Quelle  goldfish.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2007 Google, Inc.
 * Copyright (C) 2012 Intel, Inc.
 * Copyright (C) 2017 Imagination Technologies Ltd.
 */

#include <linux/console.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/goldfish.h>
#include <linux/mm.h>
#include <linux/dma-mapping.h>
#include <linux/serial_core.h>

/* Goldfish tty register's offsets */
#define GOLDFISH_TTY_REG_BYTES_READY 0x04
#define GOLDFISH_TTY_REG_CMD  0x08
#define GOLDFISH_TTY_REG_DATA_PTR 0x10
#define GOLDFISH_TTY_REG_DATA_LEN 0x14
#define GOLDFISH_TTY_REG_DATA_PTR_HIGH 0x18
#define GOLDFISH_TTY_REG_VERSION 0x20

/* Goldfish tty commands */
#define GOLDFISH_TTY_CMD_INT_DISABLE 0
#define GOLDFISH_TTY_CMD_INT_ENABLE 1
#define GOLDFISH_TTY_CMD_WRITE_BUFFER 2
#define GOLDFISH_TTY_CMD_READ_BUFFER 3

struct goldfish_tty {
 struct tty_port port;
 spinlock_t lock;
 void __iomem *base;
 u32 irq;
 int opencount;
 struct console console;
 u32 version;
 struct device *dev;
};

static DEFINE_MUTEX(goldfish_tty_lock);
static struct tty_driver *goldfish_tty_driver;
static u32 goldfish_tty_line_count = 8;
static u32 goldfish_tty_current_line_count;
static struct goldfish_tty *goldfish_ttys;

static void do_rw_io(struct goldfish_tty *qtty, unsigned long address,
       size_t count, bool is_write)
{
 unsigned long irq_flags;
 void __iomem *base = qtty->base;

 spin_lock_irqsave(&qtty->lock, irq_flags);
 gf_write_ptr((void *)address, base + GOLDFISH_TTY_REG_DATA_PTR,
       base + GOLDFISH_TTY_REG_DATA_PTR_HIGH);
 gf_iowrite32(count, base + GOLDFISH_TTY_REG_DATA_LEN);

 if (is_write)
  gf_iowrite32(GOLDFISH_TTY_CMD_WRITE_BUFFER,
         base + GOLDFISH_TTY_REG_CMD);
 else
  gf_iowrite32(GOLDFISH_TTY_CMD_READ_BUFFER,
         base + GOLDFISH_TTY_REG_CMD);

 spin_unlock_irqrestore(&qtty->lock, irq_flags);
}

static void goldfish_tty_rw(struct goldfish_tty *qtty, unsigned long addr,
       size_t count, bool is_write)
{
 dma_addr_t dma_handle;
 enum dma_data_direction dma_dir;

 dma_dir = (is_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
 if (qtty->version > 0) {
  /*
 * Goldfish TTY for Ranchu platform uses
 * physical addresses and DMA for read/write operations
 */
  unsigned long addr_end = addr + count;

  while (addr < addr_end) {
   unsigned long pg_end = (addr & PAGE_MASK) + PAGE_SIZE;
   unsigned long next =
     pg_end < addr_end ? pg_end : addr_end;
   unsigned long avail = next - addr;

   /*
 * Map the buffer's virtual address to the DMA address
 * so the buffer can be accessed by the device.
 */
   dma_handle = dma_map_single(qtty->dev, (void *)addr,
          avail, dma_dir);

   if (dma_mapping_error(qtty->dev, dma_handle)) {
    dev_err(qtty->dev, "tty: DMA mapping error.\n");
    return;
   }
   do_rw_io(qtty, dma_handle, avail, is_write);

