[PATCH v6 07/24] wfx: add bus_spi.c

[Jerome Pouiller <Jerome.Pouiller@silabs.com>]

From: Jérôme Pouiller <jerome.pouiller@silabs.com>

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
---
 drivers/net/wireless/silabs/wfx/bus_spi.c | 271 ++++++++++++++++++++++
 1 file changed, 271 insertions(+)
 create mode 100644 drivers/net/wireless/silabs/wfx/bus_spi.c

diff --git a/drivers/net/wireless/silabs/wfx/bus_spi.c b/drivers/net/wireless/silabs/wfx/bus_spi.c
new file mode 100644
index 000000000000..55ffcd7c42e2
--- /dev/null
+++ b/drivers/net/wireless/silabs/wfx/bus_spi.c
@@ -0,0 +1,271 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * SPI interface.
+ *
+ * Copyright (c) 2017-2020, Silicon Laboratories, Inc.
+ * Copyright (c) 2011, Sagrad Inc.
+ * Copyright (c) 2010, ST-Ericsson
+ */
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/spi/spi.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/of.h>
+
+#include "bus.h"
+#include "wfx.h"
+#include "hwio.h"
+#include "main.h"
+#include "bh.h"
+
+#define SET_WRITE 0x7FFF        /* usage: and operation */
+#define SET_READ 0x8000         /* usage: or operation */
+
+#define WFX_RESET_INVERTED 1
+
+static const struct wfx_platform_data wfx_spi_pdata = {
+	.file_fw = "wfm_wf200",
+	.file_pds = "wf200.pds",
+	.use_rising_clk = true,
+};
+
+struct wfx_spi_priv {
+	struct spi_device *func;
+	struct wfx_dev *core;
+	struct gpio_desc *gpio_reset;
+	bool need_swab;
+};
+
+/* The chip reads 16bits of data at time and place them directly into (little
+ * endian) CPU register. So, the chip expects bytes order to be "B1 B0 B3 B2"
+ * (while LE is "B0 B1 B2 B3" and BE is "B3 B2 B1 B0")
+ *
+ * A little endian host with bits_per_word == 16 should do the right job
+ * natively. The code below to support big endian host and commonly used SPI
+ * 8bits.
+ */
+static int wfx_spi_copy_from_io(void *priv, unsigned int addr,
+				void *dst, size_t count)
+{
+	struct wfx_spi_priv *bus = priv;
+	u16 regaddr = (addr << 12) | (count / 2) | SET_READ;
+	struct spi_message      m;
+	struct spi_transfer     t_addr = {
+		.tx_buf         = &regaddr,
+		.len            = sizeof(regaddr),
+	};
+	struct spi_transfer     t_msg = {
+		.rx_buf         = dst,
+		.len            = count,
+	};
+	u16 *dst16 = dst;
+	int ret, i;
+
+	WARN(count % 2, "buffer size must be a multiple of 2");
+
+	cpu_to_le16s(&regaddr);
+	if (bus->need_swab)
+		swab16s(&regaddr);
+
+	spi_message_init(&m);
+	spi_message_add_tail(&t_addr, &m);
+	spi_message_add_tail(&t_msg, &m);
+	ret = spi_sync(bus->func, &m);
+
+	if (bus->need_swab && addr == WFX_REG_CONFIG)
+		for (i = 0; i < count / 2; i++)
+			swab16s(&dst16[i]);
+	return ret;
+}
+
+static int wfx_spi_copy_to_io(void *priv, unsigned int addr,
+			      const void *src, size_t count)
+{
+	struct wfx_spi_priv *bus = priv;
+	u16 regaddr = (addr << 12) | (count / 2);
+	/* FIXME: use a bounce buffer */
+	u16 *src16 = (void *)src;
+	int ret, i;
+	struct spi_message      m;
+	struct spi_transfer     t_addr = {
+		.tx_buf         = &regaddr,
+		.len            = sizeof(regaddr),
+	};
+	struct spi_transfer     t_msg = {
+		.tx_buf         = src,
+		.len            = count,
+	};
+
+	WARN(count % 2, "buffer size must be a multiple of 2");
+	WARN(regaddr & SET_READ, "bad addr or size overflow");
+
+	cpu_to_le16s(&regaddr);
+
+	/* Register address and CONFIG content always use 16bit big endian
+	 * ("BADC" order)
+	 */
+	if (bus->need_swab)
+		swab16s(&regaddr);
+	if (bus->need_swab && addr == WFX_REG_CONFIG)
+		for (i = 0; i < count / 2; i++)
+			swab16s(&src16[i]);
+
+	spi_message_init(&m);
+	spi_message_add_tail(&t_addr, &m);
+	spi_message_add_tail(&t_msg, &m);
+	ret = spi_sync(bus->func, &m);
+
+	if (bus->need_swab && addr == WFX_REG_CONFIG)
+		for (i = 0; i < count / 2; i++)
+			swab16s(&src16[i]);
+	return ret;
+}
+
+static void wfx_spi_lock(void *priv)
+{
+}
+
+static void wfx_spi_unlock(void *priv)
