diff options
Diffstat (limited to 'drivers/tty/serial/arc_uart.c')
| -rw-r--r-- | drivers/tty/serial/arc_uart.c | 684 |
1 files changed, 684 insertions, 0 deletions
diff --git a/drivers/tty/serial/arc_uart.c b/drivers/tty/serial/arc_uart.c new file mode 100644 index 000000000..f3ccc59d8 --- /dev/null +++ b/drivers/tty/serial/arc_uart.c @@ -0,0 +1,684 @@ +// 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 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(port, reg) (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; +}; + +#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) +{ + UART_RX_IRQ_DISABLE(port); +} + +static void arc_serial_stop_tx(struct uart_port *port) +{ + while (!(UART_GET_STATUS(port) & TXEMPTY)) + cpu_relax(); + + UART_TX_IRQ_DISABLE(port); +} + +/* + * Return TIOCSER_TEMT when transmitter is not busy. + */ +static unsigned int arc_serial_tx_empty(struct uart_port *port) +{ + unsigned int stat; + + stat = UART_GET_STATUS(port); + 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->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) +{ + struct circ_buf *xmit = &port->state->xmit; + int sent = 0; + unsigned char ch; + + if (unlikely(port->x_char)) { + UART_SET_DATA(port, port->x_char); + port->icount.tx++; + port->x_char = 0; + sent = 1; + } else if (!uart_circ_empty(xmit)) { + ch = xmit->buf[xmit->tail]; + xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); + port->icount.tx++; + while (!(UART_GET_STATUS(port) & TXEMPTY)) + cpu_relax(); + UART_SET_DATA(port, 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(port); + + if (sent) + UART_TX_IRQ_ENABLE(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) +{ + arc_serial_tx_chars(port); +} + +static void arc_serial_rx_chars(struct uart_port *port, unsigned int status) +{ + unsigned int ch, flg = 0; + + /* + * 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. + */ + do { + /* + * This could be an Rx Intr for err (no data), + * so check err and clear that Intr first + */ + if (unlikely(status & (RXOERR | RXFERR))) { + if (status & RXOERR) { + port->icount.overrun++; + flg = TTY_OVERRUN; + UART_CLR_STATUS(port, RXOERR); + } + + if (status & RXFERR) { + port->icount.frame++; + flg = TTY_FRAME; + UART_CLR_STATUS(port, RXFERR); + } + } else + flg = TTY_NORMAL; + + if (status & RXEMPTY) + continue; + + ch = UART_GET_DATA(port); + port->icount.rx++; + + if (!(uart_handle_sysrq_char(port, ch))) + uart_insert_char(port, status, RXOERR, ch, flg); + + tty_flip_buffer_push(&port->state->port); + } while (!((status = UART_GET_STATUS(port)) & RXEMPTY)); +} + +/* + * 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 uart_port *port = dev_id; + unsigned int status; + + status = UART_GET_STATUS(port); + + /* + * 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) { + + /* already in ISR, no need of xx_irqsave */ + spin_lock(&port->lock); + arc_serial_rx_chars(port, status); + spin_unlock(&port->lock); + } + + if ((status & TXIENB) && (status & TXEMPTY)) { + + /* Unconditionally disable further Tx-Interrupts. + * will be enabled by tx_chars() if needed. + */ + UART_TX_IRQ_DISABLE(port); + + spin_lock(&port->lock); + + if (!uart_tx_stopped(port)) + arc_serial_tx_chars(port); + + spin_unlock(&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 */ +} + +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) +{ + /* Before we hook up the ISR, Disable all UART Interrupts */ + UART_ALL_IRQ_DISABLE(port); + + if (request_irq(port->irq, arc_serial_isr, 0, "arc uart rx-tx", port)) { + dev_warn(port->dev, "Unable to attach ARC UART intr\n"); + return -EBUSY; + } + + UART_RX_IRQ_ENABLE(port); /* Only Rx IRQ enabled to begin with */ + + return 0; +} + +/* This is not really needed */ +static void arc_serial_shutdown(struct uart_port *port) +{ + free_irq(port->irq, port); +} + +static void +arc_serial_set_termios(struct uart_port *port, struct ktermios *new, + const 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; + + spin_lock_irqsave(&port->lock, flags); + + UART_ALL_IRQ_DISABLE(port); + + UART_SET_BAUDL(port, uartl); + UART_SET_BAUDH(port, uarth); + + UART_RX_IRQ_ENABLE(port); + + /* + * 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) +{ + return 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) +{ + if (flags & UART_CONFIG_TYPE) + port->type = PORT_ARC; +} + +#ifdef CONFIG_CONSOLE_POLL + +static void arc_serial_poll_putchar(struct uart_port *port, unsigned char chr) +{ + while (!