   /*
 * Unmap the previously mapped region after
 * the completion of the read/write operation.
 */
   dma_unmap_single(qtty->dev, dma_handle, avail, dma_dir);

   addr += avail;
  }
 } else {
  /*
 * Old style Goldfish TTY used on the Goldfish platform
 * uses virtual addresses.
 */
  do_rw_io(qtty, addr, count, is_write);
 }
}

static void goldfish_tty_do_write(int line, const u8 *buf, size_t count)
{
 struct goldfish_tty *qtty = &goldfish_ttys[line];

 goldfish_tty_rw(qtty, (unsigned long)buf, count, true);
}

static irqreturn_t goldfish_tty_interrupt(int irq, void *dev_id)
{
 struct goldfish_tty *qtty = dev_id;
 void __iomem *base = qtty->base;
 u8 *buf;
 u32 count;

 count = gf_ioread32(base + GOLDFISH_TTY_REG_BYTES_READY);
 if (count == 0)
  return IRQ_NONE;

 count = tty_prepare_flip_string(&qtty->port, &buf, count);

 goldfish_tty_rw(qtty, (unsigned long)buf, count, false);

 tty_flip_buffer_push(&qtty->port);
 return IRQ_HANDLED;
}

static int goldfish_tty_activate(struct tty_port *port, struct tty_struct *tty)
{
 struct goldfish_tty *qtty = container_of(port, struct goldfish_tty,
         port);
 gf_iowrite32(GOLDFISH_TTY_CMD_INT_ENABLE, qtty->base + GOLDFISH_TTY_REG_CMD);
 return 0;
}

static void goldfish_tty_shutdown(struct tty_port *port)
{
 struct goldfish_tty *qtty = container_of(port, struct goldfish_tty,
         port);
 gf_iowrite32(GOLDFISH_TTY_CMD_INT_DISABLE, qtty->base + GOLDFISH_TTY_REG_CMD);
}

static int goldfish_tty_open(struct tty_struct *tty, struct file *filp)
{
 struct goldfish_tty *qtty = &goldfish_ttys[tty->index];
 return tty_port_open(&qtty->port, tty, filp);
}

static void goldfish_tty_close(struct tty_struct *tty, struct file *filp)
{
 tty_port_close(tty->port, tty, filp);
}

static void goldfish_tty_hangup(struct tty_struct *tty)
{
 tty_port_hangup(tty->port);
}

static ssize_t goldfish_tty_write(struct tty_struct *tty, const u8 *buf,
      size_t count)
{
 goldfish_tty_do_write(tty->index, buf, count);
 return count;
}

static unsigned int goldfish_tty_write_room(struct tty_struct *tty)
{
 return 0x10000;
}

static unsigned int goldfish_tty_chars_in_buffer(struct tty_struct *tty)
{
 struct goldfish_tty *qtty = &goldfish_ttys[tty->index];
 void __iomem *base = qtty->base;
 return gf_ioread32(base + GOLDFISH_TTY_REG_BYTES_READY);
}

static void goldfish_tty_console_write(struct console *co, const char *b,
        unsigned count)
{
 goldfish_tty_do_write(co->index, b, count);
}

static struct tty_driver *goldfish_tty_console_device(struct console *c,
        int *index)
{
 *index = c->index;
 return goldfish_tty_driver;
}

static int goldfish_tty_console_setup(struct console *co, char *options)
{
 if ((unsigned)co->index >= goldfish_tty_line_count)
  return -ENODEV;
 if (!goldfish_ttys[co->index].base)
  return -ENODEV;
 return 0;
}

static const struct tty_port_operations goldfish_port_ops = {
 .activate = goldfish_tty_activate,
 .shutdown = goldfish_tty_shutdown
};

static const struct tty_operations goldfish_tty_ops = {
 .open = goldfish_tty_open,
 .close = goldfish_tty_close,
 .hangup = goldfish_tty_hangup,
 .write = goldfish_tty_write,
 .write_room = goldfish_tty_write_room,
 .chars_in_buffer = goldfish_tty_chars_in_buffer,
};

