1 files changed, 1314 insertions, 0 deletions

diff --git a/drivers/tty/hvc/hvsi.c b/drivers/tty/hvc/hvsi.c
new file mode 100644
index 000000000000..67a75a502c01
--- /dev/null
+++ b/drivers/tty/hvc/hvsi.c
@@ -0,0 +1,1314 @@
+/*
+ * Copyright (C) 2004 Hollis Blanchard <hollisb@us.ibm.com>, 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.
+ */
+
+#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/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>
+#include <asm/param.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 delayed_work writer;
+        struct work_struct handshaker;
+        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;
+        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,
+        HVSI_FSP_DIED,
+};
+#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_console(struct hvsi_struct *hp)
+{
+        return hp->flags & HVSI_CONSOLE;
+}
+
+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",
+                "HVSI_FSP_DIED",
+        };
+        const char *name = (hp->state < ARRAY_SIZE(state_names))
+                ? state_names[hp->state] : "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", __func__, 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);
+}
+
+static int hvsi_read(struct hvsi_struct *hp, char *buf, int count)
+{
+        unsigned long got;
+
+        got = hvc_get_chars(hp->vtermno, buf, count);
+
+        return got;
+}
+
+static void hvsi_recv_control(struct hvsi_struct *hp, uint8_t *packet,
+        struct tty_struct **to_hangup, struct hvsi_struct **to_handshake)
+{
+        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 userland hasn't done an open(2) yet, hp->tty is NULL. */
+                                if (hp->tty && !(hp->tty->flags & CLOCAL))
+                                        *to_hangup = hp->tty;
+                        }
+                        break;
+                case VSV_CLOSE_PROTOCOL:
+                        pr_debug("hvsi%i: service processor came back\n", hp->index);
+                        if (hp->state != HVSI_CLOSED) {
+                                *to_handshake = hp;
+                        }
+                        break;
+                default:
+                        printk(KERN_WARNING "hvsi%i: unknown HVSI control packet: ",
+                                hp->index);
+                        dump_packet(packet);
+                        break;
+        }
+}
+
+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", __func__, 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:
+                        hvsi_version_respond(hp, query->seqno);
+                        __set_state(hp, HVSI_OPEN);
+                        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);
+                        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)
+                return NULL;
+
+        if (overflow > 0) {
+                pr_debug("%s: got >TTY_THRESHOLD_THROTTLE bytes\n", __func__);
+                datalen = TTY_THRESHOLD_THROTTLE;
+        }
+
+        hvsi_insert_chars(hp, data, datalen);
+
+        if (overflow > 0) {
+                /*
+                 * we still have more data to deliver, so we need to save off the
+                 * overflow and send it later
+                 */
+                pr_debug("%s: deferring overflow\n", __func__);
+                memcpy(hp->throttle_buf, data + TTY_THRESHOLD_THROTTLE, overflow);
+                hp->n_throttle = overflow;
+        }
+
+        return hp->tty;
+}
+
+/*
+ * Returns true/false indicating data successfully read from hypervisor.
+ * Used both to get packets for tty connections and to advance the state
+ * machine during console handshaking (in which case tty = NULL and we ignore
+ * incoming data).
