From 751f9641395830c741780236dfa42ce9076402dc Mon Sep 17 00:00:00 2001
From: Maxim Poliakovski <maximumspatium@googlemail.com>
Date: Mon, 15 Apr 2024 14:12:49 +0200
Subject: [PATCH] athens: clean up initialization.

---
 devices/common/i2c/athens.cpp | 17 ++++++++++++-----
 devices/common/i2c/athens.h   |  7 ++++---
 2 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/devices/common/i2c/athens.cpp b/devices/common/i2c/athens.cpp
index 1cc242b..c1b9b8a 100644
--- a/devices/common/i2c/athens.cpp
+++ b/devices/common/i2c/athens.cpp
@@ -1,6 +1,6 @@
 /*
 DingusPPC - The Experimental PowerPC Macintosh emulator
-Copyright (C) 2018-22 divingkatae and maximum
+Copyright (C) 2018-24 divingkatae and maximum
                       (theweirdo)     spatium
 
 (Contact divingkatae#1017 or powermax#2286 on Discord for more info)
@@ -44,8 +44,16 @@ AthensClocks::AthensClocks(uint8_t dev_addr)
 
     this->my_addr = dev_addr;
 
-    // set up power on values
+    // This initialization is not prescribed
+    // but let's set them to acceptable values anyway
+    this->regs[AthensRegs::D2] = 2;
+    this->regs[AthensRegs::N2] = 2;
+
+    // set P2_MUX2 on power up as follows:
+    // - dot clock VCO is disabled
+    // - dot clock = reference clock / 2
     this->regs[AthensRegs::P2_MUX2] = 0x62;
+
 }
 
 void AthensClocks::start_transaction()
@@ -72,9 +80,6 @@ bool AthensClocks::send_byte(uint8_t data)
             return false; // return NACK
         }
         this->regs[this->reg_num] = data;
-        if (reg_num == 3) {
-            LOG_F(INFO, "Athens: dot clock frequency set to %d Hz", get_dot_freq());
-        }
         break;
     default:
         LOG_F(WARNING, "Athens: too much data received!");
@@ -138,5 +143,7 @@ int AthensClocks::get_dot_freq()
         break;
     }
 
+    LOG_F(INFO, "Athens: dot clock frequency set to %f Hz", out_freq);
+
     return static_cast<int>(out_freq + 0.5f);
 }
diff --git a/devices/common/i2c/athens.h b/devices/common/i2c/athens.h
index 13217c8..d828af7 100644
--- a/devices/common/i2c/athens.h
+++ b/devices/common/i2c/athens.h
@@ -1,6 +1,6 @@
 /*
 DingusPPC - The Experimental PowerPC Macintosh emulator
-Copyright (C) 2018-22 divingkatae and maximum
+Copyright (C) 2018-24 divingkatae and maximum
                       (theweirdo)     spatium
 
 (Contact divingkatae#1017 or powermax#2286 on Discord for more info)
@@ -31,7 +31,8 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 #define ATHENS_NUM_REGS 8
 
-constexpr auto ATHENS_XTAL = 31334400.0f; // external crystal oscillator frequency
+/** Default external crystal oscillator frequency. */
+constexpr auto ATHENS_XTAL = 31334400.0f;
 
 namespace AthensRegs {
 
@@ -69,7 +70,7 @@ private:
     uint8_t     reg_num = 0;
     int         pos = 0;
 
-    uint8_t     regs[ATHENS_NUM_REGS];
+    uint8_t     regs[ATHENS_NUM_REGS] = {};
 };
 
 #endif // ATHENS_H