| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * LiteUART serial controller (LiteX) Driver |
| * |
| * Copyright (C) 2019-2020 Antmicro <www.antmicro.com> |
| */ |
| |
| #include <linux/console.h> |
| #include <linux/litex.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/slab.h> |
| #include <linux/timer.h> |
| #include <linux/tty_flip.h> |
| #include <linux/xarray.h> |
| |
| /* |
| * CSRs definitions (base address offsets + width) |
| * |
| * The definitions below are true for LiteX SoC configured for 8-bit CSR Bus, |
| * 32-bit aligned. |
| * |
| * Supporting other configurations might require new definitions or a more |
| * generic way of indexing the LiteX CSRs. |
| * |
| * For more details on how CSRs are defined and handled in LiteX, see comments |
| * in the LiteX SoC Driver: drivers/soc/litex/litex_soc_ctrl.c |
| */ |
| #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 |
| |
| struct liteuart_port { |
| struct uart_port port; |
| struct timer_list timer; |
| u32 id; |
| }; |
| |
| #define to_liteuart_port(port) container_of(port, struct liteuart_port, port) |
| |
| static DEFINE_XARRAY_FLAGS(liteuart_array, XA_FLAGS_ALLOC); |
| |
| #ifdef CONFIG_SERIAL_LITEUART_CONSOLE |
| static struct console liteuart_console; |
| #endif |
| |
| static struct uart_driver liteuart_driver = { |
| .owner = THIS_MODULE, |
| .driver_name = "liteuart", |
| .dev_name = "ttyLXU", |
| .major = 0, |
| .minor = 0, |
| .nr = CONFIG_SERIAL_LITEUART_MAX_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 char __iomem *membase = port->membase; |
| unsigned int flg = TTY_NORMAL; |
| int ch; |
| unsigned long status; |
| |
| while ((status = !litex_read8(membase + OFF_RXEMPTY)) == 1) { |
| ch = litex_read8(membase + OFF_RXTX); |
| port->icount.rx++; |
| |
| /* necessary for RXEMPTY to refresh its value */ |
| litex_write8(membase + OFF_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, unsigned char ch) |
| { |
| while (litex_read8(port->membase + OFF_TXFULL)) |
| cpu_relax(); |
| |
| litex_write8(port->membase + OFF_RXTX, ch); |
| } |
| |
| static unsigned int liteuart_tx_empty(struct uart_port *port) |
| { |
| /* not really tx empty, just checking if tx is not full */ |
| if (!litex_read8(port->membase + OFF_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)) { |
| litex_write8(port->membase + OFF_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 */ |
| litex_write8(port->membase + OFF_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 "liteuart"; |
| } |
| |
| 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) |
| { |
| /* |
| * Driver core for serial ports forces a non-zero value for port type. |
| * Write an arbitrary value here to accommodate the serial core driver, |
| * as ID part of UAPI is redundant. |
| */ |
| port->type = 1; |
| } |
| |
| static int liteuart_verify_port(struct uart_port *port, |
| struct serial_struct *ser) |
| { |
| if (port->type != PORT_UNKNOWN && ser->type != 1) |
| 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 liteuart_port *uart; |
| struct uart_port *port; |
| struct xa_limit limit; |
| int dev_id, ret; |
| |
| /* look for aliases; auto-enumerate for free index if not found */ |
| dev_id = of_alias_get_id(pdev->dev.of_node, "serial"); |
| if (dev_id < 0) |
| limit = XA_LIMIT(0, CONFIG_SERIAL_LITEUART_MAX_PORTS); |
| else |
| limit = XA_LIMIT(dev_id, dev_id); |
| |
| uart = devm_kzalloc(&pdev->dev, sizeof(struct liteuart_port), GFP_KERNEL); |
| if (!uart) |
| return -ENOMEM; |
| |
| ret = xa_alloc(&liteuart_array, &dev_id, uart, limit, GFP_KERNEL); |
| if (ret) |
| return ret; |
| |
| uart->id = dev_id; |
| port = &uart->port; |
| |
| /* get membase */ |
| port->membase = devm_platform_get_and_ioremap_resource(pdev, 0, NULL); |
| if (IS_ERR(port->membase)) { |
| ret = PTR_ERR(port->membase); |
| goto err_erase_id; |
| } |
| |
| /* 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; |
| spin_lock_init(&port->lock); |
| |
| platform_set_drvdata(pdev, port); |
| |
| ret = uart_add_one_port(&liteuart_driver, &uart->port); |
| if (ret) |
| goto err_erase_id; |
| |
| return 0; |
| |
| err_erase_id: |
| xa_erase(&liteuart_array, uart->id); |
| |
| return ret; |
| } |
| |
| static int liteuart_remove(struct platform_device *pdev) |
| { |
| struct uart_port *port = platform_get_drvdata(pdev); |
| struct liteuart_port *uart = to_liteuart_port(port); |
| |
| uart_remove_one_port(&liteuart_driver, port); |
| xa_erase(&liteuart_array, uart->id); |
| |
| 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 = "liteuart", |
| .of_match_table = liteuart_of_match, |
| }, |
| }; |
| |
| #ifdef CONFIG_SERIAL_LITEUART_CONSOLE |
| |
| static void liteuart_console_write(struct console *co, const char *s, |
| unsigned int count) |
| { |
| struct liteuart_port *uart; |
| struct uart_port *port; |
| unsigned long flags; |
| |
| uart = (struct liteuart_port *)xa_load(&liteuart_array, co->index); |
| port = &uart->port; |
| |
| 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 liteuart_port *uart; |
| struct uart_port *port; |
| int baud = 115200; |
| int bits = 8; |
| int parity = 'n'; |
| int flow = 'n'; |
| |
| uart = (struct liteuart_port *)xa_load(&liteuart_array, co->index); |
| if (!uart) |
| return -ENODEV; |
| |
| port = &uart->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 = "liteuart", |
| .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); |
| |
| static void early_liteuart_write(struct console *console, const char *s, |
| unsigned int count) |
| { |
| struct earlycon_device *device = console->data; |
| struct uart_port *port = &device->port; |
| |
| uart_console_write(port, s, count, liteuart_putchar); |
| } |
| |
| static int __init early_liteuart_setup(struct earlycon_device *device, |
| const char *options) |
| { |
| if (!device->port.membase) |
| return -ENODEV; |
| |
| device->con->write = early_liteuart_write; |
| return 0; |
| } |
| |
| OF_EARLYCON_DECLARE(liteuart, "litex,liteuart", early_liteuart_setup); |
| #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 <www.antmicro.com>"); |
| MODULE_DESCRIPTION("LiteUART serial driver"); |
| MODULE_LICENSE("GPL v2"); |
| MODULE_ALIAS("platform:liteuart"); |