG_SAMSUNG_485_LOW_RES_TIMER */
+
+			s3c24xx_serial_rx_fifo_enable(port, 0);
+
+		}
+#endif /* CONFIG_SAMSUNG_HAS_RS485 */
+
 		disable_irq_nosync(ourport->tx_irq);
 		tx_enabled(port) = 0;
-		if (port->flags & UPF_CONS_FLOW)
+		if (port->flags & UPF_CONS_FLOW) {
 			s3c24xx_serial_rx_enable(port);
+		}
 	}
 }
 
@@ -137,7 +365,42 @@ static void s3c24xx_serial_start_tx(struct uart_port *port)
 {
 	struct s3c24xx_uart_port *ourport = to_ourport(port);
 
+#ifdef CONFIG_SAMSUNG_HAS_RS485
+	hrtimer_try_to_cancel(&(ourport->hr_rs485_tx_timer));
+#endif
+
 	if (!tx_enabled(port)) {
+#ifdef CONFIG_SAMSUNG_HAS_RS485
+		/* enable RS-485 */
+		if (ourport->rs485.flags & SER_RS485_ENABLED) {
+			struct s3c2410_uartcfg *cfg = s3c24xx_port_to_cfg(port);
+
+			/* Is transmit GPIO valid */
+			if (cfg->gpio_transmit_en > -1) {
+				/* GPIO Request, Config, Direction, Value, and
+				 *  Free the pin*/
+				WARN_ON(s3c_gpio_cfgpin(cfg->gpio_transmit_en,
+						S3C_GPIO_OUTPUT));
+				gpio_direction_output(cfg->gpio_transmit_en, 1);
+				gpio_set_value(cfg->gpio_transmit_en, 1);
+			}
+
+			/* Is receive GPIO valid */
+			if ((cfg->gpio_receive_en > -1) &&
+					(!(ourport->rs485.flags &
+							SER_RS485_ALWAYS_LISTEN
+							))) {
+				/* GPIO Request, Config, Direction, Value, and
+				 *  Free the pin*/
+				WARN_ON(s3c_gpio_cfgpin(cfg->gpio_receive_en,
+						S3C_GPIO_OUTPUT));
+				gpio_direction_output(cfg->gpio_receive_en, 1);
+				gpio_set_value(cfg->gpio_receive_en, 1);
+			}
+
+		}
+#endif /*CONFIG_SAMSUNG_HAS_RS485 */
+
 		if (port->flags & UPF_CONS_FLOW)
 			s3c24xx_serial_rx_disable(port);
 
@@ -162,18 +425,6 @@ static void s3c24xx_serial_enable_ms(struct uart_port *port)
 {
 }
 
-static inline struct s3c24xx_uart_info *s3c24xx_port_to_info(struct uart_port *port)
-{
-	return to_ourport(port)->info;
-}
-
-static inline struct s3c2410_uartcfg *s3c24xx_port_to_cfg(struct uart_port *port)
-{
-	if (port->dev == NULL)
-		return NULL;
-
-	return (struct s3c2410_uartcfg *)port->dev->platform_data;
-}
 
 static int s3c24xx_serial_rx_fifocnt(struct s3c24xx_uart_port *ourport,
 				     unsigned long ufstat)
@@ -186,6 +437,99 @@ static int s3c24xx_serial_rx_fifocnt(struct s3c24xx_uart_port *ourport,
 	return (ufstat & info->rx_fifomask) >> info->rx_fifoshift;
 }
 
+static inline int
+s3c24xx_serial_getsource(struct uart_port *port, struct s3c24xx_uart_clksrc *c)
+{
+	struct s3c24xx_uart_info *info = s3c24xx_port_to_info(port);
+
+	return (info->get_clksrc)(port, c);
+}
+
+static inline int
+s3c24xx_serial_setsource(struct uart_port *port, struct s3c24xx_uart_clksrc *c)
+{
+	struct s3c24xx_uart_info *info = s3c24xx_port_to_info(port);
+
+	return (info->set_clksrc)(port, c);
+}
+
+#ifdef CONFIG_SAMSUNG_HAS_RS485
+static void
+samsung_uart_get_options(struct uart_port *port, int *baud,
+			   int *parity, int *stop, int *bits)
+{
+	struct s3c24xx_uart_clksrc clksrc;
+	struct clk *clk;
+	unsigned int ulcon;
+	unsigned int ucon;
+	unsigned int ubrdiv;
+	unsigned long rate;
+
+	ulcon  = rd_regl(port, S3C2410_ULCON);
+	ucon   = rd_regl(port, S3C2410_UCON);
+	ubrdiv = rd_regl(port, S3C2410_UBRDIV);
+
+	dbg("s3c24xx_serial_get_options: port=%p\n"
+	    "registers: ulcon=%08x, ucon=%08x, ubdriv=%08x\n",
+	    port, ulcon, ucon, ubrdiv);
+
+	if ((ucon & 0xf) != 0) {
+		/* consider the serial port configured if the tx/rx mode set */
+
+		switch (ulcon & S3C2410_LCON_CSMASK) {
+		case S3C2410_LCON_CS5:
+			*bits = 5;
+			break;
+		case S3C2410_LCON_CS6:
+			*bits = 6;
+			break;
+		case S3C2410_LCON_CS7:
+			*bits = 7;
+			break;
+		default:
+		case S3C2410_LCON_CS8:
+			*bits = 8;
+			break;
+		}
+
+		switch (ulcon & S3C2410_LCON_PMASK) {
+		case S3C2410_LCON_PEVEN:
+			*parity = 'e';
+			break;
+
+		case S3C2410_LCON_PODD:
+			*parity = 'o';
+			break;
+
+		case S3C2410_LCON_PNONE:
+		default:
+			*parity = 'n';
+		}
+
+		if (ulcon | S3C2410_LCON_STOPB) {
+			*stop = 2;
+		} else {
+			*stop = 1;
+		}
+
+		/* now calculate the baud rate */
+
+		s3c24xx_serial_getsource(port, &clksrc);
+
+		clk = clk_get(port->dev, clksrc.name);
+		if (!IS_ERR(clk) && clk != NULL)
+			rate = clk_get_rate(clk) / clksrc.divisor;
+		else
+			rate = 1;
+
+
+		*baud = rate / (16 * (ubrdiv + 1));
+		dbg("calculated baud %d\n", *baud);
+	}
+
+}
+#endif /* CONFIG_SAMSUNG_HAS_RS485 */
+
 
 /* ? - where has parity gone?? */
 #define S3C2410_UERSTAT_PARITY (0x1000)
@@ -209,6 +553,33 @@ s3c24xx_serial_rx_chars(int irq, void *dev_id)
 		uerstat = rd_regl(port, S3C2410_UERSTAT);
 		ch = rd_regb(port, S3C2410_URXH);
 
