via-macii.c

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/*
 * 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 ([e-mail])
 *
 * 1999-08-02 (jmt) - Initial rewrite for Unified ADB.
 */
 
#include <stdarg.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/adb.h>
#include <asm/macintosh.h>
#include <asm/macints.h>
#include <asm/machw.h>
#include <asm/mac_via.h>
#include <asm/io.h>
#include <asm/system.h>
#include <asm/init.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 TREQ		0x08		/* Transfer request (input) */
#define TACK		0x10		/* Transfer acknowledge (output) */
#define TIP		0x20		/* Transfer in progress (output) */
#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 */
#define SR_DATA		0x08		/* Shift register data */
#define SR_CLOCK	0x10		/* Shift register clock */

/* 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 void macii_interrupt(int irq, void *arg, struct pt_regs *regs);
static void macii_retransmit(int);
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,
	sent_first_byte,
	sending,
	reading,
	read_done,
	awaiting_reply
} macii_state;

static int need_poll    = 0;
static int command_byte = 0;
static int last_reply   = 0;
static int last_active  = 0;

static struct adb_request *current_req;
static struct adb_request *last_req;
static struct adb_request *retry_req;
static unsigned char reply_buf[16];
static unsigned char *reply_ptr;
static int reply_len;
static int reading_reply;
static int data_index;
static int first_byte;
static int prefix_len;
static int status = ST_IDLE|TREQ;
static int last_status;
static int driver_running = 0;

/* debug level 10 required for ADB logging (should be && debug_adb, ideally) */

/* 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 v0.4 for Unified ADB\n");
	return 0;
}

/* Initialize the driver */
int macii_init(void)
{
	unsigned long flags;
	int err;
	
	save_flags(flags);
	cli();
	
	err = macii_init_via();
	if (err) return err;

	err = request_irq(IRQ_MAC_ADB, macii_interrupt, IRQ_FLG_LOCK, "ADB",
		    macii_interrupt);
	if (err) return err;

	macii_state = idle;
	restore_flags(flags);	
	return 0;
}

/* initialize the hardware */	
static int macii_init_via(void)
{
	unsigned char x;

	/* Set the lines up. We want TREQ as input TACK|TIP as output */
	via[DIRB] = (via[DIRB] | TACK | TIP) & ~TREQ;

	/* Set up state: idle */
	via[B] |= ST_IDLE;
	last_status = via[B] & (ST_MASK|TREQ);

	/* 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, tagged on the front of the request queue) */
static void macii_queue_poll(void)
{
	static int device = 0;
	static int in_poll=0;
	static struct adb_request req;
	unsigned long flags;

	if (in_poll) printk("macii_queue_poll: double poll!\n");

	in_poll++;
	if (++device > 15) device = 1;

	adb_request(&req, NULL, ADBREQ_REPLY|ADBREQ_NOSEND, 1,
		    ADB_READREG(device, 0));

	save_flags(flags);
	cli();

	req.next = current_req;
	current_req = &req;

	restore_flags(flags);
	macii_start();
	in_poll--;
}

/* Send an ADB retransmit (Talk, appended to the request queue) */
static void macii_retransmit(int device)
{
	static int in_retransmit = 0;
	static struct adb_request rt;
	unsigned long flags;

	if (in_retransmit) printk("macii_retransmit: double retransmit!\n");

	in_retransmit++;

	adb_request(&rt, NULL, ADBREQ_REPLY|ADBREQ_NOSEND, 1,
		    ADB_READREG(device, 0));

	save_flags(flags);
	cli();

	if (current_req != NULL) {
		last_req->next = &rt;
		last_req = &rt;
	} else {
		current_req = &rt;
		last_req = &rt;
	}

	if (macii_state == idle) macii_start();

	restore_flags(flags);
	in_retransmit--;
}

/* 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 i;

	i = macii_write(req);
	if (i) return i;

	if (sync) {
		while (!req->complete) macii_poll();
	}
	return 0;
}

/* Send an ADB request */
static int macii_write(struct adb_request *req)
{
	unsigned long flags;

	if (req->nbytes < 2 || req->data[0] != ADB_PACKET) {
		req->complete = 1;
		return -EINVAL;
	}

	req->next = 0;
	req->sent = 0;
	req->complete = 0;
	req->reply_len = 0;

	save_flags(flags); cli();

	if (current_req != NULL) {
		last_req->next = req;
		last_req = req;
	} else {
		current_req = req;
		last_req = req;
		if (macii_state == idle) macii_start();
	}

	restore_flags(flags);
	return 0;
}

/* Start auto-polling */
static int macii_autopoll(int devs)
{
	/* Just ping a random default address */
	if (!(current_req || retry_req))
		macii_retransmit( (last_active < 16 && last_active > 0) ? last_active : 3);
	return 0;
}

/* Prod the chip without interrupts */
static void macii_poll(void)
{
	unsigned long flags;

	save_flags(flags); cli();
	if (via[IFR] & SR_INT) macii_interrupt(0, 0, 0);
	restore_flags(flags);
}

/* Reset the bus */
static int macii_reset_bus(void)
{
	static struct adb_request req;
	
	/* Command = 0, Address = ignored */
	adb_request(&req, NULL, 0, 1, ADB_BUSRESET);

	return 0;
}

/* Start sending ADB packet */
static void macii_start(void)
{
	unsigned long flags;
	struct adb_request *req;

	req = current_req;
	if (!req) return;

	/* assert macii_state == idle */
	if (macii_state != idle) {
		printk("macii_start: called while driver busy (%p %x %x)!\n",
			req, macii_state, (uint) via1[B] & (ST_MASK|TREQ));
		return;
	}

	save_flags(flags); cli();
	
	/* 
	 * IRQ signaled ?? (means ADB controller wants to send, or might 
	 * be end of packet if we were reading)
	 */
	if ((via[B] & TREQ) == 0) {
		/*
		 *	FIXME - we need to restart this on a timer
		 *	or a collision at boot hangs us.
		 *	Never set macii_state to idle here, or macii_start