1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Mediatek 8250 driver. 4 * 5 * Copyright (c) 2014 MundoReader S.L. 6 * Author: Matthias Brugger <matthias.bgg@gmail.com> 7 */ 8 #include <linux/clk.h> 9 #include <linux/io.h> 10 #include <linux/module.h> 11 #include <linux/of_irq.h> 12 #include <linux/of_platform.h> 13 #include <linux/platform_device.h> 14 #include <linux/pm_runtime.h> 15 #include <linux/serial_8250.h> 16 #include <linux/serial_reg.h> 17 #include <linux/console.h> 18 #include <linux/dma-mapping.h> 19 #include <linux/tty.h> 20 #include <linux/tty_flip.h> 21 22 #include "8250.h" 23 24 #define UART_MTK_HIGHS 0x09 /* Highspeed register */ 25 #define UART_MTK_SAMPLE_COUNT 0x0a /* Sample count register */ 26 #define UART_MTK_SAMPLE_POINT 0x0b /* Sample point register */ 27 #define MTK_UART_RATE_FIX 0x0d /* UART Rate Fix Register */ 28 29 #define MTK_UART_DMA_EN 0x13 /* DMA Enable register */ 30 #define MTK_UART_DMA_EN_TX 0x2 31 #define MTK_UART_DMA_EN_RX 0x5 32 33 #define MTK_UART_TX_SIZE UART_XMIT_SIZE 34 #define MTK_UART_RX_SIZE 0x8000 35 #define MTK_UART_TX_TRIGGER 1 36 #define MTK_UART_RX_TRIGGER MTK_UART_RX_SIZE 37 38 #ifdef CONFIG_SERIAL_8250_DMA 39 enum dma_rx_status { 40 DMA_RX_START = 0, 41 DMA_RX_RUNNING = 1, 42 DMA_RX_SHUTDOWN = 2, 43 }; 44 #endif 45 46 struct mtk8250_data { 47 int line; 48 unsigned int rx_pos; 49 struct clk *uart_clk; 50 struct clk *bus_clk; 51 struct uart_8250_dma *dma; 52 #ifdef CONFIG_SERIAL_8250_DMA 53 enum dma_rx_status rx_status; 54 #endif 55 }; 56 57 #ifdef CONFIG_SERIAL_8250_DMA 58 static void mtk8250_rx_dma(struct uart_8250_port *up); 59 60 static void mtk8250_dma_rx_complete(void *param) 61 { 62 struct uart_8250_port *up = param; 63 struct uart_8250_dma *dma = up->dma; 64 struct mtk8250_data *data = up->port.private_data; 65 struct tty_port *tty_port = &up->port.state->port; 66 struct dma_tx_state state; 67 unsigned char *ptr; 68 int copied; 69 70 dma_sync_single_for_cpu(dma->rxchan->device->dev, dma->rx_addr, 71 dma->rx_size, DMA_FROM_DEVICE); 72 73 dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state); 74 75 if (data->rx_status == DMA_RX_SHUTDOWN) 76 return; 77 78 if ((data->rx_pos + state.residue) <= dma->rx_size) { 79 ptr = (unsigned char *)(data->rx_pos + dma->rx_buf); 80 copied = tty_insert_flip_string(tty_port, ptr, state.residue); 81 } else { 82 ptr = (unsigned char *)(data->rx_pos + dma->rx_buf); 83 copied = tty_insert_flip_string(tty_port, ptr, 84 dma->rx_size - data->rx_pos); 85 ptr = (unsigned char *)(dma->rx_buf); 86 copied += tty_insert_flip_string(tty_port, ptr, 87 data->rx_pos + state.residue - dma->rx_size); 88 } 89 up->port.icount.rx += copied; 90 91 tty_flip_buffer_push(tty_port); 92 93 mtk8250_rx_dma(up); 94 } 95 96 static void mtk8250_rx_dma(struct uart_8250_port *up) 97 { 98 struct uart_8250_dma *dma = up->dma; 99 struct mtk8250_data *data = up->port.private_data; 100 struct dma_async_tx_descriptor *desc; 101 struct dma_tx_state state; 102 103 desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr, 104 dma->rx_size, DMA_DEV_TO_MEM, 105 DMA_PREP_INTERRUPT | DMA_CTRL_ACK); 106 if (!desc) { 107 pr_err("failed to prepare rx slave single\n"); 108 return; 109 } 110 111 desc->callback = mtk8250_dma_rx_complete; 112 desc->callback_param = up; 113 114 dma->rx_cookie = dmaengine_submit(desc); 115 116 dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state); 117 data->rx_pos = state.residue; 118 119 dma_sync_single_for_device(dma->rxchan->device->dev, dma->rx_addr, 120 dma->rx_size, DMA_FROM_DEVICE); 121 122 dma_async_issue_pending(dma->rxchan); 123 } 