[RFC net-next 10/15] net: lora: Add Microchip RN2483

["Andreas Färber" <afaerber@suse.de>]

The Microchip RN2483 and RN2903 are UART based modules exposing both
LoRaWAN and LoRa. The RN2483 supports switching between 433 and 868 MHz.

Signed-off-by: Andreas Färber <afaerber@suse.de>
---
 drivers/net/lora/Kconfig      |   7 +
 drivers/net/lora/Makefile     |   4 +
 drivers/net/lora/rn2483.c     | 344 ++++++++++++++++++++++++++++++++++++++++++
 drivers/net/lora/rn2483.h     |  40 +++++
 drivers/net/lora/rn2483_cmd.c | 130 ++++++++++++++++
 5 files changed, 525 insertions(+)
 create mode 100644 drivers/net/lora/rn2483.c
 create mode 100644 drivers/net/lora/rn2483.h
 create mode 100644 drivers/net/lora/rn2483_cmd.c

diff --git a/drivers/net/lora/Kconfig b/drivers/net/lora/Kconfig
index 0436f6b09a1c..940bd2cbe106 100644
--- a/drivers/net/lora/Kconfig
+++ b/drivers/net/lora/Kconfig
@@ -17,6 +17,13 @@ config LORA_DEV
 
 if LORA_DEV
 
+config LORA_RN2483
+	tristate "Microchip RN2483/RN2903 driver"
+	default y
+	depends on SERIAL_DEV_BUS
+	help
+	  Microchip RN2483/2903
+
 config LORA_SX1276
 	tristate "Semtech SX127x SPI driver"
 	default y
diff --git a/drivers/net/lora/Makefile b/drivers/net/lora/Makefile
index 8845542dba50..07839c3ce9f8 100644
--- a/drivers/net/lora/Makefile
+++ b/drivers/net/lora/Makefile
@@ -9,5 +9,9 @@ lora-dev-y := dev.o
 # Alphabetically sorted.
 #
 
+obj-$(CONFIG_LORA_RN2483) += lora-rn2483.o
+lora-rn2483-y := rn2483.o
+lora-rn2483-y += rn2483_cmd.o
+
 obj-$(CONFIG_LORA_SX1276) += lora-sx1276.o
 lora-sx1276-y := sx1276.o
diff --git a/drivers/net/lora/rn2483.c b/drivers/net/lora/rn2483.c
new file mode 100644
index 000000000000..8b9ec2575ee2
--- /dev/null
+++ b/drivers/net/lora/rn2483.c
@@ -0,0 +1,344 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Microchip RN2483/RN2903
+ *
+ * Copyright (c) 2017-2018 Andreas Färber
+ */
+
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/lora.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/of.h>
+#include <linux/serdev.h>
+#include <linux/lora/dev.h>
+
+#include "rn2483.h"
+
+struct rn2483_priv {
+	struct lora_priv lora;
+};
+
+static netdev_tx_t rn2483_loradev_start_xmit(struct sk_buff *skb, struct net_device *netdev)
+{
+	if (skb->protocol != htons(ETH_P_LORA)) {
+		kfree_skb(skb);
+		netdev->stats.tx_dropped++;
+		return NETDEV_TX_OK;
+	}
+
+	netif_stop_queue(netdev);
+
+	/* TODO */
+	return NETDEV_TX_OK;
+}
+
+static int rn2483_loradev_open(struct net_device *netdev)
+{
+	int ret;
+
+	netdev_dbg(netdev, "%s", __func__);
+
+	ret = open_loradev(netdev);
+	if (ret)
+		return ret;
+
+	netif_start_queue(netdev);
+
+	return 0;
+}
+
+static int rn2483_loradev_stop(struct net_device *netdev)
+{
+	netdev_dbg(netdev, "%s", __func__);
+
+	netif_stop_queue(netdev);
+	close_loradev(netdev);
+
+	return 0;
+}
+
+static const struct net_device_ops rn2483_net_device_ops = {
+	.ndo_open = rn2483_loradev_open,
+	.ndo_stop = rn2483_loradev_stop,
