There are some NTB hardware, which can combine more than just two domains
over NTB. For instance, some IDT PCIe-switches can have NTB-functions
activated on more than two-ports. The different domains are distinguished
by ports they are connected to. So the new port-related methods are added to
the NTB API:
 ntb_port_number() - return local port
 ntb_peer_port_count() - return number of peers local port can connect to
 ntb_peer_port_number(pdix) - return port number by it index
 ntb_peer_port_idx(port) - return port index by it number

Current test-drivers aren't changed much. They still support two-ports devices
for the time being while multi-ports hardware drivers aren't added.

Signed-off-by: Serge Semin <fancer.lan...@gmail.com>

---
 drivers/ntb/hw/amd/ntb_hw_amd.c     | 47 ++++++++++++++++++++++++
 drivers/ntb/hw/amd/ntb_hw_amd.h     |  9 +++++
 drivers/ntb/hw/intel/ntb_hw_intel.c | 52 ++++++++++++++++++++++++++-
 drivers/ntb/hw/intel/ntb_hw_intel.h |  9 +++++
 drivers/ntb/ntb_transport.c         |  6 ++++
 drivers/ntb/test/ntb_perf.c         |  4 +++
 drivers/ntb/test/ntb_pingpong.c     |  6 ++++
 drivers/ntb/test/ntb_tool.c         |  5 +++
 include/linux/ntb.h                 | 71 +++++++++++++++++++++++++++++++++++++
 9 files changed, 208 insertions(+), 1 deletion(-)

diff --git a/drivers/ntb/hw/amd/ntb_hw_amd.c b/drivers/ntb/hw/amd/ntb_hw_amd.c
index 6704327..0b767ef 100644
--- a/drivers/ntb/hw/amd/ntb_hw_amd.c
+++ b/drivers/ntb/hw/amd/ntb_hw_amd.c
@@ -71,6 +71,49 @@ MODULE_AUTHOR("AMD Inc.");
 static const struct file_operations amd_ntb_debugfs_info;
 static struct dentry *debugfs_dir;
 
+static int amd_ntb_port_number(struct ntb_dev *ntb)
+{
+       switch (ntb->topo) {
+       case NTB_TOPO_PRI:
+       case NTB_TOPO_B2B_USD:
+               return NTB_PORT_PRI_USD;
+       case NTB_TOPO_SEC:
+       case NTB_TOPO_B2B_DSD:
+               return NTB_PORT_SEC_DSD;
+       default:
+               break;
+       }
+
+       return -EINVAL;
+}
+
+static int amd_ntb_peer_port_count(struct ntb_dev *ntb)
+{
+       return NTB_PEER_CNT;
+}
+
+static int amd_ntb_peer_port_number(struct ntb_dev *ntb, int pidx)
+{
+       int local_port = amd_ntb_port_number(ntb);
+
+       if (pidx > NTB_PIDX_MAX)
+               return -EINVAL;
+
+       return (local_port == NTB_PORT_PRI_USD ?
+               NTB_PORT_SEC_DSD : NTB_PORT_PRI_USD);
+}
+
+static int amd_ntb_peer_port_idx(struct ntb_dev *ntb, int port)
+{
+       int local_port = amd_ntb_port_number(ntb);
+
+       if ((local_port == NTB_PORT_PRI_USD && port != NTB_PORT_SEC_DSD) ||
+           (local_port == NTB_PORT_SEC_DSD && port != NTB_PORT_PRI_USD))
+               return -EINVAL;
+
+       return 0;
+}
+
 static int amd_link_is_up(struct amd_ntb_dev *ndev)
 {
        if (!ndev->peer_sta)
@@ -431,6 +474,10 @@ static int amd_ntb_peer_spad_write(struct ntb_dev *ntb,
 }
 
 static const struct ntb_dev_ops amd_ntb_ops = {
+       .port_number            = amd_ntb_port_number,
+       .peer_port_count        = amd_ntb_peer_port_count,
+       .peer_port_number       = amd_ntb_peer_port_number,
+       .peer_port_idx          = amd_ntb_peer_port_idx,
        .link_is_up             = amd_ntb_link_is_up,
        .link_enable            = amd_ntb_link_enable,
        .link_disable           = amd_ntb_link_disable,
diff --git a/drivers/ntb/hw/amd/ntb_hw_amd.h b/drivers/ntb/hw/amd/ntb_hw_amd.h
index 2eac3cd..1aeb08f 100644
--- a/drivers/ntb/hw/amd/ntb_hw_amd.h
+++ b/drivers/ntb/hw/amd/ntb_hw_amd.h
@@ -62,6 +62,10 @@
 #define NTB_LNK_STA_SPEED(x)   (((x) & NTB_LNK_STA_SPEED_MASK) >> 16)
 #define NTB_LNK_STA_WIDTH(x)   (((x) & NTB_LNK_STA_WIDTH_MASK) >> 20)
 
