// SPDX-License-Identifier: GPL-2.0 /* * Atheros AR933X SoC built-in UART driver * * Copyright (C) 2011 Gabor Juhos * * Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o. * * 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. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define DRIVER_NAME "ar933x-uart" #define AR933X_UART_MAX_SCALE 0xff #define AR933X_UART_MAX_STEP 0xffff #define AR933X_UART_MIN_BAUD 300 #define AR933X_UART_MAX_BAUD 3000000 #define AR933X_DUMMY_STATUS_RD 0x01 static struct uart_driver ar933x_uart_driver; struct ar933x_uart_port { struct uart_port port; unsigned int ier; /* shadow Interrupt Enable Register */ unsigned int min_baud; unsigned int max_baud; struct clk *clk; }; static inline bool ar933x_uart_console_enabled(void) { return IS_ENABLED(CONFIG_SERIAL_AR933X_CONSOLE); } static inline unsigned int ar933x_uart_read(struct ar933x_uart_port *up, int offset) { return readl(up->port.membase + offset); } static inline void ar933x_uart_write(struct ar933x_uart_port *up, int offset, unsigned int value) { writel(value, up->port.membase + offset); } static inline void ar933x_uart_rmw(struct ar933x_uart_port *up, unsigned int offset, unsigned int mask, unsigned int val) { unsigned int t; t = ar933x_uart_read(up, offset); t &= ~mask; t |= val; ar933x_uart_write(up, offset, t); } static inline void ar933x_uart_rmw_set(struct ar933x_uart_port *up, unsigned int offset, unsigned int val) { ar933x_uart_rmw(up, offset, 0, val); } static inline void ar933x_uart_rmw_clear(struct ar933x_uart_port *up, unsigned int offset, unsigned int val) { ar933x_uart_rmw(up, offset, val, 0); } static inline void ar933x_uart_start_tx_interrupt(struct ar933x_uart_port *up) { up->ier |= AR933X_UART_INT_TX_EMPTY; ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier); } static inline void ar933x_uart_stop_tx_interrupt(struct ar933x_uart_port *up) { up->ier &= ~AR933X_UART_INT_TX_EMPTY; ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier); } static inline void ar933x_uart_putc(struct ar933x_uart_port *up, int ch) { unsigned int rdata; rdata = ch & AR933X_UART_DATA_TX_RX_MASK; rdata |= AR933X_UART_DATA_TX_CSR; ar933x_uart_write(up, AR933X_UART_DATA_REG, rdata); } static unsigned int ar933x_uart_tx_empty(struct uart_port *port) { struct ar933x_uart_port *up = container_of(port, struct ar933x_uart_port, port); unsigned long flags; unsigned int rdata; spin_lock_irqsave(&up->port.lock, flags); rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG); spin_unlock_irqrestore(&up->port.lock, flags); return (rdata & AR933X_UART_DATA_TX_CSR) ? 0 : TIOCSER_TEMT; } static unsigned int ar933x_uart_get_mctrl(struct uart_port *port) { return TIOCM_CAR; } static void ar933x_uart_set_mctrl(struct uart_port *port, unsigned int mctrl) { } static void ar933x_uart_start_tx(struct uart_port *port) { struct ar933x_uart_port *up = container_of(port, struct ar933x_uart_port, port); ar933x_uart_start_tx_interrupt(up); } static void ar933x_uart_stop_tx(struct uart_port *port) { struct ar933x_uart_port *up = container_of(port, struct ar933x_uart_port, port); ar933x_uart_stop_tx_interrupt(up); } static void ar933x_uart_stop_rx(struct uart_port *port) { struct ar933x_uart_port *up = container_of(port, struct ar933x_uart_port, port); up->ier &= ~AR933X_UART_INT_RX_VALID; ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier); } static void ar933x_uart_break_ctl(struct uart_port *port, int