From: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.com
Handle Xen event channels: - create for all configured connectors and publish corresponding ring references and event channels in Xen store, so backend can connect - implement event channels interrupt handlers - create and destroy event channels with respect to Xen bus state
Signed-off-by: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.com --- drivers/gpu/drm/xen/Makefile | 1 + drivers/gpu/drm/xen/xen_drm_front.c | 12 +- drivers/gpu/drm/xen/xen_drm_front.h | 16 ++ drivers/gpu/drm/xen/xen_drm_front_evtchnl.c | 381 ++++++++++++++++++++++++++++ drivers/gpu/drm/xen/xen_drm_front_evtchnl.h | 79 ++++++ 5 files changed, 488 insertions(+), 1 deletion(-) create mode 100644 drivers/gpu/drm/xen/xen_drm_front_evtchnl.c create mode 100644 drivers/gpu/drm/xen/xen_drm_front_evtchnl.h
diff --git a/drivers/gpu/drm/xen/Makefile b/drivers/gpu/drm/xen/Makefile index d3ec8c8589e0..8417332f3b58 100644 --- a/drivers/gpu/drm/xen/Makefile +++ b/drivers/gpu/drm/xen/Makefile @@ -1,6 +1,7 @@ # SPDX-License-Identifier: GPL-2.0 OR MIT
drm_xen_front-objs := xen_drm_front.o \ + xen_drm_front_evtchnl.o \ xen_drm_front_cfg.o
obj-$(CONFIG_DRM_XEN_FRONTEND) += drm_xen_front.o diff --git a/drivers/gpu/drm/xen/xen_drm_front.c b/drivers/gpu/drm/xen/xen_drm_front.c index ca42ceb24a40..8312dab862e2 100644 --- a/drivers/gpu/drm/xen/xen_drm_front.c +++ b/drivers/gpu/drm/xen/xen_drm_front.c @@ -17,9 +17,11 @@ #include <xen/interface/io/displif.h>
#include "xen_drm_front.h" +#include "xen_drm_front_evtchnl.h"
static void xen_drv_remove_internal(struct xen_drm_front_info *front_info) { + xen_drm_front_evtchnl_free_all(front_info); }
static int displback_initwait(struct xen_drm_front_info *front_info) @@ -33,16 +35,23 @@ static int displback_initwait(struct xen_drm_front_info *front_info) return ret;
DRM_INFO("Have %d conector(s)\n", cfg->num_connectors); - return 0; + /* Create event channels for all connectors and publish */ + ret = xen_drm_front_evtchnl_create_all(front_info); + if (ret < 0) + return ret; + + return xen_drm_front_evtchnl_publish_all(front_info); }
static int displback_connect(struct xen_drm_front_info *front_info) { + xen_drm_front_evtchnl_set_state(front_info, EVTCHNL_STATE_CONNECTED); return 0; }
static void displback_disconnect(struct xen_drm_front_info *front_info) { + xen_drm_front_evtchnl_set_state(front_info, EVTCHNL_STATE_DISCONNECTED); xenbus_switch_state(front_info->xb_dev, XenbusStateInitialising); }
@@ -125,6 +134,7 @@ static int xen_drv_probe(struct xenbus_device *xb_dev, return -ENOMEM;
front_info->xb_dev = xb_dev; + spin_lock_init(&front_info->io_lock); dev_set_drvdata(&xb_dev->dev, front_info); return xenbus_switch_state(xb_dev, XenbusStateInitialising); } diff --git a/drivers/gpu/drm/xen/xen_drm_front.h b/drivers/gpu/drm/xen/xen_drm_front.h index 034a3987657e..4adb6101c889 100644 --- a/drivers/gpu/drm/xen/xen_drm_front.h +++ b/drivers/gpu/drm/xen/xen_drm_front.h @@ -13,8 +13,24 @@
#include "xen_drm_front_cfg.h"
