From: Samuel Thibault <samuel.thibault@ens-lyon.org>
Some Visiobraille braille terminals (TVB) need a peculiar serial flow
control:
- There is no flow control for the PC -> device way (yes, oddly enough)
- For the device -> PC way,
* RTS must be kept low, the device keeps CTS low as well.
* when the device wants to send data, it raises CTS. RTS must be
raised as well. Data can then pass, CTS and RTS are lowered.
We tried to implement that in user space, with ioctl(TIOCMBIS) & al, but
the responsiveness is too low: RTS is not raised soon enough, and the
device aborts transmission.
The patch defines a CTVB flag the same way CRTSCTS is defined, letting user
space choose whether to use it or not (better ideas for the name are
welcome). This makes the device work perfectly (even better than shipped
drivers for DOS).
rmk said:
I think if we're going to start accepting alternative flow control methods
into the kernel, we need to seriously think about how we're going to accept
them - lest the RS485 people come stomping at our door.
Rather than having a "CTVB" flow control mode separate from CRTSCTS, I
think we need CRTSCTS to be the master enable/disable, and a "flow control
personality" setting which selects between standard flow control, CTVB flow
control, and whatever else flow control. I think Alan pointed out that
there's a similar flow control method which uses RTS to request the remote
end to send data.
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/drivers/serial/serial_core.c | 44 +++++++++++++++------------------
25-akpm/include/asm-alpha/termbits.h | 1
25-akpm/include/asm-arm/termbits.h | 1
25-akpm/include/asm-arm26/termbits.h | 1
25-akpm/include/asm-cris/termbits.h | 4 ++-
25-akpm/include/asm-h8300/termbits.h | 1
25-akpm/include/asm-i386/termbits.h | 1
25-akpm/include/asm-ia64/termbits.h | 1
25-akpm/include/asm-m68k/termbits.h | 1
25-akpm/include/asm-mips/termbits.h | 1
25-akpm/include/asm-parisc/termbits.h | 1
25-akpm/include/asm-ppc/termbits.h | 1
25-akpm/include/asm-ppc64/termbits.h | 1
25-akpm/include/asm-s390/termbits.h | 1
25-akpm/include/asm-sh/termbits.h | 1
25-akpm/include/asm-sparc/termbits.h | 1
25-akpm/include/asm-sparc64/termbits.h | 1
25-akpm/include/asm-v850/termbits.h | 1
25-akpm/include/asm-x86_64/termbits.h | 1
25-akpm/include/linux/serial.h | 3 +-
25-akpm/include/linux/serial_core.h | 24 ++++++++++++++++++
25-akpm/include/linux/tty.h | 1
22 files changed, 68 insertions(+), 25 deletions(-)
diff -puN drivers/serial/serial_core.c~new-serial-flow-control drivers/serial/serial_core.c
--- 25/drivers/serial/serial_core.c~new-serial-flow-control 2004-11-15 20:02:15.975126984 -0800
+++ 25-akpm/drivers/serial/serial_core.c 2004-11-15 20:02:16.167097800 -0800
@@ -111,23 +111,6 @@ static void uart_tasklet_action(unsigned
tty_wakeup(state->info->tty);
}
-static inline void
-uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
-{
- unsigned long flags;
- unsigned int old;
-
- spin_lock_irqsave(&port->lock, flags);
- old = port->mctrl;
- port->mctrl = (old & ~clear) | set;
- if (old != port->mctrl)
- port->ops->set_mctrl(port, port->mctrl);
- spin_unlock_irqrestore(&port->lock, flags);
-}
-
-#define uart_set_mctrl(port,set) uart_update_mctrl(port,set,0)
-#define uart_clear_mctrl(port,clear) uart_update_mctrl(port,0,clear)
-
/*
* Startup the port. This will be called once per open. All calls
* will be serialised by the per-port semaphore.
@@ -178,8 +161,13 @@ static int uart_startup(struct uart_stat
* Setup the RTS and DTR signals once the
* port is open and ready to respond.
