drivers/tty/goldfish.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2007 Google, Inc.
   4  * Copyright (C) 2012 Intel, Inc.
   5  * Copyright (C) 2017 Imagination Technologies Ltd.
   6  */
   7
   8 #include <linux/console.h>
   9 #include <linux/interrupt.h>
  10 #include <linux/platform_device.h>
  11 #include <linux/tty.h>
  12 #include <linux/tty_flip.h>
  13 #include <linux/slab.h>
  14 #include <linux/io.h>
  15 #include <linux/module.h>
  16 #include <linux/goldfish.h>
  17 #include <linux/mm.h>
  18 #include <linux/dma-mapping.h>
  19 #include <linux/serial_core.h>
  20
  21 /* Goldfish tty register's offsets */
  22 #define GOLDFISH_TTY_REG_BYTES_READY    0x04
  23 #define GOLDFISH_TTY_REG_CMD            0x08
  24 #define GOLDFISH_TTY_REG_DATA_PTR       0x10
  25 #define GOLDFISH_TTY_REG_DATA_LEN       0x14
  26 #define GOLDFISH_TTY_REG_DATA_PTR_HIGH  0x18
  27 #define GOLDFISH_TTY_REG_VERSION        0x20
  28
  29 /* Goldfish tty commands */
  30 #define GOLDFISH_TTY_CMD_INT_DISABLE    0
  31 #define GOLDFISH_TTY_CMD_INT_ENABLE     1
  32 #define GOLDFISH_TTY_CMD_WRITE_BUFFER   2
  33 #define GOLDFISH_TTY_CMD_READ_BUFFER    3
  34
  35 struct goldfish_tty {
  36         struct tty_port port;
  37         spinlock_t lock;
  38         void __iomem *base;
  39         u32 irq;
  40         int opencount;
  41         struct console console;
  42         u32 version;
  43         struct device *dev;
  44 };
  45
  46 static DEFINE_MUTEX(goldfish_tty_lock);
  47 static struct tty_driver *goldfish_tty_driver;
  48 static u32 goldfish_tty_line_count = 8;
  49 static u32 goldfish_tty_current_line_count;
  50 static struct goldfish_tty *goldfish_ttys;
  51
  52 static void do_rw_io(struct goldfish_tty *qtty,
  53                      unsigned long address,
  54                      unsigned int count,
  55                      int is_write)
  56 {
  57         unsigned long irq_flags;
  58         void __iomem *base = qtty->base;
  59
  60         spin_lock_irqsave(&qtty->lock, irq_flags);
  61         gf_write_ptr((void *)address, base + GOLDFISH_TTY_REG_DATA_PTR,
  62                      base + GOLDFISH_TTY_REG_DATA_PTR_HIGH);
  63         writel(count, base + GOLDFISH_TTY_REG_DATA_LEN);
  64
  65         if (is_write)
  66                 writel(GOLDFISH_TTY_CMD_WRITE_BUFFER,
  67                        base + GOLDFISH_TTY_REG_CMD);
  68         else
  69                 writel(GOLDFISH_TTY_CMD_READ_BUFFER,
  70                        base + GOLDFISH_TTY_REG_CMD);
  71
  72         spin_unlock_irqrestore(&qtty->lock, irq_flags);
  73 }
  74
  75 static void goldfish_tty_rw(struct goldfish_tty *qtty,
  76                             unsigned long addr,
  77                             unsigned int count,
  78                             int is_write)
  79 {
  80         dma_addr_t dma_handle;
  81         enum dma_data_direction dma_dir;
  82
  83         dma_dir = (is_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
  84         if (qtty->version > 0) {
  85                 /*
  86                  * Goldfish TTY for Ranchu platform uses
  87                  * physical addresses and DMA for read/write operations
  88                  */
  89                 unsigned long addr_end = addr + count;
  90
  91                 while (addr < addr_end) {
  92                         unsigned long pg_end = (addr & PAGE_MASK) + PAGE_SIZE;
  93                         unsigned long next =
  94                                         pg_end < addr_end ? pg_end : addr_end;
  95                         unsigned long avail = next - addr;
  96
  97                         /*
  98                          * Map the buffer's virtual address to the DMA address
  99                          * so the buffer can be accessed by the device.
 100                          */
 101                         dma_handle = dma_map_single(qtty->dev, (void *)addr,
 102                                                     avail, dma_dir);
 103
 104                         if (dma_mapping_error(qtty->dev, dma_handle)) {
 105                                 dev_err(qtty->dev, "tty: DMA mapping error.\n");
 106                                 return;
 107                         }
 108                         do_rw_io(qtty, dma_handle, avail, is_write);
 109
 110                         /*
 111                          * Unmap the previously mapped region after
 112                          * the completion of the read/write operation.
