1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Serial Port driver for Aspeed VUART device 4 * 5 * Copyright (C) 2016 Jeremy Kerr <jk@ozlabs.org>, IBM Corp. 6 * Copyright (C) 2006 Arnd Bergmann <arnd@arndb.de>, IBM Corp. 7 */ 8 #include <linux/device.h> 9 #include <linux/module.h> 10 #include <linux/of_address.h> 11 #include <linux/of_irq.h> 12 #include <linux/of_platform.h> 13 #include <linux/regmap.h> 14 #include <linux/mfd/syscon.h> 15 #include <linux/tty.h> 16 #include <linux/tty_flip.h> 17 #include <linux/clk.h> 18 19 #include "8250.h" 20 21 #define ASPEED_VUART_GCRA 0x20 22 #define ASPEED_VUART_GCRA_VUART_EN BIT(0) 23 #define ASPEED_VUART_GCRA_HOST_SIRQ_POLARITY BIT(1) 24 #define ASPEED_VUART_GCRA_DISABLE_HOST_TX_DISCARD BIT(5) 25 #define ASPEED_VUART_GCRB 0x24 26 #define ASPEED_VUART_GCRB_HOST_SIRQ_MASK GENMASK(7, 4) 27 #define ASPEED_VUART_GCRB_HOST_SIRQ_SHIFT 4 28 #define ASPEED_VUART_ADDRL 0x28 29 #define ASPEED_VUART_ADDRH 0x2c 30 31 #define ASPEED_VUART_DEFAULT_LPC_ADDR 0x3f8 32 #define ASPEED_VUART_DEFAULT_SIRQ 4 33 #define ASPEED_VUART_DEFAULT_SIRQ_POLARITY IRQ_TYPE_LEVEL_LOW 34 35 struct aspeed_vuart { 36 struct device *dev; 37 struct clk *clk; 38 int line; 39 struct timer_list unthrottle_timer; 40 struct uart_8250_port *port; 41 }; 42 43 /* 44 * If we fill the tty flip buffers, we throttle the data ready interrupt 45 * to prevent dropped characters. This timeout defines how long we wait 46 * to (conditionally, depending on buffer state) unthrottle. 47 */ 48 static const int unthrottle_timeout = HZ/10; 49 50 /* 51 * The VUART is basically two UART 'front ends' connected by their FIFO 52 * (no actual serial line in between). One is on the BMC side (management 53 * controller) and one is on the host CPU side. 54 * 55 * It allows the BMC to provide to the host a "UART" that pipes into 56 * the BMC itself and can then be turned by the BMC into a network console 57 * of some sort for example. 58 * 59 * This driver is for the BMC side. The sysfs files allow the BMC 60 * userspace which owns the system configuration policy, to specify 61 * at what IO port and interrupt number the host side will appear 62 * to the host on the Host <-> BMC LPC bus. It could be different on a 63 * different system (though most of them use 3f8/4). 64 */ 65 66 static inline u8 aspeed_vuart_readb(struct aspeed_vuart *vuart, u8 reg) 67 { 68 return readb(vuart->port->port.membase + reg); 69 } 70 71 static inline void aspeed_vuart_writeb(struct aspeed_vuart *vuart, u8 val, u8 reg) 72 { 73 writeb(val, vuart->port->port.membase + reg); 74 } 75 76 static ssize_t lpc_address_show(struct device *dev, 77 struct device_attribute *attr, char *buf) 78 { 79 struct aspeed_vuart *vuart = dev_get_drvdata(dev); 80 u16 addr; 81 82 addr = (aspeed_vuart_readb(vuart, ASPEED_VUART_ADDRH) << 8) | 83 (aspeed_vuart_readb(vuart, ASPEED_VUART_ADDRL)); 84 85 return sysfs_emit(buf, "0x%x\n", addr); 86 } 87 88 static int aspeed_vuart_set_lpc_address(struct