/* * soclib_tty.c - soclib tty driver definition. * * Author Alain Greiner (2016) * * Copyright (c) UPMC Sorbonne Universites * * This file is part of ALMOS-MKH. * * ALMOS-MKH is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by * the Free Software Foundation; version 2.0 of the License. * * ALMOS-MKH is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with ALMOS-kernel; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ #include #include #include /**************************************************************************************** * This driver supports the vci_tty_tsar component. * It implements the generic TXT device API: * - transfer one single character from TTY to command "buffer" if to_mem is non-zero. * - transfer "count" characters from command "buffer" to TTY if "to_mem is zero. ***************************************************************************************/ /**************************************************************************************** * SOCLIB_TTY registers offsets ***************************************************************************************/ #define TTY_WRITE 0 #define TTY_STATUS 1 #define TTY_READ 2 #define TTY_RX_IRQ_ENABLE 3 #define TTY_TX_IRQ_ENABLE 4 #define TTY_SPAN 8 // number of registers per channel /**************************************************************************************** * masks for TTY_STATUS_REG ***************************************************************************************/ #define TTY_STATUS_RX_FULL 1 // TTY_READ_REG full if 1 #define TTY_STATUS_TX_FULL 2 // TTY_WRITE_REG full if 1 /**************************************************************************************** * This function masks both the TTY_RX and TTY_TX IRQs. * These IRQs are unmasked by the soclib_tty_cmd() function. **************************************************************************************** * @ chdev : pointer on the TXT chdev descriptor. ***************************************************************************************/ void soclib_tty_init( chdev_t * chdev ); /**************************************************************************************** * This function implements both the TXT_READ & TXT_WRITE commands registered in the * client thread descriptor (in the txt_cmd field), even if ALMOS-MKH defines two * different chdevs (and consequently two diffeerent server threads) for the RX and TX * directions. The client thread is identified by the argument. * Depending on the command type, it unmasks the relevant TTY_RX / TTY_TX IRQ, * and blocks the TXT device server thread on the THREAD_BLOCKED_DEV_ISR, as the data * transfer is done by the ISR. * **************************************************************************************** * @ thread_xp : extended pointer on client thread descriptor. ***************************************************************************************/ void soclib_tty_cmd( xptr_t thread_xp ); /**************************************************************************************** * This function implements the TXT_SYNC_WRITE command registered in the txt_aux_t * structure, using a busy waiting policy, without using the TTY IRQ. * It is used by the kernel do display debug messages on TXT0 terminal, without * interference with another TXT access to another terminal done by the same thread. **************************************************************************************** * @ thread_xp : pointer on the txt_aux_t structure containing the arguments. ***************************************************************************************/ void soclib_tty_aux( void * args ); /**************************************************************************************** * This ISR is executed to handle both the TTY_TX_IRQ and the TTY_RX_IRQ, even if * The RX_IRQ is activated as soon as the TTY_STATUS_RX_FULL bit is 1 in the * TTY_STATUS register, when the TTY_RX_IRQ_ENABLE is non zero, indicating that * the TTY_READ buffer is full and can be read. * The TX_IRQ is activated as soon as the TTY_STATUS_TX_FULL bit is 0 in the * TTY_STATUS register, when the TTY_TX_IRQ_ENABLE is non zero, indicating that * the TTY_WRITE buffer is empty, and can be written. * WARNING : In ALMOS-MKH, the RX_IRQ is always enabled to catch the control signals, * but the TX_IRQ is dynamically enabled by the TXT_WRITE command, and disabled when * the command is completed. * * 1) The ISR first read the TTY_STATUS to get the current state of the TTY_READ and * the TTY_WRITE buffers. * * 2) It try to read the first command registered in the server thread queue associated * to the TTY channel * * 2) The ISR handles the RX when the TTY_READ buffer is full : * . it read the available character from the TTY_READ buffer, and this * acknowledges the RX_IRQ. * . if it is a control character ( ^C / ^D / ^Z ) it translate it to the proper * signal and execute the relevant sigaction for the foreground process. * . if it is a normal character, it try to get the first command registered in the * server thread queue. If it is a TXT_READ, it returns this character to the * command buffer in the client thread. * * 3) The ISR handles the TX when the TTY_WRITE buffer is empty and a TXT_WRITE * . it try to get it copies the * character to the command buffer, acknowledges the TTY_RX_IRQ, and unblock the * associated server thread. * . the control characters ^C / ^D / ^Z are directly handled by the ISR and * translated to the foreground process. * - the the TXT_READ and TXT_WRITE commands. * It gets the command arguments from the first client thread in the TXT chdev queue: * - if TXT_READ, it transfers one byte from the TTY_READ_REG to the command buffer. * It simply returns for retry if TTY_READ_REG is empty. * - if TXT_WRITE, it tries to transfer several bytes from the command buffer to the * TTY_WRITE_REG. If the TTY_WRITE_REG is full, it updates the "count" and "buffer" * command arguments and returns for retry. * When the I/O operation is completed, it sets the status field in the command, unblocks * the server thread, and unblocks the client thread. **************************************************************************************** * @ chdev : local pointer on TXT chdev descriptor. ***************************************************************************************/ void soclib_tty_isr( chdev_t * chdev );