static int goldfish_tty_create_driver(void)
{
 int ret;
 struct tty_driver *tty;

 goldfish_ttys = kcalloc(goldfish_tty_line_count,
    sizeof(*goldfish_ttys),
    GFP_KERNEL);
 if (goldfish_ttys == NULL) {
  ret = -ENOMEM;
  goto err_alloc_goldfish_ttys_failed;
 }
 tty = tty_alloc_driver(goldfish_tty_line_count,
   TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
   TTY_DRIVER_DYNAMIC_DEV);
 if (IS_ERR(tty)) {
  ret = PTR_ERR(tty);
  goto err_tty_alloc_driver_failed;
 }
 tty->driver_name = "goldfish";
 tty->name = "ttyGF";
 tty->type = TTY_DRIVER_TYPE_SERIAL;
 tty->subtype = SERIAL_TYPE_NORMAL;
 tty->init_termios = tty_std_termios;
 tty_set_operations(tty, &goldfish_tty_ops);
 ret = tty_register_driver(tty);
 if (ret)
  goto err_tty_register_driver_failed;

 goldfish_tty_driver = tty;
 return 0;

err_tty_register_driver_failed:
 tty_driver_kref_put(tty);
err_tty_alloc_driver_failed:
 kfree(goldfish_ttys);
 goldfish_ttys = NULL;
err_alloc_goldfish_ttys_failed:
 return ret;
}

static void goldfish_tty_delete_driver(void)
{
 tty_unregister_driver(goldfish_tty_driver);
 tty_driver_kref_put(goldfish_tty_driver);
 goldfish_tty_driver = NULL;
 kfree(goldfish_ttys);
 goldfish_ttys = NULL;
}

static int goldfish_tty_probe(struct platform_device *pdev)
{
 struct goldfish_tty *qtty;
 int ret = -ENODEV;
 struct resource *r;
 struct device *ttydev;
 void __iomem *base;
 int irq;
 unsigned int line;

 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 if (!r) {
  pr_err("goldfish_tty: No MEM resource available!\n");
  return -ENOMEM;
 }

 base = ioremap(r->start, 0x1000);
 if (!base) {
  pr_err("goldfish_tty: Unable to ioremap base!\n");
  return -ENOMEM;
 }

 irq = platform_get_irq(pdev, 0);
 if (irq < 0) {
  ret = irq;
  goto err_unmap;
 }

 mutex_lock(&goldfish_tty_lock);

 if (pdev->id == PLATFORM_DEVID_NONE)
  line = goldfish_tty_current_line_count;
 else
  line = pdev->id;

 if (line >= goldfish_tty_line_count) {
  pr_err("goldfish_tty: Reached maximum tty number of %d.\n",
         goldfish_tty_current_line_count);
  ret = -ENOMEM;
  goto err_unlock;
 }

 if (goldfish_tty_current_line_count == 0) {
  ret = goldfish_tty_create_driver();
  if (ret)
   goto err_unlock;
 }
 goldfish_tty_current_line_count++;

 qtty = &goldfish_ttys[line];
 spin_lock_init(&qtty->lock);
 tty_port_init(&qtty->port);
 qtty->port.ops = &goldfish_port_ops;
 qtty->base = base;
 qtty->irq = irq;
 qtty->dev = &pdev->dev;

 /*
 * Goldfish TTY device used by the Goldfish emulator
 * should identify itself with 0, forcing the driver
 * to use virtual addresses. Goldfish TTY device
 * on Ranchu emulator (qemu2) returns 1 here and
 * driver will use physical addresses.
 */
 qtty->version = gf_ioread32(base + GOLDFISH_TTY_REG_VERSION);

