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include: uapi: serial: add support of rts delays in nanoseconds

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Add support of rs485 delay in nanoseconds.

With fast data rates (1Mbaut or more), 1ms become quite long. Users need
to be able to set shorter delays than 1 ms in order not to slow down the
channel unnecessarily. This enables faster communication channels without
changing the baudrate.

Signed-off-by: Erwan Le Ray <erwan.leray@foss.st.com>
Signed-off-by: Borut Seljak <borut.seljak@t-2.net>
Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Change-Id: I72cdf03197b7c3abfc1f2fa0c03e91b665461be1
This commit is contained in:
Erwan Le Ray
2020-04-12 19:06:20 +02:00
committed by Eric Fourmont
parent f2c236575f
commit 8fe0cd660f
2 changed files with 6 additions and 4 deletions
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4
drivers/tty/serial/serial_core.c
View File

@ -3464,10 +3464,10 @@ EXPORT_SYMBOL_GPL(uart_get_rs485_mode);
/* Compile-time assertions for serial_rs485 layout */
static_assert(offsetof(struct serial_rs485, padding) ==
(offsetof(struct serial_rs485, delay_rts_after_send) + sizeof(__u32)));
(offsetof(struct serial_rs485, delay_rts_after_send_ns) + sizeof(__u32)));
static_assert(offsetof(struct serial_rs485, padding1) ==
offsetof(struct serial_rs485, padding[1]));
static_assert((offsetof(struct serial_rs485, padding[4]) + sizeof(__u32)) ==
static_assert((offsetof(struct serial_rs485, padding[2]) + sizeof(__u32)) ==
sizeof(struct serial_rs485));
MODULE_DESCRIPTION("Serial driver core");

6
include/uapi/linux/serial.h
View File

@ -134,16 +134,18 @@ struct serial_rs485 {
__u32 delay_rts_before_send; /* Delay before send (milliseconds) */
__u32 delay_rts_after_send; /* Delay after send (milliseconds) */
__u32 delay_rts_before_send_ns; /* Delay before send (nanoseconds) */
__u32 delay_rts_after_send_ns; /* Delay after send (nanoseconds) */
/* The fields below are defined by flags */
union {
__u32 padding[5]; /* Memory is cheap, new structs are a pain */
__u32 padding[3]; /* Memory is cheap, new structs are a pain */
struct {
__u8 addr_recv;
__u8 addr_dest;
__u8 padding0[2];
__u32 padding1[4];
__u32 padding1[2];
};
};
};