staging: wfx: add infrastructure for new driver

Instantiate build infrastructure WFx driver. This driver provides support
for Wifi chipset Silicon Labs WF200 and further:

   https://www.silabs.com/documents/public/data-sheets/wf200-datasheet.pdf

This chip support SPI and SDIO bus.

SDIO interface has two particularities:
    1. Some parameters may be useful for end user (I will talk about
       gpio_wakeup later).
    2. The SDIO VID and PID of WF200 are 0000:0001 which are too much
       generic to rely on.

So, current code checks VID/PID and looks for a node in DT (since WF200
targets embedded platforms, I don't think it is a problem to rely on
DT). DT can also be used to define to parameters for driver. Currently,
if no node is found, a warning is emitted, but it could be changed in
error.
Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20190919142527.31797-2-Jerome.Pouiller@silabs.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

MAINTAINERS

@@ -14802,6 +14802,11 @@ S:	Maintained
 F:	drivers/input/touchscreen/silead.c
 F:	drivers/platform/x86/touchscreen_dmi.c
 
+SILICON LABS WIRELESS DRIVERS (for WFxxx series)
+M:	Jérôme Pouiller <jerome.pouiller@silabs.com>
+S:	Supported
+F:	drivers/staging/wfx/
+
 SILICON MOTION SM712 FRAME BUFFER DRIVER
 M:	Sudip Mukherjee <sudipm.mukherjee@gmail.com>
 M:	Teddy Wang <teddy.wang@siliconmotion.com>

drivers/staging/Kconfig

@@ -125,4 +125,6 @@ source "drivers/staging/exfat/Kconfig"
 
 source "drivers/staging/qlge/Kconfig"
 
+source "drivers/staging/wfx/Kconfig"
+
 endif # STAGING

drivers/staging/Makefile

@@ -53,3 +53,4 @@ obj-$(CONFIG_UWB)		+= uwb/
 obj-$(CONFIG_USB_WUSB)		+= wusbcore/
 obj-$(CONFIG_EXFAT_FS)		+= exfat/
 obj-$(CONFIG_QLGE)		+= qlge/
+obj-$(CONFIG_WFX)		+= wfx/

drivers/staging/wfx/Documentation/devicetree/bindings/net/wireless/siliabs,wfx.txt

+The WFxxx chip series can be connected via SPI or via SDIO.
+
+SPI
+---
+
+You have to declare the WFxxx chip in your device tree.
+
+Required properties:
+ - compatible: Should be "silabs,wfx-spi"
+ - reg: Chip select address of device
+ - spi-max-frequency: Maximum SPI clocking speed of device in Hz
+ - interrupts-extended: Should contain interrupt line (interrupt-parent +
+   interrupt can also been used). Trigger should be `IRQ_TYPE_EDGE_RISING`.
+
+Optional properties:
+ - reset-gpios: phandle of gpio that will be used to reset chip during probe.
+   Without this property, you may encounter issues with warm boot.
+
+Please consult Documentation/devicetree/bindings/spi/spi-bus.txt for optional
+SPI connection related properties,
+
+Example:
+
+&spi1 {
+	wfx {
+		compatible = "silabs,wfx-spi";
+		pinctrl-names = "default";
+		pinctrl-0 = <&wfx_irq &wfx_gpios>;
+		interrupts-extended = <&gpio 16 IRQ_TYPE_EDGE_RISING>;
+		wakeup-gpios = <&gpio 12 GPIO_ACTIVE_HIGH>;
+		reset-gpios = <&gpio 13 GPIO_ACTIVE_HIGH>;
+		reg = <0>;
+		spi-max-frequency = <42000000>;
+	};
+};
+
+
+SDIO
+----
+
+The driver is able to detect a WFxxx chip on SDIO bus by matching its Vendor ID
+and Product ID. However, driver will only provide limited features in this
+case. Thus declaring WFxxx chip in device tree is strongly recommended (and may
+become mandatory in the future).
+
+Required properties:
+ - compatible: Should be "silabs,wfx-sdio"
+ - reg: Should be 1
+
+In addition, it is recommended to declare a mmc-pwrseq on SDIO host above WFx.
+Without it, you may encounter issues with warm boot. mmc-pwrseq should be
+compatible with mmc-pwrseq-simple. Please consult
+Documentation/devicetree/bindings/mmc/mmc-pwrseq-simple.txt for more
+information.
+
+Example:
+
+/ {
+	wfx_pwrseq: wfx_pwrseq {
+		compatible = "mmc-pwrseq-simple";
+		pinctrl-names = "default";
+		pinctrl-0 = <&wfx_reset>;
+		reset-gpios = <&gpio 13 GPIO_ACTIVE_LOW>;
+	};
+};
+
+&mmc1 {
+	mmc-pwrseq = <&wfx_pwrseq>;
+	#address-size = <1>;
+	#size = <0>;
+
+	mmc@1 {
+		compatible = "silabs,wfx-sdio";
+		reg = <1>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&wfx_wakeup>;
+		wakeup-gpios = <&gpio 12 GPIO_ACTIVE_HIGH>;
+	};
+};
+
+Note that #address-size and #size shoud already be defined in node mmc1, but it
+is rarely the case.
+
+Common properties
+-----------------
+
+Some properties are recognized either by SPI and SDIO versions:
+ - wakeup-gpios: phandle of gpio that will be used to wake-up chip. Without
+   this property, driver will disable most of power saving features.
+ - config-file: Use an alternative file as PDS. Default is `wf200.pds`. Only
+   necessary for development/debug purpose.
+ - slk_key: String representing hexdecimal value of secure link key to use.
+   Must contains 64 hexadecimal digits. Not supported in current version.
+
+WFx driver also supports `mac-address` and `local-mac-address` as described in
+Documentation/devicetree/binding/net/ethernet.txt
+

