1 files changed, 501 insertions, 0 deletions
diff --git a/drivers/greybus/gb-beagleplay.c b/drivers/greybus/gb-beagleplay.c
new file mode 100644
index 000000000000..43318c1993ba
--- /dev/null
+++ b/drivers/greybus/gb-beagleplay.c
@@ -0,0 +1,501 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Beagleplay Linux Driver for Greybus
+ *
+ * Copyright (c) 2023 Ayush Singh <ayushdevel1325@gmail.com>
+ * Copyright (c) 2023 BeagleBoard.org Foundation
+ */
+
+#include <linux/gfp.h>
+#include <linux/greybus.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/printk.h>
+#include <linux/serdev.h>
+#include <linux/tty.h>
+#include <linux/tty_driver.h>
+#include <linux/greybus/hd.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/crc-ccitt.h>
+#include <linux/circ_buf.h>
+#include <linux/types.h>
+#include <linux/workqueue.h>
+
+#define RX_HDLC_PAYLOAD 256
+#define CRC_LEN 2
+#define MAX_RX_HDLC (1 + RX_HDLC_PAYLOAD + CRC_LEN)
+#define TX_CIRC_BUF_SIZE 1024
+
+#define ADDRESS_GREYBUS 0x01
+#define ADDRESS_DBG 0x02
+#define ADDRESS_CONTROL 0x03
+
+#define HDLC_FRAME 0x7E
+#define HDLC_ESC 0x7D
+#define HDLC_XOR 0x20
+
+#define CONTROL_SVC_START 0x01
+#define CONTROL_SVC_STOP 0x02
+
+/* The maximum number of CPorts supported by Greybus Host Device */
+#define GB_MAX_CPORTS 32
+
+/**
+ * struct gb_beagleplay - BeaglePlay Greybus driver
+ *
+ * @sd: underlying serdev device
+ *
+ * @gb_hd: greybus host device
+ *
+ * @tx_work: hdlc transmit work
+ * @tx_producer_lock: hdlc transmit data producer lock. acquired when appending data to buffer.
+ * @tx_consumer_lock: hdlc transmit data consumer lock. acquired when sending data over uart.
+ * @tx_circ_buf: hdlc transmit circular buffer.
+ * @tx_crc: hdlc transmit crc-ccitt fcs
+ *
+ * @rx_buffer_len: length of receive buffer filled.
+ * @rx_buffer: hdlc frame receive buffer
+ * @rx_in_esc: hdlc rx flag to indicate ESC frame
+ */
+struct gb_beagleplay {
+	struct serdev_device *sd;
+
+	struct gb_host_device *gb_hd;
+
+	struct work_struct tx_work;
+	spinlock_t tx_producer_lock;
+	spinlock_t tx_consumer_lock;
+	struct circ_buf tx_circ_buf;
+	u16 tx_crc;
+
+	u16 rx_buffer_len;
+	bool rx_in_esc;
+	u8 rx_buffer[MAX_RX_HDLC];
+};
+
+/**
+ * struct hdlc_payload - Structure to represent part of HDCL frame payload data.
+ *
+ * @len: buffer length in bytes
+ * @buf: payload buffer
+ */
+struct hdlc_payload {
+	u16 len;
+	void *buf;
+};
+
+static void hdlc_rx_greybus_frame(struct gb_beagleplay *bg, u8 *buf, u16 len)
+{
+	u16 cport_id;
+	struct gb_operation_msg_hdr *hdr = (struct gb_operation_msg_hdr *)buf;
+
+	memcpy(&cport_id, hdr->pad, sizeof(cport_id));
+
+	dev_dbg(&bg->sd->dev, "Greybus Operation %u type %X cport %u status %u received",
+		hdr->operation_id, hdr->type, cport_id, hdr->result);
+
+	greybus_data_rcvd(bg->gb_hd, cport_id, buf, len);
+}
+
+static void hdlc_rx_dbg_frame(const struct gb_beagleplay *bg, const char *buf, u16 len)
+{
+	dev_dbg(&bg->sd->dev, "CC1352 Log: %.*s", (int)len, buf);
+}
+
+/**
+ * hdlc_write() - Consume HDLC Buffer.
+ * @bg: beagleplay greybus driver
+ *
+ * Assumes that consumer lock has been acquired.
