usb: musb: host: Handle highmem in PIO mode

In case of USB bulk transfer, when himem page
is received, the usb_sg_init function sets the
urb transfer buffer to NULL. When such URB
transfer is handled, kernel crashes in PIO mode.
Handle this by mapping the highmem buffer in PIO mode.

Signed-off-by: Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>
Signed-off-by: Praveena NADAHALLY <praveen.nadahally@stericsson.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/musb/musb_host.c

@@ -823,9 +823,28 @@ static void musb_ep_program(struct musb *musb, u8 epnum,
 		if (load_count) {
 			/* PIO to load FIFO */
 			qh->segsize = load_count;
-			musb_write_fifo(hw_ep, load_count, buf);
+			if (!buf) {
+				sg_miter_start(&qh->sg_miter, urb->sg, 1,
+						SG_MITER_ATOMIC
+						| SG_MITER_FROM_SG);
+				if (!sg_miter_next(&qh->sg_miter)) {
+					dev_err(musb->controller,
+							"error: sg"
+							"list empty\n");
+					sg_miter_stop(&qh->sg_miter);
+					goto finish;
+				}
+				buf = qh->sg_miter.addr + urb->sg->offset +
+					urb->actual_length;
+				load_count = min_t(u32, load_count,
+						qh->sg_miter.length);
+				musb_write_fifo(hw_ep, load_count, buf);
+				qh->sg_miter.consumed = load_count;
+				sg_miter_stop(&qh->sg_miter);
+			} else
+				musb_write_fifo(hw_ep, load_count, buf);
 		}
-
+finish:
 		/* re-enable interrupt */
 		musb_writew(mbase, MUSB_INTRTXE, int_txe);
 
@@ -1193,6 +1212,7 @@ void musb_host_tx(struct musb *musb, u8 epnum)
 	void __iomem		*mbase = musb->mregs;
 	struct dma_channel	*dma;
 	bool			transfer_pending = false;
+	static bool use_sg;
 
 	musb_ep_select(mbase, epnum);
 	tx_csr = musb_readw(epio, MUSB_TXCSR);
@@ -1247,6 +1267,7 @@ void musb_host_tx(struct musb *musb, u8 epnum)
 			return;
 	}
 
+done:
 	if (status) {
 		if (dma_channel_status(dma) == MUSB_DMA_STATUS_BUSY) {
 			dma->status = MUSB_DMA_STATUS_CORE_ABORT;
@@ -1416,9 +1437,38 @@ void musb_host_tx(struct musb *musb, u8 epnum)
 		length = qh->maxpacket;
 	/* Unmap the buffer so that CPU can use it */
 	usb_hcd_unmap_urb_for_dma(musb_to_hcd(musb), urb);
-	musb_write_fifo(hw_ep, length, urb->transfer_buffer + offset);
+
+	/*
+	 * We need to map sg if the transfer_buffer is
+	 * NULL.
+	 */
+	if (!urb->transfer_buffer)
+		use_sg = true;
+
+	if (use_sg) {
+		/* sg_miter_start is already done in musb_ep_program */
+		if (!sg_miter_next(&qh->sg_miter)) {
+			dev_err(musb->controller, "error: sg list empty\n");
+			sg_miter_stop(&qh->sg_miter);
+			status = -EINVAL;
+			goto done;
+		}
+		urb->transfer_buffer = qh->sg_miter.addr;
+		length = min_t(u32, length, qh->sg_miter.length);
+		musb_write_fifo(hw_ep, length, urb->transfer_buffer);
+		qh->sg_miter.consumed = length;
+		sg_miter_stop(&qh->sg_miter);
+	} else {
+		musb_write_fifo(hw_ep, length, urb->transfer_buffer + offset);
+	}
+
 	qh->segsize = length;
 
+	if (use_sg) {
+		if (offset + length >= urb->transfer_buffer_length)
+			use_sg = false;
+	}
+
 	musb_ep_select(mbase, epnum);
 	musb_writew(epio, MUSB_TXCSR,
 			MUSB_TXCSR_H_WZC_BITS | MUSB_TXCSR_TXPKTRDY);
@@ -1482,6 +1532,8 @@ void musb_host_rx(struct musb *musb, u8 epnum)
 	bool			done = false;
 	u32			status;
 	struct dma_channel	*dma;
+	static bool use_sg;
+	unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG;
 
 	musb_ep_select(mbase, epnum);
 
@@ -1796,10 +1848,43 @@ void musb_host_rx(struct musb *musb, u8 epnum)
 #endif	/* Mentor DMA */
 
 		if (!dma) {
+			unsigned int received_len;
+
 			/* Unmap the buffer so that CPU can use it */
 			usb_hcd_unmap_urb_for_dma(musb_to_hcd(musb), urb);
-			done = musb_host_packet_rx(musb, urb,
-					epnum, iso_err);
+
+			/*
+			 * We need to map sg if the transfer_buffer is
+			 * NULL.
+			 */
+			if (!urb->transfer_buffer) {
+				use_sg = true;
+				sg_miter_start(&qh->sg_miter, urb->sg, 1,
+						sg_flags);
+			}
+
+			if (use_sg) {
+				if (!sg_miter_next(&qh->sg_miter)) {
+					dev_err(musb->controller, "error: sg list empty\n");
+					sg_miter_stop(&qh->sg_miter);
+					status = -EINVAL;
+					done = true;
+					goto finish;
+				}
+				urb->transfer_buffer = qh->sg_miter.addr;
+				received_len = urb->actual_length;
+				qh->offset = 0x0;
+				done = musb_host_packet_rx(musb, urb, epnum,
+						iso_err);
+				/* Calculate the number of bytes received */
+				received_len = urb->actual_length -
+					received_len;
+				qh->sg_miter.consumed = received_len;
+				sg_miter_stop(&qh->sg_miter);
+			} else {
+				done = musb_host_packet_rx(musb, urb,
+						epnum, iso_err);
+			}
 			dev_dbg(musb->controller, "read %spacket\n", done ? "last " : "");
 		}
 	}
@@ -1808,6 +1893,9 @@ finish:
 	urb->actual_length += xfer_len;
 	qh->offset += xfer_len;
 	if (done) {
+		if (use_sg)
+			use_sg = false;
+
 		if (urb->status == -EINPROGRESS)
 			urb->status = status;
 		musb_advance_schedule(musb, urb, hw_ep, USB_DIR_IN);

drivers/usb/musb/musb_host.h

@@ -35,6 +35,8 @@
 #ifndef _MUSB_HOST_H
 #define _MUSB_HOST_H
 
+#include <linux/scatterlist.h>
+
 static inline struct usb_hcd *musb_to_hcd(struct musb *musb)
 {
 	return container_of((void *) musb, struct usb_hcd, hcd_priv);
@@ -71,6 +73,7 @@ struct musb_qh {
 	u16			maxpacket;
 	u16			frame;		/* for periodic schedule */
 	unsigned		iso_idx;	/* in urb->iso_frame_desc[] */
+	struct sg_mapping_iter sg_miter;	/* for highmem in PIO mode */
 };
 
 /* map from control or bulk queue head to the first qh on that ring */