drivers/staging/wfx/Kconfig

+config WFX
+	tristate "Silicon Labs wireless chips WF200 and further"
+	depends on MAC80211
+	depends on (SPI || MMC)
+	help
+	  This is a driver for Silicons Labs WFxxx series (WF200 and further)
+	  chipsets. This chip can be found on SPI or SDIO buses.

drivers/staging/wfx/Makefile

+# SPDX-License-Identifier: GPL-2.0
+
+wfx-y := \
+	main.o
+wfx-$(CONFIG_SPI) += bus_spi.o
+wfx-$(subst m,y,$(CONFIG_MMC)) += bus_sdio.o
+
+obj-$(CONFIG_WFX) += wfx.o

drivers/staging/wfx/TODO

+This is a list of things that need to be done to get this driver out of the
+staging directory.
+
+  - wfx_version.h is still there in order to ensure synchronization with github.
+    It can be dropped as soon as development is entirely in kernel
+
+  - I have to take a decision about secure link support. I can:
+      - drop completely
+      - keep it in an external patch (my preferred option)
+      - replace call to mbedtls with kernel crypto API (necessitate a
+        bunch of work)
+      - pull mbedtls in kernel (non-realistic)
+
+  - mac80211 interface does not (yet) have expected quality to be placed
+    outside of staging:
+      - Some processings are redundant with mac80211 ones
+      - Many members from wfx_dev/wfx_vif can be retrieved from mac80211
+        structures
+      - Some functions are too complex
+      - ...

drivers/staging/wfx/bus.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Common bus abstraction layer.
+ *
+ * Copyright (c) 2017-2018, Silicon Laboratories, Inc.
+ * Copyright (c) 2010, ST-Ericsson
+ */
+#ifndef WFX_BUS_H
+#define WFX_BUS_H
+
+#include <linux/mmc/sdio_func.h>
+#include <linux/spi/spi.h>
+
+extern struct sdio_driver wfx_sdio_driver;
+extern struct spi_driver wfx_spi_driver;
+
+#endif

