Finalize xHCI and USB modules

Scratchpad buffers allocation added to xHCI. Missing initialization steps
for keyboards - set configuration and set idle - added to USB. (Even
though they are specific to HID protocol, they go through USB command
endpoint, and with current module contents it's cleaner to have them
in USB module.)

README.md

@@ -1 +0,0 @@
-![It works!](./WATCHME.png)

src/kernel/fat16.c

@@ -357,7 +357,7 @@ fs_node_t *fat16_open_at(const fs_node_t *directory, uint16_t index, uint64_t fl
     ei++;
   }
 
-  fs_node_t *result = ei < entries_count ? open_entry(dir_cluster, entries, ei) : NUL;
+  fs_node_t *result = open_entry(dir_cluster, entries, ei);
 
   memory_free(entries);
 

src/kernel/xhci.c

@@ -538,7 +538,7 @@ uint64_t xhci_control_transfer(xhci_slot_t slot, uint64_t setup, void *data, uin
 }
 
 xhci_endpoint_t xhci_open_endpoint(xhci_slot_t slot, uint8_t address, uint8_t type, uint16_t max_packet_size, uint8_t interval) {
-  LOG_LN_STEP("Opening endpoint slot %d address %hhx...", slot, address);
+  LOG_LN_INFO("Opening endpoint slot %d address %hhx...", slot, address);
 
   ASSERT(slot < MAX_SLOTS, "xhci_control_transfer: Slot does not exist.");
   ASSERT(tsf_r_attached_slot == slot, "xhci_open_endpoint: Slot is not attached.");
@@ -549,11 +549,11 @@ xhci_endpoint_t xhci_open_endpoint(xhci_slot_t slot, uint8_t address, uint8_t ty
   uint8_t ep_dir = (address >> 7) & 1;
   uint8_t dci = ep_num * 2 + ep_dir;
 
-  LOG_LN_STEP("Setting up endpoint ring...");
+  LOG_LN_INFO("Setting up endpoint ring...");
   RING_WRAP(ep);
   XHCI_TRB_CYCLE_W(&ep_r[RING_LENGTH], ep_r_cycle);
 
-  LOG_LN_STEP("Configuring endpoint...");
+  LOG_LN_INFO("Configuring endpoint...");
   memory_set(0, sizeof(xhci_input_ctx_t), &input_ctx);
   input_ctx.slot = device_ctx.slot;
   input_ctx.control.add_flags = (1 << 0) | (1 << dci);
@@ -597,10 +597,9 @@ uint16_t xhci_read_endpoint(xhci_slot_t slot, xhci_endpoint_t endpoint, uint16_t
       XHCI_TRB_TRB_TYPE_W(ere, XHCI_TRB_TYPE_TRANSFER_NORMAL);
       XHCI_TRB_IOC_W(ere, 1);
       XHCI_TRB_CYCLE_W(ere, ep_r_cycle);
+      RING_ADVANCE(ep);
     }
 
-    ep_r_cycle ^= 1;
-
     db_regs[tsf_r_attached_slot] = ep_r_attached_endpoint;
 
     return 0;
@@ -608,14 +607,6 @@ uint16_t xhci_read_endpoint(xhci_slot_t slot, xhci_endpoint_t endpoint, uint16_t
 
   uint16_t transferred = 0;
   while (XHCI_TRB_CYCLE_R(&evt_r[evt_r_i]) == evt_r_cycle && !transferred) {
-    if (ep_processed_events == 0) {
-      // A bit of a hack: flip link TRB cycle only after the first event is processed. There is some delay between controller
-      // posting the last success event of the batch, and consuming the link TRB. Flipping the link cycle together with the batch
-      // might happen before the controller got a chance to check the link cycle, and stall the consumption. If we received the
-      // first event of the next batch, we're certain the link TRB has just been processed, and there's plenty of time before the next loop.
-      XHCI_TRB_CYCLE_W(&ep_r[RING_LENGTH], !ep_r_cycle);
-    }
-
     xhci_trb_t *cmp = &evt_r[evt_r_i];
 
     if (XHCI_TRB_TRB_TYPE_R(cmp) != XHCI_TRB_TYPE_EVENT_TRANSFER_COMPLETION) {
@@ -657,7 +648,7 @@ uint16_t xhci_read_endpoint(xhci_slot_t slot, xhci_endpoint_t endpoint, uint16_t
 }
 
 void xhci_close_endpoint(xhci_slot_t slot, xhci_endpoint_t endpoint) {
-  LOG_LN_STEP("Closing endpoind %hhx...", endpoint);
+  LOG_LN_INFO("Closing endpoind %hhx...", endpoint);
 
   ASSERT(slot < MAX_SLOTS, "xhci_control_transfer: Slot does not exist.");
   ASSERT(tsf_r_attached_slot == slot, "xhci_close_endpoint: Slot is not attached.");

src/user/app/rm/rm.c

@@ -10,7 +10,8 @@ exit_code_t main(uint64_t argc, const char **argv) {
 
   uint64_t code = EXIT_CODE_OK;
   for (uint64_t i = 1; i < argc; i++) {
-    if (remove(argv[i]) == (uint64_t)-1) {
+    uint64_t removed = remove(argv[i]);
+    if (removed == (uint64_t)-1) {
       ERR_S("rm: could not remove file\n");
       code = EXIT_CODE_GENERAL_FAILURE;
     }

src/user/app/shell/shell.c

@@ -96,12 +96,7 @@ static void execute(char *command) {
   uint8_t pids_count = 0;
 
   for (uint8_t i = 0; i < subcommands_count; i++) {
-    if (!string_trim(subcommands[i], ' ', &subcommands[i])) {
-      if (subcommands_count > 1) {
-        ERR_S("Syntax error.\n");
-      }
-      break;
-    }
+    string_trim(subcommands[i], ' ', &subcommands[i]);
 
     char *argv[16];
     uint8_t argc = (uint8_t)string_split(subcommands[i], ' ', 16, argv);
@@ -171,7 +166,7 @@ exit_code_t main() {
   print_prompt();
 
   char line[256];
-  uint64_t offset = 0;
+  uint64_t offset;
 
   char chunk[64];
   uint64_t received;