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62 lines
1.9 KiB
Diff
62 lines
1.9 KiB
Diff
From a3749ee48539fa832b1832cdcae26d34e5d20f00 Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.org>
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Date: Fri, 24 Jan 2020 11:38:28 +0000
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Subject: [PATCH] tty: amba-pl011: Add un/throttle support
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The PL011 driver lacks throttle and unthrottle methods. As a result,
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sending more data to the Pi than it can immediately sink while CRTSCTS
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is enabled causes a NULL pointer to be followed.
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Add a throttle handler that disables the RX interrupts, and an
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unthrottle handler that reenables them.
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Signed-off-by: Phil Elwell <phil@raspberrypi.org>
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---
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drivers/tty/serial/amba-pl011.c | 28 ++++++++++++++++++++++++++++
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1 file changed, 28 insertions(+)
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--- a/drivers/tty/serial/amba-pl011.c
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+++ b/drivers/tty/serial/amba-pl011.c
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@@ -1323,6 +1323,32 @@ static void pl011_start_tx(struct uart_p
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pl011_start_tx_pio(uap);
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}
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+static void pl011_throttle(struct uart_port *port)
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+{
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+ struct uart_amba_port *uap =
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+ container_of(port, struct uart_amba_port, port);
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+ unsigned long flags;
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+
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+ spin_lock_irqsave(&uap->port.lock, flags);
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+ uap->im &= ~(UART011_RTIM | UART011_RXIM);
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+ pl011_write(uap->im, uap, REG_IMSC);
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+ spin_unlock_irqrestore(&uap->port.lock, flags);
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+}
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+
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+static void pl011_unthrottle(struct uart_port *port)
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+{
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+ struct uart_amba_port *uap =
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+ container_of(port, struct uart_amba_port, port);
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+ unsigned long flags;
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+
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+ spin_lock_irqsave(&uap->port.lock, flags);
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+ uap->im |= UART011_RTIM;
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+ if (!pl011_dma_rx_running(uap))
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+ uap->im |= UART011_RXIM;
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+ pl011_write(uap->im, uap, REG_IMSC);
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+ spin_unlock_irqrestore(&uap->port.lock, flags);
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+}
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+
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static void pl011_stop_rx(struct uart_port *port)
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{
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struct uart_amba_port *uap =
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@@ -2164,6 +2190,8 @@ static const struct uart_ops amba_pl011_
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.stop_tx = pl011_stop_tx,
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.start_tx = pl011_start_tx,
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.stop_rx = pl011_stop_rx,
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+ .throttle = pl011_throttle,
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+ .unthrottle = pl011_unthrottle,
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.enable_ms = pl011_enable_ms,
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.break_ctl = pl011_break_ctl,
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.startup = pl011_startup,
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