drivers/staging/wfx/bus_sdio.c

+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * SDIO interface.
+ *
+ * Copyright (c) 2017-2019, Silicon Laboratories, Inc.
+ * Copyright (c) 2010, ST-Ericsson
+ */
+#include <linux/module.h>
+#include <linux/mmc/sdio_func.h>
+#include <linux/mmc/card.h>
+#include <linux/of_irq.h>
+
+#include "bus.h"
+
+static const struct of_device_id wfx_sdio_of_match[];
+static int wfx_sdio_probe(struct sdio_func *func,
+			  const struct sdio_device_id *id)
+{
+	struct device_node *np = func->dev.of_node;
+
+	if (func->num != 1) {
+		dev_err(&func->dev, "SDIO function number is %d while it should always be 1 (unsupported chip?)\n", func->num);
+		return -ENODEV;
+	}
+
+	if (np) {
+		if (!of_match_node(wfx_sdio_of_match, np)) {
+			dev_warn(&func->dev, "no compatible device found in DT\n");
+			return -ENODEV;
+		}
+	} else {
+		dev_warn(&func->dev, "device is not declared in DT, features will be limited\n");
+		// FIXME: ignore VID/PID and only rely on device tree
+		// return -ENODEV;
+	}
+	return -EIO; // FIXME: not yet supported
+}
+
+static void wfx_sdio_remove(struct sdio_func *func)
+{
+}
+
+#define SDIO_VENDOR_ID_SILABS        0x0000
+#define SDIO_DEVICE_ID_SILABS_WF200  0x1000
+static const struct sdio_device_id wfx_sdio_ids[] = {
+	{ SDIO_DEVICE(SDIO_VENDOR_ID_SILABS, SDIO_DEVICE_ID_SILABS_WF200) },
+	// FIXME: ignore VID/PID and only rely on device tree
+	// { SDIO_DEVICE(SDIO_ANY_ID, SDIO_ANY_ID) },
+	{ },
+};
+MODULE_DEVICE_TABLE(sdio, wfx_sdio_ids);
+
+#ifdef CONFIG_OF
+static const struct of_device_id wfx_sdio_of_match[] = {
+	{ .compatible = "silabs,wfx-sdio" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, wfx_sdio_of_match);
+#endif
+
+struct sdio_driver wfx_sdio_driver = {
+	.name = "wfx-sdio",
+	.id_table = wfx_sdio_ids,
+	.probe = wfx_sdio_probe,
+	.remove = wfx_sdio_remove,
+	.drv = {
+		.owner = THIS_MODULE,
+		.of_match_table = of_match_ptr(wfx_sdio_of_match),
+	}
+};

drivers/staging/wfx/bus_spi.c

+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * SPI interface.
+ *
+ * Copyright (c) 2017-2019, Silicon Laboratories, Inc.
+ * Copyright (c) 2011, Sagrad Inc.
+ * Copyright (c) 2010, ST-Ericsson
+ */
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+#include <linux/of.h>
+
+#include "bus.h"
+
+static int wfx_spi_probe(struct spi_device *func)
+{
+	return -EIO;
+}
+
+/* Disconnect Function to be called by SPI stack when device is disconnected */
+static int wfx_spi_disconnect(struct spi_device *func)
+{
+	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", 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" },
+	{ },
+};
+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_disconnect,
+};

drivers/staging/wfx/main.c

+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Device probe and register.
+ *
+ * Copyright (c) 2017-2019, Silicon Laboratories, Inc.
+ * Copyright (c) 2010, ST-Ericsson
+ * Copyright (c) 2008, Johannes Berg <johannes@sipsolutions.net>
+ * Copyright (c) 2008 Nokia Corporation and/or its subsidiary(-ies).
+ * Copyright (c) 2007-2009, Christian Lamparter <chunkeey@web.de>
+ * Copyright (c) 2006, Michael Wu <flamingice@sourmilk.net>
+ * Copyright (c) 2004-2006 Jean-Baptiste Note <jbnote@gmail.com>, et al.
+ */
+#include <linux/module.h>
+#include <linux/mmc/sdio_func.h>
+#include <linux/spi/spi.h>
+#include <linux/etherdevice.h>
+
+#include "bus.h"
+#include "wfx_version.h"
+
+MODULE_DESCRIPTION("Silicon Labs 802.11 Wireless LAN driver for WFx");
+MODULE_AUTHOR("Jérôme Pouiller <jerome.pouiller@silabs.com>");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(WFX_LABEL);
+
+static int __init wfx_core_init(void)
+{
+	int ret = 0;
+
+	pr_info("wfx: Silicon Labs " WFX_LABEL "\n");
+
+	if (IS_ENABLED(CONFIG_SPI))
+		ret = spi_register_driver(&wfx_spi_driver);
+	if (IS_ENABLED(CONFIG_MMC) && !ret)
+		ret = sdio_register_driver(&wfx_sdio_driver);
+	return ret;
+}
+module_init(wfx_core_init);
+
+static void __exit wfx_core_exit(void)
+{
+	if (IS_ENABLED(CONFIG_MMC))
+		sdio_unregister_driver(&wfx_sdio_driver);
+	if (IS_ENABLED(CONFIG_SPI))
+		spi_unregister_driver(&wfx_spi_driver);
+}
+module_exit(wfx_core_exit);

drivers/staging/wfx/wfx_version.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+/* THIS FILE IS AUTOMATICALLY GENERATED. DO NOT EDIT! */
+#define WFX_LABEL "2.3.1"