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, 8 insertions, 0 deletions

diff --git a/drivers/staging/wfx/Makefile b/drivers/staging/wfx/Makefile
new file mode 100644
index 000000000000..74939a5a0a1c
--- /dev/null
+++ b/drivers/staging/wfx/Makefile
@@ -0,0 +1,8 @@
+# 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