 113                          */
 114                         dma_unmap_single(qtty->dev, dma_handle, avail, dma_dir);
 115
 116                         addr += avail;
 117                 }
 118         } else {
 119                 /*
 120                  * Old style Goldfish TTY used on the Goldfish platform
 121                  * uses virtual addresses.
 122                  */
 123                 do_rw_io(qtty, addr, count, is_write);
 124         }
 125 }
 126
 127 static void goldfish_tty_do_write(int line, const char *buf,
 128                                   unsigned int count)
 129 {
 130         struct goldfish_tty *qtty = &goldfish_ttys[line];
 131         unsigned long address = (unsigned long)(void *)buf;
 132
 133         goldfish_tty_rw(qtty, address, count, 1);
 134 }
 135
 136 static irqreturn_t goldfish_tty_interrupt(int irq, void *dev_id)
 137 {
 138         struct goldfish_tty *qtty = dev_id;
 139         void __iomem *base = qtty->base;
 140         unsigned long address;
 141         unsigned char *buf;
 142         u32 count;
 143
 144         count = readl(base + GOLDFISH_TTY_REG_BYTES_READY);
 145         if (count == 0)
 146                 return IRQ_NONE;
 147
 148         count = tty_prepare_flip_string(&qtty->port, &buf, count);
 149
 150         address = (unsigned long)(void *)buf;
 151         goldfish_tty_rw(qtty, address, count, 0);
 152
 153         tty_schedule_flip(&qtty->port);
 154         return IRQ_HANDLED;
 155 }
 156
 157 static int goldfish_tty_activate(struct tty_port *port, struct tty_struct *tty)
 158 {
 159         struct goldfish_tty *qtty = container_of(port, struct goldfish_tty,
 160                                                                         port);
 161         writel(GOLDFISH_TTY_CMD_INT_ENABLE, qtty->base + GOLDFISH_TTY_REG_CMD);
 162         return 0;
 163 }
 164
 165 static void goldfish_tty_shutdown(struct tty_port *port)
 166 {
 167         struct goldfish_tty *qtty = container_of(port, struct goldfish_tty,
 168                                                                         port);
 169         writel(GOLDFISH_TTY_CMD_INT_DISABLE, qtty->base + GOLDFISH_TTY_REG_CMD);
 170 }
 171
 172 static int goldfish_tty_open(struct tty_struct *tty, struct file *filp)
 173 {
 174         struct goldfish_tty *qtty = &goldfish_ttys[tty->index];
 175         return tty_port_open(&qtty->port, tty, filp);
 176 }
 177
 178 static void goldfish_tty_close(struct tty_struct *tty, struct file *filp)
 179 {
 180         tty_port_close(tty->port, tty, filp);
 181 }
 182
 183 static void goldfish_tty_hangup(struct tty_struct *tty)
 184 {
 185         tty_port_hangup(tty->port);
 186 }
 187
 188 static int goldfish_tty_write(struct tty_struct *tty, const unsigned char *buf,
 189                                                                 int count)
 190 {
 191         goldfish_tty_do_write(tty->index, buf, count);
 192         return count;
 193 }
 194
 195 static int goldfish_tty_write_room(struct tty_struct *tty)
 196 {
 197         return 0x10000;
 198 }
 199
 200 static int goldfish_tty_chars_in_buffer(struct tty_struct *tty)
 201 {
 202         struct goldfish_tty *qtty = &goldfish_ttys[tty->index];
 203         void __iomem *base = qtty->base;
 204         return readl(base + GOLDFISH_TTY_REG_BYTES_READY);
 205 }
 206
 207 static void goldfish_tty_console_write(struct console *co, const char *b,
 208                                                                 unsigned count)
 209 {
 210         goldfish_tty_do_write(co->index, b, count);
 211 }
 212
 213 static struct tty_driver *goldfish_tty_console_device(struct console *c,
 214                                                                 int *index)
 215 {
 216         *index = c->index;
 217         return goldfish_tty_driver;
 218 }
 219
 220 static int goldfish_tty_console_setup(struct console *co, char *options)
 221 {
 222         if ((unsigned)co->index >= goldfish_tty_line_count)
 223                 return -ENODEV;
 224         if (!goldfish_ttys[co->index].base)
 225                 return -ENODEV;
 226         return 0;
 227 }
 228
 229 static const struct tty_port_operations goldfish_port_ops = {
 230         .activate = goldfish_tty_activate,
 231         .shutdown = goldfish_tty_shutdown
 232 };
 233
 234 static const struct tty_operations goldfish_tty_ops = {
 235         .open = goldfish_tty_open,
 236         .close = goldfish_tty_close,
 237         .hangup = goldfish_tty_hangup,
 238         .write = goldfish_tty_write,