+		if (ourport->rs485.flags & SER_RS485_ENABLED) {
+			struct s3c2410_uartcfg *cfg = s3c24xx_port_to_cfg(port);
+
+#ifdef CONFIG_TEST_485
+			/* Is the GPIO valid for the RS485 receive enable*/
+			if (cfg->gpio_receive_en > -1) {
+				/* Request, Set, Free the receive GPIO*/
+				gpio_set_value(cfg->gpio_receive_en, 1);
+				gpio_set_value(cfg->gpio_receive_en, 0);
+			}
+#endif
+
+			if ((SER_RS485_TOGGLE_ON_TOKEN & ourport->rs485.flags) &&
+					(ourport->rs485.toggle_token == ch)) {
+				/* Is the GPIO valid for RS485
+				 * transmit enable*/
+				if (cfg->gpio_transmit_en > -1) {
+					/* Set the transmit GPIO line*/
+
+					gpio_set_value(cfg->gpio_transmit_en, 0);
+
+				}
+
+				s3c24xx_serial_rx_fifo_enable(port, 1);
+			}
+		}
+
 		if (port->flags & UPF_CONS_FLOW) {
 			int txe = s3c24xx_serial_txempty_nofifo(port);
 
@@ -488,21 +859,7 @@ static struct s3c24xx_uart_clksrc tmp_clksrc = {
 	.divisor	= 1,
 };
 
-static inline int
-s3c24xx_serial_getsource(struct uart_port *port, struct s3c24xx_uart_clksrc *c)
-{
-	struct s3c24xx_uart_info *info = s3c24xx_port_to_info(port);
-
-	return (info->get_clksrc)(port, c);
-}
 
-static inline int
-s3c24xx_serial_setsource(struct uart_port *port, struct s3c24xx_uart_clksrc *c)
-{
-	struct s3c24xx_uart_info *info = s3c24xx_port_to_info(port);
-
-	return (info->set_clksrc)(port, c);
-}
 
 struct baud_calc {
 	struct s3c24xx_uart_clksrc	*clksrc;
@@ -512,6 +869,41 @@ struct baud_calc {
 	struct clk			*src;
 };
 
+#ifdef CONFIG_SAMSUNG_HAS_RS485
+/* Calculate the char_time depending on baudrate, number of bits etc. */
+static void update_char_time(struct uart_port *port)
+{
+
+	int bits = 8;
+	int baud = 9600;
+	int parity = 'n';
+	int stop = 1;
+
+	samsung_uart_get_options(port, &baud, &parity, &stop, &bits);
+
+	/* calc. number of bits / data byte */
+	/* databits + startbit and 1 stopbit */
+	bits++;
+
+	/* 2 stopbits ? */
+	bits += stop;
+
+	/* is parity enabled. */
+	if ('n' != parity) {
+		bits++;
+	}
+
+#ifdef CONFIG_SAMSUNG_485_LOW_RES_TIMER
+	/* calc timeout */
+	to_ourport(port)->char_time_usec = ((1000000 / baud) * bits) + 1;
+#else
+	/* calc timeout */
+	to_ourport(port)->char_time_nanosec = ((1000000000 / baud) * bits) + 1;
+#endif
+}
+
+#endif /*CONFIG_SAMSUNG_HAS_RS485 */
+
 static int s3c24xx_serial_calcbaud(struct baud_calc *calc,
 				   struct uart_port *port,
 				   struct s3c24xx_uart_clksrc *clksrc,
@@ -785,7 +1177,7 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
 	port->ignore_status_mask = 0;
 	if (termios->c_iflag & IGNPAR)
 		port->ignore_status_mask |= S3C2410_UERSTAT_OVERRUN;
-	if (termios->c_iflag & IGNBRK && termios->c_iflag & IGNPAR)
+	if ((termios->c_iflag & IGNBRK) && (termios->c_iflag & IGNPAR))
 		port->ignore_status_mask |= S3C2410_UERSTAT_FRAME;
 
 	/*
@@ -795,6 +1187,12 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
 		port->ignore_status_mask |= RXSTAT_DUMMY_READ;
 
 	spin_unlock_irqrestore(&port->lock, flags);
+
+#ifdef CONFIG_SAMSUNG_HAS_RS485
+	/* Update character time. */
+	update_char_time(port);
+#endif /* CONFIG_SAMSUNG_HAS_RS485 */
+
 }
 
 static const char *s3c24xx_serial_type(struct uart_port *port)
@@ -830,7 +1228,7 @@ static void s3c24xx_serial_config_port(struct uart_port *port, int flags)
 {
 	struct s3c24xx_uart_info *info = s3c24xx_port_to_info(port);
 
-	if (flags & UART_CONFIG_TYPE &&
+	if ((flags & UART_CONFIG_TYPE) &&
 	    s3c24xx_serial_request_port(port) == 0)
 		port->type = info->type;
 }
@@ -849,6 +1247,73 @@ s3c24xx_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
 	return 0;
 }
 
+#ifdef CONFIG_SAMSUNG_HAS_RS485
+/*
+ * Enable RS-485 called by IOCTL.
+ */
+static int
+s3c24xx_serial_enable_rs485(struct uart_port *port, struct serial_rs485 *r)
+{
+	struct s3c2410_uartcfg *cfg = s3c24xx_port_to_cfg(port);
+	struct s3c24xx_uart_port *ourport = to_ourport(port);
+
+	/* Is GPIO valid for transmit enable. */
+	if (cfg->gpio_transmit_en > -1) {
+		/* GPIO Request, Config, Direction, Value, and Free the pin*/
+		gpio_set_value(cfg->gpio_transmit_en, 0);
+	}
+
+	/* Is GPIO valid for receive enable. */
+	if (cfg->gpio_receive_en > -1) {
+		/* GPIO Request, Config, Direction, Value, and Free the pin*/
+		gpio_set_value(cfg->gpio_receive_en, 0);
+	}
+
+	ourport->rs485 = *r;
+
+	/* Maximum delay before RTS equal to 1000 */
+	if (ourport->rs485.delay_rts_before_send >= 1000)
+		ourport->rs485.delay_rts_before_send = 1000;
+
+#if 0
+	dev_info(port., "rts: on send = %i, after = %i, enabled = %i",
+			info->rs485.rts_on_send,
+			info->rs485.rts_after_sent,
+			info->rs485.enabled
+	);
+#endif
+
+	return 0;
+}
+
+
+static int s3c24xx_serial_ioctl(struct uart_port *port, unsigned int cmd, unsigned long arg)
+{
+
+	struct serial_rs485 rs485conf;
+
+	switch (cmd) {
+	case TIOCSRS485:
+		if (copy_from_user(&rs485conf, (struct serial_rs485 *) arg,
+					sizeof(rs485conf)))
+			return -EFAULT;
+
+		s3c24xx_serial_enable_rs485(port, &rs485conf);
+		break;
+
+	case TIOCGRS485:
+		if (copy_to_user((struct serial_rs485 *) arg,
+					&(to_ourport(port)->rs485),
+					sizeof(rs485conf)))
+			return -EFAULT;
+		break;
+
+	default:
+		return -ENOIOCTLCMD;
+	}
+	return 0;
+}
+#endif /*CONFIG_SAMSUNG_HAS_RS485*/
 
 #ifdef CONFIG_SERIAL_SAMSUNG_CONSOLE
 
@@ -877,6 +1342,9 @@ static struct uart_ops s3c24xx_serial_ops = {
 	.request_port	= s3c24xx_serial_request_port,
 	.config_port	= s3c24xx_serial_config_port,
 	.verify_port	= s3c24xx_serial_verify_port,
+#ifdef CONFIG_SAMSUNG_HAS_RS485
+	.ioctl			= s3c24xx_serial_ioctl,
+#endif /* CONFIG_SAMSUNG_HAS_RS485 */
 };
 
