[RFC net-next 11/15] net: lora: Add IMST WiMOD

["Andreas Färber" <afaerber@suse.de>]

The IMST WiMOD uses a SLIP based binary UART protocol. Two separate
firmwares are available. By default it ships with a LoRaWAN firmware.
The alternative firmware is a custom P2P addressing mode based on LoRa.

Cc: Jon Ortego <Jon.Ortego@imst.de>
Signed-off-by: Andreas Färber <afaerber@suse.de>
---
 drivers/net/lora/Kconfig  |   8 +
 drivers/net/lora/Makefile |   3 +
 drivers/net/lora/wimod.c  | 597 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 608 insertions(+)
 create mode 100644 drivers/net/lora/wimod.c

diff --git a/drivers/net/lora/Kconfig b/drivers/net/lora/Kconfig
index 940bd2cbe106..2e05caef8645 100644
--- a/drivers/net/lora/Kconfig
+++ b/drivers/net/lora/Kconfig
@@ -31,6 +31,14 @@ config LORA_SX1276
 	help
 	  Semtech SX1272/1276/1278
 
+config LORA_WIMOD
+	tristate "IMST WiMOD driver"
+	default y
+	depends on SERIAL_DEV_BUS
+	select CRC_CCITT
+	help
+	  IMST WiMOD
+
 endif
 
 endmenu
diff --git a/drivers/net/lora/Makefile b/drivers/net/lora/Makefile
index 07839c3ce9f8..ecb326c859a5 100644
--- a/drivers/net/lora/Makefile
+++ b/drivers/net/lora/Makefile
@@ -15,3 +15,6 @@ lora-rn2483-y += rn2483_cmd.o
 
 obj-$(CONFIG_LORA_SX1276) += lora-sx1276.o
 lora-sx1276-y := sx1276.o
+
+obj-$(CONFIG_LORA_WIMOD) += lora-wimod.o
+lora-wimod-y := wimod.o
diff --git a/drivers/net/lora/wimod.c b/drivers/net/lora/wimod.c
new file mode 100644
index 000000000000..a70d5a6dc7c4
--- /dev/null
+++ b/drivers/net/lora/wimod.c
@@ -0,0 +1,597 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * IMST WiMOD
+ *
+ * Copyright (c) 2017-2018 Andreas Färber
+ */
+
+#include <linux/crc-ccitt.h>
+#include <linux/lora.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/of.h>
+#include <linux/rculist.h>
+#include <linux/serdev.h>
+
+#define WIMOD_HCI_PAYLOAD_MAX	300
+#define WIMOD_HCI_PACKET_MAX	(1 + (2 + WIMOD_HCI_PAYLOAD_MAX + 2) * 2 + 1)
+
+struct wimod_device {
+	struct serdev_device *serdev;
+
+	u8 rx_buf[WIMOD_HCI_PACKET_MAX];
+	int rx_len;
+	bool rx_esc;
+	struct list_head packet_dispatchers;
+};
+
+#define SLIP_END	0300
+#define SLIP_ESC	0333
+#define SLIP_ESC_END	0334
+#define SLIP_ESC_ESC	0335
+
+static inline void slip_print_bytes(const u8* buf, int len)
+{
+	int i;
+
+	for (i = 0; i < len; i++)
+		printk("%02x ", buf[i]);
+}
+
+static int slip_send_end(struct serdev_device *sdev, unsigned long timeout)
+{
+	u8 val = SLIP_END;
+
+	return serdev_device_write(sdev, &val, 1, timeout);
+}
+
+#if 0
+static int slip_send_data(struct serdev_device *sdev, const u8 *buf, int len,
+	unsigned long timeout)
+{
+	int last_idx = -1;
+	int i;
+	u8 esc[2] = { SLIP_ESC, 0 };
+	int ret;
+
+	for (i = 0; i < len; i++) {
+		if (buf[i] != SLIP_END &&
+		    buf[i] != SLIP_ESC)
+			continue;
+
+		slip_print_bytes(&buf[last_idx + 1], i - (last_idx + 1));
+
+		ret = serdev_device_write(sdev,
+			&buf[last_idx + 1], i - (last_idx + 1), timeout);
+		if (ret)
+			return ret;
+
+		switch (buf[i]) {
+		case SLIP_END:
+			esc[1] = SLIP_ESC_END;
