From 0d970a6d25ca042049d52a4e8eae9b05c32b45ed Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Fri, 23 May 2025 10:13:54 -0400
Subject: [PATCH] XHCI: allocate scratchpad buffers

---
 src/hulk/usb/xhci.d | 38 ++++++++++++++++++++++++--------------
 1 file changed, 24 insertions(+), 14 deletions(-)

diff --git a/src/hulk/usb/xhci.d b/src/hulk/usb/xhci.d
index 013ab35..2226df8 100644
--- a/src/hulk/usb/xhci.d
+++ b/src/hulk/usb/xhci.d
@@ -47,6 +47,11 @@ struct XHCI
          */
         Volatile!uint hcs_params1;
 
+        @property ubyte max_slots()
+        {
+            return this.hcs_params1 & 0xFFu;
+        }
+
         /**
          * 3:0 isochronous scheduling threshold (IST)
          * 7:4 event ring segment table max (ERST Max)
@@ -57,6 +62,12 @@ struct XHCI
          */
         Volatile!uint hcs_params2;
 
+        @property size_t max_scratchpad_buffers()
+        {
+            uint v = this.hcs_params2;
+            return (v >> 27u) | ((v >> (21 - 5)) & 0x3E0u);
+        }
+
         /**
          * 7:0 U1 device exit latency
          * 15:8 reserved
@@ -118,11 +129,6 @@ struct XHCI
          * 31:12 VTIO register space offset (xHCI v1.2+)
          */
         Volatile!uint vtios_offset;
-
-        @property ubyte max_slots()
-        {
-            return this.hcs_params1 & 0xFFu;
-        }
     }
     static assert(CapabilityRegisters.sizeof == 0x24u);
 
@@ -370,17 +376,14 @@ struct XHCI
         ubyte * page = cast(ubyte *)Hippo.allocate_page();
         /* Device Context Index: 2K */
         void ** device_context_index = cast(void **)page;
-        page = cast(ubyte *)Hippo.allocate_page();
         /* Input Control Context: 64 bytes */
-        void * input_control_context = page;
+        void * input_control_context = &page[2048];
         /* Slot Context: 64 bytes */
-        void * slot_context = &page[64];
+        void * slot_context = &page[2048 + 64];
         /* Endpoint Context: 64 bytes */
-        void * endpoint_context = &page[128];
+        void * endpoint_context = &page[2048 + 64 + 64];
         /* Stream Context: 16 bytes */
-        void * stream_context = &page[192];
-        /* Scratchpad Buffer Array: 248 bytes */
-        void ** scratchpad_buffer_array = cast(void **)&page[256];
+        void * stream_context = &page[2048 + 64 + 64 + 64];
         /* Stream Array (Linear): 1M */
         void * stream_array_linear = Hippo.allocate_aligned_region(1024 * 1024, PAGE_SIZE);
         /* Stream Array (Pri/Sec): 4K */
@@ -393,8 +396,15 @@ struct XHCI
         void * event_ring_segments = Hippo.allocate_aligned_region(64 * 1024, 64 * 1024);
         /* Event Ring Segment Table: 512K */
         void * event_ring_segment_table = Hippo.allocate_aligned_region(512 * 1024, PAGE_SIZE);
-        /* Scratchpad Buffers: 4K */
-        void * scratchpad_buffers = Hippo.allocate_page();
+        /* Scratchpad Buffer Array: 248 bytes */
+        void ** scratchpad_buffer_array = cast(void **)Hippo.allocate_aligned_region(2 * PAGE_SIZE, PAGE_SIZE);
+
+        size_t n_scratchpad_buffers = m_capability_registers.max_scratchpad_buffers;
+        for (size_t i = 0u; i < n_scratchpad_buffers; i++)
+        {
+            void * scratchpad_buffer = Hippo.allocate_page();
+            scratchpad_buffer_array[i] = scratchpad_buffer;
+        }
 
         device_context_index[0] = scratchpad_buffer_array;