*/
- if (info->tty->termios->c_cflag & CBAUD)
- uart_set_mctrl(port, TIOCM_RTS | TIOCM_DTR);
+ if (info->tty->termios->c_cflag & CBAUD) {
+ uart_set_mctrl(port, TIOCM_DTR);
+ if (info->tty->termios->c_cflag & CTVB)
+ uart_clear_mctrl(port, TIOCM_RTS);
+ else
+ uart_set_mctrl(port, TIOCM_RTS);
+ }
}
info->flags |= UIF_INITIALIZED;
@@ -424,6 +412,11 @@ uart_change_speed(struct uart_state *sta
else
state->info->flags &= ~UIF_CTS_FLOW;
+ if (termios->c_cflag & CTVB)
+ state->info->flags |= UIF_TVB_FLOW;
+ else
+ state->info->flags &= ~UIF_TVB_FLOW;
+
if (termios->c_cflag & CLOCAL)
state->info->flags &= ~UIF_CHECK_CD;
else
@@ -1112,8 +1105,8 @@ static void uart_set_termios(struct tty_
/* Handle transition away from B0 status */
if (!(old_termios->c_cflag & CBAUD) && (cflag & CBAUD)) {
unsigned int mask = TIOCM_DTR;
- if (!(cflag & CRTSCTS) ||
- !test_bit(TTY_THROTTLED, &tty->flags))
+ if (!(cflag & CTVB) && (!(cflag & CRTSCTS) ||
+ !test_bit(TTY_THROTTLED, &tty->flags)))
mask |= TIOCM_RTS;
uart_set_mctrl(state->port, mask);
}
@@ -1350,8 +1343,13 @@ static void uart_update_termios(struct u
/*
* And finally enable the RTS and DTR signals.
*/
- if (tty->termios->c_cflag & CBAUD)
- uart_set_mctrl(port, TIOCM_DTR | TIOCM_RTS);
+ if (tty->termios->c_cflag & CBAUD) {
+ uart_set_mctrl(port, TIOCM_DTR);
+ if (tty->termios->c_cflag & CTVB)
+ uart_clear_mctrl(port,TIOCM_RTS);
+ else
+ uart_set_mctrl(port,TIOCM_RTS);
+ }
}
}
diff -puN include/asm-alpha/termbits.h~new-serial-flow-control include/asm-alpha/termbits.h
--- 25/include/asm-alpha/termbits.h~new-serial-flow-control 2004-11-15 20:02:15.976126832 -0800
+++ 25-akpm/include/asm-alpha/termbits.h 2004-11-15 20:02:16.168097648 -0800
@@ -148,6 +148,7 @@ struct termios {
#define HUPCL 00040000
#define CLOCAL 00100000
+#define CTVB 004000000000 /* VisioBraille Terminal flow control */
#define CRTSCTS 020000000000 /* flow control */
/* c_lflag bits */
diff -puN include/asm-arm26/termbits.h~new-serial-flow-control include/asm-arm26/termbits.h
--- 25/include/asm-arm26/termbits.h~new-serial-flow-control 2004-11-15 20:02:15.978126528 -0800
+++ 25-akpm/include/asm-arm26/termbits.h 2004-11-15 20:02:16.168097648 -0800
@@ -132,6 +132,7 @@ struct termios {
#define B3500000 0010016
#define B4000000 0010017
#define CIBAUD 002003600000 /* input baud rate (not used) */
+#define CTVB 004000000000 /* VisioBraille Terminal flow control */
#define CMSPAR 010000000000 /* mark or space (stick) parity */
#define CRTSCTS 020000000000 /* flow control */
diff -puN include/asm-arm/termbits.h~new-serial-flow-control include/asm-arm/termbits.h
--- 25/include/asm-arm/termbits.h~new-serial-flow-control 2004-11-15 20:02:15.980126224 -0800
+++ 25-akpm/include/asm-arm/termbits.h 2004-11-15 20:02:16.169097496 -0800
@@ -132,6 +132,7 @@ struct termios {
#define B3500000 0010016
#define B4000000 0010017
#define CIBAUD 002003600000 /* input baud rate (not used) */