+{
+}
+
+static irqreturn_t wfx_spi_irq_handler(int irq, void *priv)
+{
+	struct wfx_spi_priv *bus = priv;
+
+	wfx_bh_request_rx(bus->core);
+	return IRQ_HANDLED;
+}
+
+static int wfx_spi_irq_subscribe(void *priv)
+{
+	struct wfx_spi_priv *bus = priv;
+	u32 flags;
+
+	flags = irq_get_trigger_type(bus->func->irq);
+	if (!flags)
+		flags = IRQF_TRIGGER_HIGH;
+	flags |= IRQF_ONESHOT;
+	return devm_request_threaded_irq(&bus->func->dev, bus->func->irq, NULL,
+					 wfx_spi_irq_handler, IRQF_ONESHOT,
+					 "wfx", bus);
+}
+
+static int wfx_spi_irq_unsubscribe(void *priv)
+{
+	struct wfx_spi_priv *bus = priv;
+
+	devm_free_irq(&bus->func->dev, bus->func->irq, bus);
+	return 0;
+}
+
+static size_t wfx_spi_align_size(void *priv, size_t size)
+{
+	/* Most of SPI controllers avoid DMA if buffer size is not 32bit aligned
+	 */
+	return ALIGN(size, 4);
+}
+
+static const struct hwbus_ops wfx_spi_hwbus_ops = {
+	.copy_from_io = wfx_spi_copy_from_io,
+	.copy_to_io = wfx_spi_copy_to_io,
+	.irq_subscribe = wfx_spi_irq_subscribe,
+	.irq_unsubscribe = wfx_spi_irq_unsubscribe,
+	.lock			= wfx_spi_lock,
+	.unlock			= wfx_spi_unlock,
+	.align_size		= wfx_spi_align_size,
+};
+
+static int wfx_spi_probe(struct spi_device *func)
+{
+	struct wfx_spi_priv *bus;
+	int ret;
+
+	if (!func->bits_per_word)
+		func->bits_per_word = 16;
+	ret = spi_setup(func);
+	if (ret)
+		return ret;
+	/* Trace below is also displayed by spi_setup() if compiled with DEBUG */
+	dev_dbg(&func->dev, "SPI params: CS=%d, mode=%d bits/word=%d speed=%d\n",
+		func->chip_select, func->mode, func->bits_per_word,
+		func->max_speed_hz);
+	if (func->bits_per_word != 16 && func->bits_per_word != 8)
+		dev_warn(&func->dev, "unusual bits/word value: %d\n",
+			 func->bits_per_word);
+	if (func->max_speed_hz > 50000000)
+		dev_warn(&func->dev, "%dHz is a very high speed\n",
+			 func->max_speed_hz);
+
+	bus = devm_kzalloc(&func->dev, sizeof(*bus), GFP_KERNEL);
+	if (!bus)
+		return -ENOMEM;
+	bus->func = func;
+	if (func->bits_per_word == 8 || IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
+		bus->need_swab = true;
+	spi_set_drvdata(func, bus);
+
+	bus->gpio_reset = devm_gpiod_get_optional(&func->dev, "reset",
+						  GPIOD_OUT_LOW);
+	if (IS_ERR(bus->gpio_reset))
+		return PTR_ERR(bus->gpio_reset);
+	if (!bus->gpio_reset) {
+		dev_warn(&func->dev,
+			 "gpio reset is not defined, trying to load firmware anyway\n");
+	} else {
+		gpiod_set_consumer_name(bus->gpio_reset, "wfx reset");
+		if (spi_get_device_id(func)->driver_data & WFX_RESET_INVERTED)
+			gpiod_toggle_active_low(bus->gpio_reset);
+		gpiod_set_value_cansleep(bus->gpio_reset, 1);
+		usleep_range(100, 150);
+		gpiod_set_value_cansleep(bus->gpio_reset, 0);
+		usleep_range(2000, 2500);
+	}
+
+	bus->core = wfx_init_common(&func->dev, &wfx_spi_pdata,
+				    &wfx_spi_hwbus_ops, bus);
+	if (!bus->core)
+		return -EIO;
+
+	return wfx_probe(bus->core);
+}
+
+static int wfx_spi_remove(struct spi_device *func)
+{
+	struct wfx_spi_priv *bus = spi_get_drvdata(func);
+
+	wfx_release(bus->core);
+	return 0;
+}
+
+/* For dynamic driver binding, kernel does not use OF to match driver. It only
+ * use modalias and modalias is a copy of 'compatible' DT node with vendor
+ * stripped.
+ */
+static const struct spi_device_id wfx_spi_id[] = {
+	{ "wfx-spi", WFX_RESET_INVERTED },
+	{ "wf200", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(spi, wfx_spi_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id wfx_spi_of_match[] = {
+	{ .compatible = "silabs,wfx-spi", .data = (void *)WFX_RESET_INVERTED },
+	{ .compatible = "silabs,wf200" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, wfx_spi_of_match);
+#endif
+
+struct spi_driver wfx_spi_driver = {
+	.driver = {
+		.name = "wfx-spi",
+		.of_match_table = of_match_ptr(wfx_spi_of_match),
+	},
+	.id_table = wfx_spi_id,
+	.probe = wfx_spi_probe,
+	.remove = wfx_spi_remove,
+};
-- 
2.33.0