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drivers/usbhost: Describe a device behind a hub to the xHCI controller.

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A controller reaches a device by the path to it and, for a slow device,
through the hub that translates for it.  Neither was described, so a
device behind a hub was addressed as though it were on the root port.

The route string is that path: each hub between the device and the root
contributes a nibble holding the port the next thing down occupies, tier
nearest the root in the lowest nibble.  Walking up from the device reaches
the deepest tier first, so shifting left by a nibble each time leaves them
in the order the field wants.  The walk stops after five, which is what
the field holds and what USB allows, and a port above fifteen is clamped.

Slot context dword 2 names the transaction translator carrying a low or
full speed device behind a high speed hub.  It reports the hub by slot,
where EHCI reports it by USB address, and it names the nearest high speed
ancestor rather than the immediate parent, since a full speed hub below a
high speed one is itself carried by the translator above it.  The think
time comes from the hub descriptor by way of the hub class driver, in the
same units.

xhci_epalloc() carried a copy of sam_ehci.c's block, writing
epinfo->hubaddr and epinfo->hubport, which is how EHCI describes a split
transaction in its queue head.  This driver never read either field, and
xHCI wants the information in the slot context.  Both fields and the code
setting them are removed.

Multi-TT is not set, for the reason given in the previous commit.

No functional change: hubs cannot be enabled yet, and a device on a root
port has neither hubs above it nor a translator.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Justin Hammond <justin@dynam.ac>
This commit is contained in:
Justin Hammond 2026-08-08 14:42:38 +08:00 • committed by Xiang Xiao
parent 572b7a0b55
commit 9af6540381
2 changed files with 149 additions and 34 deletions
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162
drivers/usbhost/usbhost_xhci.c
View file