 239         .write_room = goldfish_tty_write_room,
 240         .chars_in_buffer = goldfish_tty_chars_in_buffer,
 241 };
 242
 243 static int goldfish_tty_create_driver(void)
 244 {
 245         int ret;
 246         struct tty_driver *tty;
 247
 248         goldfish_ttys = kcalloc(goldfish_tty_line_count,
 249                                 sizeof(*goldfish_ttys),
 250                                 GFP_KERNEL);
 251         if (goldfish_ttys == NULL) {
 252                 ret = -ENOMEM;
 253                 goto err_alloc_goldfish_ttys_failed;
 254         }
 255         tty = alloc_tty_driver(goldfish_tty_line_count);
 256         if (tty == NULL) {
 257                 ret = -ENOMEM;
 258                 goto err_alloc_tty_driver_failed;
 259         }
 260         tty->driver_name = "goldfish";
 261         tty->name = "ttyGF";
 262         tty->type = TTY_DRIVER_TYPE_SERIAL;
 263         tty->subtype = SERIAL_TYPE_NORMAL;
 264         tty->init_termios = tty_std_termios;
 265         tty->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 266                                                 TTY_DRIVER_DYNAMIC_DEV;
 267         tty_set_operations(tty, &goldfish_tty_ops);
 268         ret = tty_register_driver(tty);
 269         if (ret)
 270                 goto err_tty_register_driver_failed;
 271
 272         goldfish_tty_driver = tty;
 273         return 0;
 274
 275 err_tty_register_driver_failed:
 276         put_tty_driver(tty);
 277 err_alloc_tty_driver_failed:
 278         kfree(goldfish_ttys);
 279         goldfish_ttys = NULL;
 280 err_alloc_goldfish_ttys_failed:
 281         return ret;
 282 }
 283
 284 static void goldfish_tty_delete_driver(void)
 285 {
 286         tty_unregister_driver(goldfish_tty_driver);
 287         put_tty_driver(goldfish_tty_driver);
 288         goldfish_tty_driver = NULL;
 289         kfree(goldfish_ttys);
 290         goldfish_ttys = NULL;
 291 }
 292
 293 static int goldfish_tty_probe(struct platform_device *pdev)
 294 {
 295         struct goldfish_tty *qtty;
 296         int ret = -ENODEV;
 297         struct resource *r;
 298         struct device *ttydev;
 299         void __iomem *base;
 300         u32 irq;
 301         unsigned int line;
 302
 303         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 304         if (!r) {
 305                 pr_err("goldfish_tty: No MEM resource available!\n");
 306                 return -ENOMEM;
 307         }
 308
 309         base = ioremap(r->start, 0x1000);
 310         if (!base) {
 311                 pr_err("goldfish_tty: Unable to ioremap base!\n");
 312                 return -ENOMEM;
 313         }
 314
 315         r = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 316         if (!r) {
 317                 pr_err("goldfish_tty: No IRQ resource available!\n");
 318                 goto err_unmap;
 319         }
 320
 321         irq = r->start;
 322
 323         mutex_lock(&goldfish_tty_lock);
 324
 325         if (pdev->id == PLATFORM_DEVID_NONE)
 326                 line = goldfish_tty_current_line_count;
 327         else
 328                 line = pdev->id;
 329
 330         if (line >= goldfish_tty_line_count) {
 331                 pr_err("goldfish_tty: Reached maximum tty number of %d.\n",
 332                        goldfish_tty_current_line_count);
 333                 ret = -ENOMEM;
 334                 goto err_unlock;
 335         }
 336
 337         if (goldfish_tty_current_line_count == 0) {
 338                 ret = goldfish_tty_create_driver();
 339                 if (ret)
 340                         goto err_unlock;
 341         }
 342         goldfish_tty_current_line_count++;
 343
 344         qtty = &goldfish_ttys[line];
 345         spin_lock_init(&qtty->lock);
 346         tty_port_init(&qtty->port);
 347         qtty->port.ops = &goldfish_port_ops;
 348         qtty->base = base;
 349         qtty->irq = irq;
 350         qtty->dev = &pdev->dev;
 351
 352         /*
 353          * Goldfish TTY device used by the Goldfish emulator
 354          * should identify itself with 0, forcing the driver
 355          * to use virtual addresses. Goldfish TTY device
 356          * on Ranchu emulator (qemu2) returns 1 here and
 357          * driver will use physical addresses.
 358          */
 359         qtty->version = readl(base + GOLDFISH_TTY_REG_VERSION);
 360
 361         /*
 362          * Goldfish TTY device on Ranchu emulator (qemu2)
 363          * will use DMA for read/write IO operations.