+			break;
+		case SLIP_ESC:
+			esc[1] = SLIP_ESC_ESC;
+			break;
+		}
+		slip_print_bytes(esc, 2);
+		ret = serdev_device_write(sdev, esc, 2, timeout);
+		if (ret)
+			return ret;
+
+		last_idx = i;
+	}
+
+	slip_print_bytes(&buf[last_idx + 1], len - (last_idx + 1));
+
+	ret = serdev_device_write(sdev,
+		&buf[last_idx + 1], len - (last_idx + 1), timeout);
+
+	return ret;
+}
+#endif
+
+static int slip_write_data(u8 *buf, int buf_len, const u8 *data, int data_len)
+{
+	int last_idx = -1;
+	int i, n;
+	int count = 0;
+
+	for (i = 0; i < data_len; i++) {
+		if (data[i] != SLIP_END &&
+		    data[i] != SLIP_ESC)
+			continue;
+
+		n = i - (last_idx + 1);
+		if (count + n + 2 > buf_len)
+			return -ENOMEM;
+
+		memcpy(buf + count, &data[last_idx + 1], n);
+		count += n;
+
+		buf[count++] = SLIP_ESC;
+		switch (data[i]) {
+		case SLIP_END:
+			buf[count++] = SLIP_ESC_END;
+			break;
+		case SLIP_ESC:
+			buf[count++] = SLIP_ESC_ESC;
+			break;
+		}
+
+		last_idx = i;
+	}
+
+	n = data_len - (last_idx + 1);
+	if (count + n > buf_len)
+		return -ENOMEM;
+
+	memcpy(buf + count, &data[last_idx + 1], n);
+	count += n;
+
+	return count;
+}
+
+#define DEVMGMT_ID	0x01
+
+#define DEVMGMT_MSG_PING_REQ		0x01
+#define DEVMGMT_MSG_PING_RSP		0x02
+#define DEVMGMT_MSG_GET_DEVICE_INFO_REQ	0x03
+#define DEVMGMT_MSG_GET_DEVICE_INFO_RSP	0x04
+#define DEVMGMT_MSG_GET_FW_INFO_REQ	0x05
+#define DEVMGMT_MSG_GET_FW_INFO_RSP	0x06
+
+#define DEVMGMT_STATUS_OK	0x00
+
+struct wimod_hci_packet_dispatcher {
+	struct list_head list;
+	u8 dst_id;
+	u8 msg_id;
+	void (*dispatchee)(const u8*, int, struct wimod_hci_packet_dispatcher *);
+	void *priv;
+};
+
+struct wimod_hci_packet_completion {
+	struct wimod_hci_packet_dispatcher disp;
+	struct completion comp;
+	char *payload;
+	int payload_len;
+};
+
+static void wimod_hci_add_dispatcher(struct wimod_device *wmdev,
+	struct wimod_hci_packet_dispatcher *entry)
+{
+	list_add_tail_rcu(&entry->list, &wmdev->packet_dispatchers);
+}
+
+static void wimod_hci_remove_dispatcher(struct wimod_device *wmdev,
+	struct wimod_hci_packet_dispatcher *entry)
+{
+	list_del_rcu(&entry->list);
+}
+
+static void wimod_hci_packet_dispatch_completion(const u8 *data, int len,
+	struct wimod_hci_packet_dispatcher *d)
+{
+	struct wimod_hci_packet_completion *disp =
+		container_of(d, struct wimod_hci_packet_completion, disp);
+
+	if (completion_done(&disp->comp))
+		return;
+
+	disp->payload_len = len - 2;
+	disp->payload = kzalloc(disp->payload_len, GFP_KERNEL);
+	if (disp->payload)
+		memcpy(disp->payload, data + 2, len - 2);
+
+	complete(&disp->comp);
+}
+
+static int wimod_hci_send(struct serdev_device *sdev,
+	u8 dst_id, u8 msg_id, const u8 *payload, int payload_len,
+	unsigned long timeout)
+{
+	u8 buf[WIMOD_HCI_PACKET_MAX];
+	int buf_len = 0;
+	u16 crc = 0xffff;
+	int ret, i;
+
+	if (payload_len > WIMOD_HCI_PAYLOAD_MAX)
+		return -EINVAL;
+
+	for (i = 0; i < 30; i++) {
+		ret = slip_send_end(sdev, timeout);
+		if (ret) {
+			dev_err(&sdev->dev, "%s: wakeup END %d failed\n", __func__, i);
+			return ret;
+		}
+	}