 
@@ -955,9 +1423,16 @@ static struct s3c24xx_uart_port s3c24xx_serial_ports[CONFIG_SERIAL_SAMSUNG_UARTS
 static inline int s3c24xx_serial_resetport(struct uart_port *port,
 					   struct s3c2410_uartcfg *cfg)
 {
+	int ret;
 	struct s3c24xx_uart_info *info = s3c24xx_port_to_info(port);
 
-	return (info->reset_port)(port, cfg);
+	ret = (info->reset_port)(port, cfg);
+
+#ifdef CONFIG_SAMSUNG_HAS_RS485
+	update_char_time(port);
+#endif /* CONFIG_SAMSUNG_HAS_RS485 */
+
+	return ret;
 }
 
 
@@ -1077,6 +1552,42 @@ static int s3c24xx_serial_init_port(struct s3c24xx_uart_port *ourport,
 	port->dev	= &platdev->dev;
 	ourport->info	= info;
 
+#ifdef CONFIG_SAMSUNG_HAS_RS485
+
+	dev_info(port->dev, "port TX GPIO (%d)\n", cfg->gpio_transmit_en);
+	dev_info(port->dev, "port TX GPIO (%d)\n", cfg->gpio_receive_en);
+
+	if (cfg->gpio_transmit_en > -1) {
+		/* Setup 485 as default on capable ports.*/
+		ourport->rs485.flags = (SER_RS485_ENABLED | SER_RS485_ALWAYS_LISTEN |
+				(cfg->enable_token ? SER_RS485_TOGGLE_ON_TOKEN : 0));
+		ourport->rs485.toggle_token = cfg->token;
+
+#ifdef CONFIG_SAMSUNG_485_LOW_RES_TIMER
+		dev_info(&(port->dev), "Enable Lo Res Timer\n");
+		setup_timer(&(ourport->rs485_tx_timer),
+				rs485_toggle_rts_timer_function,
+				(unsigned long)port);
+#else
+		dev_info(port->dev, "Enable Hi Res Timer\n");
+
+		/* Initialize HR timer to relative and monotonic mode. */
+		hrtimer_init(&(ourport->hr_rs485_tx_timer),
+				CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+
+		/* register Callback to appropriate UART */
+		ourport->hr_rs485_tx_timer.function =
+				callback_list[ourport->port.line];
+
+#endif
+
+		dev_info(port->dev, "Port (%d) 485 Enabled\n", ourport->port.line);
+	} else {
+		/* disable 485 on ports inacable of mode. */
+		ourport->rs485.flags = 0;
+	}
+#endif /* CONFIG_SAMSUNG_HAS_RS485*/
+
 	/* copy the info in from provided structure */
 	ourport->port.fifosize = info->fifosize;
 
@@ -1137,6 +1648,55 @@ static ssize_t s3c24xx_serial_show_clksrc(struct device *dev,
 
 static DEVICE_ATTR(clock_source, S_IRUGO, s3c24xx_serial_show_clksrc, NULL);
 
+
+#ifdef CONFIG_SAMSUNG_HAS_RS485
+
+static ssize_t s3c24xx_serial_show_485_status(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	int ret = 0;
+	struct uart_port *port = s3c24xx_dev_to_port(dev);
+	struct s3c24xx_uart_port *ourport = to_ourport(port);
+
+	if (ourport->rs485.flags & SER_RS485_ENABLED) {
+		ret = snprintf(buf, PAGE_SIZE, "[Enabled] Disabled\n");
+	} else {
+		ret = snprintf(buf, PAGE_SIZE, "Enabled [Disabled]\n");
+	}
+
+	return ret;
+}
+
+static ssize_t s3c24xx_serial_set_485_mode(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf, size_t count)
+
+{
+	struct uart_port *port = s3c24xx_dev_to_port(dev);
+	struct s3c24xx_uart_port *ourport = to_ourport(port);
+
+	if (!strncmp(buf, "Enabled", 7)) {
+		ourport->rs485.flags |= SER_RS485_ENABLED;
+	} else if (!strncmp(buf, "Disabled", 8)) {
+		ourport->rs485.flags &= ~SER_RS485_ENABLED;
+	} else {
+		dev_err(port->dev, "unknown string\n");
+
+		return -EINVAL;
+	}
+
+	return count;
+
+}
+
+static DEVICE_ATTR(485_status,
+		S_IRUGO | S_IWUSR,
+		s3c24xx_serial_show_485_status,
+		s3c24xx_serial_set_485_mode);
+
+#endif
+
 /* Device driver serial port probe */
 
 static int probe_index;
@@ -1144,8 +1704,10 @@ static int probe_index;
 int s3c24xx_serial_probe(struct platform_device *dev,
 			 struct s3c24xx_uart_info *info)
 {
-	struct s3c24xx_uart_port *ourport;
 	int ret;
+	struct s3c24xx_uart_port *ourport;
+	struct s3c2410_uartcfg *cfg = s3c24xx_dev_to_cfg(&dev->dev);
+
 
 	dbg("s3c24xx_serial_probe(%p, %p) %d\n", dev, info, probe_index);
 
@@ -1170,6 +1732,33 @@ int s3c24xx_serial_probe(struct platform_device *dev,
 	if (ret < 0)
 		dev_err(&dev->dev, "failed to add cpufreq notifier\n");
 
+#ifdef CONFIG_SAMSUNG_HAS_RS485
+
+	ret = device_create_file(&dev->dev, &dev_attr_485_status);
+	if (ret < 0)
+		printk(KERN_ERR "%s: failed to add 485 status attr.\n", __func__);
+
+
+	if (cfg->gpio_transmit_en > -1) {
+		WARN_ON(gpio_request(cfg->gpio_transmit_en, "RS485TX"));
+		WARN_ON(s3c_gpio_cfgpin(cfg->gpio_transmit_en, S3C_GPIO_OUTPUT));
+		gpio_direction_output(cfg->gpio_transmit_en, 0);
+		gpio_set_value(cfg->gpio_transmit_en, 0);
+
+		dev_info(ourport->port.dev, "Initialize TX(%d) GPIO\n", ourport->port.line);
+
+		if (cfg->gpio_receive_en > -1) {
+			WARN_ON(gpio_request(cfg->gpio_receive_en , "RS485RX"));
+			WARN_ON(s3c_gpio_cfgpin(cfg->gpio_receive_en, S3C_GPIO_OUTPUT));
+			gpio_direction_output(cfg->gpio_receive_en, 0);
+			gpio_set_value(cfg->gpio_receive_en, 0);
+
+			dev_info(ourport->port.dev, "Initialize RX(%d) GPIO\n", ourport->port.line);
+		}
+	}
+#endif
+
+
 	return 0;
 
  probe_err:
@@ -1181,8 +1770,33 @@ EXPORT_SYMBOL_GPL(s3c24xx_serial_probe);
 int __devexit s3c24xx_serial_remove(struct platform_device *dev)
 {
 	struct uart_port *port = s3c24xx_dev_to_port(&dev->dev);
+	struct s3c2410_uartcfg *cfg = s3c24xx_dev_to_cfg(&dev->dev);
 
