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1// SPDX-License-Identifier: GPL-2.0+2/*3 * Driver for Conexant Digicolor serial ports (USART)4 *5 * Author: Baruch Siach <baruch@tkos.co.il>6 *7 * Copyright (C) 2014 Paradox Innovation Ltd.8 */9 10#include <linux/module.h>11#include <linux/console.h>12#include <linux/serial_core.h>13#include <linux/serial.h>14#include <linux/clk.h>15#include <linux/io.h>16#include <linux/tty.h>17#include <linux/tty_flip.h>18#include <linux/of.h>19#include <linux/platform_device.h>20#include <linux/workqueue.h>21 22#define UA_ENABLE 0x0023#define UA_ENABLE_ENABLE BIT(0)24 25#define UA_CONTROL 0x0126#define UA_CONTROL_RX_ENABLE BIT(0)27#define UA_CONTROL_TX_ENABLE BIT(1)28#define UA_CONTROL_SOFT_RESET BIT(2)29 30#define UA_STATUS 0x0231#define UA_STATUS_PARITY_ERR BIT(0)32#define UA_STATUS_FRAME_ERR BIT(1)33#define UA_STATUS_OVERRUN_ERR BIT(2)34#define UA_STATUS_TX_READY BIT(6)35 36#define UA_CONFIG 0x0337#define UA_CONFIG_CHAR_LEN BIT(0)38#define UA_CONFIG_STOP_BITS BIT(1)39#define UA_CONFIG_PARITY BIT(2)40#define UA_CONFIG_ODD_PARITY BIT(4)41 42#define UA_EMI_REC 0x0443 44#define UA_HBAUD_LO 0x0845#define UA_HBAUD_HI 0x0946 47#define UA_STATUS_FIFO 0x0a48#define UA_STATUS_FIFO_RX_EMPTY BIT(2)49#define UA_STATUS_FIFO_RX_INT_ALMOST BIT(3)50#define UA_STATUS_FIFO_TX_FULL BIT(4)51#define UA_STATUS_FIFO_TX_INT_ALMOST BIT(7)52 53#define UA_CONFIG_FIFO 0x0b54#define UA_CONFIG_FIFO_RX_THRESH 755#define UA_CONFIG_FIFO_RX_FIFO_MODE BIT(3)56#define UA_CONFIG_FIFO_TX_FIFO_MODE BIT(7)57 58#define UA_INTFLAG_CLEAR 0x1c59#define UA_INTFLAG_SET 0x1d60#define UA_INT_ENABLE 0x1e61#define UA_INT_STATUS 0x1f62 63#define UA_INT_TX BIT(0)64#define UA_INT_RX BIT(1)65 66#define DIGICOLOR_USART_NR 367 68/*69 * We use the 16 bytes hardware FIFO to buffer Rx traffic. Rx interrupt is70 * only produced when the FIFO is filled more than a certain configurable71 * threshold. Unfortunately, there is no way to set this threshold below half72 * FIFO. This means that we must periodically poll the FIFO status register to73 * see whether there are waiting Rx bytes.74 */75 76struct digicolor_port {77 struct uart_port port;78 struct delayed_work rx_poll_work;79};80 81static struct uart_port *digicolor_ports[DIGICOLOR_USART_NR];82 83static bool digicolor_uart_tx_full(struct uart_port *port)84{85 return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &86 UA_STATUS_FIFO_TX_FULL);87}88 89static bool digicolor_uart_rx_empty(struct uart_port *port)90{91 return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &92 UA_STATUS_FIFO_RX_EMPTY);93}94 95static void digicolor_uart_stop_tx(struct uart_port *port)96{97 u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);98 99 int_enable &= ~UA_INT_TX;100 writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);101}102 103static void digicolor_uart_start_tx(struct uart_port *port)104{105 u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);106 107 int_enable |= UA_INT_TX;108 writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);109}110 111static void digicolor_uart_stop_rx(struct uart_port *port)112{113 u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);114 115 int_enable &= ~UA_INT_RX;116 writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);117}118 119static void digicolor_rx_poll(struct work_struct *work)120{121 struct digicolor_port *dp =122 container_of(to_delayed_work(work),123 struct digicolor_port, rx_poll_work);124 125 if (!digicolor_uart_rx_empty(&dp->port))126 /* force RX interrupt */127 writeb_relaxed(UA_INT_RX, dp->port.membase + UA_INTFLAG_SET);128 129 schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));130}131 132static void digicolor_uart_rx(struct uart_port *port)133{134 unsigned long flags;135 136 uart_port_lock_irqsave(port, &flags);137 