/* Copyright 2013-2016 IBM Corp.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <skiboot.h>
#include <opal-msg.h>
#include <pci-cfg.h>
#include <pci.h>
#include <pci-slot.h>

/* Debugging options */
#define PCIE_SLOT_PREFIX	"PCIE-SLOT-%016llx "
#define PCIE_SLOT_DBG(s, fmt, a...)		  \
	prlog(PR_DEBUG, PCIE_SLOT_PREFIX fmt, (s)->id, ##a)

static int64_t pcie_slot_get_presence_state(struct pci_slot *slot, uint8_t *val)
{
	struct phb *phb = slot->phb;
	struct pci_device *pd = slot->pd;
	uint32_t ecap;
	uint16_t state;

	/* The presence is always on if it's a switch upstream port */
	if (pd->dev_type == PCIE_TYPE_SWITCH_UPPORT) {
		*val = OPAL_PCI_SLOT_PRESENT;
		return OPAL_SUCCESS;
	}

	/*
	 * The presence is always on if a switch downstream port
	 * doesn't support slot capability according to PCIE spec.
	 */
	if (pd->dev_type == PCIE_TYPE_SWITCH_DNPORT &&
	    !(slot->pcie_cap & PCICAP_EXP_CAP_SLOT)) {
		*val = OPAL_PCI_SLOT_PRESENT;
		return OPAL_SUCCESS;
	}

	/* Retrieve presence status */
	ecap = pci_cap(pd, PCI_CFG_CAP_ID_EXP, false);
	pci_cfg_read16(phb, pd->bdfn, ecap + PCICAP_EXP_SLOTSTAT, &state);
	if (state & PCICAP_EXP_SLOTSTAT_PDETECTST)
		*val = OPAL_PCI_SLOT_PRESENT;
	else
		*val = OPAL_PCI_SLOT_EMPTY;

	return OPAL_SUCCESS;
}

static int64_t pcie_slot_get_link_state(struct pci_slot *slot,
					uint8_t *val)
{
	struct phb *phb = slot->phb;
	struct pci_device *pd = slot->pd;
	uint32_t ecap;
	int16_t state;

	/*
	 * The link behind switch upstream port is always on
	 * since it doesn't have a valid link indicator.
	 */
	if (pd->dev_type == PCIE_TYPE_SWITCH_UPPORT) {
		*val = 1;
		return OPAL_SUCCESS;
	}

	/* Retrieve link width */
	ecap = pci_cap(pd, PCI_CFG_CAP_ID_EXP, false);
	pci_cfg_read16(phb, pd->bdfn, ecap + PCICAP_EXP_LSTAT, &state);
	if (state & PCICAP_EXP_LSTAT_DLLL_ACT)
		*val = ((state & PCICAP_EXP_LSTAT_WIDTH) >> 4);
	else
		*val = 0;

	return OPAL_SUCCESS;
}

static int64_t pcie_slot_get_power_state(struct pci_slot *slot __unused,
					 uint8_t *val)
{
	/* We should return the cached power state that is same to
	 * the PCI slot hotplug state (added/removed). Otherwise,
	 * the OS will see mismatched states, causing the adapter
	 * behind the slot can't be probed successfully on request
	 * of hot add. So we could run into the situation where the
	 * OS sees power-off but it's on in hardware.
	 */
	*val = slot->power_state;

	return OPAL_SUCCESS;
}

static int64_t pcie_slot_get_attention_state(struct pci_slot *slot,
					     uint8_t *val)
{
	struct phb *phb = slot->phb;
	struct pci_device *pd = slot->pd;
	uint32_t ecap;
	uint16_t state;

	/* Attention is off if the capability is missing */
	if (!(slot->slot_cap & PCICAP_EXP_SLOTCAP_ATTNI)) {
		*val = 0;
		return OPAL_SUCCESS;
	}

