/* * ARC On-Chip(fpga) UART Driver * * Copyright (C) 2010-2012 Synopsys, Inc. (www.synopsys.com) * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * 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 */ #if defined(CONFIG_SERIAL_ARC_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ) #define SUPPORT_SYSRQ #endif #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> /************************************* * ARC UART Hardware Specs ************************************/ #define ARC_UART_TX_FIFO_SIZE 1 /* * UART Register set (this is not a Standards Compliant IP) * Also each reg is Word aligned, but only 8 bits wide */ #define R_ID0 0 #define R_ID1 4 #define R_ID2 8 #define R_ID3 12 #define R_DATA 16 #define R_STS 20 #define R_BAUDL 24 #define R_BAUDH 28 /* Bits for UART Status Reg (R/W) */ #define RXIENB 0x04 /* Receive Interrupt Enable */ #define TXIENB 0x40 /* Transmit Interrupt Enable */ #define RXEMPTY 0x20 /* Receive FIFO Empty: No char receivede */ #define TXEMPTY 0x80 /* Transmit FIFO Empty, thus char can be written into */ #define RXFULL 0x08 /* Receive FIFO full */ #define RXFULL1 0x10 /* Receive FIFO has space for 1 char (tot space=4) */ #define RXFERR 0x01 /* Frame Error: Stop Bit not detected */ #define RXOERR 0x02 /* OverFlow Err: Char recv but RXFULL still set */ /* Uart bit fiddling helpers: lowest level */ #define RBASE(uart, reg) (uart->port.membase + reg) #define UART_REG_SET(u, r, v) writeb((v), RBASE(u, r)) #define UART_REG_GET(u, r) readb(RBASE(u, r)) #define UART_REG_OR(u, r, v) UART_REG_SET(u, r, UART_REG_GET(u, r) | (v)) #define UART_REG_CLR(u, r, v) UART_REG_SET(u, r, UART_REG_GET(u, r) & ~(v)) /* Uart bit fiddling helpers: API level */ #define UART_SET_DATA(uart, val) UART_REG_SET(uart, R_DATA, val) #define UART_GET_DATA(uart) UART_REG_GET(uart, R_DATA) #define UART_SET_BAUDH(uart, val) UART_REG_SET(uart, R_BAUDH, val) #define UART_SET_BAUDL(uart, val) UART_REG_SET(uart, R_BAUDL, val) #define UART_CLR_STATUS(uart, val) UART_REG_CLR(uart, R_STS, val) #define UART_GET_STATUS(uart) UART_REG_GET(uart, R_STS) #define UART_ALL_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, RXIENB|TXIENB) #define UART_RX_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, RXIENB) #define UART_TX_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, TXIENB) #define UART_ALL_IRQ_ENABLE(uart) UART_REG_OR(uart, R_STS, RXIENB|TXIENB) #define UART_RX_IRQ_ENABLE(uart) UART_REG_OR(uart, R_STS, RXIENB) #define UART_TX_IRQ_ENABLE(uart) UART_REG_OR(uart, R_STS, TXIENB) #define ARC_SERIAL_DEV_NAME "ttyARC" struct arc_uart_port { struct uart_port port; unsigned long baud; int is_emulated; /* H/w vs. Instruction Set Simulator */ }; #define to_arc_port(uport) container_of(uport, struct arc_uart_port, port) 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 "arc-uart" static struct uart_driver arc_uart_driver = { .owner = THIS_MODULE, .driver_name = DRIVER_NAME, .dev_name = ARC_SERIAL_DEV_NAME, .major = 0, .minor = 0, .nr = CONFIG_SERIAL_ARC_NR_PORTS, #ifdef CONFIG_SERIAL_ARC_CONSOLE .cons = &arc_console, #endif }; static void arc_serial_stop_rx(struct uart_port *port) { struct arc_uart_port *uart = to_arc_port(port); UART_RX_IRQ_DISABLE(uart); } static void arc_serial_stop_tx(struct uart_port *port) { struct arc_uart_port *uart = to_arc_port(port); while (!