[RFC,03/12] xue: reset XHCI ports when initializing dbc

Commit Message

Marek Marczykowski-Górecki June 6, 2022, 3:40 a.m. UTC

Reset ports, to force host system to re-enumerate devices. Otheriwse it
will require the cable to be re-plugged, or will wait in the
"configuring" state indefinitely.

Trick and code copied from Linux:
drivers/usb/early/xhci-dbc.c:xdbc_start()->xdbc_reset_debug_port()

Signed-off-by: Marek Marczykowski-Górecki <[e-mail]>
---
 xen/include/xue.h | 69 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 69 insertions(+)

Patch

diff --git a/xen/include/xue.h b/xen/include/xue.h
index 7515244f6af3..6048dcdd5509 100644
--- a/xen/include/xue.h
+++ b/xen/include/xue.h
@@ -59,6 +59,10 @@ 
     ((1UL << XUE_PSC_CSC) | (1UL << XUE_PSC_PRC) | (1UL << XUE_PSC_PLC) |      \
      (1UL << XUE_PSC_CEC))
 
+#define     XUE_XHC_EXT_PORT_MAJOR(x)  (((x) >> 24) & 0xff)
+#define PORT_RESET  (1 << 4)
+#define PORT_CONNECT  (1 << 0)
+
 static inline int known_xhc(uint32_t dev_ven)
 {
     switch (dev_ven) {
@@ -1420,6 +1424,67 @@  static inline void xue_init_strings(struct xue *xue, uint32_t *info)
     info[8] = (4 << 24) | (30 << 16) | (8 << 8) | 6;
 }
 
+static inline void xue_do_reset_debug_port(struct xue *xue, u32 id, u32 count)
+{
+    uint32_t *ops_reg;
+    uint32_t *portsc;
+    u32 val, cap_length;
+    int i;
+
+    cap_length = (*(uint32_t*)xue->xhc_mmio) & 0xff;
+    ops_reg = xue->xhc_mmio + cap_length;
+
+    id--;
+    for (i = id; i < (id + count); i++) {
+        portsc = ops_reg + 0x100 + i * 0x4;
+        val = *portsc;
+        if (!(val & PORT_CONNECT))
+            *portsc = val | PORT_RESET;
+    }
+}
+
+
+static inline void xue_reset_debug_port(struct xue *xue)
+{
+    u32 val, port_offset, port_count;
+    uint32_t *xcap;
+    uint32_t next;
+    uint32_t id;
+    uint8_t *mmio = (uint8_t *)xue->xhc_mmio;
+    uint32_t *hccp1 = (uint32_t *)(mmio + 0x10);
+    const uint32_t PROTOCOL_ID = 0x2;
+
+    /**
+     * Paranoid check against a zero value. The spec mandates that
+     * at least one "supported protocol" capability must be implemented,
+     * so this should always be false.
+     */
+    if ((*hccp1 & 0xFFFF0000) == 0) {
+        return;
+    }
+
+    xcap = (uint32_t *)(mmio + (((*hccp1 & 0xFFFF0000) >> 16) << 2));
+    next = (*xcap & 0xFF00) >> 8;
+    id = *xcap & 0xFF;
+
+    /* Look for "supported protocol" capability, major revision 3 */
+    for (;next; xcap += next, id = *xcap & 0xFF, next = (*xcap & 0xFF00) >> 8) {
+        if (id != PROTOCOL_ID && next)
+            continue;
+
+        if (XUE_XHC_EXT_PORT_MAJOR(*xcap) != 0x3)
+            continue;
+
+        /* extract ports offset and count from the capability structure */
+        val = *(xcap + 2);
+        port_offset = val & 0xff;
+        port_count = (val >> 8) & 0xff;
+
+        /* and reset them all */
+        xue_do_reset_debug_port(xue, port_offset, port_count);
+    }
+}
+
 static inline void xue_dump(struct xue *xue)
 {
     struct xue_ops *op = xue->ops;
@@ -1459,6 +1524,10 @@  static inline void xue_enable_dbc(struct xue *xue)
         ops->pause(sys);
     }
 
+    /* reset ports on initial open, to force re-enumerating by the host */
+    if (!xue->open)
+        xue_reset_debug_port(xue);
+
     ops->sfence(sys);
     reg->portsc |= (1UL << XUE_PSC_PED);
     ops->sfence(sys);