bd96e10071
The Linux kernel added a flood check for RX data recently in commit
496a4471b7c3 ("serial: imx: work-around for hardware RX flood"). This
check uses the wake bit in the UART status register 2. The wake bit
indicates that the receiver detected a start bit on the RX line. If the
kernel sees a number of RX interrupts without the wake bit being set, it
treats this as spurious data and resets the UART port. imx_serial does
never set the wake bit and triggers the kernel's flood check.
This patch adds support for the wake bit. wake is set when we receive a
new character (it's not set for break events). It seems that wake is
cleared by the kernel driver, the hardware does not have to clear it
automatically after data was read.
The wake bit can be configured as an interrupt source. Support this
mechanism as well.
Co-developed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
111 lines
3.9 KiB
C
111 lines
3.9 KiB
C
/*
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* Device model for i.MX UART
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*
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* Copyright (c) 2008 OKL
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* Originally Written by Hans Jiang
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* Copyright (c) 2011 NICTA Pty Ltd.
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* Updated by Jean-Christophe Dubois <jcd@tribudubois.net>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef IMX_SERIAL_H
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#define IMX_SERIAL_H
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#include "hw/sysbus.h"
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#include "chardev/char-fe.h"
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#include "qom/object.h"
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#define TYPE_IMX_SERIAL "imx.serial"
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OBJECT_DECLARE_SIMPLE_TYPE(IMXSerialState, IMX_SERIAL)
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#define URXD_CHARRDY (1<<15) /* character read is valid */
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#define URXD_ERR (1<<14) /* Character has error */
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#define URXD_FRMERR (1<<12) /* Character has frame error */
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#define URXD_BRK (1<<11) /* Break received */
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#define USR1_PARTYER (1<<15) /* Parity Error */
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#define USR1_RTSS (1<<14) /* RTS pin status */
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#define USR1_TRDY (1<<13) /* Tx ready */
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#define USR1_RTSD (1<<12) /* RTS delta: pin changed state */
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#define USR1_ESCF (1<<11) /* Escape sequence interrupt */
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#define USR1_FRAMERR (1<<10) /* Framing error */
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#define USR1_RRDY (1<<9) /* receiver ready */
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#define USR1_AGTIM (1<<8) /* Aging timer interrupt */
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#define USR1_DTRD (1<<7) /* DTR changed */
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#define USR1_RXDS (1<<6) /* Receiver is idle */
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#define USR1_AIRINT (1<<5) /* Aysnch IR interrupt */
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#define USR1_AWAKE (1<<4) /* Falling edge detected on RXd pin */
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#define USR2_ADET (1<<15) /* Autobaud complete */
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#define USR2_TXFE (1<<14) /* Transmit FIFO empty */
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#define USR2_DTRF (1<<13) /* DTR/DSR transition */
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#define USR2_IDLE (1<<12) /* UART has been idle for too long */
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#define USR2_ACST (1<<11) /* Autobaud counter stopped */
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#define USR2_RIDELT (1<<10) /* Ring Indicator delta */
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#define USR2_RIIN (1<<9) /* Ring Indicator Input */
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#define USR2_IRINT (1<<8) /* Serial Infrared Interrupt */
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#define USR2_WAKE (1<<7) /* Start bit detected */
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#define USR2_DCDDELT (1<<6) /* Data Carrier Detect delta */
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#define USR2_DCDIN (1<<5) /* Data Carrier Detect Input */
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#define USR2_RTSF (1<<4) /* RTS transition */
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#define USR2_TXDC (1<<3) /* Transmission complete */
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#define USR2_BRCD (1<<2) /* Break condition detected */
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#define USR2_ORE (1<<1) /* Overrun error */
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#define USR2_RDR (1<<0) /* Receive data ready */
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#define UCR1_TRDYEN (1<<13) /* Tx Ready Interrupt Enable */
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#define UCR1_RRDYEN (1<<9) /* Rx Ready Interrupt Enable */
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#define UCR1_TXMPTYEN (1<<6) /* Tx Empty Interrupt Enable */
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#define UCR1_UARTEN (1<<0) /* UART Enable */
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#define UCR2_TXEN (1<<2) /* Transmitter enable */
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#define UCR2_RXEN (1<<1) /* Receiver enable */
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#define UCR2_SRST (1<<0) /* Reset complete */
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#define UCR4_DREN BIT(0) /* Receive Data Ready interrupt enable */
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#define UCR4_TCEN BIT(3) /* TX complete interrupt enable */
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#define UCR4_WKEN BIT(7) /* WAKE interrupt enable */
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#define UTS1_TXEMPTY (1<<6)
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#define UTS1_RXEMPTY (1<<5)
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#define UTS1_TXFULL (1<<4)
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#define UTS1_RXFULL (1<<3)
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struct IMXSerialState {
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/*< private >*/
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SysBusDevice parent_obj;
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/*< public >*/
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MemoryRegion iomem;
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int32_t readbuff;
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uint32_t usr1;
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uint32_t usr2;
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uint32_t ucr1;
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uint32_t ucr2;
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uint32_t uts1;
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/*
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* The registers below are implemented just so that the
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* guest OS sees what it has written
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*/
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uint32_t onems;
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uint32_t ufcr;
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uint32_t ubmr;
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uint32_t ubrc;
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uint32_t ucr3;
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uint32_t ucr4;
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qemu_irq irq;
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CharBackend chr;
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};
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#endif
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