+#define CTVB 004000000000 /* VisioBraille Terminal flow control */
#define CMSPAR 010000000000 /* mark or space (stick) parity */
#define CRTSCTS 020000000000 /* flow control */
diff -puN include/asm-cris/termbits.h~new-serial-flow-control include/asm-cris/termbits.h
--- 25/include/asm-cris/termbits.h~new-serial-flow-control 2004-11-15 20:02:16.136102512 -0800
+++ 25-akpm/include/asm-cris/termbits.h 2004-11-15 20:02:16.169097496 -0800
@@ -108,9 +108,10 @@ struct termios {
* 10 987 654 321 098 765 432 109 876 543 210
* | || || CIBAUD, IBSHIFT=16
* ibaud
+ * |CTVB
* |CMSPAR
* | CRTSCTS
- * x x xxx xxx x x xx Free bits
+ * x xxx xxx x x xx Free bits
*/
#define CBAUD 0010017
@@ -159,6 +160,7 @@ struct termios {
* shifted left IBSHIFT bits.
*/
#define IBSHIFT 16
+#define CTVB 004000000000 /* VisioBraille Terminal flow control */
#define CMSPAR 010000000000 /* mark or space (stick) parity - PARODD=space*/
#define CRTSCTS 020000000000 /* flow control */
diff -puN include/asm-h8300/termbits.h~new-serial-flow-control include/asm-h8300/termbits.h
--- 25/include/asm-h8300/termbits.h~new-serial-flow-control 2004-11-15 20:02:16.138102208 -0800
+++ 25-akpm/include/asm-h8300/termbits.h 2004-11-15 20:02:16.169097496 -0800
@@ -135,6 +135,7 @@ struct termios {
#define B3500000 0010016
#define B4000000 0010017
#define CIBAUD 002003600000 /* input baud rate (not used) */
+#define CTVB 004000000000 /* VisioBraille Terminal flow control */
#define CMSPAR 010000000000 /* mark or space (stick) parity */
#define CRTSCTS 020000000000 /* flow control */
diff -puN include/asm-i386/termbits.h~new-serial-flow-control include/asm-i386/termbits.h
--- 25/include/asm-i386/termbits.h~new-serial-flow-control 2004-11-15 20:02:16.140101904 -0800
+++ 25-akpm/include/asm-i386/termbits.h 2004-11-15 20:02:16.170097344 -0800
@@ -134,6 +134,7 @@ struct termios {
#define B3500000 0010016
#define B4000000 0010017
#define CIBAUD 002003600000 /* input baud rate (not used) */
+#define CTVB 004000000000 /* VisioBraille Terminal flow control */
#define CMSPAR 010000000000 /* mark or space (stick) parity */
#define CRTSCTS 020000000000 /* flow control */
diff -puN include/asm-ia64/termbits.h~new-serial-flow-control include/asm-ia64/termbits.h
--- 25/include/asm-ia64/termbits.h~new-serial-flow-control 2004-11-15 20:02:16.141101752 -0800
+++ 25-akpm/include/asm-ia64/termbits.h 2004-11-15 20:02:16.170097344 -0800
@@ -143,6 +143,7 @@ struct termios {
#define B3500000 0010016
#define B4000000 0010017
#define CIBAUD 002003600000 /* input baud rate (not used) */
+#define CTVB 004000000000 /* VisioBraille Terminal flow control */
#define CMSPAR 010000000000 /* mark or space (stick) parity */
#define CRTSCTS 020000000000 /* flow control */
diff -puN include/asm-m68k/termbits.h~new-serial-flow-control include/asm-m68k/termbits.h
--- 25/include/asm-m68k/termbits.h~new-serial-flow-control 2004-11-15 20:02:16.143101448 -0800
+++ 25-akpm/include/asm-m68k/termbits.h 2004-11-15 20:02:16.171097192 -0800