+
+	crc = crc_ccitt_byte(crc, dst_id);
+	crc = crc_ccitt_byte(crc, msg_id);
+	if (payload_len > 0)
+		crc = crc_ccitt(crc, payload, payload_len);
+	crc = ~crc;
+
+	printk(KERN_INFO "sending: ");
+
+	/*ret = slip_send_end(sdev, timeout);
+	if (ret) {
+		dev_err(&sdev->dev, "%s: initial END failed\n", __func__);
+		return ret;
+	}
+
+	ret = slip_send_data(sdev, &dst_id, 1, timeout);
+	if (ret) {
+		dev_err(&sdev->dev, "%s: dst_id failed\n", __func__);
+		return ret;
+	}
+
+	ret = slip_send_data(sdev, &msg_id, 1, timeout);
+	if (ret) {
+		dev_err(&sdev->dev, "%s: msg_id failed\n", __func__);
+		return ret;
+	}*/
+
+	buf[buf_len++] = SLIP_END;
+
+	ret = slip_write_data(buf + buf_len, sizeof(buf) - buf_len, &dst_id, 1);
+	if (ret < 0)
+		return ret;
+	buf_len += ret;
+
+	ret = slip_write_data(buf + buf_len, sizeof(buf) - buf_len, &msg_id, 1);
+	if (ret < 0)
+		return ret;
+	buf_len += ret;
+
+	if (payload_len > 0) {
+		/*ret = slip_send_data(sdev, payload, payload_len, timeout);
+		if (ret) {
+			dev_err(&sdev->dev, "%s: payload failed\n", __func__);
+			return ret;
+		}*/
+		ret = slip_write_data(buf + buf_len, sizeof(buf) - buf_len, payload, payload_len);
+		if (ret < 0)
+			return ret;
+		buf_len += ret;
+	}
+
+	cpu_to_le16s(crc);
+	/*ret = slip_send_data(sdev, (u8 *)&crc, 2, timeout);
+	if (ret) {
+		dev_err(&sdev->dev, "%s: FCS failed\n", __func__);
+		return ret;
+	}
+
+	ret = slip_send_end(sdev, timeout);
+	if (ret) {
+		dev_err(&sdev->dev, "%s: trailing END failed\n", __func__);
+		return ret;
+	}*/
+
+	ret = slip_write_data(buf + buf_len, sizeof(buf) - buf_len, (u8 *)&crc, 2);
+	if (ret < 0)
+		return ret;
+	buf_len += ret;
+
+	buf[buf_len++] = SLIP_END;
+
+	slip_print_bytes(buf, buf_len);
+
+	return serdev_device_write(sdev, buf, buf_len, timeout);
+
+	//printk("\n");
+
+	//return 0;
+}
+
+static int wimod_hci_devmgmt_status(u8 status)
+{
+	switch (status) {
+	case DEVMGMT_STATUS_OK:
+		return 0;
+	default:
+		pr_info("DEVMGMT status %u\n", (int)status);
+		return -EINVAL;
+	}
+}
+
+static int wimod_hci_devmgmt_send_sync(struct wimod_device *wmdev,
+	u8 req_msg_id, const u8 *req_payload, int req_payload_len,
+	u8 rsp_msg_id, u8 **rsp_payload, int *rsp_payload_len,
+	unsigned long timeout)
+{
+	struct wimod_hci_packet_completion packet = {0};
+	int ret;
+
+	if (rsp_payload && !rsp_payload_len)
+		return -EINVAL;
+
+	packet.disp.dst_id = DEVMGMT_ID;
+	packet.disp.msg_id = rsp_msg_id;
+	packet.disp.dispatchee = wimod_hci_packet_dispatch_completion;
+	init_completion(&packet.comp);
+
+	wimod_hci_add_dispatcher(wmdev, &packet.disp);
+
+	ret = wimod_hci_send(wmdev->serdev, DEVMGMT_ID, req_msg_id, req_payload, req_payload_len, timeout);
+	if (ret) {
+		wimod_hci_remove_dispatcher(wmdev, &(packet.disp));
+		return ret;
+	}
+
+	timeout = wait_for_completion_timeout(&packet.comp, timeout);
+	wimod_hci_remove_dispatcher(wmdev, &packet.disp);
+	if (!timeout)
+		return -ETIMEDOUT;
+
+	if (packet.payload_len < 1) {
+		kfree(packet.payload);
+		return -EINVAL;
+	}
+
+	ret = wimod_hci_devmgmt_status(packet.payload[0]);
