mb/google/volteer: ACPI nodes for volteer2_ti50

Unique among the Volteer devices, the volteer2_ti50 variant connects to
the TPM via I2C.  This CL introduces the proper devicestree declarations
for the Linux kernel to recognize that.

overridetree.cb is shared between "sub"-variants volteer2 and
volteer2_ti50, so both will have two TPM nodes, the I2C being disabled
by default.  The odd _ti50 variant then has code in variant.c to enable
the I2C node and disable the SPI node.

BUG=b:173461736
TEST=abuild -t GOOGLE_VOLTEER2{_TI50,} -c max -x

Change-Id: I5576a595bbabc34c62b768f8b3439e35ff6bcf7b
Signed-off-by: Jes Bodi Klinke <jbk@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/48223
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

1 files changed, 33 insertions, 0 deletions

diff --git a/src/mainboard/google/volteer/variants/volteer2/variant.c b/src/mainboard/google/volteer/variants/volteer2/variant.c
new file mode 100644
index 0000000000..057bb8ad65
--- /dev/null
+++ b/src/mainboard/google/volteer/variants/volteer2/variant.c
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <baseboard/variants.h>
+#include <soc/pci_devs.h>
+#include <acpi/acpi_device.h>
+
+extern struct chip_operations drivers_i2c_tpm_ops;
+
+static bool match_i2c_tpm(DEVTREE_CONST struct device *dev)
+{
+	return dev->chip_ops == &drivers_i2c_tpm_ops;
+}
+
+/*
+ * This function runs only on the volteer_ti50 variant, which has the GSC on a
+ * reworked I2C bus.
+ */
+static void devtree_enable_i2c_tpm(void)
+{
+	struct device *spi_tpm = pcidev_path_on_root(PCH_DEVFN_GSPI0)->link_list->children;
+	struct device *i2c_tpm = dev_find_matching_device_on_bus(
+		pcidev_path_on_root(PCH_DEVFN_I2C1)->link_list, match_i2c_tpm);
+	if (!i2c_tpm || !spi_tpm)
+		return;
+	spi_tpm->enabled = 0;
+	i2c_tpm->enabled = 1;
+}
+
+void variant_devtree_update(void)
+{
+	if (CONFIG(MAINBOARD_HAS_I2C_TPM_CR50))
+		devtree_enable_i2c_tpm();
+}