+/* port related constants */
+#define NTB_PEER_CNT                   (1)
+#define NTB_PIDX_MAX                   (0)
+
 #ifndef read64
 #ifdef readq
 #define read64 readq
@@ -91,6 +95,11 @@ static inline void _write64(u64 val, void __iomem *mmio)
 #endif
 #endif
 
+enum amd_ntb_port {
+       NTB_PORT_PRI_USD,
+       NTB_PORT_SEC_DSD
+};
+
 enum {
        /* AMD NTB Capability */
        AMD_MW_CNT              = 3,
diff --git a/drivers/ntb/hw/intel/ntb_hw_intel.c 
b/drivers/ntb/hw/intel/ntb_hw_intel.c
index 68d9908..7e44dc3 100644
--- a/drivers/ntb/hw/intel/ntb_hw_intel.c
+++ b/drivers/ntb/hw/intel/ntb_hw_intel.c
@@ -1035,6 +1035,49 @@ static void ndev_deinit_debugfs(struct intel_ntb_dev 
*ndev)
        debugfs_remove_recursive(ndev->debugfs_dir);
 }
 
+static int intel_ntb_port_number(struct ntb_dev *ntb)
+{
+       switch (ntb->topo) {
+       case NTB_TOPO_PRI:
+       case NTB_TOPO_B2B_USD:
+               return NTB_PORT_PRI_USD;
+       case NTB_TOPO_SEC:
+       case NTB_TOPO_B2B_DSD:
+               return NTB_PORT_SEC_DSD;
+       default:
+               break;
+       }
+
+       return -EINVAL;
+}
+
+static int intel_ntb_peer_port_count(struct ntb_dev *ntb)
+{
+       return NTB_PEER_CNT;
+}
+
+static int intel_ntb_peer_port_number(struct ntb_dev *ntb, int pidx)
+{
+       int local_port = intel_ntb_port_number(ntb);
+
+       if (pidx > NTB_PIDX_MAX)
+               return -EINVAL;
+
+       return (local_port == NTB_PORT_PRI_USD ?
+               NTB_PORT_SEC_DSD : NTB_PORT_PRI_USD);
+}
+
+static int intel_ntb_peer_port_idx(struct ntb_dev *ntb, int port)
+{
+       int local_port = intel_ntb_port_number(ntb);
+
+       if ((local_port == NTB_PORT_PRI_USD && port != NTB_PORT_SEC_DSD) ||
+           (local_port == NTB_PORT_SEC_DSD && port != NTB_PORT_PRI_USD))
+               return -EINVAL;
+
+       return 0;
+}
+
 static int intel_ntb_link_is_up(struct ntb_dev *ntb,
                                enum ntb_speed *speed,
                                enum ntb_width *width)
@@ -1775,7 +1818,6 @@ static int skx_init_ntb(struct intel_ntb_dev *ndev)
 {
        int rc;
 
-
        ndev->mw_count = XEON_MW_COUNT;
        ndev->spad_count = SKX_SPAD_COUNT;
        ndev->db_count = SKX_DB_COUNT;
@@ -2883,6 +2925,10 @@ static const struct intel_ntb_xlat_reg skx_sec_xlat = {
 
 /* operations for primary side of local ntb */
 static const struct ntb_dev_ops intel_ntb_ops = {
+       .port_number            = intel_ntb_port_number,
+       .peer_port_count        = intel_ntb_peer_port_count,
+       .peer_port_number       = intel_ntb_peer_port_number,
+       .peer_port_idx          = intel_ntb_peer_port_idx,
        .link_is_up             = intel_ntb_link_is_up,
        .link_enable            = intel_ntb_link_enable,
        .link_disable           = intel_ntb_link_disable,
@@ -2909,6 +2955,10 @@ static const struct ntb_dev_ops intel_ntb_ops = {
 };
 
 static const struct ntb_dev_ops intel_ntb3_ops = {
+       .port_number            = intel_ntb_port_number,
+       .peer_port_count        = intel_ntb_peer_port_count,
+       .peer_port_number       = intel_ntb_peer_port_number,
+       .peer_port_idx          = intel_ntb_peer_port_idx,
        .link_is_up             = intel_ntb_link_is_up,
        .link_enable            = intel_ntb3_link_enable,
        .link_disable           = intel_ntb_link_disable,
diff --git a/drivers/ntb/hw/intel/ntb_hw_intel.h 
b/drivers/ntb/hw/intel/ntb_hw_intel.h
index 6e8c182..f12c960 100644
--- a/drivers/ntb/hw/intel/ntb_hw_intel.h
+++ b/drivers/ntb/hw/intel/ntb_hw_intel.h
@@ -295,6 +295,15 @@
 #define NTB_BAR_MASK_64                        ~(0xfull)
 #define NTB_BAR_MASK_32                        ~(0xfu)
 