(UART_GET_STATUS(uart) & TXEMPTY)) cpu_relax(); UART_TX_IRQ_DISABLE(uart); } /* * Return TIOCSER_TEMT when transmitter is not busy. */ static unsigned int arc_serial_tx_empty(struct uart_port *port) { struct arc_uart_port *uart = to_arc_port(port); unsigned int stat; stat = UART_GET_STATUS(uart); if (stat & TXEMPTY) return TIOCSER_TEMT; return 0; } /* * Driver internal routine, used by both tty(serial core) as well as tx-isr * -Called under spinlock in either cases * -also tty->stopped / tty->hw_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 arc_uart_port *uart) { struct circ_buf *xmit = &uart->port.state->xmit; int sent = 0; unsigned char ch; if (unlikely(uart->port.x_char)) { UART_SET_DATA(uart, uart->port.x_char); uart->port.icount.tx++; uart->port.x_char = 0; sent = 1; } else if (xmit->tail != xmit->head) { /* TODO: uart_circ_empty */ ch = xmit->buf[xmit->tail]; xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); uart->port.icount.tx++; while (!(UART_GET_STATUS(uart) & TXEMPTY)) cpu_relax(); UART_SET_DATA(uart, ch); sent = 1; } /* * If num chars in xmit buffer are too few, ask tty layer for more. * By Hard ISR to schedule processing in software interrupt part */ if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) uart_write_wakeup(&uart->port); if (sent) UART_TX_IRQ_ENABLE(uart); } /* * 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) { struct arc_uart_port *uart = to_arc_port(port); arc_serial_tx_chars(uart); } static void arc_serial_rx_chars(struct arc_uart_port *uart) { struct tty_struct *tty = tty_port_tty_get(&uart->port.state->port); unsigned int status, ch, flg = 0; if (!tty) return; /* * UART has 4 deep RX-FIFO. Driver's recongnition of this fact * is very subtle. Here's how ... * Upon getting a RX-Intr, such that RX-EMPTY=0, meaning data available, * driver reads the DATA Reg and keeps doing that in a loop, until * RX-EMPTY=1. Multiple chars being avail, with a single Interrupt, * before RX-EMPTY=0, implies some sort of buffering going on in the * controller, which is indeed the Rx-FIFO. */ while (!((status = UART_GET_STATUS(uart)) & RXEMPTY)) { ch = UART_GET_DATA(uart); uart->port.icount.rx++; if (unlikely(status & (RXOERR | RXFERR))) { if (status & RXOERR) { uart->port.icount.overrun++; flg = TTY_OVERRUN; UART_CLR_STATUS(uart, RXOERR); } if (status & RXFERR) { uart->port.icount.frame++; flg = TTY_FRAME; UART_CLR_STATUS(uart, RXFERR); } } else flg = TTY_NORMAL; if (unlikely(uart_handle_sysrq_char(&uart->port, ch))) goto done; uart_insert_char(&uart->port, status, RXOERR, ch, flg); done: tty_flip_buffer_push(tty); } tty_kref_put(tty); } /* * 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) { struct arc_uart_port *uart = dev_id; unsigned int status; status = UART_GET_STATUS(uart); /* * Single IRQ for both Rx (data available) Tx (room available) Interrupt * notifications from the UART Controller. * To demultiplex between the two, we check the relevant bits */ if ((status & RXIENB) && !