libpayload: usb mass storage card hot plug

Mass storage devices such as card readers show up as
as USB devices. However the media not be inserted. In those
situations the previous code would just fake a disk and
call usbcreate_disk. This is inappropriate because it forms
a 1:1 mapping of USB device to disk leading to the inability
to remove the disk and/or handle "hot plug" card insertion
and removals.

To alleviate this issue introduce the notion of ready to the
usbmsc structure. It tracks detached, not ready, and ready
states. The polling routine is then used to track not ready
to ready transitions thereby creating and removing disks
appropriately. This handles the case of inserting and removing
a card that shows up as a new disk.

Booted recovery mode. Able to observe inerstion and removal
of sdcard. Also able to insert valid USB flash drive to boot
as well.

Change-Id: I3eefbe537ec1b9c975744b8984b06c17ae236f40
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/57948
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/4226
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

2 files changed, 157 insertions, 53 deletions

diff --git a/payloads/libpayload/drivers/usb/usbmsc.c b/payloads/libpayload/drivers/usb/usbmsc.c
index ffb1c93..f1de483 100644
--- a/payloads/libpayload/drivers/usb/usbmsc.c
+++ b/payloads/libpayload/drivers/usb/usbmsc.c
@@ -67,21 +67,60 @@ static const char *msc_protocol_strings[0x51] = {
 	"Bulk-Only Transport"
 };
 
+static inline void
+usb_msc_mark_ready (usbdev_t *dev)
+{
+	MSC_INST (dev)->ready = USB_MSC_READY;
+}
+
+static inline void
+usb_msc_mark_not_ready (usbdev_t *dev)
+{
+	MSC_INST (dev)->ready = USB_MSC_NOT_READY;
+}
+
+static inline void
+usb_msc_mark_detached (usbdev_t *dev)
+{
+	MSC_INST (dev)->ready = USB_MSC_DETACHED;
+}
+
+static inline int
+usb_msc_is_detached (usbdev_t *dev)
+{
+	return MSC_INST (dev)->ready == USB_MSC_DETACHED;
+}
+
+static inline int
+usb_msc_is_ready (usbdev_t *dev)
+{
+	return MSC_INST (dev)->ready == USB_MSC_READY;
+}
 
 static void
-usb_msc_destroy (usbdev_t *dev)
+usb_msc_create_disk (usbdev_t *dev)
 {
-	if (dev->data) {
-		if (MSC_INST (dev)->usbdisk_created && usbdisk_remove)
-			usbdisk_remove (dev);
-		free (dev->data);
+	if (usbdisk_create) {
+		usbdisk_create (dev);
+		MSC_INST (dev)->usbdisk_created = 1;
 	}
-	dev->data = 0;
 }
 
 static void
-usb_msc_poll (usbdev_t *dev)
+usb_msc_remove_disk (usbdev_t *dev)
 {
+	if (MSC_INST (dev)->usbdisk_created && usbdisk_remove)
+		usbdisk_remove (dev);
+}
+
+static void
+usb_msc_destroy (usbdev_t *dev)
+{
+	if (dev->data) {
+		usb_msc_remove_disk (dev);
+		free (dev->data);
+	}
+	dev->data = 0;
 }
 
 const int DEV_RESET = 0xff;
@@ -125,6 +164,8 @@ static int
 request_sense (usbdev_t *dev);
 static int
 request_sense_no_media (usbdev_t *dev);
+static void
+usb_msc_poll (usbdev_t *dev);
 
 static int
 reset_transport (usbdev_t *dev)
@@ -357,7 +398,7 @@ request_sense (usbdev_t *dev)
 				sizeof (cb), buf, 19, 1);
 }
 
-static int request_sense_no_media(usbdev_t *dev)
+static int request_sense_no_media (usbdev_t *dev)
 {
 	u8 buf[19];
 	int ret;
@@ -379,10 +420,11 @@ static int request_sense_no_media(usbdev_t *dev)
 	if (buf[12] != 0x3a)
 		return MSC_COMMAND_FAIL;
 
-	/* No media is present. Return MSC_COMMAND_DETACHED so as not to use
-	 * this device any longer. */
-	usb_debug("Empty media found.\n");
-	return MSC_COMMAND_DETACHED;
+	/* No media is present. Return MSC_COMMAND_OK while marking the disk
+	 * not ready. */
+	usb_debug ("Empty media found.\n");
+	usb_msc_mark_not_ready (dev);
+	return MSC_COMMAND_OK;
 }
 
 static int
@@ -446,10 +488,74 @@ read_capacity (usbdev_t *dev)
 	return MSC_COMMAND_OK;
 }
 
