[PATCH 0/9] Macintosh II ADB driver fixes

@@ -110,7 +110,6 @@ static enum macii_state {
 	idle,
 	sending,
 	reading,
-	read_done,
 } macii_state;
 
 static struct adb_request *current_req; /* first request struct in the queue */

@@ -411,8 +410,8 @@ static irqreturn_t macii_interrupt(int irq, void *arg)
 			reply_len = 1;
 		} else {
 			/* bus timeout */
-			macii_state = read_done;
 			reply_len = 0;
+			break;
 		}
 
 		/* set ADB state = even for first data byte */

@@ -471,20 +470,6 @@ static irqreturn_t macii_interrupt(int irq, void *arg)
 				current_req = req->next;
 				if (req->done)
 					(*req->done)(req);
-
-				if (!current_req)
-					macii_queue_poll();
-
-				if (current_req && macii_state == idle)
-					macii_start();
-
-				if (macii_state == idle) {
-					/* reset to shift in */
-					via[ACR] &= ~SR_OUT;
-					x = via[SR];
-					/* set ADB state idle - might get SRQ */
-					via[B] = (via[B] & ~ST_MASK) | ST_IDLE;
-				}
 				break;
 			}
 		} else {

@@ -511,12 +496,28 @@ static irqreturn_t macii_interrupt(int irq, void *arg)
 			} else if (status == ST_ODD && reply_len == 2) {
 				srq_asserted = true;
 			} else {
-				macii_state = read_done;
+				macii_state = idle;
+
+				if (bus_timeout)
+					reply_len = 0;
+
+				if (reading_reply) {
+					struct adb_request *req = current_req;
+
+					req->reply_len = reply_len;
+
+					req->complete = 1;
+					current_req = req->next;
+					if (req->done)
+						(*req->done)(req);
+				} else if (reply_len && autopoll_devs) {
+					adb_input(reply_buf, reply_len, 0);
+				}
+				break;
 			}
 		}
 
-		if (macii_state == reading &&
-		    reply_len < ARRAY_SIZE(reply_buf)) {
+		if (reply_len < ARRAY_SIZE(reply_buf)) {
 			reply_ptr++;
 			*reply_ptr = x;
 			reply_len++;

@@ -526,37 +527,22 @@ static irqreturn_t macii_interrupt(int irq, void *arg)
 		via[B] ^= ST_MASK;
 		break;
 
-	case read_done:
-		x = via[SR];
-
-		if (bus_timeout)
-			reply_len = 0;
-
-		if (reading_reply) {
-			reading_reply = 0;
-			req = current_req;
-			req->reply_len = reply_len;
-			req->complete = 1;
-			current_req = req->next;
-			if (req->done)
-				(*req->done)(req);
-		} else if (reply_len && autopoll_devs)
-			adb_input(reply_buf, reply_len, 0);
-
-		macii_state = idle;
+	default:
+		break;
+	}
 
+	if (macii_state == idle) {
 		if (!current_req)
 			macii_queue_poll();
 
 		if (current_req)
 			macii_start();
 
-		if (macii_state == idle)
+		if (macii_state == idle) {
+			via[ACR] &= ~SR_OUT;
+			x = via[SR];
 			via[B] = (via[B] & ~ST_MASK) | ST_IDLE;
-		break;
-
-	default:
-		break;
+		}
 	}
 
 	local_irq_restore(flags);

@@ -77,6 +77,10 @@ static volatile unsigned char *via;
 #define ST_ODD		0x20		/* ADB state: odd data byte */
 #define ST_IDLE		0x30		/* ADB state: idle, nothing to send */
 
+/* ADB command byte structure */
+#define ADDR_MASK	0xF0
+#define CMD_MASK	0x0F
+
 static int macii_init_via(void);
 static void macii_start(void);
 static irqreturn_t macii_interrupt(int irq, void *arg);

@@ -117,7 +121,8 @@ static int reply_len; /* number of bytes received in reply_buf or req->reply */
 static int status;          /* VIA's ADB status bits captured upon interrupt */
 static int last_status;              /* status bits as at previous interrupt */
 static int srq_asserted;     /* have to poll for the device that asserted it */
-static int command_byte;         /* the most recent command byte transmitted */
+static u8 last_cmd;              /* the most recent command byte transmitted */
+static u8 last_poll_cmd; /* the most recent Talk R0 command byte transmitted */
 static int autopoll_devs;      /* bits set are device addresses to be polled */
 
