[linux-block.git] / drivers / tty / goldfish.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,
		     unsigned int count,
		     int 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);
	writel(count, base + GOLDFISH_TTY_REG_DATA_LEN);

	if (is_write)
		writel(GOLDFISH_TTY_CMD_WRITE_BUFFER,
		       base + GOLDFISH_TTY_REG_CMD);
	else
		writel(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,
			    unsigned int count,
			    int 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 char *buf,
				  unsigned int count)
{
	struct goldfish_tty *qtty = &goldfish_ttys[line];
	unsigned long address = (unsigned long)(void *)buf;

	goldfish_tty_rw(qtty, address, count, 1);
}

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

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

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

	address = (unsigned long)(void *)buf;
	goldfish_tty_rw(qtty, address, count, 0);

	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_REG_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_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 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_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 = 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 = -ENODEV;
	struct resource *r;
	struct device *ttydev;
	void __iomem *base;
	u32 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;
	}

	r = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
	if (!r) {
		pr_err("goldfish_tty: No IRQ resource available!\n");
		goto err_unmap;
	}

	irq = r->start;

	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 = readl(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;
		}
	}

	writel(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:
	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 int 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, pdev);
	goldfish_tty_current_line_count--;
	if (goldfish_tty_current_line_count == 0)
		goldfish_tty_delete_driver();
	mutex_unlock(&goldfish_tty_lock);
	return 0;
}

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