macserial.c

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/*
 * macserial.c: Serial port driver for Power Macintoshes.
 *
 * Derived from drivers/sbus/char/sunserial.c by Paul Mackerras.
 *
 * Copyright (C) 1996 Paul Mackerras ([e-mail])
 * Copyright (C) 1995 David S. Miller ([e-mail])
 *
 * Receive DMA code by Takashi Oe <[e-mail]>.
 *
 * $Id: macserial.c,v 1.24.2.4 1999/10/19 04:36:42 paulus Exp $
 */

#include <linux/config.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/init.h>
#ifdef CONFIG_SERIAL_CONSOLE
#include <linux/console.h>
#endif
#include <linux/slab.h>

#include <asm/init.h>
#include <asm/io.h>
#include <asm/pgtable.h>
#include <asm/irq.h>
#include <asm/prom.h>
#include <asm/system.h>
#include <asm/segment.h>
#include <asm/bitops.h>
#include <asm/feature.h>
#include <linux/adb.h>
#include <linux/pmu.h>
#ifdef CONFIG_KGDB
#include <asm/kgdb.h>
#endif
#include <asm/dbdma.h>

#include "macserial.h"

#ifdef CONFIG_PMAC_PBOOK
static int serial_notify_sleep(struct pmu_sleep_notifier *self, int when);
static struct pmu_sleep_notifier serial_sleep_notifier = {
	serial_notify_sleep,
	SLEEP_LEVEL_MISC,
};
#endif

#define SUPPORT_SERIAL_DMA

/*
 * It would be nice to dynamically allocate everything that
 * depends on NUM_SERIAL, so we could support any number of
 * Z8530s, but for now...
 */
#define NUM_SERIAL	2		/* Max number of ZS chips supported */
#define NUM_CHANNELS	(NUM_SERIAL * 2)	/* 2 channels per chip */

/* On PowerMacs, the hardware takes care of the SCC recovery time,
   but we need the eieio to make sure that the accesses occur
   in the order we want. */
#define RECOVERY_DELAY	eieio()

struct mac_zschannel zs_channels[NUM_CHANNELS];

struct mac_serial zs_soft[NUM_CHANNELS];
int zs_channels_found;
struct mac_serial *zs_chain;	/* list of all channels */

struct tty_struct zs_ttys[NUM_CHANNELS];

static int is_powerbook;

#ifdef CONFIG_SERIAL_CONSOLE
static struct console sercons;
#endif

#ifdef CONFIG_KGDB
struct mac_zschannel *zs_kgdbchan;
static unsigned char scc_inittab[] = {
	9,  0x80,	/* reset A side (CHRA) */
	13, 0,		/* set baud rate divisor */
	12, 1,
	14, 1,		/* baud rate gen enable, src=rtxc (BRENABL) */
	11, 0x50,	/* clocks = br gen (RCBR | TCBR) */
	5,  0x6a,	/* tx 8 bits, assert RTS (Tx8 | TxENAB | RTS) */
	4,  0x44,	/* x16 clock, 1 stop (SB1 | X16CLK)*/
	3,  0xc1,	/* rx enable, 8 bits (RxENABLE | Rx8)*/
};
#endif
#define ZS_CLOCK         3686400 	/* Z8530 RTxC input clock rate */

static DECLARE_TASK_QUEUE(tq_serial);

static struct tty_driver serial_driver, callout_driver;
static int serial_refcount;

/* serial subtype definitions */
#define SERIAL_TYPE_NORMAL	1
#define SERIAL_TYPE_CALLOUT	2

/* number of characters left in xmit buffer before we ask for more */
#define WAKEUP_CHARS 256

/*
 * Debugging.
 */
#undef SERIAL_DEBUG_INTR
#undef SERIAL_DEBUG_OPEN
#undef SERIAL_DEBUG_FLOW
#undef SERIAL_DEBUG_POWER
#undef SERIAL_DEBUG_THROTTLE
#undef SERIAL_DEBUG_STOP
#undef SERIAL_DEBUG_BAUDS

