/*
   * Copyright (C) 2007 Google, Inc.
   * Copyright (C) 2012 Intel, Inc.
   *
   * This software is licensed under the terms of the GNU General Public
   * License version 2, as published by the Free Software Foundation, and
   * may be copied, distributed, and modified under those terms.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   */
  
  #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>
  
  enum {
  	GOLDFISH_TTY_PUT_CHAR       = 0x00,
  	GOLDFISH_TTY_BYTES_READY    = 0x04,
  	GOLDFISH_TTY_CMD            = 0x08,
  
  	GOLDFISH_TTY_DATA_PTR       = 0x10,
  	GOLDFISH_TTY_DATA_LEN       = 0x14,
  
  	GOLDFISH_TTY_CMD_INT_DISABLE    = 0,
  	GOLDFISH_TTY_CMD_INT_ENABLE     = 1,
  	GOLDFISH_TTY_CMD_WRITE_BUFFER   = 2,
  	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;
  };
  
  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 goldfish_tty_do_write(int line, const char *buf, unsigned count)
  {
  	unsigned long irq_flags;
  	struct goldfish_tty *qtty = &goldfish_ttys[line];
  	void __iomem *base = qtty->base;
  	spin_lock_irqsave(&qtty->lock, irq_flags);
  	writel((u32)buf, base + GOLDFISH_TTY_DATA_PTR);
  	writel(count, base + GOLDFISH_TTY_DATA_LEN);
  	writel(GOLDFISH_TTY_CMD_WRITE_BUFFER, base + GOLDFISH_TTY_CMD);
  	spin_unlock_irqrestore(&qtty->lock, irq_flags);
  }
  
  static irqreturn_t goldfish_tty_interrupt(int irq, void *dev_id)
  {
  	struct platform_device *pdev = dev_id;
  	struct goldfish_tty *qtty = &goldfish_ttys[pdev->id];
  	void __iomem *base = qtty->base;
  	unsigned long irq_flags;
  	unsigned char *buf;
  	u32 count;
  
  	count = readl(base + GOLDFISH_TTY_BYTES_READY);
  	if(count == 0)
  		return IRQ_NONE;
  
  	count = tty_prepare_flip_string(&qtty->port, &buf, count);
  	spin_lock_irqsave(&qtty->lock, irq_flags);
  	writel((u32)buf, base + GOLDFISH_TTY_DATA_PTR);
  	writel(count, base + GOLDFISH_TTY_DATA_LEN);
  	writel(GOLDFISH_TTY_CMD_READ_BUFFER, base + GOLDFISH_TTY_CMD);
  	spin_unlock_irqrestore(&qtty->lock, irq_flags);
  	tty_schedule_flip(&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);
  	writel(GOLDFISH_TTY_CMD_INT_ENABLE, qtty->base + GOLDFISH_TTY_CMD);
  	return 0;
  }
  
  static void goldfish_tty_shutdown(struct tty_port *port)
  {
  	struct goldfish_tty *qtty = container_of(port, struct goldfish_tty, port);
  	writel(GOLDFISH_TTY_CMD_INT_DISABLE, qtty->base + GOLDFISH_TTY_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 int goldfish_tty_write(struct tty_struct * tty, const unsigned char *buf, int count)
  {
  	goldfish_tty_do_write(tty->index, buf, count);
  	return count;
  }
  
  static int goldfish_tty_write_room(struct tty_struct *tty)
  {
  	return 0x10000;
  }
  
  static int goldfish_tty_chars_in_buffer(struct tty_struct *tty)
  {
  	struct goldfish_tty *qtty = &goldfish_ttys[tty->index];
  	void __iomem *base = qtty->base;
  	return readl(base + GOLDFISH_TTY_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 == 0)
  		return -ENODEV;
  	return 0;
  }
  
  static struct tty_port_operations goldfish_port_ops = {
  	.activate = goldfish_tty_activate,
  	.shutdown = goldfish_tty_shutdown
  };
  
  static 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 = kzalloc(sizeof(*goldfish_ttys) * goldfish_tty_line_count, GFP_KERNEL);
  	if(goldfish_ttys == NULL) {
  		ret = -ENOMEM;
  		goto err_alloc_goldfish_ttys_failed;
  	}
  	tty = alloc_tty_driver(goldfish_tty_line_count);
  	if(tty == NULL) {
  		ret = -ENOMEM;
  		goto err_alloc_tty_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->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
  	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:
  	put_tty_driver(tty);
  err_alloc_tty_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);
  	put_tty_driver(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 = -EINVAL;
  	int i;
  	struct resource *r;
  	struct device *ttydev;
  	void __iomem *base;
  	u32 irq;
  
  	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if(r == NULL)
  		return -EINVAL;
  
  	base = ioremap(r->start, 0x1000);
  	if (base == NULL)
  		pr_err("goldfish_tty: unable to remap base
  ");
  
  	r = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
  	if(r == NULL)
  		goto err_unmap;
  
  	irq = r->start;
  
  	if(pdev->id >= goldfish_tty_line_count)
  		goto err_unmap;
  
  	mutex_lock(&goldfish_tty_lock);
  	if(goldfish_tty_current_line_count == 0) {
  		ret = goldfish_tty_create_driver();
  		if(ret)
  			goto err_create_driver_failed;
  	}
  	goldfish_tty_current_line_count++;
  
  	qtty = &goldfish_ttys[pdev->id];
  	spin_lock_init(&qtty->lock);
  	tty_port_init(&qtty->port);
  	qtty->port.ops = &goldfish_port_ops;
  	qtty->base = base;
  	qtty->irq = irq;
  
  	writel(GOLDFISH_TTY_CMD_INT_DISABLE, base + GOLDFISH_TTY_CMD);
  
  	ret = request_irq(irq, goldfish_tty_interrupt, IRQF_SHARED, "goldfish_tty", pdev);
  	if(ret)
  		goto err_request_irq_failed;
  
  
  	ttydev = tty_port_register_device(&qtty->port, goldfish_tty_driver,
  							pdev->id, &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 = pdev->id;
  	register_console(&qtty->console);
  
  	mutex_unlock(&goldfish_tty_lock);
  	return 0;
  
  	tty_unregister_device(goldfish_tty_driver, i);
  err_tty_register_device_failed:
  	free_irq(irq, pdev);
  err_request_irq_failed:
  	goldfish_tty_current_line_count--;
  	if(goldfish_tty_current_line_count == 0)
  		goldfish_tty_delete_driver();
  err_create_driver_failed:
  	mutex_unlock(&goldfish_tty_lock);
  err_unmap:
  	iounmap(base);
  	return ret;
  }
  
  static int goldfish_tty_remove(struct platform_device *pdev)
  {
  	struct goldfish_tty *qtty;
  
  	mutex_lock(&goldfish_tty_lock);
  
  	qtty = &goldfish_ttys[pdev->id];
  	unregister_console(&qtty->console);
  	tty_unregister_device(goldfish_tty_driver, pdev->id);
  	iounmap(qtty->base);
  	qtty->base = 0;
  	free_irq(qtty->irq, pdev);
  	goldfish_tty_current_line_count--;
  	if(goldfish_tty_current_line_count == 0)
  		goldfish_tty_delete_driver();
  	mutex_unlock(&goldfish_tty_lock);
  	return 0;
  }
  
  static struct platform_driver goldfish_tty_platform_driver = {
  	.probe = goldfish_tty_probe,
  	.remove = goldfish_tty_remove,
  	.driver = {
  		.name = "goldfish_tty"
  	}
  };
  
  module_platform_driver(goldfish_tty_platform_driver);
  
  MODULE_LICENSE("GPL v2");