xref: /linux/drivers/tty/serial/esp32_acm.c (revision fc67d663aabdfddbba8e16a40c3f6a973face509) 
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  
39  static const struct of_device_id esp32s3_acm_dt_ids[] = {
40  	{
41  		.compatible = "esp,esp32s3-acm",
42  	}, { /* sentinel */ }
43  };
44  MODULE_DEVICE_TABLE(of, esp32s3_acm_dt_ids);
45  
46  static struct uart_port *esp32s3_acm_ports[UART_NR];
47  
48  static void esp32s3_acm_write(struct uart_port *port, unsigned long reg, u32 v)
49  {
50  	writel(v, port->membase + reg);
51  }
52  
53  static u32 esp32s3_acm_read(struct uart_port *port, unsigned long reg)
54  {
55  	return readl(port->membase + reg);
56  }
57  
58  static 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  
65  static 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  
72  static 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 */
80  static 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  
85  static void esp32s3_acm_set_mctrl(struct uart_port *port, unsigned int mctrl)
86  {
87  }
88  
89  static unsigned int esp32s3_acm_get_mctrl(struct uart_port *port)
90  {
91  	return TIOCM_CAR;
92  }
93  
94  static 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  
103  static 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  
126  static 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  
133  static 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  
138  static 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  
153  static 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  
177  static void esp32s3_acm_txint(struct uart_port *port)
178  {
179  	esp32s3_acm_transmit_buffer(port);
180  }
181  
182  static 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  
198  static void esp32s3_acm_start_tx(struct uart_port *port)
199  {
200  	esp32s3_acm_transmit_buffer(port);
201  }
202  
203  static 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  
212  static 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  
225  static 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  
231  static void esp32s3_acm_set_termios(struct uart_port *port,
232  				    struct ktermios *termios,
233  				    const struct ktermios *old)
234  {
235  }
236  
237  static const char *esp32s3_acm_type(struct uart_port *port)
238  {
239  	return "ESP32S3 ACM";
240  }
241  
242  /* configure/auto-configure the port */
243  static 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
250  static void esp32s3_acm_poll_put_char(struct uart_port *port, unsigned char c)
251  {
252  	esp32s3_acm_put_char_sync(port, c);
253  }
254  
255  static 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  
264  static 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  
282  static 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  
288  static void
289  esp32s3_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  
308  static struct uart_driver esp32s3_acm_reg;
309  static 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  
318  static 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
327  static 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  
343  static 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  
356  OF_EARLYCON_DECLARE(esp32s3acm, "esp,esp32s3-acm",
357  		    esp32s3_acm_early_console_setup);
358  
359  static 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  
367  static 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  
416  static 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  
424  static 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  
433  static 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  
448  static void __exit esp32s3_acm_exit(void)
449  {
450  	platform_driver_unregister(&esp32s3_acm_driver);
451  	uart_unregister_driver(&esp32s3_acm_reg);
452  }
453  
454  module_init(esp32s3_acm_init);
455  module_exit(esp32s3_acm_exit);
456  
457  MODULE_AUTHOR("Max Filippov <jcmvbkbc@gmail.com>");
458  MODULE_LICENSE("GPL");
459