@@ -135,6 +135,7 @@ struct termios {
#define B3500000 0010016
#define B4000000 0010017
#define CIBAUD 002003600000 /* input baud rate (not used) */
+#define CTVB 004000000000 /* VisioBraille Terminal flow control */
#define CMSPAR 010000000000 /* mark or space (stick) parity */
#define CRTSCTS 020000000000 /* flow control */
diff -puN include/asm-mips/termbits.h~new-serial-flow-control include/asm-mips/termbits.h
--- 25/include/asm-mips/termbits.h~new-serial-flow-control 2004-11-15 20:02:16.144101296 -0800
+++ 25-akpm/include/asm-mips/termbits.h 2004-11-15 20:02:16.171097192 -0800
@@ -164,6 +164,7 @@ struct termios {
#define B3500000 0010016
#define B4000000 0010017
#define CIBAUD 002003600000 /* input baud rate (not used) */
+#define CTVB 004000000000 /* VisioBraille Terminal flow control */
#define CMSPAR 010000000000 /* mark or space (stick) parity */
#define CRTSCTS 020000000000 /* flow control */
diff -puN include/asm-parisc/termbits.h~new-serial-flow-control include/asm-parisc/termbits.h
--- 25/include/asm-parisc/termbits.h~new-serial-flow-control 2004-11-15 20:02:16.146100992 -0800
+++ 25-akpm/include/asm-parisc/termbits.h 2004-11-15 20:02:16.171097192 -0800
@@ -135,6 +135,7 @@ struct termios {
#define B3500000 0010016
#define B4000000 0010017
#define CIBAUD 002003600000 /* input baud rate (not used) */
+#define CTVB 004000000000 /* VisioBraille Terminal flow control */
#define CMSPAR 010000000000 /* mark or space (stick) parity */
#define CRTSCTS 020000000000 /* flow control */
diff -puN include/asm-ppc64/termbits.h~new-serial-flow-control include/asm-ppc64/termbits.h
--- 25/include/asm-ppc64/termbits.h~new-serial-flow-control 2004-11-15 20:02:16.148100688 -0800
+++ 25-akpm/include/asm-ppc64/termbits.h 2004-11-15 20:02:16.172097040 -0800
@@ -155,6 +155,7 @@ struct termios {
#define HUPCL 00040000
#define CLOCAL 00100000
+#define CTVB 004000000000 /* VisioBraille Terminal flow control */
#define CRTSCTS 020000000000 /* flow control */
/* c_lflag bits */
diff -puN include/asm-ppc/termbits.h~new-serial-flow-control include/asm-ppc/termbits.h
--- 25/include/asm-ppc/termbits.h~new-serial-flow-control 2004-11-15 20:02:16.149100536 -0800
+++ 25-akpm/include/asm-ppc/termbits.h 2004-11-15 20:02:16.172097040 -0800
@@ -147,6 +147,7 @@ struct termios {
#define HUPCL 00040000
#define CLOCAL 00100000
+#define CTVB 004000000000 /* VisioBraille Terminal flow control */
#define CRTSCTS 020000000000 /* flow control */
/* c_lflag bits */
diff -puN include/asm-s390/termbits.h~new-serial-flow-control include/asm-s390/termbits.h
--- 25/include/asm-s390/termbits.h~new-serial-flow-control 2004-11-15 20:02:16.151100232 -0800
+++ 25-akpm/include/asm-s390/termbits.h 2004-11-15 20:02:16.173096888 -0800
@@ -142,6 +142,7 @@ struct termios {
#define B3500000 0010016
#define B4000000 0010017
#define CIBAUD 002003600000 /* input baud rate (not used) */
+#define CTVB 004000000000 /* VisioBraille Terminal flow control */
