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Jim Chen ( 14/06/2011 Hytec Electronics Ltd.

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Presentation on theme: "Jim Chen ( 14/06/2011 Hytec Electronics Ltd."— Presentation transcript:

1 Jim Chen ( jim.chen@hytec-electronics.co.uk )jim.chen@hytec-electronics.co.uk 14/06/2011 Hytec Electronics Ltd

2 14/06/2011

3 Hytec Electronics Ltd

4 14/06/2011 Hytec Electronics Ltd Devices ProcessorUART Other Devices PCI/PCIe/VME BUS RS232 RS485 Devices UART Tx Rx Baud rate Data bit Start/stop bit Parity check Flow control Settings

5 14/06/2011 Hytec Electronics Ltd User App EPICS Char Driver TTY Core Line Discipline Device Driver Devices ProcessorUART Other Devices PCI/PCIe/VME BUS RS232 RS485 Devices UART Console minicom ttyS0/ttyS1 KernelDevice Driver

6 Set up serial port in the simplest way – baud rate, data bit, stop bit No parity check, no flow control, no echo etc. Sending data via Tx. Receiving data via Rx. 14/06/2011 Hytec Electronics Ltd Manage modem – CTS, DSR, DTR, RTS, CD, RI etc, etc. Manage flow control and handshake. Manage special characters etc. Majority of serial users – sending/receiving data over 3/2/4 wires Options (most apps don’t)

7 14/06/2011 Hytec Electronics Ltd User App Char Driver TTY Core Line Discipline TTY Driver UART/Hardware Kernel

8 A glance at TTY device driver 14/06/2011 Hytec Electronics Ltd static struct tty_operations serial_ops = {.open = my_open,.close = my_close,.write = my_write,.write_room = my_write_room,.set_termios = my_set_termios,.ioctl = my_ioctl,.put_char = my_put_char,.flush_chars = my_flush_chars,.wait_until_sent = my_wait_until_sent,.chars_in_buffer = my_chars_in_buffer,.throttle = my_throttle,.unthrottle = my_unthrottle,.stop = my_stop,.start = my_start,.hangup = my_hangup,.break_ctl = my_break_ctl,.set_ldisc = my_set_ldisc,.send_xchar = my_send_xcahr, }; Operations

9 14/06/2011 Hytec Electronics Ltd

10 14/06/2011 Hytec Electronics Ltd User App Char Driver TTY Core Line Discipline Serial Core UART/Hardware UART Driver Kernel

11 14/06/2011 Hytec Electronics Ltd static struct uart_ops ioc9010_uart_pops = {.tx_empty = ioc9010_tx_empty,.set_mctrl = ioc9010_set_mctrl,.get_mctrl = ioc9010_get_mctrl,.stop_tx = ioc9010_stop_tx,.start_tx = ioc9010_start_tx,.stop_rx = ioc9010_stop_rx,.enable_ms = ioc9010_enable_ms,.break_ctl = ioc9010_break_ctl,.startup = ioc9010_startup,.shutdown = ioc9010_shutdown,.set_termios = ioc9010_set_termios,.type = ioc9010_type,.release_port = ioc9010_release_port,.request_port = ioc9010_request_port,.config_port = ioc9010_config_port,.verify_port = ioc9010_verify_port, }; Operations

12 14/06/2011 Hytec Electronics Ltd static struct uart_ops ioc9010_uart_pops = {.tx_empty = ioc9010_tx_empty,check transmt FIFO empty.set_mctrl = ioc9010_set_mctrl,set modem control lines, RTS, DTR etc.get_mctrl = ioc9010_get_mctrl,get modem control status, CTS, DCD, DSR RI etc.stop_tx = ioc9010_stop_tx,stop transmitting.start_tx = ioc9010_start_tx,enable transmitting.stop_rx = ioc9010_stop_rx,stop receiving, stop receive interrupt.enable_ms = ioc9010_enable_ms,set modem timer.break_ctl = ioc9010_break_ctl,control the transmission of a break signal.startup = ioc9010_startup,initialise port, register and enable interrupt.shutdown = ioc9010_shutdown,stop using port. Disable and free interrupt resources.set_termios = ioc9010_set_termios,set line pararmeters: baud rate, data bit, stop bit etc.type = ioc9010_type,return the string of the port device.release_port = ioc9010_release_port,release memory and IO region used by the port.request_port = ioc9010_request_port,request memory and IO region.config_port = ioc9010_config_port,perform any auto configuration steps.verify_port = ioc9010_verify_port,verify the port info is suitable for this port type };

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14 14/06/2011 Hytec Electronics Ltd

15 14/06/2011 Hytec Electronics Ltd

16 14/06/2011 Hytec Electronics Ltd

17 14/06/2011 Hytec Electronics Ltd

18 14/06/2011 Hytec Electronics Ltd /* Enable interrupts */

19 14/06/2011 Hytec Electronics Ltd /* Enable interrupts */

20 14/06/2011 Hytec Electronics Ltd /* Enable interrupts */

21 14/06/2011 Hytec Electronics Ltd /* Enable interrupts */

22 14/06/2011 Hytec Electronics Ltd /* Enable interrupts */

23 14/06/2011 Hytec Electronics Ltd irqreturn_t ioc9010_isr(int irq, void *dev_id, struct pt_regs *regs) { struct ioc9010_uart_port *ioc9010 = (struct ioc9010_uart_port *)dev_id; spin_lock(&ioc9010->port.lock);...... Hy85156_INTReason(ioc9010, &port, &reason); if ((reason & INTERRUPT_REASON_RXRDY) || ((reason & INTERRUPT_REASON_LSR) && (reason & INTERRUPT_REASON_LSR_RX_BREAK))) ioc9010_rx_chars(ioc9010); /* Byte or break signal received */ if (reason & INTERRUPT_REASON_TXRDY) ioc9010_tx_chars(ioc9010); /* TX holding register empty - transmit a byte if there is */ Hy85156_ResetInterrupt(ioc9010, ioc9010->portNo, reason); spin_unlock(&ioc9010->port.lock); return IRQ_HANDLED; }

24 14/06/2011 Hytec Electronics Ltd /* Enable interrupts */

25 14/06/2011 Hytec Electronics Ltd /* Enable interrupts */

26 14/06/2011 Hytec Electronics Ltd

27 14/06/2011 Hytec Electronics Ltd

28 Linux Device Driver, 3 rd edition 2005 (a bit obsolete) Low Level Serial API http://rhkernel.org/RHEL6+2.6.32-19.el6/Documentation/serial/driver The Serial Driver Layer http://www.linuxjournal.com/article/6331http://www.linuxjournal.com/article/6331 TTY flip buffer SMP changes http://lwn.net/Articles/105770/ Linux: tty Cleanup http://kerneltrap.org/node/5473http://kerneltrap.org/node/5473 API changes in the 2.6 kernel series http://lwn.net/Articles/2.6-kernel-api/, http://lwn.net/Articles/183225/http://lwn.net/Articles/2.6-kernel-api/http://lwn.net/Articles/183225/ The TTY demystified http://www.linusakesson.net/programming/tty/index.php 14/06/2011 Hytec Electronics Ltd

29 14/06/2011 Hytec Electronics Ltd Well Jim, it looks as clear as mud to me!

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