kernel/iec_listener.c

@@ -108,26 +108,16 @@ static void emit_record(u8 kind, u8 value, u8 flags)
 
 /* --- busy-poll helper ---------------------------------------------------- */
 /*
- * Spin until CLK reaches `want_asserted`, or timeout/ATN-change/RESET. Caller
+ * Spin until CLK reaches `want_asserted`, or timeout/ATN/RESET. Caller holds
- * holds local IRQs disabled. Uses a microsecond budget rather than a fixed
+ * local IRQs disabled. Uses a microsecond budget rather than a fixed udelay so
- * udelay so a slightly-fast C64 is handled correctly (research §1.3).
+ * a slightly-fast C64 is handled correctly (research §1.3).
- *
- * The ATN abort is phase-relative, and IEC_RX_ATN means "ATN changed, abort":
- *   - data_phase: ATN is released; abort if it ASSERTS (C64 interrupts data
- *     transfer with a new command).
- *   - command phase: ATN is asserted for the whole command byte; abort if it
- *     RELEASES (the command sequence is over -> hand back to the state machine).
- * Treating any asserted ATN as an abort (the previous behaviour) made command
- * reception impossible: ATN is legitimately low the entire command phase, so
- * the very first poll aborted before a single bit was clocked.
  */
-static enum iec_rx wait_clk(bool want_asserted, unsigned int timeout_us,
+static enum iec_rx wait_clk(bool want_asserted, unsigned int timeout_us)
-			    bool data_phase)
 {
 	unsigned int waited = 0;
 
 	while (iec_clk_asserted() != want_asserted) {
-		if (iec_atn_asserted() == data_phase)
+		if (iec_atn_asserted())
 			return IEC_RX_ATN;
 		if (iec_reset_asserted())
 			return IEC_RX_RESET;
@@ -153,7 +143,7 @@ static enum iec_rx receive_byte(u8 *out, bool *eoi, bool data_phase)
 	*eoi = false;
 
 	/* 1. READY-FOR-DATA: wait for talker to release CLK, then release DATA */
-	rc = wait_clk(false /* released */, IEC_CLK_TIMEOUT_US, data_phase);
+	rc = wait_clk(false /* released */, IEC_CLK_TIMEOUT_US);
 	if (rc != IEC_RX_OK)
 		return rc;
 	iec_data_release();
@@ -181,12 +171,10 @@ static enum iec_rx receive_byte(u8 *out, bool *eoi, bool data_phase)
 
 	/* 3. RECEIVE 8 BITS, LSB first */
 	for (i = 0; i < 8; i++) {
-		rc = wait_clk(true /* asserted: data invalid/setup */,
+		rc = wait_clk(true /* asserted: data invalid/setup */, IEC_CLK_TIMEOUT_US);
-			      IEC_CLK_TIMEOUT_US, data_phase);
 		if (rc != IEC_RX_OK)
 			goto out;
-		rc = wait_clk(false /* released: data valid -> sample */,
+		rc = wait_clk(false /* released: data valid -> sample */, IEC_CLK_TIMEOUT_US);
-			      IEC_CLK_TIMEOUT_US, data_phase);
 		if (rc != IEC_RX_OK)
 			goto out;
 		/* released(high) = bit 1, asserted(low) = bit 0 */