124 125 static void mtk8250_dma_enable(struct uart_8250_port *up) 126 { 127 struct uart_8250_dma *dma = up->dma; 128 struct mtk8250_data *data = up->port.private_data; 129 int lcr = serial_in(up, UART_LCR); 130 131 if (data->rx_status != DMA_RX_START) 132 return; 133 134 dma->rxconf.direction = DMA_DEV_TO_MEM; 135 dma->rxconf.src_addr_width = dma->rx_size / 1024; 136 dma->rxconf.src_addr = dma->rx_addr; 137 138 dma->txconf.direction = DMA_MEM_TO_DEV; 139 dma->txconf.dst_addr_width = MTK_UART_TX_SIZE / 1024; 140 dma->txconf.dst_addr = dma->tx_addr; 141 142 serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_RCVR | 143 UART_FCR_CLEAR_XMIT); 144 serial_out(up, MTK_UART_DMA_EN, 145 MTK_UART_DMA_EN_RX | MTK_UART_DMA_EN_TX); 146 147 serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B); 148 serial_out(up, UART_EFR, UART_EFR_ECB); 149 serial_out(up, UART_LCR, lcr); 150 151 if (dmaengine_slave_config(dma->rxchan, &dma->rxconf) != 0) 152 pr_err("failed to configure rx dma channel\n"); 153 if (dmaengine_slave_config(dma->txchan, &dma->txconf) != 0) 154 pr_err("failed to configure tx dma channel\n"); 155 156 data->rx_status = DMA_RX_RUNNING; 157 data->rx_pos = 0; 158 mtk8250_rx_dma(up); 159 } 160 #endif 161 162 static int mtk8250_startup(struct uart_port *port) 163 { 164 #ifdef CONFIG_SERIAL_8250_DMA 165 struct uart_8250_port *up = up_to_u8250p(port); 166 struct mtk8250_data *data = port->private_data; 167 168 /* disable DMA for console */ 169 if (uart_console(port)) 170 up->dma = NULL; 171 172 if (up->dma) { 173 data->rx_status = DMA_RX_START; 174 uart_circ_clear(&port->state->xmit); 175 } 176 #endif 177 memset(&port->icount, 0, sizeof(port->icount)); 178 179 return serial8250_do_startup(port); 180 } 181 182 static void mtk8250_shutdown(struct uart_port *port) 183 { 184 #ifdef CONFIG_SERIAL_8250_DMA 185 struct uart_8250_port *up = up_to_u8250p(port); 186 struct mtk8250_data *data = port->private_data; 187 188 if (up->dma) 189 data->rx_status = DMA_RX_SHUTDOWN; 190 #endif 191 192 return serial8250_do_shutdown(port); 193 } 194 195 static void 196 mtk8250_set_termios(struct uart_port *port, struct ktermios *termios, 197 struct ktermios *old) 198 { 199 struct uart_8250_port *up = up_to_u8250p(port); 200 unsigned long flags; 201 unsigned int baud, quot; 202 203 #ifdef CONFIG_SERIAL_8250_DMA 204 if (up->dma) { 205 if (uart_console(port)) { 206 devm_kfree(up->port.dev, up->dma); 207 up->dma = NULL; 208 } else { 209 mtk8250_dma_enable(up); 210 } 211 } 212 #endif 213 214 serial8250_do_set_termios(port, termios, old); 215 216 /* 217 * Mediatek UARTs use an extra highspeed register (UART_MTK_HIGHS) 218 * 219 * We need to recalcualte the quot register, as the claculation depends 220 * on the vaule in the highspeed register. 221 * 222 * Some baudrates are not supported by the chip, so we use the next 223 * lower rate supported and update termios c_flag. 224 * 225 * If highspeed register is set to 3, we need to specify sample count 226 * and sample point to increase accuracy. If not, we reset the 227 * registers to their default values. 228 */ 229 baud = uart_get_baud_rate(port, termios, old, 230 port->uartclk / 16 / UART_DIV_MAX, 231 port->uartclk); 232 233 if (baud <= 115200) { 234 serial_port_out(port, UART_MTK_HIGHS, 0x0); 235 quot = uart_get_divisor(port, baud); 236 } else if (baud <= 576000) { 237 serial_port_out(port, UART_MTK_HIGHS, 0x2); 238 239 /* Set to next lower baudrate supported */ 240 if ((baud == 500000) || (baud == 576000)) 241 baud = 460800; 242 quot = DIV_ROUND_UP(port->uartclk, 4 * baud); 243 } else { 244 serial_port_out(port, UART_MTK_HIGHS, 0x3); 245 quot = DIV_ROUND_UP(port->uartclk, 256 * baud); 246 } 247 248 /* 249 * Ok, we're now changing the port state. Do it with 250 * interrupts disabled. 