+ */
+static int hvsi_load_chunk(struct hvsi_struct *hp, struct tty_struct **flip,
+                struct tty_struct **hangup, struct hvsi_struct **handshake)
+{
+        uint8_t *packet = hp->inbuf;
+        int chunklen;
+
+        *flip = NULL;
+        *hangup = NULL;
+        *handshake = NULL;
+
+        chunklen = hvsi_read(hp, hp->inbuf_end, HVSI_MAX_READ);
+        if (chunklen == 0) {
+                pr_debug("%s: 0-length read\n", __func__);
+                return 0;
+        }
+
+        pr_debug("%s: got %i bytes\n", __func__, chunklen);
+        dbg_dump_hex(hp->inbuf_end, chunklen);
+
+        hp->inbuf_end += chunklen;
+
+        /* handle all completed packets */
+        while ((packet < hp->inbuf_end) && got_packet(hp, packet)) {
+                struct hvsi_header *header = (struct hvsi_header *)packet;
+
+                if (!is_header(packet)) {
+                        printk(KERN_ERR "hvsi%i: got malformed packet\n", hp->index);
+                        /* skip bytes until we find a header or run out of data */
+                        while ((packet < hp->inbuf_end) && (!is_header(packet)))
+                                packet++;
+                        continue;
+                }
+
+                pr_debug("%s: handling %i-byte packet\n", __func__,
+                                len_packet(packet));
+                dbg_dump_packet(packet);
+
+                switch (header->type) {
+                        case VS_DATA_PACKET_HEADER:
+                                if (!is_open(hp))
+                                        break;
+                                if (hp->tty == NULL)
+                                        break; /* no tty buffer to put data in */
+                                *flip = hvsi_recv_data(hp, packet);
+                                break;
+                        case VS_CONTROL_PACKET_HEADER:
+                                hvsi_recv_control(hp, packet, hangup, handshake);
+                                break;
+                        case VS_QUERY_RESPONSE_PACKET_HEADER:
+                                hvsi_recv_response(hp, packet);
+                                break;
+                        case VS_QUERY_PACKET_HEADER:
+                                hvsi_recv_query(hp, packet);
+                                break;
+                        default:
+                                printk(KERN_ERR "hvsi%i: unknown HVSI packet type 0x%x\n",
+                                                hp->index, header->type);
+                                dump_packet(packet);
+                                break;
+                }
+
+                packet += len_packet(packet);
+
+                if (*hangup || *handshake) {
+                        pr_debug("%s: hangup or handshake\n", __func__);
+                        /*
+                         * we need to send the hangup now before receiving any more data.
+                         * If we get "data, hangup, data", we can't deliver the second
+                         * data before the hangup.
+                         */
+                        break;
+                }
+        }
+
+        compact_inbuf(hp, packet);
+
+        return 1;
+}
+
+static void hvsi_send_overflow(struct hvsi_struct *hp)
+{
+        pr_debug("%s: delivering %i bytes overflow\n", __func__,
+                        hp->n_throttle);
+
+        hvsi_insert_chars(hp, hp->throttle_buf, hp->n_throttle);
+        hp->n_throttle = 0;
+}
+
+/*
+ * must get all pending data because we only get an irq on empty->non-empty
+ * transition
+ */
+static irqreturn_t hvsi_interrupt(int irq, void *arg)
+{
+        struct hvsi_struct *hp = (struct hvsi_struct *)arg;
+        struct tty_struct *flip;
+        struct tty_struct *hangup;
+        struct hvsi_struct *handshake;
+        unsigned long flags;
+        int again = 1;
+
+        pr_debug("%s\n", __func__);
+
+        while (again) {
+                spin_lock_irqsave(&hp->lock, flags);
+                again = hvsi_load_chunk(hp, &flip, &hangup, &handshake);
+                spin_unlock_irqrestore(&hp->lock, flags);
+
+                /*
+                 * we have to call tty_flip_buffer_push() and tty_hangup() outside our
+                 * spinlock. But we also have to keep going until we've read all the
+                 * available data.
