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, unsigned long address,
54		     size_t count, bool is_write)
55{
56	unsigned long irq_flags;
57	void __iomem *base = qtty->base;
58
59	spin_lock_irqsave(&qtty->lock, irq_flags);
60	gf_write_ptr((void *)address, base + GOLDFISH_TTY_REG_DATA_PTR,
61		     base + GOLDFISH_TTY_REG_DATA_PTR_HIGH);
62	gf_iowrite32(count, base + GOLDFISH_TTY_REG_DATA_LEN);
63
64	if (is_write)
65		gf_iowrite32(GOLDFISH_TTY_CMD_WRITE_BUFFER,
66		       base + GOLDFISH_TTY_REG_CMD);
67	else
68		gf_iowrite32(GOLDFISH_TTY_CMD_READ_BUFFER,
69		       base + GOLDFISH_TTY_REG_CMD);
70
71	spin_unlock_irqrestore(&qtty->lock, irq_flags);
72}
73
74static void goldfish_tty_rw(struct goldfish_tty *qtty, unsigned long addr,
75			    size_t count, bool is_write)
76{
77	dma_addr_t dma_handle;
78	enum dma_data_direction dma_dir;
79
80	dma_dir = (is_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
81	if (qtty->version > 0) {
82		/*
83		 * Goldfish TTY for Ranchu platform uses
84		 * physical addresses and DMA for read/write operations
85		 */
86		unsigned long addr_end = addr + count;
87
88		while (addr < addr_end) {
89			unsigned long pg_end = (addr & PAGE_MASK) + PAGE_SIZE;
90			unsigned long next =
91					pg_end < addr_end ? pg_end : addr_end;
92			unsigned long avail = next - addr;
93
94			/*
95			 * Map the buffer's virtual address to the DMA address
96			 * so the buffer can be accessed by the device.
97			 */
98			dma_handle = dma_map_single(qtty->dev, (void *)addr,
99						    avail, dma_dir);
100
101			if (dma_mapping_error(qtty->dev, dma_handle)) {
102				dev_err(qtty->dev, "tty: DMA mapping error.\n");
103				return;
104			}
105			do_rw_io(qtty, dma_handle, avail, is_write);
106
107			/*
108			 * Unmap the previously mapped region after
109			 * the completion of the read/write operation.
110			 */
111			dma_unmap_single(qtty->dev, dma_handle, avail, dma_dir);
112
113			addr += avail;
114		}
115	} else {
116		/*
117		 * Old style Goldfish TTY used on the Goldfish platform
118		 * uses virtual addresses.
119		 */
120		do_rw_io(qtty, addr, count, is_write);
121	}
122}
123
124static void goldfish_tty_do_write(int line, const u8 *buf, size_t count)
125{
126	struct goldfish_tty *qtty = &goldfish_ttys[line];
127
128	goldfish_tty_rw(qtty, (unsigned long)buf, count, true);
129}
130
131static irqreturn_t goldfish_tty_interrupt(int irq, void *dev_id)
132{
133	struct goldfish_tty *qtty = dev_id;
134	void __iomem *base = qtty->base;
135	u8 *buf;
136	u32 count;
137
138	count = gf_ioread32(base + GOLDFISH_TTY_REG_BYTES_READY);
139	if (count == 0)
140		return IRQ_NONE;
141
142	count = tty_prepare_flip_string(&qtty->port, &buf, count);
143
144	goldfish_tty_rw(qtty, (unsigned long)buf, count, false);
145
146	tty_flip_buffer_push(&qtty->port);
147	return IRQ_HANDLED;
148}
149
150static int goldfish_tty_activate(struct tty_port *port, struct tty_struct *tty)
151{
152	struct goldfish_tty *qtty = container_of(port, struct goldfish_tty,
153									port);
154	gf_iowrite32(GOLDFISH_TTY_CMD_INT_ENABLE, qtty->base + GOLDFISH_TTY_REG_CMD);
155	return 0;
156}
157
158static void goldfish_tty_shutdown(struct tty_port *port)
159{
160	struct goldfish_tty *qtty = container_of(port, struct goldfish_tty,
161									port);
162	gf_iowrite32(GOLDFISH_TTY_CMD_INT_DISABLE, qtty->base + GOLDFISH_TTY_REG_CMD);
163}
164
165static int goldfish_tty_open(struct tty_struct *tty, struct file *filp)
166{
167	struct goldfish_tty *qtty = &goldfish_ttys[tty->index];
168	return tty_port_open(&qtty->port, tty, filp);
169}
170
171static void goldfish_tty_close(struct tty_struct *tty, struct file *filp)
172{
173	tty_port_close(tty->port, tty, filp);
174}
175
176static void goldfish_tty_hangup(struct tty_struct *tty)
177{
178	tty_port_hangup(tty->port);
179}
180
181static ssize_t goldfish_tty_write(struct tty_struct *tty, const u8 *buf,
182				  size_t count)
183{
184	goldfish_tty_do_write(tty->index, buf, count);
185	return count;
186}
187
188static unsigned int goldfish_tty_write_room(struct tty_struct *tty)
189{
190	return 0x10000;
191}
192
193static unsigned int goldfish_tty_chars_in_buffer(struct tty_struct *tty)
194{
