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.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 70 insertions, 0 deletions

diff --git a/drivers/staging/wfx/bus_sdio.c b/drivers/staging/wfx/bus_sdio.c
new file mode 100644
index 000000000000..4b26c994f43c
--- /dev/null
+++ b/drivers/staging/wfx/bus_sdio.c
@@ -0,0 +1,70 @@
+// 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),
+	}
+};