[PATCH v3 3/5] misc: fastrpc: Add DSP PD notification support

[Ekansh Gupta]

Current driver design does not provide any notification regarding
the status of used PD on DSP. Only when user makes a FastRPC
invocation, they get to know if the process has been killed on
DSP. Notifying status of user PD can help users to restart the
DSP PD session.

Co-developed-by: Anandu Krishnan E <quic_anane@xxxxxxxxxxx>
Signed-off-by: Anandu Krishnan E <quic_anane@xxxxxxxxxxx>
Signed-off-by: Ekansh Gupta <quic_ekangupt@xxxxxxxxxxx>
---
Changes in v2:
  - Added Co-developer tag
Changes in v3:
  - Rebase the patch to latest kernel version

 drivers/misc/fastrpc.c      | 145 +++++++++++++++++++++++++++++++++++-
 include/uapi/misc/fastrpc.h |   8 ++
 2 files changed, 152 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 4f8ecfcdf89f..72ed14174363 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -120,6 +120,8 @@
 /* CPU feature information to DSP */
 #define FASTRPC_CPUINFO_DEFAULT (0)
 #define FASTRPC_CPUINFO_EARLY_WAKEUP (1)
+/* Process status notifications from DSP will be sent with this unique context */
+#define FASTRPC_NOTIF_CTX_RESERVED 0xABCDABCD
 
 #define miscdev_to_fdevice(d) container_of(d, struct fastrpc_device, miscdev)
 
@@ -238,6 +240,13 @@ struct fastrpc_invoke_rspv2 {
 	u32 version;		/* version number */
 };
 
+struct dsp_notif_rsp {
+	u64 ctx;		/* response context */
+	u32 type;		/* Notification type */
+	int pid;		/* user process pid */
+	u32 status;		/* userpd status notification */
+};
+
 struct fastrpc_buf_overlap {
 	u64 start;
 	u64 end;
@@ -297,6 +306,27 @@ struct fastrpc_perf {
 	u64 tid;
 };
 
+struct fastrpc_notif_queue {
+	/* Number of pending status notifications in queue */
+	atomic_t notif_queue_count;
+	/* Wait queue to synchronize notifier thread and response */
+	wait_queue_head_t notif_wait_queue;
+	/* IRQ safe spin lock for protecting notif queue */
+	spinlock_t nqlock;
+};
+
+struct fastrpc_internal_notif_rsp {
+	u32 domain;		/* Domain of User PD */
+	u32 session;	/* Session ID of User PD */
+	u32 status;		/* Status of the process */
+};
+
+struct fastrpc_notif_rsp {
+	struct list_head notifn;
+	u32 domain;
+	enum fastrpc_status_flags status;
+};
+
 struct fastrpc_invoke_ctx {
 	int nscalars;
 	int nbufs;
@@ -376,10 +406,13 @@ struct fastrpc_user {
 	struct list_head pending;
 	struct list_head interrupted;
 	struct list_head mmaps;
+	struct list_head notif_queue;
 
 	struct fastrpc_channel_ctx *cctx;
 	struct fastrpc_session_ctx *sctx;
 	struct fastrpc_buf *init_mem;
+	/* Process status notification queue */
+	struct fastrpc_notif_queue proc_state_notif;
 
 	u32 profile;
 	/* Threads poll for specified timeout and fall back to glink wait */
@@ -2085,6 +2118,99 @@ static int fastrpc_invoke(struct fastrpc_user *fl, char __user *argp)
 	return err;
 }
 
