1 // SPDX-License-Identifier: GPL-2.0
3 * Beagleplay Linux Driver for Greybus
5 * Copyright (c) 2023 Ayush Singh <ayushdevel1325@gmail.com>
6 * Copyright (c) 2023 BeagleBoard.org Foundation
10 #include <linux/greybus.h>
11 #include <linux/module.h>
13 #include <linux/printk.h>
14 #include <linux/serdev.h>
15 #include <linux/tty.h>
16 #include <linux/tty_driver.h>
17 #include <linux/greybus/hd.h>
18 #include <linux/init.h>
19 #include <linux/device.h>
20 #include <linux/crc-ccitt.h>
21 #include <linux/circ_buf.h>
22 #include <linux/types.h>
23 #include <linux/workqueue.h>
25 #define RX_HDLC_PAYLOAD 256
27 #define MAX_RX_HDLC (1 + RX_HDLC_PAYLOAD + CRC_LEN)
28 #define TX_CIRC_BUF_SIZE 1024
30 #define ADDRESS_GREYBUS 0x01
31 #define ADDRESS_DBG 0x02
32 #define ADDRESS_CONTROL 0x03
34 #define HDLC_FRAME 0x7E
38 #define CONTROL_SVC_START 0x01
39 #define CONTROL_SVC_STOP 0x02
41 /* The maximum number of CPorts supported by Greybus Host Device */
42 #define GB_MAX_CPORTS 32
45 * struct gb_beagleplay - BeaglePlay Greybus driver
47 * @sd: underlying serdev device
49 * @gb_hd: greybus host device
51 * @tx_work: hdlc transmit work
52 * @tx_producer_lock: hdlc transmit data producer lock. acquired when appending data to buffer.
53 * @tx_consumer_lock: hdlc transmit data consumer lock. acquired when sending data over uart.
54 * @tx_circ_buf: hdlc transmit circular buffer.
55 * @tx_crc: hdlc transmit crc-ccitt fcs
57 * @rx_buffer_len: length of receive buffer filled.
58 * @rx_buffer: hdlc frame receive buffer
59 * @rx_in_esc: hdlc rx flag to indicate ESC frame
61 struct gb_beagleplay {
62 struct serdev_device *sd;
64 struct gb_host_device *gb_hd;
66 struct work_struct tx_work;
67 spinlock_t tx_producer_lock;
68 spinlock_t tx_consumer_lock;
69 struct circ_buf tx_circ_buf;
74 u8 rx_buffer[MAX_RX_HDLC];
78 * struct hdlc_payload - Structure to represent part of HDCL frame payload data.
80 * @len: buffer length in bytes
81 * @buf: payload buffer
89 * struct hdlc_greybus_frame - Structure to represent greybus HDLC frame payload
92 * @hdr: greybus operation header
93 * @payload: greybus message payload
95 * The HDLC payload sent over UART for greybus address has cport preappended to greybus message
97 struct hdlc_greybus_frame {
99 struct gb_operation_msg_hdr hdr;
103 static void hdlc_rx_greybus_frame(struct gb_beagleplay *bg, u8 *buf, u16 len)
105 struct hdlc_greybus_frame *gb_frame = (struct hdlc_greybus_frame *)buf;
106 u16 cport_id = le16_to_cpu(gb_frame->cport);
107 u16 gb_msg_len = le16_to_cpu(gb_frame->hdr.size);
109 dev_dbg(&bg->sd->dev, "Greybus Operation %u type %X cport %u status %u received",
110 gb_frame->hdr.operation_id, gb_frame->hdr.type, cport_id, gb_frame->hdr.result);
112 greybus_data_rcvd(bg->gb_hd, cport_id, (u8 *)&gb_frame->hdr, gb_msg_len);
115 static void hdlc_rx_dbg_frame(const struct gb_beagleplay *bg, const char *buf, u16 len)
117 dev_dbg(&bg->sd->dev, "CC1352 Log: %.*s", (int)len, buf);
121 * hdlc_write() - Consume HDLC Buffer.