@ -176,13 +176,6 @@ struct xhci_epinfo_s
#endif
struct xhci_ring_s td; /* TD ring for this endpoint */
uint8_t slot; /* Slot where this EP resides */
/* These fields are used in the split-transaction protocol. */
uint8_t hubaddr; /* USB device address of the high-speed hub below
* which a full/low-speed device is attached.
*/
uint8_t hubport; /* The port on the above high-speed hub. */
};
/* This structure retains the state of one root hub port */
@ -394,6 +387,11 @@ static int xhci_address_set(FAR struct usbhost_xhci_s *priv,
FAR struct xhci_rhport_s *rhport, bool setaddr);
static int xhci_slot_init(FAR struct usbhost_xhci_s *priv,
FAR struct xhci_dev_s *dev);
#ifdef CONFIG_USBHOST_HUB
static uint32_t xhci_route_string(FAR struct usbhost_hubport_s *hport);
static uint32_t xhci_slot_tt(FAR struct usbhost_xhci_s *priv,
FAR struct xhci_dev_s *dev);
#endif
static int xhci_device_init(FAR struct usbhost_xhci_s *priv,
FAR struct xhci_rhport_s *rhport);
static int xhci_device_deinit(FAR struct usbhost_xhci_s *priv,
@ -1702,10 +1700,11 @@ static int xhci_slot_init(FAR struct usbhost_xhci_s *priv,
XHCI_ST_CTX0_SPEED_SET(xhci_speed_id(dev->hport->speed));
#ifdef CONFIG_USBHOST_HUB
regval |= XHCI_ST_CTX0_RTSTR_SET(xhci_route_string(dev->hport));
/* TODO:
* 1. Activate the transaction translator if required
* 2. Configure hub bit in slot context if hub
* 3. configure route string
*/
# warning missing logic
@ -1722,6 +1721,10 @@ static int xhci_slot_init(FAR struct usbhost_xhci_s *priv,
regval |= XHCI_ST_CTX1_PORTS_SET(0);
xhci_in_slot(priv, dev->input)->ctx[1] = htole32(regval);
#ifdef CONFIG_USBHOST_HUB
xhci_in_slot(priv, dev->input)->ctx[2] = htole32(xhci_slot_tt(priv, dev));
#endif
/* Step 4. the Transfer Ring for the Default Control Endpoint is already
* allocated.
*/
@ -3039,6 +3042,58 @@ xhci_dev_from_ep(FAR struct usbhost_xhci_s *priv,
*
****************************************************************************/
#ifdef CONFIG_USBHOST_HUB
/****************************************************************************
* Name: xhci_route_string
*
* Description:
* The route string for a device, which is how the controller finds it.
*
* Each hub between the root and the device contributes one nibble holding
* the number of the port the next thing down is plugged into, with the
* tier nearest the root in the lowest nibble. A device on a root hub port
* routes to zero, which is what the field means for "no hubs in between".
*
* Reference:
* - 8.9: Route String Field
*
****************************************************************************/
static uint32_t xhci_route_string(FAR struct usbhost_hubport_s *hport)
{
uint32_t route = 0;
int tier = 0;
/* Walking up reaches the deepest tier first, and shifting what is already
* there left by a nibble each time leaves the tier nearest the root in the
* lowest one. USB allows five tiers of hubs and the field holds exactly
* that many, so a chain longer than the bus permits stops here rather than
* writing over the speed field above it.
*/
while (hport->parent != NULL && tier < 5)
{
uint8_t portno = hport->port + 1;
/* The nibble cannot express a port above fifteen. A hub that large
* is legal, so clamp rather than let the number wrap into the tier
* below it.
*/
if (portno > 15)
{
portno = 15;
}
route = (route << 4) | portno;
hport = hport->parent;
tier++;
}
return route;
}
#endif
static FAR struct xhci_dev_s *
xhci_dev_from_hport(FAR struct usbhost_xhci_s *priv,
FAR struct usbhost_hubport_s *hport)
@ -3057,6 +3112,71 @@ xhci_dev_from_hport(FAR struct usbhost_xhci_s *priv,
return NULL;
}
#ifdef CONFIG_USBHOST_HUB
/****************************************************************************
* Name: xhci_slot_tt
*
* Description:
* Slot context dword 2, naming the transaction translator that carries a
* low or full speed device behind a high speed hub. Zero when no
* translator is involved, which is what the field means.
*
* Reference:
* - 6.2.2: Slot Context
*
****************************************************************************/
static uint32_t xhci_slot_tt(FAR struct usbhost_xhci_s *priv,
FAR struct xhci_dev_s *dev)
{
FAR struct usbhost_hubport_s *hport = dev->hport;
FAR struct xhci_dev_s *tthub;
/* Only a low or full speed device is translated for. */
if (hport->speed == USB_SPEED_HIGH)
{
return 0;
}
/* The translator lives in the nearest high speed ancestor, which need not
* be the hub the device is plugged into: a full speed hub below a high
* speed one is itself carried by the translator above it.
*/
while (hport->parent != NULL && hport->parent->speed != USB_SPEED_HIGH)
{
hport = hport->parent;
}
if (hport->parent == NULL)
{
/* Nothing high speed above, so the device is on a root hub port or
* the whole chain runs at its speed. Either way there is no
* translator to name.
*/
return 0;
}
tthub = xhci_dev_from_hport(priv, hport->parent);
if (tthub == NULL)
{
uerr("no device for the hub carrying port %d\n", hport->port);
return 0;
}
/* Think time is the hub's, reported by the hub class driver from the hub
* descriptor. Both fields count in the same units, so the value carries
* across unchanged.
*/
return XHCI_ST_CTX2_TTHSID_SET(tthub->slot) |
XHCI_ST_CTX2_TTPORT_SET(hport->port + 1) |
XHCI_ST_CTX2_TTT_SET(hport->parent->ttt);
}
#endif
/****************************************************************************
* Name: xhci_speed_id
*
@ -4158,32 +4278,6 @@ static int xhci_epalloc(FAR struct usbhost_driver_s *drvr,
epinfo->slot = dev->slot;
#ifdef CONFIG_USBHOST_HUB
if (hport->speed != USB_SPEED_HIGH)
{
/* A high speed hub exists between this device and the root hub
* otherwise we would not get here.
*/
FAR struct usbhost_hubport_s *parent = hport->parent;
for (; parent->speed != USB_SPEED_HIGH; parent = hport->parent)
{
hport = parent;
}
if (parent->speed == USB_SPEED_HIGH)
{
epinfo->hubport = HPORT(hport);
epinfo->hubaddr = hport->parent->funcaddr;
}
else
{
return -EINVAL;
}
}
#endif
/* Get EP type */
switch (epinfo->xfrtype)

