usb: hub: Parse and save TT details from device descriptor

A high speed hub has a special responsibility to handle full speed/
low speed devices connected on downstream ports. In this case, the
hub must isolate the high speed signaling environment from the full
speed/low speed signaling environment with the help of Transaction
Translator (TT). TT details are provided by hub descriptors and we
parse and save it to hub uclass_priv for later use.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

diff --git a/common/usb_hub.c b/common/usb_hub.c
index 18c366ab7e0b800850c2efdab1447c2ec7758d7e..bbb1155089644f24379c947ef86844dc16f5486a 100644 (file)
--- a/common/usb_hub.c
+++ b/common/usb_hub.c
@@ -700,6 +700,56 @@ static int usb_hub_configure(struct usb_device *dev)
                break;
        }
 
+       switch (dev->descriptor.bDeviceProtocol) {
+       case USB_HUB_PR_FS:
+               break;
+       case USB_HUB_PR_HS_SINGLE_TT:
+               debug("Single TT\n");
+               break;
+       case USB_HUB_PR_HS_MULTI_TT:
+               ret = usb_set_interface(dev, 0, 1);
+               if (ret == 0) {
+                       debug("TT per port\n");
+                       hub->tt.multi = true;
+               } else {
+                       debug("Using single TT (err %d)\n", ret);
+               }
+               break;
+       case USB_HUB_PR_SS:
+               /* USB 3.0 hubs don't have a TT */
+               break;
+       default:
+               debug("Unrecognized hub protocol %d\n",
+                     dev->descriptor.bDeviceProtocol);
+               break;
+       }
+
+       /* Note 8 FS bit times == (8 bits / 12000000 bps) ~= 666ns */
+       switch (hubCharacteristics & HUB_CHAR_TTTT) {
+       case HUB_TTTT_8_BITS:
+               if (dev->descriptor.bDeviceProtocol != 0) {
+                       hub->tt.think_time = 666;
+                       debug("TT requires at most %d FS bit times (%d ns)\n",
+                             8, hub->tt.think_time);
+               }
+               break;
+       case HUB_TTTT_16_BITS:
+               hub->tt.think_time = 666 * 2;
+               debug("TT requires at most %d FS bit times (%d ns)\n",
+                     16, hub->tt.think_time);
+               break;
+       case HUB_TTTT_24_BITS:
+               hub->tt.think_time = 666 * 3;
+               debug("TT requires at most %d FS bit times (%d ns)\n",
+                     24, hub->tt.think_time);
+               break;
+       case HUB_TTTT_32_BITS:
+               hub->tt.think_time = 666 * 4;
+               debug("TT requires at most %d FS bit times (%d ns)\n",
+                     32, hub->tt.think_time);
+               break;
+       }
+
        debug("power on to power good time: %dms\n",
              descriptor->bPwrOn2PwrGood * 2);
        debug("hub controller current requirement: %dmA\n",

diff --git a/include/usb.h b/include/usb.h
index f71da52b55afa25988270c87436ece4e333f6d5b..58b4549065a9dde21c721b247d248b5f426e74e6 100644 (file)
--- a/include/usb.h
+++ b/include/usb.h
@@ -537,6 +537,21 @@ struct usb_hub_status {
        unsigned short wHubChange;
 } __attribute__ ((packed));
 
+/*
+ * Hub Device descriptor
+ * USB Hub class device protocols
+ */
+#define USB_HUB_PR_FS          0 /* Full speed hub */
+#define USB_HUB_PR_HS_NO_TT    0 /* Hi-speed hub without TT */
+#define USB_HUB_PR_HS_SINGLE_TT        1 /* Hi-speed hub with single TT */
+#define USB_HUB_PR_HS_MULTI_TT 2 /* Hi-speed hub with multiple TT */
+#define USB_HUB_PR_SS          3 /* Super speed hub */
+
+/* Transaction Translator Think Times, in bits */
+#define HUB_TTTT_8_BITS                0x00
+#define HUB_TTTT_16_BITS       0x20
+#define HUB_TTTT_24_BITS       0x40
+#define HUB_TTTT_32_BITS       0x60
 
 /* Hub descriptor */
 struct usb_hub_descriptor {
@@ -571,6 +586,7 @@ struct usb_hub_device {
        ulong query_delay;              /* Device query delay in ms */
        int overcurrent_count[USB_MAXCHILDREN]; /* Over-current counter */
        int hub_depth;                  /* USB 3.0 hub depth */
+       struct usb_tt tt;               /* Transaction Translator */
 };
 
 #ifdef CONFIG_DM_USB

diff --git a/include/usb_defs.h b/include/usb_defs.h
index 273337f46a47d7fb9a7537351fa09a3299546a9c..b7f2eada07d0e7e711124aaa7f664cc130fbcbb4 100644 (file)
--- a/include/usb_defs.h
+++ b/include/usb_defs.h
@@ -293,6 +293,7 @@
 #define HUB_CHAR_LPSM               0x0003
 #define HUB_CHAR_COMPOUND           0x0004
 #define HUB_CHAR_OCPM               0x0018
+#define HUB_CHAR_TTTT               0x0060 /* TT Think Time mask */
 
 /*
  * Hub Status & Hub Change bit masks
@@ -309,6 +310,17 @@
 /* Hub class request codes */
 #define USB_REQ_SET_HUB_DEPTH  0x0c
 
+/*
+ * As of USB 2.0, full/low speed devices are segregated into trees.
+ * One type grows from USB 1.1 host controllers (OHCI, UHCI etc).
+ * The other type grows from high speed hubs when they connect to
+ * full/low speed devices using "Transaction Translators" (TTs).
+ */
+struct usb_tt {
+       bool            multi;          /* true means one TT per port */
+       unsigned        think_time;     /* think time in ns */
+};
+
 /*
  * CBI style
  */