	/* Retrieve attention state */
	ecap = pci_cap(pd, PCI_CFG_CAP_ID_EXP, false);
	pci_cfg_read16(phb, pd->bdfn, ecap + PCICAP_EXP_SLOTCTL, &state);
	state = (state & PCICAP_EXP_SLOTCTL_ATTNI) >> 6;
	switch (state) {
	case PCIE_INDIC_ON:
		*val = PCI_SLOT_ATTN_LED_ON;
		break;
	case PCIE_INDIC_BLINK:
		*val = PCI_SLOT_ATTN_LED_BLINK;
		break;
	case PCIE_INDIC_OFF:
	default:
		*val = PCI_SLOT_ATTN_LED_OFF;
	}

	return OPAL_SUCCESS;
}

static int64_t pcie_slot_get_latch_state(struct pci_slot *slot,
					 uint8_t *val)
{
	struct phb *phb = slot->phb;
	struct pci_device *pd = slot->pd;
	uint32_t ecap;
	uint16_t state;

	/* Latch is off if MRL sensor doesn't exist */
	if (!(slot->slot_cap & PCICAP_EXP_SLOTCAP_MRLSENS)) {
		*val = 0;
		return OPAL_SUCCESS;
	}

	/* Retrieve MRL sensor state */
	ecap = pci_cap(pd, PCI_CFG_CAP_ID_EXP, false);
	pci_cfg_read16(phb, pd->bdfn, ecap + PCICAP_EXP_SLOTSTAT, &state);
	if (state & PCICAP_EXP_SLOTSTAT_MRLSENSST)
		*val = 1;
	else
		*val = 0;

	return OPAL_SUCCESS;
}

static int64_t pcie_slot_set_attention_state(struct pci_slot *slot,
					     uint8_t val)
{
	struct phb *phb = slot->phb;
	struct pci_device *pd = slot->pd;
	uint32_t ecap;
	uint16_t state;

	/* Drop the request if functionality doesn't exist */
	if (!(slot->slot_cap & PCICAP_EXP_SLOTCAP_ATTNI))
		return OPAL_SUCCESS;

	/* Update with the requested state */
	ecap = pci_cap(pd, PCI_CFG_CAP_ID_EXP, false);
	pci_cfg_read16(phb, pd->bdfn, ecap + PCICAP_EXP_SLOTCTL, &state);
	state &= ~PCICAP_EXP_SLOTCTL_ATTNI;
	switch (val) {
	case PCI_SLOT_ATTN_LED_ON:
		state |= (PCIE_INDIC_ON << 6);
		break;
	case PCI_SLOT_ATTN_LED_BLINK:
		state |= (PCIE_INDIC_BLINK << 6);
		break;
	case PCI_SLOT_ATTN_LED_OFF:
		state |= (PCIE_INDIC_OFF << 6);
		break;
	default:
		prlog(PR_ERR, PCIE_SLOT_PREFIX
		      "Invalid attention state (0x%x)\n", slot->id, val);
		return OPAL_PARAMETER;
	}

	pci_cfg_write16(phb, pd->bdfn, ecap + PCICAP_EXP_SLOTCTL, state);
	return OPAL_SUCCESS;
}

static int64_t pcie_slot_set_power_state_ext(struct pci_slot *slot, uint8_t val,
					     bool surprise_check)
{
	struct phb *phb = slot->phb;
	struct pci_device *pd = slot->pd;
	uint32_t ecap;
	uint16_t state;

	if (slot->power_state == val)
		return OPAL_SUCCESS;

	/* Update the power state and return immediately if the power
	 * control functionality isn't supported on the PCI slot.
	 */
	if (!(slot->slot_cap & PCICAP_EXP_SLOTCAP_PWCTRL)) {
		slot->power_state = val;
		return OPAL_SUCCESS;
	}

	/*
	 * Suprise hotpluggable slots need to be handled with care since
	 * many systems do not implement the presence detect side-band
	 * signal. Instead, they rely on in-band presence to report the
	 * existence of a hotplugged card.
	 *
	 * This is problematic because:
	 * a) When PERST is asserted in-band presence doesn't work, and
	 * b) Switches assert PERST as a part of the "slot power down" sequence
	 *
	 * To work around the problem we leave the slot physically powered on
	 * and exit early here. This way when a new card is inserted, the switch
	 * will raise an interrupt due to the PresDet status changing.
	 */
	if (surprise_check && slot->surprise_pluggable) {
		slot->power_state = val;
		if (val == PCI_SLOT_POWER_OFF)
			return OPAL_SUCCESS;