+#ifndef GRANT_INVALID_REF +/* + * Note on usage of grant reference 0 as invalid grant reference: + * grant reference 0 is valid, but never exposed to a PV driver, + * because of the fact it is already in use/reserved by the PV console. + */ +#define GRANT_INVALID_REF 0 +#endif + struct xen_drm_front_info { struct xenbus_device *xb_dev; + /* to protect data between backend IO code and interrupt handler */ + spinlock_t io_lock; + /* virtual DRM platform device */ + struct platform_device *drm_pdev; + + int num_evt_pairs; + struct xen_drm_front_evtchnl_pair *evt_pairs; struct xen_drm_front_cfg cfg; };
diff --git a/drivers/gpu/drm/xen/xen_drm_front_evtchnl.c b/drivers/gpu/drm/xen/xen_drm_front_evtchnl.c new file mode 100644 index 000000000000..fd9289a6a1c8 --- /dev/null +++ b/drivers/gpu/drm/xen/xen_drm_front_evtchnl.c @@ -0,0 +1,381 @@ +// SPDX-License-Identifier: GPL-2.0 OR MIT + +/* + * Xen para-virtual DRM device + * + * Copyright (C) 2016-2018 EPAM Systems Inc. + * + * Author: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.com + */ + +#include <drm/drmP.h> + +#include <linux/errno.h> +#include <linux/irq.h> + +#include <xen/xenbus.h> +#include <xen/events.h> +#include <xen/grant_table.h> + +#include "xen_drm_front.h" +#include "xen_drm_front_evtchnl.h" + +static irqreturn_t evtchnl_interrupt_ctrl(int irq, void *dev_id) +{ + struct xen_drm_front_evtchnl *evtchnl = dev_id; + struct xen_drm_front_info *front_info = evtchnl->front_info; + struct xendispl_resp *resp; + RING_IDX i, rp; + unsigned long flags; + + if (unlikely(evtchnl->state != EVTCHNL_STATE_CONNECTED)) + return IRQ_HANDLED; + + spin_lock_irqsave(&front_info->io_lock, flags); + +again: + rp = evtchnl->u.req.ring.sring->rsp_prod; + /* ensure we see queued responses up to rp */ + virt_rmb(); + + for (i = evtchnl->u.req.ring.rsp_cons; i != rp; i++) { + resp = RING_GET_RESPONSE(&evtchnl->u.req.ring, i); + if (unlikely(resp->id != evtchnl->evt_id)) + continue; + + switch (resp->operation) { + case XENDISPL_OP_PG_FLIP: + case XENDISPL_OP_FB_ATTACH: + case XENDISPL_OP_FB_DETACH: + case XENDISPL_OP_DBUF_CREATE: + case XENDISPL_OP_DBUF_DESTROY: + case XENDISPL_OP_SET_CONFIG: + evtchnl->u.req.resp_status = resp->status; + complete(&evtchnl->u.req.completion); + break; + + default: + DRM_ERROR("Operation %d is not supported\n", + resp->operation); + break; + } + } + + evtchnl->u.req.ring.rsp_cons = i; + + if (i != evtchnl->u.req.ring.req_prod_pvt) { + int more_to_do; + + RING_FINAL_CHECK_FOR_RESPONSES(&evtchnl->u.req.ring, + more_to_do); + if (more_to_do) + goto again; + } else + evtchnl->u.req.ring.sring->rsp_event = i + 1; + + spin_unlock_irqrestore(&front_info->io_lock, flags); + return IRQ_HANDLED; +} + +static irqreturn_t evtchnl_interrupt_evt(int irq, void *dev_id) +{ + struct xen_drm_front_evtchnl *evtchnl = dev_id; + struct xen_drm_front_info *front_info = evtchnl->front_info; + struct xendispl_event_page *page = evtchnl->u.evt.page; + uint32_t cons, prod; + unsigned long flags; + + if (unlikely(evtchnl->state != EVTCHNL_STATE_CONNECTED)) + return IRQ_HANDLED; + + spin_lock_irqsave(&front_info->io_lock, flags); + + prod = page->in_prod; + /* ensure we see ring contents up to prod */ + virt_rmb(); + if (prod == page->in_cons) + goto out; + + for (cons = page->in_cons; cons != prod; cons++) { + struct xendispl_evt *event; + + event = &XENDISPL_IN_RING_REF(page, cons); + if (unlikely(event->id != evtchnl->evt_id++)) + continue; + + switch (event->type) { + case XENDISPL_EVT_PG_FLIP: + /* placeholder */ + break; + } + } + page->in_cons = cons; + /* ensure ring contents */ + virt_wmb(); + +out: + spin_unlock_irqrestore(&front_info->io_lock, flags); + return IRQ_HANDLED; +} + +static void evtchnl_free(struct xen_drm_front_info *front_info, + struct xen_drm_front_evtchnl *evtchnl) +{ + unsigned long page = 0; + + if (evtchnl->type == EVTCHNL_TYPE_REQ) + page = (unsigned long)evtchnl->u.req.ring.sring; + else if (evtchnl->type == EVTCHNL_TYPE_EVT) + page = (unsigned long)evtchnl->u.evt.page; + if (!page) + return; + + evtchnl->state = EVTCHNL_STATE_DISCONNECTED; + + if (evtchnl->type == EVTCHNL_TYPE_REQ) { + /* release all who still waits for response if any */ + evtchnl->u.req.resp_status = -EIO; + complete_all(&evtchnl->u.req.completion); + } + + if (evtchnl->irq) + unbind_from_irqhandler(evtchnl->irq, evtchnl); + + if (evtchnl->port) + xenbus_free_evtchn(front_info->xb_dev, evtchnl->port); + + /* end access and free the page */ + if (evtchnl->gref != GRANT_INVALID_REF) + gnttab_end_foreign_access(evtchnl->gref, 0, page); + + memset(evtchnl, 0, sizeof(*evtchnl)); +} + +static int evtchnl_alloc(struct xen_drm_front_info *front_info, int index, + struct xen_drm_front_evtchnl *evtchnl, + enum xen_drm_front_evtchnl_type type) +{ + struct xenbus_device *xb_dev = front_info->xb_dev; + unsigned long page; + grant_ref_t gref; + irq_handler_t handler; + int ret; + + memset(evtchnl, 0, sizeof(*evtchnl)); + evtchnl->type = type; + evtchnl->index = index; + evtchnl->front_info = front_info; + evtchnl->state = EVTCHNL_STATE_DISCONNECTED; + evtchnl->gref = GRANT_INVALID_REF; + + page = get_zeroed_page(GFP_NOIO | __GFP_HIGH); + if (!page) { + ret = -ENOMEM; + goto fail; + } + + if (type == EVTCHNL_TYPE_REQ) { + struct xen_displif_sring *sring; + + init_completion(&evtchnl->u.req.completion); + sring = (struct xen_displif_sring *)page; + SHARED_RING_INIT(sring); + FRONT_RING_INIT(&evtchnl->u.req.ring, + sring, XEN_PAGE_SIZE); + + ret = xenbus_grant_ring(xb_dev, sring, 1, &gref); + if (ret < 0) + goto fail; + + handler = evtchnl_interrupt_ctrl; + } else { + evtchnl->u.evt.page = (struct xendispl_event_page *)page; + + ret = gnttab_grant_foreign_access(xb_dev->otherend_id, + virt_to_gfn((void *)page), 0); + if (ret < 0) + goto fail; + + gref = ret; + handler = evtchnl_interrupt_evt; + } + evtchnl->gref = gref; + + ret = xenbus_alloc_evtchn(xb_dev, &evtchnl->port); + if (ret < 0) + goto fail; + + ret = bind_evtchn_to_irqhandler(evtchnl->port, + handler, 0, xb_dev->devicetype, evtchnl); + if (ret < 0) + goto fail; + + evtchnl->irq = ret; + return 0; + +fail: + DRM_ERROR("Failed to allocate ring: %d\n", ret); + return ret; +} + +int