(status & RXEMPTY)) { /* already in ISR, no need of xx_irqsave */ spin_lock(&uart->port.lock); arc_serial_rx_chars(uart); spin_unlock(&uart->port.lock); } if ((status & TXIENB) && (status & TXEMPTY)) { /* Unconditionally disable further Tx-Interrupts. * will be enabled by tx_chars() if needed. */ UART_TX_IRQ_DISABLE(uart); spin_lock(&uart->port.lock); if (!uart_tx_stopped(&uart->port)) arc_serial_tx_chars(uart); spin_unlock(&uart->port.lock); } return IRQ_HANDLED; } static unsigned int arc_serial_get_mctrl(struct uart_port *port) { /* * Pretend we have a Modem status reg and following bits are * always set, to satify the serial core state machine * (DSR) Data Set Ready * (CTS) Clear To Send * (CAR) Carrier Detect */ return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR; } static void arc_serial_set_mctrl(struct uart_port *port, unsigned int mctrl) { /* MCR not present */ } /* Enable Modem Status Interrupts */ static void arc_serial_enable_ms(struct uart_port *port) { /* MSR not present */ } static void arc_serial_break_ctl(struct uart_port *port, int break_state) { /* ARC UART doesn't support sending Break signal */ } static int arc_serial_startup(struct uart_port *port) { struct arc_uart_port *uart = to_arc_port(port); /* Before we hook up the ISR, Disable all UART Interrupts */ UART_ALL_IRQ_DISABLE(uart); if (request_irq(uart->port.irq, arc_serial_isr, 0, "arc uart rx-tx", uart)) { dev_warn(uart->port.dev, "Unable to attach ARC UART intr\n"); return -EBUSY; } UART_RX_IRQ_ENABLE(uart); /* Only Rx IRQ enabled to begin with */ return 0; } /* This is not really needed */ static void arc_serial_shutdown(struct uart_port *port) { struct arc_uart_port *uart = to_arc_port(port); free_irq(uart->port.irq, uart); } static void arc_serial_set_termios(struct uart_port *port, struct ktermios *new, struct ktermios *old) { struct arc_uart_port *uart = to_arc_port(port); unsigned int baud, uartl, uarth, hw_val; unsigned long flags; /* * Use the generic handler so that any specially encoded baud rates * such as SPD_xx flags or "%B0" can be handled * Max Baud I suppose will not be more than current 115K * 4 * Formula for ARC UART is: hw-val = ((CLK/(BAUD*4)) -1) * spread over two 8-bit registers */ baud = uart_get_baud_rate(port, new, old, 0, 460800); hw_val = port->uartclk / (uart->baud * 4) - 1; uartl = hw_val & 0xFF; uarth = (hw_val >> 8) & 0xFF; /* * UART ISS(Instruction Set simulator) emulation has a subtle bug: * A existing value of Baudh = 0 is used as a indication to startup * it's internal state machine. * Thus if baudh is set to 0, 2 times, it chokes. * This happens with BAUD=115200 and the formaula above * Until that is fixed, when running on ISS, we will set baudh to !0 */ if (uart->is_emulated) uarth = 1; spin_lock_irqsave(&port->lock, flags); UART_ALL_IRQ_DISABLE(uart); UART_SET_BAUDL(uart, uartl); UART_SET_BAUDH(uart, uarth); UART_RX_IRQ_ENABLE(uart); /* * UART doesn't support Parity/Hardware Flow Control; * Only supports 8N1 character size */ new->c_cflag &= ~(CMSPAR|CRTSCTS|CSIZE); new->c_cflag |= CS8; if (old) tty_termios_copy_hw(new, old); /* Don't rewrite B0 */ if (tty_termios_baud_rate(new)) tty_termios_encode_baud_rate(new, baud, baud); uart_update_timeout(port, new->c_cflag, baud); spin_unlock_irqrestore(&port->lock, flags); } static const char *arc_serial_type(struct uart_port *port) { struct arc_uart_port *uart = to_arc_port(port); return uart->port.type == PORT_ARC ? DRIVER_NAME : NULL; } static void arc_serial_release_port(struct uart_port *port) { } static int arc_serial_request_port(struct uart_port *port) { return 0; } /* * Verify the new serial_struct (for TIOCSSERIAL). */ static int arc_serial_verify_port(struct uart_port *port, struct serial_struct *ser) { if (port->type != PORT_UNKNOWN && ser->type != PORT_ARC) return -EINVAL; return 0; } /* * Configure/autoconfigure the port. */ static void arc_serial_config_port(struct uart_port *port, int flags) { struct arc_uart_port *uart = to_arc_port(port); if (flags & UART_CONFIG_TYPE) uart->port.type = PORT_ARC; } #if defined(CONFIG_CONSOLE_POLL) || defined(CONFIG_SERIAL_ARC_CONSOLE) static void arc_serial_poll_putchar(struct uart_port *port, unsigned char chr) { struct arc_uart_port *uart = to_arc_port(port); while (!