#define CMSPAR 010000000000 /* mark or space (stick) parity */
#define CRTSCTS 020000000000 /* flow control */
diff -puN include/asm-sh/termbits.h~new-serial-flow-control include/asm-sh/termbits.h
--- 25/include/asm-sh/termbits.h~new-serial-flow-control 2004-11-15 20:02:16.152100080 -0800
+++ 25-akpm/include/asm-sh/termbits.h 2004-11-15 20:02:16.173096888 -0800
@@ -134,6 +134,7 @@ struct termios {
#define B3500000 0010016
#define B4000000 0010017
#define CIBAUD 002003600000 /* input baud rate (not used) */
+#define CTVB 004000000000 /* VisioBraille Terminal flow control */
#define CMSPAR 010000000000 /* mark or space (stick) parity */
#define CRTSCTS 020000000000 /* flow control */
diff -puN include/asm-sparc64/termbits.h~new-serial-flow-control include/asm-sparc64/termbits.h
--- 25/include/asm-sparc64/termbits.h~new-serial-flow-control 2004-11-15 20:02:16.154099776 -0800
+++ 25-akpm/include/asm-sparc64/termbits.h 2004-11-15 20:02:16.174096736 -0800
@@ -175,6 +175,7 @@ struct termios {
#define B3500000 0x00001012
#define B4000000 0x00001013 */
#define CIBAUD 0x100f0000 /* input baud rate (not used) */
+#define CTVB 0x20000000 /* VisioBraille Terminal flow control */
#define CMSPAR 0x40000000 /* mark or space (stick) parity */
#define CRTSCTS 0x80000000 /* flow control */
diff -puN include/asm-sparc/termbits.h~new-serial-flow-control include/asm-sparc/termbits.h
--- 25/include/asm-sparc/termbits.h~new-serial-flow-control 2004-11-15 20:02:16.155099624 -0800
+++ 25-akpm/include/asm-sparc/termbits.h 2004-11-15 20:02:16.174096736 -0800
@@ -174,6 +174,7 @@ struct termios {
#define B3500000 0x00001012
#define B4000000 0x00001013 */
#define CIBAUD 0x100f0000 /* input baud rate (not used) */
+#define CTVB 0x20000000 /* VisioBraille Terminal flow control */
#define CMSPAR 0x40000000 /* mark or space (stick) parity */
#define CRTSCTS 0x80000000 /* flow control */
diff -puN include/asm-v850/termbits.h~new-serial-flow-control include/asm-v850/termbits.h
--- 25/include/asm-v850/termbits.h~new-serial-flow-control 2004-11-15 20:02:16.157099320 -0800
+++ 25-akpm/include/asm-v850/termbits.h 2004-11-15 20:02:16.174096736 -0800
@@ -135,6 +135,7 @@ struct termios {
#define B3500000 0010016
#define B4000000 0010017
#define CIBAUD 002003600000 /* input baud rate (not used) */
+#define CTVB 004000000000 /* VisioBraille Terminal flow control */
#define CMSPAR 010000000000 /* mark or space (stick) parity */
#define CRTSCTS 020000000000 /* flow control */
diff -puN include/asm-x86_64/termbits.h~new-serial-flow-control include/asm-x86_64/termbits.h
--- 25/include/asm-x86_64/termbits.h~new-serial-flow-control 2004-11-15 20:02:16.158099168 -0800
+++ 25-akpm/include/asm-x86_64/termbits.h 2004-11-15 20:02:16.175096584 -0800
@@ -134,6 +134,7 @@ struct termios {
#define B3500000 0010016
#define B4000000 0010017
#define CIBAUD 002003600000 /* input baud rate (not used) */