195	struct goldfish_tty *qtty = &goldfish_ttys[tty->index];
196	void __iomem *base = qtty->base;
197	return gf_ioread32(base + GOLDFISH_TTY_REG_BYTES_READY);
198}
199
200static void goldfish_tty_console_write(struct console *co, const char *b,
201								unsigned count)
202{
203	goldfish_tty_do_write(co->index, b, count);
204}
205
206static struct tty_driver *goldfish_tty_console_device(struct console *c,
207								int *index)
208{
209	*index = c->index;
210	return goldfish_tty_driver;
211}
212
213static int goldfish_tty_console_setup(struct console *co, char *options)
214{
215	if ((unsigned)co->index >= goldfish_tty_line_count)
216		return -ENODEV;
217	if (!goldfish_ttys[co->index].base)
218		return -ENODEV;
219	return 0;
220}
221
222static const struct tty_port_operations goldfish_port_ops = {
223	.activate = goldfish_tty_activate,
224	.shutdown = goldfish_tty_shutdown
225};
226
227static const struct tty_operations goldfish_tty_ops = {
228	.open = goldfish_tty_open,
229	.close = goldfish_tty_close,
230	.hangup = goldfish_tty_hangup,
231	.write = goldfish_tty_write,
232	.write_room = goldfish_tty_write_room,
233	.chars_in_buffer = goldfish_tty_chars_in_buffer,
234};
235
236static int goldfish_tty_create_driver(void)
237{
238	int ret;
239	struct tty_driver *tty;
240
241	goldfish_ttys = kcalloc(goldfish_tty_line_count,
242				sizeof(*goldfish_ttys),
243				GFP_KERNEL);
244	if (goldfish_ttys == NULL) {
245		ret = -ENOMEM;
246		goto err_alloc_goldfish_ttys_failed;
247	}
248	tty = tty_alloc_driver(goldfish_tty_line_count,
249			TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
250			TTY_DRIVER_DYNAMIC_DEV);
251	if (IS_ERR(tty)) {
252		ret = PTR_ERR(tty);
253		goto err_tty_alloc_driver_failed;
254	}
255	tty->driver_name = "goldfish";
256	tty->name = "ttyGF";
257	tty->type = TTY_DRIVER_TYPE_SERIAL;
258	tty->subtype = SERIAL_TYPE_NORMAL;
259	tty->init_termios = tty_std_termios;
260	tty_set_operations(tty, &goldfish_tty_ops);
261	ret = tty_register_driver(tty);
262	if (ret)
263		goto err_tty_register_driver_failed;
264
265	goldfish_tty_driver = tty;
266	return 0;
267
268err_tty_register_driver_failed:
269	tty_driver_kref_put(tty);
270err_tty_alloc_driver_failed:
271	kfree(goldfish_ttys);
272	goldfish_ttys = NULL;
273err_alloc_goldfish_ttys_failed:
274	return ret;
275}
276
277static void goldfish_tty_delete_driver(void)
278{
279	tty_unregister_driver(goldfish_tty_driver);
280	tty_driver_kref_put(goldfish_tty_driver);
281	goldfish_tty_driver = NULL;
282	kfree(goldfish_ttys);
283	goldfish_ttys = NULL;
284}
285
286static int goldfish_tty_probe(struct platform_device *pdev)
287{
288	struct goldfish_tty *qtty;
289	int ret = -ENODEV;
290	struct resource *r;
291	struct device *ttydev;
292	void __iomem *base;
293	int irq;
294	unsigned int line;
295
296	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
297	if (!r) {
298		pr_err("goldfish_tty: No MEM resource available!\n");
299		return -ENOMEM;
300	}
301
302	base = ioremap(r->start, 0x1000);
303	if (!base) {
304		pr_err("goldfish_tty: Unable to ioremap base!\n");
305		return -ENOMEM;
306	}
307
308	irq = platform_get_irq(pdev, 0);
309	if (irq < 0) {
310		ret = irq;
311		goto err_unmap;
312	}
313
314	mutex_lock(&goldfish_tty_lock);
315
316	if (pdev->id == PLATFORM_DEVID_NONE)
317		line = goldfish_tty_current_line_count;
318	else
319		line = pdev->id;
320
321	if (line >= goldfish_tty_line_count) {
322		pr_err("goldfish_tty: Reached maximum tty number of %d.\n",
323		       goldfish_tty_current_line_count);
324		ret = -ENOMEM;
325		goto err_unlock;
326	}
327
328	if (goldfish_tty_current_line_count == 0) {
329		ret = goldfish_tty_create_driver();
330		if (ret)
331			goto err_unlock;
332	}
333	goldfish_tty_current_line_count++;
334
335	qtty = &goldfish_ttys[line];
336	spin_lock_init(&qtty->lock);
337	tty_port_init(&qtty->port);
338	qtty->port.ops = &goldfish_port_ops;
339	qtty->base = base;
340	qtty->irq = irq;
341	qtty->dev = &pdev->dev;
342
343	/*
344	 * Goldfish TTY device used by the Goldfish emulator
345	 * should identify itself with 0, forcing the driver
346	 * to use virtual addresses. Goldfish TTY device
347	 * on Ranchu emulator (qemu2) returns 1 here and
348	 * driver will use physical addresses.