(UART_GET_STATUS(uart) & TXEMPTY)) cpu_relax(); UART_SET_DATA(uart, chr); } #endif #ifdef CONFIG_CONSOLE_POLL static int arc_serial_poll_getchar(struct uart_port *port) { struct arc_uart_port *uart = to_arc_port(port); unsigned char chr; while (!(UART_GET_STATUS(uart) & RXEMPTY)) cpu_relax(); chr = UART_GET_DATA(uart); return chr; } #endif static struct uart_ops arc_serial_pops = { .tx_empty = arc_serial_tx_empty, .set_mctrl = arc_serial_set_mctrl, .get_mctrl = arc_serial_get_mctrl, .stop_tx = arc_serial_stop_tx, .start_tx = arc_serial_start_tx, .stop_rx = arc_serial_stop_rx, .enable_ms = arc_serial_enable_ms, .break_ctl = arc_serial_break_ctl, .startup = arc_serial_startup, .shutdown = arc_serial_shutdown, .set_termios = arc_serial_set_termios, .type = arc_serial_type, .release_port = arc_serial_release_port, .request_port = arc_serial_request_port, .config_port = arc_serial_config_port, .verify_port = arc_serial_verify_port, #ifdef CONFIG_CONSOLE_POLL .poll_put_char = arc_serial_poll_putchar, .poll_get_char = arc_serial_poll_getchar, #endif }; static int arc_uart_init_one(struct platform_device *pdev, struct arc_uart_port *uart) { struct resource *res, *res2; unsigned long *plat_data; if (pdev->id < 0 || pdev->id >= CONFIG_SERIAL_ARC_NR_PORTS) { dev_err(&pdev->dev, "Wrong uart platform device id.\n"); return -ENOENT; } plat_data = ((unsigned long *)(pdev->dev.platform_data)); uart->baud = plat_data[0]; res = platform_get_resource(pdev, IORESOURCE_MEM, 0); if (!res) return -ENODEV; res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0); if (!res2) return -ENODEV; uart->port.mapbase = res->start; uart->port.membase = ioremap_nocache(res->start, resource_size(res)); if (!uart->port.membase) /* No point of dev_err since UART itself is hosed here */ return -ENXIO; uart->port.irq = res2->start; uart->port.dev = &pdev->dev; uart->port.iotype = UPIO_MEM; uart->port.flags = UPF_BOOT_AUTOCONF; uart->port.line = pdev->id; uart->port.ops = &arc_serial_pops; uart->port.uartclk = plat_data[1]; uart->port.fifosize = ARC_UART_TX_FIFO_SIZE; /* * uart_insert_char( ) uses it in decideding whether to ignore a * char or not. Explicitly setting it here, removes the subtelty */ uart->port.ignore_status_mask = 0; /* Real Hardware vs. emulated to work around a bug */ uart->is_emulated = !!plat_data[2]; return 0; } #ifdef CONFIG_SERIAL_ARC_CONSOLE static int arc_serial_console_setup(struct console *co, char *options) { struct uart_port *port; int baud = 115200; int bits = 8; int parity = 'n'; int flow = 'n'; if (co->index < 0 || co->index >= CONFIG_SERIAL_ARC_NR_PORTS) return -ENODEV; /* * The uart port backing the console (e.g. ttyARC1) might not have been * init yet. If so, defer the console setup to after the port. */ port = &arc_uart_ports[co->index].port; if (!port->membase) return -ENODEV; if (options) uart_parse_options(options, &baud, &parity, &bits, &flow); /* * Serial core will