122 * @bg: beagleplay greybus driver
124 * Assumes that consumer lock has been acquired.
126 static void hdlc_write(struct gb_beagleplay *bg)
129 /* Start consuming HDLC data */
130 int head = smp_load_acquire(&bg->tx_circ_buf.head);
131 int tail = bg->tx_circ_buf.tail;
132 int count = CIRC_CNT_TO_END(head, tail, TX_CIRC_BUF_SIZE);
133 const unsigned char *buf = &bg->tx_circ_buf.buf[tail];
136 written = serdev_device_write_buf(bg->sd, buf, count);
138 /* Finish consuming HDLC data */
139 smp_store_release(&bg->tx_circ_buf.tail, (tail + written) & (TX_CIRC_BUF_SIZE - 1));
144 * hdlc_append() - Queue HDLC data for sending.
145 * @bg: beagleplay greybus driver
146 * @value: hdlc byte to transmit
148 * Assumes that producer lock as been acquired.
150 static void hdlc_append(struct gb_beagleplay *bg, u8 value)
152 int tail, head = bg->tx_circ_buf.head;
155 tail = READ_ONCE(bg->tx_circ_buf.tail);
157 if (CIRC_SPACE(head, tail, TX_CIRC_BUF_SIZE) >= 1) {
158 bg->tx_circ_buf.buf[head] = value;
160 /* Finish producing HDLC byte */
161 smp_store_release(&bg->tx_circ_buf.head,
162 (head + 1) & (TX_CIRC_BUF_SIZE - 1));
165 dev_warn(&bg->sd->dev, "Tx circ buf full");
166 usleep_range(3000, 5000);
170 static void hdlc_append_escaped(struct gb_beagleplay *bg, u8 value)
172 if (value == HDLC_FRAME || value == HDLC_ESC) {
173 hdlc_append(bg, HDLC_ESC);
176 hdlc_append(bg, value);
179 static void hdlc_append_tx_frame(struct gb_beagleplay *bg)
182 hdlc_append(bg, HDLC_FRAME);
185 static void hdlc_append_tx_u8(struct gb_beagleplay *bg, u8 value)
187 bg->tx_crc = crc_ccitt(bg->tx_crc, &value, 1);
188 hdlc_append_escaped(bg, value);
191 static void hdlc_append_tx_buf(struct gb_beagleplay *bg, const u8 *buf, u16 len)
195 for (i = 0; i < len; i++)
196 hdlc_append_tx_u8(bg, buf[i]);
199 static void hdlc_append_tx_crc(struct gb_beagleplay *bg)
201 bg->tx_crc ^= 0xffff;
202 hdlc_append_escaped(bg, bg->tx_crc & 0xff);
203 hdlc_append_escaped(bg, (bg->tx_crc >> 8) & 0xff);
206 static void hdlc_transmit(struct work_struct *work)
208 struct gb_beagleplay *bg = container_of(work, struct gb_beagleplay, tx_work);
210 spin_lock_bh(&bg->tx_consumer_lock);
212 spin_unlock_bh(&bg->tx_consumer_lock);
215 static void hdlc_tx_frames(struct gb_beagleplay *bg, u8 address, u8 control,
216 const struct hdlc_payload payloads[], size_t count)
220 spin_lock(&bg->tx_producer_lock);
222 hdlc_append_tx_frame(bg);
223 hdlc_append_tx_u8(bg, address);
224 hdlc_append_tx_u8(bg, control);
226 for (i = 0; i < count; ++i)
227 hdlc_append_tx_buf(bg, payloads[i].buf, payloads[i].len);
229 hdlc_append_tx_crc(bg);
230 hdlc_append_tx_frame(bg);
232 spin_unlock(&bg->tx_producer_lock);
234 schedule_work(&bg->tx_work);
237 static void hdlc_tx_s_frame_ack(struct gb_beagleplay *bg)
239 hdlc_tx_frames(bg, bg->rx_buffer[0], (bg->rx_buffer[1] >> 1) & 0x7, NULL, 0);
242 static void hdlc_rx_frame(struct gb_beagleplay *bg)