+                 */
+
+                if (flip) {
+                        /* there was data put in the tty flip buffer */
+                        tty_flip_buffer_push(flip);
+                        flip = NULL;
+                }
+
+                if (hangup) {
+                        tty_hangup(hangup);
+                }
+
+                if (handshake) {
+                        pr_debug("hvsi%i: attempting re-handshake\n", handshake->index);
+                        schedule_work(&handshake->handshaker);
+                }
+        }
+
+        spin_lock_irqsave(&hp->lock, flags);
+        if (hp->tty && hp->n_throttle
+                        && (!test_bit(TTY_THROTTLED, &hp->tty->flags))) {
+                /* we weren't hung up and we weren't throttled, so we can deliver the
+                 * rest now */
+                flip = hp->tty;
+                hvsi_send_overflow(hp);
+        }
+        spin_unlock_irqrestore(&hp->lock, flags);
+
+        if (flip) {
+                tty_flip_buffer_push(flip);
+        }
+
+        return IRQ_HANDLED;
+}
+
+/* for boot console, before the irq handler is running */
+static int __init poll_for_state(struct hvsi_struct *hp, int state)
+{
+        unsigned long end_jiffies = jiffies + HVSI_TIMEOUT;
+
+        for (;;) {
+                hvsi_interrupt(hp->virq, (void *)hp); /* get pending data */
+
+                if (hp->state == state)
+                        return 0;
+
+                mdelay(5);
+                if (time_after(jiffies, end_jiffies))
+                        return -EIO;
+        }
+}
+
+/* wait for irq handler to change our state */
+static int wait_for_state(struct hvsi_struct *hp, int state)
+{
+        int ret = 0;
+
+        if (!wait_event_timeout(hp->stateq, (hp->state == state), HVSI_TIMEOUT))
+                ret = -EIO;
+
+        return ret;
+}
+
+static int hvsi_query(struct hvsi_struct *hp, uint16_t verb)
+{
+        struct hvsi_query packet __ALIGNED__;
+        int wrote;
+
+        packet.type = VS_QUERY_PACKET_HEADER;
+        packet.len = sizeof(struct hvsi_query);
+        packet.seqno = atomic_inc_return(&hp->seqno);
+        packet.verb = verb;
+
+        pr_debug("%s: sending %i bytes\n", __func__, 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 (%i)!\n", hp->index,
+                        wrote);
+                return -EIO;
+        }
+
+        return 0;
+}
+
+static int hvsi_get_mctrl(struct hvsi_struct *hp)
+{
+        int ret;
+
+        set_state(hp, HVSI_WAIT_FOR_MCTRL_RESPONSE);
+        hvsi_query(hp, VSV_SEND_MODEM_CTL_STATUS);
+
+        ret = hvsi_wait(hp, HVSI_OPEN);
+        if (ret < 0) {
+                printk(KERN_ERR "hvsi%i: didn't get modem flags\n", hp->index);
+                set_state(hp, HVSI_OPEN);
+                return ret;
+        }
+
+        pr_debug("%s: mctrl 0x%x\n", __func__, hp->mctrl);
+
+        return 0;
+}
+
+/* note that we can only set DTR */
+static int hvsi_set_mctrl(struct hvsi_struct *hp, uint16_t mctrl)
+{
+        struct hvsi_control packet __ALIGNED__;
+        int wrote;
+
+        packet.type = VS_CONTROL_PACKET_HEADER,
+        packet.seqno = atomic_inc_return(&hp->seqno);
+        packet.len = sizeof(struct hvsi_control);
+        packet.verb = VSV_SET_MODEM_CTL;
+        packet.mask = HVSI_TSDTR;
+
+        if (mctrl & TIOCM_DTR)
+                packet.word = HVSI_TSDTR;
+
+        pr_debug("%s: sending %i bytes\n", __func__, 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 set DTR!\n", hp->index);
+                return -EIO;
+        }
+
+        return 0;
+}
+
+static void hvsi_drain_input(struct hvsi_struct *hp)
+{
+        uint8_t buf[HVSI_MAX_READ] __ALIGNED__;
+        unsigned long end_jiffies = jiffies + HVSI_TIMEOUT;
+
+        while (time_before(end_jiffies, jiffies))
+                if (0 == hvsi_read(hp, buf, HVSI_MAX_READ))
+                        break;
+}
+
+static int hvsi_handshake(struct hvsi_struct *hp)
+{
+        int ret;
+
+        /*
+         * We could have a CLOSE or other data waiting for us before we even try
+         * to open; try to throw it all away so we don't get confused. (CLOSE
+         * is the first message sent up the pipe when the FSP comes online. We
+         * need to distinguish between "it came up a while ago and we're the first
+         * user" and "it was just reset before it saw our handshake packet".)