 /* Check for MacII style ADB */

@@ -179,35 +184,49 @@ static int macii_init_via(void)
 /* Send an ADB poll (Talk Register 0 command prepended to the request queue) */
 static void macii_queue_poll(void)
 {
-	/* No point polling the active device as it will never assert SRQ, so
-	 * poll the next device in the autopoll list. This could leave us
-	 * stuck in a polling loop if an unprobed device is asserting SRQ.
-	 * In theory, that could only happen if a device was plugged in after
-	 * probing started. Unplugging it again will break the cycle.
-	 * (Simply polling the next higher device often ends up polling almost
-	 * every device (after wrapping around), which takes too long.)
-	 */
-	int device_mask;
-	int next_device;
 	static struct adb_request req;
+	unsigned char poll_command;
+	unsigned int poll_addr;
 
+	/* This only polls devices in the autopoll list, which assumes that
+	 * unprobed devices never assert SRQ. That could happen if a device was
+	 * plugged in after the adb bus scan. Unplugging it again will resolve
+	 * the problem. This behaviour is similar to MacOS.
+	 */
 	if (!autopoll_devs)
 		return;
 
-	device_mask = (1 << (((command_byte & 0xF0) >> 4) + 1)) - 1;
-	if (autopoll_devs & ~device_mask)
-		next_device = ffs(autopoll_devs & ~device_mask) - 1;
-	else
-		next_device = ffs(autopoll_devs) - 1;
+	/* The device most recently polled may not be the best device to poll
+	 * right now. Some other device(s) may have signalled SRQ (the active
+	 * device won't do that). Or the autopoll list may have been changed.
+	 * Try polling the next higher address.
+	 */
+	poll_addr = (last_poll_cmd & ADDR_MASK) >> 4;
+	if ((srq_asserted && last_cmd == last_poll_cmd) ||
+	    !(autopoll_devs & (1 << poll_addr))) {
+		unsigned int higher_devs;
+
+		higher_devs = autopoll_devs & -(1 << (poll_addr + 1));
+		poll_addr = ffs(higher_devs ? higher_devs : autopoll_devs) - 1;
+	}
 
-	adb_request(&req, NULL, ADBREQ_NOSEND, 1, ADB_READREG(next_device, 0));
+	/* Send a Talk Register 0 command */
+	poll_command = ADB_READREG(poll_addr, 0);
+
+	/* No need to repeat this Talk command. The transceiver will do that
+	 * as long as it is idle.
+	 */
+	if (poll_command == last_cmd)
+		return;
+
+	adb_request(&req, NULL, ADBREQ_NOSEND, 1, poll_command);
 
 	req.sent = 0;
 	req.complete = 0;
 	req.reply_len = 0;
 	req.next = current_req;
 
-	if (current_req != NULL) {
+	if (WARN_ON(current_req)) {
 		current_req = &req;
 	} else {
 		current_req = &req;

@@ -266,37 +285,22 @@ static int macii_write(struct adb_request *req)
 /* Start auto-polling */
 static int macii_autopoll(int devs)
 {
-	static struct adb_request req;
 	unsigned long flags;
-	int err = 0;
 
 	local_irq_save(flags);
 
 	/* bit 1 == device 1, and so on. */
 	autopoll_devs = devs & 0xFFFE;
 
-	if (autopoll_devs && !current_req) {
-		/* Send a Talk Reg 0. The controller will repeatedly transmit
-		 * this as long as it is idle.
-		 */
-		adb_request(&req, NULL, ADBREQ_NOSEND, 1,
-		            ADB_READREG(ffs(autopoll_devs) - 1, 0));
-		err = macii_write(&req);
+	if (!current_req) {
+		macii_queue_poll();
+		if (current_req && macii_state == idle)
+			macii_start();
 	}
 
 	local_irq_restore(flags);
-	return err;
-}
 
-static inline int need_autopoll(void)
-{
-	/* Was the last command Talk Reg 0
-	 * and is the target on the autopoll list?
-	 */
-	if ((command_byte & 0x0F) == 0x0C &&
-	    ((1 << ((command_byte & 0xF0) >> 4)) & autopoll_devs))
-		return 0;
-	return 1;
+	return 0;
 }
 
