thunderbolt: Read router preferred credit allocation information

USB4 routers must expose their preferred credit (buffer) allocation
information through router operation. This information tells the
connection manager how the router prefers its buffers to be allocated to
get the expected bandwidth for the supported protocols.

Read this information and store it as part of struct tb_switch for each
USB4 router.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

1 files changed, 43 insertions, 8 deletions

diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index d5420eefe25d..ac6cb304c49f 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -488,17 +488,21 @@ static const char *tb_port_type(const struct tb_regs_port_header *port)
 	}
 }
 
-static void tb_dump_port(struct tb *tb, struct tb_regs_port_header *port)
+static void tb_dump_port(struct tb *tb, const struct tb_port *port)
 {
+	const struct tb_regs_port_header *regs = &port->config;
+
 	tb_dbg(tb,
 	       " Port %d: %x:%x (Revision: %d, TB Version: %d, Type: %s (%#x))\n",
-	       port->port_number, port->vendor_id, port->device_id,
-	       port->revision, port->thunderbolt_version, tb_port_type(port),
-	       port->type);
+	       regs->port_number, regs->vendor_id, regs->device_id,
+	       regs->revision, regs->thunderbolt_version, tb_port_type(regs),
+	       regs->type);
 	tb_dbg(tb, "  Max hop id (in/out): %d/%d\n",
-	       port->max_in_hop_id, port->max_out_hop_id);
-	tb_dbg(tb, "  Max counters: %d\n", port->max_counters);
-	tb_dbg(tb, "  NFC Credits: %#x\n", port->nfc_credits);
+	       regs->max_in_hop_id, regs->max_out_hop_id);
+	tb_dbg(tb, "  Max counters: %d\n", regs->max_counters);
+	tb_dbg(tb, "  NFC Credits: %#x\n", regs->nfc_credits);
+	tb_dbg(tb, "  Credits (total/control): %u/%u\n", port->total_credits,
+	       port->ctl_credits);
 }
 
 /**
@@ -738,13 +742,32 @@ static int tb_init_port(struct tb_port *port)
 		cap = tb_port_find_cap(port, TB_PORT_CAP_USB4);
 		if (cap > 0)
 			port->cap_usb4 = cap;
+
+		/*
+		 * USB4 ports the buffers allocated for the control path
+		 * can be read from the path config space. Legacy
+		 * devices we use hard-coded value.
+		 */
+		if (tb_switch_is_usb4(port->sw)) {
+			struct tb_regs_hop hop;
+
+			if (!tb_port_read(port, &hop, TB_CFG_HOPS, 0, 2))
+				port->ctl_credits = hop.initial_credits;
+		}
+		if (!port->ctl_credits)
+			port->ctl_credits = 2;
+
 	} else if (port->port != 0) {
 		cap = tb_port_find_cap(port, TB_PORT_CAP_ADAP);
 		if (cap > 0)
 			port->cap_adap = cap;
 	}
 
-	tb_dump_port(port->sw->tb, &port->config);
+	port->total_credits =
+		(port->config.nfc_credits & ADP_CS_4_TOTAL_BUFFERS_MASK) >>
+		ADP_CS_4_TOTAL_BUFFERS_SHIFT;
+
+	tb_dump_port(port->sw->tb, port);
 
 	INIT_LIST_HEAD(&port->list);
 	return 0;
@@ -2575,6 +2598,16 @@ void tb_switch_unconfigure_link(struct tb_switch *sw)
 		tb_lc_unconfigure_port(down);
 }
 
+static void tb_switch_credits_init(struct tb_switch *sw)
+{
+	if (tb_switch_is_icm(sw))
+		return;
+	if (!tb_switch_is_usb4(sw))
+		return;
+	if (usb4_switch_credits_init(sw))
+		tb_sw_info(sw, "failed to determine preferred buffer allocation, using defaults\n");
+}
+
 /**
  * tb_switch_add() - Add a switch to the domain
  * @sw: Switch to add
@@ -2605,6 +2638,8 @@ int tb_switch_add(struct tb_switch *sw)
 	}
 
 	if (!sw->safe_mode) {
+		tb_switch_credits_init(sw);
+
 		/* read drom */
 		ret = tb_drom_read(sw);
 		if (ret) {