call port->ops->set_termios( ) * which will set the baud reg */ return uart_set_options(port, co, baud, parity, bits, flow); } static void arc_serial_console_putchar(struct uart_port *port, int ch) { arc_serial_poll_putchar(port, (unsigned char)ch); } /* * Interrupts are disabled on entering */ static void arc_serial_console_write(struct console *co, const char *s, unsigned int count) { struct uart_port *port = &arc_uart_ports[co->index].port; unsigned long flags; spin_lock_irqsave(&port->lock, flags); uart_console_write(port, s, count, arc_serial_console_putchar); spin_unlock_irqrestore(&port->lock, flags); } static struct console arc_console = { .name = ARC_SERIAL_DEV_NAME, .write = arc_serial_console_write, .device = uart_console_device, .setup = arc_serial_console_setup, .flags = CON_PRINTBUFFER, .index = -1, .data = &arc_uart_driver }; static __init void early_serial_write(struct console *con, const char *s, unsigned int n) { struct uart_port *port = &arc_uart_ports[con->index].port; unsigned int i; for (i = 0; i < n; i++, s++) { if (*s == '\n') arc_serial_poll_putchar(port, '\r'); arc_serial_poll_putchar(port, *s); } } static struct __initdata console arc_early_serial_console = { .name = "early_ARCuart", .write = early_serial_write, .flags = CON_PRINTBUFFER | CON_BOOT, .index = -1 }; static int arc_serial_probe_earlyprintk(struct platform_device *pdev) { arc_early_serial_console.index = pdev->id; arc_uart_init_one(pdev, &arc_uart_ports[pdev->id]); arc_serial_console_setup(&arc_early_serial_console, NULL); register_console(&arc_early_serial_console); return 0; } #else static int arc_serial_probe_earlyprintk(struct platform_device *pdev) { return -ENODEV; } #endif /* CONFIG_SERIAL_ARC_CONSOLE */ static int arc_serial_probe(struct platform_device *pdev) { struct arc_uart_port *uart; int rc; if (is_early_platform_device(pdev)) return arc_serial_probe_earlyprintk(pdev); uart = &arc_uart_ports[pdev->id]; rc = arc_uart_init_one(pdev, uart); if (rc) return rc; return uart_add_one_port(&arc_uart_driver, &uart->port); } static int arc_serial_remove(struct platform_device *pdev) { /* This will never be called */ return 0; } static struct platform_driver arc_platform_driver = { .probe = arc_serial_probe, .remove = arc_serial_remove, .driver = { .name = DRIVER_NAME, .owner = THIS_MODULE, }, }; #ifdef CONFIG_SERIAL_ARC_CONSOLE /* * Register an early platform driver of "earlyprintk" class. * ARCH platform code installs the driver and probes the early devices * The installation could rely on user specifying earlyprintk=xyx in cmd line * or it could be done independently, for all "earlyprintk" class drivers. * [see arch/arc/plat-arcfpga/platform.c] */ early_platform_init("earlyprintk", &arc_platform_driver); #endif /* CONFIG_SERIAL_ARC_CONSOLE */ static int __init arc_serial_init(void) { int ret; ret = uart_register_driver(&arc_uart_driver); if (ret) return ret; ret = platform_driver_register(&arc_platform_driver); if (ret) uart_unregister_driver(&arc_uart_driver); return ret; } static void __exit arc_serial_exit(void) { platform_driver_unregister(&arc_platform_driver); uart_unregister_driver(&arc_uart_driver); } module_init(arc_serial_init); module_exit(arc_serial_exit); MODULE_LICENSE("GPL"); MODULE_ALIAS("plat-arcfpga/uart"); MODULE_AUTHOR("Vineet Gupta"); MODULE_DESCRIPTION("ARC(Synopsys) On-Chip(fpga) serial driver");