		/*
		 * Some systems have the slot power disabled by default
		 * so we always perform the power-on step. This is not
		 * *strictly* required, but it's probably a good idea.
		 */
	}

	pci_slot_set_state(slot, PCI_SLOT_STATE_SPOWER_START);
	slot->power_state = val;
	ecap = pci_cap(pd, PCI_CFG_CAP_ID_EXP, false);
	pci_cfg_read16(phb, pd->bdfn, ecap + PCICAP_EXP_SLOTCTL, &state);
	state &= ~(PCICAP_EXP_SLOTCTL_PWRCTLR | PCICAP_EXP_SLOTCTL_PWRI);
	switch (val) {
	case PCI_SLOT_POWER_OFF:
		state |= (PCICAP_EXP_SLOTCTL_PWRCTLR | (PCIE_INDIC_OFF << 8));
		break;
	case PCI_SLOT_POWER_ON:
		state |= (PCIE_INDIC_ON << 8);
		break;
	default:
		pci_slot_set_state(slot, PCI_SLOT_STATE_NORMAL);
		prlog(PR_ERR, PCIE_SLOT_PREFIX
		      "Invalid power state (0x%x)\n", slot->id, val);
		return OPAL_PARAMETER;
	}

	pci_cfg_write16(phb, pd->bdfn, ecap + PCICAP_EXP_SLOTCTL, state);
	pci_slot_set_state(slot, PCI_SLOT_STATE_SPOWER_DONE);

	return OPAL_ASYNC_COMPLETION;
}

static int64_t pcie_slot_set_power_state(struct pci_slot *slot, uint8_t val)
{
	return pcie_slot_set_power_state_ext(slot, val, true);
}

static int64_t pcie_slot_sm_poll_link(struct pci_slot *slot)
{
	struct phb *phb = slot->phb;
	struct pci_device *pd = slot->pd;
	uint32_t ecap = pci_cap(pd, PCI_CFG_CAP_ID_EXP, false);
	uint16_t val;
	uint8_t presence = 0;

	switch (slot->state) {
	case PCI_SLOT_STATE_LINK_START_POLL:
		PCIE_SLOT_DBG(slot, "LINK: Start polling\n");

		/* Link is down for ever without devices attached */
		if (slot->ops.get_presence_state)
			slot->ops.get_presence_state(slot, &presence);
		if (!presence) {
			PCIE_SLOT_DBG(slot, "LINK: No adapter, end polling\n");
			pci_slot_set_state(slot, PCI_SLOT_STATE_NORMAL);
			return OPAL_SUCCESS;
		}

		/* Enable the link without check */
		pci_cfg_read16(phb, pd->bdfn, ecap + PCICAP_EXP_LCTL, &val);
		val &= ~PCICAP_EXP_LCTL_LINK_DIS;
		pci_cfg_write16(phb, pd->bdfn, ecap + PCICAP_EXP_LCTL, val);

		/*
		 * If the link change report isn't supported, we expect
		 * the link is up and stabilized after one second.
		 */
		if (!(slot->link_cap & PCICAP_EXP_LCAP_DL_ACT_REP)) {
			pci_slot_set_state(slot,
					   PCI_SLOT_STATE_LINK_DELAY_FINALIZED);
			return pci_slot_set_sm_timeout(slot, secs_to_tb(1));
		}