 /* Prod the chip without interrupts */

@@ -333,7 +337,12 @@ static void macii_start(void)
 	 */
 
 	/* store command byte */
-	command_byte = req->data[1];
+	last_cmd = req->data[1];
+
+	/* If this is a Talk Register 0 command, store the command byte */
+	if ((last_cmd & CMD_MASK) == ADB_READREG(0, 0))
+		last_poll_cmd = last_cmd;
+
 	/* Output mode */
 	via[ACR] |= SR_OUT;
 	/* Load data */

@@ -424,10 +433,11 @@ static irqreturn_t macii_interrupt(int irq, void *arg)
 				if (req->done)
 					(*req->done)(req);
 
-				if (current_req)
+				if (!current_req)
+					macii_queue_poll();
+
+				if (current_req && macii_state == idle)
 					macii_start();
-				else if (need_autopoll())
-					macii_autopoll(autopoll_devs);
 			}
 
 			if (macii_state == idle) {

@@ -507,14 +517,11 @@ static irqreturn_t macii_interrupt(int irq, void *arg)
 
 		macii_state = idle;
 
-		/* SRQ seen before, initiate poll now */
-		if (srq_asserted)
+		if (!current_req)
 			macii_queue_poll();
 
 		if (current_req)
 			macii_start();
-		else if (need_autopoll())
-			macii_autopoll(autopoll_devs);
 
 		if (macii_state == idle)
 			via[B] = (via[B] & ~ST_MASK) | ST_IDLE;

@@ -313,7 +313,7 @@ static void macii_poll(void)
 /* Reset the bus */
 static int macii_reset_bus(void)
 {
-	static struct adb_request req;
+	struct adb_request req;
 
 	/* Command = 0, Address = ignored */
 	adb_request(&req, NULL, ADBREQ_NOSEND, 1, ADB_BUSRESET);

@@ -125,7 +125,7 @@ static bool srq_asserted;    /* have to poll for the device that asserted it */
 static u8 last_cmd;              /* the most recent command byte transmitted */
 static u8 last_talk_cmd;    /* the most recent Talk command byte transmitted */
 static u8 last_poll_cmd; /* the most recent Talk R0 command byte transmitted */
-static int autopoll_devs;      /* bits set are device addresses to be polled */
+static unsigned int autopoll_devs;  /* bits set are device addresses to poll */
 
 /* Check for MacII style ADB */
 static int macii_probe(void)

@@ -291,7 +291,7 @@ static int macii_autopoll(int devs)
 	local_irq_save(flags);
 
 	/* bit 1 == device 1, and so on. */
-	autopoll_devs = devs & 0xFFFE;
+	autopoll_devs = (unsigned int)devs & 0xFFFE;
 
 	if (!current_req) {
 		macii_queue_poll();

@@ -140,7 +140,7 @@ static int macii_probe(void)
 }
 
 /* Initialize the driver */
-int macii_init(void)
+static int macii_init(void)
 {
 	unsigned long flags;
 	int err;

@@ -80,6 +80,8 @@ static volatile unsigned char *via;
 /* ADB command byte structure */
 #define ADDR_MASK	0xF0
 #define CMD_MASK	0x0F
+#define OP_MASK		0x0C
+#define TALK		0x0C
 
 static int macii_init_via(void);
 static void macii_start(void);

@@ -119,9 +121,10 @@ static int reading_reply;        /* store reply in reply_buf else req->reply */
 static int data_index;      /* index of the next byte to send from req->data */
 static int reply_len; /* number of bytes received in reply_buf or req->reply */
 static int status;          /* VIA's ADB status bits captured upon interrupt */
-static int last_status;              /* status bits as at previous interrupt */
-static int srq_asserted;     /* have to poll for the device that asserted it */
+static bool bus_timeout;                   /* no data was sent by the device */
+static bool srq_asserted;    /* have to poll for the device that asserted it */
 static u8 last_cmd;              /* the most recent command byte transmitted */
+static u8 last_talk_cmd;    /* the most recent Talk command byte transmitted */
 static u8 last_poll_cmd; /* the most recent Talk R0 command byte transmitted */
 static int autopoll_devs;      /* bits set are device addresses to be polled */
 

