From: Filip Kokosinski <[email protected]> This commit adds driver for the FPGA-based LiteUART serial controller from LiteX SoC builder.
The current implementation supports LiteUART configured for 32 bit data width and 8 bit CSR bus width. It does not support IRQ. Signed-off-by: Filip Kokosinski <[email protected]> Signed-off-by: Mateusz Holenko <[email protected]> --- MAINTAINERS | 1 + drivers/tty/serial/Kconfig | 30 +++ drivers/tty/serial/Makefile | 1 + drivers/tty/serial/liteuart.c | 382 +++++++++++++++++++++++++++++++ include/uapi/linux/serial_core.h | 3 + 5 files changed, 417 insertions(+) create mode 100644 drivers/tty/serial/liteuart.c diff --git a/MAINTAINERS b/MAINTAINERS index 65a6cf296..d108b6044 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -9467,6 +9467,7 @@ M: Karol Gugala <[email protected]> M: Mateusz Holenko <[email protected]> S: Maintained F: Documentation/devicetree/bindings/serial/litex,liteuart.txt +F: drivers/tty/serial/liteuart.c LIVE PATCHING M: Josh Poimboeuf <[email protected]> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig index 4789b5d62..b01fe12a1 100644 --- a/drivers/tty/serial/Kconfig +++ b/drivers/tty/serial/Kconfig @@ -1571,6 +1571,36 @@ config SERIAL_MILBEAUT_USIO_CONSOLE receives all kernel messages and warnings and which allows logins in single user mode). +config SERIAL_LITEUART + tristate "LiteUART serial port support" + depends on HAS_IOMEM + depends on OF + select SERIAL_CORE + help + This driver is for the FPGA-based LiteUART serial controller from LiteX + SoC builder. + + Say 'Y' here if you wish to use the LiteUART serial controller. + Otherwise, say 'N'. + +config SERIAL_LITEUART_NR_PORTS + int "Number of LiteUART ports" + depends on SERIAL_LITEUART + default "1" + help + Set this to the number of serial ports you want the driver + to support. + +config SERIAL_LITEUART_CONSOLE + bool "LiteUART serial port console support" + depends on SERIAL_LITEUART=y + select SERIAL_CORE_CONSOLE + help + Say 'Y' here if you wish to use the FPGA-based LiteUART serial controller + from LiteX SoC builder as the system console (the system console is the + device which receives all kernel messages and warnings and which allows + logins in single user mode). Otherwise, say 'N'. + endmenu config SERIAL_MCTRL_GPIO diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile index 863f47056..c8d7e2046 100644 --- a/drivers/tty/serial/Makefile +++ b/drivers/tty/serial/Makefile @@ -89,6 +89,7 @@ obj-$(CONFIG_SERIAL_OWL) += owl-uart.o obj-$(CONFIG_SERIAL_RDA) += rda-uart.o obj-$(CONFIG_SERIAL_MILBEAUT_USIO) += milbeaut_usio.o obj-$(CONFIG_SERIAL_SIFIVE) += sifive.o +obj-$(CONFIG_SERIAL_LITEUART) += liteuart.o # GPIOLIB helpers for modem control lines obj-$(CONFIG_SERIAL_MCTRL_GPIO) += serial_mctrl_gpio.o diff --git a/drivers/tty/serial/liteuart.c b/drivers/tty/serial/liteuart.c new file mode 100644 index 000000000..4c4eaa73f --- /dev/null +++ b/drivers/tty/serial/liteuart.c @@ -0,0 +1,382 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * LiteUART serial controller (LiteX) Driver + * + * Copyright (C) 2019 Antmicro Ltd <www.antmicro.com> + */ + +#include <linux/console.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/of_address.h> +#include <linux/of_platform.h> +#include <linux/serial.h> +#include <linux/serial_core.h> +#include <linux/timer.h> +#include <linux/tty_flip.h> + +/* module-related defines */ +#define DRIVER_NAME "liteuart" +#define DRIVER_MAJOR 0 +#define DRIVER_MINOR 0 +#define DEV_NAME "ttyLXU" + +/* base address offsets */ +#define OFF_RXTX 0x00 +#define OFF_TXFULL 0x04 +#define OFF_RXEMPTY 0x08 +#define OFF_EV_STATUS 0x0c +#define OFF_EV_PENDING 0x10 +#define OFF_EV_ENABLE 0x14 + +/* events */ +#define EV_TX 0x1 +#define EV_RX 0x2 + +/* setting/getting registers */ +#ifdef __LITTLE_ENDIAN +# define PORT_REG_SET(port, off, val) iowrite32(val, port->membase + \ + OFF_##off) +# define PORT_REG_GET(port, off) ioread32(port->membase + OFF_##off) +#else +# define PORT_REG_SET(port, off, val) iowrite32be(val, port->membase + \ + OFF_##off) +# define PORT_REG_GET(port, off) ioread32be(port->membase + OFF_##off) +#endif + +struct liteuart_port { + struct