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, 155 insertions, 0 deletions

diff --git a/drivers/thunderbolt/usb4.c b/drivers/thunderbolt/usb4.c
index b56af7b0a093..edab8ea63c0b 100644
--- a/drivers/thunderbolt/usb4.c
+++ b/drivers/thunderbolt/usb4.c
@@ -36,6 +36,20 @@ enum usb4_sb_target {
 
 #define USB4_NVM_SECTOR_SIZE_MASK	GENMASK(23, 0)
 
+#define USB4_BA_LENGTH_MASK		GENMASK(7, 0)
+#define USB4_BA_INDEX_MASK		GENMASK(15, 0)
+
+enum usb4_ba_index {
+	USB4_BA_MAX_USB3 = 0x1,
+	USB4_BA_MIN_DP_AUX = 0x2,
+	USB4_BA_MIN_DP_MAIN = 0x3,
+	USB4_BA_MAX_PCIE = 0x4,
+	USB4_BA_MAX_HI = 0x5,
+};
+
+#define USB4_BA_VALUE_MASK		GENMASK(31, 16)
+#define USB4_BA_VALUE_SHIFT		16
+
 static int usb4_switch_wait_for_bit(struct tb_switch *sw, u32 offset, u32 bit,
 				    u32 value, int timeout_msec)
 {
@@ -670,6 +684,147 @@ int usb4_switch_nvm_authenticate_status(struct tb_switch *sw, u32 *status)
 }
 
 /**
+ * usb4_switch_credits_init() - Read buffer allocation parameters
+ * @sw: USB4 router
+ *
+ * Reads @sw buffer allocation parameters and initializes @sw buffer
+ * allocation fields accordingly. Specifically @sw->credits_allocation
+ * is set to %true if these parameters can be used in tunneling.
+ *
+ * Returns %0 on success and negative errno otherwise.
+ */
+int usb4_switch_credits_init(struct tb_switch *sw)
+{
+	int max_usb3, min_dp_aux, min_dp_main, max_pcie, max_dma;
+	int ret, length, i, nports;
+	const struct tb_port *port;
+	u32 data[NVM_DATA_DWORDS];
+	u32 metadata = 0;
+	u8 status = 0;
+
+	memset(data, 0, sizeof(data));
+	ret = usb4_switch_op_data(sw, USB4_SWITCH_OP_BUFFER_ALLOC, &metadata,
+				  &status, NULL, 0, data, ARRAY_SIZE(data));
+	if (ret)
+		return ret;
+	if (status)
+		return -EIO;
+
+	length = metadata & USB4_BA_LENGTH_MASK;
+	if (WARN_ON(length > ARRAY_SIZE(data)))
+		return -EMSGSIZE;
+
+	max_usb3 = -1;
+	min_dp_aux = -1;
+	min_dp_main = -1;
+	max_pcie = -1;
+	max_dma = -1;
+
+	tb_sw_dbg(sw, "credit allocation parameters:\n");
+
+	for (i = 0; i < length; i++) {
+		u16 index, value;
+
+		index = data[i] & USB4_BA_INDEX_MASK;
+		value = (data[i] & USB4_BA_VALUE_MASK) >> USB4_BA_VALUE_SHIFT;
+
+		switch (index) {
+		case USB4_BA_MAX_USB3:
+			tb_sw_dbg(sw, " USB3: %u\n", value);
+			max_usb3 = value;
+			break;
+		case USB4_BA_MIN_DP_AUX:
+			tb_sw_dbg(sw, " DP AUX: %u\n", value);
+			min_dp_aux = value;
+			break;
+		case USB4_BA_MIN_DP_MAIN:
+			tb_sw_dbg(sw, " DP main: %u\n", value);
+			min_dp_main = value;
+			break;
+		case USB4_BA_MAX_PCIE:
+			tb_sw_dbg(sw, " PCIe: %u\n", value);
+			max_pcie = value;
+			break;
+		case USB4_BA_MAX_HI:
+			tb_sw_dbg(sw, " DMA: %u\n", value);
+			max_dma = value;
+			break;
+		default:
+			tb_sw_dbg(sw, " unknown credit allocation index %#x, skipping\n",
+				  index);
+			break;
+		}
+	}
+
+	/*
+	 * Validate the buffer allocation preferences. If we find
+	 * issues, log a warning and fall back using the hard-coded
+	 * values.
+	 */
+
+	/* Host router must report baMaxHI */
+	if (!tb_route(sw) && max_dma < 0) {
+		tb_sw_warn(sw, "host router is missing baMaxHI\n");
+		goto err_invalid;
+	}
+
+	nports = 0;
+	tb_switch_for_each_port(sw, port) {
+		if (tb_port_is_null(port))
+			nports++;
+	}
+
+	/* Must have DP buffer allocation (multiple USB4 ports) */
+	if (nports > 2 && (min_dp_aux < 0 || min_dp_main < 0)) {
+		tb_sw_warn(sw, "multiple USB4 ports require baMinDPaux/baMinDPmain\n");
+		goto err_invalid;
+	}
+
+	tb_switch_for_each_port(sw, port) {
+		if (tb_port_is_dpout(port) && min_dp_main < 0) {
+			tb_sw_warn(sw, "missing baMinDPmain");
+			goto err_invalid;
+		}
+		if ((tb_port_is_dpin(port) || tb_port_is_dpout(port)) &&
+		    min_dp_aux < 0) {
+			tb_sw_warn(sw, "missing baMinDPaux");
+			goto err_invalid;
+		}
+		if ((tb_port_is_usb3_down(port) || tb_port_is_usb3_up(port)) &&
+		    max_usb3 < 0) {
+			tb_sw_warn(sw, "missing baMaxUSB3");
+			goto err_invalid;
+		}
+		if ((tb_port_is_pcie_down(port) || tb_port_is_pcie_up(port)) &&
+		    max_pcie < 0) {
+			tb_sw_warn(sw, "missing baMaxPCIe");
+			goto err_invalid;
+		}
+	}
+
+	/*
+	 * Buffer allocation passed the validation so we can use it in
+	 * path creation.
+	 */
+	sw->credit_allocation = true;
+	if (max_usb3 > 0)
+		sw->max_usb3_credits = max_usb3;
+	if (min_dp_aux > 0)
+		sw->min_dp_aux_credits = min_dp_aux;
+	if (min_dp_main > 0)
+		sw->min_dp_main_credits = min_dp_main;
+	if (max_pcie > 0)
+		sw->max_pcie_credits = max_pcie;
+	if (max_dma > 0)
+		sw->max_dma_credits = max_dma;
+
+	return 0;
+
+err_invalid:
+	return -EINVAL;
+}
+
+/**
  * usb4_switch_query_dp_resource() - Query availability of DP IN resource
  * @sw: USB4 router
  * @in: DP IN adapter