[PATCH 24/28] thunderbolt: Add support for DMA tunnels

From: Mika Westerberg
Date: Tue Jan 29 2019 - 10:02:44 EST

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In addition to PCIe and Display Port tunnels it is also possible to
create tunnels that forward DMA traffic from the host interface adapter
(NHI) to a NULL port that is connected to another domain through a
Thunderbolt cable. These tunnels can be used to carry software messages
such as networking packets.

To support this we introduce another tunnel type (TB_TUNNEL_DMA) that
supports paths from NHI to NULL port and back.

Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
---
drivers/thunderbolt/path.c | 20 ++++++--
drivers/thunderbolt/switch.c | 22 ++++++++
drivers/thunderbolt/tb.h | 2 +
drivers/thunderbolt/tb_regs.h | 3 ++
drivers/thunderbolt/tunnel.c | 94 ++++++++++++++++++++++++++++++++++-
drivers/thunderbolt/tunnel.h | 10 ++++
6 files changed, 147 insertions(+), 4 deletions(-)

diff --git a/drivers/thunderbolt/path.c b/drivers/thunderbolt/path.c
index ada60d4aa99b..afdb667fcc0d 100644
--- a/drivers/thunderbolt/path.c
+++ b/drivers/thunderbolt/path.c
@@ -284,7 +284,8 @@ static void __tb_path_deallocate_nfc(struct tb_path *path, int first_hop)
}
}

-static int __tb_path_deactivate_hop(struct tb_port *port, int hop_index)
+static int __tb_path_deactivate_hop(struct tb_port *port, int hop_index,
+ bool clear_fc)
{
struct tb_regs_hop hop;
ktime_t timeout;
@@ -311,8 +312,20 @@ static int __tb_path_deactivate_hop(struct tb_port *port, int hop_index)
if (ret)
return ret;

- if (!hop.pending)
+ if (!hop.pending) {
+ if (clear_fc) {
+ /* Clear flow control */
+ hop.ingress_fc = 0;
+ hop.egress_fc = 0;
+ hop.ingress_shared_buffer = 0;
+ hop.egress_shared_buffer = 0;
+
+ return tb_port_write(port, &hop, TB_CFG_HOPS,
+ 2 * hop_index, 2);
+ }
+
return 0;
+ }

usleep_range(10, 20);
} while (ktime_before(ktime_get(), timeout));
@@ -326,7 +339,8 @@ static void __tb_path_deactivate_hops(struct tb_path *path, int first_hop)

for (i = first_hop; i < path->path_length; i++) {
res = __tb_path_deactivate_hop(path->hops[i].in_port,
- path->hops[i].in_hop_index);
+ path->hops[i].in_hop_index,
+ path->clear_fc);
if (res)
tb_port_warn(path->hops[i].in_port,
"hop deactivation failed for hop %d, index %d\n",
diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index 13dceddcfa48..bcf8b447facb 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -562,6 +562,28 @@ int tb_port_add_nfc_credits(struct tb_port *port, int credits)
TB_CFG_PORT, 4, 1);
}

+/**
+ * tb_port_set_initial_credits() - Set initial port link credits allocated
+ * @port: Port to set the initial credits
+ * @credits: Number of credits to to allocate
+ *
+ * Set initial credits value to be used for ingress shared buffering.
+ */
+int tb_port_set_initial_credits(struct tb_port *port, u32 credits)
+{
+ u32 data;
+ int ret;
+
+ ret = tb_port_read(port, &data, TB_CFG_PORT, 5, 1);
+ if (ret)
+ return ret;
+
+ data &= ~TB_PORT_LCA_MASK;
+ data |= (credits << TB_PORT_LCA_SHIFT) & TB_PORT_LCA_MASK;
+
+ return tb_port_write(port, &data, TB_CFG_PORT, 5, 1);
+}
+
/**
* tb_port_clear_counter() - clear a counter in TB_CFG_COUNTER
*
diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index a85b92a6936b..278b33581d68 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -199,6 +199,7 @@ struct tb_path {
int weight:4;
bool drop_packages;
bool activated;
+ bool clear_fc;
struct tb_path_hop *hops;
int path_length; /* number of hops */
};
@@ -466,6 +467,7 @@ static inline struct tb_switch *tb_to_switch(struct device *dev)

