[RFC net-next 07/15] net: lora: Add Semtech SX1276

["Andreas Färber" <afaerber@suse.de>]

Semtech SX1276/77/78/79 and SX1272/73 are LoRa transceivers with a SPI
interface. They also offer a non-LoRa mode (not exposed here).

Signed-off-by: Andreas Färber <afaerber@suse.de>
---
 drivers/net/lora/Kconfig  |  11 +
 drivers/net/lora/Makefile |   3 +
 drivers/net/lora/sx1276.c | 608 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 622 insertions(+)
 create mode 100644 drivers/net/lora/sx1276.c

diff --git a/drivers/net/lora/Kconfig b/drivers/net/lora/Kconfig
index 40969b148a50..0436f6b09a1c 100644
--- a/drivers/net/lora/Kconfig
+++ b/drivers/net/lora/Kconfig
@@ -15,4 +15,15 @@ config LORA_DEV
 # Alphabetically sorted.
 #
 
+if LORA_DEV
+
+config LORA_SX1276
+	tristate "Semtech SX127x SPI driver"
+	default y
+	depends on SPI
+	help
+	  Semtech SX1272/1276/1278
+
+endif
+
 endmenu
diff --git a/drivers/net/lora/Makefile b/drivers/net/lora/Makefile
index 8f9d25ea4e70..8845542dba50 100644
--- a/drivers/net/lora/Makefile
+++ b/drivers/net/lora/Makefile
@@ -8,3 +8,6 @@ lora-dev-y := dev.o
 #
 # Alphabetically sorted.
 #
+
+obj-$(CONFIG_LORA_SX1276) += lora-sx1276.o
+lora-sx1276-y := sx1276.o
diff --git a/drivers/net/lora/sx1276.c b/drivers/net/lora/sx1276.c
new file mode 100644
index 000000000000..d6732111247a
--- /dev/null
+++ b/drivers/net/lora/sx1276.c
@@ -0,0 +1,608 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Semtech SX1272/SX1276 LoRa transceiver
+ *
+ * Copyright (c) 2016-2018 Andreas Färber
+ */
+
+#include <linux/delay.h>
+#include <linux/lora.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_gpio.h>
+#include <linux/lora/dev.h>
+#include <linux/spi/spi.h>
+
+#define REG_FIFO			0x00
+#define REG_OPMODE			0x01
+#define REG_FRF_MSB			0x06
+#define REG_FRF_MID			0x07
+#define REG_FRF_LSB			0x08
+#define REG_PA_CONFIG			0x09
+#define LORA_REG_FIFO_ADDR_PTR		0x0d
+#define LORA_REG_FIFO_TX_BASE_ADDR	0x0e
+#define LORA_REG_IRQ_FLAGS_MASK		0x11
+#define LORA_REG_IRQ_FLAGS		0x12
+#define LORA_REG_PAYLOAD_LENGTH		0x22
+#define LORA_REG_SYNC_WORD		0x39
+#define REG_DIO_MAPPING1		0x40
+#define REG_DIO_MAPPING2		0x41
+#define REG_VERSION			0x42
+#define REG_PA_DAC			0x4d
+
+#define REG_OPMODE_LONG_RANGE_MODE		BIT(7)
+#define REG_OPMODE_LOW_FREQUENCY_MODE_ON	BIT(3)
+#define REG_OPMODE_MODE_MASK			GENMASK(2, 0)
+#define REG_OPMODE_MODE_SLEEP			(0x0 << 0)
+#define REG_OPMODE_MODE_STDBY			(0x1 << 0)
+#define REG_OPMODE_MODE_TX			(0x3 << 0)
+#define REG_OPMODE_MODE_RXCONTINUOUS		(0x5 << 0)
+#define REG_OPMODE_MODE_RXSINGLE		(0x6 << 0)
+
+#define REG_PA_CONFIG_PA_SELECT			BIT(7)
+
+#define LORA_REG_IRQ_FLAGS_TX_DONE		BIT(3)
+
+#define REG_DIO_MAPPING1_DIO0_MASK	GENMASK(7, 6)
+
+struct sx1276_priv {
+	struct lora_priv lora;