aspeed_vuart *vuart, u32 addr) 89 { 90 if (addr > U16_MAX) 91 return -EINVAL; 92 93 aspeed_vuart_writeb(vuart, addr >> 8, ASPEED_VUART_ADDRH); 94 aspeed_vuart_writeb(vuart, addr >> 0, ASPEED_VUART_ADDRL); 95 96 return 0; 97 } 98 99 static ssize_t lpc_address_store(struct device *dev, 100 struct device_attribute *attr, 101 const char *buf, size_t count) 102 { 103 struct aspeed_vuart *vuart = dev_get_drvdata(dev); 104 u32 val; 105 int err; 106 107 err = kstrtou32(buf, 0, &val); 108 if (err) 109 return err; 110 111 err = aspeed_vuart_set_lpc_address(vuart, val); 112 return err ? : count; 113 } 114 115 static DEVICE_ATTR_RW(lpc_address); 116 117 static ssize_t sirq_show(struct device *dev, 118 struct device_attribute *attr, char *buf) 119 { 120 struct aspeed_vuart *vuart = dev_get_drvdata(dev); 121 u8 reg; 122 123 reg = aspeed_vuart_readb(vuart, ASPEED_VUART_GCRB); 124 reg &= ASPEED_VUART_GCRB_HOST_SIRQ_MASK; 125 reg >>= ASPEED_VUART_GCRB_HOST_SIRQ_SHIFT; 126 127 return sysfs_emit(buf, "%u\n", reg); 128 } 129 130 static int aspeed_vuart_set_sirq(struct aspeed_vuart *vuart, u32 sirq) 131 { 132 u8 reg; 133 134 if (sirq > (ASPEED_VUART_GCRB_HOST_SIRQ_MASK >> ASPEED_VUART_GCRB_HOST_SIRQ_SHIFT)) 135 return -EINVAL; 136 137 sirq <<= ASPEED_VUART_GCRB_HOST_SIRQ_SHIFT; 138 sirq &= ASPEED_VUART_GCRB_HOST_SIRQ_MASK; 139 140 reg = aspeed_vuart_readb(vuart, ASPEED_VUART_GCRB); 141 reg &= ~ASPEED_VUART_GCRB_HOST_SIRQ_MASK; 142 reg |= sirq; 143 aspeed_vuart_writeb(vuart, reg, ASPEED_VUART_GCRB); 144 145 return 0; 146 } 147 148 static ssize_t sirq_store(struct device *dev, struct device_attribute *attr, 149 const char *buf, size_t count) 150 { 151 struct aspeed_vuart *vuart = dev_get_drvdata(dev); 152 unsigned long val; 153 int err; 154 155 err = kstrtoul(buf, 0, &val); 156 if (err) 157 return err; 158 159 err = aspeed_vuart_set_sirq(vuart, val); 160 return err ? : count; 161 } 162 163 static DEVICE_ATTR_RW(sirq); 164 165 static ssize_t sirq_polarity_show(struct device *dev, 166 struct device_attribute *attr, char *buf) 167 { 168 struct aspeed_vuart *vuart = dev_get_drvdata(dev); 169 u8 reg; 170 171 reg = aspeed_vuart_readb(vuart, ASPEED_VUART_GCRA); 172 reg &= ASPEED_VUART_GCRA_HOST_SIRQ_POLARITY; 173 174 return sysfs_emit(buf, "%u\n", reg ? 1 : 0); 175 } 176 177 static void aspeed_vuart_set_sirq_polarity(struct aspeed_vuart *vuart, 178 bool polarity) 179 { 180 u8 reg = aspeed_vuart_readb(vuart, ASPEED_VUART_GCRA); 181 182 if (polarity) 183 reg |= ASPEED_VUART_GCRA_HOST_SIRQ_POLARITY; 184 else 185 reg &= ~ASPEED_VUART_GCRA_HOST_SIRQ_POLARITY; 186 187 aspeed_vuart_writeb(vuart, reg, ASPEED_VUART_GCRA); 188 } 189 190 static ssize_t sirq_polarity_store(struct device *dev, 191 struct device_attribute *attr, 192 const char *buf, size_t count) 193 { 194 struct aspeed_vuart *vuart = dev_get_drvdata(dev); 195 unsigned long val; 196 int err; 197 198 err = kstrtoul(buf, 0, &val); 199 if (err) 200 return err; 201 202 