[RFC net-next 15/15] net: lora: Add Semtech SX1301

["Andreas Färber" <afaerber@suse.de>]

The Semtech SX1301 was the first multi-channel LoRa "concentrator".
It uses a SPI interface to the host as well as a dual SPI interface to
its radios. These two have been implemented as spi_controller, so that
the Device Tree can specify whether the respective module uses two
SX1257, two SX1255 or a combination of these or some unforeseen chipset.

This implementation is the most recent - initialization is not yet
complete, it will need to load firmware into the two on-chip MCUs.

Unfortunately there is no full datasheet with register descriptions,
only a BSD-licensed userspace HAL implementation using spidev devices.
Therefore some register names are unknown.

Cc: Ben Whitten <ben.whitten@lairdtech.com>
Cc: Steve deRosier <derosier@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Michael Röder <michael.roeder@avnet.eu>
Cc: Ken Yu (禹凯) <ken.yu@rakwireless.com>
Cc: linux-spi@vger.kernel.org
Signed-off-by: Andreas Färber <afaerber@suse.de>
---
 drivers/net/lora/Kconfig  |   7 +
 drivers/net/lora/Makefile |   3 +
 drivers/net/lora/sx1301.c | 446 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 456 insertions(+)
 create mode 100644 drivers/net/lora/sx1301.c

diff --git a/drivers/net/lora/Kconfig b/drivers/net/lora/Kconfig
index 68c7480d7812..950450e353b4 100644
--- a/drivers/net/lora/Kconfig
+++ b/drivers/net/lora/Kconfig
@@ -45,6 +45,13 @@ config LORA_SX1276
 	help
 	  Semtech SX1272/1276/1278
 
+config LORA_SX1301
+	tristate "Semtech SX1301 SPI driver"
+	default y
+	depends on SPI
+	help
+	  Semtech SX1301
+
 config LORA_USI
 	tristate "USI WM-SG-SM-42 driver"
 	default y
diff --git a/drivers/net/lora/Makefile b/drivers/net/lora/Makefile
index 44c578bde7d5..1cc1e3aa189b 100644
--- a/drivers/net/lora/Makefile
+++ b/drivers/net/lora/Makefile
@@ -22,6 +22,9 @@ lora-sx1257-y := sx1257.o
 obj-$(CONFIG_LORA_SX1276) += lora-sx1276.o
 lora-sx1276-y := sx1276.o
 
+obj-$(CONFIG_LORA_SX1301) += lora-sx1301.o
+lora-sx1301-y := sx1301.o
+
 obj-$(CONFIG_LORA_USI) += lora-usi.o
 lora-usi-y := usi.o
 
