// SPDX-License-Identifier: GPL-2.0 /* * ARC On-Chip(fpga) UART Driver * * Copyright (C) 2010-2012 Synopsys, Inc. (www.synopsys.com) * * vineetg: July 10th 2012 * -Decoupled the driver from arch/arc * +Using platform_get_resource() for irq/membase (thx to bfin_uart.c) * +Using early_platform_xxx() for early console (thx to mach-shmobile/xxx) * * Vineetg: Aug 21st 2010 * -Is uart_tx_stopped() not done in tty write path as it has already been * taken care of, in serial core * * Vineetg: Aug 18th 2010 * -New Serial Core based ARC UART driver * -Derived largely from blackfin driver albiet with some major tweaks * * TODO: * -check if sysreq works */ #include <linux/module.h> #include <linux/serial.h> #include <linux/console.h> #include <linux/sysrq.h> #include <linux/platform_device.h> #include <linux/tty.h> #include <linux/tty_flip.h> #include <linux/serial_core.h> #include <linux/io.h> #include <linux/of_irq.h> #include <linux/of_address.h> /************************************* * ARC UART Hardware Specs ************************************/ #define ARC_UART_TX_FIFO_SIZE … /* * UART Register set (this is not a Standards Compliant IP) * Also each reg is Word aligned, but only 8 bits wide */ #define R_ID0 … #define R_ID1 … #define R_ID2 … #define R_ID3 … #define R_DATA … #define R_STS … #define R_BAUDL … #define R_BAUDH … /* Bits for UART Status Reg (R/W) */ #define RXIENB … #define TXIENB … #define RXEMPTY … #define TXEMPTY … #define RXFULL … #define RXFULL1 … #define RXFERR … #define RXOERR … /* Uart bit fiddling helpers: lowest level */ #define RBASE(port, reg) … #define UART_REG_SET(u, r, v) … #define UART_REG_GET(u, r) … #define UART_REG_OR(u, r, v) … #define UART_REG_CLR(u, r, v) … /* Uart bit fiddling helpers: API level */ #define UART_SET_DATA(uart, val) … #define UART_GET_DATA(uart) … #define UART_SET_BAUDH(uart, val) … #define UART_SET_BAUDL(uart, val) … #define UART_CLR_STATUS(uart, val) … #define UART_GET_STATUS(uart) … #define UART_ALL_IRQ_DISABLE(uart) … #define UART_RX_IRQ_DISABLE(uart) … #define UART_TX_IRQ_DISABLE(uart) … #define UART_ALL_IRQ_ENABLE(uart) … #define UART_RX_IRQ_ENABLE(uart) … #define UART_TX_IRQ_ENABLE(uart) … #define ARC_SERIAL_DEV_NAME … struct arc_uart_port { … }; #define to_arc_port(uport) … static struct arc_uart_port arc_uart_ports[CONFIG_SERIAL_ARC_NR_PORTS]; #ifdef CONFIG_SERIAL_ARC_CONSOLE static struct console arc_console; #endif #define DRIVER_NAME … static struct uart_driver arc_uart_driver = …; static void arc_serial_stop_rx(struct uart_port *port) { … } static void arc_serial_stop_tx(struct uart_port *port) { … } /* * Return TIOCSER_TEMT when transmitter is not busy. */ static unsigned int arc_serial_tx_empty(struct uart_port *port) { … } /* * Driver internal routine, used by both tty(serial core) as well as tx-isr * -Called under spinlock in either cases * -also tty->flow.stopped has already been checked * = by uart_start( ) before calling us * = tx_ist checks that too before calling */ static void arc_serial_tx_chars(struct uart_port *port) { … } /* * port is locked and interrupts are disabled * uart_start( ) calls us under the port spinlock irqsave */ static void arc_serial_start_tx(struct uart_port *port) { … } static void arc_serial_rx_chars(struct uart_port *port, unsigned int status) { … } /* * A note on the Interrupt handling state machine of this driver * * kernel printk writes funnel thru the console driver framework and in order * to keep things simple as well as efficient, it writes to UART in polled * mode, in one shot, and exits. * * OTOH, Userland output (via tty layer), uses interrupt based writes as there * can be undeterministic delay between char writes. * * Thus Rx-interrupts are always enabled, while tx-interrupts are by default * disabled. * * When tty has some data to send out, serial core calls driver's start_tx * which * -checks-if-tty-buffer-has-char-to-send * -writes-data-to-uart * -enable-tx-intr * * Once data bits are pushed out, controller raises the Tx-room-avail-Interrupt. * The first thing Tx ISR does is disable further Tx interrupts (as this could * be the last char to send, before settling down into the quiet polled mode). * It then calls the exact routine used by tty layer write to send out any * more char in tty buffer. In case of sending, it re-enables Tx-intr. In case * of no data, it remains disabled. * This is how the transmit state machine is dynamically switched on/off */ static irqreturn_t arc_serial_isr(int irq, void *dev_id) { … } static unsigned int arc_serial_get_mctrl(struct uart_port *port) { … } static void arc_serial_set_mctrl(struct uart_port *port, unsigned int mctrl) { … } static void arc_serial_break_ctl(struct uart_port *port, int break_state) { … } static int arc_serial_startup(struct uart_port *port) { … } /* This is not really needed */ static void arc_serial_shutdown(struct uart_port *port) { … } static void arc_serial_set_termios(struct uart_port *port, struct ktermios *new, const struct ktermios *old) { … } static const char *arc_serial_type(struct uart_port *port) { … } static void arc_serial_release_port(struct uart_port *port) { … } static int arc_serial_request_port(struct uart_port *port) { … } /* * Verify the new serial_struct (for TIOCSSERIAL). */ static int arc_serial_verify_port(struct uart_port *port, struct serial_struct *ser) { … } /* * Configure/autoconfigure the port. */ static void arc_serial_config_port(struct uart_port *port, int flags) { … } #ifdef CONFIG_CONSOLE_POLL static void arc_serial_poll_putchar(struct uart_port *port, unsigned char chr) { … } static int arc_serial_poll_getchar(struct uart_port *port) { … } #endif static const struct uart_ops arc_serial_pops = …; #ifdef CONFIG_SERIAL_ARC_CONSOLE static int arc_serial_console_setup(struct console *co, char *options) { … } static void arc_serial_console_putchar(struct uart_port *port, unsigned char ch) { … } /* * Interrupts are disabled on entering */ static void arc_serial_console_write(struct console *co, const char *s, unsigned int count) { … } static struct console arc_console = …; static void arc_early_serial_write(struct console *con, const char *s, unsigned int n) { … } static int __init arc_early_console_setup(struct earlycon_device *dev, const char *opt) { … } OF_EARLYCON_DECLARE(…); #endif /* CONFIG_SERIAL_ARC_CONSOLE */ static int arc_serial_probe(struct platform_device *pdev) { … } static const struct of_device_id arc_uart_dt_ids[] = …; MODULE_DEVICE_TABLE(of, arc_uart_dt_ids); static struct platform_driver arc_platform_driver = …; static int __init arc_serial_init(void) { … } static void __exit arc_serial_exit(void) { … } module_init(…) …; module_exit(arc_serial_exit); MODULE_LICENSE(…) …; MODULE_ALIAS(…) …; MODULE_AUTHOR(…) …; MODULE_DESCRIPTION(…) …;
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