xen_drm_front_evtchnl_create_all(struct xen_drm_front_info *front_info) +{ + struct xen_drm_front_cfg *cfg; + int ret, conn; + + cfg = &front_info->cfg; + + front_info->evt_pairs = devm_kcalloc(&front_info->xb_dev->dev, + cfg->num_connectors, + sizeof(struct xen_drm_front_evtchnl_pair), GFP_KERNEL); + if (!front_info->evt_pairs) { + ret = -ENOMEM; + goto fail; + } + + for (conn = 0; conn < cfg->num_connectors; conn++) { + ret = evtchnl_alloc(front_info, conn, + &front_info->evt_pairs[conn].req, + EVTCHNL_TYPE_REQ); + if (ret < 0) { + DRM_ERROR("Error allocating control channel\n"); + goto fail; + } + + ret = evtchnl_alloc(front_info, conn, + &front_info->evt_pairs[conn].evt, + EVTCHNL_TYPE_EVT); + if (ret < 0) { + DRM_ERROR("Error allocating in-event channel\n"); + goto fail; + } + } + front_info->num_evt_pairs = cfg->num_connectors; + return 0; + +fail: + xen_drm_front_evtchnl_free_all(front_info); + return ret; +} + +static int evtchnl_publish(struct xenbus_transaction xbt, + struct xen_drm_front_evtchnl *evtchnl, const char *path, + const char *node_ring, const char *node_chnl) +{ + struct xenbus_device *xb_dev = evtchnl->front_info->xb_dev; + int ret; + + /* write control channel ring reference */ + ret = xenbus_printf(xbt, path, node_ring, "%u", evtchnl->gref); + if (ret < 0) { + xenbus_dev_error(xb_dev, ret, "writing ring-ref"); + return ret; + } + + /* write event channel ring reference */ + ret = xenbus_printf(xbt, path, node_chnl, "%u", evtchnl->port); + if (ret < 0) { + xenbus_dev_error(xb_dev, ret, "writing event channel"); + return ret; + } + + return 0; +} + +int xen_drm_front_evtchnl_publish_all(struct xen_drm_front_info *front_info) +{ + struct xenbus_transaction xbt; + struct xen_drm_front_cfg *plat_data; + int ret, conn; + + plat_data = &front_info->cfg; + +again: + ret = xenbus_transaction_start(&xbt); + if (ret < 0) { + xenbus_dev_fatal(front_info->xb_dev, ret, + "starting transaction"); + return ret; + } + + for (conn = 0; conn < plat_data->num_connectors; conn++) { + ret = evtchnl_publish(xbt, + &front_info->evt_pairs[conn].req, + plat_data->connectors[conn].xenstore_path, + XENDISPL_FIELD_REQ_RING_REF, + XENDISPL_FIELD_REQ_CHANNEL); + if (ret < 0) + goto fail; + + ret = evtchnl_publish(xbt, + &front_info->evt_pairs[conn].evt, + plat_data->connectors[conn].xenstore_path, + XENDISPL_FIELD_EVT_RING_REF, + XENDISPL_FIELD_EVT_CHANNEL); + if (ret < 0) + goto fail; + } + + ret = xenbus_transaction_end(xbt, 0); + if (ret < 0) { + if (ret == -EAGAIN) + goto again; + + xenbus_dev_fatal(front_info->xb_dev, ret, + "completing transaction"); + goto fail_to_end; + } + + return 0; + +fail: + xenbus_transaction_end(xbt, 1); + +fail_to_end: + xenbus_dev_fatal(front_info->xb_dev, ret, "writing Xen store"); + return ret; +} + +void xen_drm_front_evtchnl_flush(struct xen_drm_front_evtchnl *evtchnl) +{ + int notify; + + evtchnl->u.req.ring.req_prod_pvt++; + RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&evtchnl->u.req.ring, notify); + if (notify) + notify_remote_via_irq(evtchnl->irq); +} + +void