 	if (port) {
+
+#ifdef CONFIG_SAMSUNG_HAS_RS485
+		if (cfg->gpio_transmit_en > -1) {
+			gpio_free(cfg->gpio_transmit_en);
+
+			dev_info(port->dev,
+					"Uninitialize TX(%d) GPIO\n", port->line);
+
+			if (cfg->gpio_receive_en > -1) {
+				gpio_free(cfg->gpio_receive_en);
+
+				dev_info(port->dev,
+						"Uninitialize RX(%d) GPIO\n",
+						port->line);
+			}
+		}
+
+		/* Delete timer after device is removed. */
+#ifdef CONFIG_SAMSUNG_485_LOW_RES_TIMER
+		del_timer_sync(&(to_ourport(port)->rs485_tx_timer));
+#else
+		hrtimer_cancel(&(to_ourport(port)->hr_rs485_tx_timer));
+#endif
+#endif /* CONFIG_SAMSUNG_HAS_RS485 */
 		s3c24xx_serial_cpufreq_deregister(to_ourport(port));
 		device_remove_file(&dev->dev, &dev_attr_clock_source);
 		uart_remove_one_port(&s3c24xx_uart_drv, port);
@@ -1308,9 +1922,33 @@ s3c24xx_serial_console_write(struct console *co, const char *s,
 	uart_console_write(cons_uart, s, count, s3c24xx_serial_console_putchar);
 }
 
+
+/* s3c24xx_serial_init_ports
+ *
+ * initialise the serial ports from the machine provided initialisation
+ * data.
+*/
+
+static int s3c24xx_serial_init_ports(struct s3c24xx_uart_info **info)
+{
+	struct s3c24xx_uart_port *ptr = s3c24xx_serial_ports;
+	struct platform_device **platdev_ptr;
+	int i;
+
+	dbg("s3c24xx_serial_init_ports: initialising ports...\n");
+
+	platdev_ptr = s3c24xx_uart_devs;
+
+	for (i = 0; i < CONFIG_SERIAL_SAMSUNG_UARTS; i++, ptr++, platdev_ptr++) {
+		s3c24xx_serial_init_port(ptr, info[i], *platdev_ptr);
+	}
+
+	return 0;
+}
+
 static void __init
 s3c24xx_serial_get_options(struct uart_port *port, int *baud,
-			   int *parity, int *bits)
+			   int *parity, int *stop, int *bits)
 {
 	struct s3c24xx_uart_clksrc clksrc;
 	struct clk *clk;
@@ -1360,6 +1998,12 @@ s3c24xx_serial_get_options(struct uart_port *port, int *baud,
 			*parity = 'n';
 		}
 
+		if (ulcon | S3C2410_LCON_STOPB) {
+			*stop = 2;
+		} else {
+			*stop = 1;
+		}
+
 		/* now calculate the baud rate */
 
 		s3c24xx_serial_getsource(port, &clksrc);
@@ -1377,29 +2021,6 @@ s3c24xx_serial_get_options(struct uart_port *port, int *baud,
 
 }
 
-/* s3c24xx_serial_init_ports
- *
- * initialise the serial ports from the machine provided initialisation
- * data.
-*/
-
-static int s3c24xx_serial_init_ports(struct s3c24xx_uart_info **info)
-{
-	struct s3c24xx_uart_port *ptr = s3c24xx_serial_ports;
-	struct platform_device **platdev_ptr;
-	int i;
-
-	dbg("s3c24xx_serial_init_ports: initialising ports...\n");
-
-	platdev_ptr = s3c24xx_uart_devs;
-
-	for (i = 0; i < CONFIG_SERIAL_SAMSUNG_UARTS; i++, ptr++, platdev_ptr++) {
-		s3c24xx_serial_init_port(ptr, info[i], *platdev_ptr);
-	}
-
-	return 0;
-}
-
 static int __init
 s3c24xx_serial_console_setup(struct console *co, char *options)
 {
@@ -1408,6 +2029,7 @@ s3c24xx_serial_console_setup(struct console *co, char *options)
 	int bits = 8;
 	int parity = 'n';
 	int flow = 'n';
+	int stop = 1;
 
 	dbg("s3c24xx_serial_console_setup: co=%p (%d), %s\n",
 	    co, co->index, options);
@@ -1436,7 +2058,7 @@ s3c24xx_serial_console_setup(struct console *co, char *options)
 	if (options)
 		uart_parse_options(options, &baud, &parity, &bits, &flow);
 	else
-		s3c24xx_serial_get_options(port, &baud, &parity, &bits);
+		s3c24xx_serial_get_options(port, &baud, &parity, &stop, &bits);
 
 	dbg("s3c24xx_serial_console_setup: baud %d\n", baud);
 
diff --git a/drivers/tty/serial/samsung.h b/drivers/tty/serial/samsung.h
index a69d9a5..f550dc3 100644
--- a/drivers/tty/serial/samsung.h
+++ b/drivers/tty/serial/samsung.h
@@ -4,6 +4,10 @@
  * Ben Dooks, Copyright (c) 2003-2008 Simtec Electronics
  *	http://armlinux.simtec.co.uk/
  *
+ * Paul Schilling, Copyright (c) 2011 Ecolab Corp.
+ * Added RS-485 support to the Samsung driver..
+ *
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
@@ -31,6 +35,7 @@ struct s3c24xx_uart_info {
 
 	/* uart controls */
 	int (*reset_port)(struct uart_port *, struct s3c2410_uartcfg *);
+
 };
 
 struct s3c24xx_uart_port {
@@ -48,6 +53,16 @@ struct s3c24xx_uart_port {
 	struct clk			*baudclk;
 	struct uart_port		port;
 
+	struct serial_rs485	rs485;				/* RS-485 support */
+
+#ifdef CONFIG_SAMSUNG_485_LOW_RES_TIMER
+	unsigned long char_time_usec;			/* The time for 1 char, in micro secs */
+	struct timer_list rs485_tx_timer;
+#else
+	unsigned long char_time_nanosec;	/* The time for 1 char, in nano secs */
+	struct hrtimer  hr_rs485_tx_timer;		/* Timer for RS-485 Receive enable*/
+#endif
+
 #ifdef CONFIG_CPU_FREQ
 	struct notifier_block		freq_transition;
 #endif
diff --git a/include/linux/serial.h b/include/linux/serial.h
index ef91406..826b1c0 100644
--- a/include/linux/serial.h
+++ b/include/linux/serial.h
@@ -211,9 +211,12 @@ struct serial_rs485 {
 #define SER_RS485_RTS_ON_SEND		(1 << 1)
 #define SER_RS485_RTS_AFTER_SEND	(1 << 2)
 #define SER_RS485_RTS_BEFORE_SEND	(1 << 3)
+#define SER_RS485_ALWAYS_LISTEN		(1 << 4)
+#define SER_RS485_TOGGLE_ON_TOKEN	(1 << 5)
 	__u32	delay_rts_before_send;	/* Milliseconds */
 	__u32	delay_rts_after_send;	/* Milliseconds */
-	__u32	padding[5];		/* Memory is cheap, new structs
+	__u32	toggle_token;			/* Token used to toggle to receive */
+	__u32	padding[4];		/* Memory is cheap, new structs
 					   are a royal PITA .. */
 };
 
-- 
1.7.6.4

Re: [PATCH 02/14] ARM : SAMSUNG : Add RS485 support.