diff --git a/drivers/net/lora/sx1301.c b/drivers/net/lora/sx1301.c
new file mode 100644
index 000000000000..5c936c1116d1
--- /dev/null
+++ b/drivers/net/lora/sx1301.c
@@ -0,0 +1,446 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Semtech SX1301 LoRa concentrator
+ *
+ * Copyright (c) 2018 Andreas Färber
+ *
+ * Based on SX1301 HAL code:
+ * Copyright (c) 2013 Semtech-Cycleo
+ */
+
+#include <linux/bitops.h>
+#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_PAGE_RESET			0
+#define REG_VERSION			1
+#define REG_2_SPI_RADIO_A_DATA		33
+#define REG_2_SPI_RADIO_A_DATA_READBACK	34
+#define REG_2_SPI_RADIO_A_ADDR		35
+#define REG_2_SPI_RADIO_A_CS		37
+#define REG_2_SPI_RADIO_B_DATA		38
+#define REG_2_SPI_RADIO_B_DATA_READBACK	39
+#define REG_2_SPI_RADIO_B_ADDR		40
+#define REG_2_SPI_RADIO_B_CS		42
+
+#define REG_PAGE_RESET_SOFT_RESET	BIT(7)
+
+#define REG_16_GLOBAL_EN		BIT(3)
+
+#define REG_17_CLK32M_EN		BIT(0)
+
+#define REG_2_43_RADIO_A_EN		BIT(0)
+#define REG_2_43_RADIO_B_EN		BIT(1)
+#define REG_2_43_RADIO_RST		BIT(2)
+
+struct spi_sx1301 {
+	struct spi_device *parent;
+	u8 page;
+	u8 regs;
+};
+
+struct sx1301_priv {
+	struct lora_priv lora;
+	struct gpio_desc *rst_gpio;
+	u8 cur_page;
+	struct spi_controller *radio_a_ctrl, *radio_b_ctrl;
+};
+
+static int sx1301_read(struct spi_device *spi, u8 reg, u8 *val)
+{
+	u8 addr = reg & 0x7f;
+	return spi_write_then_read(spi, &addr, 1, val, 1);
+}
+
+static int sx1301_write(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 sx1301_page_switch(struct spi_device *spi, u8 page)
+{
+	struct sx1301_priv *priv = spi_get_drvdata(spi);
+	int ret;
+
+	if (priv->cur_page == page)
+		return 0;
+
+	dev_dbg(&spi->dev, "switching to page %u\n", (unsigned)page);
+	ret = sx1301_write(spi, REG_PAGE_RESET, page & 0x3);
+	if (ret) {
+		dev_err(&spi->dev, "switching to page %u failed\n", (unsigned)page);
+		return ret;
+	}
+
+	priv->cur_page = page;
+
+	return 0;
+}
+
+static int sx1301_soft_reset(struct spi_device *spi)
+{
+	return sx1301_write(spi, REG_PAGE_RESET, REG_PAGE_RESET_SOFT_RESET);
+}
+
+#define REG_RADIO_X_DATA		0
+#define REG_RADIO_X_DATA_READBACK	1
+#define REG_RADIO_X_ADDR		2
+#define REG_RADIO_X_CS			4
+
+static int sx1301_radio_set_cs(struct spi_controller *ctrl, bool enable)
+{
+	struct spi_sx1301 *ssx = spi_controller_get_devdata(ctrl);
+	u8 cs;
+	int ret;
+
+	dev_dbg(&ctrl->dev, "setting CS to %s\n", enable ? "1" : "0");
+
+	ret = sx1301_page_switch(ssx->parent, ssx->page);
+	if (ret) {
+		dev_warn(&ctrl->dev, "failed to switch page for CS (%d)\n", ret);
+		return ret;
+	}
+
+	ret = sx1301_read(ssx->parent, ssx->regs + REG_RADIO_X_CS, &cs);
+	if (ret) {
+		dev_warn(&ctrl->dev, "failed to read CS (%d)\n", ret);
+		cs = 0;
+	}
+
+	if (enable)
+		cs |= BIT(0);
+	else
+		cs &= ~BIT(0);
+
+	ret = sx1301_write(ssx->parent, ssx->regs + REG_RADIO_X_CS, cs);
+	if (ret)
+		dev_warn(&ctrl->dev, "failed to write CS (%d)\n", ret);
+
+	return 0;
+}
+
+static void sx1301_radio_spi_set_cs(struct spi_device *spi, bool enable)
+{
+	int ret;
+
+	dev_dbg(&spi->dev, "setting SPI CS to %s\n", enable ? "1" : "0");
+
+	if (enable)
+		return;
+
+	ret = sx1301_radio_set_cs(spi->controller, enable);
+	if (ret)
+		dev_warn(&spi->dev, "failed to write CS (%d)\n", ret);
+}
+
+static int sx1301_radio_spi_transfer_one(struct spi_controller *ctrl,
+	struct spi_device *spi, struct spi_transfer *xfr)