aspeed_vuart_set_sirq_polarity(vuart, val != 0); 203 204 return count; 205 } 206 207 static DEVICE_ATTR_RW(sirq_polarity); 208 209 static struct attribute *aspeed_vuart_attrs[] = { 210 &dev_attr_sirq.attr, 211 &dev_attr_sirq_polarity.attr, 212 &dev_attr_lpc_address.attr, 213 NULL, 214 }; 215 216 static const struct attribute_group aspeed_vuart_attr_group = { 217 .attrs = aspeed_vuart_attrs, 218 }; 219 220 static void aspeed_vuart_set_enabled(struct aspeed_vuart *vuart, bool enabled) 221 { 222 u8 reg = aspeed_vuart_readb(vuart, ASPEED_VUART_GCRA); 223 224 if (enabled) 225 reg |= ASPEED_VUART_GCRA_VUART_EN; 226 else 227 reg &= ~ASPEED_VUART_GCRA_VUART_EN; 228 229 aspeed_vuart_writeb(vuart, reg, ASPEED_VUART_GCRA); 230 } 231 232 static void aspeed_vuart_set_host_tx_discard(struct aspeed_vuart *vuart, 233 bool discard) 234 { 235 u8 reg; 236 237 reg = aspeed_vuart_readb(vuart, ASPEED_VUART_GCRA); 238 239 /* If the DISABLE_HOST_TX_DISCARD bit is set, discard is disabled */ 240 if (!discard) 241 reg |= ASPEED_VUART_GCRA_DISABLE_HOST_TX_DISCARD; 242 else 243 reg &= ~ASPEED_VUART_GCRA_DISABLE_HOST_TX_DISCARD; 244 245 aspeed_vuart_writeb(vuart, reg, ASPEED_VUART_GCRA); 246 } 247 248 static int aspeed_vuart_startup(struct uart_port *uart_port) 249 { 250 struct uart_8250_port *uart_8250_port = up_to_u8250p(uart_port); 251 struct aspeed_vuart *vuart = uart_8250_port->port.private_data; 252 int rc; 253 254 rc = serial8250_do_startup(uart_port); 255 if (rc) 256 return rc; 257 258 aspeed_vuart_set_host_tx_discard(vuart, false); 259 260 return 0; 261 } 262 263 static void aspeed_vuart_shutdown(struct uart_port *uart_port) 264 { 265 struct uart_8250_port *uart_8250_port = up_to_u8250p(uart_port); 266 struct aspeed_vuart *vuart = uart_8250_port->port.private_data; 267 268 aspeed_vuart_set_host_tx_discard(vuart, true); 269 270 serial8250_do_shutdown(uart_port); 271 } 272 273 static void __aspeed_vuart_set_throttle(struct uart_8250_port *up, 274 bool throttle) 275 { 276 unsigned char irqs = UART_IER_RLSI | UART_IER_RDI; 277 278 /* Port locked to synchronize UART_IER access against the console. */ 279 lockdep_assert_held_once(&up->port.lock); 280 281 up->ier &= ~irqs; 282 if (!throttle) 283 up->ier |= irqs; 284 serial_out(up, UART_IER, up->ier); 285 } 286 static void aspeed_vuart_set_throttle(struct uart_port *port, bool throttle) 287 { 288 struct uart_8250_port *up = up_to_u8250p(port); 289 unsigned long flags; 290 291 spin_lock_irqsave(&port->lock, flags); 292 __aspeed_vuart_set_throttle(up, throttle); 293 spin_unlock_irqrestore(&port->lock, flags); 294 } 295 296 static void aspeed_vuart_throttle(struct uart_port *port) 297 { 298 aspeed_vuart_set_throttle(port, true); 299 } 300 301 static void aspeed_vuart_unthrottle(struct uart_port *port) 302 { 303 aspeed_vuart_set_throttle(port, false); 304 } 305 306 static void aspeed_vuart_unthrottle_exp(struct timer_list *timer) 307 { 308 struct aspeed_vuart *vuart = from_timer(vuart, timer, unthrottle_timer); 