[Russell King - ARM Linux]

On Fri, Oct 21, 2011 at 10:46:34PM -0500, Paul Schilling wrote:
> +config SAMSUNG_HAS_RS485
> +	bool "Enable RS485 support for Samsung"
> +	depends on SERIAL_SAMSUNG && (MACH_CONDOR2440 || MACH_CONDOR2416 || MACH_MINI2440)
> +	default y if (MACH_CONDOR2440 || MACH_CONDOR2416)
> +	default n if (MACH_MINI2440)
> +
> +config SAMSUNG_485_LOW_RES_TIMER
> +    bool "Samsung RS-485 use low res timer during transmit"
> +    depends on SERIAL_SAMSUNG && SAMSUNG_HAS_RS485
> +    default n

n is the default, so this doesn't need to be specified.

> +static void s3c24xx_serial_rx_fifo_enable(
> +		struct uart_port *port,
> +		unsigned int en)
> +{
> +	unsigned long flags;
> +	unsigned int ucon;
> +	static unsigned int last_state = 1;
> +/* FIXME */
> +	#if 0
> +	if (last_state != en) {
> +
> +		struct s3c2410_uartcfg *cfg = s3c24xx_port_to_cfg(port);
> +
> +		spin_lock_irqsave(&port->lock, flags);
> +
> +		ucon = rd_regl(port, S3C2410_UCON);
> +
> +		ucon &= ~(S3C2440_UFCON_RXTRIG32 | S3C2410_UCON_RXILEVEL);
> +
> +		if (en) {
> +			ucon |= cfg->ucon;
> +		}
> +
> +		wr_regl(port, S3C2410_UCON, ucon);
> +
> +		spin_unlock_irqrestore(&port->lock, flags);
> +	}
> +#endif

This looks like dead code.

> +		} else {
> +			/* Set a short timer to toggle RTS */
> +			mod_timer(
> +					&(ourport->rs485_tx_timer),
> +					jiffies + usecs_to_jiffies(
> +							ourport->char_time_usec
> +							/ 10));

This could do with being better formatted.  Also, & doesn't need following
parens.

> +	/* Read UART transmit status register */
> +	utrstat = rd_regl(&(ourport->port), S3C2410_UTRSTAT);

Doesn't need the parens.

> +/* Callback array*/
> +enum hrtimer_restart (*callback_list[CONFIG_SERIAL_SAMSUNG_UARTS])(struct hrtimer *) = {
> +		&rs485_hr_timer_callback_uart0,
> +		&rs485_hr_timer_callback_uart1,
> +
> +#if CONFIG_SERIAL_SAMSUNG_UARTS > 2
> +		&rs485_hr_timer_callback_uart2,
> +#endif
> +
> +#if CONFIG_SERIAL_SAMSUNG_UARTS > 3
> +		&rs485_hr_timer_callback_uart3,
> +#endif

Silly indentation - this doesn't need two tabs.

> +};
> +
> +#endif
> +#endif /* CONFIG_SAMSUNG_HAS_RS485 */
> +
> +
>  static void s3c24xx_serial_stop_tx(struct uart_port *port)
>  {
>  	struct s3c24xx_uart_port *ourport = to_ourport(port);
>  
>  	if (tx_enabled(port)) {
> +#ifdef CONFIG_SAMSUNG_HAS_RS485
> +		if (ourport->rs485.flags & SER_RS485_ENABLED) {
> +#ifdef CONFIG_SAMSUNG_485_LOW_RES_TIMER
> +			/* Set a short timer to toggle RTS */
> +			mod_timer(&(ourport->rs485_tx_timer),

Doesn't need parens.

> +					jiffies + usecs_to_jiffies(ourport->char_time_usec * s3c24xx_serial_tx_getfifocnt(ourport)));
> +#else
> +			ktime_t kt;
> +
> +			/* Set time struct to one char time. */
> +			kt = ktime_set(0, ourport->char_time_nanosec);
> +
> +			/* Start the high res timer. */
> +			hrtimer_start(&(ourport->hr_rs485_tx_timer), kt, HRTIMER_MODE_REL);

Doesn't need parens.

> +#endif /* CONFIG_SAMSUNG_485_LOW_RES_TIMER */
> +
> +			s3c24xx_serial_rx_fifo_enable(port, 0);
> +
> +		}
> +#endif /* CONFIG_SAMSUNG_HAS_RS485 */
> +
>  		disable_irq_nosync(ourport->tx_irq);
>  		tx_enabled(port) = 0;
> -		if (port->flags & UPF_CONS_FLOW)
> +		if (port->flags & UPF_CONS_FLOW) {
>  			s3c24xx_serial_rx_enable(port);
> +		}

Why are you reformatting code?

> @@ -785,7 +1177,7 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
>  	port->ignore_status_mask = 0;
>  	if (termios->c_iflag & IGNPAR)
>  		port->ignore_status_mask |= S3C2410_UERSTAT_OVERRUN;
> -	if (termios->c_iflag & IGNBRK && termios->c_iflag & IGNPAR)
> +	if ((termios->c_iflag & IGNBRK) && (termios->c_iflag & IGNPAR))

More code reformatting.

> @@ -830,7 +1228,7 @@ static void s3c24xx_serial_config_port(struct uart_port *port, int flags)
>  {
>  	struct s3c24xx_uart_info *info = s3c24xx_port_to_info(port);
>  
> -	if (flags & UART_CONFIG_TYPE &&
> +	if ((flags & UART_CONFIG_TYPE) &&

And some more.

> +#if 0
> +	dev_info(port., "rts: on send = %i, after = %i, enabled = %i",

That can't be correct - and as its #if 0'd out, either remove this or
fix it to be correct (and use dev_dbg if you want it to be debugging.)

> +static ssize_t s3c24xx_serial_set_485_mode(struct device *dev,
> +		struct device_attribute *attr,
> +		const char *buf, size_t count)
> +
> +{
> +	struct uart_port *port = s3c24xx_dev_to_port(dev);
> +	struct s3c24xx_uart_port *ourport = to_ourport(port);
> +
> +	if (!strncmp(buf, "Enabled", 7)) {
> +		ourport->rs485.flags |= SER_RS485_ENABLED;
> +	} else if (!strncmp(buf, "Disabled", 8)) {

Do you really require the first character to be capitalized?

> +#ifdef CONFIG_SAMSUNG_HAS_RS485
> +
> +	ret = device_create_file(&dev->dev, &dev_attr_485_status);
> +	if (ret < 0)
> +		printk(KERN_ERR "%s: failed to add 485 status attr.\n", __func__);

pr_err() ?  dev_err() ?

Re: [PATCH 02/14] ARM : SAMSUNG : Add RS485 support.

[Paul Schilling]

See Comments inline.

On Sat, Oct 22, 2011 at 8:47 AM, Russell King - ARM Linux
<linux@arm.linux.org.uk> wrote:
> On Fri, Oct 21, 2011 at 10:46:34PM -0500, Paul Schilling wrote:
>> +config SAMSUNG_HAS_RS485
>> +     bool "Enable RS485 support for Samsung"
>> +     depends on SERIAL_SAMSUNG && (MACH_CONDOR2440 || MACH_CONDOR2416 || MACH_MINI2440)
>> +     default y if (MACH_CONDOR2440 || MACH_CONDOR2416)
>> +     default n if (MACH_MINI2440)
>> +
>> +config SAMSUNG_485_LOW_RES_TIMER
>> +    bool "Samsung RS-485 use low res timer during transmit"
>> +    depends on SERIAL_SAMSUNG && SAMSUNG_HAS_RS485
>> +    default n
>
> n is the default, so this doesn't need to be specified.

