xref: /kernel/linux/linux-5.10/drivers/tty/goldfish.c (revision 8c2ecf20) 
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
36struct 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
47static DEFINE_MUTEX(goldfish_tty_lock);
48static struct tty_driver *goldfish_tty_driver;
49static u32 goldfish_tty_line_count = 8;
50static u32 goldfish_tty_current_line_count;
51static struct goldfish_tty *goldfish_ttys;
52
53static 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
76static 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
128static 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
137static 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_flip_buffer_push(&qtty->port);
155	return IRQ_HANDLED;
156}
157
158static 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
166static 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
173static 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
179static void goldfish_tty_close(struct tty_struct *tty, struct file *filp)
180{
181	tty_port_close(tty->port, tty, filp);
182}
183
184static void goldfish_tty_hangup(struct tty_struct *tty)
185{
186	tty_port_hangup(tty->port);
187}
188
189static 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
196static int goldfish_tty_write_room(struct tty_struct *tty)
197{
198	return 0x10000;
199}
200
201static 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
208static 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
214static 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
221static 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
230static const struct tty_port_operations goldfish_port_ops = {
231	.activate = goldfish_tty_activate,
232	.shutdown = goldfish_tty_shutdown
233};
234
235static 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
244static 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
276err_tty_register_driver_failed:
277	put_tty_driver(tty);
278err_alloc_tty_driver_failed:
279	kfree(goldfish_ttys);
280	goldfish_ttys = NULL;
281err_alloc_goldfish_ttys_failed:
282	return ret;
283}
284
285static 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
294static 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
407err_tty_register_device_failed:
408	free_irq(irq, qtty);
409err_dec_line_count:
410	tty_port_destroy(&qtty->port);
411	goldfish_tty_current_line_count--;
412	if (goldfish_tty_current_line_count == 0)
413		goldfish_tty_delete_driver();
414err_unlock:
415	mutex_unlock(&goldfish_tty_lock);
416err_unmap:
417	iounmap(base);
418	return ret;
419}
420
421static int goldfish_tty_remove(struct platform_device *pdev)
422{
423	struct goldfish_tty *qtty = platform_get_drvdata(pdev);
424
425	mutex_lock(&goldfish_tty_lock);
426
427	unregister_console(&qtty->console);
428	tty_unregister_device(goldfish_tty_driver, qtty->console.index);
429	iounmap(qtty->base);
430	qtty->base = NULL;
431	free_irq(qtty->irq, qtty);
432	tty_port_destroy(&qtty->port);
433	goldfish_tty_current_line_count--;
434	if (goldfish_tty_current_line_count == 0)
435		goldfish_tty_delete_driver();
436	mutex_unlock(&goldfish_tty_lock);
437	return 0;
438}
439
440#ifdef CONFIG_GOLDFISH_TTY_EARLY_CONSOLE
441static void gf_early_console_putchar(struct uart_port *port, int ch)
442{
443	__raw_writel(ch, port->membase);
444}
445
446static void gf_early_write(struct console *con, const char *s, unsigned int n)
447{
448	struct earlycon_device *dev = con->data;
449
450	uart_console_write(&dev->port, s, n, gf_early_console_putchar);
451}
452
453static int __init gf_earlycon_setup(struct earlycon_device *device,
454				    const char *opt)
455{
456	if (!device->port.membase)
457		return -ENODEV;
458
459	device->con->write = gf_early_write;
460	return 0;
461}
462
463OF_EARLYCON_DECLARE(early_gf_tty, "google,goldfish-tty", gf_earlycon_setup);
464#endif
465
466static const struct of_device_id goldfish_tty_of_match[] = {
467	{ .compatible = "google,goldfish-tty", },
468	{},
469};
470
471MODULE_DEVICE_TABLE(of, goldfish_tty_of_match);
472
473static struct platform_driver goldfish_tty_platform_driver = {
474	.probe = goldfish_tty_probe,
475	.remove = goldfish_tty_remove,
476	.driver = {
477		.name = "goldfish_tty",
478		.of_match_table = goldfish_tty_of_match,
479	}
480};
481
482module_platform_driver(goldfish_tty_platform_driver);
483
484MODULE_LICENSE("GPL v2");
485