309 struct uart_8250_port *up = vuart->port; 310 311 if (!tty_buffer_space_avail(&up->port.state->port)) { 312 mod_timer(&vuart->unthrottle_timer, 313 jiffies + unthrottle_timeout); 314 return; 315 } 316 317 aspeed_vuart_unthrottle(&up->port); 318 } 319 320 /* 321 * Custom interrupt handler to manage finer-grained flow control. Although we 322 * have throttle/unthrottle callbacks, we've seen that the VUART device can 323 * deliver characters faster than the ldisc has a chance to check buffer space 324 * against the throttle threshold. This results in dropped characters before 325 * the throttle. 326 * 327 * We do this by checking for flip buffer space before RX. If we have no space, 328 * throttle now and schedule an unthrottle for later, once the ldisc has had 329 * a chance to drain the buffers. 330 */ 331 static int aspeed_vuart_handle_irq(struct uart_port *port) 332 { 333 struct uart_8250_port *up = up_to_u8250p(port); 334 unsigned int iir, lsr; 335 unsigned long flags; 336 unsigned int space, count; 337 338 iir = serial_port_in(port, UART_IIR); 339 340 if (iir & UART_IIR_NO_INT) 341 return 0; 342 343 spin_lock_irqsave(&port->lock, flags); 344 345 lsr = serial_port_in(port, UART_LSR); 346 347 if (lsr & (UART_LSR_DR | UART_LSR_BI)) { 348 space = tty_buffer_space_avail(&port->state->port); 349 350 if (!space) { 351 /* throttle and schedule an unthrottle later */ 352 struct aspeed_vuart *vuart = port->private_data; 353 __aspeed_vuart_set_throttle(up, true); 354 355 if (!timer_pending(&vuart->unthrottle_timer)) 356 mod_timer(&vuart->unthrottle_timer, 357 jiffies + unthrottle_timeout); 358 359 } else { 360 count = min(space, 256U); 361 362 do { 363 serial8250_read_char(up, lsr); 364 lsr = serial_in(up, UART_LSR); 365 if (--count == 0) 366 break; 367 } while (lsr & (UART_LSR_DR | UART_LSR_BI)); 368 369 tty_flip_buffer_push(&port->state->port); 370 } 371 } 372 373 serial8250_modem_status(up); 374 if (lsr & UART_LSR_THRE) 375 serial8250_tx_chars(up); 376 377 uart_unlock_and_check_sysrq_irqrestore(port, flags); 378 379 return 1; 380 } 381 382 static void aspeed_vuart_auto_configure_sirq_polarity( 383 struct aspeed_vuart *vuart, struct device_node *syscon_np, 384 u32 reg_offset, u32 reg_mask) 385 { 386 struct regmap *regmap; 387 u32 value; 388 389 regmap = syscon_node_to_regmap(syscon_np); 390 if (IS_ERR(regmap)) { 391 dev_warn(vuart->dev, 392 "could not get regmap for aspeed,sirq-polarity-sense\n"); 393 return; 394 } 395 if (regmap_read(regmap, reg_offset, &value)) { 396 dev_warn(vuart->dev, "could not read hw strap table\n"); 397 return; 398 } 399 400 aspeed_vuart_set_sirq_polarity(vuart, (value & reg_mask) == 0); 401 } 402 403 static int aspeed_vuart_map_irq_polarity(u32 dt) 404 { 405 switch (dt) { 406 case IRQ_TYPE_LEVEL_LOW: 407 return 0; 408 case IRQ_TYPE_LEVEL_HIGH: 409 return 1; 410 default: 411 return -EINVAL; 412 } 413 } 414 415 static int aspeed_vuart_probe(struct platform_device *pdev) 416 { 417 struct