+static void fastrpc_queue_pd_status(struct fastrpc_user *fl, int domain, int status)
+{
+	struct fastrpc_notif_rsp *notif_rsp = NULL;
+	unsigned long flags;
+
+	notif_rsp = kzalloc(sizeof(*notif_rsp), GFP_ATOMIC);
+	if (!notif_rsp)
+		return;
+
+	notif_rsp->status = status;
+	notif_rsp->domain = domain;
+
+	spin_lock_irqsave(&fl->proc_state_notif.nqlock, flags);
+	list_add_tail(&notif_rsp->notifn, &fl->notif_queue);
+	atomic_add(1, &fl->proc_state_notif.notif_queue_count);
+	wake_up_interruptible(&fl->proc_state_notif.notif_wait_queue);
+	spin_unlock_irqrestore(&fl->proc_state_notif.nqlock, flags);
+}
+
+static void fastrpc_notif_find_process(int domain, struct fastrpc_channel_ctx *cctx, struct dsp_notif_rsp *notif)
+{
+	bool is_process_found = false;
+	unsigned long irq_flags = 0;
+	struct fastrpc_user *user;
+
+	spin_lock_irqsave(&cctx->lock, irq_flags);
+	list_for_each_entry(user, &cctx->users, user) {
+		if (user->tgid == notif->pid) {
+			is_process_found = true;
+			break;
+		}
+	}
+	spin_unlock_irqrestore(&cctx->lock, irq_flags);
+
+	if (!is_process_found)
+		return;
+	fastrpc_queue_pd_status(user, domain, notif->status);
+}
+
+static int fastrpc_wait_on_notif_queue(
+			struct fastrpc_internal_notif_rsp *notif_rsp,
+			struct fastrpc_user *fl)
+{
+	int err = 0;
+	unsigned long flags;
+	struct fastrpc_notif_rsp *notif, *inotif, *n;
+
+read_notif_status:
+	err = wait_event_interruptible(fl->proc_state_notif.notif_wait_queue,
+				atomic_read(&fl->proc_state_notif.notif_queue_count));
+	if (err) {
+		kfree(notif);
+		return err;
+	}
+
+	spin_lock_irqsave(&fl->proc_state_notif.nqlock, flags);
+	list_for_each_entry_safe(inotif, n, &fl->notif_queue, notifn) {
+		list_del(&inotif->notifn);
+		atomic_sub(1, &fl->proc_state_notif.notif_queue_count);
+		notif = inotif;
+		break;
+	}
+	spin_unlock_irqrestore(&fl->proc_state_notif.nqlock, flags);
+
+	if (notif) {
+		notif_rsp->status = notif->status;
+		notif_rsp->domain = notif->domain;
+	} else {// Go back to wait if ctx is invalid
+		dev_err(fl->sctx->dev, "Invalid status notification response\n");
+		goto read_notif_status;
+	}
+
+	kfree(notif);
+	return err;
+}
+
+static int fastrpc_get_notif_response(
+			struct fastrpc_internal_notif_rsp *notif,
+			void *param, struct fastrpc_user *fl)
+{
+	int err = 0;
+
+	err = fastrpc_wait_on_notif_queue(notif, fl);
+	if (err)
+		return err;
+
+	if (copy_to_user((void __user *)param, notif,
+			sizeof(struct fastrpc_internal_notif_rsp)))
+		return -EFAULT;
+
+	return 0;
+}
+
 static int fastrpc_manage_poll_mode(struct fastrpc_user *fl, u32 enable, u32 timeout)
 {
 	const unsigned int MAX_POLL_TIMEOUT_US = 10000;
@@ -2141,6 +2267,7 @@ static int fastrpc_multimode_invoke(struct fastrpc_user *fl, char __user *argp)
 	struct fastrpc_invoke_args *args = NULL;
 	struct fastrpc_ioctl_multimode_invoke invoke;
 	struct fastrpc_internal_control cp = {0};
+	struct fastrpc_internal_notif_rsp notif;
 	u32 nscalars;
 	u64 *perf_kernel;
 	int err, i;
@@ -2190,6 +2317,10 @@ static int fastrpc_multimode_invoke(struct fastrpc_user *fl, char __user *argp)
 
 		err = fastrpc_internal_control(fl, &cp);
 		break;
+	case FASTRPC_INVOKE_NOTIF:
+		err = fastrpc_get_notif_response(&notif,
+					(void *)invoke.invparam, fl);
+		break;
 	default:
 		err = -ENOTTY;
 		break;
@@ -2944,8 +3075,10 @@ static void fastrpc_rpmsg_remove(struct rpmsg_device *rpdev)
 	/* No invocations past this point */
 	spin_lock_irqsave(&cctx->lock, flags);
 	cctx->rpdev = NULL;
-	list_for_each_entry(user, &cctx->users, user)
+	list_for_each_entry(user, &cctx->users, user) {
+		fastrpc_queue_pd_status(user, cctx->domain_id, FASTRPC_DSP_SSR);
 		fastrpc_notify_users(user);
+	}
 	spin_unlock_irqrestore(&cctx->lock, flags);
 
 	if (cctx->fdevice)
@@ -2996,12 +3129,22 @@ static int fastrpc_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
 	struct fastrpc_channel_ctx *cctx = dev_get_drvdata(&rpdev->dev);
 	struct fastrpc_invoke_rsp *rsp = data;
 	struct fastrpc_invoke_rspv2 *rspv2 = NULL;
+	struct dsp_notif_rsp *notif = (struct dsp_notif_rsp *)data;
 	struct fastrpc_invoke_ctx *ctx;
 	unsigned long flags;
 	unsigned long ctxid;
 	u32 rsp_flags = 0;
 	u32 early_wake_time = 0;
 
+	if (notif->ctx == FASTRPC_NOTIF_CTX_RESERVED) {
+		if (notif->type == STATUS_RESPONSE && len >= sizeof(*notif)) {
+			fastrpc_notif_find_process(cctx->domain_id, cctx, notif);
+			return 0;
+		} else {
+			return -ENOENT;
+		}
+	}
+
 	if (len < sizeof(*rsp))
 		return -EINVAL;
 
diff --git a/include/uapi/misc/fastrpc.h b/include/uapi/misc/fastrpc.h
index 3dfd8e95eda8..1f544a35ee4e 100644
--- a/include/uapi/misc/fastrpc.h
+++ b/include/uapi/misc/fastrpc.h
@@ -192,4 +192,12 @@ enum fastrpc_perfkeys {
 	PERF_KEY_MAX = 10,
 };
 
+enum fastrpc_status_flags {
+	FASTRPC_USERPD_UP			= 0,
+	FASTRPC_USERPD_EXIT			= 1,
+	FASTRPC_USERPD_FORCE_KILL	= 2,
+	FASTRPC_USERPD_EXCEPTION	= 3,
+	FASTRPC_DSP_SSR				= 4,
+};
+
 #endif /* __QCOM_FASTRPC_H__ */
-- 
2.17.1