[PATCH v3 2/7] usb: musb: dma: Add support for shared IRQ

[Paul Cercueil]

The implementation of the Inventra IP in some of the Ingenic JZ47xx SoCs
does not use a separate IRQ line for DMA transfers.

Allow these SoCs to be supported by adding a flag 'dma_share_usb_irq'
in the struct musb. If set, no extra IRQ line is required, and the musb
glue will need to call the API function musbhs_dma_controller_irq()
within its interrupt handler.

Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
Tested-by: Artur Rojek <contact@xxxxxxxxxxxxxx>
---

Notes:
    v2: Rebase on 5.4-rc4
    v3: Rebase on 5.5-rc1

 drivers/usb/musb/musb_core.h |  2 ++
 drivers/usb/musb/musb_dma.h  |  1 +
 drivers/usb/musb/musbhsdma.c | 27 ++++++++++++++++++++++-----
 3 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/musb/musb_core.h b/drivers/usb/musb/musb_core.h
index 04203b7126d5..b7c31c717800 100644
--- a/drivers/usb/musb/musb_core.h
+++ b/drivers/usb/musb/musb_core.h
@@ -392,6 +392,8 @@ struct musb {
 
 	unsigned		flush_irq_work:1;
 
+	unsigned		dma_share_usb_irq:1;
+
 	u8			address;
 	u8			test_mode_nr;
 	u16			ackpend;		/* ep0 */
diff --git a/drivers/usb/musb/musb_dma.h b/drivers/usb/musb/musb_dma.h
index 8f60271c0a9d..b3f65016a972 100644
--- a/drivers/usb/musb/musb_dma.h
+++ b/drivers/usb/musb/musb_dma.h
@@ -191,6 +191,7 @@ extern void (*musb_dma_controller_destroy)(struct dma_controller *);
 extern struct dma_controller *
 musbhs_dma_controller_create(struct musb *musb, void __iomem *base);
 extern void musbhs_dma_controller_destroy(struct dma_controller *c);
+extern irqreturn_t musbhs_dma_controller_irq(struct dma_controller *c);
 
 extern struct dma_controller *
 tusb_dma_controller_create(struct musb *musb, void __iomem *base);
diff --git a/drivers/usb/musb/musbhsdma.c b/drivers/usb/musb/musbhsdma.c
index 2d3751d885b4..898856e9974e 100644
--- a/drivers/usb/musb/musbhsdma.c
+++ b/drivers/usb/musb/musbhsdma.c
@@ -268,7 +268,7 @@ static int dma_channel_abort(struct dma_channel *channel)
 	return 0;
 }
 
-static irqreturn_t dma_controller_irq(int irq, void *private_data)
+static irqreturn_t dma_controller_irq_cb(int irq, void *private_data)
 {
 	struct musb_dma_controller *controller = private_data;
 	struct musb *musb = controller->private_data;
@@ -292,6 +292,9 @@ static irqreturn_t dma_controller_irq(int irq, void *private_data)
 	int_hsdma = musb_readb(mbase, MUSB_HSDMA_INTR);
 
 	if (!int_hsdma) {
+		if (musb->dma_share_usb_irq)
+			goto done;
+
 		musb_dbg(musb, "spurious DMA irq");
 
 		for (bchannel = 0; bchannel < MUSB_HSDMA_CHANNELS; bchannel++) {
@@ -384,6 +387,15 @@ static irqreturn_t dma_controller_irq(int irq, void *private_data)
 	return retval;
 }
 
+irqreturn_t musbhs_dma_controller_irq(struct dma_controller *c)
+{
+	struct musb_dma_controller *controller = container_of(c,
+			struct musb_dma_controller, controller);
+
+	return dma_controller_irq_cb(controller->irq, controller);
+}
+EXPORT_SYMBOL_GPL(musbhs_dma_controller_irq);
+
 void musbhs_dma_controller_destroy(struct dma_controller *c)
 {
 	struct musb_dma_controller *controller = container_of(c,
@@ -404,9 +416,14 @@ struct dma_controller *musbhs_dma_controller_create(struct musb *musb,
 	struct musb_dma_controller *controller;
 	struct device *dev = musb->controller;
 	struct platform_device *pdev = to_platform_device(dev);
-	int irq = platform_get_irq_byname(pdev, "dma");
+	int irq;
+
+	if (musb->dma_share_usb_irq)
+		irq = 0;
+	else
+		irq = platform_get_irq_byname(pdev, "dma");
 
-	if (irq <= 0) {
+	if (irq < 0) {
 		dev_err(dev, "No DMA interrupt line!\n");
 		return NULL;
 	}
@@ -424,8 +441,8 @@ struct dma_controller *musbhs_dma_controller_create(struct musb *musb,
 	controller->controller.channel_program = dma_channel_program;
 	controller->controller.channel_abort = dma_channel_abort;
 
-	if (request_irq(irq, dma_controller_irq, 0,
-			dev_name(musb->controller), controller)) {
+	if (irq > 0 && request_irq(irq, dma_controller_irq_cb, 0,
+				   dev_name(musb->controller), controller)) {
 		dev_err(dev, "request_irq %d failed!\n", irq);
 		musb_dma_controller_destroy(&controller->controller);
 
-- 
2.24.0