349	 */
350	qtty->version = gf_ioread32(base + GOLDFISH_TTY_REG_VERSION);
351
352	/*
353	 * Goldfish TTY device on Ranchu emulator (qemu2)
354	 * will use DMA for read/write IO operations.
355	 */
356	if (qtty->version > 0) {
357		/*
358		 * Initialize dma_mask to 32-bits.
359		 */
360		if (!pdev->dev.dma_mask)
361			pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
362		ret = dma_set_mask(&pdev->dev, DMA_BIT_MASK(32));
363		if (ret) {
364			dev_err(&pdev->dev, "No suitable DMA available.\n");
365			goto err_dec_line_count;
366		}
367	}
368
369	gf_iowrite32(GOLDFISH_TTY_CMD_INT_DISABLE, base + GOLDFISH_TTY_REG_CMD);
370
371	ret = request_irq(irq, goldfish_tty_interrupt, IRQF_SHARED,
372			  "goldfish_tty", qtty);
373	if (ret) {
374		pr_err("goldfish_tty: No IRQ available!\n");
375		goto err_dec_line_count;
376	}
377
378	ttydev = tty_port_register_device(&qtty->port, goldfish_tty_driver,
379					  line, &pdev->dev);
380	if (IS_ERR(ttydev)) {
381		ret = PTR_ERR(ttydev);
382		goto err_tty_register_device_failed;
383	}
384
385	strcpy(qtty->console.name, "ttyGF");
386	qtty->console.write = goldfish_tty_console_write;
387	qtty->console.device = goldfish_tty_console_device;
388	qtty->console.setup = goldfish_tty_console_setup;
389	qtty->console.flags = CON_PRINTBUFFER;
390	qtty->console.index = line;
391	register_console(&qtty->console);
392	platform_set_drvdata(pdev, qtty);
393
394	mutex_unlock(&goldfish_tty_lock);
395	return 0;
396
397err_tty_register_device_failed:
398	free_irq(irq, qtty);
399err_dec_line_count:
400	tty_port_destroy(&qtty->port);
401	goldfish_tty_current_line_count--;
402	if (goldfish_tty_current_line_count == 0)
403		goldfish_tty_delete_driver();
404err_unlock:
405	mutex_unlock(&goldfish_tty_lock);
406err_unmap:
407	iounmap(base);
408	return ret;
409}
410
411static void goldfish_tty_remove(struct platform_device *pdev)
412{
413	struct goldfish_tty *qtty = platform_get_drvdata(pdev);
414
415	mutex_lock(&goldfish_tty_lock);
416
417	unregister_console(&qtty->console);
418	tty_unregister_device(goldfish_tty_driver, qtty->console.index);
419	iounmap(qtty->base);
420	qtty->base = NULL;
421	free_irq(qtty->irq, qtty);
422	tty_port_destroy(&qtty->port);
423	goldfish_tty_current_line_count--;
424	if (goldfish_tty_current_line_count == 0)
425		goldfish_tty_delete_driver();
426	mutex_unlock(&goldfish_tty_lock);
427}
428
429#ifdef CONFIG_GOLDFISH_TTY_EARLY_CONSOLE
430static void gf_early_console_putchar(struct uart_port *port, unsigned char ch)
431{
432	gf_iowrite32(ch, port->membase);
433}
434
435static void gf_early_write(struct console *con, const char *s, unsigned int n)
436{
437	struct earlycon_device *dev = con->data;
438
439	uart_console_write(&dev->port, s, n, gf_early_console_putchar);
440}
441
442static int __init gf_earlycon_setup(struct earlycon_device *device,
443				    const char *opt)
444{
445	if (!device->port.membase)
446		return -ENODEV;
447
448	device->con->write = gf_early_write;
449	return 0;
450}
451
452OF_EARLYCON_DECLARE(early_gf_tty, "google,goldfish-tty", gf_earlycon_setup);
453#endif
454
455static const struct of_device_id goldfish_tty_of_match[] = {
456	{ .compatible = "google,goldfish-tty", },
457	{},
458};
459
460MODULE_DEVICE_TABLE(of, goldfish_tty_of_match);
461
462static struct platform_driver goldfish_tty_platform_driver = {
463	.probe = goldfish_tty_probe,
464	.remove_new = goldfish_tty_remove,
465	.driver = {
466		.name = "goldfish_tty",
467		.of_match_table = goldfish_tty_of_match,
468	}
469};
470
471module_platform_driver(goldfish_tty_platform_driver);
472
473MODULE_LICENSE("GPL v2");
474