+	struct spi_device *spi;
+
+	size_t fifosize;
+	int dio_gpio[6];
+
+	struct mutex spi_lock;
+
+	struct sk_buff *tx_skb;
+	int tx_len;
+
+	struct workqueue_struct *wq;
+	struct work_struct tx_work;
+};
+
+static int sx1276_read_single(struct spi_device *spi, u8 reg, u8 *val)
+{
+	u8 addr = reg & 0x7f;
+	return spi_write_then_read(spi, &addr, 1, val, 1);
+}
+
+static int sx1276_write_single(struct spi_device *spi, u8 reg, u8 val)
+{
+	u8 buf[2];
+
+	buf[0] = reg | BIT(7);
+	buf[1] = val;
+	return spi_write(spi, buf, 2);
+}
+
+static int sx1276_write_burst(struct spi_device *spi, u8 reg, size_t len, void *val)
+{
+	u8 buf = reg | BIT(7);
+	struct spi_transfer xfers[2] = {
+		[0] = {
+			.tx_buf = &buf,
+			.len = 1,
+		},
+		[1] = {
+			.tx_buf = val,
+			.len = len,
+		},
+	};
+
+	return spi_sync_transfer(spi, xfers, 2);
+}
+
+static int sx1276_write_fifo(struct spi_device *spi, size_t len, void *val)
+{
+	return sx1276_write_burst(spi, REG_FIFO, len, val);
+}
+
+static netdev_tx_t sx1276_loradev_start_xmit(struct sk_buff *skb, struct net_device *netdev)
+{
+	struct sx1276_priv *priv = netdev_priv(netdev);
+
+	netdev_dbg(netdev, "%s\n", __func__);
+
+	if (priv->tx_skb || priv->tx_len) {
+		netdev_warn(netdev, "TX busy\n");
+		return NETDEV_TX_BUSY;
+	}
+
+	if (skb->protocol != htons(ETH_P_LORA)) {
+		kfree_skb(skb);
+		netdev->stats.tx_dropped++;
+		return NETDEV_TX_OK;
+	}
+
+	netif_stop_queue(netdev);
+	priv->tx_skb = skb;
+	queue_work(priv->wq, &priv->tx_work);
+
+	return NETDEV_TX_OK;
+}
+
+static int sx1276_tx(struct spi_device *spi, void *data, int data_len)
+{
+	u8 addr, val;
+	int ret;
+
+	dev_dbg(&spi->dev, "%s\n", __func__);
+
+	ret = sx1276_read_single(spi, REG_OPMODE, &val);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to read RegOpMode (%d)\n", ret);
+		return ret;
+	}
+	dev_dbg(&spi->dev, "RegOpMode = 0x%02x\n", val);
+	if (!(val & REG_OPMODE_LONG_RANGE_MODE))
+		dev_err(&spi->dev, "LongRange Mode not active!\n");
+	if ((val & REG_OPMODE_MODE_MASK) == REG_OPMODE_MODE_SLEEP)
+		dev_err(&spi->dev, "Cannot access FIFO in Sleep Mode!\n");
+
+	ret = sx1276_read_single(spi, LORA_REG_FIFO_TX_BASE_ADDR, &addr);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to read RegFifoTxBaseAddr (%d)\n", ret);
+		return ret;
+	}
+	dev_dbg(&spi->dev, "RegFifoTxBaseAddr = 0x%02x\n", addr);
+
+	ret = sx1276_write_single(spi, LORA_REG_FIFO_ADDR_PTR, addr);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to write RegFifoAddrPtr (%d)\n", ret);
+		return ret;
+	}
+
+	ret = sx1276_write_single(spi, LORA_REG_PAYLOAD_LENGTH, data_len);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to write RegPayloadLength (%d)\n", ret);
+		return ret;
+	}
+