+{
+	struct spi_sx1301 *ssx = spi_controller_get_devdata(ctrl);
+	const u8 *tx_buf = xfr->tx_buf;
+	u8 *rx_buf = xfr->rx_buf;
+	int ret;
+
+	if (xfr->len == 0 || xfr->len > 3)
+		return -EINVAL;
+
+	dev_dbg(&spi->dev, "transferring one (%u)\n", xfr->len);
+
+	ret = sx1301_page_switch(ssx->parent, ssx->page);
+	if (ret) {
+		dev_err(&spi->dev, "failed to switch page for transfer (%d)\n", ret);
+		return ret;
+	}
+
+	if (tx_buf) {
+		ret = sx1301_write(ssx->parent, ssx->regs + REG_RADIO_X_ADDR, tx_buf ? tx_buf[0] : 0);
+		if (ret) {
+			dev_err(&spi->dev, "SPI radio address write failed\n");
+			return ret;
+		}
+
+		ret = sx1301_write(ssx->parent, ssx->regs + REG_RADIO_X_DATA, (tx_buf && xfr->len >= 2) ? tx_buf[1] : 0);
+		if (ret) {
+			dev_err(&spi->dev, "SPI radio data write failed\n");
+			return ret;
+		}
+
+		ret = sx1301_radio_set_cs(ctrl, true);
+		if (ret) {
+			dev_err(&spi->dev, "SPI radio CS set failed\n");
+			return ret;
+		}
+
+		ret = sx1301_radio_set_cs(ctrl, false);
+		if (ret) {
+			dev_err(&spi->dev, "SPI radio CS unset failed\n");
+			return ret;
+		}
+	}
+
+	if (rx_buf) {
+		ret = sx1301_read(ssx->parent, ssx->regs + REG_RADIO_X_DATA_READBACK, &rx_buf[xfr->len - 1]);
+		if (ret) {
+			dev_err(&spi->dev, "SPI radio data read failed\n");
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static void sx1301_radio_setup(struct spi_controller *ctrl)
+{
+	ctrl->mode_bits = SPI_CS_HIGH | SPI_NO_CS;
+	ctrl->bits_per_word_mask = SPI_BPW_MASK(8);
+	ctrl->num_chipselect = 1;
+	ctrl->set_cs = sx1301_radio_spi_set_cs;
+	ctrl->transfer_one = sx1301_radio_spi_transfer_one;
+}
+
+static int sx1301_probe(struct spi_device *spi)
+{
+	struct net_device *netdev;
+	struct sx1301_priv *priv;
+	struct spi_sx1301 *radio;
+	struct gpio_desc *rst;
+	int ret;
+	u8 val;
+
+	rst = devm_gpiod_get_optional(&spi->dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(rst))
+		return PTR_ERR(rst);
+
+	gpiod_set_value_cansleep(rst, 1);
+	msleep(100);
+	gpiod_set_value_cansleep(rst, 0);
+	msleep(100);
+
+	spi->bits_per_word = 8;
+	spi_setup(spi);
+
+	ret = sx1301_read(spi, REG_VERSION, &val);
+	if (ret) {
+		dev_err(&spi->dev, "version read failed\n");
+		goto err_version;
+	}
+
+	if (val != 103) {
+		dev_err(&spi->dev, "unexpected version: %u\n", val);
+		ret = -ENXIO;
+		goto err_version;
+	}
+
+	netdev = alloc_loradev(sizeof(*priv));
+	if (!netdev) {
+		ret = -ENOMEM;
+		goto err_alloc_loradev;
+	}
+
+	priv = netdev_priv(netdev);
+	priv->rst_gpio = rst;
+	priv->cur_page = 0xff;
+
+	spi_set_drvdata(spi, netdev);
+	SET_NETDEV_DEV(netdev, &spi->dev);
+
+	ret = sx1301_write(spi, REG_PAGE_RESET, 0);
+	if (ret) {
+		dev_err(&spi->dev, "page/reset write failed\n");
+		return ret;
+	}
+
+	ret = sx1301_soft_reset(spi);
+	if (ret) {
+		dev_err(&spi->dev, "soft reset failed\n");
+		return ret;
+	}
+
+	ret = sx1301_read(spi, 16, &val);
+	if (ret) {
+		dev_err(&spi->dev, "16 read failed\n");
+		return ret;
+	}
+
+	val &= ~REG_16_GLOBAL_EN;
+
+	ret = sx1301_write(spi, 16, val);
+	if (ret) {
+		dev_err(&spi->dev, "16 write failed\n");
+		return ret;
+	}
+
+	ret = sx1301_read(spi, 17, &val);
+	if (ret) {
+		dev_err(&spi->dev, "17 read failed\n");
+		return ret;
+	}
+
+	val &= ~REG_17_CLK32M_EN;
+
+	ret = sx1301_write(spi, 17, val);
+	if (ret) {
+		dev_err(&spi->dev, "17 write failed\n");
+		return ret;
+	}
+
