nfc: add configuration for out of tree build

The nfc and ese drivers are built as modules
fixes for st21nfc.c are required to build it on LLVM

Bug: 168350321
Signed-off-by: Alisher Alikhodjaev <alisher@google.com>
Change-Id: Ifa88b8e243de20c6afda8a1350a4c79c417df4cf

3 files changed, 48 insertions, 2 deletions

diff --git a/Kconfig b/Kconfig
new file mode 100644
index 0000000..b1ca6c3
--- /dev/null
+++ b/Kconfig
@@ -0,0 +1,28 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Near Field Communication (NFC) devices
+#
+
+config NFC_ST21NFC
+	tristate "ST Microelectronics ST21NFC NFC Controller Driver"
+	depends on I2C
+	help
+	 ST Microelectronics ST21NFC Near Field Communication controller support.
+
+config NFC_ST21NFC_NO_CRYSTAL
+	bool "ST Microelectronics ST21NFC NFC Controller Driver, no external crystal"
+	depends on NFC_ST21NFC
+	help
+	 ST Microelectronics ST21NFC Near Field Communication controller support.
+
+config ESE_ST54
+	tristate "ST Microelectronics ST54 family ESE driver"
+	depends on SPI
+	help
+	  ST Microelectronics ST54 ESE Near Field Communication controller support.
+
+config ESE_ST33
+	tristate "ST Microelectronics ST33 ESE driver"
+	depends on SPI
+	help
+	  ST Microelectronics ST33 ESE Near Field Communication controller support.
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..8ffee38
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for nfc devices
+#
+
+obj-$(CONFIG_NFC_ST21NFC)	+= st21nfc.o
+obj-$(CONFIG_ESE_ST54)		+= ese/
+
+KERNEL_SRC ?= /lib/modules/$(shell uname -r)/build
+M ?= $(shell pwd)
+
+KBUILD_OPTIONS += CONFIG_NFC_ST21NFC=m CONFIG_NFC_ST21NFC_NO_CRYSTAL=y \
+		  CONFIG_ESE_ST54=m CONFIG_ESE_ST33=m
+
+ccflags-y := -I$(KERNEL_SRC)/../google-modules/nfc
+
+modules modules_install clean:
+	$(MAKE) -C $(KERNEL_SRC) M=$(M) $(KBUILD_OPTIONS) W=1 $(@)
diff --git a/st21nfc.c b/st21nfc.c
index d2632ba..d97665c 100644
--- a/st21nfc.c
+++ b/st21nfc.c
@@ -359,7 +359,7 @@ static void st21nfc_power_stats_idle_signal(struct st21nfc_device *st21nfc_dev)
 	}
 }
 
-void st21nfc_pstate_wq(struct work_struct *work)
+static void st21nfc_pstate_wq(struct work_struct *work)
 {
 	struct st21nfc_device *st21nfc_dev = container_of(work,
 							struct st21nfc_device,
@@ -395,7 +395,7 @@ static void st21nfc_power_stats_filter(
 
 	if (count != HEADER_LENGTH) {
 		dev_err(&st21nfc_dev->client->dev,
-			"%s Warning: expect previous one was idle data\n");
+			"Warning: expect previous one was idle data\n");
 		st21nfc_dev->pw_states_err.header_payload++;
 		return;
 	}