+	ret = sx1276_write_fifo(spi, data_len, data);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to write into FIFO (%d)\n", ret);
+		return ret;
+	}
+
+	ret = sx1276_read_single(spi, LORA_REG_IRQ_FLAGS, &val);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to read RegIrqFlags (%d)\n", ret);
+		return ret;
+	}
+	dev_dbg(&spi->dev, "RegIrqFlags = 0x%02x\n", val);
+
+	ret = sx1276_write_single(spi, LORA_REG_IRQ_FLAGS, LORA_REG_IRQ_FLAGS_TX_DONE);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to write RegIrqFlags (%d)\n", ret);
+		return ret;
+	}
+
+	ret = sx1276_read_single(spi, LORA_REG_IRQ_FLAGS_MASK, &val);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to read RegIrqFlagsMask (%d)\n", ret);
+		return ret;
+	}
+	dev_dbg(&spi->dev, "RegIrqFlagsMask = 0x%02x\n", val);
+
+	val &= ~LORA_REG_IRQ_FLAGS_TX_DONE;
+	ret = sx1276_write_single(spi, LORA_REG_IRQ_FLAGS_MASK, val);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to write RegIrqFlagsMask (%d)\n", ret);
+		return ret;
+	}
+
+	ret = sx1276_read_single(spi, REG_DIO_MAPPING1, &val);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to read RegDioMapping1 (%d)\n", ret);
+		return ret;
+	}
+
+	val &= ~REG_DIO_MAPPING1_DIO0_MASK;
+	val |= 0x1 << 6;
+	ret = sx1276_write_single(spi, REG_DIO_MAPPING1, val);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to write RegDioMapping1 (%d)\n", ret);
+		return ret;
+	}
+
+	ret = sx1276_read_single(spi, REG_OPMODE, &val);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to read RegOpMode (%d)\n", ret);
+		return ret;
+	}
+
+	val &= ~REG_OPMODE_MODE_MASK;
+	val |= REG_OPMODE_MODE_TX;
+	ret = sx1276_write_single(spi, REG_OPMODE, val);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to write RegOpMode (%d)\n", ret);
+		return ret;
+	}
+
+	dev_dbg(&spi->dev, "%s: done\n", __func__);
+
+	return 0;
+}
+
+static void sx1276_tx_work_handler(struct work_struct *ws)
+{
+	struct sx1276_priv *priv = container_of(ws, struct sx1276_priv, tx_work);
+	struct spi_device *spi = priv->spi;
+	struct net_device *netdev = spi_get_drvdata(spi);
+
+	netdev_dbg(netdev, "%s\n", __func__);
+
+	mutex_lock(&priv->spi_lock);
+
+	if (priv->tx_skb) {
+		sx1276_tx(spi, priv->tx_skb->data, priv->tx_skb->data_len);
+		priv->tx_len = 1 + priv->tx_skb->data_len;
+		if (!(netdev->flags & IFF_ECHO) ||
+			priv->tx_skb->pkt_type != PACKET_LOOPBACK ||
+			priv->tx_skb->protocol != htons(ETH_P_LORA))
+			kfree_skb(priv->tx_skb);
+		priv->tx_skb = NULL;
+	}
+
+	mutex_unlock(&priv->spi_lock);
+}
+
+static irqreturn_t sx1276_dio_interrupt(int irq, void *dev_id)
+{
+	struct net_device *netdev = dev_id;
+	struct sx1276_priv *priv = netdev_priv(netdev);
+	struct spi_device *spi = priv->spi;
+	u8 val;
+	int ret;
+
+	netdev_dbg(netdev, "%s\n", __func__);
+
+	mutex_lock(&priv->spi_lock);
+