+         */
+        hvsi_drain_input(hp);
+
+        set_state(hp, HVSI_WAIT_FOR_VER_RESPONSE);
+        ret = hvsi_query(hp, VSV_SEND_VERSION_NUMBER);
+        if (ret < 0) {
+                printk(KERN_ERR "hvsi%i: couldn't send version query\n", hp->index);
+                return ret;
+        }
+
+        ret = hvsi_wait(hp, HVSI_OPEN);
+        if (ret < 0)
+                return ret;
+
+        return 0;
+}
+
+static void hvsi_handshaker(struct work_struct *work)
+{
+        struct hvsi_struct *hp =
+                container_of(work, struct hvsi_struct, handshaker);
+
+        if (hvsi_handshake(hp) >= 0)
+                return;
+
+        printk(KERN_ERR "hvsi%i: re-handshaking failed\n", hp->index);
+        if (is_console(hp)) {
+                /*
+                 * ttys will re-attempt the handshake via hvsi_open, but
+                 * the console will not.
+                 */
+                printk(KERN_ERR "hvsi%i: lost console!\n", hp->index);
+        }
+}
+
+static int hvsi_put_chars(struct hvsi_struct *hp, const char *buf, int count)
+{
+        struct hvsi_data packet __ALIGNED__;
+        int ret;
+
+        BUG_ON(count > HVSI_MAX_OUTGOING_DATA);
+
+        packet.type = VS_DATA_PACKET_HEADER;
+        packet.seqno = atomic_inc_return(&hp->seqno);
+        packet.len = count + sizeof(struct hvsi_header);
+        memcpy(&packet.data, buf, count);
+
+        ret = hvc_put_chars(hp->vtermno, (char *)&packet, packet.len);
+        if (ret == packet.len) {
+                /* return the number of chars written, not the packet length */
+                return count;
+        }
+        return ret; /* return any errors */
+}
+
+static void hvsi_close_protocol(struct hvsi_struct *hp)
+{
+        struct hvsi_control packet __ALIGNED__;
+
+        packet.type = VS_CONTROL_PACKET_HEADER;
+        packet.seqno = atomic_inc_return(&hp->seqno);
+        packet.len = 6;
+        packet.verb = VSV_CLOSE_PROTOCOL;
+
+        pr_debug("%s: sending %i bytes\n", __func__, packet.len);
+        dbg_dump_hex((uint8_t*)&packet, packet.len);
+
+        hvc_put_chars(hp->vtermno, (char *)&packet, packet.len);
+}
+
+static int hvsi_open(struct tty_struct *tty, struct file *filp)
+{
+        struct hvsi_struct *hp;
+        unsigned long flags;
+        int line = tty->index;
+        int ret;
+
+        pr_debug("%s\n", __func__);
+
+        if (line < 0 || line >= hvsi_count)
+                return -ENODEV;
+        hp = &hvsi_ports[line];
+
+        tty->driver_data = hp;
+
+        mb();
+        if (hp->state == HVSI_FSP_DIED)
+                return -EIO;
+
+        spin_lock_irqsave(&hp->lock, flags);
+        hp->tty = tty;
+        hp->count++;
+        atomic_set(&hp->seqno, 0);
+        h_vio_signal(hp->vtermno, VIO_IRQ_ENABLE);
+        spin_unlock_irqrestore(&hp->lock, flags);
+
+        if (is_console(hp))
+                return 0; /* this has already been handshaked as the console */
+
+        ret = hvsi_handshake(hp);
+        if (ret < 0) {
+                printk(KERN_ERR "%s: HVSI handshaking failed\n", tty->name);
+                return ret;
+        }
+
+        ret = hvsi_get_mctrl(hp);
+        if (ret < 0) {
+                printk(KERN_ERR "%s: couldn't get initial modem flags\n", tty->name);
+                return ret;
+        }
+
+        ret = hvsi_set_mctrl(hp, hp->mctrl | TIOCM_DTR);
+        if (ret < 0) {
+                printk(KERN_ERR "%s: couldn't set DTR\n", tty->name);
+                return ret;
+        }
+
+        return 0;
+}
+
+/* wait for hvsi_write_worker to empty hp->outbuf */
+static void hvsi_flush_output(struct hvsi_struct *hp)
+{
+        wait_event_timeout(hp->emptyq, (hp->n_outbuf <= 0), HVSI_TIMEOUT);
+
+        /* 'writer' could still be pending if it didn't see n_outbuf = 0 yet */
+        cancel_delayed_work_sync(&hp->writer);
+        flush_work_sync(&hp->handshaker);
+
+        /*
+         * it's also possible that our timeout expired and hvsi_write_worker
+         * didn't manage to push outbuf. poof.