+	if (ret || !rsp_payload)
+		kfree(packet.payload);
+	else if (rsp_payload) {
+		*rsp_payload = packet.payload;
+		*rsp_payload_len = packet.payload_len;
+	}
+	return ret;
+}
+
+static int wimod_hci_ping(struct wimod_device *wmdev, unsigned long timeout)
+{
+	return wimod_hci_devmgmt_send_sync(wmdev,
+		DEVMGMT_MSG_PING_REQ, NULL, 0,
+		DEVMGMT_MSG_PING_RSP, NULL, NULL,
+		timeout);
+}
+
+static int wimod_hci_get_device_info(struct wimod_device *wmdev, u8 *buf, unsigned long timeout)
+{
+	u8 *payload;
+	int payload_len;
+	int ret;
+
+	ret = wimod_hci_devmgmt_send_sync(wmdev,
+		DEVMGMT_MSG_GET_DEVICE_INFO_REQ, NULL, 0,
+		DEVMGMT_MSG_GET_DEVICE_INFO_RSP, &payload, &payload_len,
+		timeout);
+	if (ret)
+		return ret;
+
+	if (payload_len < 10) {
+		dev_err(&wmdev->serdev->dev, "get_device_info: payload length (10)\n");
+		kfree(payload);
+		return -EINVAL;
+	}
+
+	if (buf)
+		memcpy(buf, payload + 1, min(payload_len - 1, 9));
+
+	kfree(payload);
+	return 0;
+}
+
+static int wimod_hci_get_fw_info(struct wimod_device *wmdev, u8 **info, int *info_len, unsigned long timeout)
+{
+	u8 *payload;
+	int payload_len;
+	int ret;
+
+	if (info && !info_len)
+		return -EINVAL;
+
+	ret = wimod_hci_devmgmt_send_sync(wmdev,
+		DEVMGMT_MSG_GET_FW_INFO_REQ, NULL, 0,
+		DEVMGMT_MSG_GET_FW_INFO_RSP, &payload, &payload_len,
+		timeout);
+	if (ret)
+		return ret;
+
+	if (info) {
+		*info = payload + 1;
+		*info_len = payload_len - 1;
+	} else
+		kfree(payload);
+
+	return 0;
+}
+
+static void wimod_hci_get_fw_info_free(u8* info)
+{
+	u8 *payload = info - 1;
+
+	kfree(payload);
+}
+
+static void wimod_process_packet(struct serdev_device *sdev, const u8 *data, int len)
+{
+	struct wimod_device *wmdev = serdev_device_get_drvdata(sdev);
+	struct wimod_hci_packet_dispatcher *e;
+	u16 crc;
+
+	dev_info(&sdev->dev, "Processing incoming packet (%d)\n", len);
+
+	if (len < 4) {
+		dev_dbg(&sdev->dev, "Discarding packet of length %d\n", len);
+		return;
+	}
+
+	crc = ~crc_ccitt(0xffff, data, len);
+	if (crc != 0x0f47) {
+		dev_dbg(&sdev->dev, "Discarding packet with wrong checksum\n");
+		return;
+	}
+
+	list_for_each_entry(e, &wmdev->packet_dispatchers, list) {
+		if (e->dst_id == data[0] && e->msg_id == data[1]) {
+			e->dispatchee(data, len - 2, e);
+			break;
+		}
+	}
+}
+
+static int wimod_receive_buf(struct serdev_device *sdev, const u8 *data, size_t count)
+{
+	struct wimod_device *wmdev = serdev_device_get_drvdata(sdev);
+	size_t i = 0;
+	int len = 0;
+
+	dev_dbg(&sdev->dev, "Receive (%d)\n", (int)count);
+
+	while (i < min(count, sizeof(wmdev->rx_buf) - wmdev->rx_len)) {
+		if (wmdev->rx_esc) {
+			wmdev->rx_esc = false;
+			switch (data[i]) {
+			case SLIP_ESC_END:
+				wmdev->rx_buf[wmdev->rx_len++] = SLIP_END;
+				break;
+			case SLIP_ESC_ESC:
+				wmdev->rx_buf[wmdev->rx_len++] = SLIP_ESC;
+				break;
+			default:
+				dev_warn(&sdev->dev, "Ignoring unknown escape sequence 0300 0%o\n", data[i]);
+				break;
+			}
+			len += i + 1;
+			data += i + 1;
+			count -= i + 1;
+			i = 0;
+			continue;
+		}