+	ret = sx1276_read_single(spi, LORA_REG_IRQ_FLAGS, &val);
+	if (ret) {
+		netdev_warn(netdev, "Failed to read RegIrqFlags (%d)\n", ret);
+		val = 0;
+	}
+
+	if (val & LORA_REG_IRQ_FLAGS_TX_DONE) {
+		netdev_info(netdev, "TX done.\n");
+		netdev->stats.tx_packets++;
+		netdev->stats.tx_bytes += priv->tx_len - 1;
+		priv->tx_len = 0;
+		netif_wake_queue(netdev);
+
+		ret = sx1276_write_single(spi, LORA_REG_IRQ_FLAGS, LORA_REG_IRQ_FLAGS_TX_DONE);
+		if (ret)
+			netdev_warn(netdev, "Failed to write RegIrqFlags (%d)\n", ret);
+	}
+
+	mutex_unlock(&priv->spi_lock);
+
+	return IRQ_HANDLED;
+}
+
+static int sx1276_loradev_open(struct net_device *netdev)
+{
+	struct sx1276_priv *priv = netdev_priv(netdev);
+	struct spi_device *spi = to_spi_device(netdev->dev.parent);
+	u8 val;
+	int ret, irq;
+
+	netdev_dbg(netdev, "%s\n", __func__);
+
+	ret = open_loradev(netdev);
+	if (ret)
+		return ret;
+
+	mutex_lock(&priv->spi_lock);
+
+	ret = sx1276_read_single(spi, REG_OPMODE, &val);
+	if (ret) {
+		netdev_err(netdev, "Failed to read RegOpMode (%d)\n", ret);
+		goto err_opmode;
+	}
+
+	val &= ~REG_OPMODE_MODE_MASK;
+	val |= REG_OPMODE_MODE_STDBY;
+	ret = sx1276_write_single(spi, REG_OPMODE, val);
+	if (ret) {
+		netdev_err(netdev, "Failed to write RegOpMode (%d)\n", ret);
+		goto err_opmode;
+	}
+
+	priv->tx_skb = NULL;
+	priv->tx_len = 0;
+
+	priv->wq = alloc_workqueue("sx1276_wq", WQ_FREEZABLE | WQ_MEM_RECLAIM, 0);
+	INIT_WORK(&priv->tx_work, sx1276_tx_work_handler);
+
+	if (gpio_is_valid(priv->dio_gpio[0])) {
+		irq = gpio_to_irq(priv->dio_gpio[0]);
+		if (irq <= 0)
+			netdev_warn(netdev, "Failed to obtain interrupt for DIO0 (%d)\n", irq);
+		else {
+			netdev_info(netdev, "Succeeded in obtaining interrupt for DIO0: %d\n", irq);
+			ret = request_threaded_irq(irq, NULL, sx1276_dio_interrupt, IRQF_ONESHOT | IRQF_TRIGGER_RISING, netdev->name, netdev);
+			if (ret) {
+				netdev_err(netdev, "Failed to request interrupt for DIO0 (%d)\n", ret);
+				goto err_irq;
+			}
+		}
+	}
+
+	netif_wake_queue(netdev);
+
+	mutex_unlock(&priv->spi_lock);
+
+	return 0;
+
+err_irq:
+	destroy_workqueue(priv->wq);
+	priv->wq = NULL;
+err_opmode:
+	close_loradev(netdev);
+	mutex_unlock(&priv->spi_lock);
+	return ret;
+}
+
+static int sx1276_loradev_stop(struct net_device *netdev)
+{
+	struct sx1276_priv *priv = netdev_priv(netdev);
+	struct spi_device *spi = to_spi_device(netdev->dev.parent);
+	u8 val;
+	int ret, irq;
+
+	netdev_dbg(netdev, "%s\n", __func__);
+
+	close_loradev(netdev);
+
+	mutex_lock(&priv->spi_lock);
+
+	ret = sx1276_write_single(spi, LORA_REG_IRQ_FLAGS_MASK, 0xff);
+	if (ret) {
+		netdev_err(netdev, "Failed to write RegIrqFlagsMask (%d)\n", ret);
+		goto err_irqmask;
+	}
+
+	ret = sx1276_read_single(spi, REG_OPMODE, &val);
+	if (ret) {