+/* port related constants */
+#define NTB_PEER_CNT                   (1)
+#define NTB_PIDX_MAX                   (0)
+
+enum intel_ntb_port {
+       NTB_PORT_PRI_USD,
+       NTB_PORT_SEC_DSD
+};
+
 struct intel_ntb_dev;
 
 struct intel_ntb_reg {
diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
index 4eb8adb..37d428d 100644
--- a/drivers/ntb/ntb_transport.c
+++ b/drivers/ntb/ntb_transport.c
@@ -94,6 +94,9 @@ MODULE_PARM_DESC(use_dma, "Use DMA engine to perform large 
data copy");
 
 static struct dentry *nt_debugfs_dir;
 
+/* Only two-ports NTB devices are supported */
+#define PIDX           0
+
 struct ntb_queue_entry {
        /* ntb_queue list reference */
        struct list_head entry;
@@ -1083,6 +1086,9 @@ static int ntb_transport_probe(struct ntb_client *self, 
struct ntb_dev *ndev)
                dev_dbg(&ndev->dev,
                        "scratchpad is unsafe, proceed anyway...\n");
 
+       if (ntb_peer_port_count(ndev) != 1)
+               dev_warn(&ndev->dev, "Multi-port NTB devices unsupported\n");
+
        node = dev_to_node(&ndev->dev);
 
        nt = kzalloc_node(sizeof(*nt), GFP_KERNEL, node);
diff --git a/drivers/ntb/test/ntb_perf.c b/drivers/ntb/test/ntb_perf.c
index e75d4fd..481827a 100644
--- a/drivers/ntb/test/ntb_perf.c
+++ b/drivers/ntb/test/ntb_perf.c
@@ -76,6 +76,7 @@
 #define DMA_RETRIES            20
 #define SZ_4G                  (1ULL << 32)
 #define MAX_SEG_ORDER          20 /* no larger than 1M for kmalloc buffer */
+#define PIDX                   0
 
 MODULE_LICENSE(DRIVER_LICENSE);
 MODULE_VERSION(DRIVER_VERSION);
@@ -764,6 +765,9 @@ static int perf_probe(struct ntb_client *client, struct 
ntb_dev *ntb)
                return -EIO;
        }
 
+       if (ntb_peer_port_count(ntb) != 1)
+               dev_warn(&ntb->dev, "Multi-port NTB devices unsupported\n");
+
        node = dev_to_node(&pdev->dev);
 
        perf = kzalloc_node(sizeof(*perf), GFP_KERNEL, node);
diff --git a/drivers/ntb/test/ntb_pingpong.c b/drivers/ntb/test/ntb_pingpong.c
index 4358611..6dd7582 100644
--- a/drivers/ntb/test/ntb_pingpong.c
+++ b/drivers/ntb/test/ntb_pingpong.c
@@ -90,6 +90,9 @@ static unsigned long db_init = 0x7;
 module_param(db_init, ulong, 0644);
 MODULE_PARM_DESC(db_init, "Initial doorbell bits to ring on the peer");
 
+/* Only two-ports NTB devices are supported */
+#define PIDX           0
+
 struct pp_ctx {
        struct ntb_dev                  *ntb;
        u64                             db_bits;
@@ -230,6 +233,9 @@ static int pp_probe(struct ntb_client *client,
                }
        }
 
+       if (ntb_peer_port_count(ntb) != 1)
+               dev_warn(&ntb->dev, "multi-port NTB is unsupported\n");
+
        pp = kmalloc(sizeof(*pp), GFP_KERNEL);
        if (!pp) {
                rc = -ENOMEM;
diff --git a/drivers/ntb/test/ntb_tool.c b/drivers/ntb/test/ntb_tool.c
index 61bf2ef..85b6417 100644
--- a/drivers/ntb/test/ntb_tool.c
+++ b/drivers/ntb/test/ntb_tool.c
@@ -120,6 +120,8 @@ MODULE_AUTHOR(DRIVER_AUTHOR);
 MODULE_DESCRIPTION(DRIVER_DESCRIPTION);
 
 #define MAX_MWS 16
+/* Only two-ports devices are supported */
+#define PIDX   0
 
 static struct dentry *tool_dbgfs;
 