@@ -170,7 +173,6 @@ static int macii_init_via(void)
 
 	/* Set up state: idle */
 	via[B] |= ST_IDLE;
-	last_status = via[B] & (ST_MASK | CTLR_IRQ);
 
 	/* Shift register on input */
 	via[ACR] = (via[ACR] & ~SR_CTRL) | SR_EXT;

@@ -336,13 +338,6 @@ static void macii_start(void)
 	 * And req->nbytes is the number of bytes of real data plus one.
 	 */
 
-	/* store command byte */
-	last_cmd = req->data[1];
-
-	/* If this is a Talk Register 0 command, store the command byte */
-	if ((last_cmd & CMD_MASK) == ADB_READREG(0, 0))
-		last_poll_cmd = last_cmd;
-
 	/* Output mode */
 	via[ACR] |= SR_OUT;
 	/* Load data */

@@ -352,6 +347,9 @@ static void macii_start(void)
 
 	macii_state = sending;
 	data_index = 2;
+
+	bus_timeout = false;
+	srq_asserted = false;
 }
 
 /*

@@ -360,15 +358,17 @@ static void macii_start(void)
  * generating shift register interrupts (SR_INT) for us. This means there has
  * to be activity on the ADB bus. The chip will poll to achieve this.
  *
- * The basic ADB state machine was left unchanged from the original MacII code
- * by Alan Cox, which was based on the CUDA driver for PowerMac.
- * The syntax of the ADB status lines is totally different on MacII,
- * though. MacII uses the states Command -> Even -> Odd -> Even ->...-> Idle
- * for sending and Idle -> Even -> Odd -> Even ->...-> Idle for receiving.
- * Start and end of a receive packet are signalled by asserting /IRQ on the
- * interrupt line (/IRQ means the CTLR_IRQ bit in port B; not to be confused
- * with the VIA shift register interrupt. /IRQ never actually interrupts the
- * processor, it's just an ordinary input.)
+ * The VIA Port B output signalling works as follows. After the ADB transceiver
+ * sees a transition on the PB4 and PB5 lines it will crank over the VIA shift
+ * register which eventually raises the SR_INT interrupt. The PB4/PB5 outputs
+ * are toggled with each byte as the ADB transaction progresses.
+ *
+ * Request with no reply expected (and empty transceiver buffer):
+ *     CMD -> IDLE
+ * Request with expected reply packet (or with buffered autopoll packet):
+ *     CMD -> EVEN -> ODD -> EVEN -> ... -> IDLE
+ * Unsolicited packet:
+ *     IDLE -> EVEN -> ODD -> EVEN -> ... -> IDLE
  */
 static irqreturn_t macii_interrupt(int irq, void *arg)
 {

@@ -388,31 +388,31 @@ static irqreturn_t macii_interrupt(int irq, void *arg)
 		}
 	}
 
-	last_status = status;
 	status = via[B] & (ST_MASK | CTLR_IRQ);
 
 	switch (macii_state) {
 	case idle:
-		if (reading_reply) {
-			reply_ptr = current_req->reply;
-		} else {
-			WARN_ON(current_req);
-			reply_ptr = reply_buf;
-		}
+		WARN_ON((status & ST_MASK) != ST_IDLE);
+
+		reply_ptr = reply_buf;
+		reading_reply = 0;
+
+		bus_timeout = false;
+		srq_asserted = false;
 
 		x = via[SR];
 
-		if ((status & CTLR_IRQ) && (x == 0xFF)) {
-			/* Bus timeout without SRQ sequence:
-			 *     data is "FF" while CTLR_IRQ is "H"
+		if (!(status & CTLR_IRQ)) {
+			/* /CTLR_IRQ asserted in idle state means we must
+			 * read an autopoll reply from the transceiver buffer.
 			 */
-			reply_len = 0;
-			srq_asserted = 0;
-			macii_state = read_done;
-		} else {
 			macii_state = reading;
 			*reply_ptr = x;
 			reply_len = 1;
+		} else {
+			/* bus timeout */
+			macii_state = read_done;
+			reply_len = 0;
 		}
 