+		netdev_err(netdev, "Failed to read RegOpMode (%d)\n", ret);
+		goto err_opmode;
+	}
+
+	val &= ~REG_OPMODE_MODE_MASK;
+	val |= REG_OPMODE_MODE_SLEEP;
+	ret = sx1276_write_single(spi, REG_OPMODE, val);
+	if (ret) {
+		netdev_err(netdev, "Failed to write RegOpMode (%d)\n", ret);
+		goto err_opmode;
+	}
+
+	if (gpio_is_valid(priv->dio_gpio[0])) {
+		irq = gpio_to_irq(priv->dio_gpio[0]);
+		if (irq > 0) {
+			netdev_dbg(netdev, "Freeing IRQ %d\n", irq);
+			free_irq(irq, netdev);
+		}
+	}
+
+	destroy_workqueue(priv->wq);
+	priv->wq = NULL;
+
+	if (priv->tx_skb || priv->tx_len)
+		netdev->stats.tx_errors++;
+	if (priv->tx_skb)
+		dev_kfree_skb(priv->tx_skb);
+	priv->tx_skb = NULL;
+	priv->tx_len = 0;
+
+	mutex_unlock(&priv->spi_lock);
+
+	return 0;
+
+err_opmode:
+err_irqmask:
+	mutex_unlock(&priv->spi_lock);
+	return ret;
+}
+
+static const struct net_device_ops sx1276_netdev_ops =  {
+	.ndo_open = sx1276_loradev_open,
+	.ndo_stop = sx1276_loradev_stop,
+	.ndo_start_xmit = sx1276_loradev_start_xmit,
+};
+
+static int sx1276_probe(struct spi_device *spi)
+{
+	struct net_device *netdev;
+	struct sx1276_priv *priv;
+	int rst, dio[6], ret, model, i;
+	u32 freq_xosc, freq_band;
+	unsigned long long freq_rf;
+	u8 val;
+
+	rst = of_get_named_gpio(spi->dev.of_node, "reset-gpio", 0);
+	if (rst == -ENOENT)
+		dev_warn(&spi->dev, "no reset GPIO available, ignoring");
+
+	for (i = 0; i < 6; i++) {
+		dio[i] = of_get_named_gpio(spi->dev.of_node, "dio-gpios", i);
+		if (dio[i] == -ENOENT)
+			dev_dbg(&spi->dev, "DIO%d not available, ignoring", i);
+		else {
+			ret = gpio_direction_input(dio[i]);
+			if (ret)
+				dev_err(&spi->dev, "couldn't set DIO%d to input", i);
+		}
+	}
+
+	if (gpio_is_valid(rst)) {
+		gpio_set_value(rst, 1);
+		udelay(100);
+		gpio_set_value(rst, 0);
+		msleep(5);
+	}
+
+	spi->bits_per_word = 8;
+	spi_setup(spi);
+
+	ret = sx1276_read_single(spi, REG_VERSION, &val);
+	if (ret) {
+		dev_err(&spi->dev, "version read failed");
+		return ret;
+	}
+
+	if (val == 0x22)
+		model = 1272;
+	else {
+		if (gpio_is_valid(rst)) {
+			gpio_set_value(rst, 0);
+			udelay(100);
+			gpio_set_value(rst, 1);
+			msleep(5);
+		}
+
+		ret = sx1276_read_single(spi, REG_VERSION, &val);
+		if (ret) {
+			dev_err(&spi->dev, "version read failed");
+			return ret;
+		}
+
+		if (val == 0x12)
+			model = 1276;
+		else {
+			dev_err(&spi->dev, "transceiver not recognized (RegVersion = 0x%02x)", (unsigned)val);
+			return -EINVAL;
+		}
+	}
+
+	ret = of_property_read_u32(spi->dev.of_node, "clock-frequency", &freq_xosc);
+	if (ret) {
+		dev_err(&spi->dev, "failed reading clock-frequency");
+		return ret;
+	}
+
+	ret = of_property_read_u32(spi->dev.of_node, "radio-frequency", &freq_band);
+	if (ret) {
+		dev_err(&spi->dev, "failed reading radio-frequency");
