From c51ea575cab51eb7a8708190a5190667f3d7a763 Mon Sep 17 00:00:00 2001
From: Maxim Poliakovski <maximumspatium@googlemail.com>
Date: Tue, 25 Oct 2022 02:45:44 +0200
Subject: [PATCH] scsi_bus: various fixes and improvements.

---
 devices/common/scsi/scsi.h       | 27 +++++++++++++-----
 devices/common/scsi/scsi_bus.cpp | 49 +++++++++++++++++++++++++++++---
 2 files changed, 65 insertions(+), 11 deletions(-)

diff --git a/devices/common/scsi/scsi.h b/devices/common/scsi/scsi.h
index 24c418c..7d3a414 100644
--- a/devices/common/scsi/scsi.h
+++ b/devices/common/scsi/scsi.h
@@ -45,13 +45,19 @@ enum {
     SCSI_CTRL_RST = 1 << 8,
 };
 
-enum ScsiPhase : int {
+namespace ScsiPhase {
+enum : int {
     BUS_FREE = 0,
     ARBITRATION,
     SELECTION,
     RESELECTION,
+    COMMAND,
+    DATA,
+    STATUS,
+    MESSAGE,
     RESET,
 };
+};
 
 enum ScsiMsg : int {
     CONFIRM_SEL = 1,
@@ -143,12 +149,18 @@ public:
     ScsiBus();
     ~ScsiBus() = default;
 
-    // low-level control/status
-    void register_device(int id, ScsiDevice* dev_obj);
-    void assert_ctrl_line(int id, uint16_t mask);
-    void release_ctrl_line(int id, uint16_t mask);
-    void release_ctrl_lines(int id);
-    int  current_phase() { return this->cur_phase; };
+    // low-level state management
+    void    register_device(int id, ScsiDevice* dev_obj);
+    int     current_phase() { return this->cur_phase; };
+
+    // reading/writing control lines
+    void        assert_ctrl_line(int id, uint16_t mask);
+    void        release_ctrl_line(int id, uint16_t mask);
+    void        release_ctrl_lines(int id);
+    uint16_t    test_ctrl_lines(uint16_t mask);
+
+    // reading/writing data lines
+    uint8_t get_data_lines() { return this->data_lines; };
 
     // high-level control/status
     bool begin_arbitration(int id);
@@ -156,6 +168,7 @@ public:
     bool begin_selection(int initiator_id, int target_id, bool atn);
     void confirm_selection(int target_id);
     bool end_selection(int initiator_id, int target_id);
+    bool transfer_command(uint8_t* dst_ptr);
     void disconnect(int dev_id);
 
 protected:
diff --git a/devices/common/scsi/scsi_bus.cpp b/devices/common/scsi/scsi_bus.cpp
index a50efe3..3bb06ee 100644
--- a/devices/common/scsi/scsi_bus.cpp
+++ b/devices/common/scsi/scsi_bus.cpp
@@ -36,11 +36,11 @@ ScsiBus::ScsiBus()
         this->dev_ctrl_lines[i] = 0;
     }
 
-    this->ctrl_lines = 0; // all control lines released
-    this->data_lines = 0; // data lines released
+    this->ctrl_lines    =  0; // all control lines released
+    this->data_lines    =  0; // data lines released
     this->arb_winner_id = -1;
-    this->initiator_id = -1;
-    this->target_id = -1;
+    this->initiator_id  = -1;
+    this->target_id     = -1;
 }
 
 void ScsiBus::register_device(int id, ScsiDevice* dev_obj)
@@ -98,6 +98,8 @@ void ScsiBus::release_ctrl_line(int id, uint16_t mask)
             this->cur_phase = ScsiPhase::BUS_FREE;
             change_bus_phase(id);
         }
+    } else {
+        this->ctrl_lines = new_state;
     }
 }
 
@@ -106,6 +108,18 @@ void ScsiBus::release_ctrl_lines(int id)
     this->release_ctrl_line(id, 0xFFFFUL);
 }
 
+uint16_t ScsiBus::test_ctrl_lines(uint16_t mask)
+{
+    uint16_t new_state = 0;
+
+    // OR control lines of all devices together
+    for (int i = 0; i < SCSI_MAX_DEVS; i++) {
+        new_state |= this->dev_ctrl_lines[i];
+    }
+
+    return new_state & mask;
+}
+
 bool ScsiBus::begin_arbitration(int initiator_id)
 {
     if (this->cur_phase == ScsiPhase::BUS_FREE) {
@@ -143,6 +157,8 @@ bool ScsiBus::begin_selection(int initiator_id, int target_id, bool atn)
     if (this->cur_phase != ScsiPhase::ARBITRATION || this->arb_winner_id != initiator_id)
         return false;
 
+    this->assert_ctrl_line(initiator_id, SCSI_CTRL_SEL);
+
     this->data_lines |= (1 << initiator_id) | (1 << target_id);
 
     if (atn) {
@@ -171,6 +187,31 @@ bool ScsiBus::end_selection(int initiator_id, int target_id)
     return this->target_id == target_id;
 }
 
+bool ScsiBus::transfer_command(uint8_t* dst_ptr)
+{
+    static uint8_t cmd_to_cdb_length[8] = {6, 10, 10, 6, 6, 12, 6, 6};
+
+    this->cur_phase = ScsiPhase::COMMAND;
+    change_bus_phase(target_id);
+
+    // attempt to transfer the shortest Command Description Block (CDB)
+    if (!this->devices[this->initiator_id]->send_bytes(dst_ptr, 6)) {
+        LOG_F(ERROR, "ScsiBus: error while transferring CDB!");
+        return false;
+    }
+
+    // transfer the remaining CDB
+    int cdb_length = cmd_to_cdb_length[dst_ptr[0] >> 5];
+    if (cdb_length > 6) {
+        if (!this->devices[this->initiator_id]->send_bytes(dst_ptr + 6, cdb_length - 6)) {
+            LOG_F(ERROR, "ScsiBus: error while transferring CDB!");
+            return false;
+        }
+    }
+
+    return true;
+}
+
 void ScsiBus::disconnect(int dev_id)
 {
     this->release_ctrl_lines(dev_id);