xpadneo, core: Add support for synthetic devices

In preparation for mouse mode and keyboard emulation, we need to be
able to create virtual devices associated with the controller.

Signed-off-by: Kai Krakow <[email protected]>

.gitignore

@@ -6,8 +6,8 @@ docs/_site/**
 docs/Gemfile.lock
 hid-xpadneo/dkms.conf
 hid-xpadneo/src/*.ko*
-hid-xpadneo/src/*.mod*
-hid-xpadneo/src/*.o*
+hid-xpadneo/**/*.mod*
+hid-xpadneo/**/*.o*
 hid-xpadneo/src/*.symvers*
 
 #FIXME(kakra) remove after source file split

hid-xpadneo/src/Makefile

@@ -8,3 +8,5 @@ obj-m += hid-xpadneo.o
 hid-xpadneo-y += xpadneo.o
 $(obj)/xpadneo.c: $(src)/hid-xpadneo.c
 	cp $< $@
+
+hid-xpadneo-y += xpadneo/core.o

hid-xpadneo/src/xpadneo.h

@@ -178,4 +178,6 @@ struct xpadneo_devdata {
 	void *output_report_dmabuf;
 };
 
+extern int xpadneo_init_synthetic(struct xpadneo_devdata *, char *, struct input_dev **);
+
 #endif

hid-xpadneo/src/xpadneo/core.c

@@ -0,0 +1,37 @@
+/*
+ * xpadneo driver core
+ *
+ * Copyright (c) 2021 Kai Krakow <[email protected]>
+ */
+
+#include "../xpadneo.h"
+
+extern int xpadneo_init_synthetic(struct xpadneo_devdata *xdata, char *suffix,
+				  struct input_dev **devp)
+{
+	struct hid_device *hdev = xdata->hdev;
+	struct input_dev *input_dev = devm_input_allocate_device(&hdev->dev);
+	size_t suffix_len, name_len;
+
+	if (!input_dev)
+		return -ENOMEM;
+
+	name_len = strlen(hdev->name);
+	suffix_len = strlen(suffix);
+	if ((name_len < suffix_len) || strcmp(xdata->hdev->name + name_len - suffix_len, suffix)) {
+		input_dev->name = kasprintf(GFP_KERNEL, "%s %s", hdev->name, suffix);
+		if (!input_dev->name)
+			return -ENOMEM;
+	}
+
+	dev_set_drvdata(&input_dev->dev, xdata);
+	input_dev->phys = hdev->phys;
+	input_dev->uniq = hdev->uniq;
+	input_dev->id.bustype = hdev->bus;
+	input_dev->id.vendor = hdev->vendor;
+	input_dev->id.product = hdev->product;
+	input_dev->id.version = hdev->version;
+
+	*devp = input_dev;
+	return 0;
+}