#define RS_STROBE_TIME 10
#define RS_ISR_PASS_LIMIT 256

#define _INLINE_ inline

#ifdef SERIAL_DEBUG_OPEN
#define OPNDBG(fmt, arg...)	printk(KERN_DEBUG fmt , ## arg)
#else
#define OPNDBG(fmt, arg...)	do { } while (0)
#endif
#ifdef SERIAL_DEBUG_POWER
#define PWRDBG(fmt, arg...)	printk(KERN_DEBUG fmt , ## arg)
#else
#define PWRDBG(fmt, arg...)	do { } while (0)
#endif
#ifdef SERIAL_DEBUG_BAUDS
#define BAUDBG(fmt, arg...)	printk(fmt , ## arg)
#else
#define BAUDBG(fmt, arg...)	do { } while (0)
#endif

static void probe_sccs(void);
static void change_speed(struct mac_serial *info, struct termios *old);
static void rs_wait_until_sent(struct tty_struct *tty, int timeout);
static int set_scc_power(struct mac_serial * info, int state);
static int setup_scc(struct mac_serial * info);
static void dbdma_reset(volatile struct dbdma_regs *dma);
static void dbdma_flush(volatile struct dbdma_regs *dma);
static void rs_txdma_irq(int irq, void *dev_id, struct pt_regs *regs);
static void rs_rxdma_irq(int irq, void *dev_id, struct pt_regs *regs);
static void dma_init(struct mac_serial * info);
static void rxdma_start(struct mac_serial * info, int current);
static void rxdma_to_tty(struct mac_serial * info);

static struct tty_struct *serial_table[NUM_CHANNELS];
static struct termios *serial_termios[NUM_CHANNELS];
static struct termios *serial_termios_locked[NUM_CHANNELS];

#ifndef MIN
#define MIN(a,b)	((a) < (b) ? (a) : (b))
#endif

/*
 * tmp_buf is used as a temporary buffer by serial_write.  We need to
 * lock it in case the copy_from_user blocks while swapping in a page,
 * and some other program tries to do a serial write at the same time.
 * Since the lock will only come under contention when the system is
 * swapping and available memory is low, it makes sense to share one
 * buffer across all the serial ports, since it significantly saves
 * memory if large numbers of serial ports are open.
 */
static unsigned char *tmp_buf;
static DECLARE_MUTEX(tmp_buf_sem);


static inline int __pmac
serial_paranoia_check(struct mac_serial *info,
		      dev_t device, const char *routine)
{
#ifdef SERIAL_PARANOIA_CHECK
	static const char *badmagic =
		"Warning: bad magic number for serial struct (%d, %d) in %s\n";
	static const char *badinfo =
		"Warning: null mac_serial for (%d, %d) in %s\n";

	if (!info) {
		printk(badinfo, MAJOR(device), MINOR(device), routine);
		return 1;
	}
	if (info->magic != SERIAL_MAGIC) {
		printk(badmagic, MAJOR(device), MINOR(device), routine);
		return 1;
	}
#endif
	return 0;
}

/* 
 * Reading and writing Z8530 registers.
 */
static inline unsigned char __pmac read_zsreg(struct mac_zschannel *channel,
					      unsigned char reg)
{
	unsigned char retval;
	unsigned long flags;

	/*
	 * We have to make this atomic.
	 */
	spin_lock_irqsave(&channel->lock, flags);
	if (reg != 0) {
		*channel->control = reg;
		RECOVERY_DELAY;
	}
	retval = *channel->control;
	RECOVERY_DELAY;
	spin_unlock_irqrestore(&channel->lock, flags);
	return retval;
}

static inline void __pmac write_zsreg(struct mac_zschannel *channel,
				      unsigned char reg, unsigned char value)
{
	unsigned long flags;

	spin_lock_irqsave(&channel->lock, flags);
	if (reg != 0) {
		*channel->control = reg;
		RECOVERY_DELAY;
	}
	*channel->control = value;
	RECOVERY_DELAY;
	spin_unlock_irqrestore(&channel->lock, flags);
	return;
}

static inline unsigned char __pmac read_zsdata(struct mac_zschannel *channel)
{
	unsigned char retval;