21
drivers/usbhost/usbhost_xhci.h
View file

@ -504,6 +504,8 @@
#define XHCI_ST_CTX0_RTSTR_SHIFT (0) /* Bits 0:19: Route String */
#define XHCI_ST_CTX0_RTSTR_MASK (0xfffff << XHCI_ST_CTX0_RTSTR_SHIFT)
#define XHCI_ST_CTX0_RTSTR_SET(x) (((x) << XHCI_ST_CTX0_RTSTR_SHIFT) & \
XHCI_ST_CTX0_RTSTR_MASK)
#define XHCI_ST_CTX0_SPEED_SHIFT (20) /* Bits 20:23: Speed */
#define XHCI_ST_CTX0_SPEED_MASK (0xf << XHCI_ST_CTX0_SPEED_SHIFT)
#define XHCI_ST_CTX0_SPEED_SET(x) (((x) << XHCI_ST_CTX0_SPEED_SHIFT) & \
@ -535,6 +537,25 @@
#define XHCI_ST_CTX1_PORTS_MASK (0xff << XHCI_ST_CTX1_PORTS_SHIFT)
#define XHCI_ST_CTX1_PORTS_SET(x) (((x) << XHCI_ST_CTX1_PORTS_SHIFT) & XHCI_ST_CTX1_PORTS_MASK)
/* Slot Context dword 2 describes the transaction translator that carries a
* low or full speed device sitting behind a high speed hub. It names the
* nearest high speed ancestor, which is the hub whose TT does the work, and
* not the hub the device is plugged into if those differ.
*/
#define XHCI_ST_CTX2_TTHSID_SHIFT (0) /* Bit 0-7: TT Hub Slot ID */
#define XHCI_ST_CTX2_TTHSID_MASK (0xff << XHCI_ST_CTX2_TTHSID_SHIFT)
#define XHCI_ST_CTX2_TTHSID_SET(x) (((x) << XHCI_ST_CTX2_TTHSID_SHIFT) & \
XHCI_ST_CTX2_TTHSID_MASK)
#define XHCI_ST_CTX2_TTPORT_SHIFT (8) /* Bit 8-15: TT Port Number */
#define XHCI_ST_CTX2_TTPORT_MASK (0xff << XHCI_ST_CTX2_TTPORT_SHIFT)
#define XHCI_ST_CTX2_TTPORT_SET(x) (((x) << XHCI_ST_CTX2_TTPORT_SHIFT) & \
XHCI_ST_CTX2_TTPORT_MASK)
#define XHCI_ST_CTX2_TTT_SHIFT (16) /* Bit 16-17: TT Think Time */
#define XHCI_ST_CTX2_TTT_MASK (0x3 << XHCI_ST_CTX2_TTT_SHIFT)
#define XHCI_ST_CTX2_TTT_SET(x) (((x) << XHCI_ST_CTX2_TTT_SHIFT) & \
XHCI_ST_CTX2_TTT_MASK)
#define XHCI_ST_CTX3_ADDR_SHIFT (0) /* Bit 0-7: USB Device Address */
#define XHCI_ST_CTX3_ADDR_MASK (0xff << XHCI_ST_CTX3_ADDR_SHIFT)
#define XHCI_ST_CTX3_ADDR_SET(x) (((x) << XHCI_ST_CTX3_ADDR_SHIFT) & XHCI_ST_CTX3_ADDR_MASK)