/*
* Device driver for the via ADB on (many) Mac II-class machines
*
* Based on the original ADB keyboard handler Copyright (c) 1997 Alan Cox
* Also derived from code Copyright (C) 1996 Paul Mackerras.
*
* With various updates provided over the years by Michael Schmitz,
* Guideo Koerber and others.
*
* Rewrite for Unified ADB by Joshua M. Thompson (funaho@jurai.org)
*
* 1999-08-02 (jmt) - Initial rewrite for Unified ADB.
* 2000-03-29 Tony Mantler <tonym@mac.linux-m68k.org>
* - Big overhaul, should actually work now.
* 2006-12-31 Finn Thain <fthain@telegraphics.com.au> - Another overhaul.
*
* Suggested reading:
* Inside Macintosh, ch. 5 ADB Manager
* Guide to the Macinstosh Family Hardware, ch. 8 Apple Desktop Bus
* Rockwell R6522 VIA datasheet
*
* Apple's "ADB Analyzer" bus sniffer is invaluable:
* ftp://ftp.apple.com/developer/Tool_Chest/Devices_-_Hardware/Apple_Desktop_Bus/
*/
#include <stdarg.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/adb.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <asm/macintosh.h>
#include <asm/macints.h>
#include <asm/mac_via.h>
static volatile unsigned char *via;
/* VIA registers - spaced 0x200 bytes apart */
#define RS 0x200 /* skip between registers */
#define B 0 /* B-side data */
#define A RS /* A-side data */
#define DIRB (2*RS) /* B-side direction (1=output) */
#define DIRA (3*RS) /* A-side direction (1=output) */
#define T1CL (4*RS) /* Timer 1 ctr/latch (low 8 bits) */
#define T1CH (5*RS) /* Timer 1 counter (high 8 bits) */
#define T1LL (6*RS) /* Timer 1 latch (low 8 bits) */
#define T1LH (7*RS) /* Timer 1 latch (high 8 bits) */
#define T2CL (8*RS) /* Timer 2 ctr/latch (low 8 bits) */
#define T2CH (9*RS) /* Timer 2 counter (high 8 bits) */
#define SR (10*RS) /* Shift register */
#define ACR (11*RS) /* Auxiliary control register */
#define PCR (12*RS) /* Peripheral control register */
#define IFR (13*RS) /* Interrupt flag register */
#define IER (14*RS) /* Interrupt enable register */
#define ANH (15*RS) /* A-side data, no handshake */
/* Bits in B data register: all active low */
#define CTLR_IRQ 0x08 /* Controller rcv status (input) */
#define ST_MASK 0x30 /* mask for selecting ADB state bits */
/* Bits in ACR */
#define SR_CTRL 0x1c /* Shift register control bits */
#define SR_EXT 0x0c /* Shift on external clock */
#define SR_OUT 0x10 /* Shift out if 1 */
/* Bits in IFR and IER */
#define IER_SET 0x80 /* set bits in IER */
#define IER_CLR 0 /* clear bits in IER */
#define SR_INT 0x04 /* Shift register full/empty */
/* ADB transaction states according to GMHW */
#define ST_CMD 0x00 /* ADB state: command byte */
#define ST_EVEN 0x10 /* ADB state: even data byte */
#define ST_ODD 0x20 /* ADB state: odd data byte */
#define ST_IDLE 0x30 /* ADB state: idle, nothing to send */
static int macii_init_via(void);
static void macii_start(void);
static irqreturn_t macii_interrupt(int irq, void *arg);
static void macii_queue_poll(void);
static int macii_probe(void);
static int macii_init(void);
static int macii_send_request(struct adb_request *req, int sync);
static int macii_write(struct adb_request *req);
static int macii_autopoll(int devs);
static void macii_poll(void);
static int macii_reset_bus(void);
struct adb_driver via_macii_driver = {
"Mac II",
macii_probe,
macii_init,
macii_send_request,
macii_autopoll,
macii_poll,
macii_reset_bus
};
static enum macii_state {
idle,
sending,
reading,
read_done,
} macii_state;
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 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 int command_byte; /* the most recent command byte transmitted */
static int autopoll_devs; /* bits set are device addresses to be polled */
/* Sanity check for request queue. Doesn't check for cycles. */
static int request_is_queued(struct adb_request *req) {
struct adb_request *cur;
unsigned long flags;
local_irq_save(flags);
cur = current_req;
while (cur) {
if (cur == req) {
local_irq_restore(flags);
return 1;
}
cur = cur->next;
}
local_irq_restore(flags);
return 0;
}
/* Check for MacII style ADB */
static int macii_probe(void)
{
if (macintosh_config->adb_type != MAC_ADB_II) return -ENODEV;
via = via1;
printk("adb: Mac II ADB Driver v1.0 for Unified ADB\n");
return 0;
}
/* Initialize the driver */
int macii_init(void)
{
unsigned long flags;
int err;
local_irq_save(flags);
err = macii_init_via();
if (err) goto out;
err = request_irq(IRQ_MAC_ADB, macii_interrupt, 0, "ADB",
macii_interrupt);
if (err) goto out;
macii_state = idle;
out:
local_irq_restore(flags);
return err;
}
/* initialize the hardware */
static int macii_init_via(void)
{
unsigned char x;
/* We want CTLR_IRQ as input and ST_EVEN | ST_ODD as output lines. */
via[DIRB] = (via[DIRB] | ST_EVEN | ST_ODD) & ~CTLR_IRQ;
/* 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;