	retval = *channel->data;
	RECOVERY_DELAY;
	return retval;
}

static inline void write_zsdata(struct mac_zschannel *channel,
				unsigned char value)
{
	*channel->data = value;
	RECOVERY_DELAY;
	return;
}

static inline void load_zsregs(struct mac_zschannel *channel,
			       unsigned char *regs)
{
	ZS_CLEARERR(channel);
	ZS_CLEARFIFO(channel);
	/* Load 'em up */
	write_zsreg(channel, R4, regs[R4]);
	write_zsreg(channel, R10, regs[R10]);
	write_zsreg(channel, R3, regs[R3] & ~RxENABLE);
	write_zsreg(channel, R5, regs[R5] & ~TxENAB);
	write_zsreg(channel, R1, regs[R1]);
	write_zsreg(channel, R9, regs[R9]);
	write_zsreg(channel, R11, regs[R11]);
	write_zsreg(channel, R12, regs[R12]);
	write_zsreg(channel, R13, regs[R13]);
	write_zsreg(channel, R14, regs[R14]);
	write_zsreg(channel, R15, regs[R15]);
	write_zsreg(channel, R3, regs[R3]);
	write_zsreg(channel, R5, regs[R5]);
	return;
}

/* Sets or clears DTR/RTS on the requested line */
static inline void zs_rtsdtr(struct mac_serial *ss, int set)
{
	if (set)
		ss->curregs[5] |= (RTS | DTR);
	else
		ss->curregs[5] &= ~(RTS | DTR);
	write_zsreg(ss->zs_channel, 5, ss->curregs[5]);
	return;
}

/* Utility routines for the Zilog */
static inline int get_zsbaud(struct mac_serial *ss)
{
	struct mac_zschannel *channel = ss->zs_channel;
	int brg;

	if ((ss->curregs[R11] & TCBR) == 0) {
		/* higher rates don't use the baud rate generator */
		return (ss->curregs[R4] & X32CLK)? ZS_CLOCK/32: ZS_CLOCK/16;
	}
	/* The baud rate is split up between two 8-bit registers in
	 * what is termed 'BRG time constant' format in my docs for
	 * the chip, it is a function of the clk rate the chip is
	 * receiving which happens to be constant.
	 */
	brg = (read_zsreg(channel, 13) << 8);
	brg |= read_zsreg(channel, 12);
	return BRG_TO_BPS(brg, (ZS_CLOCK/(ss->clk_divisor)));
}

/* On receive, this clears errors and the receiver interrupts */
static inline void rs_recv_clear(struct mac_zschannel *zsc)
{
	write_zsreg(zsc, 0, ERR_RES);
	write_zsreg(zsc, 0, RES_H_IUS); /* XXX this is unnecessary */
}

/*
 * Reset a Descriptor-Based DMA channel.
 */
static void dbdma_reset(volatile struct dbdma_regs *dma)
{
	int i;

	out_le32(&dma->control, (WAKE|FLUSH|PAUSE|RUN) << 16);

	/*
	 * Yes this looks peculiar, but apparently it needs to be this
	 * way on some machines.  (We need to make sure the DBDMA
	 * engine has actually got the write above and responded
	 * to it. - paulus)
	 */
	for (i = 200; i > 0; --i)
		if (ld_le32(&dma->status) & RUN)
			udelay(1);
}

/*
 * Tells a DBDMA channel to stop and write any buffered data
 * it might have to memory.
 */
static _INLINE_ void dbdma_flush(volatile struct dbdma_regs *dma)
{
	int i = 0;

	out_le32(&dma->control, (FLUSH << 16) | FLUSH);
	while (((in_le32(&dma->status) & FLUSH) != 0) && (i++ < 100))
		udelay(1);
}

/*
 * ----------------------------------------------------------------------
 *
 * Here starts the interrupt handling routines.  All of the following
 * subroutines are declared as inline and are folded into
 * rs_interrupt().  They were separated out for readability's sake.
 *
 * 				- Ted Ts'o ([e-mail]), 7-Mar-93
 * -----------------------------------------------------------------------
 */