+ */
+static void hdlc_write(struct gb_beagleplay *bg)
+{
+	int written;
+	/* Start consuming HDLC data */
+	int head = smp_load_acquire(&bg->tx_circ_buf.head);
+	int tail = bg->tx_circ_buf.tail;
+	int count = CIRC_CNT_TO_END(head, tail, TX_CIRC_BUF_SIZE);
+	const unsigned char *buf = &bg->tx_circ_buf.buf[tail];
+
+	if (count > 0) {
+		written = serdev_device_write_buf(bg->sd, buf, count);
+
+		/* Finish consuming HDLC data */
+		smp_store_release(&bg->tx_circ_buf.tail, (tail + written) & (TX_CIRC_BUF_SIZE - 1));
+	}
+}
+
+/**
+ * hdlc_append() - Queue HDLC data for sending.
+ * @bg: beagleplay greybus driver
+ * @value: hdlc byte to transmit
+ *
+ * Assumes that producer lock as been acquired.
+ */
+static void hdlc_append(struct gb_beagleplay *bg, u8 value)
+{
+	int tail, head = bg->tx_circ_buf.head;
+
+	while (true) {
+		tail = READ_ONCE(bg->tx_circ_buf.tail);
+
+		if (CIRC_SPACE(head, tail, TX_CIRC_BUF_SIZE) >= 1) {
+			bg->tx_circ_buf.buf[head] = value;
+
+			/* Finish producing HDLC byte */
+			smp_store_release(&bg->tx_circ_buf.head,
+					  (head + 1) & (TX_CIRC_BUF_SIZE - 1));
+			return;
+		}
+		dev_warn(&bg->sd->dev, "Tx circ buf full");
+		usleep_range(3000, 5000);
+	}
+}
+
+static void hdlc_append_escaped(struct gb_beagleplay *bg, u8 value)
+{
+	if (value == HDLC_FRAME || value == HDLC_ESC) {
+		hdlc_append(bg, HDLC_ESC);
+		value ^= HDLC_XOR;
+	}
+	hdlc_append(bg, value);
+}
+
+static void hdlc_append_tx_frame(struct gb_beagleplay *bg)
+{
+	bg->tx_crc = 0xFFFF;
+	hdlc_append(bg, HDLC_FRAME);
+}
+
+static void hdlc_append_tx_u8(struct gb_beagleplay *bg, u8 value)
+{
+	bg->tx_crc = crc_ccitt(bg->tx_crc, &value, 1);
+	hdlc_append_escaped(bg, value);
+}
+
+static void hdlc_append_tx_buf(struct gb_beagleplay *bg, const u8 *buf, u16 len)
+{
+	size_t i;
+
+	for (i = 0; i < len; i++)
+		hdlc_append_tx_u8(bg, buf[i]);
+}
+
+static void hdlc_append_tx_crc(struct gb_beagleplay *bg)
+{
+	bg->tx_crc ^= 0xffff;
+	hdlc_append_escaped(bg, bg->tx_crc & 0xff);
+	hdlc_append_escaped(bg, (bg->tx_crc >> 8) & 0xff);
+}
+
+static void hdlc_transmit(struct work_struct *work)
+{
+	struct gb_beagleplay *bg = container_of(work, struct gb_beagleplay, tx_work);
+
+	spin_lock_bh(&bg->tx_consumer_lock);
+	hdlc_write(bg);
+	spin_unlock_bh(&bg->tx_consumer_lock);
+}
+
+static void hdlc_tx_frames(struct gb_beagleplay *bg, u8 address, u8 control,
+			   const struct hdlc_payload payloads[], size_t count)
+{
+	size_t i;
+
+	spin_lock(&bg->tx_producer_lock);
+
+	hdlc_append_tx_frame(bg);
+	hdlc_append_tx_u8(bg, address);
+	hdlc_append_tx_u8(bg, control);
+
+	for (i = 0; i < count; ++i)
+		hdlc_append_tx_buf(bg, payloads[i].buf, payloads[i].len);
+
+	hdlc_append_tx_crc(bg);
+	hdlc_append_tx_frame(bg);
+
+	spin_unlock(&bg->tx_producer_lock);
+
+	schedule_work(&bg->tx_work);
+}
+
+static void hdlc_tx_s_frame_ack(struct gb_beagleplay *bg)
+{
+	hdlc_tx_frames(bg, bg->rx_buffer[0], (bg->rx_buffer[1] >> 1) & 0x7, NULL, 0);
+}
+
+static void hdlc_rx_frame(struct gb_beagleplay *bg)
+{
+	u16 crc, len;
+	u8 ctrl, *buf;
+	u8 address = bg->rx_buffer[0];
+
+	crc = crc_ccitt(0xffff, bg->rx_buffer, bg->rx_buffer_len);