uart_port port; + struct timer_list timer; +}; + +#define to_liteuart_port(port) container_of(port, struct liteuart_port, port) + +static struct liteuart_port liteuart_ports[CONFIG_SERIAL_LITEUART_NR_PORTS]; + +#ifdef CONFIG_SERIAL_LITEUART_CONSOLE +static struct console liteuart_console; +#endif + +static struct uart_driver liteuart_driver = { + .owner = THIS_MODULE, + .driver_name = DRIVER_NAME, + .dev_name = DEV_NAME, + .major = DRIVER_MAJOR, + .minor = DRIVER_MINOR, + .nr = CONFIG_SERIAL_LITEUART_NR_PORTS, +#ifdef CONFIG_SERIAL_LITEUART_CONSOLE + .cons = &liteuart_console, +#endif +}; + +static void liteuart_timer(struct timer_list *t) +{ + struct liteuart_port *uart = from_timer(uart, t, timer); + struct uart_port *port = &uart->port; + unsigned int flg = TTY_NORMAL; + int ch; + unsigned int status; + + while ((status = !PORT_REG_GET(port, RXEMPTY)) == 1) { + ch = PORT_REG_GET(port, RXTX); + port->icount.rx++; + + /* necessary for RXEMPTY to refresh its value */ + PORT_REG_SET(port, EV_PENDING, EV_TX | EV_RX); + + /* no overflow bits in status */ + if (!(uart_handle_sysrq_char(port, ch))) + uart_insert_char(port, status, 0, ch, flg); + + tty_flip_buffer_push(&port->state->port); + } + + mod_timer(&uart->timer, jiffies + uart_poll_timeout(port)); +} + +static void liteuart_putchar(struct uart_port *port, int ch) +{ + while (PORT_REG_GET(port, TXFULL)) + cpu_relax(); + + PORT_REG_SET(port, RXTX, ch); +} + +static unsigned int liteuart_tx_empty(struct uart_port *port) +{ + /* not really tx empty, just checking if tx is not full */ + if (!PORT_REG_GET(port, TXFULL)) + return TIOCSER_TEMT; + + return 0; +} + +static void liteuart_set_mctrl(struct uart_port *port, unsigned int mctrl) +{ + /* modem control register is not present in LiteUART */ +} + +static unsigned int liteuart_get_mctrl(struct uart_port *port) +{ + return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR; +} + +static void liteuart_stop_tx(struct uart_port *port) +{ +} + +static void liteuart_start_tx(struct uart_port *port) +{ + struct circ_buf *xmit = &port->state->xmit; + unsigned char ch; + + if (unlikely(port->x_char)) { + PORT_REG_SET(port, RXTX, port->x_char); + port->icount.tx++; + port->x_char = 0; + } else if (!uart_circ_empty(xmit)) { + while (xmit->head != xmit->tail) { + ch = xmit->buf[xmit->tail]; + xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); + port->icount.tx++; + liteuart_putchar(port, ch); + } + } + + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) + uart_write_wakeup(port); +} + +static void liteuart_stop_rx(struct uart_port *port) +{ + struct liteuart_port *uart = to_liteuart_port(port); + + /* just delete timer */ + del_timer(&uart->timer); +} + +static void liteuart_break_ctl(struct uart_port *port, int break_state) +{ + /* LiteUART doesn't support sending break signal */ +} + +static int liteuart_startup(struct uart_port *port) +{ + struct liteuart_port *uart = to_liteuart_port(port); + + /* disable events */ + PORT_REG_SET(port, EV_ENABLE, 0); + + /* prepare timer for polling */ + timer_setup(&uart->timer, liteuart_timer, 0); + mod_timer(&uart->timer, jiffies + uart_poll_timeout(port)); + + return 0; +} + +static void liteuart_shutdown(struct uart_port *port) +{ +} + +static void liteuart_set_termios(struct uart_port *port, struct ktermios *new, + struct ktermios *old) +{ + unsigned int baud; + unsigned long flags; + + spin_lock_irqsave(&port->lock, flags); + + /* update baudrate */ + baud = uart_get_baud_rate(port, new, old, 0, 460800); + uart_update_timeout(port, new->c_cflag, baud); + + spin_unlock_irqrestore(&port->lock, flags); +} + +static const char *liteuart_type(struct uart_port *port) +{ + return (port->type == PORT_LITEUART) ? DRIVER_NAME : NULL; +} + +static void liteuart_release_port(struct uart_port *port) +{ +} + +static int liteuart_request_port(struct uart_port *port) +{ + return 0; +} + +static void liteuart_config_port(struct uart_port *port, int flags) +{ + if (flags & UART_CONFIG_TYPE) + port->type = PORT_LITEUART; +} + +static int liteuart_verify_port(struct uart_port *port, + struct serial_struct *ser) +{ + if (port->type != PORT_UNKNOWN && ser->type != PORT_LITEUART) + return -EINVAL; + + return 0; +} + +static const struct uart_ops liteuart_ops = { + .tx_empty = liteuart_tx_empty, + .set_mctrl = liteuart_set_mctrl, + .get_mctrl = liteuart_get_mctrl, + .stop_tx = liteuart_stop_tx, + .start_tx = liteuart_start_tx, + .stop_rx = liteuart_stop_rx, + .break_ctl = liteuart_break_ctl, + .startup = liteuart_startup, + .shutdown = liteuart_shutdown, + .set_termios = liteuart_set_termios, + .type = liteuart_type, + .release_port = liteuart_release_port, + .request_port = liteuart_request_port, + .config_port = liteuart_config_port, + .verify_port = liteuart_verify_port, +}; + +static int liteuart_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct liteuart_port *uart; + struct uart_port *port; + int dev_id; + + /* no device tree */ + if (!np) + return -ENODEV; + + dev_id = of_alias_get_id(np, "serial"); + if (dev_id < 0 || dev_id >= CONFIG_SERIAL_LITEUART_NR_PORTS) + return -EINVAL; + + uart = &liteuart_ports[dev_id]; + port = &uart->port; + + /* get {map,mem}base */ + port->mapbase = platform_get_resource(pdev, IORESOURCE_MEM, 0)->start; + port->membase = of_iomap(np, 0); + if (!port->membase) + return -ENXIO; + + /* values not from device tree */ + port->dev = &pdev->dev; + port->iotype = UPIO_MEM; + port->flags = UPF_BOOT_AUTOCONF; + port->ops = &liteuart_ops; + port->regshift = 2; + port->fifosize = 16; + port->iobase = 1; + port->type = PORT_UNKNOWN; + port->line = dev_id; + + return uart_add_one_port(&liteuart_driver, + &liteuart_ports[dev_id].port); +} + +static int liteuart_remove(struct platform_device *pdev) +{ + return 0; +} + +static const struct of_device_id liteuart_of_match[] = { + { .compatible = "litex,liteuart" }, + {} +}; +MODULE_DEVICE_TABLE(of, liteuart_of_match); + +static struct platform_driver liteuart_platform_driver = { + .probe = liteuart_probe, + .remove = liteuart_remove, + .driver = { + .name = DRIVER_NAME, + .of_match_table = of_match_ptr(liteuart_of_match), + }, +}; + +#ifdef CONFIG_SERIAL_LITEUART_CONSOLE + +static void liteuart_console_write(struct console *co, const char *s, + unsigned int count) +{ + struct uart_port *port = &liteuart_ports[co->index].port; + unsigned long flags; + + spin_lock_irqsave(&port->lock, flags); + uart_console_write(port, s, count, liteuart_putchar); + spin_unlock_irqrestore(&port->lock, flags); +} + +static int liteuart_console_setup(struct console *co, char *options) +{ + struct uart_port *port; + int baud = 115200; + int bits = 8; + int parity = 'n'; + int flow = 'n'; + + port = &liteuart_ports[co->index].port; + if (!port->membase) + return -ENODEV; + + if (options) + uart_parse_options(options, &baud, &parity, &bits, &flow); + + return uart_set_options(port, co, baud, parity, bits, flow); +} + +static struct console liteuart_console = { + .name = DRIVER_NAME, + .write = liteuart_console_write, + .device = uart_console_device, + .setup = liteuart_console_setup, + .flags = CON_PRINTBUFFER, + .index = -1, + .data = &liteuart_driver, +}; + +static int __init liteuart_console_init(void) +{ + register_console(&liteuart_console); + + return 0; +} + +console_initcall(liteuart_console_init); +#endif /* CONFIG_SERIAL_LITEUART_CONSOLE */ + +static int __init liteuart_init(void) +{ + int res; + + res = uart_register_driver(&liteuart_driver); + if (res) + return res; + + res = platform_driver_register(&liteuart_platform_driver); + if (res) { + uart_unregister_driver(&liteuart_driver); + return res; + } + + return 0; +} + +static void __exit liteuart_exit(void) +{ + platform_driver_unregister(&liteuart_platform_driver); + uart_unregister_driver(&liteuart_driver); +} + +module_init(liteuart_init); +module_exit(liteuart_exit); + +MODULE_AUTHOR("Antmicro Ltd <www.antmicro.com>"); +MODULE_DESCRIPTION("LiteUART serial driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:" DRIVER_NAME); diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h index 0f4f87a6f..8fe6b0bf8 100644 --- a/include/uapi/linux/serial_core.h +++ b/include/uapi/linux/serial_core.h @@ -293,4 +293,7 @@ /* Freescale Linflex UART */ #define PORT_LINFLEXUART 121 +/* LiteUART */ +#define PORT_LITEUART 122 + #endif /* _UAPILINUX_SERIAL_CORE_H */ -- 2.23.0
