On Thu, 7 Aug 2008 14:54:05 +0200
"Tosoni" <jp.tosoni@xxxxxxxxx> wrote:
> About a RS485 ioctl: could you consider the attached files which are already
> in the Linux kernel (in include/asm-cris).
> They define a TIOCSERSETRS485 (ioctl.h), and the data structure (rs485.h)
> with allows to specify timings. Sounds just like what we want ?
I had a deeper look at this for RS485 and the answer is "sort of". I've
reworked the structure to keep it the same size irrespective of 32/64bit
systems, and to make stuff flags that can be, plus add some extra u32
words in case we need to (.. when we need to ;)) add stuff later.
Comments, thoughts - will this do what people in the RS485 world need ?
Alan
--------------
tty: Cris has a nice RS485 ioctl so we should steal it
From: Alan Cox <alan@xxxxxxxxxx>
JP Tosoni observed:
"About a RS485 ioctl: could you consider the attached files which are
already in the Linux kernel (in include/asm-cris). They define a
TIOCSERSETRS485 (ioctl.h), and the data structure (rs485.h)
with allows to specify timings. Sounds just like what we want ?"
and he's right: sort of. Rework the structure to use flag bits and make the
time delay a fixed sized field so we don't get 32/64bit problems. Add the ioctls
to x86 so that people know what to add to their platform of choice.
Signed-off-by: Alan Cox <alan@xxxxxxxxxx>
---
include/asm-x86/ioctls.h | 2 ++
include/linux/serial.h | 16 ++++++++++++++++
2 files changed, 18 insertions(+), 0 deletions(-)
diff --git a/include/asm-x86/ioctls.h b/include/asm-x86/ioctls.h
index c0c338b..2cd4775 100644
--- a/include/asm-x86/ioctls.h
+++ b/include/asm-x86/ioctls.h
@@ -51,6 +51,8 @@
#define TCSETS2 _IOW('T', 0x2B, struct termios2)
#define TCSETSW2 _IOW('T', 0x2C, struct termios2)
#define TCSETSF2 _IOW('T', 0x2D, struct termios2)
+#define TIOCGRS485 0x542E
+#define TIOCSRS485 0x542F
#define TIOCGPTN _IOR('T', 0x30, unsigned int)
/* Get Pty Number (of pty-mux device) */
#define TIOCSPTLCK _IOW('T', 0x31, int) /* Lock/unlock Pty */
diff --git a/include/linux/serial.h b/include/linux/serial.h
index deb7143..1ea8d92 100644
--- a/include/linux/serial.h
+++ b/include/linux/serial.h
@@ -173,6 +173,22 @@ struct serial_icounter_struct {
int reserved[9];
};
+/*
+ * Serial interface for controlling RS485 settings on chips with suitable
+ * support. Set with TIOCSRS485 and get with TIOCGRS485 if supported by your
+ * platform. The set function returns the new state, with any unsupported bits
+ * reverted appropriately.
+ */
+
+struct serial_rs485 {
+ __u32 flags; /* RS485 feature flags */
+#define SER_RS485_ENABLED (1 << 0)
+#define SER_RS485_RTS_ON_SEND (1 << 1)
+#define SER_RS485_RTS_AFTER_SEND (1 << 2)
+ __u32 delay_rts_before_send; /* Milliseconds */
+ __u32 padding[6]; /* Memory is cheap, new structs
+ are a royal PITA .. */
+};
#ifdef __KERNEL__
#include <linux/compiler.h>
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