drivers/intel/usb4: Add driver for USB4 retimer device

The USB4 retimer device needs to declare a _DSM with specific functions
that allow for GPIO control to turn off the power when an external
device is not connected.  This driver allows the mainboard to provide
the GPIO that is connected to the power control.

BUG=b:156957424

Change-Id: Icfb85dc3c0885d828aba3855a66109043250ab86
Signed-off-by: Duncan Laurie <dlaurie@google.com>
Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44918
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

4 files changed, 158 insertions, 0 deletions

diff --git a/src/drivers/intel/usb4/retimer/Kconfig b/src/drivers/intel/usb4/retimer/Kconfig
new file mode 100644
index 0000000000..eee8fe1bed
--- /dev/null
+++ b/src/drivers/intel/usb4/retimer/Kconfig
@@ -0,0 +1,8 @@
+config DRIVERS_INTEL_USB4_RETIMER
+	bool
+	depends on HAVE_ACPI_TABLES
+	help
+	   A retimer is a device that retransmits a fresh copy of the signal it
+	   receives, by doing CDR and retransmitting the data (i.e., it is
+	   protocol-aware). If your mainboard has a USB4 retimer (usually
+	   located close to the USB4 ports), then select this driver.
diff --git a/src/drivers/intel/usb4/retimer/Makefile.inc b/src/drivers/intel/usb4/retimer/Makefile.inc
new file mode 100644
index 0000000000..bca23aa3bf
--- /dev/null
+++ b/src/drivers/intel/usb4/retimer/Makefile.inc
@@ -0,0 +1 @@
+ramstage-$(CONFIG_DRIVERS_INTEL_USB4_RETIMER) += retimer.c
diff --git a/src/drivers/intel/usb4/retimer/chip.h b/src/drivers/intel/usb4/retimer/chip.h
new file mode 100644
index 0000000000..789d824a81
--- /dev/null
+++ b/src/drivers/intel/usb4/retimer/chip.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef __DRIVERS_INTEL_USB4_RETIMER_H__
+#define __DRIVERS_INTEL_USB4_RETIMER_H__
+
+#include <acpi/acpi_device.h>
+
+struct drivers_intel_usb4_retimer_config {
+	/* GPIO used to control power of retimer device. */
+	struct acpi_gpio power_gpio;
+};
+
+#endif /* __DRIVERS_INTEL_USB4_RETIMER_H__ */
diff --git a/src/drivers/intel/usb4/retimer/retimer.c b/src/drivers/intel/usb4/retimer/retimer.c
new file mode 100644
index 0000000000..be9ec35230
--- /dev/null
+++ b/src/drivers/intel/usb4/retimer/retimer.c
@@ -0,0 +1,136 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <acpi/acpigen.h>
+#include <acpi/acpi_device.h>
+#include <console/console.h>
+#include <device/device.h>
+#include <device/path.h>
+#include <gpio.h>
+#include <string.h>
+#include "chip.h"
+
+/* Unique ID for the retimer _DSM. */
+#define INTEL_USB4_RETIMER_DSM_UUID	"61788900-C470-42BB-80F0-23A313864593"
+
+/*
+ * Arg0: UUID
+ * Arg1: Revision ID (set to 1)
+ * Arg2: Function Index
+ *       0: Query command implemented
+ *       1: Query force power enable state
+ *       2: Set force power state
+ * Arg3: A package containing parameters for the function specified
+ *       by the UUID, revision ID and function index.
+ */
+
+static void usb4_retimer_cb_standard_query(void *arg)
+{
+	/*
+	 * ToInteger (Arg1, Local2)
+	 * If (Local2 == 1) {
+	 *     Return(Buffer() {0x07})
+	 * }
+	 * Return (Buffer() {0x01})
+	 */
+	acpigen_write_to_integer(ARG1_OP, LOCAL2_OP);
+
+	/* Revision 1 supports 2 Functions beyond the standard query */
+	acpigen_write_if_lequal_op_int(LOCAL2_OP, 1);
+	acpigen_write_return_singleton_buffer(0x07);
+	acpigen_pop_len(); /* If */
+
+	/* Other revisions support no additional functions */
+	acpigen_write_return_singleton_buffer(0);
+}
+
+static void usb4_retimer_cb_get_power_state(void *arg)
+{
+	struct acpi_gpio *power_gpio = arg;
+
+	/*
+	 * // Read power gpio into Local0
+	 * Store (\_SB.PCI0.GTXS (power_gpio), Local0)
+	 * Return (Local0)
+	 */
+	acpigen_get_tx_gpio(power_gpio);
+	acpigen_write_return_op(LOCAL0_OP);
+}
+
+static void usb4_retimer_cb_set_power_state(void *arg)
+{
+	struct acpi_gpio *power_gpio = arg;
+
+	/*
+	 * // Get argument for on/off from Arg3[0]
+	 * Local0 = DeRefOf (Arg3[0])
+	 */
+	acpigen_get_package_op_element(ARG3_OP, 0, LOCAL0_OP);
+
+	/*
+	 * If (Local0 == 0) {
+	 *     // Turn power off
+	 *     \_SB.PCI0.CTXS (power_gpio)
+	 * }
+	 */
+	acpigen_write_if_lequal_op_int(LOCAL0_OP, 0);
+	acpigen_disable_tx_gpio(power_gpio);
+	acpigen_pop_len(); /* If */
+
+	/*
+	 * Else {
+	 *     // Turn power on
+	 *     \_SB.PCI0.STXS (power_gpio)
+	 * }
+	 */
+	acpigen_write_else();
+	acpigen_enable_tx_gpio(power_gpio);
+	acpigen_pop_len();
+
+	/* Return (Zero) */
+	acpigen_write_return_integer(0);
+}
+
+static void (*usb4_retimer_callbacks[3])(void *) = {
+	usb4_retimer_cb_standard_query,		/* Function 0 */
+	usb4_retimer_cb_get_power_state,	/* Function 1 */
+	usb4_retimer_cb_set_power_state,	/* Function 2 */
+};
+
+static void usb4_retimer_fill_ssdt(const struct device *dev)
+{
+	const struct drivers_intel_usb4_retimer_config *config = dev->chip_info;
+	const char *scope = acpi_device_scope(dev);
+
+	if (!dev->enabled || !scope || !config)
+		return;
+
+	if (!config->power_gpio.pin_count) {
+		printk(BIOS_ERR, "%s: Power GPIO required for %s\n", __func__, dev_path(dev));
+		return;
+	}
+
+	/* Write the _DSM that toggles power with provided GPIO. */
+	acpigen_write_scope(scope);
+	acpigen_write_dsm(INTEL_USB4_RETIMER_DSM_UUID, usb4_retimer_callbacks,
+			  ARRAY_SIZE(usb4_retimer_callbacks), (void *)&config->power_gpio);
+	acpigen_pop_len(); /* Scope */
+
+	printk(BIOS_INFO, "%s: %s at %s\n", acpi_device_path(dev), dev->chip_ops->name,
+	       dev_path(dev));
+}
+
+static struct device_operations usb4_retimer_dev_ops = {
+	.read_resources	= noop_read_resources,
+	.set_resources	= noop_set_resources,
+	.acpi_fill_ssdt	= usb4_retimer_fill_ssdt,
+};
+
+static void usb4_retimer_enable(struct device *dev)
+{
+	dev->ops = &usb4_retimer_dev_ops;
+}
+
+struct chip_operations drivers_intel_usb4_retimer_ops = {
+	CHIP_NAME("Intel USB4 Retimer")
+	.enable_dev = usb4_retimer_enable
+};