of_phandle_args sirq_polarity_sense_args; 418 struct uart_8250_port port; 419 struct aspeed_vuart *vuart; 420 struct device_node *np; 421 struct resource *res; 422 u32 clk, prop, sirq[2]; 423 int rc, sirq_polarity; 424 425 np = pdev->dev.of_node; 426 427 vuart = devm_kzalloc(&pdev->dev, sizeof(*vuart), GFP_KERNEL); 428 if (!vuart) 429 return -ENOMEM; 430 431 vuart->dev = &pdev->dev; 432 timer_setup(&vuart->unthrottle_timer, aspeed_vuart_unthrottle_exp, 0); 433 434 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 435 if (!res) 436 return -EINVAL; 437 438 memset(&port, 0, sizeof(port)); 439 port.port.private_data = vuart; 440 port.port.mapbase = res->start; 441 port.port.mapsize = resource_size(res); 442 port.port.startup = aspeed_vuart_startup; 443 port.port.shutdown = aspeed_vuart_shutdown; 444 port.port.throttle = aspeed_vuart_throttle; 445 port.port.unthrottle = aspeed_vuart_unthrottle; 446 port.port.status = UPSTAT_SYNC_FIFO; 447 port.port.dev = &pdev->dev; 448 port.port.has_sysrq = IS_ENABLED(CONFIG_SERIAL_8250_CONSOLE); 449 port.bugs |= UART_BUG_TXRACE; 450 451 rc = sysfs_create_group(&vuart->dev->kobj, &aspeed_vuart_attr_group); 452 if (rc < 0) 453 return rc; 454 455 if (of_property_read_u32(np, "clock-frequency", &clk)) { 456 vuart->clk = devm_clk_get(&pdev->dev, NULL); 457 if (IS_ERR(vuart->clk)) { 458 dev_warn(&pdev->dev, 459 "clk or clock-frequency not defined\n"); 460 rc = PTR_ERR(vuart->clk); 461 goto err_sysfs_remove; 462 } 463 464 rc = clk_prepare_enable(vuart->clk); 465 if (rc < 0) 466 goto err_sysfs_remove; 467 468 clk = clk_get_rate(vuart->clk); 469 } 470 471 /* If current-speed was set, then try not to change it. */ 472 if (of_property_read_u32(np, "current-speed", &prop) == 0) 473 port.port.custom_divisor = clk / (16 * prop); 474 475 /* Check for shifted address mapping */ 476 if (of_property_read_u32(np, "reg-offset", &prop) == 0) 477 port.port.mapbase += prop; 478 479 /* Check for registers offset within the devices address range */ 480 if (of_property_read_u32(np, "reg-shift", &prop) == 0) 481 port.port.regshift = prop; 482 483 /* Check for fifo size */ 484 if (of_property_read_u32(np, "fifo-size", &prop) == 0) 485 port.port.fifosize = prop; 486 487 /* Check for a fixed line number */ 488 rc = of_alias_get_id(np, "serial"); 489 if (rc >= 0) 490 port.port.line = rc; 491 492 port.port.irq = irq_of_parse_and_map(np, 0); 493 port.port.handle_irq = aspeed_vuart_handle_irq; 494 port.port.iotype = UPIO_MEM; 495 port.port.type = PORT_ASPEED_VUART; 496 port.port.uartclk = clk; 497 port.port.flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_IOREMAP 498 | UPF_FIXED_PORT | UPF_FIXED_TYPE | UPF_NO_THRE_TEST; 499 500 if (of_property_read_bool(np, "no-loopback-test")) 501 port.port.flags |= UPF_SKIP_TEST; 502 503 if (port.port.fifosize) 504 port.capabilities = UART_CAP_FIFO; 505 506 if (of_property_read_bool(np, "auto-flow-control")) 507 port.capabilities |= UART_CAP_AFE; 508 509 rc = serial8250_register_8250_port(&port); 510 if (rc < 0) 511 goto err_clk_disable; 512 513 vuart->line = rc; 514 vuart->port = serial8250_get_port(vuart->line); 515 516 rc = of_parse_phandle_with_fixed_args( 517 np, "aspeed,sirq-polarity-sense", 2, 0, 518 &sirq_polarity_sense_args); 519 if (rc < 0) { 520 dev_dbg(&pdev->dev, 521 "aspeed,sirq-polarity-sense property not found\n"); 522 } else { 523 aspeed_vuart_auto_configure_sirq_polarity( 524 vuart, sirq_polarity_sense_args.np, 525 sirq_polarity_sense_args.args[0], 526 BIT(sirq_polarity_sense_args.args[1])); 527 of_node_put(sirq_polarity_sense_args.np); 528 } 529 530 rc = of_property_read_u32(np, "aspeed,lpc-io-reg", &prop); 531 if (rc < 0) 532 prop = ASPEED_VUART_DEFAULT_LPC_ADDR; 533 534 rc = aspeed_vuart_set_lpc_address(vuart, prop); 535 if (rc < 0) { 536 dev_err(&pdev->dev, "invalid value in aspeed,lpc-io-reg property\n"); 537 goto err_clk_disable; 538 } 539 540 rc = of_property_read_u32_array(np, "aspeed,lpc-interrupts", sirq, 2); 541 if (rc < 0) { 542 sirq[0] = ASPEED_VUART_DEFAULT_SIRQ; 543 sirq[1] = ASPEED_VUART_DEFAULT_SIRQ_POLARITY; 544 } 545 546 rc = aspeed_vuart_set_sirq(vuart, sirq[0]); 547 if (rc < 0) { 548 dev_err(&pdev->dev, "invalid sirq number in aspeed,lpc-interrupts property\n"); 549 goto err_clk_disable; 550 } 551 552 sirq_polarity = aspeed_vuart_map_irq_polarity(sirq[1]); 553 if (sirq_polarity < 0) { 554 dev_err(&pdev->dev, "invalid sirq polarity in aspeed,lpc-interrupts property\n"); 555 rc = sirq_polarity; 556 goto err_clk_disable; 557 } 558 559 aspeed_vuart_set_sirq_polarity(vuart, sirq_polarity); 560 561 aspeed_vuart_set_enabled(vuart, true); 562 aspeed_vuart_set_host_tx_discard(vuart, true); 563 platform_set_drvdata(pdev, vuart); 564 565 return 0; 566 567 err_clk_disable: 568 clk_disable_unprepare(vuart->clk); 569 irq_dispose_mapping(port.port.irq); 570 err_sysfs_remove: 571 sysfs_remove_group(&vuart->dev->kobj, &aspeed_vuart_attr_group); 572 return rc; 573 } 574 575 static int aspeed_vuart_remove(struct platform_device *pdev) 576 { 577 struct aspeed_vuart *vuart = platform_get_drvdata(pdev); 578 579 del_timer_sync(&vuart->unthrottle_timer); 580 aspeed_vuart_set_enabled(vuart, false); 581 serial8250_unregister_port(vuart->line); 582 sysfs_remove_group(&vuart->dev->kobj, &aspeed_vuart_attr_group); 583 clk_disable_unprepare(vuart->clk); 584 585 return 0; 586 } 587 588 static const struct of_device_id aspeed_vuart_table[] = { 589 { .compatible = "aspeed,ast2400-vuart" }, 590 { .compatible = "aspeed,ast2500-vuart" }, 591 { }, 592 }; 593 594 static struct platform_driver aspeed_vuart_driver = { 595 .driver = { 596 .name = "aspeed-vuart", 597 .of_match_table = aspeed_vuart_table, 598 }, 599 .probe = aspeed_vuart_probe, 600 .remove = aspeed_vuart_remove, 601 }; 602 603 module_platform_driver(aspeed_vuart_driver); 604 605 MODULE_AUTHOR("Jeremy Kerr <jk@ozlabs.org>"); 606 MODULE_LICENSE("GPL"); 607 MODULE_DESCRIPTION("Driver for Aspeed VUART device"); 608