+static void
+usb_msc_test_unit_ready (usbdev_t *dev)
+{
+	int i;
+	/* SCSI/ATA specs say we have to wait up to 30s. Ugh */
+	const int timeout = 30 * 10;
+
+	usb_debug ("  Waiting for device to become ready...");
+
+	/* Initially mark the device ready. */
+	usb_msc_mark_ready (dev);
+
+	for (i = 0; i < timeout; i++) {
+		switch (test_unit_ready (dev)) {
+		case MSC_COMMAND_OK:
+			break;
+		case MSC_COMMAND_FAIL:
+			mdelay (100);
+			if (!(timeout % 10))
+				usb_debug (".");
+			continue;
+		default:
+			usb_debug ("detached. Device not ready.\n");
+			usb_msc_mark_detached (dev);
+			return;
+		}
+		break;
+	}
+	if (i >= timeout) {
+		usb_debug ("timeout. Device not ready.\n");
+		usb_msc_mark_not_ready (dev);
+	}
+
+	/* Don't bother spinning up the stroage device if the device is not
+	 * ready. This can happen when empty card readers are present.
+	 * Polling will pick it back up if readiness changes. */
+	if (!usb_msc_is_ready (dev))
+		return;
+
+	usb_debug ("ok.\n");
+
+	usb_debug ("  spin up");
+	for (i = 0; i < 30; i++) {
+		usb_debug (".");
+		switch (spin_up (dev)) {
+		case MSC_COMMAND_OK:
+			usb_debug (" OK.");
+			break;
+		case MSC_COMMAND_FAIL:
+			mdelay (100);
+			continue;
+		default:
+			/* Device is no longer ready. */
+			usb_msc_mark_detached (dev);
+			return;
+		}
+		break;
+	}
+	usb_debug ("\n");
+
+	if (read_capacity (dev) != MSC_COMMAND_OK)
+		usb_msc_mark_not_ready (dev);
+}
+
 void
 usb_msc_init (usbdev_t *dev)
 {
-	int i, timeout;
+	int i;
 
 	/* init .data before setting .destroy */
 	dev->data = NULL;
@@ -489,6 +595,7 @@ usb_msc_init (usbdev_t *dev)
 	MSC_INST (dev)->bulk_in = 0;
 	MSC_INST (dev)->bulk_out = 0;
 	MSC_INST (dev)->usbdisk_created = 0;
+	usb_msc_mark_ready (dev);
 
 	for (i = 1; i <= dev->num_endp; i++) {
 		if (dev->endpoints[i].endpoint == 0)
@@ -517,47 +624,36 @@ usb_msc_init (usbdev_t *dev)
 
 	usb_debug ("  has %d luns\n", get_max_luns (dev) + 1);
 
-	usb_debug ("  Waiting for device to become ready...");
-	timeout = 30 * 10; /* SCSI/ATA specs say we have to wait up to 30s. Ugh */
-	while (timeout--) {
-		switch (test_unit_ready (dev)) {
-		case MSC_COMMAND_OK:
-			break;
-		case MSC_COMMAND_FAIL:
-			mdelay (100);
-			if (!(timeout % 10))
-				usb_debug (".");
-			continue;
-		default: /* if it's worse return */
-			return;
-		}
-		break;
-	}
-	if (timeout < 0) {
-		usb_debug ("timeout. Device not ready. Still trying...\n");
-	} else {
-		usb_debug ("ok.\n");
-	}
+	/* Test if unit is ready. */
+	usb_msc_test_unit_ready (dev);
 
-	usb_debug ("  spin up");
-	for (i = 0; i < 30; i++) {
-		usb_debug (".");
-		switch (spin_up (dev)) {
-		case MSC_COMMAND_OK:
-			usb_debug (" OK.");
-			break;
-		case MSC_COMMAND_FAIL:
-			mdelay (100);
-			continue;
-		default: /* if it's worse return */
-			return;
-		}
-		break;
-	}
-	usb_debug ("\n");
+	/* Nothing to do if device is not ready. */
+	if (!usb_msc_is_ready (dev))
+		return;
 
-	if ((read_capacity (dev) == MSC_COMMAND_OK) && usbdisk_create) {
-		usbdisk_create (dev);
-		MSC_INST (dev)->usbdisk_created = 1;
+	/* Create the disk. */
+	usb_msc_create_disk (dev);
+}
+
+static void
+usb_msc_poll (usbdev_t *dev)
+{
+	int prev_ready;
+
+	/* Nothing to do if device is detached. */
+	if (usb_msc_is_detached (dev))
+		return;
+
+	/* Handle ready transitions by keeping track of previous state . */
+	prev_ready = usb_msc_is_ready (dev);
+
+	usb_msc_test_unit_ready (dev);
+
+	if (!prev_ready && usb_msc_is_ready (dev)) {
+		usb_debug ("usb msc: not ready -> ready\n");
+		usb_msc_create_disk (dev);
+	} else if (prev_ready && !usb_msc_is_ready (dev)) {
+		usb_debug ("usb msc: ready -> not ready\n");
+		usb_msc_remove_disk (dev);
 	}
 }
diff --git a/payloads/libpayload/include/usb/usbmsc.h b/payloads/libpayload/include/usb/usbmsc.h
index 5c3dadc..8930156 100644
--- a/payloads/libpayload/include/usb/usbmsc.h
+++ b/payloads/libpayload/include/usb/usbmsc.h
@@ -36,9 +36,17 @@ typedef struct {
 	endpoint_t *bulk_in;
 	endpoint_t *bulk_out;
 	int usbdisk_created;
+	int ready;
 	void *data; /* For use by consumers of libpayload. */
 } usbmsc_inst_t;
 
+/* Possible values for ready field. */
+enum {
+	USB_MSC_DETACHED = -1, /* Disk detached or out to lunch. */
+	USB_MSC_NOT_READY = 0, /* Disk not ready yet -- empty card reader */
+	USB_MSC_READY = 1,     /* Disk ready to communicate. */
+};
+
 #define MSC_INST(dev) ((usbmsc_inst_t*)(dev)->data)
 
 typedef enum { cbw_direction_data_in = 0x80, cbw_direction_data_out = 0