 		/* set ADB state = even for first data byte */

@@ -421,13 +421,52 @@ static irqreturn_t macii_interrupt(int irq, void *arg)
 
 	case sending:
 		req = current_req;
-		if (data_index >= req->nbytes) {
+
+		if (status == (ST_CMD | CTLR_IRQ)) {
+			/* /CTLR_IRQ de-asserted after the command byte means
+			 * the host can continue with the transaction.
+			 */
+
+			/* Store command byte */
+			last_cmd = req->data[1];
+			if ((last_cmd & OP_MASK) == TALK) {
+				last_talk_cmd = last_cmd;
+				if ((last_cmd & CMD_MASK) == ADB_READREG(0, 0))
+					last_poll_cmd = last_cmd;
+			}
+		}
+
+		if (status == ST_CMD) {
+			/* /CTLR_IRQ asserted after the command byte means we
+			 * must read an autopoll reply. The first byte was
+			 * lost because the shift register was an output.
+			 */
+			macii_state = reading;
+
+			reading_reply = 0;
+			reply_ptr = reply_buf;
+			*reply_ptr = last_talk_cmd;
+			reply_len = 1;
+
+			/* reset to shift in */
+			via[ACR] &= ~SR_OUT;
+			x = via[SR];
+		} else if (data_index >= req->nbytes) {
 			req->sent = 1;
-			macii_state = idle;
 
 			if (req->reply_expected) {
+				macii_state = reading;
+
 				reading_reply = 1;
+				reply_ptr = req->reply;
+				*reply_ptr = req->data[1];
+				reply_len = 1;
+
+				via[ACR] &= ~SR_OUT;
+				x = via[SR];
 			} else {
+				macii_state = idle;
+
 				req->complete = 1;
 				current_req = req->next;
 				if (req->done)

@@ -438,25 +477,26 @@ static irqreturn_t macii_interrupt(int irq, void *arg)
 
 				if (current_req && macii_state == idle)
 					macii_start();
-			}
 
-			if (macii_state == idle) {
-				/* reset to shift in */
-				via[ACR] &= ~SR_OUT;
-				x = via[SR];
-				/* set ADB state idle - might get SRQ */
-				via[B] = (via[B] & ~ST_MASK) | ST_IDLE;
+				if (macii_state == idle) {
+					/* reset to shift in */
+					via[ACR] &= ~SR_OUT;
+					x = via[SR];
+					/* set ADB state idle - might get SRQ */
+					via[B] = (via[B] & ~ST_MASK) | ST_IDLE;
+				}
+				break;
 			}
 		} else {
 			via[SR] = req->data[data_index++];
+		}
 
-			if ((via[B] & ST_MASK) == ST_CMD) {
-				/* just sent the command byte, set to EVEN */
-				via[B] = (via[B] & ~ST_MASK) | ST_EVEN;
-			} else {
-				/* invert state bits, toggle ODD/EVEN */
-				via[B] ^= ST_MASK;
-			}
+		if ((via[B] & ST_MASK) == ST_CMD) {
+			/* just sent the command byte, set to EVEN */
+			via[B] = (via[B] & ~ST_MASK) | ST_EVEN;
+		} else {
+			/* invert state bits, toggle ODD/EVEN */
+			via[B] ^= ST_MASK;
 		}
 		break;
 

@@ -465,28 +505,13 @@ static irqreturn_t macii_interrupt(int irq, void *arg)
 		WARN_ON((status & ST_MASK) == ST_CMD ||
 			(status & ST_MASK) == ST_IDLE);
 
-		/* Bus timeout with SRQ sequence:
-		 *     data is "XX FF"      while CTLR_IRQ is "L L"
-		 * End of packet without SRQ sequence:
-		 *     data is "XX...YY 00" while CTLR_IRQ is "L...H L"
-		 * End of packet SRQ sequence:
-		 *     data is "XX...YY 00" while CTLR_IRQ is "L...L L"
-		 * (where XX is the first response byte and
-		 * YY is the last byte of valid response data.)
-		 */
-
-		srq_asserted = 0;
 		if (!(status & CTLR_IRQ)) {
-			if (x == 0xFF) {
-				if (!(last_status & CTLR_IRQ)) {
-					macii_state = read_done;
-					reply_len = 0;
-					srq_asserted = 1;
-				}
-			} else if (x == 0x00) {
+			if (status == ST_EVEN && reply_len == 1) {
+				bus_timeout = true;
+			} else if (status == ST_ODD && reply_len == 2) {
+				srq_asserted = true;
+			} else {
 				macii_state = read_done;
-				if (!(last_status & CTLR_IRQ))
-					srq_asserted = 1;
 			}
 		}
 