138 while (1) {139 u8 status, ch, ch_flag;140 141 if (digicolor_uart_rx_empty(port))142 break;143 144 ch = readb_relaxed(port->membase + UA_EMI_REC);145 status = readb_relaxed(port->membase + UA_STATUS);146 147 port->icount.rx++;148 ch_flag = TTY_NORMAL;149 150 if (status) {151 if (status & UA_STATUS_PARITY_ERR)152 port->icount.parity++;153 else if (status & UA_STATUS_FRAME_ERR)154 port->icount.frame++;155 else if (status & UA_STATUS_OVERRUN_ERR)156 port->icount.overrun++;157 158 status &= port->read_status_mask;159 160 if (status & UA_STATUS_PARITY_ERR)161 ch_flag = TTY_PARITY;162 else if (status & UA_STATUS_FRAME_ERR)163 ch_flag = TTY_FRAME;164 else if (status & UA_STATUS_OVERRUN_ERR)165 ch_flag = TTY_OVERRUN;166 }167 168 if (status & port->ignore_status_mask)169 continue;170 171 uart_insert_char(port, status, UA_STATUS_OVERRUN_ERR, ch,172 ch_flag);173 }174 175 uart_port_unlock_irqrestore(port, flags);176 177 tty_flip_buffer_push(&port->state->port);178}179 180static void digicolor_uart_tx(struct uart_port *port)181{182 struct tty_port *tport = &port->state->port;183 unsigned long flags;184 unsigned char c;185 186 if (digicolor_uart_tx_full(port))187 return;188 189 uart_port_lock_irqsave(port, &flags);190 191 if (port->x_char) {192 writeb_relaxed(port->x_char, port->membase + UA_EMI_REC);193 port->icount.tx++;194 port->x_char = 0;195 goto out;196 }197 198 if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)) {199 digicolor_uart_stop_tx(port);200 goto out;201 }202 203 while (uart_fifo_get(port, &c)) {204 writeb(c, port->membase + UA_EMI_REC);205 206 if (digicolor_uart_tx_full(port))207 break;208 }209 210 if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)211 uart_write_wakeup(port);212 213out:214 uart_port_unlock_irqrestore(port, flags);215}216 217static irqreturn_t digicolor_uart_int(int irq, void *dev_id)218{219 struct uart_port *port = dev_id;220 u8 int_status = readb_relaxed(port->membase + UA_INT_STATUS);221 222 writeb_relaxed(UA_INT_RX | UA_INT_TX,223 port->membase + UA_INTFLAG_CLEAR);224 225 if (int_status & UA_INT_RX)226 digicolor_uart_rx(port);227 if (int_status & UA_INT_TX)228 digicolor_uart_tx(port);229 230 return IRQ_HANDLED;231}232 233static unsigned int digicolor_uart_tx_empty(struct uart_port *port)234{235 u8 status = readb_relaxed(port->membase + UA_STATUS);236 237 return (status & UA_STATUS_TX_READY) ? TIOCSER_TEMT : 0;238}239 240static unsigned int digicolor_uart_get_mctrl(struct uart_port *port)241{242 return TIOCM_CTS;243}244 245static void digicolor_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)246{247}248 249static void digicolor_uart_break_ctl(struct uart_port *port, int state)250{251}252 253static int digicolor_uart_startup(struct uart_port *port)254{255 struct digicolor_port *dp =256 container_of(port, struct digicolor_port, port);257 258 writeb_relaxed(UA_ENABLE_ENABLE, port->membase + UA_ENABLE);259 writeb_relaxed(UA_CONTROL_SOFT_RESET, port->membase + UA_CONTROL);260 writeb_relaxed(0, port->membase + UA_CONTROL);261 262 writeb_relaxed(UA_CONFIG_FIFO_RX_FIFO_MODE263 | UA_CONFIG_FIFO_TX_FIFO_MODE | UA_CONFIG_FIFO_RX_THRESH,264 port->membase + UA_CONFIG_FIFO);265 writeb_relaxed(UA_STATUS_FIFO_RX_INT_ALMOST,266 port->membase + UA_STATUS_FIFO);267 writeb_relaxed(UA_CONTROL_RX_ENABLE | UA_CONTROL_TX_ENABLE,268 port->membase + UA_CONTROL);269 writeb_relaxed(UA_INT_TX | UA_INT_RX,270 port->membase + UA_INT_ENABLE);271 272 schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));273 274 return 0;275}276 277static void digicolor_uart_shutdown(struct uart_port *port)278{279 struct digicolor_port *dp =280 container_of(port, struct digicolor_port, port);281 282 writeb_relaxed(0, port->membase + UA_ENABLE);283 cancel_delayed_work_sync(&dp->rx_poll_work);284}285 