hvsi.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 1,320 行 · 第 1/3 页

/*
 * Copyright (C) 2004 Hollis Blanchard <[e-mail]>, IBM
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

/* Host Virtual Serial Interface (HVSI) is a protocol between the hosted OS
 * and the service processor on IBM pSeries servers. On these servers, there
 * are no serial ports under the OS's control, and sometimes there is no other
 * console available either. However, the service processor has two standard
 * serial ports, so this over-complicated protocol allows the OS to control
 * those ports by proxy.
 *
 * Besides data, the procotol supports the reading/writing of the serial
 * port's DTR line, and the reading of the CD line. This is to allow the OS to
 * control a modem attached to the service processor's serial port. Note that
 * the OS cannot change the speed of the port through this protocol.
 */

/* TODO:
 * test FSP reset
 * add udbg support for xmon/kdb
 */

#undef DEBUG

#include <linux/console.h>
#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/major.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/sysrq.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <asm/hvcall.h>
#include <asm/hvconsole.h>
#include <asm/prom.h>
#include <asm/uaccess.h>
#include <asm/vio.h>

#define HVSI_MAJOR	229
#define HVSI_MINOR	128
#define MAX_NR_HVSI_CONSOLES 4

#define HVSI_TIMEOUT (5*HZ)
#define HVSI_VERSION 1
#define HVSI_MAX_PACKET 256
#define HVSI_MAX_READ 16
#define HVSI_MAX_OUTGOING_DATA 12
#define N_OUTBUF 12

/*
 * we pass data via two 8-byte registers, so we would like our char arrays
 * properly aligned for those loads.
 */
#define __ALIGNED__	__attribute__((__aligned__(sizeof(long))))

struct hvsi_struct {
	struct work_struct writer;
	wait_queue_head_t emptyq; /* woken when outbuf is emptied */
	wait_queue_head_t stateq; /* woken when HVSI state changes */
	spinlock_t lock;
	int index;
	struct tty_struct *tty;
	unsigned int count;
	uint8_t throttle_buf[128];
	uint8_t outbuf[N_OUTBUF]; /* to implement write_room and chars_in_buffer */
	/* inbuf is for packet reassembly. leave a little room for leftovers. */
	uint8_t inbuf[HVSI_MAX_PACKET + HVSI_MAX_READ];
	uint8_t *inbuf_end;
	int n_throttle;
	int n_outbuf;
	uint32_t vtermno;
	uint32_t virq;
	atomic_t seqno; /* HVSI packet sequence number */
	uint16_t mctrl;
	uint8_t state;  /* HVSI protocol state */
	uint8_t flags;
#ifdef CONFIG_MAGIC_SYSRQ
	uint8_t sysrq;
#endif /* CONFIG_MAGIC_SYSRQ */
};
static struct hvsi_struct hvsi_ports[MAX_NR_HVSI_CONSOLES];

static struct tty_driver *hvsi_driver;
static int hvsi_count;
static int (*hvsi_wait)(struct hvsi_struct *hp, int state);

enum HVSI_PROTOCOL_STATE {
	HVSI_CLOSED,
	HVSI_WAIT_FOR_VER_RESPONSE,
	HVSI_WAIT_FOR_VER_QUERY,
	HVSI_OPEN,
	HVSI_WAIT_FOR_MCTRL_RESPONSE,
};
#define HVSI_CONSOLE 0x1

#define VS_DATA_PACKET_HEADER           0xff
#define VS_CONTROL_PACKET_HEADER        0xfe
#define VS_QUERY_PACKET_HEADER          0xfd
#define VS_QUERY_RESPONSE_PACKET_HEADER 0xfc

/* control verbs */
#define VSV_SET_MODEM_CTL    1 /* to service processor only */
#define VSV_MODEM_CTL_UPDATE 2 /* from service processor only */
#define VSV_CLOSE_PROTOCOL   3

/* query verbs */
#define VSV_SEND_VERSION_NUMBER 1
#define VSV_SEND_MODEM_CTL_STATUS 2