Sorry I can fix that.

>
>> +static void s3c24xx_serial_rx_fifo_enable(
>> +             struct uart_port *port,
>> +             unsigned int en)
>> +{
>> +     unsigned long flags;
>> +     unsigned int ucon;
>> +     static unsigned int last_state = 1;
>> +/* FIXME */
>> +     #if 0
>> +     if (last_state != en) {
>> +
>> +             struct s3c2410_uartcfg *cfg = s3c24xx_port_to_cfg(port);
>> +
>> +             spin_lock_irqsave(&port->lock, flags);
>> +
>> +             ucon = rd_regl(port, S3C2410_UCON);
>> +
>> +             ucon &= ~(S3C2440_UFCON_RXTRIG32 | S3C2410_UCON_RXILEVEL);
>> +
>> +             if (en) {
>> +                     ucon |= cfg->ucon;
>> +             }
>> +
>> +             wr_regl(port, S3C2410_UCON, ucon);
>> +
>> +             spin_unlock_irqrestore(&port->lock, flags);
>> +     }
>> +#endif
>
> This looks like dead code.

It is broken dead code.  Performance of the RS485 code could be
increased if this code could be made to work.
right now I am forced to leave it in one character per interrupt so
that each character that's received is checked
against the token.  This code was supposed leave it in multi-byte FIFO
mode until the token byte is sent then switch to receiving
one byte at a time until the token is received.

>
>> +             } else {
>> +                     /* Set a short timer to toggle RTS */
>> +                     mod_timer(
>> +                                     &(ourport->rs485_tx_timer),
>> +                                     jiffies + usecs_to_jiffies(
>> +                                                     ourport->char_time_usec
>> +                                                     / 10));
>
> This could do with being better formatted.  Also, & doesn't need following
> parens.

when I ran checkpatch it complained that it exceeded 80 characters.  I
had trouble keeping this line
under 80 characters.

>
>> +     /* Read UART transmit status register */
>> +     utrstat = rd_regl(&(ourport->port), S3C2410_UTRSTAT);
>
> Doesn't need the parens.

I can remove the extra parentheses.

>
>> +/* Callback array*/
>> +enum hrtimer_restart (*callback_list[CONFIG_SERIAL_SAMSUNG_UARTS])(struct hrtimer *) = {
>> +             &rs485_hr_timer_callback_uart0,
>> +             &rs485_hr_timer_callback_uart1,
>> +
>> +#if CONFIG_SERIAL_SAMSUNG_UARTS > 2
>> +             &rs485_hr_timer_callback_uart2,
>> +#endif
>> +
>> +#if CONFIG_SERIAL_SAMSUNG_UARTS > 3
>> +             &rs485_hr_timer_callback_uart3,
>> +#endif
>
> Silly indentation - this doesn't need two tabs.
>
>> +};
>> +
>> +#endif
>> +#endif /* CONFIG_SAMSUNG_HAS_RS485 */
>> +
>> +
>>  static void s3c24xx_serial_stop_tx(struct uart_port *port)
>>  {
>>       struct s3c24xx_uart_port *ourport = to_ourport(port);
>>
>>       if (tx_enabled(port)) {
>> +#ifdef CONFIG_SAMSUNG_HAS_RS485
>> +             if (ourport->rs485.flags & SER_RS485_ENABLED) {
>> +#ifdef CONFIG_SAMSUNG_485_LOW_RES_TIMER
>> +                     /* Set a short timer to toggle RTS */
>> +                     mod_timer(&(ourport->rs485_tx_timer),
>
> Doesn't need parens.
>
>> +                                     jiffies + usecs_to_jiffies(ourport->char_time_usec * s3c24xx_serial_tx_getfifocnt(ourport)));
>> +#else
>> +                     ktime_t kt;
>> +
>> +                     /* Set time struct to one char time. */
>> +                     kt = ktime_set(0, ourport->char_time_nanosec);
>> +
>> +                     /* Start the high res timer. */
>> +                     hrtimer_start(&(ourport->hr_rs485_tx_timer), kt, HRTIMER_MODE_REL);
>
> Doesn't need parens.
>
>> +#endif /* CONFIG_SAMSUNG_485_LOW_RES_TIMER */
>> +
>> +                     s3c24xx_serial_rx_fifo_enable(port, 0);
>> +
>> +             }
>> +#endif /* CONFIG_SAMSUNG_HAS_RS485 */
>> +
>>               disable_irq_nosync(ourport->tx_irq);
>>               tx_enabled(port) = 0;
>> -             if (port->flags & UPF_CONS_FLOW)
>> +             if (port->flags & UPF_CONS_FLOW) {
>>                       s3c24xx_serial_rx_enable(port);
>> +             }
>
> Why are you reformatting code?

I will remove the reformatting of the code.

>
>> @@ -785,7 +1177,7 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
>>       port->ignore_status_mask = 0;
>>       if (termios->c_iflag & IGNPAR)
>>               port->ignore_status_mask |= S3C2410_UERSTAT_OVERRUN;
>> -     if (termios->c_iflag & IGNBRK && termios->c_iflag & IGNPAR)
>> +     if ((termios->c_iflag & IGNBRK) && (termios->c_iflag & IGNPAR))
>
> More code reformatting.
>
>> @@ -830,7 +1228,7 @@ static void s3c24xx_serial_config_port(struct uart_port *port, int flags)
>>  {
>>       struct s3c24xx_uart_info *info = s3c24xx_port_to_info(port);
>>
>> -     if (flags & UART_CONFIG_TYPE &&
>> +     if ((flags & UART_CONFIG_TYPE) &&
>
> And some more.
>
>> +#if 0
>> +     dev_info(port., "rts: on send = %i, after = %i, enabled = %i",
>
> That can't be correct - and as its #if 0'd out, either remove this or
> fix it to be correct (and use dev_dbg if you want it to be debugging.)
>
>> +static ssize_t s3c24xx_serial_set_485_mode(struct device *dev,
>> +             struct device_attribute *attr,
>> +             const char *buf, size_t count)
>> +
>> +{
>> +     struct uart_port *port = s3c24xx_dev_to_port(dev);
>> +     struct s3c24xx_uart_port *ourport = to_ourport(port);
>> +
>> +     if (!strncmp(buf, "Enabled", 7)) {
>> +             ourport->rs485.flags |= SER_RS485_ENABLED;
>> +     } else if (!strncmp(buf, "Disabled", 8)) {
>
> Do you really require the first character to be capitalized?
>
>> +#ifdef CONFIG_SAMSUNG_HAS_RS485
>> +
>> +     ret = device_create_file(&dev->dev, &dev_attr_485_status);
>> +     if (ret < 0)
>> +             printk(KERN_ERR "%s: failed to add 485 status attr.\n", __func__);
>
> pr_err() ?  dev_err() ?
>
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Re: [PATCH 02/14] ARM : SAMSUNG : Add RS485 support.

