viohs.c

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/* viohs.c: LDOM Virtual I/O handshake helper layer.
 *
 * Copyright (C) 2007 David S. Miller <[e-mail]>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/slab.h>

#include <asm/ldc.h>
#include <asm/vio.h>

int vio_ldc_send(struct vio_driver_state *vio, void *data, int len)
{
	int err, limit = 1000;

	err = -EINVAL;
	while (limit-- > 0) {
		err = ldc_write(vio->lp, data, len);
		if (!err || (err != -EAGAIN))
			break;
		udelay(1);
	}

	return err;
}
EXPORT_SYMBOL(vio_ldc_send);

static int send_ctrl(struct vio_driver_state *vio,
		     struct vio_msg_tag *tag, int len)
{
	tag->sid = vio_send_sid(vio);
	return vio_ldc_send(vio, tag, len);
}

static void init_tag(struct vio_msg_tag *tag, u8 type, u8 stype, u16 stype_env)
{
	tag->type = type;
	tag->stype = stype;
	tag->stype_env = stype_env;
}

static int send_version(struct vio_driver_state *vio, u16 major, u16 minor)
{
	struct vio_ver_info pkt;

	vio->_local_sid = (u32) sched_clock();

	memset(&pkt, 0, sizeof(pkt));
	init_tag(&pkt.tag, VIO_TYPE_CTRL, VIO_SUBTYPE_INFO, VIO_VER_INFO);
	pkt.major = major;
	pkt.minor = minor;
	pkt.dev_class = vio->dev_class;

	viodbg(HS, "SEND VERSION INFO maj[%u] min[%u] devclass[%u]\n",
	       major, minor, vio->dev_class);

	return send_ctrl(vio, &pkt.tag, sizeof(pkt));
}

static int start_handshake(struct vio_driver_state *vio)
{
	int err;

	viodbg(HS, "START HANDSHAKE\n");

	vio->hs_state = VIO_HS_INVALID;

	err = send_version(vio,
			   vio->ver_table[0].major,
			   vio->ver_table[0].minor);
	if (err < 0)
		return err;

	return 0;
}

static void flush_rx_dring(struct vio_driver_state *vio)
{
	struct vio_dring_state *dr;
	u64 ident;

	BUG_ON(!(vio->dr_state & VIO_DR_STATE_RXREG));

	dr = &vio->drings[VIO_DRIVER_RX_RING];
	ident = dr->ident;

	BUG_ON(!vio->desc_buf);
	kfree(vio->desc_buf);
	vio->desc_buf = NULL;

	memset(dr, 0, sizeof(*dr));
	dr->ident = ident;
}

void vio_link_state_change(struct vio_driver_state *vio, int event)
{
	if (event == LDC_EVENT_UP) {
		vio->hs_state = VIO_HS_INVALID;

		switch (vio->dev_class) {
		case VDEV_NETWORK:
		case VDEV_NETWORK_SWITCH:
			vio->dr_state = (VIO_DR_STATE_TXREQ |
					 VIO_DR_STATE_RXREQ);
			break;

		case VDEV_DISK:
			vio->dr_state = VIO_DR_STATE_TXREQ;
			break;
		case VDEV_DISK_SERVER:
			vio->dr_state = VIO_DR_STATE_RXREQ;
			break;
		}
		start_handshake(vio);
	} else if (event == LDC_EVENT_RESET) {
		vio->hs_state = VIO_HS_INVALID;

		if (vio->dr_state & VIO_DR_STATE_RXREG)
			flush_rx_dring(vio);

		vio->dr_state = 0x00;
		memset(&vio->ver, 0, sizeof(vio->ver));

		ldc_disconnect(vio->lp);
	}
}
EXPORT_SYMBOL(vio_link_state_change);

static int handshake_failure(struct vio_driver_state *vio)
{
	struct vio_dring_state *dr;

