HID: uclogic: Allow to generate frame templates

Add a new template placeholder to allow configuring the number of
buttons in the drawing tablet frame and update the KUnit tests to
cover the new case.
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-uclogic-rdesc-test.c

@@ -31,6 +31,10 @@ static const s32 params_pen_some[] = {
 	[UCLOGIC_RDESC_PEN_PH_ID_X_PM] = 0xBB,
 };
 
+static const s32 params_frame_all[UCLOGIC_RDESC_PH_ID_NUM] = {
+	[UCLOGIC_RDESC_FRAME_PH_ID_UM] = 0xFF,
+};
+
 static const __u8 template_empty[] = { };
 static const __u8 template_small[] = { 0x00 };
 static const __u8 template_no_ph[] = { 0xAA, 0xFE, 0xAA, 0xED, 0x1D };
@@ -39,6 +43,10 @@ static const __u8 template_pen_ph_end[] = {
 	0xAA, 0xBB, UCLOGIC_RDESC_PEN_PH_HEAD
 };
 
+static const __u8 template_btn_ph_end[] = {
+	0xAA, 0xBB, UCLOGIC_RDESC_FRAME_PH_BTN_HEAD
+};
+
 static const __u8 template_pen_all_params[] = {
 	UCLOGIC_RDESC_PEN_PH(X_LM),
 	0x47, UCLOGIC_RDESC_PEN_PH(X_PM),
@@ -55,6 +63,18 @@ static const __u8 expected_pen_all_params[] = {
 	0x00, 0xEE, 0x00, 0x00, 0x00,
 };
 
+static const __u8 template_frame_all_params[] = {
+	0x01, 0x02,
+	UCLOGIC_RDESC_FRAME_PH_BTN,
+	0x99,
+};
+
+static const __u8 expected_frame_all_params[] = {
+	0x01, 0x02,
+	0x2A, 0xFF, 0x00,
+	0x99,
+};
+
 static const __u8 template_pen_some_params[] = {
 	0x01, 0x02,
 	UCLOGIC_RDESC_PEN_PH(X_LM),
@@ -108,6 +128,14 @@ static struct uclogic_template_case uclogic_template_cases[] = {
 		.param_num = ARRAY_SIZE(params_pen_all),
 		.expected = template_pen_ph_end,
 	},
+	{
+		.name = "Frame button placeholder at the end, without ID",
+		.template = template_btn_ph_end,
+		.template_size = sizeof(template_btn_ph_end),
+		.param_list = params_frame_all,
+		.param_num = ARRAY_SIZE(params_frame_all),
+		.expected = template_btn_ph_end,
+	},
 	{
 		.name = "All params present in the pen template",
 		.template = template_pen_all_params,
@@ -116,6 +144,14 @@ static struct uclogic_template_case uclogic_template_cases[] = {
 		.param_num = ARRAY_SIZE(params_pen_all),
 		.expected = expected_pen_all_params,
 	},
+	{
+		.name = "All params present in the frame template",
+		.template = template_frame_all_params,
+		.template_size = sizeof(template_frame_all_params),
+		.param_list = params_frame_all,
+		.param_num = ARRAY_SIZE(params_frame_all),
+		.expected = expected_frame_all_params,
+	},
 	{
 		.name = "Some params present in the pen template (complete param list)",
 		.template = template_pen_some_params,

drivers/hid/hid-uclogic-rdesc.c

@@ -979,7 +979,7 @@ const size_t uclogic_rdesc_xppen_deco01_frame_size =
  * uclogic_rdesc_template_apply() - apply report descriptor parameters to a
  * report descriptor template, creating a report descriptor. Copies the
  * template over to the new report descriptor and replaces every occurrence of
- * UCLOGIC_RDESC_PEN_PH_HEAD, followed by an index byte, with the value from the
+ * the template placeholders, followed by an index byte, with the value from the
  * parameter list at that index.
  *
  * @template_ptr:	Pointer to the template buffer.
@@ -996,6 +996,7 @@ __u8 *uclogic_rdesc_template_apply(const __u8 *template_ptr,
 				   const s32 *param_list,
 				   size_t param_num)
 {
+	static const __u8 btn_head[] = {UCLOGIC_RDESC_FRAME_PH_BTN_HEAD};
 	static const __u8 pen_head[] = {UCLOGIC_RDESC_PEN_PH_HEAD};
 	__u8 *rdesc_ptr;
 	__u8 *p;
@@ -1005,12 +1006,19 @@ __u8 *uclogic_rdesc_template_apply(const __u8 *template_ptr,
 	if (rdesc_ptr == NULL)
 		return NULL;
 
-	for (p = rdesc_ptr; p + sizeof(pen_head) < rdesc_ptr + template_size;) {
-		if (memcmp(p, pen_head, sizeof(pen_head)) == 0 &&
+	for (p = rdesc_ptr; p + sizeof(btn_head) < rdesc_ptr + template_size;) {
+		if (p + sizeof(pen_head) < rdesc_ptr + template_size &&
+		    memcmp(p, pen_head, sizeof(pen_head)) == 0 &&
 		    p[sizeof(pen_head)] < param_num) {
 			v = param_list[p[sizeof(pen_head)]];
 			put_unaligned(cpu_to_le32(v), (s32 *)p);
 			p += sizeof(pen_head) + 1;
+		} else if (memcmp(p, btn_head, sizeof(btn_head)) == 0 &&
+			   p[sizeof(btn_head)] < param_num) {
+			v = param_list[p[sizeof(btn_head)]];
+			put_unaligned((__u8)0x2A, p); /* Usage Maximum */
+			put_unaligned_le16((__force u16)cpu_to_le16(v), p + 1);
+			p += sizeof(btn_head) + 1;
 		} else {
 			p++;
 		}

drivers/hid/hid-uclogic-rdesc.h

@@ -82,6 +82,7 @@ extern const size_t uclogic_rdesc_twha60_fixed1_size;
 
 /* Report descriptor template placeholder head */
 #define UCLOGIC_RDESC_PEN_PH_HEAD	0xFE, 0xED, 0x1D
+#define UCLOGIC_RDESC_FRAME_PH_BTN_HEAD	0xFE, 0xED
 
 /* Apply report descriptor parameters to a report descriptor template */
 extern __u8 *uclogic_rdesc_template_apply(const __u8 *template_ptr,
@@ -96,6 +97,7 @@ enum uclogic_rdesc_ph_id {
 	UCLOGIC_RDESC_PEN_PH_ID_Y_LM,
 	UCLOGIC_RDESC_PEN_PH_ID_Y_PM,
 	UCLOGIC_RDESC_PEN_PH_ID_PRESSURE_LM,
+	UCLOGIC_RDESC_FRAME_PH_ID_UM,
 	UCLOGIC_RDESC_PH_ID_NUM
 };
 
@@ -103,6 +105,10 @@ enum uclogic_rdesc_ph_id {
 #define UCLOGIC_RDESC_PEN_PH(_ID) \
 	UCLOGIC_RDESC_PEN_PH_HEAD, UCLOGIC_RDESC_PEN_PH_ID_##_ID
 
+/* Report descriptor frame buttons template placeholder */
+#define UCLOGIC_RDESC_FRAME_PH_BTN \
+	UCLOGIC_RDESC_FRAME_PH_BTN_HEAD, UCLOGIC_RDESC_FRAME_PH_ID_UM
+
 /* Report ID for v1 pen reports */
 #define UCLOGIC_RDESC_V1_PEN_ID	0x07