+	.ndo_start_xmit = rn2483_loradev_start_xmit,
+};
+
+int rn2483_readline_timeout(struct rn2483_device *rndev, char **line, unsigned long timeout)
+{
+	timeout = wait_for_completion_timeout(&rndev->line_recv_comp, timeout);
+	if (!timeout)
+		return -ETIMEDOUT;
+
+	*line = devm_kstrdup(&rndev->serdev->dev, rndev->buf, GFP_KERNEL);
+	complete(&rndev->line_read_comp);
+	if (!*line)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void rn2483_receive_line(struct rn2483_device *rndev, const char *sz, size_t len)
+{
+	dev_dbg(&rndev->serdev->dev, "Received line '%s' (%d)", sz, (int)len);
+
+	reinit_completion(&rndev->line_read_comp);
+	complete(&rndev->line_recv_comp);
+	wait_for_completion(&rndev->line_read_comp);
+	reinit_completion(&rndev->line_recv_comp);
+}
+
+static int rn2483_receive_buf(struct serdev_device *serdev, const u8 *data, size_t count)
+{
+	struct rn2483_device *rndev = serdev_device_get_drvdata(serdev);
+	size_t i;
+
+	dev_dbg(&serdev->dev, "Receive (%d)", (int)count);
+	if (!rndev->buf) {
+		rndev->buf = devm_kmalloc(&serdev->dev, count, GFP_KERNEL);
+		if (!rndev->buf)
+			return 0;
+		rndev->buflen = 0;
+	} else {
+		void *tmp = devm_kmalloc(&serdev->dev, rndev->buflen + count, GFP_KERNEL);
+		if (!tmp)
+			return 0;
+		memcpy(tmp, rndev->buf, rndev->buflen);
+		devm_kfree(&serdev->dev, rndev->buf);
+		rndev->buf = tmp;
+	}
+
+	for (i = 0; i < count; i++) {
+		if (data[i] == '\r') {
+			rndev->saw_cr = true;
+		} else if (data[i] == '\n' && rndev->saw_cr) {
+			if (i > 1)
+				memcpy(rndev->buf + rndev->buflen, data, i - 1);
+			((char *)rndev->buf)[rndev->buflen + i - 1] = 0;
+			rn2483_receive_line(rndev, rndev->buf, rndev->buflen + i - 1);
+			rndev->saw_cr = false;
+			devm_kfree(&serdev->dev, rndev->buf);
+			rndev->buf = NULL;
+			rndev->buflen = 0;
+			return i + 1;
+		} else
+			rndev->saw_cr = false;
+	}
+
+	memcpy(rndev->buf + rndev->buflen, data, count);
+	rndev->buflen += count;
+	return count;
+}
+
+static const struct serdev_device_ops rn2483_serdev_client_ops = {
+	.receive_buf = rn2483_receive_buf,
+};
+
+static int rn2483_probe(struct serdev_device *sdev)
+{
+	struct rn2483_device *rndev;
+	char *line, *cmd;
+	char sz[5];
+	u32 status;
+	int ret;
+
+	dev_info(&sdev->dev, "Probing");
+
+	rndev = devm_kzalloc(&sdev->dev, sizeof(struct rn2483_device), GFP_KERNEL);
+	if (!rndev)
+		return -ENOMEM;
+
+	rndev->serdev = sdev;
+	init_completion(&rndev->line_recv_comp);
+	init_completion(&rndev->line_read_comp);
+	mutex_init(&rndev->cmd_lock);
+	serdev_device_set_drvdata(sdev, rndev);
+
+	rndev->reset_gpio = devm_gpiod_get_optional(&sdev->dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(rndev->reset_gpio))
+		return PTR_ERR(rndev->reset_gpio);
+
+	ret = serdev_device_open(sdev);
+	if (ret) {
+		dev_err(&sdev->dev, "Failed to open (%d)", ret);
+		return ret;
+	}
+
+	serdev_device_set_baudrate(sdev, 57600);
+	serdev_device_set_flow_control(sdev, false);
+
+	gpiod_set_value_cansleep(rndev->reset_gpio, 0);