	/* XXX Put policy here...  Perhaps start a timer to fire
	 * XXX in 100 ms, which will bring the link up and retry
	 * XXX the handshake.
	 */

	viodbg(HS, "HANDSHAKE FAILURE\n");

	vio->dr_state &= ~(VIO_DR_STATE_TXREG |
			   VIO_DR_STATE_RXREG);

	dr = &vio->drings[VIO_DRIVER_RX_RING];
	memset(dr, 0, sizeof(*dr));

	kfree(vio->desc_buf);
	vio->desc_buf = NULL;
	vio->desc_buf_len = 0;

	vio->hs_state = VIO_HS_INVALID;

	return -ECONNRESET;
}

static int process_unknown(struct vio_driver_state *vio, void *arg)
{
	struct vio_msg_tag *pkt = arg;

	viodbg(HS, "UNKNOWN CONTROL [%02x:%02x:%04x:%08x]\n",
	       pkt->type, pkt->stype, pkt->stype_env, pkt->sid);

	printk(KERN_ERR "vio: ID[%lu] Resetting connection.\n",
	       vio->vdev->channel_id);

	ldc_disconnect(vio->lp);

	return -ECONNRESET;
}

static int send_dreg(struct vio_driver_state *vio)
{
	struct vio_dring_state *dr = &vio->drings[VIO_DRIVER_TX_RING];
	union {
		struct vio_dring_register pkt;
		char all[sizeof(struct vio_dring_register) +
			 (sizeof(struct ldc_trans_cookie) *
			  dr->ncookies)];
	} u;
	int i;

	memset(&u, 0, sizeof(u));
	init_tag(&u.pkt.tag, VIO_TYPE_CTRL, VIO_SUBTYPE_INFO, VIO_DRING_REG);
	u.pkt.dring_ident = 0;
	u.pkt.num_descr = dr->num_entries;
	u.pkt.descr_size = dr->entry_size;
	u.pkt.options = VIO_TX_DRING;
	u.pkt.num_cookies = dr->ncookies;

	viodbg(HS, "SEND DRING_REG INFO ndesc[%u] dsz[%u] opt[0x%x] "
	       "ncookies[%u]\n",
	       u.pkt.num_descr, u.pkt.descr_size, u.pkt.options,
	       u.pkt.num_cookies);

	for (i = 0; i < dr->ncookies; i++) {
		u.pkt.cookies[i] = dr->cookies[i];

		viodbg(HS, "DRING COOKIE(%d) [%016llx:%016llx]\n",
		       i,
		       (unsigned long long) u.pkt.cookies[i].cookie_addr,
		       (unsigned long long) u.pkt.cookies[i].cookie_size);
	}

	return send_ctrl(vio, &u.pkt.tag, sizeof(u));
}

static int send_rdx(struct vio_driver_state *vio)
{
	struct vio_rdx pkt;

	memset(&pkt, 0, sizeof(pkt));

	init_tag(&pkt.tag, VIO_TYPE_CTRL, VIO_SUBTYPE_INFO, VIO_RDX);

	viodbg(HS, "SEND RDX INFO\n");

	return send_ctrl(vio, &pkt.tag, sizeof(pkt));
}

static int send_attr(struct vio_driver_state *vio)
{
	return vio->ops->send_attr(vio);
}

static struct vio_version *find_by_major(struct vio_driver_state *vio,
					 u16 major)
{
	struct vio_version *ret = NULL;
	int i;

	for (i = 0; i < vio->ver_table_entries; i++) {
		struct vio_version *v = &vio->ver_table[i];
		if (v->major <= major) {
			ret = v;
			break;
		}
	}
	return ret;
}

static int process_ver_info(struct vio_driver_state *vio,
			    struct vio_ver_info *pkt)
{
	struct vio_version *vap;
	int err;

	viodbg(HS, "GOT VERSION INFO maj[%u] min[%u] devclass[%u]\n",
	       pkt->major, pkt->minor, pkt->dev_class);

	if (vio->hs_state != VIO_HS_INVALID) {
		/* XXX Perhaps invoke start_handshake? XXX */
		memset(&vio->ver, 0, sizeof(vio->ver));
		vio->hs_state = VIO_HS_INVALID;
	}

	vap = find_by_major(vio, pkt->major);

	vio->_peer_sid = pkt->tag.sid;

