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SERIAL: core: add hardware assisted s/w flow control support
Ports which are capable of handling s/w flow control in hardware to know when the s/w flow control termios settings are changed. Add a flag to allow the low level serial drivers to indicate that they support this, and these changes should be propagated to them. Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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2 changed files with 16 additions and 2 deletions
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@ -1213,7 +1213,19 @@ static void uart_set_termios(struct tty_struct *tty,
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struct uart_port *uport = state->uart_port;
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unsigned long flags;
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unsigned int cflag = tty->termios.c_cflag;
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unsigned int iflag_mask = IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK;
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bool sw_changed = false;
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/*
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* Drivers doing software flow control also need to know
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* about changes to these input settings.
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*/
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if (uport->flags & UPF_SOFT_FLOW) {
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iflag_mask |= IXANY|IXON|IXOFF;
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sw_changed =
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tty->termios.c_cc[VSTART] != old_termios->c_cc[VSTART] ||
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tty->termios.c_cc[VSTOP] != old_termios->c_cc[VSTOP];
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}
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/*
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* These are the bits that are used to setup various
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@ -1221,11 +1233,11 @@ static void uart_set_termios(struct tty_struct *tty,
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* bits in c_cflag; c_[io]speed will always be set
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* appropriately by set_termios() in tty_ioctl.c
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*/
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#define RELEVANT_IFLAG(iflag) ((iflag) & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))
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if ((cflag ^ old_termios->c_cflag) == 0 &&
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tty->termios.c_ospeed == old_termios->c_ospeed &&
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tty->termios.c_ispeed == old_termios->c_ispeed &&
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RELEVANT_IFLAG(tty->termios.c_iflag ^ old_termios->c_iflag) == 0) {
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((tty->termios.c_iflag ^ old_termios->c_iflag) & iflag_mask) == 0 &&
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!sw_changed) {
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return;
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}
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@ -163,6 +163,8 @@ struct uart_port {
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#define UPF_BUGGY_UART ((__force upf_t) (1 << 14))
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#define UPF_NO_TXEN_TEST ((__force upf_t) (1 << 15))
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#define UPF_MAGIC_MULTIPLIER ((__force upf_t) (1 << 16))
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/* Port has hardware-assisted s/w flow control */
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#define UPF_SOFT_FLOW ((__force upf_t) (1 << 22))
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#define UPF_CONS_FLOW ((__force upf_t) (1 << 23))
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#define UPF_SHARE_IRQ ((__force upf_t) (1 << 24))
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#define UPF_EXAR_EFR ((__force upf_t) (1 << 25))
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