[media] em28xx: add support for NEC proto variants on em2874 and upper

By disabling the NEC parity check, it is possible to handle all 3 NEC
protocol variants (32, 24 or 16 bits).
Change the driver in order to handle all of them.
Unfortunately, em2860/em2863 provide only 16 bits for the IR scancode,
even when NEC parity is disabled. So, this change should affect only
em2874 and newer devices, with provides up to 32 bits for the scancode.
Tested with one NEC-16, one NEC-24 and one RC5 IR.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/usb/em28xx/em28xx-input.c

@@ -57,8 +57,8 @@ MODULE_PARM_DESC(ir_debug, "enable debug messages [IR]");
 struct em28xx_ir_poll_result {
 	unsigned int toggle_bit:1;
 	unsigned int read_count:7;
-	u8 rc_address;
-	u8 rc_data[4]; /* 1 byte on em2860/2880, 4 on em2874 */
+
+	u32 scancode;
 };
 
 struct em28xx_IR {
@@ -72,6 +72,7 @@ struct em28xx_IR {
 	struct delayed_work work;
 	unsigned int full_code:1;
 	unsigned int last_readcount;
+	u64 rc_type;
 
 	int  (*get_key)(struct em28xx_IR *, struct em28xx_ir_poll_result *);
 };
@@ -236,11 +237,8 @@ static int default_polling_getkey(struct em28xx_IR *ir,
 	/* Infrared read count (Reg 0x45[6:0] */
 	poll_result->read_count = (msg[0] & 0x7f);
 
-	/* Remote Control Address (Reg 0x46) */
-	poll_result->rc_address = msg[1];
-
-	/* Remote Control Data (Reg 0x47) */
-	poll_result->rc_data[0] = msg[2];
+	/* Remote Control Address/Data (Regs 0x46/0x47) */
+	poll_result->scancode = msg[1] << 8 | msg[2];
 
 	return 0;
 }
@@ -266,13 +264,32 @@ static int em2874_polling_getkey(struct em28xx_IR *ir,
 	/* Infrared read count (Reg 0x51[6:0] */
 	poll_result->read_count = (msg[0] & 0x7f);
 
-	/* Remote Control Address (Reg 0x52) */
-	poll_result->rc_address = msg[1];
-
-	/* Remote Control Data (Reg 0x53-55) */
-	poll_result->rc_data[0] = msg[2];
-	poll_result->rc_data[1] = msg[3];
-	poll_result->rc_data[2] = msg[4];
+	/*
+	 * Remote Control Address (Reg 0x52)
+	 * Remote Control Data (Reg 0x53-0x55)
+	 */
+	switch (ir->rc_type) {
+	case RC_BIT_RC5:
+		poll_result->scancode = msg[1] << 8 | msg[2];
+		break;
+	case RC_BIT_NEC:
+		if ((msg[3] ^ msg[4]) != 0xff)		/* 32 bits NEC */
+			poll_result->scancode = (msg[1] << 24) |
+						(msg[2] << 16) |
+						(msg[3] << 8)  |
+						 msg[4];
+		else if ((msg[1] ^ msg[2]) != 0xff)	/* 24 bits NEC */
+			poll_result->scancode = (msg[1] << 16) |
+						(msg[2] << 8)  |
+						 msg[3];
+		else					/* Normal NEC */
+			poll_result->scancode = msg[1] << 8 | msg[3];
+		break;
+	default:
+		poll_result->scancode = (msg[1] << 24) | (msg[2] << 16) |
+					(msg[3] << 8)  | msg[4];
+		break;
+	}
 
 	return 0;
 }
@@ -294,17 +311,16 @@ static void em28xx_ir_handle_key(struct em28xx_IR *ir)
 	}
 
 	if (unlikely(poll_result.read_count != ir->last_readcount)) {
-		dprintk("%s: toggle: %d, count: %d, key 0x%02x%02x\n", __func__,
+		dprintk("%s: toggle: %d, count: %d, key 0x%04x\n", __func__,
 			poll_result.toggle_bit, poll_result.read_count,
-			poll_result.rc_address, poll_result.rc_data[0]);
+			poll_result.scancode);
 		if (ir->full_code)
 			rc_keydown(ir->rc,
-				   poll_result.rc_address << 8 |
-				   poll_result.rc_data[0],
+				   poll_result.scancode,
 				   poll_result.toggle_bit);
 		else
 			rc_keydown(ir->rc,
-				   poll_result.rc_data[0],
+				   poll_result.scancode & 0xff,
 				   poll_result.toggle_bit);
 
 		if (ir->dev->chip_id == CHIP_ID_EM2874 ||
@@ -360,12 +376,14 @@ static int em28xx_ir_change_protocol(struct rc_dev *rc_dev, u64 *rc_type)
 		*rc_type = RC_BIT_RC5;
 	} else if (*rc_type & RC_BIT_NEC) {
 		dev->board.xclk &= ~EM28XX_XCLK_IR_RC5_MODE;
-		ir_config = EM2874_IR_NEC;
+		ir_config = EM2874_IR_NEC | EM2874_IR_NEC_NO_PARITY;
 		ir->full_code = 1;
 		*rc_type = RC_BIT_NEC;
 	} else if (*rc_type != RC_BIT_UNKNOWN)
 		rc = -EINVAL;
 
+	ir->rc_type = *rc_type;
+
 	em28xx_write_reg_bits(dev, EM28XX_R0F_XCLK, dev->board.xclk,
 			      EM28XX_XCLK_IR_RC5_MODE);
 

drivers/media/usb/em28xx/em28xx-reg.h

@@ -177,6 +177,7 @@
 
 /* em2874 IR config register (0x50) */
 #define EM2874_IR_NEC           0x00
+#define EM2874_IR_NEC_NO_PARITY 0x01
 #define EM2874_IR_RC5           0x04
 #define EM2874_IR_RC6_MODE_0    0x08
 #define EM2874_IR_RC6_MODE_6A   0x0b