firmware: arm_ffa: Implement the FFA_NOTIFICATION_GET interface

The framework provides an interface to the receiver to determine the
identity of the notification. A receiver endpoint must use the
FFA_NOTIFICATION_GET interface to retrieve its pending notifications
and handle them.

Add the support for FFA_NOTIFICATION_GET to allow the caller(receiver)
to fetch its pending notifications from other partitions in the system.

Link: https://lore.kernel.org/r/20231005-ffa_v1-1_notif-v4-6-cddd3237809c@arm.comSigned-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_ffa/driver.c

@@ -593,6 +593,14 @@ static int ffa_notification_bitmap_destroy(void)
 		((u32)(FIELD_GET(NOTIFICATION_HIGH_MASK, (x))))
 #define NOTIFICATION_BITMAP_LOW(x)	\
 		((u32)(FIELD_GET(NOTIFICATION_LOW_MASK, (x))))
+#define PACK_NOTIFICATION_BITMAP(low, high)	\
+	(FIELD_PREP(NOTIFICATION_LOW_MASK, (low)) | \
+	 FIELD_PREP(NOTIFICATION_HIGH_MASK, (high)))
+
+#define RECEIVER_VCPU_MASK		GENMASK(31, 16)
+#define PACK_NOTIFICATION_GET_RECEIVER_INFO(vcpu_r, r) \
+	(FIELD_PREP(RECEIVER_VCPU_MASK, (vcpu_r)) | \
+	 FIELD_PREP(RECEIVER_ID_MASK, (r)))
 
 static int ffa_notification_bind_common(u16 dst_id, u64 bitmap,
 					u32 flags, bool is_bind)
@@ -636,6 +644,35 @@ int ffa_notification_set(u16 src_id, u16 dst_id, u32 flags, u64 bitmap)
 	return 0;
 }
 
+struct ffa_notify_bitmaps {
+	u64 sp_map;
+	u64 vm_map;
+	u64 arch_map;
+};
+
+static int ffa_notification_get(u32 flags, struct ffa_notify_bitmaps *notify)
+{
+	ffa_value_t ret;
+	u16 src_id = drv_info->vm_id;
+	u16 cpu_id = smp_processor_id();
+	u32 rec_vcpu_ids = PACK_NOTIFICATION_GET_RECEIVER_INFO(cpu_id, src_id);
+
+	invoke_ffa_fn((ffa_value_t){
+		  .a0 = FFA_NOTIFICATION_GET, .a1 = rec_vcpu_ids, .a2 = flags,
+		  }, &ret);
+
+	if (ret.a0 == FFA_ERROR)
+		return ffa_to_linux_errno((int)ret.a2);
+	else if (ret.a0 != FFA_SUCCESS)
+		return -EINVAL; /* Something else went wrong. */
+
+	notify->sp_map = PACK_NOTIFICATION_BITMAP(ret.a2, ret.a3);
+	notify->vm_map = PACK_NOTIFICATION_BITMAP(ret.a4, ret.a5);
+	notify->arch_map = PACK_NOTIFICATION_BITMAP(ret.a6, ret.a7);
+
+	return 0;
+}
+
 static int ffa_run(struct ffa_device *dev, u16 vcpu)
 {
 	ffa_value_t ret;