		/*
		 * Poll the link state if link state change report is
		 * supported on the link.
		 */
		pci_slot_set_state(slot, PCI_SLOT_STATE_LINK_POLLING);
		slot->retries = 250;
		return pci_slot_set_sm_timeout(slot, msecs_to_tb(20));
	case PCI_SLOT_STATE_LINK_DELAY_FINALIZED:
		PCIE_SLOT_DBG(slot, "LINK: No link report, end polling\n");
		if (slot->ops.prepare_link_change)
			slot->ops.prepare_link_change(slot, true);
		pci_slot_set_state(slot, PCI_SLOT_STATE_NORMAL);
		return OPAL_SUCCESS;
	case PCI_SLOT_STATE_LINK_POLLING:
		pci_cfg_read16(phb, pd->bdfn, ecap + PCICAP_EXP_LSTAT, &val);
		if (val & PCICAP_EXP_LSTAT_DLLL_ACT) {
			PCIE_SLOT_DBG(slot, "LINK: Link is up, end polling\n");
			if (slot->ops.prepare_link_change)
				slot->ops.prepare_link_change(slot, true);
			pci_slot_set_state(slot, PCI_SLOT_STATE_NORMAL);
			return OPAL_SUCCESS;
		}

		/* Check link state again until timeout */
		if (slot->retries-- == 0) {
			prlog(PR_ERR, PCIE_SLOT_PREFIX
			      "LINK: Timeout waiting for up (%04x)\n",
			      slot->id, val);
			pci_slot_set_state(slot, PCI_SLOT_STATE_NORMAL);
			return OPAL_SUCCESS;
		}

		return pci_slot_set_sm_timeout(slot, msecs_to_tb(20));
	default:
		prlog(PR_ERR, PCIE_SLOT_PREFIX
		      "Link: Unexpected slot state %08x\n",
		      slot->id, slot->state);
	}

	pci_slot_set_state(slot, PCI_SLOT_STATE_NORMAL);
	return OPAL_HARDWARE;
}

static void pcie_slot_reset(struct pci_slot *slot, bool assert)
{
	struct phb *phb = slot->phb;
	struct pci_device *pd = slot->pd;
	uint16_t ctl;

	pci_cfg_read16(phb, pd->bdfn, PCI_CFG_BRCTL, &ctl);
	if (assert)
		ctl |= PCI_CFG_BRCTL_SECONDARY_RESET;
	else
		ctl &= ~PCI_CFG_BRCTL_SECONDARY_RESET;
	pci_cfg_write16(phb, pd->bdfn, PCI_CFG_BRCTL, ctl);
}

static int64_t pcie_slot_sm_hreset(struct pci_slot *slot)
{
	switch (slot->state) {
	case PCI_SLOT_STATE_NORMAL:
		PCIE_SLOT_DBG(slot, "HRESET: Starts\n");
		if (slot->ops.prepare_link_change) {
			PCIE_SLOT_DBG(slot, "HRESET: Prepare for link down\n");
			slot->ops.prepare_link_change(slot, false);
		}
		/* fall through */
	case PCI_SLOT_STATE_HRESET_START:
		PCIE_SLOT_DBG(slot, "HRESET: Assert\n");
		pcie_slot_reset(slot, true);
		pci_slot_set_state(slot, PCI_SLOT_STATE_HRESET_HOLD);
		return pci_slot_set_sm_timeout(slot, msecs_to_tb(250));
	case PCI_SLOT_STATE_HRESET_HOLD:
		PCIE_SLOT_DBG(slot, "HRESET: Deassert\n");
		pcie_slot_reset(slot, false);
		pci_slot_set_state(slot, PCI_SLOT_STATE_LINK_START_POLL);
		return pci_slot_set_sm_timeout(slot, msecs_to_tb(1800));
	default:
		PCIE_SLOT_DBG(slot, "HRESET: Unexpected slot state %08x\n",
			      slot->state);
	}

	pci_slot_set_state(slot, PCI_SLOT_STATE_NORMAL);
	return OPAL_HARDWARE;
}

/*
 * Usually, individual platforms need to override the power
 * management methods for fundamental reset, but the hot
 * reset method is commonly shared.
 */
static int64_t pcie_slot_sm_freset(struct pci_slot *slot)
{
	uint8_t power_state = PCI_SLOT_POWER_ON;

	switch (slot->state) {
	case PCI_SLOT_STATE_NORMAL:
		PCIE_SLOT_DBG(slot, "FRESET: Starts\n");
		if (slot->ops.prepare_link_change)
			slot->ops.prepare_link_change(slot, false);