[Russell King - ARM Linux]

On Sun, Oct 23, 2011 at 12:12:13PM -0500, Paul Schilling wrote:
> On Sat, Oct 22, 2011 at 8:47 AM, Russell King - ARM Linux
> <linux@arm.linux.org.uk> wrote:
> >> +             } else {
> >> +                     /* Set a short timer to toggle RTS */
> >> +                     mod_timer(
> >> +                                     &(ourport->rs485_tx_timer),
> >> +                                     jiffies + usecs_to_jiffies(
> >> +                                                     ourport->char_time_usec
> >> +                                                     / 10));
> >
> > This could do with being better formatted.  Also, & doesn't need following
> > parens.
> 
> when I ran checkpatch it complained that it exceeded 80 characters.  I
> had trouble keeping this line
> under 80 characters.

		} else {
			mod_timer(&our_port->rs485_tx_timer, jiffies +
				  usecs_to_jiffies(ourport->char_time_usec
						   / 10));

is probably a better way to format it.

> >> -             if (port->flags & UPF_CONS_FLOW)
> >> +             if (port->flags & UPF_CONS_FLOW) {
> >>                       s3c24xx_serial_rx_enable(port);
> >> +             }
> >
> > Why are you reformatting code?
> 
> I will remove the reformatting of the code.

If you wish to reformat the code to clean up checkpatch warnings, then that
needs to be a separate patch from any other changes.

Re: [PATCH 02/14] ARM : SAMSUNG : Add RS485 support.

[Alan Cox]

> +config SAMSUNG_HAS_RS485
> +	bool "Enable RS485 support for Samsung"
> +	depends on SERIAL_SAMSUNG && (MACH_CONDOR2440 ||
> MACH_CONDOR2416 || MACH_MINI2440)
> +	default y if (MACH_CONDOR2440 || MACH_CONDOR2416)
> +	default n if (MACH_MINI2440)

There really needs to be more ARM thinking about doing this sort of
stuff at runtime. If you can detect the board type at runtime then you
need to be moving towards kicking board specifics out of the depends,
and treating it as an "include support for this, if the board has it"
so you can move towards less build time only configuration.

> +/* FIXME */
> +	#if 0
> +	if (last_state != en) {
> +

So this doesn't look ready to submit either...


> +		if ((utrstat & S3C2410_UTRSTAT_TXE) ? 1 : 0) {
> +			if (cfg->gpio_transmit_en > -1) {
> +
> gpio_set_value(cfg->gpio_transmit_en, 0);
> +			}

Lots of excess brackets (see CodingStyle) - removing a few of the
excess ones would make it easier to read later.

The later bits become a real mess of ifdefs - much not your fault, the
combination of your ifdefs and existing lack of design push it beyond
ugly and really want addressing.

Re: [PATCH 02/14] ARM : SAMSUNG : Add RS485 support.

[Paul Schilling]

I am working on resubmitting this stuff right now.  I have 14 patches
that should be
broken into more like 20 patches.  Most of them are ARM S3C and
specifically S3C2416 patches.
I am working on a patch right now to fix a Atomic wait in the DMA
code.  That causes
20 milliseconds of no interrupts whenever a sound is played on the samsung S3C
platform.

The code below wasn't supposed to go out and I have patch that removes
that chunk
of code almost ready that just needs testing before I send it.

On Tue, Nov 1, 2011 at 7:18 AM, Alan Cox <alan@linux.intel.com> wrote:
>> +config SAMSUNG_HAS_RS485
>> +     bool "Enable RS485 support for Samsung"
>> +     depends on SERIAL_SAMSUNG && (MACH_CONDOR2440 ||
>> MACH_CONDOR2416 || MACH_MINI2440)
>> +     default y if (MACH_CONDOR2440 || MACH_CONDOR2416)
>> +     default n if (MACH_MINI2440)
>
> There really needs to be more ARM thinking about doing this sort of
> stuff at runtime. If you can detect the board type at runtime then you
> need to be moving towards kicking board specifics out of the depends,
> and treating it as an "include support for this, if the board has it"
> so you can move towards less build time only configuration.
>

The chunk of code that says FIXME is an optimization that could be
implemented to
decrease interrupts by using DMA until the last byte is ready to be
sent.  I have a new
patch that explains in a comment what the code is for.

>> +/* FIXME */
>> +     #if 0
>> +     if (last_state != en) {
>> +
>
> So this doesn't look ready to submit either...
>

I have a patch that I haven't sent yet that fixes the code formating
issues.  I need to compile and test it before I send it out.

>
>> +             if ((utrstat & S3C2410_UTRSTAT_TXE) ? 1 : 0) {
>> +                     if (cfg->gpio_transmit_en > -1) {
>> +
>> gpio_set_value(cfg->gpio_transmit_en, 0);
>> +                     }
>
> Lots of excess brackets (see CodingStyle) - removing a few of the
> excess ones would make it easier to read later.
>
> The later bits become a real mess of ifdefs - much not your fault, the
> combination of your ifdefs and existing lack of design push it beyond
> ugly and really want addressing.
>
>
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Re: [PATCH 02/14] ARM : SAMSUNG : Add RS485 support.

[Paul Schilling]

I need an opinion on two issues before I resubmit the Samsung RS-485 driver.

First of all the driver works.  I have tested it on a logic analyser
and I found that it
switches from transmit to receive in token mode exactly after 1 bit of
idle time as long
as interrupts are kept enabled and nothing tries to wait or sleep
inside of an interrupt.
I found 2 maybe 3 places where this occurs up to 22 milliseconds.

The opinion part...  I needed a timer to switch from transmit to
receive after the FIFO
was empty.  I started by using the low resolution timer using jiffies
first.  I found that
wasn't high enough resolution, so I switched to the Linux HRT.
Currently I have both
versions that can be selected by conditional compile.  Should I just
remove the low
resolution timer completely or leave it in.

Second, I have a chunk of code that if it could be made to work could
off load the
receiving to DMA up to the last couple of bytes then switch back to
interrupts for
the token byte.  Should I leave that code in a #if 0 statement or
should I just delete
it.

Thanks,
Paul Schilling

On Tue, Nov 1, 2011 at 9:57 AM, Paul Schilling
<paul.s.schilling@gmail.com> wrote:
> I am working on resubmitting this stuff right now.  I have 14 patches
> that should be
> broken into more like 20 patches.  Most of them are ARM S3C and
> specifically S3C2416 patches.
> I am working on a patch right now to fix a Atomic wait in the DMA
> code.  That causes
> 20 milliseconds of no interrupts whenever a sound is played on the samsung S3C
> platform.
>
> The code below wasn't supposed to go out and I have patch that removes
> that chunk
> of code almost ready that just needs testing before I send it.
>
> On Tue, Nov 1, 2011 at 7:18 AM, Alan Cox <alan@linux.intel.com> wrote:
>>> +config SAMSUNG_HAS_RS485
>>> +     bool "Enable RS485 support for Samsung"
>>> +     depends on SERIAL_SAMSUNG && (MACH_CONDOR2440 ||
>>> MACH_CONDOR2416 || MACH_MINI2440)
>>> +     default y if (MACH_CONDOR2440 || MACH_CONDOR2416)
>>> +     default n if (MACH_MINI2440)
>>
>> There really needs to be more ARM thinking about doing this sort of
>> stuff at runtime. If you can detect the board type at runtime then you
>> need to be moving towards kicking board specifics out of the depends,
>> and treating it as an "include support for this, if the board has it"
>> so you can move towards less build time only configuration.
>>
>
> The chunk of code that says FIXME is an optimization that could be
> implemented to
> decrease interrupts by using DMA until the last byte is ready to be
> sent.  I have a new
> patch that explains in a comment what the code is for.
>
>>> +/* FIXME */
>>> +     #if 0
>>> +     if (last_state != en) {
>>> +
>>
>> So this doesn't look ready to submit either...
>>
>
> I have a patch that I haven't sent yet that fixes the code formating
> issues.  I need to compile and test it before I send it out.
>
>>
>>> +             if ((utrstat & S3C2410_UTRSTAT_TXE) ? 1 : 0) {
>>> +                     if (cfg->gpio_transmit_en > -1) {
>>> +
>>> gpio_set_value(cfg->gpio_transmit_en, 0);
>>> +                     }
>>
>> Lots of excess brackets (see CodingStyle) - removing a few of the
>> excess ones would make it easier to read later.
>>
>> The later bits become a real mess of ifdefs - much not your fault, the
>> combination of your ifdefs and existing lack of design push it beyond
>> ugly and really want addressing.
>>
>>
>
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Re: [PATCH 02/14] ARM : SAMSUNG : Add RS485 support.