+		if (data[i] != SLIP_END &&
+		    data[i] != SLIP_ESC) {
+			i++;
+			continue;
+		}
+		if (i > 0) {
+			memcpy(&wmdev->rx_buf[wmdev->rx_len], data, i);
+			wmdev->rx_len += i;
+		}
+		if (data[i] == SLIP_END && wmdev->rx_len > 0) {
+			wimod_process_packet(sdev, wmdev->rx_buf, wmdev->rx_len);
+			wmdev->rx_len = 0;
+		} else if (data[i] == SLIP_ESC) {
+			wmdev->rx_esc = true;
+		}
+		len += i + 1;
+		data += i + 1;
+		count -= i + 1;
+		i = 0;
+	}
+
+	dev_dbg(&sdev->dev, "Receive: processed %d\n", len);
+
+	return len;
+}
+
+static const struct serdev_device_ops wimod_serdev_client_ops = {
+	.receive_buf = wimod_receive_buf,
+	.write_wakeup = serdev_device_write_wakeup,
+};
+
+static int wimod_probe(struct serdev_device *sdev)
+{
+	struct wimod_device *wmdev;
+	u8 buf[9];
+	u8 *data;
+	int data_len;
+	int ret;
+
+	dev_info(&sdev->dev, "Probing");
+
+	wmdev = devm_kzalloc(&sdev->dev, sizeof(struct wimod_device), GFP_KERNEL);
+	if (!wmdev)
+		return -ENOMEM;
+
+	wmdev->serdev = sdev;
+	INIT_LIST_HEAD(&wmdev->packet_dispatchers);
+	serdev_device_set_drvdata(sdev, wmdev);
+
+	ret = serdev_device_open(sdev);
+	if (ret) {
+		dev_err(&sdev->dev, "Failed to open (%d)\n", ret);
+		return ret;
+	}
+
+	serdev_device_set_baudrate(sdev, 115200);
+	serdev_device_set_flow_control(sdev, false);
+	serdev_device_set_client_ops(sdev, &wimod_serdev_client_ops);
+
+	ret = wimod_hci_ping(wmdev, HZ);
+	if (ret) {
+		dev_err(&sdev->dev, "Ping failed (%d)\n", ret);
+		goto err;
+	}
+
+	ret = wimod_hci_get_device_info(wmdev, buf, HZ);
+	if (ret) {
+		dev_err(&sdev->dev, "Failed to obtain device info (%d)\n", ret);
+		goto err;
+	}
+	dev_info(&sdev->dev, "Module type: 0x%02x\n", (int)buf[0]);
+
+	ret = wimod_hci_get_fw_info(wmdev, &data, &data_len, HZ);
+	if (ret) {
+		dev_err(&sdev->dev, "Failed to obtain firmware info (%d)\n", ret);
+		goto err;
+	}
+	dev_info(&sdev->dev, "Firmware: %u.%u build %u '%s'\n",
+		data[1], data[0], ((u16)data[3] << 8) | data[2], data + 4);
+	wimod_hci_get_fw_info_free(data);
+
+	dev_info(&sdev->dev, "Done.\n");
+
+	return 0;
+err:
+	serdev_device_close(sdev);
+	return ret;
+}
+
+static void wimod_remove(struct serdev_device *sdev)
+{
+	serdev_device_close(sdev);
+
+	dev_info(&sdev->dev, "Removed\n");
+}
+
+static const struct of_device_id wimod_of_match[] = {
+	{ .compatible = "imst,wimod-hci" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, wimod_of_match);
+
+static struct serdev_device_driver wimod_serdev_driver = {
+	.probe = wimod_probe,
+	.remove = wimod_remove,
+	.driver = {
+		.name = "wimod",
+		.of_match_table = wimod_of_match,
+	},
+};
+
+static int __init wimod_init(void)
+{
+	int ret;
+
+	ret = serdev_device_driver_register(&wimod_serdev_driver);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static void __exit wimod_exit(void)
+{
+	serdev_device_driver_unregister(&wimod_serdev_driver);
+}
+
+module_init(wimod_init);
+module_exit(wimod_exit);
+
+MODULE_DESCRIPTION("WiMOD serdev driver");
+MODULE_AUTHOR("Andreas Färber <afaerber@suse.de>");
+MODULE_LICENSE("GPL");
-- 
2.16.4