1// SPDX-License-Identifier: GPL-2.0-or-later
2
3#include <linux/bitfield.h>
4#include <linux/bits.h>
5#include <linux/console.h>
6#include <linux/delay.h>
7#include <linux/io.h>
8#include <linux/irq.h>
9#include <linux/module.h>
10#include <linux/of.h>
11#include <linux/platform_device.h>
12#include <linux/serial_core.h>
13#include <linux/slab.h>
14#include <linux/tty_flip.h>
15#include <asm/serial.h>
16
17#define DRIVER_NAME	"esp32s3-acm"
18#define DEV_NAME	"ttyGS"
19#define UART_NR		4
20
21#define ESP32S3_ACM_TX_FIFO_SIZE	64
22
23#define USB_SERIAL_JTAG_EP1_REG		0x00
24#define USB_SERIAL_JTAG_EP1_CONF_REG	0x04
25#define USB_SERIAL_JTAG_WR_DONE				BIT(0)
26#define USB_SERIAL_JTAG_SERIAL_IN_EP_DATA_FREE		BIT(1)
27#define USB_SERIAL_JTAG_INT_ST_REG	0x0c
28#define USB_SERIAL_JTAG_SERIAL_OUT_RECV_PKT_INT_ST	BIT(2)
29#define USB_SERIAL_JTAG_SERIAL_IN_EMPTY_INT_ST		BIT(3)
30#define USB_SERIAL_JTAG_INT_ENA_REG	0x10
31#define USB_SERIAL_JTAG_SERIAL_OUT_RECV_PKT_INT_ENA	BIT(2)
32#define USB_SERIAL_JTAG_SERIAL_IN_EMPTY_INT_ENA		BIT(3)
33#define USB_SERIAL_JTAG_INT_CLR_REG	0x14
34#define USB_SERIAL_JTAG_IN_EP1_ST_REG	0x2c
35#define USB_SERIAL_JTAG_IN_EP1_WR_ADDR			GENMASK(8, 2)
36#define USB_SERIAL_JTAG_OUT_EP1_ST_REG	0x3c
37#define USB_SERIAL_JTAG_OUT_EP1_REC_DATA_CNT		GENMASK(22, 16)
38
39static const struct of_device_id esp32s3_acm_dt_ids[] = {
40	{
41		.compatible = "esp,esp32s3-acm",
42	}, { /* sentinel */ }
43};
44MODULE_DEVICE_TABLE(of, esp32s3_acm_dt_ids);
45
46static struct uart_port *esp32s3_acm_ports[UART_NR];
47
48static void esp32s3_acm_write(struct uart_port *port, unsigned long reg, u32 v)
49{
50	writel(v, port->membase + reg);
51}
52
53static u32 esp32s3_acm_read(struct uart_port *port, unsigned long reg)
54{
55	return readl(port->membase + reg);
56}
57
58static u32 esp32s3_acm_tx_fifo_free(struct uart_port *port)
59{
60	u32 status = esp32s3_acm_read(port, USB_SERIAL_JTAG_EP1_CONF_REG);
61
62	return status & USB_SERIAL_JTAG_SERIAL_IN_EP_DATA_FREE;
63}
64
65static u32 esp32s3_acm_tx_fifo_cnt(struct uart_port *port)
66{
67	u32 status = esp32s3_acm_read(port, USB_SERIAL_JTAG_IN_EP1_ST_REG);
68
69	return FIELD_GET(USB_SERIAL_JTAG_IN_EP1_WR_ADDR, status);
70}
71
72static u32 esp32s3_acm_rx_fifo_cnt(struct uart_port *port)
73{
74	u32 status = esp32s3_acm_read(port, USB_SERIAL_JTAG_OUT_EP1_ST_REG);
75
76	return FIELD_GET(USB_SERIAL_JTAG_OUT_EP1_REC_DATA_CNT, status);
77}
78
79/* return TIOCSER_TEMT when transmitter is not busy */
80static unsigned int esp32s3_acm_tx_empty(struct uart_port *port)
81{
82	return esp32s3_acm_tx_fifo_cnt(port) == 0 ? TIOCSER_TEMT : 0;
83}
84
85static void esp32s3_acm_set_mctrl(struct uart_port *port, unsigned int mctrl)
86{
87}
88
89static unsigned int esp32s3_acm_get_mctrl(struct uart_port *port)
90{
91	return TIOCM_CAR;
92}
93
94static void esp32s3_acm_stop_tx(struct uart_port *port)
95{
96	u32 int_ena;
97
98	int_ena = esp32s3_acm_read(port, USB_SERIAL_JTAG_INT_ENA_REG);
99	int_ena &= ~USB_SERIAL_JTAG_SERIAL_IN_EMPTY_INT_ENA;
100	esp32s3_acm_write(port, USB_SERIAL_JTAG_INT_ENA_REG, int_ena);
101}
102
103static void esp32s3_acm_rxint(struct uart_port *port)
104{