246 u8 address = bg->rx_buffer[0];
248 crc = crc_ccitt(0xffff, bg->rx_buffer, bg->rx_buffer_len);
250 dev_warn_ratelimited(&bg->sd->dev, "CRC failed from %02x: 0x%04x", address, crc);
254 ctrl = bg->rx_buffer[1];
255 buf = &bg->rx_buffer[2];
256 len = bg->rx_buffer_len - 4;
258 /* I-Frame, send S-Frame ACK */
260 hdlc_tx_s_frame_ack(bg);
264 hdlc_rx_dbg_frame(bg, buf, len);
266 case ADDRESS_GREYBUS:
267 hdlc_rx_greybus_frame(bg, buf, len);
270 dev_warn_ratelimited(&bg->sd->dev, "unknown frame %u", address);
274 static ssize_t hdlc_rx(struct gb_beagleplay *bg, const u8 *data, size_t count)
279 for (i = 0; i < count; ++i) {
284 if (bg->rx_buffer_len)
287 bg->rx_buffer_len = 0;
290 bg->rx_in_esc = true;
295 bg->rx_in_esc = false;
298 if (bg->rx_buffer_len < MAX_RX_HDLC) {
299 bg->rx_buffer[bg->rx_buffer_len] = c;
302 dev_err_ratelimited(&bg->sd->dev, "RX Buffer Overflow");
303 bg->rx_buffer_len = 0;
311 static int hdlc_init(struct gb_beagleplay *bg)
313 INIT_WORK(&bg->tx_work, hdlc_transmit);
314 spin_lock_init(&bg->tx_producer_lock);
315 spin_lock_init(&bg->tx_consumer_lock);
316 bg->tx_circ_buf.head = 0;
317 bg->tx_circ_buf.tail = 0;
319 bg->tx_circ_buf.buf = devm_kmalloc(&bg->sd->dev, TX_CIRC_BUF_SIZE, GFP_KERNEL);
320 if (!bg->tx_circ_buf.buf)
323 bg->rx_buffer_len = 0;
324 bg->rx_in_esc = false;
329 static void hdlc_deinit(struct gb_beagleplay *bg)
331 flush_work(&bg->tx_work);
334 static ssize_t gb_tty_receive(struct serdev_device *sd, const u8 *data,
337 struct gb_beagleplay *bg = serdev_device_get_drvdata(sd);
339 return hdlc_rx(bg, data, count);
342 static void gb_tty_wakeup(struct serdev_device *serdev)
344 struct gb_beagleplay *bg = serdev_device_get_drvdata(serdev);
346 schedule_work(&bg->tx_work);
349 static struct serdev_device_ops gb_beagleplay_ops = {
350 .receive_buf = gb_tty_receive,
351 .write_wakeup = gb_tty_wakeup,
355 * gb_message_send() - Send greybus message using HDLC over UART
357 * @hd: pointer to greybus host device
358 * @cport: AP cport where message originates
359 * @msg: greybus message to send
362 * Greybus HDLC frame has the following payload:
364 * 2. gb_operation_msg_hdr msg_header
367 static int gb_message_send(struct gb_host_device *hd, u16 cport, struct gb_message *msg, gfp_t mask)
369 struct gb_beagleplay *bg = dev_get_drvdata(&hd->dev);
370 struct hdlc_payload payloads[3];
371 __le16 cport_id = cpu_to_le16(cport);
373 dev_dbg(&hd->dev, "Sending greybus message with Operation %u, Type: %X on Cport %u",
374 msg->header->operation_id, msg->header->type, cport);
376 if (le16_to_cpu(msg->header->size) > RX_HDLC_PAYLOAD)
377 return dev_err_probe(&hd->dev, -E2BIG, "Greybus message too big");
379 payloads[0].buf = &cport_id;
380 payloads[0].len = sizeof(cport_id);
381 payloads[1].buf = msg->header;
382 payloads[1].len = sizeof(*msg->header);
383 payloads[2].buf = msg->payload;