+         */
+        hp->n_outbuf = 0;
+}
+
+static void hvsi_close(struct tty_struct *tty, struct file *filp)
+{
+        struct hvsi_struct *hp = tty->driver_data;
+        unsigned long flags;
+
+        pr_debug("%s\n", __func__);
+
+        if (tty_hung_up_p(filp))
+                return;
+
+        spin_lock_irqsave(&hp->lock, flags);
+
+        if (--hp->count == 0) {
+                hp->tty = NULL;
+                hp->inbuf_end = hp->inbuf; /* discard remaining partial packets */
+
+                /* only close down connection if it is not the console */
+                if (!is_console(hp)) {
+                        h_vio_signal(hp->vtermno, VIO_IRQ_DISABLE); /* no more irqs */
+                        __set_state(hp, HVSI_CLOSED);
+                        /*
+                         * any data delivered to the tty layer after this will be
+                         * discarded (except for XON/XOFF)
+                         */
+                        tty->closing = 1;
+
+                        spin_unlock_irqrestore(&hp->lock, flags);
+
+                        /* let any existing irq handlers finish. no more will start. */
+                        synchronize_irq(hp->virq);
+
+                        /* hvsi_write_worker will re-schedule until outbuf is empty. */
+                        hvsi_flush_output(hp);
+
+                        /* tell FSP to stop sending data */
+                        hvsi_close_protocol(hp);
+
+                        /*
+                         * drain anything FSP is still in the middle of sending, and let
+                         * hvsi_handshake drain the rest on the next open.
+                         */
+                        hvsi_drain_input(hp);
+
+                        spin_lock_irqsave(&hp->lock, flags);
+                }
+        } else if (hp->count < 0)
+                printk(KERN_ERR "hvsi_close %lu: oops, count is %d\n",
+                       hp - hvsi_ports, hp->count);
+
+        spin_unlock_irqrestore(&hp->lock, flags);
+}
+
+static void hvsi_hangup(struct tty_struct *tty)
+{
+        struct hvsi_struct *hp = tty->driver_data;
+        unsigned long flags;
+
+        pr_debug("%s\n", __func__);
+
+        spin_lock_irqsave(&hp->lock, flags);
+
+        hp->count = 0;
+        hp->n_outbuf = 0;
+        hp->tty = NULL;
+
+        spin_unlock_irqrestore(&hp->lock, flags);
+}
+
+/* called with hp->lock held */
+static void hvsi_push(struct hvsi_struct *hp)
+{
+        int n;
+
+        if (hp->n_outbuf <= 0)
+                return;
+
+        n = hvsi_put_chars(hp, hp->outbuf, hp->n_outbuf);
+        if (n > 0) {
+                /* success */
+                pr_debug("%s: wrote %i chars\n", __func__, n);
+                hp->n_outbuf = 0;
+        } else if (n == -EIO) {
+                __set_state(hp, HVSI_FSP_DIED);
+                printk(KERN_ERR "hvsi%i: service processor died\n", hp->index);
+        }
+}
+
+/* hvsi_write_worker will keep rescheduling itself until outbuf is empty */
+static void hvsi_write_worker(struct work_struct *work)
+{
+        struct hvsi_struct *hp =
+                container_of(work, struct hvsi_struct, writer.work);
+        unsigned long flags;
+#ifdef DEBUG
+        static long start_j = 0;
+
+        if (start_j == 0)
+                start_j = jiffies;
+#endif /* DEBUG */
+
+        spin_lock_irqsave(&hp->lock, flags);
+
+        pr_debug("%s: %i chars in buffer\n", __func__, hp->n_outbuf);
+
+        if (!is_open(hp)) {
+                /*
+                 * We could have a non-open connection if the service processor died
+                 * while we were busily scheduling ourselves. In that case, it could
+                 * be minutes before the service processor comes back, so only try
+                 * again once a second.