/* Wipe any pending data and int */
x = via[SR];
return 0;
}
/* 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;
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;
BUG_ON(request_is_queued(&req));
adb_request(&req, NULL, ADBREQ_NOSEND, 1,
ADB_READREG(next_device, 0));
req.sent = 0;
req.complete = 0;
req.reply_len = 0;
req.next = current_req;
if (current_req != NULL) {
current_req = &req;
} else {
current_req = &req;
last_req = &req;
}
}
/* Send an ADB request; if sync, poll out the reply 'till it's done */
static int macii_send_request(struct adb_request *req, int sync)
{
int err;
unsigned long flags;
BUG_ON(request_is_queued(req));
local_irq_save(flags);
err = macii_write(req);
local_irq_restore(flags);
if (!err && sync) {
while (!req->complete) {
macii_poll();
}
BUG_ON(request_is_queued(req));
}
return err;
}
/* Send an ADB request (append to request queue) */
static int macii_write(struct adb_request *req)
{
if (req->nbytes < 2 || req->data[0] != ADB_PACKET || req->nbytes > 15) {
req->complete = 1;
return -EINVAL;
}
req->next = NULL;
req->sent = 0;
req->complete = 0;
req->reply_len = 0;
if (current_req != NULL) {
last_req->next = req;
last_req = req;
} else {
current_req = req;
last_req = req;
if (macii_state == idle) macii_start();
}
return 0;
}
/* Start auto-polling */
static int macii_autopoll(int devs)
{
static struct adb_request req;
unsigned long flags;
int err = 0;
/* bit 1 == device 1, and so on. */
autopoll_devs = devs & 0xFFFE;
if (!autopoll_devs) return 0;
local_irq_save(flags);
if (current_req == NULL) {
/* 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);
}
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;
}
/* Prod the chip without interrupts */
static void macii_poll(void)
{
disable_irq(IRQ_MAC_ADB);
macii_interrupt(0, NULL);
enable_irq(IRQ_MAC_ADB);
}
/* Reset the bus */
static int macii_reset_bus(void)
{
static struct adb_request req;
if (request_is_queued(&req))
return 0;
/* Command = 0, Address = ignored */
adb_request(&req, NULL, 0, 1, ADB_BUSRESET);
/* Don't want any more requests during the Global Reset low time. */
udelay(3000);
return 0;
}
/* Start sending ADB packet */
static void macii_start(void)
{
struct adb_request *req;
req = current_req;
BUG_ON(req == NULL);
BUG_ON(macii_state != idle);
/* Now send it. Be careful though, that first byte of the request
* is actually ADB_PACKET; the real data begins at index 1!
* And req->nbytes is the number of bytes of real data plus one.
*/
/* store command byte */
command_byte = req->data[1];
/* Output mode */
via[ACR] |= SR_OUT;
/* Load data */
via[SR] = req->data[1];
/* set ADB state to 'command' */
via[B] = (via[B] & ~ST_MASK) | ST_CMD;
macii_state = sending;
data_index = 2;
}
/*
* The notorious ADB interrupt handler - does all of the protocol handling.
* Relies on the ADB controller sending and receiving data, thereby
* 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.)
*/
static irqreturn_t macii_interrupt(int irq, void *arg)
{
int x;
static int entered;
struct adb_request *req;
if (!arg) {
/* Clear the SR IRQ flag when polling. */
if (via[IFR] & SR_INT)
via[IFR] = SR_INT;
else
return IRQ_NONE;
}
BUG_ON(entered++);
last_status = status;
status = via[B] & (ST_MASK|CTLR_IRQ);
switch (macii_state) {
case idle:
if (reading_reply) {
reply_ptr = current_req->reply;
} else {
BUG_ON(current_req != NULL);
reply_ptr = reply_buf;
}
x = via[SR];
if ((status & CTLR_IRQ) && (x == 0xFF)) {
/* Bus timeout without SRQ sequence:
* data is "FF" while CTLR_IRQ is "H"
*/
reply_len = 0;
srq_asserted = 0;
macii_state = read_done;
} else {
macii_state = reading;
*reply_ptr = x;
reply_len = 1;
}
/* set ADB state = even for first data byte */
via[B] = (via[B] & ~ST_MASK) | ST_EVEN;
break;
case sending:
req = current_req;
if (data_index >= req->nbytes) {
req->sent = 1;
macii_state = idle;
if (req->reply_expected) {
reading_reply = 1;
} else {
req->complete = 1;
current_req = req->next;
if (req->done) (*req->done)(req);
if (current_req)
macii_start();
else
if (need_autopoll())
macii_autopoll(autopoll_devs);
}
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;
}
} 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;
}
}
break;
case reading:
x = via[SR];
BUG_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) {
macii_state = read_done;
if (!(last_status & CTLR_IRQ))
srq_asserted = 1;
}
}
if (macii_state == reading) {
BUG_ON(reply_len > 15);
reply_ptr++;
*reply_ptr = x;
reply_len++;
}
/* invert state bits, toggle ODD/EVEN */
via[B] ^= ST_MASK;
break;
case read_done:
x = via[SR];
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;
/* SRQ seen before, initiate poll now */
if (srq_asserted)
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;
break;
default:
break;
}
entered--;
return IRQ_HANDLED;
}