105	struct tty_port *tty_port = &port->state->port;
106	u32 rx_fifo_cnt = esp32s3_acm_rx_fifo_cnt(port);
107	unsigned long flags;
108	u32 i;
109
110	if (!rx_fifo_cnt)
111		return;
112
113	spin_lock_irqsave(&port->lock, flags);
114
115	for (i = 0; i < rx_fifo_cnt; ++i) {
116		u32 rx = esp32s3_acm_read(port, USB_SERIAL_JTAG_EP1_REG);
117
118		++port->icount.rx;
119		tty_insert_flip_char(tty_port, rx, TTY_NORMAL);
120	}
121	spin_unlock_irqrestore(&port->lock, flags);
122
123	tty_flip_buffer_push(tty_port);
124}
125
126static void esp32s3_acm_push(struct uart_port *port)
127{
128	if (esp32s3_acm_tx_fifo_free(port))
129		esp32s3_acm_write(port, USB_SERIAL_JTAG_EP1_CONF_REG,
130				  USB_SERIAL_JTAG_WR_DONE);
131}
132
133static void esp32s3_acm_put_char(struct uart_port *port, u8 c)
134{
135	esp32s3_acm_write(port, USB_SERIAL_JTAG_EP1_REG, c);
136}
137
138static void esp32s3_acm_put_char_sync(struct uart_port *port, u8 c)
139{
140	unsigned long timeout = jiffies + HZ;
141
142	while (!esp32s3_acm_tx_fifo_free(port)) {
143		if (time_after(jiffies, timeout)) {
144			dev_warn(port->dev, "timeout waiting for TX FIFO\n");
145			return;
146		}
147		cpu_relax();
148	}
149	esp32s3_acm_put_char(port, c);
150	esp32s3_acm_push(port);
151}
152
153static void esp32s3_acm_transmit_buffer(struct uart_port *port)
154{
155	u32 tx_fifo_used;
156	unsigned int pending;
157	u8 ch;
158
159	if (!esp32s3_acm_tx_fifo_free(port))
160		return;
161
162	tx_fifo_used = esp32s3_acm_tx_fifo_cnt(port);
163	pending = uart_port_tx_limited(port, ch,
164				       ESP32S3_ACM_TX_FIFO_SIZE - tx_fifo_used,
165				       true, esp32s3_acm_put_char(port, ch),
166				       ({}));
167	if (pending) {
168		u32 int_ena;
169
170		int_ena = esp32s3_acm_read(port, USB_SERIAL_JTAG_INT_ENA_REG);
171		int_ena |= USB_SERIAL_JTAG_SERIAL_IN_EMPTY_INT_ENA;
172		esp32s3_acm_write(port, USB_SERIAL_JTAG_INT_ENA_REG, int_ena);
173	}
174	esp32s3_acm_push(port);
175}
176
177static void esp32s3_acm_txint(struct uart_port *port)
178{
179	esp32s3_acm_transmit_buffer(port);
180}
181
182static irqreturn_t esp32s3_acm_int(int irq, void *dev_id)
183{
184	struct uart_port *port = dev_id;
185	u32 status;
186
187	status = esp32s3_acm_read(port, USB_SERIAL_JTAG_INT_ST_REG);
188	esp32s3_acm_write(port, USB_SERIAL_JTAG_INT_CLR_REG, status);
189
190	if (status & USB_SERIAL_JTAG_SERIAL_OUT_RECV_PKT_INT_ST)
191		esp32s3_acm_rxint(port);
192	if (status & USB_SERIAL_JTAG_SERIAL_IN_EMPTY_INT_ST)
193		esp32s3_acm_txint(port);
194
195	return IRQ_RETVAL(status);
196}
197
198static void esp32s3_acm_start_tx(struct uart_port *port)
199{
200	esp32s3_acm_transmit_buffer(port);
201}
202
203static void esp32s3_acm_stop_rx(struct uart_port *port)
204{
205	u32 int_ena;
206
207	int_ena = esp32s3_acm_read(port, USB_SERIAL_JTAG_INT_ENA_REG);
208	int_ena &= ~USB_SERIAL_JTAG_SERIAL_OUT_RECV_PKT_INT_ENA;
209	esp32s3_acm_write(port, USB_SERIAL_JTAG_INT_ENA_REG, int_ena);
210}
211
212static int esp32s3_acm_startup(struct uart_port *port)
213{
214	int ret;
215
216	ret = request_irq(port->irq, esp32s3_acm_int, 0, DRIVER_NAME, port);
217	if (ret)
218		return ret;
219	esp32s3_acm_write(port, USB_SERIAL_JTAG_INT_ENA_REG,