251 */ 252 spin_lock_irqsave(&port->lock, flags); 253 254 /* set DLAB we have cval saved in up->lcr from the call to the core */ 255 serial_port_out(port, UART_LCR, up->lcr | UART_LCR_DLAB); 256 serial_dl_write(up, quot); 257 258 /* reset DLAB */ 259 serial_port_out(port, UART_LCR, up->lcr); 260 261 if (baud > 460800) { 262 unsigned int tmp; 263 264 tmp = DIV_ROUND_CLOSEST(port->uartclk, quot * baud); 265 serial_port_out(port, UART_MTK_SAMPLE_COUNT, tmp - 1); 266 serial_port_out(port, UART_MTK_SAMPLE_POINT, 267 (tmp - 2) >> 1); 268 } else { 269 serial_port_out(port, UART_MTK_SAMPLE_COUNT, 0x00); 270 serial_port_out(port, UART_MTK_SAMPLE_POINT, 0xff); 271 } 272 273 spin_unlock_irqrestore(&port->lock, flags); 274 /* Don't rewrite B0 */ 275 if (tty_termios_baud_rate(termios)) 276 tty_termios_encode_baud_rate(termios, baud, baud); 277 } 278 279 static int __maybe_unused mtk8250_runtime_suspend(struct device *dev) 280 { 281 struct mtk8250_data *data = dev_get_drvdata(dev); 282 283 clk_disable_unprepare(data->uart_clk); 284 clk_disable_unprepare(data->bus_clk); 285 286 return 0; 287 } 288 289 static int __maybe_unused mtk8250_runtime_resume(struct device *dev) 290 { 291 struct mtk8250_data *data = dev_get_drvdata(dev); 292 int err; 293 294 err = clk_prepare_enable(data->uart_clk); 295 if (err) { 296 dev_warn(dev, "Can't enable clock\n"); 297 return err; 298 } 299 300 err = clk_prepare_enable(data->bus_clk); 301 if (err) { 302 dev_warn(dev, "Can't enable bus clock\n"); 303 return err; 304 } 305 306 return 0; 307 } 308 309 static void 310 mtk8250_do_pm(struct uart_port *port, unsigned int state, unsigned int old) 311 { 312 if (!state) 313 pm_runtime_get_sync(port->dev); 314 315 serial8250_do_pm(port, state, old); 316 317 if (state) 318 pm_runtime_put_sync_suspend(port->dev); 319 } 320 321 #ifdef CONFIG_SERIAL_8250_DMA 322 static bool mtk8250_dma_filter(struct dma_chan *chan, void *param) 323 { 324 return false; 325 } 326 #endif 327 328 static int mtk8250_probe_of(struct platform_device *pdev, struct uart_port *p, 329 struct mtk8250_data *data) 330 { 331 #ifdef CONFIG_SERIAL_8250_DMA 332 int dmacnt; 333 #endif 334 335 data->uart_clk = devm_clk_get(&pdev->dev, "baud"); 336 if (IS_ERR(data->uart_clk)) { 337 /* 338 * For compatibility with older device trees try unnamed 339 * clk when no baud clk can be found. 340 */ 341 data->uart_clk = devm_clk_get(&pdev->dev, NULL); 342 if (IS_ERR(data->uart_clk)) { 343 dev_warn(&pdev->dev, "Can't get uart clock\n"); 344 return PTR_ERR(data->uart_clk); 345 } 346 347 return 0; 348 } 349 350 data->bus_clk = devm_clk_get(&pdev->dev, "bus"); 351 if (IS_ERR(data->bus_clk)) 352 return PTR_ERR(data->bus_clk); 353 354 data->dma = NULL; 355 #ifdef CONFIG_SERIAL_8250_DMA 356 dmacnt = of_property_count_strings(pdev->dev.of_node, "dma-names"); 357 if (dmacnt == 2) { 358 data->dma = devm_kzalloc(&pdev->dev, sizeof(*data->dma), 359 GFP_KERNEL); 360 data->dma->fn = mtk8250_dma_filter; 361 data->dma->rx_size = MTK_UART_RX_SIZE; 362 data->dma->rxconf.src_maxburst = MTK_UART_RX_TRIGGER; 363 data->dma->txconf.dst_maxburst = MTK_UART_TX_TRIGGER; 364 } 365 #endif 366 367 return 0; 368 } 369 370 static int mtk8250_probe(struct platform_device *pdev) 371 { 372 struct uart_8250_port uart = {}; 373 struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0); 374 struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0); 375 struct mtk8250_data *data; 