Messages in this thread Patch in this message | | | Date | Mon, 18 Aug 2008 16:25:26 +0100 | From | Alan Cox <> | Subject | Re: [PATCH v1] 8250: add support for DTR/DSR hardware flow control |
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On Thu, 7 Aug 2008 14:54:05 +0200 "Tosoni" <jp.tosoni@acksys.fr> 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@redhat.com>
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@redhat.com> ---
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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