		/* Retrieve power state */
		if (slot->ops.get_power_state) {
			PCIE_SLOT_DBG(slot, "FRESET: Retrieve power state\n");
			slot->ops.get_power_state(slot, &power_state);
		}

		/* In power on state, power it off */
		if (power_state == PCI_SLOT_POWER_ON) {
			PCIE_SLOT_DBG(slot, "FRESET: Power is on, turn off\n");
			pcie_slot_set_power_state_ext(slot,
				PCI_SLOT_POWER_OFF, false);
			pci_slot_set_state(slot,
				PCI_SLOT_STATE_FRESET_POWER_OFF);
			return pci_slot_set_sm_timeout(slot, msecs_to_tb(50));
		}
		/* No power state change, */
		/* fallthrough */
	case PCI_SLOT_STATE_FRESET_POWER_OFF:
		PCIE_SLOT_DBG(slot, "FRESET: Power is off, turn on\n");
		pcie_slot_set_power_state_ext(slot, PCI_SLOT_POWER_ON, false);

		pci_slot_set_state(slot, PCI_SLOT_STATE_LINK_START_POLL);
		return pci_slot_set_sm_timeout(slot, msecs_to_tb(50));
	default:
		prlog(PR_ERR, PCIE_SLOT_PREFIX
		      "FRESET: Unexpected slot state %08x\n",
		      slot->id, slot->state);
	}

	pci_slot_set_state(slot, PCI_SLOT_STATE_NORMAL);
	return OPAL_HARDWARE;
}

struct pci_slot *pcie_slot_create(struct phb *phb, struct pci_device *pd)
{
	struct pci_slot *slot;
	uint32_t ecap;
	uint16_t slot_ctl;

	/* Allocate PCI slot */
	slot = pci_slot_alloc(phb, pd);
	if (!slot)
		return NULL;

	/* Cache the link and slot capabilities */
	ecap = pci_cap(pd, PCI_CFG_CAP_ID_EXP, false);
	pci_cfg_read16(phb, pd->bdfn, ecap + PCICAP_EXP_CAPABILITY_REG,
		       &slot->pcie_cap);
	pci_cfg_read32(phb, pd->bdfn, ecap + PCICAP_EXP_LCAP,
		       &slot->link_cap);

	/* Leave PCI slot capability blank if PCI slot isn't supported */
	if (slot->pcie_cap & PCICAP_EXP_CAP_SLOT)
		pci_cfg_read32(phb, pd->bdfn, ecap + PCICAP_EXP_SLOTCAP,
			       &slot->slot_cap);
	else
		slot->slot_cap = 0;

	if (slot->slot_cap & PCICAP_EXP_SLOTCAP_HPLUG_CAP)
		slot->pluggable = 1;

	/* Assume the slot is powered on by default */
	slot->power_state = PCI_SLOT_POWER_ON;
	if (slot->slot_cap & PCICAP_EXP_SLOTCAP_PWCTRL) {
		slot->power_ctl = 1;

		pci_cfg_read16(phb, pd->bdfn, ecap + PCICAP_EXP_SLOTCTL,
			       &slot_ctl);
		if (slot_ctl & PCICAP_EXP_SLOTCTL_PWRCTLR)
			slot->power_state = PCI_SLOT_POWER_OFF;
	}

	if (slot->slot_cap & PCICAP_EXP_SLOTCAP_PWRI)
		slot->power_led_ctl = PCI_SLOT_PWR_LED_CTL_KERNEL;
	if (slot->slot_cap & PCICAP_EXP_SLOTCAP_ATTNI)
		slot->attn_led_ctl = PCI_SLOT_ATTN_LED_CTL_KERNEL;
	slot->wired_lanes = ((slot->link_cap & PCICAP_EXP_LCAP_MAXWDTH) >> 4);