220			  USB_SERIAL_JTAG_SERIAL_OUT_RECV_PKT_INT_ENA);
221
222	return 0;
223}
224
225static void esp32s3_acm_shutdown(struct uart_port *port)
226{
227	esp32s3_acm_write(port, USB_SERIAL_JTAG_INT_ENA_REG, 0);
228	free_irq(port->irq, port);
229}
230
231static void esp32s3_acm_set_termios(struct uart_port *port,
232				    struct ktermios *termios,
233				    const struct ktermios *old)
234{
235}
236
237static const char *esp32s3_acm_type(struct uart_port *port)
238{
239	return "ESP32S3 ACM";
240}
241
242/* configure/auto-configure the port */
243static void esp32s3_acm_config_port(struct uart_port *port, int flags)
244{
245	if (flags & UART_CONFIG_TYPE)
246		port->type = PORT_GENERIC;
247}
248
249#ifdef CONFIG_CONSOLE_POLL
250static void esp32s3_acm_poll_put_char(struct uart_port *port, unsigned char c)
251{
252	esp32s3_acm_put_char_sync(port, c);
253}
254
255static int esp32s3_acm_poll_get_char(struct uart_port *port)
256{
257	if (esp32s3_acm_rx_fifo_cnt(port))
258		return esp32s3_acm_read(port, USB_SERIAL_JTAG_EP1_REG);
259	else
260		return NO_POLL_CHAR;
261}
262#endif
263
264static const struct uart_ops esp32s3_acm_pops = {
265	.tx_empty	= esp32s3_acm_tx_empty,
266	.set_mctrl	= esp32s3_acm_set_mctrl,
267	.get_mctrl	= esp32s3_acm_get_mctrl,
268	.stop_tx	= esp32s3_acm_stop_tx,
269	.start_tx	= esp32s3_acm_start_tx,
270	.stop_rx	= esp32s3_acm_stop_rx,
271	.startup	= esp32s3_acm_startup,
272	.shutdown	= esp32s3_acm_shutdown,
273	.set_termios	= esp32s3_acm_set_termios,
274	.type		= esp32s3_acm_type,
275	.config_port	= esp32s3_acm_config_port,
276#ifdef CONFIG_CONSOLE_POLL
277	.poll_put_char	= esp32s3_acm_poll_put_char,
278	.poll_get_char	= esp32s3_acm_poll_get_char,
279#endif
280};
281
282static void esp32s3_acm_string_write(struct uart_port *port, const char *s,
283				     unsigned int count)
284{
285	uart_console_write(port, s, count, esp32s3_acm_put_char_sync);
286}
287
288static void
289esp32s3_acm_console_write(struct console *co, const char *s, unsigned int count)
290{
291	struct uart_port *port = esp32s3_acm_ports[co->index];
292	unsigned long flags;
293	bool locked = true;
294
295	if (port->sysrq)
296		locked = false;
297	else if (oops_in_progress)
298		locked = spin_trylock_irqsave(&port->lock, flags);
299	else
300		spin_lock_irqsave(&port->lock, flags);
301
302	esp32s3_acm_string_write(port, s, count);
303
304	if (locked)
305		spin_unlock_irqrestore(&port->lock, flags);
306}
307
308static struct uart_driver esp32s3_acm_reg;
309static struct console esp32s3_acm_console = {
310	.name		= DEV_NAME,
311	.write		= esp32s3_acm_console_write,
312	.device		= uart_console_device,
313	.flags		= CON_PRINTBUFFER,
314	.index		= -1,
315	.data		= &esp32s3_acm_reg,
316};
317
318static void esp32s3_acm_earlycon_write(struct console *con, const char *s,
319				      unsigned int n)
320{
321	struct earlycon_device *dev = con->data;
322
323	uart_console_write(&dev->port, s, n, esp32s3_acm_put_char_sync);
324}
325
326#ifdef CONFIG_CONSOLE_POLL
327static int esp32s3_acm_earlycon_read(struct console *con, char *s, unsigned int n)
328{
329	struct earlycon_device *dev = con->data;
330	unsigned int num_read = 0;
331
332	while (num_read < n) {