+	if (crc != 0xf0b8) {
+		dev_warn_ratelimited(&bg->sd->dev, "CRC failed from %02x: 0x%04x", address, crc);
+		return;
+	}
+
+	ctrl = bg->rx_buffer[1];
+	buf = &bg->rx_buffer[2];
+	len = bg->rx_buffer_len - 4;
+
+	/* I-Frame, send S-Frame ACK */
+	if ((ctrl & 1) == 0)
+		hdlc_tx_s_frame_ack(bg);
+
+	switch (address) {
+	case ADDRESS_DBG:
+		hdlc_rx_dbg_frame(bg, buf, len);
+		break;
+	case ADDRESS_GREYBUS:
+		hdlc_rx_greybus_frame(bg, buf, len);
+		break;
+	default:
+		dev_warn_ratelimited(&bg->sd->dev, "unknown frame %u", address);
+	}
+}
+
+static int hdlc_rx(struct gb_beagleplay *bg, const u8 *data, size_t count)
+{
+	size_t i;
+	u8 c;
+
+	for (i = 0; i < count; ++i) {
+		c = data[i];
+
+		switch (c) {
+		case HDLC_FRAME:
+			if (bg->rx_buffer_len)
+				hdlc_rx_frame(bg);
+
+			bg->rx_buffer_len = 0;
+			break;
+		case HDLC_ESC:
+			bg->rx_in_esc = true;
+			break;
+		default:
+			if (bg->rx_in_esc) {
+				c ^= 0x20;
+				bg->rx_in_esc = false;
+			}
+
+			if (bg->rx_buffer_len < MAX_RX_HDLC) {
+				bg->rx_buffer[bg->rx_buffer_len] = c;
+				bg->rx_buffer_len++;
+			} else {
+				dev_err_ratelimited(&bg->sd->dev, "RX Buffer Overflow");
+				bg->rx_buffer_len = 0;
+			}
+		}
+	}
+
+	return count;
+}
+
+static int hdlc_init(struct gb_beagleplay *bg)
+{
+	INIT_WORK(&bg->tx_work, hdlc_transmit);
+	spin_lock_init(&bg->tx_producer_lock);
+	spin_lock_init(&bg->tx_consumer_lock);
+	bg->tx_circ_buf.head = 0;
+	bg->tx_circ_buf.tail = 0;
+
+	bg->tx_circ_buf.buf = devm_kmalloc(&bg->sd->dev, TX_CIRC_BUF_SIZE, GFP_KERNEL);
+	if (!bg->tx_circ_buf.buf)
+		return -ENOMEM;
+
+	bg->rx_buffer_len = 0;
+	bg->rx_in_esc = false;
+
+	return 0;
+}
+
+static void hdlc_deinit(struct gb_beagleplay *bg)
+{
+	flush_work(&bg->tx_work);
+}
+
+static int gb_tty_receive(struct serdev_device *sd, const unsigned char *data, size_t count)
+{
+	struct gb_beagleplay *bg = serdev_device_get_drvdata(sd);
+
+	return hdlc_rx(bg, data, count);
+}
+
+static void gb_tty_wakeup(struct serdev_device *serdev)
+{
+	struct gb_beagleplay *bg = serdev_device_get_drvdata(serdev);
+
+	schedule_work(&bg->tx_work);
+}
+
+static struct serdev_device_ops gb_beagleplay_ops = {
+	.receive_buf = gb_tty_receive,
+	.write_wakeup = gb_tty_wakeup,
+};
+
+static int gb_message_send(struct gb_host_device *hd, u16 cport, struct gb_message *msg, gfp_t mask)
+{
+	struct gb_beagleplay *bg = dev_get_drvdata(&hd->dev);
+	struct hdlc_payload payloads[2];
+
+	dev_dbg(&hd->dev, "Sending greybus message with Operation %u, Type: %X on Cport %u",
+		msg->header->operation_id, msg->header->type, cport);
+
+	if (msg->header->size > RX_HDLC_PAYLOAD)
+		return dev_err_probe(&hd->dev, -E2BIG, "Greybus message too big");
+
+	memcpy(msg->header->pad, &cport, sizeof(cport));
+
+	payloads[0].buf = msg->header;
+	payloads[0].len = sizeof(*msg->header);
+	payloads[1].buf = msg->payload;
+	payloads[1].len = msg->payload_size;
+
+	hdlc_tx_frames(bg, ADDRESS_GREYBUS, 0x03, payloads, 2);
+	greybus_message_sent(bg->gb_hd, msg, 0);
+
+	return 0;
+}
+
+static void gb_message_cancel(struct gb_message *message)
+{
+}
+