 /*
 * Goldfish TTY device on Ranchu emulator (qemu2)
 * will use DMA for read/write IO operations.
 */
 if (qtty->version > 0) {
  /*
 * Initialize dma_mask to 32-bits.
 */
  if (!pdev->dev.dma_mask)
   pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
  ret = dma_set_mask(&pdev->dev, DMA_BIT_MASK(32));
  if (ret) {
   dev_err(&pdev->dev, "No suitable DMA available.\n");
   goto err_dec_line_count;
  }
 }

 gf_iowrite32(GOLDFISH_TTY_CMD_INT_DISABLE, base + GOLDFISH_TTY_REG_CMD);

 ret = request_irq(irq, goldfish_tty_interrupt, IRQF_SHARED,
     "goldfish_tty", qtty);
 if (ret) {
  pr_err("goldfish_tty: No IRQ available!\n");
  goto err_dec_line_count;
 }

 ttydev = tty_port_register_device(&qtty->port, goldfish_tty_driver,
       line, &pdev->dev);
 if (IS_ERR(ttydev)) {
  ret = PTR_ERR(ttydev);
  goto err_tty_register_device_failed;
 }

 strcpy(qtty->console.name, "ttyGF");
 qtty->console.write = goldfish_tty_console_write;
 qtty->console.device = goldfish_tty_console_device;
 qtty->console.setup = goldfish_tty_console_setup;
 qtty->console.flags = CON_PRINTBUFFER;
 qtty->console.index = line;
 register_console(&qtty->console);
 platform_set_drvdata(pdev, qtty);

 mutex_unlock(&goldfish_tty_lock);
 return 0;

err_tty_register_device_failed:
 free_irq(irq, qtty);
err_dec_line_count:
 tty_port_destroy(&qtty->port);
 goldfish_tty_current_line_count--;
 if (goldfish_tty_current_line_count == 0)
  goldfish_tty_delete_driver();
err_unlock:
 mutex_unlock(&goldfish_tty_lock);
err_unmap:
 iounmap(base);
 return ret;
}

static void goldfish_tty_remove(struct platform_device *pdev)
{
 struct goldfish_tty *qtty = platform_get_drvdata(pdev);

 mutex_lock(&goldfish_tty_lock);

 unregister_console(&qtty->console);
 tty_unregister_device(goldfish_tty_driver, qtty->console.index);
 iounmap(qtty->base);
 qtty->base = NULL;
 free_irq(qtty->irq, qtty);
 tty_port_destroy(&qtty->port);
 goldfish_tty_current_line_count--;
 if (goldfish_tty_current_line_count == 0)
  goldfish_tty_delete_driver();
 mutex_unlock(&goldfish_tty_lock);
}

#ifdef CONFIG_GOLDFISH_TTY_EARLY_CONSOLE
static void gf_early_console_putchar(struct uart_port *port, unsigned char ch)
{
 gf_iowrite32(ch, port->membase);
}

static void gf_early_write(struct console *con, const char *s, unsigned int n)
{
 struct earlycon_device *dev = con->data;

 uart_console_write(&dev->port, s, n, gf_early_console_putchar);
}

static int __init gf_earlycon_setup(struct earlycon_device *device,
        const char *opt)
{
 if (!device->port.membase)
  return -ENODEV;

 device->con->write = gf_early_write;
 return 0;
}

OF_EARLYCON_DECLARE(early_gf_tty, "google,goldfish-tty", gf_earlycon_setup);
#endif

static const struct of_device_id goldfish_tty_of_match[] = {
 { .compatible = "google,goldfish-tty", },
 {},
};

MODULE_DEVICE_TABLE(of, goldfish_tty_of_match);

static struct platform_driver goldfish_tty_platform_driver = {
 .probe = goldfish_tty_probe,
 .remove = goldfish_tty_remove,
 .driver = {
  .name = "goldfish_tty",
  .of_match_table = goldfish_tty_of_match,
 }
};

module_platform_driver(goldfish_tty_platform_driver);

MODULE_DESCRIPTION("Goldfish TTY Driver");
MODULE_LICENSE("GPL v2");