+	msleep(5);
+	serdev_device_set_client_ops(sdev, &rn2483_serdev_client_ops);
+	gpiod_set_value_cansleep(rndev->reset_gpio, 1);
+	msleep(100);
+
+	ret = rn2483_readline_timeout(rndev, &line, HZ);
+	if (ret) {
+		if (ret != -ENOMEM)
+			dev_err(&sdev->dev, "Timeout waiting for firmware identification");
+		goto err_timeout;
+	}
+
+	if (strlen(line) < strlen("RNxxxx X.Y.Z MMM DD YYYY HH:MM:SS") || line[6] != ' ' ||
+			strncmp(line, "RN", 2) != 0) {
+		dev_err(&sdev->dev, "Unexpected response '%s'", line);
+		devm_kfree(&sdev->dev, line);
+		ret = -EINVAL;
+		goto err_version;
+	}
+	dev_info(&sdev->dev, "Firmware '%s'", line);
+	strncpy(sz, line + 2, 4);
+	sz[4] = 0;
+	devm_kfree(&sdev->dev, line);
+	ret = kstrtouint(sz, 10, &rndev->model);
+	if (ret)
+		goto err_model;
+	if (!(rndev->model == 2483 || rndev->model == 2903)) {
+		dev_err(&sdev->dev, "Unknown model %u", rndev->model);
+		ret = -ENOTSUPP;
+		goto err_model;
+	}
+	dev_info(&sdev->dev, "Detected RN%u", rndev->model);
+
+	ret = rn2483_sys_get_hweui(rndev, &rndev->hweui);
+	if (ret) {
+		if (ret != -ENOMEM)
+			dev_err(&sdev->dev, "Failed to read HWEUI (%d)", ret);
+		goto err_hweui;
+	}
+	dev_info(&sdev->dev, "HWEUI " PRIxLORAEUI, LORA_EUI(rndev->hweui));
+
+	switch (rndev->model) {
+	case 2483:
+		ret = rn2483_mac_get_band(rndev, &rndev->band);
+		if (ret) {
+			dev_err(&sdev->dev, "Failed to read band (%d)", ret);
+			goto err_band;
+		}
+		dev_info(&sdev->dev, "Frequency band %u MHz", rndev->band);
+
+		ret = rn2483_mac_reset_band(rndev, 433);
+		if (ret) {
+			dev_err(&sdev->dev, "Failed to reset band (%d)", ret);
+			goto err_band;
+		}
+		rndev->band = 433;
+
+		ret = rn2483_mac_get_band(rndev, &rndev->band);
+		if (!ret)
+			dev_info(&sdev->dev, "New frequency band: %u MHz", rndev->band);
+		break;
+	case 2903:
+		/* No "mac get band" command available */
+		rndev->band = 915;
+		break;
+	}
+
+	ret = rn2483_mac_get_status(rndev, &status);
+	if (!ret)
+		dev_info(&sdev->dev, "MAC status %08x", status);
+
+	if (true) {
+		u32 pause;
+		ret = rn2483_mac_pause(rndev, &pause);
+		if (!ret)
+			dev_info(&sdev->dev, "MAC pausing (0x%08x)", pause);
+		ret = rn2483_mac_resume(rndev);
+		if (!ret)
+			dev_info(&sdev->dev, "MAC resuming");
+	}
+
+	cmd = "mac get sync";
+	mutex_lock(&rndev->cmd_lock);
+	ret = rn2483_send_command_timeout(rndev, cmd, &line, HZ);
+	mutex_unlock(&rndev->cmd_lock);
+	if (!ret) {
+		dev_info(&sdev->dev, "%s => '%s'", cmd, line);
+		devm_kfree(&sdev->dev, line);
+	}
+
+	rndev->netdev = alloc_loradev(sizeof(struct rn2483_priv));
+	if (!rndev->netdev) {
+		ret = -ENOMEM;
+		goto err_alloc_netdev;
+	}
+
+	rndev->netdev->netdev_ops = &rn2483_net_device_ops;
+	SET_NETDEV_DEV(rndev->netdev, &sdev->dev);
+
+	ret = register_loradev(rndev->netdev);
+	if (ret)
+		goto err_register_netdev;
+
+	dev_info(&sdev->dev, "Done.");
+
+	return 0;
+
+err_register_netdev:
+	free_loradev(rndev->netdev);
+err_alloc_netdev:
+err_band:
+err_hweui:
+err_model:
+err_version:
+err_timeout:
+	gpiod_set_value_cansleep(rndev->reset_gpio, 0);
+	return ret;
+}
+
+static void rn2483_remove(struct serdev_device *sdev)
+{
+	struct rn2483_device *rndev = serdev_device_get_drvdata(sdev);
+
+	unregister_loradev(rndev->netdev);
+	free_loradev(rndev->netdev);
+
+	gpiod_set_value_cansleep(rndev->reset_gpio, 0);
+
+	complete(&rndev->line_read_comp);
+
+	serdev_device_close(sdev);
+
+	dev_info(&sdev->dev, "Removed");
+}
+
+static const struct of_device_id rn2483_of_match[] = {
+	{ .compatible = "microchip,rn2483" },
+	{ .compatible = "microchip,rn2903" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, rn2483_of_match);
+
+static struct serdev_device_driver rn2483_serdev_driver = {
+	.probe = rn2483_probe,
+	.remove = rn2483_remove,
+	.driver = {
+		.name = "rn2483",
+		.of_match_table = rn2483_of_match,
+	},
+};
+
+static int __init rn2483_init(void)
+{
+	int ret;
+
+	ret = serdev_device_driver_register(&rn2483_serdev_driver);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static void __exit rn2483_exit(void)
+{
+	serdev_device_driver_unregister(&rn2483_serdev_driver);
+}
+
+module_init(rn2483_init);
+module_exit(rn2483_exit);
+
+MODULE_DESCRIPTION("RN2483 serdev driver");
+MODULE_AUTHOR("Andreas Färber <afaerber@suse.de>");
+MODULE_LICENSE("GPL");
diff --git a/drivers/net/lora/rn2483.h b/drivers/net/lora/rn2483.h
new file mode 100644
index 000000000000..f92660286f15
--- /dev/null
+++ b/drivers/net/lora/rn2483.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (c) 2017-2018 Andreas Färber
+ */
+#ifndef _RN2483_H
+#define _RN2483_H
+
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/netdevice.h>
+#include <linux/serdev.h>
+#include <linux/lora/dev.h>
+
+struct rn2483_device {
+	struct serdev_device *serdev;
+	struct gpio_desc *reset_gpio;
+	struct net_device *netdev;
+	unsigned model;
+	lora_eui hweui;
+	unsigned band;
+	bool saw_cr;
+	void *buf;
+	size_t buflen;
+	struct completion line_recv_comp;
+	struct completion line_read_comp;
+	struct mutex cmd_lock;
+};
+
+int rn2483_readline_timeout(struct rn2483_device *rndev, char **line, unsigned long timeout);
+int rn2483_send_command_timeout(struct rn2483_device *rndev,
+	const char *cmd, char **resp, unsigned long timeout);
+
+int rn2483_sys_get_hweui(struct rn2483_device *rndev, lora_eui *val);
+int rn2483_mac_get_band(struct rn2483_device *rndev, uint *val);
+int rn2483_mac_get_status(struct rn2483_device *rndev, u32 *val);
+int rn2483_mac_reset_band(struct rn2483_device *rndev, unsigned band);
+int rn2483_mac_pause(struct rn2483_device *rndev, u32 *max_pause);
+int rn2483_mac_resume(struct rn2483_device *rndev);
+
+#endif
diff --git a/drivers/net/lora/rn2483_cmd.c b/drivers/net/lora/rn2483_cmd.c
new file mode 100644
index 000000000000..6d6fca8fa93c
--- /dev/null
+++ b/drivers/net/lora/rn2483_cmd.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Microchip RN2483/RN2903 - UART commands