+                 */
+                schedule_delayed_work(&hp->writer, HZ);
+                goto out;
+        }
+
+        hvsi_push(hp);
+        if (hp->n_outbuf > 0)
+                schedule_delayed_work(&hp->writer, 10);
+        else {
+#ifdef DEBUG
+                pr_debug("%s: outbuf emptied after %li jiffies\n", __func__,
+                                jiffies - start_j);
+                start_j = 0;
+#endif /* DEBUG */
+                wake_up_all(&hp->emptyq);
+                tty_wakeup(hp->tty);
+        }
+
+out:
+        spin_unlock_irqrestore(&hp->lock, flags);
+}
+
+static int hvsi_write_room(struct tty_struct *tty)
+{
+        struct hvsi_struct *hp = tty->driver_data;
+
+        return N_OUTBUF - hp->n_outbuf;
+}
+
+static int hvsi_chars_in_buffer(struct tty_struct *tty)
+{
+        struct hvsi_struct *hp = tty->driver_data;
+
+        return hp->n_outbuf;
+}
+
+static int hvsi_write(struct tty_struct *tty,
+                     const unsigned char *buf, int count)
+{
+        struct hvsi_struct *hp = tty->driver_data;
+        const char *source = buf;
+        unsigned long flags;
+        int total = 0;
+        int origcount = count;
+
+        spin_lock_irqsave(&hp->lock, flags);
+
+        pr_debug("%s: %i chars in buffer\n", __func__, hp->n_outbuf);
+
+        if (!is_open(hp)) {
+                /* we're either closing or not yet open; don't accept data */
+                pr_debug("%s: not open\n", __func__);
+                goto out;
+        }
+
+        /*
+         * when the hypervisor buffer (16K) fills, data will stay in hp->outbuf
+         * and hvsi_write_worker will be scheduled. subsequent hvsi_write() calls
+         * will see there is no room in outbuf and return.
+         */
+        while ((count > 0) && (hvsi_write_room(hp->tty) > 0)) {
+                int chunksize = min(count, hvsi_write_room(hp->tty));
+
+                BUG_ON(hp->n_outbuf < 0);
+                memcpy(hp->outbuf + hp->n_outbuf, source, chunksize);
+                hp->n_outbuf += chunksize;
+
+                total += chunksize;
+                source += chunksize;
+                count -= chunksize;
+                hvsi_push(hp);
+        }
+
+        if (hp->n_outbuf > 0) {
+                /*
+                 * we weren't able to write it all to the hypervisor.
+                 * schedule another push attempt.
+                 */
+                schedule_delayed_work(&hp->writer, 10);
+        }
+
+out:
+        spin_unlock_irqrestore(&hp->lock, flags);
+
+        if (total != origcount)
+                pr_debug("%s: wanted %i, only wrote %i\n", __func__, origcount,
+                        total);
+
+        return total;
+}
+
+/*
+ * I have never seen throttle or unthrottle called, so this little throttle
+ * buffering scheme may or may not work.