int tb_wait_for_port(struct tb_port *port, bool wait_if_unplugged);
int tb_port_add_nfc_credits(struct tb_port *port, int credits);
+int tb_port_set_initial_credits(struct tb_port *port, u32 credits);
int tb_port_clear_counter(struct tb_port *port, int counter);
int tb_port_alloc_in_hopid(struct tb_port *port, int hopid, int max_hopid);
void tb_port_release_in_hopid(struct tb_port *port, int hopid);
diff --git a/drivers/thunderbolt/tb_regs.h b/drivers/thunderbolt/tb_regs.h
index 420d2a623f31..4591c8b1d546 100644
--- a/drivers/thunderbolt/tb_regs.h
+++ b/drivers/thunderbolt/tb_regs.h
@@ -215,6 +215,9 @@ struct tb_regs_port_header {
#define TB_PORT_NFC_CREDITS_MASK GENMASK(19, 0)
#define TB_PORT_MAX_CREDITS_SHIFT 20
#define TB_PORT_MAX_CREDITS_MASK GENMASK(26, 20)
+/* DWORD 5 */
+#define TB_PORT_LCA_SHIFT 22
+#define TB_PORT_LCA_MASK GENMASK(28, 22)

/* Display Port adapter registers */

diff --git a/drivers/thunderbolt/tunnel.c b/drivers/thunderbolt/tunnel.c
index 5dd648912032..fad18e84d475 100644
--- a/drivers/thunderbolt/tunnel.c
+++ b/drivers/thunderbolt/tunnel.c
@@ -26,7 +26,10 @@
#define TB_DP_AUX_PATH_OUT 1
#define TB_DP_AUX_PATH_IN 2

-static const char * const tb_tunnel_names[] = { "PCI", "DP" };
+#define TB_DMA_PATH_OUT 0
+#define TB_DMA_PATH_IN 1
+
+static const char * const tb_tunnel_names[] = { "PCI", "DP", "DMA" };

#define __TB_TUNNEL_PRINT(level, tunnel, fmt, arg...) \
do { \
@@ -461,6 +464,95 @@ struct tb_tunnel *tb_tunnel_alloc_dp(struct tb *tb, struct tb_port *in,
return NULL;
}