+ *
+ * Copyright (c) 2017-2018 Andreas Färber
+ */
+#include "rn2483.h"
+
+#define RN2483_CMD_TIMEOUT HZ
+
+int rn2483_send_command_timeout(struct rn2483_device *rndev,
+	const char *cmd, char **resp, unsigned long timeout)
+{
+	int ret;
+
+	ret = serdev_device_write_buf(rndev->serdev, cmd, strlen(cmd));
+	if (ret < 0)
+		return ret;
+
+	ret = serdev_device_write_buf(rndev->serdev, "\r\n", 2);
+	if (ret < 0)
+		return ret;
+
+	return rn2483_readline_timeout(rndev, resp, timeout);
+}
+
+int rn2483_sys_get_hweui(struct rn2483_device *rndev, lora_eui *val)
+{
+	int ret;
+	char *line;
+
+	mutex_lock(&rndev->cmd_lock);
+	ret = rn2483_send_command_timeout(rndev, "sys get hweui", &line, RN2483_CMD_TIMEOUT);
+	mutex_unlock(&rndev->cmd_lock);
+	if (ret)
+		return ret;
+
+	ret = lora_strtoeui(line, val);
+	devm_kfree(&rndev->serdev->dev, line);
+	return ret;
+}
+
+int rn2483_mac_get_band(struct rn2483_device *rndev, uint *val)
+{
+	int ret;
+	char *line;
+
+	mutex_lock(&rndev->cmd_lock);
+	ret = rn2483_send_command_timeout(rndev, "mac get band", &line, RN2483_CMD_TIMEOUT);
+	mutex_unlock(&rndev->cmd_lock);
+	if (ret)
+		return ret;
+
+	ret = kstrtouint(line, 10, val);
+	devm_kfree(&rndev->serdev->dev, line);
+
+	return ret;
+}
+
+int rn2483_mac_get_status(struct rn2483_device *rndev, u32 *val)
+{
+	int ret;
+	char *line;
+
+	mutex_lock(&rndev->cmd_lock);
+	ret = rn2483_send_command_timeout(rndev, "mac get status", &line, RN2483_CMD_TIMEOUT);
+	mutex_unlock(&rndev->cmd_lock);
+	if (ret)
+		return ret;
+
+	ret = kstrtou32(line, 16, val);
+	devm_kfree(&rndev->serdev->dev, line);
+	return ret;
+}
+
+int rn2483_mac_reset_band(struct rn2483_device *rndev, unsigned band)
+{
+	int ret;
+	char *line, *cmd;
+
+	cmd = devm_kasprintf(&rndev->serdev->dev, GFP_KERNEL, "mac reset %u", band);
+	mutex_lock(&rndev->cmd_lock);
+	ret = rn2483_send_command_timeout(rndev, cmd, &line, RN2483_CMD_TIMEOUT);
+	mutex_unlock(&rndev->cmd_lock);
+	devm_kfree(&rndev->serdev->dev, cmd);
+	if (ret)
+		return ret;
+
+	if (strcmp(line, "ok") == 0)
+		ret = 0;
+	else if (strcmp(line, "invalid_param") == 0)
+		ret = -EINVAL;
+	else
+		ret = -EPROTO;
+
+	devm_kfree(&rndev->serdev->dev, line);
+	return ret;
+}
+
+int rn2483_mac_pause(struct rn2483_device *rndev, u32 *max_pause)
+{
+	int ret;
+	char *line;
+
+	mutex_lock(&rndev->cmd_lock);
+	ret = rn2483_send_command_timeout(rndev, "mac pause", &line, RN2483_CMD_TIMEOUT);
+	mutex_unlock(&rndev->cmd_lock);
+	if (ret)
+		return ret;
+
+	ret = kstrtou32(line, 10, max_pause);
+	devm_kfree(&rndev->serdev->dev, line);
+	return ret;
+}
+
+int rn2483_mac_resume(struct rn2483_device *rndev)
+{
+	int ret;
+	char *line;
+
+	mutex_lock(&rndev->cmd_lock);
+	ret = rn2483_send_command_timeout(rndev, "mac resume", &line, RN2483_CMD_TIMEOUT);
+	mutex_unlock(&rndev->cmd_lock);
+	if (ret)
+		return ret;
+
+	ret = (strcmp(line, "ok") == 0) ? 0 : -EPROTO;
+	devm_kfree(&rndev->serdev->dev, line);
+	return ret;
+}
-- 
2.16.4