333		int c = esp32s3_acm_poll_get_char(&dev->port);
334
335		if (c == NO_POLL_CHAR)
336			break;
337		s[num_read++] = c;
338	}
339	return num_read;
340}
341#endif
342
343static int __init esp32s3_acm_early_console_setup(struct earlycon_device *device,
344						   const char *options)
345{
346	if (!device->port.membase)
347		return -ENODEV;
348
349	device->con->write = esp32s3_acm_earlycon_write;
350#ifdef CONFIG_CONSOLE_POLL
351	device->con->read = esp32s3_acm_earlycon_read;
352#endif
353	return 0;
354}
355
356OF_EARLYCON_DECLARE(esp32s3acm, "esp,esp32s3-acm",
357		    esp32s3_acm_early_console_setup);
358
359static struct uart_driver esp32s3_acm_reg = {
360	.owner		= THIS_MODULE,
361	.driver_name	= DRIVER_NAME,
362	.dev_name	= DEV_NAME,
363	.nr		= ARRAY_SIZE(esp32s3_acm_ports),
364	.cons		= &esp32s3_acm_console,
365};
366
367static int esp32s3_acm_probe(struct platform_device *pdev)
368{
369	struct device_node *np = pdev->dev.of_node;
370	struct uart_port *port;
371	struct resource *res;
372	int ret;
373
374	port = devm_kzalloc(&pdev->dev, sizeof(*port), GFP_KERNEL);
375	if (!port)
376		return -ENOMEM;
377
378	ret = of_alias_get_id(np, "serial");
379	if (ret < 0) {
380		dev_err(&pdev->dev, "failed to get alias id, errno %d\n", ret);
381		return ret;
382	}
383	if (ret >= UART_NR) {
384		dev_err(&pdev->dev, "driver limited to %d serial ports\n",
385			UART_NR);
386		return -ENOMEM;
387	}
388
389	port->line = ret;
390
391	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
392	if (!res)
393		return -ENODEV;
394
395	port->mapbase = res->start;
396	port->membase = devm_ioremap_resource(&pdev->dev, res);
397	if (IS_ERR(port->membase))
398		return PTR_ERR(port->membase);
399
400	port->dev = &pdev->dev;
401	port->type = PORT_GENERIC;
402	port->iotype = UPIO_MEM;
403	port->irq = platform_get_irq(pdev, 0);
404	port->ops = &esp32s3_acm_pops;
405	port->flags = UPF_BOOT_AUTOCONF;
406	port->has_sysrq = 1;
407	port->fifosize = ESP32S3_ACM_TX_FIFO_SIZE;
408
409	esp32s3_acm_ports[port->line] = port;
410
411	platform_set_drvdata(pdev, port);
412
413	return uart_add_one_port(&esp32s3_acm_reg, port);
414}
415
416static void esp32s3_acm_remove(struct platform_device *pdev)
417{
418	struct uart_port *port = platform_get_drvdata(pdev);
419
420	uart_remove_one_port(&esp32s3_acm_reg, port);
421}
422
423
424static struct platform_driver esp32s3_acm_driver = {
425	.probe		= esp32s3_acm_probe,
426	.remove_new	= esp32s3_acm_remove,
427	.driver		= {
428		.name	= DRIVER_NAME,
429		.of_match_table	= esp32s3_acm_dt_ids,
430	},
431};
432
433static int __init esp32s3_acm_init(void)
434{
435	int ret;
436
437	ret = uart_register_driver(&esp32s3_acm_reg);
438	if (ret)
439		return ret;
440
441	ret = platform_driver_register(&esp32s3_acm_driver);
442	if (ret)
443		uart_unregister_driver(&esp32s3_acm_reg);
444
445	return ret;
446}
447
448static void __exit esp32s3_acm_exit(void)
449{
450	platform_driver_unregister(&esp32s3_acm_driver);
451	uart_unregister_driver(&esp32s3_acm_reg);
452}
453
454module_init(esp32s3_acm_init);
455module_exit(esp32s3_acm_exit);
456
457MODULE_AUTHOR("Max Filippov <jcmvbkbc@gmail.com>");
458MODULE_LICENSE("GPL");
459