+ */
+static void hvsi_throttle(struct tty_struct *tty)
+{
+        struct hvsi_struct *hp = tty->driver_data;
+
+        pr_debug("%s\n", __func__);
+
+        h_vio_signal(hp->vtermno, VIO_IRQ_DISABLE);
+}
+
+static void hvsi_unthrottle(struct tty_struct *tty)
+{
+        struct hvsi_struct *hp = tty->driver_data;
+        unsigned long flags;
+        int shouldflip = 0;
+
+        pr_debug("%s\n", __func__);
+
+        spin_lock_irqsave(&hp->lock, flags);
+        if (hp->n_throttle) {
+                hvsi_send_overflow(hp);
+                shouldflip = 1;
+        }
+        spin_unlock_irqrestore(&hp->lock, flags);
+
+        if (shouldflip)
+                tty_flip_buffer_push(hp->tty);
+
+        h_vio_signal(hp->vtermno, VIO_IRQ_ENABLE);
+}
+
+static int hvsi_tiocmget(struct tty_struct *tty, struct file *file)
+{
+        struct hvsi_struct *hp = tty->driver_data;
+
+        hvsi_get_mctrl(hp);
+        return hp->mctrl;
+}
+
+static int hvsi_tiocmset(struct tty_struct *tty, struct file *file,
+                unsigned int set, unsigned int clear)
+{
+        struct hvsi_struct *hp = tty->driver_data;
+        unsigned long flags;
+        uint16_t new_mctrl;
+
+        /* we can only alter DTR */
+        clear &= TIOCM_DTR;
+        set &= TIOCM_DTR;
+
+        spin_lock_irqsave(&hp->lock, flags);
+
+        new_mctrl = (hp->mctrl & ~clear) | set;
+
+        if (hp->mctrl != new_mctrl) {
+                hvsi_set_mctrl(hp, new_mctrl);
+                hp->mctrl = new_mctrl;
+        }
+        spin_unlock_irqrestore(&hp->lock, flags);
+
+        return 0;
+}
+
+
+static const struct tty_operations hvsi_ops = {
+        .open = hvsi_open,
+        .close = hvsi_close,
+        .write = hvsi_write,
+        .hangup = hvsi_hangup,
+        .write_room = hvsi_write_room,
+        .chars_in_buffer = hvsi_chars_in_buffer,
+        .throttle = hvsi_throttle,
+        .unthrottle = hvsi_unthrottle,
+        .tiocmget = hvsi_tiocmget,
+        .tiocmset = hvsi_tiocmset,
+};
+
+static int __init hvsi_init(void)
+{
+        int i;
+
+        hvsi_driver = alloc_tty_driver(hvsi_count);
+        if (!hvsi_driver)
+                return -ENOMEM;
+
+        hvsi_driver->owner = THIS_MODULE;
+        hvsi_driver->driver_name = "hvsi";
+        hvsi_driver->name = "hvsi";
+        hvsi_driver->major = HVSI_MAJOR;
+        hvsi_driver->minor_start = HVSI_MINOR;
+        hvsi_driver->type = TTY_DRIVER_TYPE_SYSTEM;
+        hvsi_driver->init_termios = tty_std_termios;
+        hvsi_driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL;
+        hvsi_driver->init_termios.c_ispeed = 9600;
+        hvsi_driver->init_termios.c_ospeed = 9600;
+        hvsi_driver->flags = TTY_DRIVER_REAL_RAW;
+        tty_set_operations(hvsi_driver, &hvsi_ops);
+
+        for (i=0; i < hvsi_count; i++) {
+                struct hvsi_struct *hp = &hvsi_ports[i];
+                int ret = 1;
+
+                ret = request_irq(hp->virq, hvsi_interrupt, IRQF_DISABLED, "hvsi", hp);
+                if (ret)
+                        printk(KERN_ERR "HVSI: couldn't reserve irq 0x%x (error %i)\n",
+                                hp->virq, ret);
+        }
+        hvsi_wait = wait_for_state; /* irqs active now */
+
+        if (tty_register_driver(hvsi_driver))
+                panic("Couldn't register hvsi console driver\n");
+
+        printk(KERN_DEBUG "HVSI: registered %i devices\n", hvsi_count);
+
+        return 0;
+}
+device_initcall(hvsi_init);
+
+/***** console (not tty) code: *****/
+
+static void hvsi_console_print(struct console *console, const char *buf,
+                unsigned int count)
+{
+        struct hvsi_struct *hp = &hvsi_ports[console->index];
+        char c[HVSI_MAX_OUTGOING_DATA] __ALIGNED__;
+        unsigned int i = 0, n = 0;
+        int ret, donecr = 0;
+
+        mb();
+        if (!is_open(hp))
+                return;
+
+        /*
+         * ugh, we have to translate LF -> CRLF ourselves, in place.
