soc/intel/tgl,mb/google/volteer: Add API for Type-C aux bias pads

TGL boards using the Type-C subsystem for USB Type-C ports without a
retimer attached may require a DC bias on the aux lines for certain
modes to work. This patch adds native coreboot support for programming
the IOM to handle this DC bias via a simple devicetree
setting. Previously a UPD was required to tell the FSP which GPIOs were
used for the pullup and pulldown biases, but the API for this UPD was
effectively undocumented.

BUG=b:174116646
TEST=Verified on volteer2 that a Type-C flash drive is enumerated
succesfully on all ports. Verified all major power flows (boot, reboot,
powerdown and S0ix/suspend) still work as expected.

Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Change-Id: I70e36a41e760f4a435511c147cc5744a77dbccc0
Reviewed-on: https://review.coreboot.org/c/coreboot/+/51649
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

2 files changed, 48 insertions, 2 deletions

diff --git a/src/soc/intel/common/block/include/intelblocks/tcss.h b/src/soc/intel/common/block/include/intelblocks/tcss.h
index 68e279ca2a..29093d1664 100644
--- a/src/soc/intel/common/block/include/intelblocks/tcss.h
+++ b/src/soc/intel/common/block/include/intelblocks/tcss.h
@@ -3,6 +3,8 @@
 #ifndef _TCSS_H_
 #define _TCSS_H_
 
+#include <intelblocks/gpio.h>
+
 /* PMC IPC related offsets and commands */
 #define PMC_IPC_USBC_CMD_ID		0xA7
 #define PMC_IPC_USBC_SUBCMD_ID		0x0
@@ -136,7 +138,17 @@ struct tcss_port_map {
 	uint8_t usb3_port; /* USB3 Port Number */
 };
 
-void tcss_configure(void);
+struct typec_aux_bias_pads {
+	gpio_t pad_auxn_dc;
+	gpio_t pad_auxp_dc;
+};
+
+/*
+ * 1) Initialize TCSS muxes to disconnected state
+ * 2) Configure GPIO pads to provide DC Bias on AUX signals
+ * 3) Detect DP-over-Type-C alternate mode
+ */
+void tcss_configure(const struct typec_aux_bias_pads pads[MAX_TYPE_C_PORTS]);
 
 /*
  * Mainboard method to setup any mux config needed for TCSS display operations.
diff --git a/src/soc/intel/common/block/tcss/tcss.c b/src/soc/intel/common/block/tcss/tcss.c
index 6d1f3afd26..da19954b10 100644
--- a/src/soc/intel/common/block/tcss/tcss.c
+++ b/src/soc/intel/common/block/tcss/tcss.c
@@ -4,12 +4,18 @@
 #include <console/console.h>
 #include <device/pci.h>
 #include <intelblocks/pmc_ipc.h>
+#include <intelblocks/systemagent.h>
 #include <intelblocks/tcss.h>
 #include <inttypes.h>
 #include <security/vboot/vboot_common.h>
 #include <soc/pci_devs.h>
+#include <soc/pcr_ids.h>
+#include <soc/tcss.h>
 #include <stdlib.h>
 
+#define BIAS_CTRL_VW_INDEX_SHIFT		16
+#define BIAS_CTRL_BIT_POS_SHIFT			8
+
 static uint32_t tcss_make_conn_cmd(int u, int u3, int u2, int ufp, int hsl,
 					int sbu, int acc)
 {
@@ -307,7 +313,32 @@ static void tcss_configure_dp_mode(const struct tcss_port_map *port_map, size_t
 	}
 }
 
-void tcss_configure(void)
+static uint32_t calc_bias_ctrl_reg_value(gpio_t pad)
+{
+	unsigned int vw_index, vw_bit;
+	const unsigned int cpu_pid = gpio_get_pad_cpu_portid(pad);
+	if (!gpio_get_vw_info(pad, &vw_index, &vw_bit) || !cpu_pid)
+		return 0;
+
+	return vw_index << BIAS_CTRL_VW_INDEX_SHIFT |
+		vw_bit << BIAS_CTRL_BIT_POS_SHIFT |
+		cpu_pid;
+}
+
+static void tcss_configure_aux_bias_pads(
+	const struct typec_aux_bias_pads pads[MAX_TYPE_C_PORTS])
+{
+	for (size_t i = 0; i < MAX_TYPE_C_PORTS; i++) {
+		if (pads[i].pad_auxn_dc && pads[i].pad_auxp_dc) {
+			REGBAR32(PID_IOM, IOM_AUX_BIAS_CTRL_PULLUP_OFFSET(i)) =
+				calc_bias_ctrl_reg_value(pads[i].pad_auxp_dc);
+			REGBAR32(PID_IOM, IOM_AUX_BIAS_CTRL_PULLDOWN_OFFSET(i)) =
+				calc_bias_ctrl_reg_value(pads[i].pad_auxn_dc);
+		}
+	}
+}
+
+void tcss_configure(const struct typec_aux_bias_pads aux_bias_pads[MAX_TYPE_C_PORTS])
 {
 	const struct tcss_port_map *port_map;
 	size_t num_ports;
@@ -320,6 +351,9 @@ void tcss_configure(void)
 	for (i = 0; i < num_ports; i++)
 		tcss_init_mux(i, &port_map[i]);
 
+	/* This should be performed before alternate modes are entered */
+	tcss_configure_aux_bias_pads(aux_bias_pads);
+
 	if (CONFIG(ENABLE_TCSS_DISPLAY_DETECTION))
 		tcss_configure_dp_mode(port_map, num_ports);
 }