[Paul Schilling]

Sorry for the formatting mess on the previous email.  Lets try
this again.

I need an opinion on two issues before I resubmit the Samsung
RS-485 driver.

First of all the driver works.  I have tested it on a logic analyser
and I found that it switches from transmit to receive in token
mode exactly after 1 bit of idle time as long as interrupts are kept
enabled and nothing tries to wait or sleep inside of an interrupt.
I found 2 maybe 3 places where this occurs up to 22 milliseconds.

The opinion part...  I needed a timer to switch from transmit to
receive after the FIFO was empty.  I started by using the low
resolution timer using jiffies first.  I found that wasn't high enough
resolution, so I switched to the Linux HRT.  Currently I have both
versions that can be selected by conditional compile.  Should I
just remove the low resolution timer completely or leave it in.

Second, I have a chunk of code that if it could be made to work
could off load the receiving to DMA up to the last couple of bytes
then switch back to interrupts for the token byte.  Should I leave
that code in a #if 0 statement or should I just delete it.

Thanks,
Paul Schilling

> On Tue, Nov 1, 2011 at 9:57 AM, Paul Schilling
> <paul.s.schilling@gmail.com> wrote:
>> I am working on resubmitting this stuff right now.  I have 14 patches
>> that should be
>> broken into more like 20 patches.  Most of them are ARM S3C and
>> specifically S3C2416 patches.
>> I am working on a patch right now to fix a Atomic wait in the DMA
>> code.  That causes
>> 20 milliseconds of no interrupts whenever a sound is played on the samsung S3C
>> platform.
>>
>> The code below wasn't supposed to go out and I have patch that removes
>> that chunk
>> of code almost ready that just needs testing before I send it.
>>
>> On Tue, Nov 1, 2011 at 7:18 AM, Alan Cox <alan@linux.intel.com> wrote:
>>>> +config SAMSUNG_HAS_RS485
>>>> +     bool "Enable RS485 support for Samsung"
>>>> +     depends on SERIAL_SAMSUNG && (MACH_CONDOR2440 ||
>>>> MACH_CONDOR2416 || MACH_MINI2440)
>>>> +     default y if (MACH_CONDOR2440 || MACH_CONDOR2416)
>>>> +     default n if (MACH_MINI2440)
>>>
>>> There really needs to be more ARM thinking about doing this sort of
>>> stuff at runtime. If you can detect the board type at runtime then you
>>> need to be moving towards kicking board specifics out of the depends,
>>> and treating it as an "include support for this, if the board has it"
>>> so you can move towards less build time only configuration.
>>>
>>
>> The chunk of code that says FIXME is an optimization that could be
>> implemented to
>> decrease interrupts by using DMA until the last byte is ready to be
>> sent.  I have a new
>> patch that explains in a comment what the code is for.
>>
>>>> +/* FIXME */
>>>> +     #if 0
>>>> +     if (last_state != en) {
>>>> +
>>>
>>> So this doesn't look ready to submit either...
>>>
>>
>> I have a patch that I haven't sent yet that fixes the code formating
>> issues.  I need to compile and test it before I send it out.
>>
>>>
>>>> +             if ((utrstat & S3C2410_UTRSTAT_TXE) ? 1 : 0) {
>>>> +                     if (cfg->gpio_transmit_en > -1) {
>>>> +
>>>> gpio_set_value(cfg->gpio_transmit_en, 0);
>>>> +                     }
>>>
>>> Lots of excess brackets (see CodingStyle) - removing a few of the
>>> excess ones would make it easier to read later.
>>>
>>> The later bits become a real mess of ifdefs - much not your fault, the
>>> combination of your ifdefs and existing lack of design push it beyond
>>> ugly and really want addressing.
>>>
>>>
>>
>
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Re: [PATCH 02/14] ARM : SAMSUNG : Add RS485 support.

[Alan Cox]

> The opinion part...  I needed a timer to switch from transmit to
> receive after the FIFO was empty.  I started by using the low
> resolution timer using jiffies first.  I found that wasn't high enough
> resolution, so I switched to the Linux HRT.  Currently I have both
> versions that can be selected by conditional compile.  Should I
> just remove the low resolution timer completely or leave it in.

I would just remove the low res one. They should degrade to low res
timer equivalence anyway.

> Second, I have a chunk of code that if it could be made to work
> could off load the receiving to DMA up to the last couple of bytes
> then switch back to interrupts for the token byte.  Should I leave
> that code in a #if 0 statement or should I just delete it.

Is it something that you are likely to debug or someone is going to
debug shortly ?
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Re: [PATCH 02/14] ARM : SAMSUNG : Add RS485 support.

[Nicolas Ferre]

On 10/22/2011 05:46 AM, Paul Schilling :
> Add RS485 tranmit/recieve control line capabilities
> This RS485 driver uses two methodes to determine if the transmit
> should be disabled.

[..]

> This patch adds an additional variable to the serial RS-485 struct so
> that a program can change the terminate token value via the IOCTL.

[..]

> diff --git a/include/linux/serial.h b/include/linux/serial.h
> index ef91406..826b1c0 100644
> --- a/include/linux/serial.h
> +++ b/include/linux/serial.h
> @@ -211,9 +211,12 @@ struct serial_rs485 {
>  #define SER_RS485_RTS_ON_SEND		(1 << 1)
>  #define SER_RS485_RTS_AFTER_SEND	(1 << 2)
>  #define SER_RS485_RTS_BEFORE_SEND	(1 << 3)
> +#define SER_RS485_ALWAYS_LISTEN		(1 << 4)

This value is already in another patch (now in Linus' tree).

> +#define SER_RS485_TOGGLE_ON_TOKEN	(1 << 5)
>  	__u32	delay_rts_before_send;	/* Milliseconds */
>  	__u32	delay_rts_after_send;	/* Milliseconds */
> -	__u32	padding[5];		/* Memory is cheap, new structs
> +	__u32	toggle_token;			/* Token used to toggle to receive */

Do not forget to add this new value in the RS485 device tree bindings
[1] that appeared during this merge window. Once converted to device
tree, your platform may need to retrieve this value from it.

[1]: Documentation/devicetree/bindings/serial/rs485.txt

Best regards,
-- 
Nicolas Ferre