[PATCH v2 2/9] xue: reset XHCI ports when initializing dbc

["Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>]

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 <marmarek@invisiblethingslab.com>
---
Changes in v2:
- use uint32_t instead of u32
- code style
---
 xen/drivers/char/xue.c | 70 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 70 insertions(+)

diff --git a/xen/drivers/char/xue.c b/xen/drivers/char/xue.c
index 234b07b563bb..2cbbaea11fa0 100644
--- a/xen/drivers/char/xue.c
+++ b/xen/drivers/char/xue.c
@@ -63,6 +63,10 @@
     ((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)
+
 #define xue_debug(...) printk("xue debug: " __VA_ARGS__)
 #define xue_alert(...) printk("xue alert: " __VA_ARGS__)
 #define xue_error(...) printk("xue error: " __VA_ARGS__)
@@ -590,6 +594,68 @@ static void xue_init_strings(struct xue *xue, uint32_t *info)
     info[8] = (4 << 24) | (30 << 16) | (8 << 8) | 6;
 }
 
+static void xue_do_reset_debug_port(struct xue *xue,
+                                    unsigned int id, unsigned int count)
+{
+    uint32_t *ops_reg;
+    uint32_t *portsc;
+    uint32_t 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 void xue_reset_debug_port(struct xue *xue)
+{
+    uint32_t 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 void xue_enable_dbc(struct xue *xue)
 {
     struct xue_dbc_reg *reg = xue->dbc_reg;
@@ -601,6 +667,10 @@ static void xue_enable_dbc(struct xue *xue)
     while ( (reg->ctrl & (1UL << XUE_CTRL_DCE)) == 0 )
         xue_sys_pause();
 
+    /* reset ports on initial open, to force re-enumerating by the host */
+    if ( !xue->open )
+        xue_reset_debug_port(xue);
+
     wmb();
     reg->portsc |= (1UL << XUE_PSC_PED);
     wmb();
-- 
git-series 0.9.1