	if (!vap) {
		pkt->tag.stype = VIO_SUBTYPE_NACK;
		pkt->major = 0;
		pkt->minor = 0;
		viodbg(HS, "SEND VERSION NACK maj[0] min[0]\n");
		err = send_ctrl(vio, &pkt->tag, sizeof(*pkt));
	} else if (vap->major != pkt->major) {
		pkt->tag.stype = VIO_SUBTYPE_NACK;
		pkt->major = vap->major;
		pkt->minor = vap->minor;
		viodbg(HS, "SEND VERSION NACK maj[%u] min[%u]\n",
		       pkt->major, pkt->minor);
		err = send_ctrl(vio, &pkt->tag, sizeof(*pkt));
	} else {
		struct vio_version ver = {
			.major = pkt->major,
			.minor = pkt->minor,
		};
		if (ver.minor > vap->minor)
			ver.minor = vap->minor;
		pkt->minor = ver.minor;
		pkt->tag.stype = VIO_SUBTYPE_ACK;
		viodbg(HS, "SEND VERSION ACK maj[%u] min[%u]\n",
		       pkt->major, pkt->minor);
		err = send_ctrl(vio, &pkt->tag, sizeof(*pkt));
		if (err > 0) {
			vio->ver = ver;
			vio->hs_state = VIO_HS_GOTVERS;
		}
	}
	if (err < 0)
		return handshake_failure(vio);

	return 0;
}

static int process_ver_ack(struct vio_driver_state *vio,
			   struct vio_ver_info *pkt)
{
	viodbg(HS, "GOT VERSION ACK maj[%u] min[%u] devclass[%u]\n",
	       pkt->major, pkt->minor, pkt->dev_class);

	if (vio->hs_state & VIO_HS_GOTVERS) {
		if (vio->ver.major != pkt->major ||
		    vio->ver.minor != pkt->minor) {
			pkt->tag.stype = VIO_SUBTYPE_NACK;
			(void) send_ctrl(vio, &pkt->tag, sizeof(*pkt));
			return handshake_failure(vio);
		}
	} else {
		vio->ver.major = pkt->major;
		vio->ver.minor = pkt->minor;
		vio->hs_state = VIO_HS_GOTVERS;
	}

	switch (vio->dev_class) {
	case VDEV_NETWORK:
	case VDEV_DISK:
		if (send_attr(vio) < 0)
			return handshake_failure(vio);
		break;

	default:
		break;
	}

	return 0;
}

static int process_ver_nack(struct vio_driver_state *vio,
			    struct vio_ver_info *pkt)
{
	struct vio_version *nver;

	viodbg(HS, "GOT VERSION NACK maj[%u] min[%u] devclass[%u]\n",
	       pkt->major, pkt->minor, pkt->dev_class);

	if ((pkt->major == 0 && pkt->minor == 0) ||
	    !(nver = find_by_major(vio, pkt->major)))
		return handshake_failure(vio);

	if (send_version(vio, nver->major, nver->minor) < 0)
		return handshake_failure(vio);

	return 0;
}

static int process_ver(struct vio_driver_state *vio, struct vio_ver_info *pkt)
{
	switch (pkt->tag.stype) {
	case VIO_SUBTYPE_INFO:
		return process_ver_info(vio, pkt);

	case VIO_SUBTYPE_ACK:
		return process_ver_ack(vio, pkt);

	case VIO_SUBTYPE_NACK:
		return process_ver_nack(vio, pkt);

	default:
		return handshake_failure(vio);
	};
}

static int process_attr(struct vio_driver_state *vio, void *pkt)
{
	int err;

	if (!(vio->hs_state & VIO_HS_GOTVERS))
		return handshake_failure(vio);

	err = vio->ops->handle_attr(vio, pkt);
	if (err < 0) {
		return handshake_failure(vio);
	} else {
		vio->hs_state |= VIO_HS_GOT_ATTR;

		if ((vio->dr_state & VIO_DR_STATE_TXREQ) &&
		    !(vio->hs_state & VIO_HS_SENT_DREG)) {
			if (send_dreg(vio) < 0)
				return handshake_failure(vio);

			vio->hs_state |= VIO_HS_SENT_DREG;
		}
	}
	return 0;
}

static int all_drings_registered(struct vio_driver_state *vio)
{
	int need_rx, need_tx;

	need_rx = (vio->dr_state & VIO_DR_STATE_RXREQ);
	need_tx = (vio->dr_state & VIO_DR_STATE_TXREQ);

	if (need_rx &&
	    !(vio->dr_state & VIO_DR_STATE_RXREG))
		return 0;

	if (need_tx &&
	    !(vio->dr_state & VIO_DR_STATE_TXREG))
		return 0;

	return 1;
}

static int process_dreg_info(struct vio_driver_state *vio,
			     struct vio_dring_register *pkt)
{
	struct vio_dring_state *dr;