+static struct gb_hd_driver gb_hdlc_driver = { .message_send = gb_message_send,
+					      .message_cancel = gb_message_cancel };
+
+static void gb_beagleplay_start_svc(struct gb_beagleplay *bg)
+{
+	const u8 command = CONTROL_SVC_START;
+	const struct hdlc_payload payload = { .len = 1, .buf = (void *)&command };
+
+	hdlc_tx_frames(bg, ADDRESS_CONTROL, 0x03, &payload, 1);
+}
+
+static void gb_beagleplay_stop_svc(struct gb_beagleplay *bg)
+{
+	const u8 command = CONTROL_SVC_STOP;
+	const struct hdlc_payload payload = { .len = 1, .buf = (void *)&command };
+
+	hdlc_tx_frames(bg, ADDRESS_CONTROL, 0x03, &payload, 1);
+}
+
+static void gb_greybus_deinit(struct gb_beagleplay *bg)
+{
+	gb_hd_del(bg->gb_hd);
+	gb_hd_put(bg->gb_hd);
+}
+
+static int gb_greybus_init(struct gb_beagleplay *bg)
+{
+	int ret;
+
+	bg->gb_hd = gb_hd_create(&gb_hdlc_driver, &bg->sd->dev, TX_CIRC_BUF_SIZE, GB_MAX_CPORTS);
+	if (IS_ERR(bg->gb_hd)) {
+		dev_err(&bg->sd->dev, "Failed to create greybus host device");
+		return PTR_ERR(bg->gb_hd);
+	}
+
+	ret = gb_hd_add(bg->gb_hd);
+	if (ret) {
+		dev_err(&bg->sd->dev, "Failed to add greybus host device");
+		goto free_gb_hd;
+	}
+	dev_set_drvdata(&bg->gb_hd->dev, bg);
+
+	return 0;
+
+free_gb_hd:
+	gb_greybus_deinit(bg);
+	return ret;
+}
+
+static void gb_serdev_deinit(struct gb_beagleplay *bg)
+{
+	serdev_device_close(bg->sd);
+}
+
+static int gb_serdev_init(struct gb_beagleplay *bg)
+{
+	int ret;
+
+	serdev_device_set_drvdata(bg->sd, bg);
+	serdev_device_set_client_ops(bg->sd, &gb_beagleplay_ops);
+	ret = serdev_device_open(bg->sd);
+	if (ret)
+		return dev_err_probe(&bg->sd->dev, ret, "Unable to open serial device");
+
+	serdev_device_set_baudrate(bg->sd, 115200);
+	serdev_device_set_flow_control(bg->sd, false);
+
+	return 0;
+}
+
+static int gb_beagleplay_probe(struct serdev_device *serdev)
+{
+	int ret = 0;
+	struct gb_beagleplay *bg;
+
+	bg = devm_kmalloc(&serdev->dev, sizeof(*bg), GFP_KERNEL);
+	if (!bg)
+		return -ENOMEM;
+
+	bg->sd = serdev;
+	ret = gb_serdev_init(bg);
+	if (ret)
+		return ret;
+
+	ret = hdlc_init(bg);
+	if (ret)
+		goto free_serdev;
+
+	ret = gb_greybus_init(bg);
+	if (ret)
+		goto free_hdlc;
+
+	gb_beagleplay_start_svc(bg);
+
+	return 0;
+
+free_hdlc:
+	hdlc_deinit(bg);
+free_serdev:
+	gb_serdev_deinit(bg);
+	return ret;
+}
+
+static void gb_beagleplay_remove(struct serdev_device *serdev)
+{
+	struct gb_beagleplay *bg = serdev_device_get_drvdata(serdev);
+
+	gb_greybus_deinit(bg);
+	gb_beagleplay_stop_svc(bg);
+	hdlc_deinit(bg);
+	gb_serdev_deinit(bg);
+}
+
+static const struct of_device_id gb_beagleplay_of_match[] = {
+	{
+		.compatible = "ti,cc1352p7",
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, gb_beagleplay_of_match);
+
+static struct serdev_device_driver gb_beagleplay_driver = {
+	.probe = gb_beagleplay_probe,
+	.remove = gb_beagleplay_remove,
+	.driver = {
+		.name = "gb_beagleplay",
+		.of_match_table = gb_beagleplay_of_match,
+	},
+};
+
+module_serdev_device_driver(gb_beagleplay_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Ayush Singh <ayushdevel1325@gmail.com>");
+MODULE_DESCRIPTION("A Greybus driver for BeaglePlay");