@@ -504,6 +529,9 @@ static irqreturn_t macii_interrupt(int irq, void *arg)
 	case read_done:
 		x = via[SR];
 
+		if (bus_timeout)
+			reply_len = 0;
+
 		if (reading_reply) {
 			reading_reply = 0;
 			req = current_req;

@@ -116,7 +116,7 @@ static struct adb_request *current_req; /* first request struct in the queue */
 static struct adb_request *last_req;     /* last request struct in the queue */
 static unsigned char reply_buf[16];        /* storage for autopolled replies */
 static unsigned char *reply_ptr;     /* next byte in reply_buf or req->reply */
-static int reading_reply;        /* store reply in reply_buf else req->reply */
+static bool reading_reply;       /* store reply in reply_buf else req->reply */
 static int data_index;      /* index of the next byte to send from req->data */
 static int reply_len; /* number of bytes received in reply_buf or req->reply */
 static int status;          /* VIA's ADB status bits captured upon interrupt */

@@ -394,7 +394,7 @@ static irqreturn_t macii_interrupt(int irq, void *arg)
 		WARN_ON((status & ST_MASK) != ST_IDLE);
 
 		reply_ptr = reply_buf;
-		reading_reply = 0;
+		reading_reply = false;
 
 		bus_timeout = false;
 		srq_asserted = false;

@@ -442,7 +442,7 @@ static irqreturn_t macii_interrupt(int irq, void *arg)
 			 */
 			macii_state = reading;
 
-			reading_reply = 0;
+			reading_reply = false;
 			reply_ptr = reply_buf;
 			*reply_ptr = last_talk_cmd;
 			reply_len = 1;

@@ -456,7 +456,7 @@ static irqreturn_t macii_interrupt(int irq, void *arg)
 			if (req->reply_expected) {
 				macii_state = reading;
 
-				reading_reply = 1;
+				reading_reply = true;
 				reply_ptr = req->reply;
 				*reply_ptr = req->data[1];
 				reply_len = 1;

@@ -466,7 +466,7 @@ static irqreturn_t macii_interrupt(int irq, void *arg)
 			} else if ((req->data[1] & OP_MASK) == TALK) {
 				macii_state = reading;
 
-				reading_reply = 0;
+				reading_reply = false;
 				reply_ptr = reply_buf;
 				*reply_ptr = req->data[1];
 				reply_len = 1;

@@ -463,6 +463,21 @@ static irqreturn_t macii_interrupt(int irq, void *arg)
 
 				via[ACR] &= ~SR_OUT;
 				x = via[SR];
+			} else if ((req->data[1] & OP_MASK) == TALK) {
+				macii_state = reading;
+
+				reading_reply = 0;
+				reply_ptr = reply_buf;
+				*reply_ptr = req->data[1];
+				reply_len = 1;
+
+				via[ACR] &= ~SR_OUT;
+				x = via[SR];
+
+				req->complete = 1;
+				current_req = req->next;
+				if (req->done)
+					(*req->done)(req);
 			} else {
 				macii_state = idle;
 

@@ -510,8 +525,9 @@ static irqreturn_t macii_interrupt(int irq, void *arg)
 					current_req = req->next;
 					if (req->done)
 						(*req->done)(req);
-				} else if (reply_len && autopoll_devs) {
-					adb_input(reply_buf, reply_len, 0);
+				} else if (reply_len && autopoll_devs &&
+					   reply_buf[0] == last_poll_cmd) {
+					adb_input(reply_buf, reply_len, 1);
 				}
 				break;
 			}

@@ -270,15 +270,12 @@ static int macii_autopoll(int devs)
 	unsigned long flags;
 	int err = 0;
 
+	local_irq_save(flags);
+
 	/* bit 1 == device 1, and so on. */
 	autopoll_devs = devs & 0xFFFE;
 
-	if (!autopoll_devs)
-		return 0;
-
-	local_irq_save(flags);
-
-	if (current_req == NULL) {
+	if (autopoll_devs && !current_req) {
 		/* Send a Talk Reg 0. The controller will repeatedly transmit
 		 * this as long as it is idle.
 		 */