/* yes, these masks are not consecutive. */
#define HVSI_TSDTR 0x01
#define HVSI_TSCD  0x20

struct hvsi_header {
	uint8_t  type;
	uint8_t  len;
	uint16_t seqno;
} __attribute__((packed));

struct hvsi_data {
	uint8_t  type;
	uint8_t  len;
	uint16_t seqno;
	uint8_t  data[HVSI_MAX_OUTGOING_DATA];
} __attribute__((packed));

struct hvsi_control {
	uint8_t  type;
	uint8_t  len;
	uint16_t seqno;
	uint16_t verb;
	/* optional depending on verb: */
	uint32_t word;
	uint32_t mask;
} __attribute__((packed));

struct hvsi_query {
	uint8_t  type;
	uint8_t  len;
	uint16_t seqno;
	uint16_t verb;
} __attribute__((packed));

struct hvsi_query_response {
	uint8_t  type;
	uint8_t  len;
	uint16_t seqno;
	uint16_t verb;
	uint16_t query_seqno;
	union {
		uint8_t  version;
		uint32_t mctrl_word;
	} u;
} __attribute__((packed));

static inline int is_open(struct hvsi_struct *hp)
{
	/* if we're waiting for an mctrl then we're already open */
	return (hp->state == HVSI_OPEN)
			|| (hp->state == HVSI_WAIT_FOR_MCTRL_RESPONSE);
}

static inline void print_state(struct hvsi_struct *hp)
{
#ifdef DEBUG
	static const char *state_names[] = {
		"HVSI_CLOSED",
		"HVSI_WAIT_FOR_VER_RESPONSE",
		"HVSI_WAIT_FOR_VER_QUERY",
		"HVSI_OPEN",
		"HVSI_WAIT_FOR_MCTRL_RESPONSE",
	};
	const char *name = state_names[hp->state];

	if (hp->state > (sizeof(state_names)/sizeof(char*)))
		name = "UNKNOWN";

	pr_debug("hvsi%i: state = %s\n", hp->index, name);
#endif /* DEBUG */
}

static inline void __set_state(struct hvsi_struct *hp, int state)
{
	hp->state = state;
	print_state(hp);
	wake_up_all(&hp->stateq);
}

static inline void set_state(struct hvsi_struct *hp, int state)
{
	unsigned long flags;

	spin_lock_irqsave(&hp->lock, flags);
	__set_state(hp, state);
	spin_unlock_irqrestore(&hp->lock, flags);
}

static inline int len_packet(const uint8_t *packet)
{
	return (int)((struct hvsi_header *)packet)->len;
}

static inline int is_header(const uint8_t *packet)
{
	struct hvsi_header *header = (struct hvsi_header *)packet;
	return header->type >= VS_QUERY_RESPONSE_PACKET_HEADER;
}

static inline int got_packet(const struct hvsi_struct *hp, uint8_t *packet)
{
	if (hp->inbuf_end < packet + sizeof(struct hvsi_header))
		return 0; /* don't even have the packet header */

	if (hp->inbuf_end < (packet + len_packet(packet)))
		return 0; /* don't have the rest of the packet */

	return 1;
}

/* shift remaining bytes in packetbuf down */
static void compact_inbuf(struct hvsi_struct *hp, uint8_t *read_to)
{
	int remaining = (int)(hp->inbuf_end - read_to);

	pr_debug("%s: %i chars remain\n", __FUNCTION__, remaining);

	if (read_to != hp->inbuf)
		memmove(hp->inbuf, read_to, remaining);

	hp->inbuf_end = hp->inbuf + remaining;
}

#ifdef DEBUG
#define dbg_dump_packet(packet) dump_packet(packet)
#define dbg_dump_hex(data, len) dump_hex(data, len)
#else
#define dbg_dump_packet(packet) do { } while (0)
#define dbg_dump_hex(data, len) do { } while (0)
#endif

static void dump_hex(const uint8_t *data, int len)
{
	int i;

	printk("    ");
	for (i=0; i < len; i++)
		printk("%.2x", data[i]);

	printk("\n    ");
	for (i=0; i < len; i++) {
		if (isprint(data[i]))
			printk("%c", data[i]);
		else
			printk(".");
	}
	printk("\n");
}

static void dump_packet(uint8_t *packet)
{
	struct hvsi_header *header = (struct hvsi_header *)packet;

	printk("type 0x%x, len %i, seqno %i:\n", header->type, header->len,
			header->seqno);

	dump_hex(packet, header->len);
}

/* can't use hvc_get_chars because that strips CRs */
static int hvsi_read(struct hvsi_struct *hp, char *buf, int count)
{
	unsigned long got;

	if (plpar_hcall(H_GET_TERM_CHAR, hp->vtermno, 0, 0, 0, &got,
			(unsigned long *)buf, (unsigned long *)buf+1) == H_Success)
		return got;
	return 0;
}