+	ret = sx1301_page_switch(spi, 2);
+	if (ret) {
+		dev_err(&spi->dev, "page 2 switch failed\n");
+		return ret;
+	}
+
+	ret = sx1301_read(spi, 43, &val);
+	if (ret) {
+		dev_err(&spi->dev, "2|43 read failed\n");
+		return ret;
+	}
+
+	val |= REG_2_43_RADIO_B_EN | REG_2_43_RADIO_A_EN;
+
+	ret = sx1301_write(spi, 43, val);
+	if (ret) {
+		dev_err(&spi->dev, "2|43 write failed\n");
+		return ret;
+	}
+
+	msleep(500);
+
+	ret = sx1301_read(spi, 43, &val);
+	if (ret) {
+		dev_err(&spi->dev, "2|43 read failed\n");
+		return ret;
+	}
+
+	val |= REG_2_43_RADIO_RST;
+
+	ret = sx1301_write(spi, 43, val);
+	if (ret) {
+		dev_err(&spi->dev, "2|43 write failed\n");
+		return ret;
+	}
+
+	msleep(5);
+
+	ret = sx1301_read(spi, 43, &val);
+	if (ret) {
+		dev_err(&spi->dev, "2|43 read failed\n");
+		return ret;
+	}
+
+	val &= ~REG_2_43_RADIO_RST;
+
+	ret = sx1301_write(spi, 43, val);
+	if (ret) {
+		dev_err(&spi->dev, "2|43 write failed\n");
+		return ret;
+	}
+
+	/* radio A */
+
+	priv->radio_a_ctrl = spi_alloc_master(&spi->dev, sizeof(*radio));
+	if (!priv->radio_a_ctrl) {
+		ret = -ENOMEM;
+		goto err_radio_a_alloc;
+	}
+
+	sx1301_radio_setup(priv->radio_a_ctrl);
+	priv->radio_a_ctrl->dev.of_node = of_get_child_by_name(spi->dev.of_node, "radio-a");
+
+	radio = spi_controller_get_devdata(priv->radio_a_ctrl);
+	radio->page = 2;
+	radio->regs = REG_2_SPI_RADIO_A_DATA;
+	radio->parent = spi;
+
+	dev_info(&spi->dev, "registering radio A SPI\n");
+
+	ret = devm_spi_register_controller(&spi->dev, priv->radio_a_ctrl);
+	if (ret) {
+		dev_err(&spi->dev, "radio A SPI register failed\n");
+		goto err_radio_a_register;
+	}
+
+	/* radio B */
+
+	priv->radio_b_ctrl = spi_alloc_master(&spi->dev, sizeof(*radio));
+	if (!priv->radio_b_ctrl) {
+		ret = -ENOMEM;
+		goto err_radio_b_alloc;
+	}
+
+	sx1301_radio_setup(priv->radio_b_ctrl);
+	priv->radio_b_ctrl->dev.of_node = of_get_child_by_name(spi->dev.of_node, "radio-b");
+
+	radio = spi_controller_get_devdata(priv->radio_b_ctrl);
+	radio->page = 2;
+	radio->regs = REG_2_SPI_RADIO_B_DATA;
+	radio->parent = spi;
+
+	dev_info(&spi->dev, "registering radio B SPI\n");
+
+	ret = devm_spi_register_controller(&spi->dev, priv->radio_b_ctrl);
+	if (ret) {
+		dev_err(&spi->dev, "radio B SPI register failed\n");
+		goto err_radio_b_register;
+	}
+
+	dev_info(&spi->dev, "SX1301 module probed\n");
+
+	return 0;
+err_radio_b_register:
+	spi_controller_put(priv->radio_b_ctrl);
+err_radio_b_alloc:
+err_radio_a_register:
+	spi_controller_put(priv->radio_a_ctrl);
+err_radio_a_alloc:
+	free_loradev(netdev);
+err_alloc_loradev:
+err_version:
+	return ret;
+}
+
+static int sx1301_remove(struct spi_device *spi)
+{
+	struct net_device *netdev = spi_get_drvdata(spi);
+
+	//unregister_loradev(netdev);
+	free_loradev(netdev);
+
+	dev_info(&spi->dev, "SX1301 module removed\n");
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id sx1301_dt_ids[] = {
+	{ .compatible = "semtech,sx1301" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, sx1301_dt_ids);
+#endif
+
+static struct spi_driver sx1301_spi_driver = {
+	.driver = {
+		.name = "sx1301",
+		.of_match_table = of_match_ptr(sx1301_dt_ids),
+	},
+	.probe = sx1301_probe,
+	.remove = sx1301_remove,
+};
+
+module_spi_driver(sx1301_spi_driver);
+
+MODULE_DESCRIPTION("SX1301 SPI driver");
+MODULE_AUTHOR("Andreas Färber <afaerber@suse.de>");
+MODULE_LICENSE("GPL");
-- 
2.16.4