384 payloads[2].len = msg->payload_size;
386 hdlc_tx_frames(bg, ADDRESS_GREYBUS, 0x03, payloads, 3);
387 greybus_message_sent(bg->gb_hd, msg, 0);
392 static void gb_message_cancel(struct gb_message *message)
396 static struct gb_hd_driver gb_hdlc_driver = { .message_send = gb_message_send,
397 .message_cancel = gb_message_cancel };
399 static void gb_beagleplay_start_svc(struct gb_beagleplay *bg)
401 const u8 command = CONTROL_SVC_START;
402 const struct hdlc_payload payload = { .len = 1, .buf = (void *)&command };
404 hdlc_tx_frames(bg, ADDRESS_CONTROL, 0x03, &payload, 1);
407 static void gb_beagleplay_stop_svc(struct gb_beagleplay *bg)
409 const u8 command = CONTROL_SVC_STOP;
410 const struct hdlc_payload payload = { .len = 1, .buf = (void *)&command };
412 hdlc_tx_frames(bg, ADDRESS_CONTROL, 0x03, &payload, 1);
415 static void gb_greybus_deinit(struct gb_beagleplay *bg)
417 gb_hd_del(bg->gb_hd);
418 gb_hd_put(bg->gb_hd);
421 static int gb_greybus_init(struct gb_beagleplay *bg)
425 bg->gb_hd = gb_hd_create(&gb_hdlc_driver, &bg->sd->dev, TX_CIRC_BUF_SIZE, GB_MAX_CPORTS);
426 if (IS_ERR(bg->gb_hd)) {
427 dev_err(&bg->sd->dev, "Failed to create greybus host device");
428 return PTR_ERR(bg->gb_hd);
431 ret = gb_hd_add(bg->gb_hd);
433 dev_err(&bg->sd->dev, "Failed to add greybus host device");
436 dev_set_drvdata(&bg->gb_hd->dev, bg);
441 gb_greybus_deinit(bg);
445 static void gb_serdev_deinit(struct gb_beagleplay *bg)
447 serdev_device_close(bg->sd);
450 static int gb_serdev_init(struct gb_beagleplay *bg)
454 serdev_device_set_drvdata(bg->sd, bg);
455 serdev_device_set_client_ops(bg->sd, &gb_beagleplay_ops);
456 ret = serdev_device_open(bg->sd);
458 return dev_err_probe(&bg->sd->dev, ret, "Unable to open serial device");
460 serdev_device_set_baudrate(bg->sd, 115200);
461 serdev_device_set_flow_control(bg->sd, false);
466 static int gb_beagleplay_probe(struct serdev_device *serdev)
469 struct gb_beagleplay *bg;
471 bg = devm_kmalloc(&serdev->dev, sizeof(*bg), GFP_KERNEL);
476 ret = gb_serdev_init(bg);
484 ret = gb_greybus_init(bg);
488 gb_beagleplay_start_svc(bg);
495 gb_serdev_deinit(bg);
499 static void gb_beagleplay_remove(struct serdev_device *serdev)
501 struct gb_beagleplay *bg = serdev_device_get_drvdata(serdev);
503 gb_greybus_deinit(bg);
504 gb_beagleplay_stop_svc(bg);
506 gb_serdev_deinit(bg);
509 static const struct of_device_id gb_beagleplay_of_match[] = {
511 .compatible = "ti,cc1352p7",
515 MODULE_DEVICE_TABLE(of, gb_beagleplay_of_match);
517 static struct serdev_device_driver gb_beagleplay_driver = {
518 .probe = gb_beagleplay_probe,
519 .remove = gb_beagleplay_remove,
521 .name = "gb_beagleplay",
522 .of_match_table = gb_beagleplay_of_match,
526 module_serdev_device_driver(gb_beagleplay_driver);
528 MODULE_LICENSE("GPL");
529 MODULE_AUTHOR("Ayush Singh <ayushdevel1325@gmail.com>");
530 MODULE_DESCRIPTION("A Greybus driver for BeaglePlay");