+static u32 tb_dma_credits(struct tb_port *nhi)
+{
+ u32 max_credits;
+
+ max_credits = nhi->config.nfc_credits & TB_PORT_MAX_CREDITS_MASK;
+ max_credits >>= TB_PORT_MAX_CREDITS_SHIFT;
+
+ return min(max_credits, 13U);
+}
+
+static int tb_dma_activate(struct tb_tunnel *tunnel, bool active)
+{
+ struct tb_port *nhi = tunnel->src_port;
+ u32 credits;
+
+ credits = active ? tb_dma_credits(nhi) : 0;
+ return tb_port_set_initial_credits(nhi, credits);
+}
+
+static void tb_dma_init_path(struct tb_path *path, unsigned int isb,
+ unsigned int efc, u32 credits)
+{
+ int i;
+
+ path->egress_fc_enable = efc;
+ path->ingress_fc_enable = TB_PATH_ALL;
+ path->egress_shared_buffer = TB_PATH_NONE;
+ path->ingress_shared_buffer = isb;
+ path->priority = 5;
+ path->weight = 1;
+ path->clear_fc = true;
+
+ for (i = 0; i < path->path_length; i++)
+ path->hops[i].initial_credits = credits;
+}
+
+/**
+ * tb_tunnel_alloc_dma() - allocate a DMA tunnel
+ * @tb: Pointer to the domain structure
+ * @nhi: Host controller port
+ * @dst: Destination null port which the other domain is connected to
+ * @transmit_ring: NHI ring number used to send packets towards the
+ * other domain
+ * @transmit_path: HopID used for transmitting packets
+ * @receive_ring: NHI ring number used to receive packets from the
+ * other domain
+ * @reveive_path: HopID used for receiving packets
+ *
+ * Return: Returns a tb_tunnel on success or NULL on failure.
+ */
+struct tb_tunnel *tb_tunnel_alloc_dma(struct tb *tb, struct tb_port *nhi,
+ struct tb_port *dst, int transmit_ring,
+ int transmit_path, int receive_ring,
+ int receive_path)
+{
+ struct tb_tunnel *tunnel;
+ struct tb_path *path;
+ u32 credits;
+
+ tunnel = tb_tunnel_alloc(tb, 2, TB_TUNNEL_DMA);
+ if (!tunnel)
+ return NULL;
+
+ tunnel->activate = tb_dma_activate;
+ tunnel->src_port = nhi;
+ tunnel->dst_port = dst;
+
+ credits = tb_dma_credits(nhi);
+
+ path = tb_path_alloc(tb, dst, nhi, receive_path, receive_ring, 0);
+ if (!path) {
+ tb_tunnel_free(tunnel);
+ return NULL;
+ }
+ tb_dma_init_path(path, TB_PATH_NONE, TB_PATH_SOURCE | TB_PATH_INTERNAL,
+ credits);
+ tunnel->paths[TB_DMA_PATH_IN] = path;
+
+ path = tb_path_alloc(tb, nhi, dst, transmit_ring, transmit_path, 0);
+ if (!path) {
+ tb_tunnel_free(tunnel);
+ return NULL;
+ }
+ tb_dma_init_path(path, TB_PATH_SOURCE, TB_PATH_ALL, credits);
+ tunnel->paths[TB_DMA_PATH_OUT] = path;
+
+ return tunnel;
+}
+
/**
* tb_tunnel_free() - free a tunnel
* @tunnel: Tunnel to be freed
diff --git a/drivers/thunderbolt/tunnel.h b/drivers/thunderbolt/tunnel.h
index 07583f8247c1..fa51217e5925 100644
--- a/drivers/thunderbolt/tunnel.h
+++ b/drivers/thunderbolt/tunnel.h
@@ -14,6 +14,7 @@
enum tb_tunnel_type {
TB_TUNNEL_PCI,
TB_TUNNEL_DP,
+ TB_TUNNEL_DMA,
};

/**
@@ -44,6 +45,10 @@ struct tb_tunnel *tb_tunnel_alloc_pci(struct tb *tb, struct tb_port *up,
struct tb_tunnel *tb_tunnel_discover_dp(struct tb *tb, struct tb_port *in);
struct tb_tunnel *tb_tunnel_alloc_dp(struct tb *tb, struct tb_port *in,
struct tb_port *out);
+struct tb_tunnel *tb_tunnel_alloc_dma(struct tb *tb, struct tb_port *nhi,
+ struct tb_port *dst, int transmit_ring,
+ int transmit_path, int receive_ring,
+ int receive_path);

void tb_tunnel_free(struct tb_tunnel *tunnel);
int tb_tunnel_activate(struct tb_tunnel *tunnel);
@@ -61,5 +66,10 @@ static inline bool tb_tunnel_is_dp(const struct tb_tunnel *tunnel)
return tunnel->type == TB_TUNNEL_DP;
}

+static inline bool tb_tunnel_is_dma(const struct tb_tunnel *tunnel)
+{
+ return tunnel->type == TB_TUNNEL_DMA;
+}
+
#endif

--
2.20.1

Next message: Mika Westerberg: "[PATCH 08/28] thunderbolt: Properly disable path"
Previous message: Mika Westerberg: "[PATCH 11/28] thunderbolt: Generalize tunnel creation functionality"
In reply to: Mika Westerberg: "[PATCH 11/28] thunderbolt: Generalize tunnel creation functionality"
Next in thread: Mika Westerberg: "[PATCH 08/28] thunderbolt: Properly disable path"
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