 364          */
 365         if (qtty->version > 0) {
 366                 /*
 367                  * Initialize dma_mask to 32-bits.
 368                  */
 369                 if (!pdev->dev.dma_mask)
 370                         pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
 371                 ret = dma_set_mask(&pdev->dev, DMA_BIT_MASK(32));
 372                 if (ret) {
 373                         dev_err(&pdev->dev, "No suitable DMA available.\n");
 374                         goto err_dec_line_count;
 375                 }
 376         }
 377
 378         writel(GOLDFISH_TTY_CMD_INT_DISABLE, base + GOLDFISH_TTY_REG_CMD);
 379
 380         ret = request_irq(irq, goldfish_tty_interrupt, IRQF_SHARED,
 381                           "goldfish_tty", qtty);
 382         if (ret) {
 383                 pr_err("goldfish_tty: No IRQ available!\n");
 384                 goto err_dec_line_count;
 385         }
 386
 387         ttydev = tty_port_register_device(&qtty->port, goldfish_tty_driver,
 388                                           line, &pdev->dev);
 389         if (IS_ERR(ttydev)) {
 390                 ret = PTR_ERR(ttydev);
 391                 goto err_tty_register_device_failed;
 392         }
 393
 394         strcpy(qtty->console.name, "ttyGF");
 395         qtty->console.write = goldfish_tty_console_write;
 396         qtty->console.device = goldfish_tty_console_device;
 397         qtty->console.setup = goldfish_tty_console_setup;
 398         qtty->console.flags = CON_PRINTBUFFER;
 399         qtty->console.index = line;
 400         register_console(&qtty->console);
 401         platform_set_drvdata(pdev, qtty);
 402
 403         mutex_unlock(&goldfish_tty_lock);
 404         return 0;
 405
 406 err_tty_register_device_failed:
 407         free_irq(irq, qtty);
 408 err_dec_line_count:
 409         goldfish_tty_current_line_count--;
 410         if (goldfish_tty_current_line_count == 0)
 411                 goldfish_tty_delete_driver();
 412 err_unlock:
 413         mutex_unlock(&goldfish_tty_lock);
 414 err_unmap:
 415         iounmap(base);
 416         return ret;
 417 }
 418
 419 static int goldfish_tty_remove(struct platform_device *pdev)
 420 {
 421         struct goldfish_tty *qtty = platform_get_drvdata(pdev);
 422
 423         mutex_lock(&goldfish_tty_lock);
 424
 425         unregister_console(&qtty->console);
 426         tty_unregister_device(goldfish_tty_driver, qtty->console.index);
 427         iounmap(qtty->base);
 428         qtty->base = NULL;
 429         free_irq(qtty->irq, pdev);
 430         goldfish_tty_current_line_count--;
 431         if (goldfish_tty_current_line_count == 0)
 432                 goldfish_tty_delete_driver();
 433         mutex_unlock(&goldfish_tty_lock);
 434         return 0;
 435 }
 436
 437 #ifdef CONFIG_GOLDFISH_TTY_EARLY_CONSOLE
 438 static void gf_early_console_putchar(struct uart_port *port, int ch)
 439 {
 440         __raw_writel(ch, port->membase);
 441 }
 442
 443 static void gf_early_write(struct console *con, const char *s, unsigned int n)
 444 {
 445         struct earlycon_device *dev = con->data;
 446
 447         uart_console_write(&dev->port, s, n, gf_early_console_putchar);
 448 }
 449
 450 static int __init gf_earlycon_setup(struct earlycon_device *device,
 451                                     const char *opt)
 452 {
 453         if (!device->port.membase)
 454                 return -ENODEV;
 455
 456         device->con->write = gf_early_write;
 457         return 0;
 458 }
 459
 460 OF_EARLYCON_DECLARE(early_gf_tty, "google,goldfish-tty", gf_earlycon_setup);
 461 #endif
 462
 463 static const struct of_device_id goldfish_tty_of_match[] = {
 464         { .compatible = "google,goldfish-tty", },
 465         {},
 466 };
 467
 468 MODULE_DEVICE_TABLE(of, goldfish_tty_of_match);
 469
 470 static struct platform_driver goldfish_tty_platform_driver = {
 471         .probe = goldfish_tty_probe,
 472         .remove = goldfish_tty_remove,
 473         .driver = {
 474                 .name = "goldfish_tty",
 475                 .of_match_table = goldfish_tty_of_match,
 476         }
 477 };
 478
 479 module_platform_driver(goldfish_tty_platform_driver);
 480
 481 MODULE_LICENSE("GPL v2");