3 files changed, 79 insertions, 1 deletions
diff --git a/src/mainboard/google/sarien/Kconfig b/src/mainboard/google/sarien/Kconfig
index dc8f486104..4aea9f7470 100644
--- a/src/mainboard/google/sarien/Kconfig
+++ b/src/mainboard/google/sarien/Kconfig
@@ -97,6 +97,11 @@ config DEVICETREE
 	string
 	default "variants/$(CONFIG_VARIANT_DIR)/devicetree.cb"
 
+config TOUCHSCREEN_HID
+	string "Specify the touchscreen HID enabled for the OS"
+	default "WCOM48E2" if BOARD_GOOGLE_ARCADA
+	default "NONE" if BOARD_GOOGLE_SARIEN
+
 config VBOOT
 	select HAS_RECOVERY_MRC_CACHE
 	select MRC_CLEAR_NORMAL_CACHE_ON_RECOVERY_RETRAIN
diff --git a/src/mainboard/google/sarien/variants/sarien/Makefile.inc b/src/mainboard/google/sarien/variants/sarien/Makefile.inc
index 2bf028eb1f..fa5b2ea36a 100644
--- a/src/mainboard/google/sarien/variants/sarien/Makefile.inc
+++ b/src/mainboard/google/sarien/variants/sarien/Makefile.inc
@@ -14,6 +14,6 @@
 ##
 
 bootblock-y += gpio.c
-ramstage-y += gpio.c
+ramstage-y += gpio.c ramstage.c
 romstage-y += gpio.c
 verstage-y += gpio.c
diff --git a/src/mainboard/google/sarien/variants/sarien/ramstage.c b/src/mainboard/google/sarien/variants/sarien/ramstage.c
new file mode 100644
index 0000000000..ab79678f9a
--- /dev/null
+++ b/src/mainboard/google/sarien/variants/sarien/ramstage.c
@@ -0,0 +1,73 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2019 Google LLC
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <bootstate.h>
+#include <console/console.h>
+#include <device/device.h>
+#include <drivers/i2c/hid/chip.h>
+#include <drivers/vpd/vpd.h>
+#include <soc/pci_devs.h>
+#include <string.h>
+
+/*
+ * This board may have different touchscreen devices that are at the
+ * same I2C slave address but need different drivers or ACPI configuration.
+ *
+ * The default touchscreen to be enabled is specified in Kconfig by the
+ * ACPI HID of the device.  If a board is connected to a different
+ * touchscreen device it can be enabled in Kconfig or by setting the
+ * VPD key 'touchscreen_hid'.
+ */
+
+#define TOUCHSCREEN_I2C_ADDR	0x10
+#define TOUCHSCREEN_VPD_KEY	"touchscreen_hid"
+
+static void disable_unused_touchscreen(void *unused)
+{
+	struct device *i2c0 = PCH_DEV_I2C0;
+	struct bus *i2c_slaves = i2c0->link_list;
+	struct device *slave = i2c_slaves->children;
+	char touchscreen_hid[9] = CONFIG_TOUCHSCREEN_HID;
+	struct drivers_i2c_hid_config *info;
+
+	/* Look for VPD key that indicates which touchscreen is present */
+	if (IS_ENABLED(CONFIG_VPD) &&
+	    !vpd_gets(TOUCHSCREEN_VPD_KEY, touchscreen_hid,
+		      ARRAY_SIZE(touchscreen_hid), VPD_ANY))
+		printk(BIOS_INFO, "%s: VPD key '%s' not found, default to %s\n",
+		       __func__, TOUCHSCREEN_VPD_KEY, touchscreen_hid);
+
+	/* Go through all I2C slave devices on this bus */
+	while (slave) {
+		/* Find all the I2C slaves with the matching address */
+		if (slave->path.type == DEVICE_PATH_I2C &&
+		    slave->path.i2c.device == TOUCHSCREEN_I2C_ADDR) {
+			info = slave->chip_info;
+			/* Disable all devices except the matching HID */
+			if (strncmp(info->generic.hid, touchscreen_hid,
+				    ARRAY_SIZE(touchscreen_hid))) {
+				printk(BIOS_INFO, "%s: Disable %s\n", __func__,
+				       info->generic.hid);
+				slave->enabled = 0;
+			} else {
+				printk(BIOS_INFO, "%s: Enable %s\n", __func__,
+				       info->generic.hid);
+			}
+		}
+		slave = slave->sibling;
+	}
+}
+BOOT_STATE_INIT_ENTRY(BS_WRITE_TABLES, BS_ON_ENTRY,
+		      disable_unused_touchscreen, NULL);