break_state) { struct ar933x_uart_port *up = container_of(port, struct ar933x_uart_port, port); unsigned long flags; spin_lock_irqsave(&up->port.lock, flags); if (break_state == -1) ar933x_uart_rmw_set(up, AR933X_UART_CS_REG, AR933X_UART_CS_TX_BREAK); else ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG, AR933X_UART_CS_TX_BREAK); spin_unlock_irqrestore(&up->port.lock, flags); } /* * baudrate = (clk / (scale + 1)) * (step * (1 / 2^17)) */ static unsigned long ar933x_uart_get_baud(unsigned int clk, unsigned int scale, unsigned int step) { u64 t; u32 div; div = (2 << 16) * (scale + 1); t = clk; t *= step; t += (div / 2); do_div(t, div); return t; } static void ar933x_uart_get_scale_step(unsigned int clk, unsigned int baud, unsigned int *scale, unsigned int *step) { unsigned int tscale; long min_diff; *scale = 0; *step = 0; min_diff = baud; for (tscale = 0; tscale < AR933X_UART_MAX_SCALE; tscale++) { u64 tstep; int diff; tstep = baud * (tscale + 1); tstep *= (2 << 16); do_div(tstep, clk); if (tstep > AR933X_UART_MAX_STEP) break; diff = abs(ar933x_uart_get_baud(clk, tscale, tstep) - baud); if (diff < min_diff) { min_diff = diff; *scale = tscale; *step = tstep; } } } static void ar933x_uart_set_termios(struct uart_port *port, struct ktermios *new, struct ktermios *old) { struct ar933x_uart_port *up = container_of(port, struct ar933x_uart_port, port); unsigned int cs; unsigned long flags; unsigned int baud, scale, step; /* Only CS8 is supported */ new->c_cflag &= ~CSIZE; new->c_cflag |= CS8; /* Only one stop bit is supported */ new->c_cflag &= ~CSTOPB; cs = 0; if (new->c_cflag & PARENB) { if (!(new->c_cflag & PARODD)) cs |= AR933X_UART_CS_PARITY_EVEN; else cs |= AR933X_UART_CS_PARITY_ODD; } else { cs |= AR933X_UART_CS_PARITY_NONE; } /* Mark/space parity is not supported */ new->c_cflag &= ~CMSPAR; baud = uart_get_baud_rate(port, new, old, up->min_baud, up->max_baud); ar933x_uart_get_scale_step(port->uartclk, baud, &scale, &step); /* * Ok, we're now changing the port state. Do it with * interrupts disabled. */ spin_lock_irqsave(&up->port.lock, flags); /* disable the UART */ ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG, AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S); /* Update the per-port timeout. */ uart_update_timeout(port, new->c_cflag, baud); up->port.ignore_status_mask = 0; /* ignore all characters if CREAD is not set */ if ((new->c_cflag & CREAD) == 0) up->port.ignore_status_mask |= AR933X_DUMMY_STATUS_RD; ar933x_uart_write(up, AR933X_UART_CLOCK_REG, scale << AR933X_UART_CLOCK_SCALE_S | step); /* setup configuration register */ ar933x_uart_rmw(up, AR933X_UART_CS_REG, AR933X_UART_CS_PARITY_M, cs); /* enable host interrupt */ ar933x_uart_rmw_set(up, AR933X_UART_CS_REG, AR933X_UART_CS_HOST_INT_EN); /* reenable the UART */ ar933x_uart_rmw(up, AR933X_UART_CS_REG, AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S, AR933X_UART_CS_IF_MODE_DCE << AR933X_UART_CS_IF_MODE_S); spin_unlock_irqrestore(&up->port.lock, flags); if (tty_termios_baud_rate(new)) tty_termios_encode_baud_rate(new, baud, baud); } static void ar933x_uart_rx_chars(struct ar933x_uart_port *up) { struct tty_port *port = &up->port.state->port; int max_count = 256; do { unsigned int rdata; unsigned char ch; rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG); if ((rdata & AR933X_UART_DATA_RX_CSR) == 0) break; /* remove the character from the FIFO */ ar933x_uart_write(up, AR933X_UART_DATA_REG, AR933X_UART_DATA_RX_CSR); up->port.icount.rx++; ch = rdata & AR933X_UART_DATA_TX_RX_MASK; if (uart_handle_sysrq_char(&up->port, ch)) continue; if ((up->port.ignore_status_mask & AR933X_DUMMY_STATUS_RD) == 0) tty_insert_flip_char(port, ch, TTY_NORMAL); } while (max_count-- > 0); spin_unlock(&up->port.lock); tty_flip_buffer_push(port); spin_lock(&up->port.lock); } static void ar933x_uart_tx_chars(struct ar933x_uart_port *up) { struct circ_buf *xmit = &up->port.state->xmit; int count; if (uart_tx_stopped(&up->port)) return; count = up->port.fifosize; do { unsigned int rdata; rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG); if ((rdata & AR933X_UART_DATA_TX_CSR) == 0) break; if (up->port.x_char) { ar933x_uart_putc(up, up->port.x_char); up->port.icount.tx++; up->port.x_char = 0; continue; } if (uart_circ_empty(xmit)) break; ar933x_uart_putc(up, xmit->buf[xmit->tail]); xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); up->port.icount.tx++; } while (--count > 0); if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) uart_write_wakeup(&up->port); if (!uart_circ_empty(xmit)) ar933x_uart_start_tx_interrupt(up); } static irqreturn_t ar933x_uart_interrupt(int irq, void *dev_id) { struct ar933x_uart_port *up = dev_id; unsigned int status; status = ar933x_uart_read(up, AR933X_UART_CS_REG); if ((status & AR933X_UART_CS_HOST_INT) == 0) return IRQ_NONE; spin_lock(&up->port.lock); status = ar933x_uart_read(up, AR933X_UART_INT_REG); status &= ar933x_uart_read(up, AR933X_UART_INT_EN_REG); if (status & AR933X_UART_INT_RX_VALID) { ar933x_uart_write(up, AR933X_UART_INT_REG, AR933X_UART_INT_RX_VALID); ar933x_uart_rx_chars(up); } if (status & AR933X_UART_INT_TX_EMPTY) { ar933x_uart_write(up, AR933X_UART_INT_REG, AR933X_UART_INT_TX_EMPTY); ar933x_uart_stop_tx_interrupt(up); ar933x_uart_tx_chars(up); } spin_unlock(&up->port.lock); return IRQ_HANDLED; } static int ar933x_uart_startup(struct uart_port *port) { struct ar933x_uart_port *up = container_of(port, struct ar933x_uart_port, port); unsigned long flags; int ret; ret = request_irq(up->port.irq, ar933x_uart_interrupt, up->port.irqflags, dev_name(up->port.dev), up); if (ret) return ret; spin_lock_irqsave(&up->port.lock, flags); /* Enable HOST interrupts */ ar933x_uart_rmw_set(up, AR933X_UART_CS_REG, AR933X_UART_CS_HOST_INT_EN); /* Enable RX interrupts */ up->ier = AR933X_UART_INT_RX_VALID; ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier); spin_unlock_irqrestore(&up->port.lock, flags); return 0; } static void ar933x_uart_shutdown(struct uart_port *port) { struct ar933x_uart_port *up = container_of(port, struct ar933x_uart_port, port); /* Disable all interrupts */ up->ier = 0; ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier); /* Disable break condition */ ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG, AR933X_UART_CS_TX_BREAK); free_irq(up->port.irq, up); } static const char *ar933x_uart_type(struct uart_port *port) { return (port->type == PORT_AR933X) ? "AR933X UART" : NULL; } static void ar933x_uart_release_port(struct uart_port *port) { /* Nothing to release ... */ } static int ar933x_uart_request_port(struct uart_port *port) { /* UARTs always present */ return 0; } static void ar933x_uart_config_port(struct uart_port *port, int flags) { if (flags & UART_CONFIG_TYPE) port->type = PORT_AR933X; } static int ar933x_uart_verify_port(struct uart_port *port, struct serial_struct *ser) { struct ar933x_uart_port *up = container_of(port, struct ar933x_uart_port, port); if (ser->type != PORT_UNKNOWN && ser->type != PORT_AR933X) return -EINVAL; if (ser->irq < 0 || ser->irq >= NR_IRQS) return -EINVAL; if (ser->baud_base < up->min_baud || ser->baud_base > up->max_baud) return -EINVAL; return 0; } static const struct uart_ops ar933x_uart_ops = { .tx_empty = ar933x_uart_tx_empty, .set_mctrl = ar933x_uart_set_mctrl, .get_mctrl = ar933x_uart_get_mctrl, .stop_tx = ar933x_uart_stop_tx, .start_tx = ar933x_uart_start_tx, .stop_rx = ar933x_uart_stop_rx, .break_ctl = ar933x_uart_break_ctl, .startup = ar933x_uart_startup, .shutdown = ar933x_uart_shutdown, .set_termios = ar933x_uart_set_termios, .type = ar933x_uart_type, .release_port = ar933x_uart_release_port, .request_port = ar933x_uart_request_port, .config_port = ar933x_uart_config_port, .verify_port = ar933x_uart_verify_port, }; static struct ar933x_uart_port * ar933x_console_ports[CONFIG_SERIAL_AR933X_NR_UARTS]; static void ar933x_uart_wait_xmitr(struct ar933x_uart_port *up) { unsigned int status; unsigned int timeout = 60000; /* Wait up to 60ms for the character(s) to be sent. */ do { status = ar933x_uart_read(up, AR933X_UART_DATA_REG); if (--timeout == 0) break; udelay(1); } while ((status & AR933X_UART_DATA_TX_CSR) == 0); } static void ar933x_uart_console_putchar(struct uart_port *port, int ch) { struct ar933x_uart_port *up = container_of(port, struct ar933x_uart_port, port); ar933x_uart_wait_xmitr(up); ar933x_uart_putc(up, ch); } static void ar933x_uart_console_write(struct console *co, const char *s, unsigned int count) { struct ar933x_uart_port *up = ar933x_console_ports[co->index]; unsigned long flags; unsigned int int_en; int locked = 1; local_irq_save(flags); if (up->port.sysrq) locked = 0; else if (oops_in_progress) locked = spin_trylock(&up->port.lock); else spin_lock(&up->port.lock); /* * First save the IER then disable the interrupts */ int_en = ar933x_uart_read(up, AR933X_UART_INT_EN_REG); ar933x_uart_write(up, AR933X_UART_INT_EN_REG, 0); uart_console_write(&up->port, s, count, ar933x_uart_console_putchar); /* * Finally, wait for transmitter to become empty * and restore the IER */ ar933x_uart_wait_xmitr(up); ar933x_uart_write(up, AR933X_UART_INT_EN_REG, int_en); ar933x_uart_write(up, AR933X_UART_INT_REG, AR933X_UART_INT_ALLINTS); if (locked) spin_unlock(&up->port.lock); local_irq_restore(flags); } static int ar933x_uart_console_setup(struct console *co, char *options) { struct ar933x_uart_port *up; int baud = 115200; int bits = 8; int parity = 'n'; int flow = 'n'; if (co->index < 0 || co->index >= CONFIG_SERIAL_AR933X_NR_UARTS) return -EINVAL; up = ar933x_console_ports[co->index]; if (!up) return -ENODEV; if (options) uart_parse_options(options, &baud, &parity, &bits, &flow); return uart_set_options(&up->port, co, baud, parity, bits, flow); } static struct console ar933x_uart_console = { .name = "ttyATH", .write = ar933x_uart_console_write, .device = uart_console_device, .setup = ar933x_uart_console_setup, .flags = CON_PRINTBUFFER, .index = -1, .data = &ar933x_uart_driver, }; static void ar933x_uart_add_console_port(struct ar933x_uart_port *up) { if (!ar933x_uart_console_enabled()) return; ar933x_console_ports[up->port.line] = up; } static struct uart_driver ar933x_uart_driver = { .owner = THIS_MODULE, .driver_name = DRIVER_NAME, .dev_name = "ttyATH", .nr = CONFIG_SERIAL_AR933X_NR_UARTS, .cons = NULL, /* filled in runtime */ }; static int ar933x_uart_probe(struct platform_device *pdev) { struct ar933x_uart_port *up; struct uart_port *port; struct resource *mem_res; struct resource *irq_res; struct device_node *np; unsigned int baud; int id; int ret; np = pdev->dev.of_node; if (IS_ENABLED(CONFIG_OF) && np) { id = of_alias_get_id(np, "serial"); if (id < 0) { dev_err(&pdev->dev, "unable to get alias id, err=%d\n", id); return id; } } else { id = pdev->id; if (id == -1) id = 0; } if (id >= CONFIG_SERIAL_AR933X_NR_UARTS) return -EINVAL; irq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 0); if (!irq_res) { dev_err(&pdev->dev, "no IRQ resource\n"); return -EINVAL; } up = devm_kzalloc(&pdev->dev, sizeof(struct ar933x_uart_port), GFP_KERNEL); if (!up) return -ENOMEM; up->clk = devm_clk_get(&pdev->dev, "uart"); if (IS_ERR(up->clk)) { dev_err(&pdev->dev, "unable to get UART clock\n"); return PTR_ERR(up->clk); } port = &up->port; mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0); port->membase = devm_ioremap_resource(&pdev->dev, mem_res); if (IS_ERR(port->membase)) return PTR_ERR(port->membase); ret = clk_prepare_enable(up->clk); if (ret) return ret; port->uartclk = clk_get_rate(up->clk); if (!port->uartclk) { ret = -EINVAL; goto err_disable_clk; } port->mapbase = mem_res->start; port->line = id; port->irq = irq_res->start; port->dev = &pdev->dev; port->type = PORT_AR933X; port->iotype = UPIO_MEM32; port->regshift = 2; port->fifosize = AR933X_UART_FIFO_SIZE; port->ops = &ar933x_uart_ops; baud = ar933x_uart_get_baud(port->uartclk, AR933X_UART_MAX_SCALE, 1); up->min_baud = max_t(unsigned int, baud, AR933X_UART_MIN_BAUD); baud = ar933x_uart_get_baud(port->uartclk, 0, AR933X_UART_MAX_STEP); up->max_baud = min_t(unsigned int, baud, AR933X_UART_MAX_BAUD); ar933x_uart_add_console_port(up); ret = uart_add_one_port(&ar933x_uart_driver, &up->port); if (ret) goto err_disable_clk; platform_set_drvdata(pdev, up); return 0; err_disable_clk: clk_disable_unprepare(up->clk); return ret; } static int ar933x_uart_remove(struct platform_device *pdev) { struct ar933x_uart_port *up; up = platform_get_drvdata(pdev); if (up) { uart_remove_one_port(&ar933x_uart_driver, &up->port); clk_disable_unprepare(up->clk); } return 0; } #ifdef CONFIG_OF static const struct of_device_id ar933x_uart_of_ids[] = { { .compatible = "qca,ar9330-uart" }, {}, }; MODULE_DEVICE_TABLE(of, ar933x_uart_of_ids); #endif static struct platform_driver ar933x_uart_platform_driver = { .probe = ar933x_uart_probe, .remove = ar933x_uart_remove, .driver = { .name = DRIVER_NAME, .of_match_table = of_match_ptr(ar933x_uart_of_ids), }, }; static int __init ar933x_uart_init(void) { int ret; if (ar933x_uart_console_enabled()) ar933x_uart_driver.cons = &ar933x_uart_console; ret = uart_register_driver(&ar933x_uart_driver); if (ret) goto err_out; ret = platform_driver_register(&ar933x_uart_platform_driver); if (ret) goto err_unregister_uart_driver; return 0; err_unregister_uart_driver: uart_unregister_driver(&ar933x_uart_driver); err_out: return ret; } static void __exit ar933x_uart_exit(void) { platform_driver_unregister(&ar933x_uart_platform_driver); uart_unregister_driver(&ar933x_uart_driver); } module_init(ar933x_uart_init); module_exit(ar933x_uart_exit); MODULE_DESCRIPTION("Atheros AR933X UART driver"); MODULE_AUTHOR("Gabor Juhos "); MODULE_LICENSE("GPL v2"); MODULE_ALIAS("platform:" DRIVER_NAME);