HID: wacom: Fix several minor compiler warnings

Addresses a few issues that were noticed when compiling with non-default
warnings enabled. The trimmed-down warnings in the order they are fixed
below are:

* declaration of 'size' shadows a parameter

* '%s' directive output may be truncated writing up to 5 bytes into a
  region of size between 1 and 64

* pointer targets in initialization of 'char *' from 'unsigned char *'
  differ in signedness

* left shift of negative value
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Reviewed-by: Aaron Armstrong Skomra <aaron.skomra@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/wacom_sys.c

@@ -88,7 +88,7 @@ static void wacom_wac_queue_flush(struct hid_device *hdev,
 }
 
 static int wacom_wac_pen_serial_enforce(struct hid_device *hdev,
-		struct hid_report *report, u8 *raw_data, int size)
+		struct hid_report *report, u8 *raw_data, int report_size)
 {
 	struct wacom *wacom = hid_get_drvdata(hdev);
 	struct wacom_wac *wacom_wac = &wacom->wacom_wac;
@@ -149,7 +149,8 @@ static int wacom_wac_pen_serial_enforce(struct hid_device *hdev,
 	if (flush)
 		wacom_wac_queue_flush(hdev, &wacom_wac->pen_fifo);
 	else if (insert)
-		wacom_wac_queue_insert(hdev, &wacom_wac->pen_fifo, raw_data, size);
+		wacom_wac_queue_insert(hdev, &wacom_wac->pen_fifo,
+				       raw_data, report_size);
 
 	return insert && !flush;
 }
@@ -2176,7 +2177,7 @@ static void wacom_update_name(struct wacom *wacom, const char *suffix)
 {
 	struct wacom_wac *wacom_wac = &wacom->wacom_wac;
 	struct wacom_features *features = &wacom_wac->features;
-	char name[WACOM_NAME_MAX];
+	char name[WACOM_NAME_MAX - 20]; /* Leave some room for suffixes */
 
 	/* Generic devices name unspecified */
 	if ((features->type == HID_GENERIC) && !strcmp("Wacom HID", features->name)) {

drivers/hid/wacom_wac.c

@@ -251,7 +251,7 @@ static int wacom_dtu_irq(struct wacom_wac *wacom)
 
 static int wacom_dtus_irq(struct wacom_wac *wacom)
 {
-	char *data = wacom->data;
+	unsigned char *data = wacom->data;
 	struct input_dev *input = wacom->pen_input;
 	unsigned short prox, pressure = 0;
 
@@ -572,7 +572,7 @@ static int wacom_intuos_pad(struct wacom_wac *wacom)
 		strip2 = ((data[3] & 0x1f) << 8) | data[4];
 	}
 
-	prox = (buttons & ~(~0 << nbuttons)) | (keys & ~(~0 << nkeys)) |
+	prox = (buttons & ~(~0U << nbuttons)) | (keys & ~(~0U << nkeys)) |
 	       (ring1 & 0x80) | (ring2 & 0x80) | strip1 | strip2;
 
 	wacom_report_numbered_buttons(input, nbuttons, buttons);