	/* The surprise hotplug capability is claimed when it's supported
	 * in the slot's capability bits or link state change reporting is
	 * supported in PCIe link capability. It means the surprise hotplug
	 * relies on presence or link state change events. In order for the
	 * link state change event to be properly raised during surprise hot
	 * add/remove, the power supply to the slot should be always on.
	 *
	 * For PCI slots that don't claim surprise hotplug capability explicitly.
	 * Its PDC (Presence Detection Change) isn't reliable. To mark that as
	 * broken on them.
	 */
	if (slot->pcie_cap & PCICAP_EXP_CAP_SLOT) {
		if (slot->slot_cap & PCICAP_EXP_SLOTCAP_HPLUG_SURP) {
			slot->surprise_pluggable = 1;
		} else if (slot->link_cap & PCICAP_EXP_LCAP_DL_ACT_REP) {
			slot->surprise_pluggable = 1;

			pci_slot_add_flags(slot, PCI_SLOT_FLAG_BROKEN_PDC);
		}
	}

	/* Standard slot operations */
	slot->ops.get_presence_state  = pcie_slot_get_presence_state;
	slot->ops.get_link_state      = pcie_slot_get_link_state;
	slot->ops.get_power_state     = pcie_slot_get_power_state;
	slot->ops.get_attention_state = pcie_slot_get_attention_state;
	slot->ops.get_latch_state     = pcie_slot_get_latch_state;
	slot->ops.set_power_state     = pcie_slot_set_power_state;
	slot->ops.set_attention_state = pcie_slot_set_attention_state;

	/*
	 * State machine (SM) based reset stuff. The poll function is always
	 * unified for all cases.
	 */
	slot->ops.poll_link             = pcie_slot_sm_poll_link;
	slot->ops.hreset                = pcie_slot_sm_hreset;
	slot->ops.freset                = pcie_slot_sm_freset;

	slot->wired_lanes    = PCI_SLOT_WIRED_LANES_UNKNOWN;
	slot->connector_type = PCI_SLOT_CONNECTOR_PCIE_NS;
	slot->card_desc      = PCI_SLOT_DESC_NON_STANDARD;
	slot->card_mech      = PCI_SLOT_MECH_NONE;
	slot->power_led_ctl  = PCI_SLOT_PWR_LED_CTL_NONE;
	slot->attn_led_ctl   = PCI_SLOT_ATTN_LED_CTL_NONE;

	return slot;
}

/* FIXME: this is kind of insane */
struct pci_slot *pcie_slot_create_dynamic(struct phb *phb,
		struct pci_device *pd)
{
	uint32_t ecap, val;
	struct pci_slot *slot;

	if (!phb || !pd || pd->slot)
		return NULL;

	/* Try to create slot whose details aren't provided by platform.
	 * We only care the downstream ports of PCIe switch that connects
	 * to root port.
	 */
	if (pd->dev_type != PCIE_TYPE_SWITCH_DNPORT ||
	    !pd->parent || !pd->parent->parent ||
	    pd->parent->parent->parent)
		return NULL;

	ecap = pci_cap(pd, PCI_CFG_CAP_ID_EXP, false);
	pci_cfg_read32(phb, pd->bdfn, ecap + PCICAP_EXP_SLOTCAP, &val);
	if (!(val & PCICAP_EXP_SLOTCAP_HPLUG_CAP))
		return NULL;

	slot = pcie_slot_create(phb, pd);

	/* On superMicro's "p8dnu" platform, we create dynamic PCI slots
	 * for all downstream ports of PEX9733 that is connected to PHB
	 * direct slot. The power supply to the PCI slot is lost after
	 * PCI adapter is removed from it. The power supply can't be
	 * turned on when the slot is in empty state. The power supply
	 * isn't turned on automatically when inserting PCI adapter to
	 * the slot at later point. We set a flag to the slot here, to
	 * turn on the power supply in (suprise or managed) hot-add path.
	 *
	 * We have same issue with PEX8718 as above on "p8dnu" platform.
	 */
	if (dt_node_is_compatible(dt_root, "supermicro,p8dnu") && slot &&
	    slot->pd && (slot->pd->vdid == 0x973310b5 ||
	    slot->pd->vdid == 0x871810b5))
		pci_slot_add_flags(slot, PCI_SLOT_FLAG_FORCE_POWERON);

	return slot;
}