+		return ret;
+	}
+
+	val = REG_OPMODE_LONG_RANGE_MODE | REG_OPMODE_MODE_SLEEP;
+	if (freq_band < 525000000)
+		val |= REG_OPMODE_LOW_FREQUENCY_MODE_ON;
+	ret = sx1276_write_single(spi, REG_OPMODE, val);
+	if (ret) {
+		dev_err(&spi->dev, "failed writing opmode");
+		return ret;
+	}
+
+	freq_rf = freq_band;
+	freq_rf *= (1 << 19);
+	freq_rf /= freq_xosc;
+	dev_dbg(&spi->dev, "Frf = %llu", freq_rf);
+
+	ret = sx1276_write_single(spi, REG_FRF_MSB, freq_rf >> 16);
+	if (!ret)
+		ret = sx1276_write_single(spi, REG_FRF_MID, freq_rf >> 8);
+	if (!ret)
+		ret = sx1276_write_single(spi, REG_FRF_LSB, freq_rf);
+	if (ret) {
+		dev_err(&spi->dev, "failed writing frequency (%d)", ret);
+		return ret;
+	}
+
+	ret = sx1276_read_single(spi, REG_PA_CONFIG, &val);
+	if (ret) {
+		dev_err(&spi->dev, "failed reading RegPaConfig\n");
+		return ret;
+	}
+	if (true)
+		val |= REG_PA_CONFIG_PA_SELECT;
+	val &= ~GENMASK(3, 0);
+	val |= (23 - 3) - 5;
+	ret = sx1276_write_single(spi, REG_PA_CONFIG, val);
+	if (ret) {
+		dev_err(&spi->dev, "failed writing RegPaConfig\n");
+		return ret;
+	}
+
+	ret = sx1276_read_single(spi, REG_PA_DAC, &val);
+	if (ret) {
+		dev_err(&spi->dev, "failed reading RegPaDac\n");
+		return ret;
+	}
+	val &= ~GENMASK(2, 0);
+	val |= 0x7;
+	ret = sx1276_write_single(spi, REG_PA_DAC, val);
+	if (ret) {
+		dev_err(&spi->dev, "failed writing RegPaDac\n");
+		return ret;
+	}
+
+	netdev = alloc_loradev(sizeof(struct sx1276_priv));
+	if (!netdev)
+		return -ENOMEM;
+
+	netdev->netdev_ops = &sx1276_netdev_ops;
+	netdev->flags |= IFF_ECHO;
+
+	priv = netdev_priv(netdev);
+	priv->spi = spi;
+	mutex_init(&priv->spi_lock);
+	for (i = 0; i < 6; i++)
+		priv->dio_gpio[i] = dio[i];
+
+	spi_set_drvdata(spi, netdev);
+	SET_NETDEV_DEV(netdev, &spi->dev);
+
+	ret = register_loradev(netdev);
+	if (ret) {
+		free_loradev(netdev);
+		return ret;
+	}
+
+	dev_info(&spi->dev, "SX1276 module probed (SX%d)", model);
+
+	return 0;
+}
+
+static int sx1276_remove(struct spi_device *spi)
+{
+	struct net_device *netdev = spi_get_drvdata(spi);
+
+	unregister_loradev(netdev);
+	free_loradev(netdev);
+
+	dev_info(&spi->dev, "SX1276 module removed");
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id sx1276_dt_ids[] = {
+	{ .compatible = "semtech,sx1272" },
+	{ .compatible = "semtech,sx1276" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, sx1276_dt_ids);
+#endif
+
+static struct spi_driver sx1276_spi_driver = {
+	.driver = {
+		.name = "sx1276",
+		.of_match_table = of_match_ptr(sx1276_dt_ids),
+	},
+	.probe = sx1276_probe,
+	.remove = sx1276_remove,
+};
+
+module_spi_driver(sx1276_spi_driver);
+
+MODULE_DESCRIPTION("SX1276 SPI driver");
+MODULE_AUTHOR("Andreas Färber <afaerber@suse.de>");
+MODULE_LICENSE("GPL");
-- 
2.16.4