376 int err; 377 378 if (!regs || !irq) { 379 dev_err(&pdev->dev, "no registers/irq defined\n"); 380 return -EINVAL; 381 } 382 383 uart.port.membase = devm_ioremap(&pdev->dev, regs->start, 384 resource_size(regs)); 385 if (!uart.port.membase) 386 return -ENOMEM; 387 388 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); 389 if (!data) 390 return -ENOMEM; 391 392 if (pdev->dev.of_node) { 393 err = mtk8250_probe_of(pdev, &uart.port, data); 394 if (err) 395 return err; 396 } else 397 return -ENODEV; 398 399 spin_lock_init(&uart.port.lock); 400 uart.port.mapbase = regs->start; 401 uart.port.irq = irq->start; 402 uart.port.pm = mtk8250_do_pm; 403 uart.port.type = PORT_16550; 404 uart.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT; 405 uart.port.dev = &pdev->dev; 406 uart.port.iotype = UPIO_MEM32; 407 uart.port.regshift = 2; 408 uart.port.private_data = data; 409 uart.port.shutdown = mtk8250_shutdown; 410 uart.port.startup = mtk8250_startup; 411 uart.port.set_termios = mtk8250_set_termios; 412 uart.port.uartclk = clk_get_rate(data->uart_clk); 413 #ifdef CONFIG_SERIAL_8250_DMA 414 if (data->dma) 415 uart.dma = data->dma; 416 #endif 417 418 /* Disable Rate Fix function */ 419 writel(0x0, uart.port.membase + 420 (MTK_UART_RATE_FIX << uart.port.regshift)); 421 422 platform_set_drvdata(pdev, data); 423 424 err = mtk8250_runtime_resume(&pdev->dev); 425 if (err) 426 return err; 427 428 data->line = serial8250_register_8250_port(&uart); 429 if (data->line < 0) 430 return data->line; 431 432 pm_runtime_set_active(&pdev->dev); 433 pm_runtime_enable(&pdev->dev); 434 435 return 0; 436 } 437 438 static int mtk8250_remove(struct platform_device *pdev) 439 { 440 struct mtk8250_data *data = platform_get_drvdata(pdev); 441 442 pm_runtime_get_sync(&pdev->dev); 443 444 serial8250_unregister_port(data->line); 445 mtk8250_runtime_suspend(&pdev->dev); 446 447 pm_runtime_disable(&pdev->dev); 448 pm_runtime_put_noidle(&pdev->dev); 449 450 return 0; 451 } 452 453 static int __maybe_unused mtk8250_suspend(struct device *dev) 454 { 455 struct mtk8250_data *data = dev_get_drvdata(dev); 456 457 serial8250_suspend_port(data->line); 458 459 return 0; 460 } 461 462 static int __maybe_unused mtk8250_resume(struct device *dev) 463 { 464 struct mtk8250_data *data = dev_get_drvdata(dev); 465 466 serial8250_resume_port(data->line); 467 468 return 0; 469 } 470 471 static const struct dev_pm_ops mtk8250_pm_ops = { 472 SET_SYSTEM_SLEEP_PM_OPS(mtk8250_suspend, mtk8250_resume) 473 SET_RUNTIME_PM_OPS(mtk8250_runtime_suspend, mtk8250_runtime_resume, 474 NULL) 475 }; 476 477 static const struct of_device_id mtk8250_of_match[] = { 478 { .compatible = "mediatek,mt6577-uart" }, 479 { /* Sentinel */ } 480 }; 481 MODULE_DEVICE_TABLE(of, mtk8250_of_match); 482 483 static struct platform_driver mtk8250_platform_driver = { 484 .driver = { 485 .name = "mt6577-uart", 486 .pm = &mtk8250_pm_ops, 487 .of_match_table = mtk8250_of_match, 488 }, 489 .probe = mtk8250_probe, 490 .remove = mtk8250_remove, 491 }; 492 module_platform_driver(mtk8250_platform_driver); 493 494 #ifdef CONFIG_SERIAL_8250_CONSOLE 495 static int __init early_mtk8250_setup(struct earlycon_device *device, 496 const char *options) 497 { 498 if (!device->port.membase) 499 return -ENODEV; 500 501 device->port.iotype = UPIO_MEM32; 502 503 return early_serial8250_setup(device, NULL); 504 } 505 506 OF_EARLYCON_DECLARE(mtk8250, "mediatek,mt6577-uart", early_mtk8250_setup); 507 #endif 508 509 MODULE_AUTHOR("Matthias Brugger"); 510 MODULE_LICENSE("GPL"); 511 MODULE_DESCRIPTION("Mediatek 8250 serial port driver"); 512