/*
 * This routine is used by the interrupt handler to schedule
 * processing in the software interrupt portion of the driver.
 */
static _INLINE_ void rs_sched_event(struct mac_serial *info,
				  int event)
{
	info->event |= 1 << event;
	queue_task(&info->tqueue, &tq_serial);
	mark_bh(MACSERIAL_BH);
}

/* Work out the flag value for a z8530 status value. */
static _INLINE_ int stat_to_flag(int stat)
{
	int flag;

	if (stat & Rx_OVR) {
		flag = TTY_OVERRUN;
	} else if (stat & FRM_ERR) {
		flag = TTY_FRAME;
	} else if (stat & PAR_ERR) {
		flag = TTY_PARITY;
	} else
		flag = 0;
	return flag;
}

static _INLINE_ void receive_chars(struct mac_serial *info,
				   struct pt_regs *regs)
{
	struct tty_struct *tty = info->tty;
	unsigned char ch, stat, flag;

	while ((read_zsreg(info->zs_channel, 0) & Rx_CH_AV) != 0) {

		stat = read_zsreg(info->zs_channel, R1);
		ch = read_zsdata(info->zs_channel);

#ifdef CONFIG_KGDB
		if (info->kgdb_channel) {
			if (ch == 0x03 || ch == '$')
				breakpoint();
			if (stat & (Rx_OVR|FRM_ERR|PAR_ERR))
				write_zsreg(info->zs_channel, 0, ERR_RES);
			return;
		}
#endif
		if (!tty)
			continue;
		if (tty->flip.count >= TTY_FLIPBUF_SIZE)
			tty_flip_buffer_push(tty);

		if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
			static int flip_buf_ovf;
			if (++flip_buf_ovf <= 1)
				printk("FB. overflow: %d\n", flip_buf_ovf);
			break;
		}
		tty->flip.count++;
		{
			static int flip_max_cnt;
			if (flip_max_cnt < tty->flip.count)
				flip_max_cnt = tty->flip.count;
		}
		flag = stat_to_flag(stat);
		if (flag)
			/* reset the error indication */
			write_zsreg(info->zs_channel, 0, ERR_RES);
		*tty->flip.flag_buf_ptr++ = flag;
		*tty->flip.char_buf_ptr++ = ch;
	}
	if (tty)
		tty_flip_buffer_push(tty);
}

static void transmit_chars(struct mac_serial *info)
{
	unsigned long flags;

	save_flags(flags);
	cli();
	if ((read_zsreg(info->zs_channel, 0) & Tx_BUF_EMP) == 0)
		goto out;
	info->tx_active = 0;

	if (info->x_char) {
		/* Send next char */
		write_zsdata(info->zs_channel, info->x_char);
		info->x_char = 0;
		info->tx_active = 1;
		goto out;
	}

	if ((info->xmit_cnt <= 0) || info->tty->stopped || info->tx_stopped) {
		write_zsreg(info->zs_channel, 0, RES_Tx_P);
		goto out;
	}

	/* Send char */
	write_zsdata(info->zs_channel, info->xmit_buf[info->xmit_tail++]);
	info->xmit_tail = info->xmit_tail & (SERIAL_XMIT_SIZE-1);
	info->xmit_cnt--;
	info->tx_active = 1;

	if (info->xmit_cnt < WAKEUP_CHARS)
		rs_sched_event(info, RS_EVENT_WRITE_WAKEUP);

 out:
	restore_flags(flags);
}

static _INLINE_ void status_handle(struct mac_serial *info)
{
	unsigned char status;

	/* Get status from Read Register 0 */
	status = read_zsreg(info->zs_channel, 0);

	/* Check for DCD transitions */
	if (((status ^ info->read_reg_zero) & DCD) != 0
	    && info->tty && !C_CLOCAL(info->tty)) {
		if (status & DCD) {
			wake_up_interruptible(&info->open_wait);
		} else if (!(info->flags & ZILOG_CALLOUT_ACTIVE)) {
			if (info->tty)
				tty_hangup(info->tty);
		}
	}

	/* Check for CTS transitions */