+         * copied from hvc_console.c:
+         */
+        while (count > 0 || i > 0) {
+                if (count > 0 && i < sizeof(c)) {
+                        if (buf[n] == '\n' && !donecr) {
+                                c[i++] = '\r';
+                                donecr = 1;
+                        } else {
+                                c[i++] = buf[n++];
+                                donecr = 0;
+                                --count;
+                        }
+                } else {
+                        ret = hvsi_put_chars(hp, c, i);
+                        if (ret < 0)
+                                i = 0;
+                        i -= ret;
+                }
+        }
+}
+
+static struct tty_driver *hvsi_console_device(struct console *console,
+        int *index)
+{
+        *index = console->index;
+        return hvsi_driver;
+}
+
+static int __init hvsi_console_setup(struct console *console, char *options)
+{
+        struct hvsi_struct *hp;
+        int ret;
+
+        if (console->index < 0 || console->index >= hvsi_count)
+                return -1;
+        hp = &hvsi_ports[console->index];
+
+        /* give the FSP a chance to change the baud rate when we re-open */
+        hvsi_close_protocol(hp);
+
+        ret = hvsi_handshake(hp);
+        if (ret < 0)
+                return ret;
+
+        ret = hvsi_get_mctrl(hp);
+        if (ret < 0)
+                return ret;
+
+        ret = hvsi_set_mctrl(hp, hp->mctrl | TIOCM_DTR);
+        if (ret < 0)
+                return ret;
+
+        hp->flags |= HVSI_CONSOLE;
+
+        return 0;
+}
+
+static struct console hvsi_console = {
+        .name           = "hvsi",
+        .write          = hvsi_console_print,
+        .device         = hvsi_console_device,
+        .setup          = hvsi_console_setup,
+        .flags          = CON_PRINTBUFFER,
+        .index          = -1,
+};
+
+static int __init hvsi_console_init(void)
+{
+        struct device_node *vty;
+
+        hvsi_wait = poll_for_state; /* no irqs yet; must poll */
+
+        /* search device tree for vty nodes */
+        for (vty = of_find_compatible_node(NULL, "serial", "hvterm-protocol");
+                        vty != NULL;
+                        vty = of_find_compatible_node(vty, "serial", "hvterm-protocol")) {
+                struct hvsi_struct *hp;
+                const uint32_t *vtermno, *irq;
+
+                vtermno = of_get_property(vty, "reg", NULL);
+                irq = of_get_property(vty, "interrupts", NULL);
+                if (!vtermno || !irq)
+                        continue;
+
+                if (hvsi_count >= MAX_NR_HVSI_CONSOLES) {
+                        of_node_put(vty);
+                        break;
+                }
+
+                hp = &hvsi_ports[hvsi_count];
+                INIT_DELAYED_WORK(&hp->writer, hvsi_write_worker);
+                INIT_WORK(&hp->handshaker, hvsi_handshaker);
+                init_waitqueue_head(&hp->emptyq);
+                init_waitqueue_head(&hp->stateq);
+                spin_lock_init(&hp->lock);
+                hp->index = hvsi_count;
+                hp->inbuf_end = hp->inbuf;
+                hp->state = HVSI_CLOSED;
+                hp->vtermno = *vtermno;
+                hp->virq = irq_create_mapping(NULL, irq[0]);
+                if (hp->virq == NO_IRQ) {
+                        printk(KERN_ERR "%s: couldn't create irq mapping for 0x%x\n",
+                                __func__, irq[0]);
+                        continue;
+                }
+
+                hvsi_count++;
+        }
+
+        if (hvsi_count)
+                register_console(&hvsi_console);
+        return 0;
+}
+console_initcall(hvsi_console_init);