286static void digicolor_uart_set_termios(struct uart_port *port,287 struct ktermios *termios,288 const struct ktermios *old)289{290 unsigned int baud, divisor;291 u8 config = 0;292 unsigned long flags;293 294 /* Mask termios capabilities we don't support */295 termios->c_cflag &= ~CMSPAR;296 termios->c_iflag &= ~(BRKINT | IGNBRK);297 298 /* Limit baud rates so that we don't need the fractional divider */299 baud = uart_get_baud_rate(port, termios, old,300 port->uartclk / (0x10000*16),301 port->uartclk / 256);302 divisor = uart_get_divisor(port, baud) - 1;303 304 switch (termios->c_cflag & CSIZE) {305 case CS7:306 break;307 case CS8:308 default:309 config |= UA_CONFIG_CHAR_LEN;310 termios->c_cflag &= ~CSIZE;311 termios->c_cflag |= CS8;312 break;313 }314 315 if (termios->c_cflag & CSTOPB)316 config |= UA_CONFIG_STOP_BITS;317 318 if (termios->c_cflag & PARENB) {319 config |= UA_CONFIG_PARITY;320 if (termios->c_cflag & PARODD)321 config |= UA_CONFIG_ODD_PARITY;322 }323 324 /* Set read status mask */325 port->read_status_mask = UA_STATUS_OVERRUN_ERR;326 if (termios->c_iflag & INPCK)327 port->read_status_mask |= UA_STATUS_PARITY_ERR328 | UA_STATUS_FRAME_ERR;329 330 /* Set status ignore mask */331 port->ignore_status_mask = 0;332 if (!(termios->c_cflag & CREAD))333 port->ignore_status_mask |= UA_STATUS_OVERRUN_ERR334 | UA_STATUS_PARITY_ERR | UA_STATUS_FRAME_ERR;335 336 uart_port_lock_irqsave(port, &flags);337 338 uart_update_timeout(port, termios->c_cflag, baud);339 340 writeb_relaxed(config, port->membase + UA_CONFIG);341 writeb_relaxed(divisor & 0xff, port->membase + UA_HBAUD_LO);342 writeb_relaxed(divisor >> 8, port->membase + UA_HBAUD_HI);343 344 uart_port_unlock_irqrestore(port, flags);345}346 347static const char *digicolor_uart_type(struct uart_port *port)348{349 return (port->type == PORT_DIGICOLOR) ? "DIGICOLOR USART" : NULL;350}351 352static void digicolor_uart_config_port(struct uart_port *port, int flags)353{354 if (flags & UART_CONFIG_TYPE)355 port->type = PORT_DIGICOLOR;356}357 358static void digicolor_uart_release_port(struct uart_port *port)359{360}361 362static int digicolor_uart_request_port(struct uart_port *port)363{364 return 0;365}366 367static const struct uart_ops digicolor_uart_ops = {368 .tx_empty = digicolor_uart_tx_empty,369 .set_mctrl = digicolor_uart_set_mctrl,370 .get_mctrl = digicolor_uart_get_mctrl,371 .stop_tx = digicolor_uart_stop_tx,372 .start_tx = digicolor_uart_start_tx,373 .stop_rx = digicolor_uart_stop_rx,374 .break_ctl = digicolor_uart_break_ctl,375 .startup = digicolor_uart_startup,376 .shutdown = digicolor_uart_shutdown,377 .set_termios = digicolor_uart_set_termios,378 .type = digicolor_uart_type,379 .config_port = digicolor_uart_config_port,380 .release_port = digicolor_uart_release_port,381 .request_port = digicolor_uart_request_port,382};383 384static void digicolor_uart_console_putchar(struct uart_port *port, unsigned char ch)385{386 while (digicolor_uart_tx_full(port))387 cpu_relax();388 389 writeb_relaxed(ch, port->membase + UA_EMI_REC);390}391 392static void digicolor_uart_console_write(struct console *co, const char *c,393 unsigned n)394{395 struct uart_port *port = digicolor_ports[co->index];396 u8 status;397 unsigned long flags;398 int locked = 1;399 400 if (oops_in_progress)401 locked = uart_port_trylock_irqsave(port, &flags);402 else403 uart_port_lock_irqsave(port, &flags);404 405 uart_console_write(port, c, n, digicolor_uart_console_putchar);406 407 if (locked)408 uart_port_unlock_irqrestore(port, flags);409 410 /* Wait for transmitter to become empty */411 do {412 status = readb_relaxed(port->membase + UA_STATUS);413 } while ((status & UA_STATUS_TX_READY) == 0);414}415 416static int digicolor_uart_console_setup(struct console *co, char *options)417{418 int baud = 115200, bits = 8, parity = 'n', flow = 'n';419 struct uart_port *port;420 421 if (co->index < 0 || co->index >= DIGICOLOR_USART_NR)422 return -EINVAL;423 424 port = digicolor_ports[co->index];425 if (!port)426 return -ENODEV;427 428 if (options)429 uart_parse_options(options, &baud, &parity, &bits, &flow);430 431 return uart_set_options(port, co, baud, parity, bits, flow);432}433 434static struct console digicolor_console = {435 .name = "ttyS",436 .device = uart_console_device,437 .write = digicolor_uart_console_write,438 .setup = digicolor_uart_console_setup,439 .flags = CON_PRINTBUFFER,440 .index = -1,441};442 443static struct uart_driver digicolor_uart = {444 .driver_name = "digicolor-usart",445 .dev_name = "ttyS",446 .nr = DIGICOLOR_USART_NR,447};448 449static int digicolor_uart_probe(struct platform_device *pdev)450{451 struct device_node *np = pdev->dev.of_node;452 int irq, ret, index;453 struct digicolor_port *dp;454 struct resource *res;455 struct clk *uart_clk;456 457 if (!np) {458 dev_err(&pdev->dev, "Missing device tree node\n");459 return -ENXIO;460 }461 462 index = of_alias_get_id(np, "serial");463 if (index < 0 || index >= DIGICOLOR_USART_NR)464 return -EINVAL;465 466 dp = devm_kzalloc(&pdev->dev, sizeof(*dp), GFP_KERNEL);467 if (!dp)468 return -ENOMEM;469 470 uart_clk = devm_clk_get(&pdev->dev, NULL);471 if (IS_ERR(uart_clk))472 return PTR_ERR(uart_clk);473 474 dp->port.membase = devm_platform_get_and_ioremap_resource(pdev, 0, &res);475 if (IS_ERR(dp->port.membase))476 return PTR_ERR(dp->port.membase);477 dp->port.mapbase = res->start;478 479 irq = platform_get_irq(pdev, 0);480 if (irq < 0)481 return irq;482 dp->port.irq = irq;483 484 dp->port.iotype = UPIO_MEM;485 dp->port.uartclk = clk_get_rate(uart_clk);486 dp->port.fifosize = 16;487 dp->port.dev = &pdev->dev;488 dp->port.ops = &digicolor_uart_ops;489 dp->port.line = index;490 dp->port.type = PORT_DIGICOLOR;491 spin_lock_init(&dp->port.lock);492 493 digicolor_ports[index] = &dp->port;494 platform_set_drvdata(pdev, &dp->port);495 496 INIT_DELAYED_WORK(&dp->rx_poll_work, digicolor_rx_poll);497 498 ret = devm_request_irq(&pdev->dev, dp->port.irq, digicolor_uart_int, 0,499 dev_name(&pdev->dev), &dp->port);500 if (ret)501 return ret;502 503 return uart_add_one_port(&digicolor_uart, &dp->port);504}505 506static void digicolor_uart_remove(struct platform_device *pdev)507{508 struct uart_port *port = platform_get_drvdata(pdev);509 510 uart_remove_one_port(&digicolor_uart, port);511}512 513static const struct of_device_id digicolor_uart_dt_ids[] = {514 { .compatible = "cnxt,cx92755-usart", },515 { }516};517MODULE_DEVICE_TABLE(of, digicolor_uart_dt_ids);518 519static struct platform_driver digicolor_uart_platform = {520 .driver = {521 .name = "digicolor-usart",522 .of_match_table = of_match_ptr(digicolor_uart_dt_ids),523 },524 .probe = digicolor_uart_probe,525 .remove_new = digicolor_uart_remove,526};527 528static int __init digicolor_uart_init(void)529{530 int ret;531 532 if (IS_ENABLED(CONFIG_SERIAL_CONEXANT_DIGICOLOR_CONSOLE)) {533 digicolor_uart.cons = &digicolor_console;534 digicolor_console.data = &digicolor_uart;535 }536 537 ret = uart_register_driver(&digicolor_uart);538 if (ret)539 return ret;540 541 ret = platform_driver_register(&digicolor_uart_platform);542 if (ret)543 uart_unregister_driver(&digicolor_uart);544 545 return ret;546}547module_init(digicolor_uart_init);548 549static void __exit digicolor_uart_exit(void)550{551 platform_driver_unregister(&digicolor_uart_platform);552 uart_unregister_driver(&digicolor_uart);553}554module_exit(digicolor_uart_exit);555 556MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");557MODULE_DESCRIPTION("Conexant Digicolor USART serial driver");558MODULE_LICENSE("GPL");559