xen_drm_front_evtchnl_set_state(struct xen_drm_front_info *front_info, + enum xen_drm_front_evtchnl_state state) +{ + unsigned long flags; + int i; + + if (!front_info->evt_pairs) + return; + + spin_lock_irqsave(&front_info->io_lock, flags); + for (i = 0; i < front_info->num_evt_pairs; i++) { + front_info->evt_pairs[i].req.state = state; + front_info->evt_pairs[i].evt.state = state; + } + spin_unlock_irqrestore(&front_info->io_lock, flags); + +} + +void xen_drm_front_evtchnl_free_all(struct xen_drm_front_info *front_info) +{ + int i; + + if (!front_info->evt_pairs) + return; + + for (i = 0; i < front_info->num_evt_pairs; i++) { + evtchnl_free(front_info, &front_info->evt_pairs[i].req); + evtchnl_free(front_info, &front_info->evt_pairs[i].evt); + } + + devm_kfree(&front_info->xb_dev->dev, front_info->evt_pairs); + front_info->evt_pairs = NULL; +} diff --git a/drivers/gpu/drm/xen/xen_drm_front_evtchnl.h b/drivers/gpu/drm/xen/xen_drm_front_evtchnl.h new file mode 100644 index 000000000000..8faacf9444e6 --- /dev/null +++ b/drivers/gpu/drm/xen/xen_drm_front_evtchnl.h @@ -0,0 +1,79 @@ +/* SPDX-License-Identifier: GPL-2.0 OR MIT */ + +/* + * Xen para-virtual DRM device + * + * Copyright (C) 2016-2018 EPAM Systems Inc. + * + * Author: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.com + */ + +#ifndef __XEN_DRM_FRONT_EVTCHNL_H_ +#define __XEN_DRM_FRONT_EVTCHNL_H_ + +#include <linux/completion.h> +#include <linux/types.h> + +#include <xen/interface/io/ring.h> +#include <xen/interface/io/displif.h> + +/* + * All operations which are not connector oriented use this ctrl event channel, + * e.g. fb_attach/destroy which belong to a DRM device, not to a CRTC. + */ +#define GENERIC_OP_EVT_CHNL 0 + +enum xen_drm_front_evtchnl_state { + EVTCHNL_STATE_DISCONNECTED, + EVTCHNL_STATE_CONNECTED, +}; + +enum xen_drm_front_evtchnl_type { + EVTCHNL_TYPE_REQ, + EVTCHNL_TYPE_EVT, +}; + +struct xen_drm_front_drm_info; + +struct xen_drm_front_evtchnl { + struct xen_drm_front_info *front_info; + int gref; + int port; + int irq; + int index; + enum xen_drm_front_evtchnl_state state; + enum xen_drm_front_evtchnl_type type; + /* either response id or incoming event id */ + uint16_t evt_id; + /* next request id or next expected event id */ + uint16_t evt_next_id; + union { + struct { + struct xen_displif_front_ring ring; + struct completion completion; + /* latest response status */ + int resp_status; + } req; + struct { + struct xendispl_event_page *page; + } evt; + } u; +}; + +struct xen_drm_front_evtchnl_pair { + struct xen_drm_front_evtchnl req; + struct xen_drm_front_evtchnl evt; +}; + +int xen_drm_front_evtchnl_create_all(struct xen_drm_front_info *front_info); + +int xen_drm_front_evtchnl_publish_all(struct xen_drm_front_info *front_info); + +void xen_drm_front_evtchnl_flush(struct xen_drm_front_evtchnl *evtchnl); + +void xen_drm_front_evtchnl_set_state(struct xen_drm_front_info *front_info, + enum xen_drm_front_evtchnl_state state); + +void xen_drm_front_evtchnl_free_all(struct xen_drm_front_info *front_info); + +#endif /* __XEN_DRM_FRONT_EVTCHNL_H_ */