[media] rc: meson-ir: switch config to NEC decoding on shutdown

On the Amlogic SoCs, the bootloader firmware can handle the IR hardware
in order to Wake up or Power back the system when in suspend on
shutdown mode.

This patch switches the hardware configuration in a state usable by the
firmware to permit powering the system back.

Some vendor bootloader firmware were modified to switch to this
configuration but it may not be the case for all available products.

This patch was originally posted at [1].

[1] https://github.com/LibreELEC/linux-amlogic/pull/27

Signed-off-by: Alex Deryskyba <alex@codesnake.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/rc/meson-ir.c

@@ -201,6 +201,32 @@ static int meson_ir_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static void meson_ir_shutdown(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *node = dev->of_node;
+	struct meson_ir *ir = platform_get_drvdata(pdev);
+	unsigned long flags;
+
+	spin_lock_irqsave(&ir->lock, flags);
+
+	/*
+	 * Set operation mode to NEC/hardware decoding to give
+	 * bootloader a chance to power the system back on
+	 */
+	if (of_device_is_compatible(node, "amlogic,meson6-ir"))
+		meson_ir_set_mask(ir, IR_DEC_REG1, REG1_MODE_MASK,
+				  DECODE_MODE_NEC << REG1_MODE_SHIFT);
+	else
+		meson_ir_set_mask(ir, IR_DEC_REG2, REG2_MODE_MASK,
+				  DECODE_MODE_NEC << REG2_MODE_SHIFT);
+
+	/* Set rate to default value */
+	meson_ir_set_mask(ir, IR_DEC_REG0, REG0_RATE_MASK, 0x13);
+
+	spin_unlock_irqrestore(&ir->lock, flags);
+}
+
 static const struct of_device_id meson_ir_match[] = {
 	{ .compatible = "amlogic,meson6-ir" },
 	{ .compatible = "amlogic,meson8b-ir" },
@@ -212,6 +238,7 @@ MODULE_DEVICE_TABLE(of, meson_ir_match);
 static struct platform_driver meson_ir_driver = {
 	.probe		= meson_ir_probe,
 	.remove		= meson_ir_remove,
+	.shutdown	= meson_ir_shutdown,
 	.driver = {
 		.name		= DRIVER_NAME,
 		.of_match_table	= meson_ir_match,