/*
 * we can't call tty_hangup() directly here because we need to call that
 * outside of our lock
 */
static struct tty_struct *hvsi_recv_control(struct hvsi_struct *hp,
		uint8_t *packet)
{
	struct tty_struct *to_hangup = NULL;
	struct hvsi_control *header = (struct hvsi_control *)packet;

	switch (header->verb) {
		case VSV_MODEM_CTL_UPDATE:
			if ((header->word & HVSI_TSCD) == 0) {
				/* CD went away; no more connection */
				pr_debug("hvsi%i: CD dropped\n", hp->index);
				hp->mctrl &= TIOCM_CD;
				if (!(hp->tty->flags & CLOCAL))
					to_hangup = hp->tty;
			}
			break;
		case VSV_CLOSE_PROTOCOL:
			printk(KERN_DEBUG
				"hvsi%i: service processor closed connection!\n", hp->index);
			__set_state(hp, HVSI_CLOSED);
			to_hangup = hp->tty;
			hp->tty = NULL;
			break;
		default:
			printk(KERN_WARNING "hvsi%i: unknown HVSI control packet: ",
				hp->index);
			dump_packet(packet);
			break;
	}

	return to_hangup;
}

static void hvsi_recv_response(struct hvsi_struct *hp, uint8_t *packet)
{
	struct hvsi_query_response *resp = (struct hvsi_query_response *)packet;

	switch (hp->state) {
		case HVSI_WAIT_FOR_VER_RESPONSE:
			__set_state(hp, HVSI_WAIT_FOR_VER_QUERY);
			break;
		case HVSI_WAIT_FOR_MCTRL_RESPONSE:
			hp->mctrl = 0;
			if (resp->u.mctrl_word & HVSI_TSDTR)
				hp->mctrl |= TIOCM_DTR;
			if (resp->u.mctrl_word & HVSI_TSCD)
				hp->mctrl |= TIOCM_CD;
			__set_state(hp, HVSI_OPEN);
			break;
		default:
			printk(KERN_ERR "hvsi%i: unexpected query response: ", hp->index);
			dump_packet(packet);
			break;
	}
}

/* respond to service processor's version query */
static int hvsi_version_respond(struct hvsi_struct *hp, uint16_t query_seqno)
{
	struct hvsi_query_response packet __ALIGNED__;
	int wrote;

	packet.type = VS_QUERY_RESPONSE_PACKET_HEADER;
	packet.len = sizeof(struct hvsi_query_response);
	packet.seqno = atomic_inc_return(&hp->seqno);
	packet.verb = VSV_SEND_VERSION_NUMBER;
	packet.u.version = HVSI_VERSION;
	packet.query_seqno = query_seqno+1;

	pr_debug("%s: sending %i bytes\n", __FUNCTION__, packet.len);
	dbg_dump_hex((uint8_t*)&packet, packet.len);

	wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.len);
	if (wrote != packet.len) {
		printk(KERN_ERR "hvsi%i: couldn't send query response!\n",
			hp->index);
		return -EIO;
	}

	return 0;
}

static void hvsi_recv_query(struct hvsi_struct *hp, uint8_t *packet)
{
	struct hvsi_query *query = (struct hvsi_query *)packet;

	switch (hp->state) {
		case HVSI_WAIT_FOR_VER_QUERY:
			__set_state(hp, HVSI_OPEN);
			hvsi_version_respond(hp, query->seqno);
			break;
		default:
			printk(KERN_ERR "hvsi%i: unexpected query: ", hp->index);
			dump_packet(packet);
			break;
	}
}

static void hvsi_insert_chars(struct hvsi_struct *hp, const char *buf, int len)
{
	int i;

	for (i=0; i < len; i++) {
		char c = buf[i];
#ifdef CONFIG_MAGIC_SYSRQ
		if (c == '\0') {
			hp->sysrq = 1;
			continue;
		} else if (hp->sysrq) {
			handle_sysrq(c, NULL, hp->tty);
			hp->sysrq = 0;
			continue;
		}
#endif /* CONFIG_MAGIC_SYSRQ */
		tty_insert_flip_char(hp->tty, c, 0);
	}
}

/*
 * We could get 252 bytes of data at once here. But the tty layer only
 * throttles us at TTY_THRESHOLD_THROTTLE (128) bytes, so we could overflow
 * it. Accordingly we won't send more than 128 bytes at a time to the flip
 * buffer, which will give the tty buffer a chance to throttle us. Should the
 * value of TTY_THRESHOLD_THROTTLE change in n_tty.c, this code should be
 * revisited.
 */
#define TTY_THRESHOLD_THROTTLE 128
static struct tty_struct *hvsi_recv_data(struct hvsi_struct *hp,
		const uint8_t *packet)
{
	const struct hvsi_header *header = (const struct hvsi_header *)packet;
	const uint8_t *data = packet + sizeof(struct hvsi_header);
	int datalen = header->len - sizeof(struct hvsi_header);
	int overflow = datalen - TTY_THRESHOLD_THROTTLE;

	pr_debug("queueing %i chars '%.*s'\n", datalen, datalen, data);

	if (datalen == 0)