summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
Diffstat
-rw-r--r--drivers/macintosh/via-macii.c166
1 files changed, 97 insertions, 69 deletions
diff --git a/drivers/macintosh/via-macii.c b/drivers/macintosh/via-macii.c
index d4f1a65c5f1f..6a5cd7de05ba 100644
--- a/drivers/macintosh/via-macii.c
+++ b/drivers/macintosh/via-macii.c
@@ -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;
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-28 16:49:38 +0100