+#define CTVB 004000000000 /* VisioBraille Terminal flow control */
#define CMSPAR 010000000000 /* mark or space (stick) parity */
#define CRTSCTS 020000000000 /* flow control */
diff -puN include/linux/serial_core.h~new-serial-flow-control include/linux/serial_core.h
--- 25/include/linux/serial_core.h~new-serial-flow-control 2004-11-15 20:02:16.159099016 -0800
+++ 25-akpm/include/linux/serial_core.h 2004-11-15 20:02:16.176096432 -0800
@@ -273,6 +273,7 @@ struct uart_info {
*/
#define UIF_CHECK_CD (1 << 25)
#define UIF_CTS_FLOW (1 << 26)
+#define UIF_TVB_FLOW (1 << 21)
#define UIF_NORMAL_ACTIVE (1 << 29)
#define UIF_INITIALIZED (1 << 31)
@@ -381,6 +382,23 @@ uart_handle_sysrq_char(struct uart_port
#define uart_handle_sysrq_char(port,ch,regs) (0)
#endif
+static inline void
+uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
+{
+ unsigned long flags;
+ unsigned int old;
+
+ spin_lock_irqsave(&port->lock, flags);
+ old = port->mctrl;
+ port->mctrl = (old & ~clear) | set;
+ if (old != port->mctrl)
+ port->ops->set_mctrl(port, port->mctrl);
+ spin_unlock_irqrestore(&port->lock, flags);
+}
+
+#define uart_set_mctrl(port,set) uart_update_mctrl(port,set,0)
+#define uart_clear_mctrl(port,clear) uart_update_mctrl(port,0,clear)
+
/*
* We do the SysRQ and SAK checking like this...
*/
@@ -452,6 +470,11 @@ uart_handle_cts_change(struct uart_port
port->ops->stop_tx(port, 0);
}
}
+ } else if (info->flags & UIF_TVB_FLOW) {
+ if (status)
+ uart_set_mctrl(port, TIOCM_RTS);
+ else
+ uart_clear_mctrl(port, TIOCM_RTS);
}
}
@@ -460,6 +483,7 @@ uart_handle_cts_change(struct uart_port
*/
#define UART_ENABLE_MS(port,cflag) ((port)->flags & UPF_HARDPPS_CD || \
(cflag) & CRTSCTS || \
+ (cflag) & CTVB || \
!((cflag) & CLOCAL))
#endif
diff -puN include/linux/serial.h~new-serial-flow-control include/linux/serial.h
--- 25/include/linux/serial.h~new-serial-flow-control 2004-11-15 20:02:16.161098712 -0800
+++ 25-akpm/include/linux/serial.h 2004-11-15 20:02:16.177096280 -0800
@@ -141,7 +141,8 @@ struct serial_uart_config {
#define ASYNC_CONS_FLOW 0x00800000 /* flow control for console */
#define ASYNC_BOOT_ONLYMCA 0x00400000 /* Probe only if MCA bus */
-#define ASYNC_INTERNAL_FLAGS 0xFFC00000 /* Internal flags */
+#define ASYNC_TVB_FLOW 0x00200000 /* Do VisioBraille flow control */
+#define ASYNC_INTERNAL_FLAGS 0xFFE00000 /* Internal flags */
/*
* Multiport serial configuration structure --- external structure
diff -puN include/linux/tty.h~new-serial-flow-control include/linux/tty.h
--- 25/include/linux/tty.h~new-serial-flow-control 2004-11-15 20:02:16.162098560 -0800
+++ 25-akpm/include/linux/tty.h 2004-11-15 20:02:16.177096280 -0800
@@ -210,6 +210,7 @@ struct tty_flip_buffer {
#define C_CLOCAL(tty) _C_FLAG((tty),CLOCAL)
#define C_CIBAUD(tty) _C_FLAG((tty),CIBAUD)
#define C_CRTSCTS(tty) _C_FLAG((tty),CRTSCTS)
+#define C_TVB(tty) _C_FLAG((tty),CTVB)
#define L_ISIG(tty) _L_FLAG((tty),ISIG)
#define L_ICANON(tty) _L_FLAG((tty),ICANON)
_