@@ -919,6 +921,9 @@ static int tool_probe(struct ntb_client *self, struct 
ntb_dev *ntb)
        if (ntb_spad_is_unsafe(ntb))
                dev_dbg(&ntb->dev, "scratchpad is unsafe\n");
 
+       if (ntb_peer_port_count(ntb) != 1)
+               dev_warn(&ntb->dev, "multi-port NTB is unsupported\n");
+
        tc = kzalloc(sizeof(*tc), GFP_KERNEL);
        if (!tc) {
                rc = -ENOMEM;
diff --git a/include/linux/ntb.h b/include/linux/ntb.h
index 5d1f260..3216689 100644
--- a/include/linux/ntb.h
+++ b/include/linux/ntb.h
@@ -179,6 +179,10 @@ static inline int ntb_ctx_ops_is_valid(const struct 
ntb_ctx_ops *ops)
 
 /**
  * struct ntb_ctx_ops - ntb device operations
+ * @port_number:       See ntb_port_number().
+ * @peer_port_count:   See ntb_peer_port_count().
+ * @peer_port_number:  See ntb_peer_port_number().
+ * @peer_port_idx:     See ntb_peer_port_idx().
  * @link_is_up:                See ntb_link_is_up().
  * @link_enable:       See ntb_link_enable().
  * @link_disable:      See ntb_link_disable().
@@ -212,6 +216,11 @@ static inline int ntb_ctx_ops_is_valid(const struct 
ntb_ctx_ops *ops)
  * @peer_spad_write:   See ntb_peer_spad_write().
  */
 struct ntb_dev_ops {
+       int (*port_number)(struct ntb_dev *ntb);
+       int (*peer_port_count)(struct ntb_dev *ntb);
+       int (*peer_port_number)(struct ntb_dev *ntb, int pidx);
+       int (*peer_port_idx)(struct ntb_dev *ntb, int port);
+
        int (*link_is_up)(struct ntb_dev *ntb,
                          enum ntb_speed *speed, enum ntb_width *width);
        int (*link_enable)(struct ntb_dev *ntb,
@@ -265,6 +274,10 @@ static inline int ntb_dev_ops_is_valid(const struct 
ntb_dev_ops *ops)
 {
        /* commented callbacks are not required: */
        return
+               ops->port_number                        &&
+               ops->peer_port_count                    &&
+               ops->peer_port_number                   &&
+               ops->peer_port_idx                      &&
                ops->link_is_up                         &&
                ops->link_enable                        &&
                ops->link_disable                       &&
@@ -442,6 +455,64 @@ void ntb_link_event(struct ntb_dev *ntb);
 void ntb_db_event(struct ntb_dev *ntb, int vector);
 
 /**
+ * ntb_port_number() - get the local port number
+ * @ntb:       NTB device context.
+ *
+ * Hardware must support at least simple two-ports ntb connection
+ *
+ * Return: the local port number
+ */
+static inline int ntb_port_number(struct ntb_dev *ntb)
+{
+       return ntb->ops->port_number(ntb);
+}
+
+/**
+ * ntb_peer_port_count() - get the number of peer device ports
+ * @ntb:       NTB device context.
+ *
+ * Hardware may support an access to memory of several remote domains
+ * over multi-port NTB devices. This method returns the number of peers,
+ * local device can have shared memory with.
+ *
+ * Return: the number of peer ports
+ */
+static inline int ntb_peer_port_count(struct ntb_dev *ntb)
+{
+       return ntb->ops->peer_port_count(ntb);
+}
+
+/**
+ * ntb_peer_port_number() - get the peer port by given index
+ * @ntb:       NTB device context.
+ * @pidx:      Peer port index.
+ *
+ * Peer ports are continuously enumerated by NTB API logic, so this methods
+ * lets to retrieve port real number by its index.
+ *
+ * Return: the peer device port or negative value indicating an error
+ */
+static inline int ntb_peer_port_number(struct ntb_dev *ntb, int pidx)
+{
+       return ntb->ops->peer_port_number(ntb, pidx);
+}
+
+/**
+ * ntb_peer_port_idx() - get the peer device port index by given port number
+ * @ntb:       NTB device context.
+ * @port:      Peer port number.
+ *
+ * Inverse operation of ntb_peer_port_number(), so one can get port index
+ * by specified port number.
+ *
+ * Return: the peer port index or negative value indicating an error
+ */
+static inline int ntb_peer_port_idx(struct ntb_dev *ntb, int port)
+{
+       return ntb->ops->peer_port_idx(ntb, port);
+}
+
+/**
  * ntb_link_is_up() - get the current ntb link state
  * @ntb:       NTB device context.
  * @speed:     OUT - The link speed expressed as PCIe generation number.
-- 
2.6.6

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