(UART_GET_STATUS(port) & TXEMPTY)) + cpu_relax(); + + UART_SET_DATA(port, chr); +} + +static int arc_serial_poll_getchar(struct uart_port *port) +{ + unsigned char chr; + + while (!(UART_GET_STATUS(port) & RXEMPTY)) + cpu_relax(); + + chr = UART_GET_DATA(port); + return chr; +} +#endif + +static const 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, + .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 +}; + +#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, unsigned char ch) +{ + while (!(UART_GET_STATUS(port) & TXEMPTY)) + cpu_relax(); + + UART_SET_DATA(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 void arc_early_serial_write(struct console *con, const char *s, + unsigned int n) +{ + struct earlycon_device *dev = con->data; + + uart_console_write(&dev->port, s, n, arc_serial_console_putchar); +} + +static int __init arc_early_console_setup(struct earlycon_device *dev, + const char *opt) +{ + struct uart_port *port = &dev->port; + unsigned int l, h, hw_val; + + if (!dev->port.membase) + return -ENODEV; + + hw_val = port->uartclk / (dev->baud * 4) - 1; + l = hw_val & 0xFF; + h = (hw_val >> 8) & 0xFF; + + UART_SET_BAUDL(port, l); + UART_SET_BAUDH(port, h); + + dev->con->write = arc_early_serial_write; + return 0; +} +OF_EARLYCON_DECLARE(arc_uart, "snps,arc-uart", arc_early_console_setup); + +#endif /* CONFIG_SERIAL_ARC_CONSOLE */ + +static int arc_serial_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct arc_uart_port *uart; + struct uart_port *port; + int dev_id; + u32 val; + + /* no device tree device */ + if (!np) + return -ENODEV; + + dev_id = of_alias_get_id(np, "serial"); + if (dev_id < 0) + dev_id = 0; + + if (dev_id >= ARRAY_SIZE(arc_uart_ports)) { + dev_err(&pdev->dev, "serial%d out of range\n", dev_id); + return -EINVAL; + } + + uart = &arc_uart_ports[dev_id]; + port = &uart->port; + + if (of_property_read_u32(np, "clock-frequency", &val)) { + dev_err(&pdev->dev, "clock-frequency property NOTset\n"); + return -EINVAL; + } + port->uartclk = val; + + if (of_property_read_u32(np, "current-speed", &val)) { + dev_err(&pdev->dev, "current-speed property NOT set\n"); + return -EINVAL; + } + uart->baud = val; + + port->membase = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(port->membase)) { + /* No point of dev_err since UART itself is hosed here */ + return PTR_ERR(port->membase); + } + + port->irq = irq_of_parse_and_map(np, 0); + + port->dev = &pdev->dev; + port->iotype = UPIO_MEM; + port->flags = UPF_BOOT_AUTOCONF; + port->line = dev_id; + port->ops = &arc_serial_pops; + port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_ARC_CONSOLE); + + 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 + */ + port->ignore_status_mask = 0; + + return uart_add_one_port(&arc_uart_driver, &arc_uart_ports[dev_id].port); +} + +static int arc_serial_remove(struct platform_device *pdev) +{ + /* This will never be called */ + return 0; +} + +static const struct of_device_id arc_uart_dt_ids[] = { + { .compatible = "snps,arc-uart" }, + { /* Sentinel */ } +}; +MODULE_DEVICE_TABLE(of, arc_uart_dt_ids); + +static struct platform_driver arc_platform_driver = { + .probe = arc_serial_probe, + .remove = arc_serial_remove, + .driver = { + .name = DRIVER_NAME, + .of_match_table = arc_uart_dt_ids, + }, +}; + +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("platform:" DRIVER_NAME); +MODULE_AUTHOR("Vineet Gupta"); +MODULE_DESCRIPTION("ARC(Synopsys) On-Chip(fpga) serial driver"); |