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Subject[PATCH v5 2/7] platform/chrome: cros_typec_switch: Add switch driver
Date
Introduce a driver to configure USB Type-C mode switches and retimers
which are controlled by the Chrome OS EC (Embedded Controller).
This allows Type-C port drivers, as well as alternate mode drivers to
configure their relevant mode switches and retimers according to the
Type-C state they want to achieve.

ACPI devices with ID GOOG001A will bind to this driver.

Currently, we only register a retimer switch with a stub set function.
Subsequent patches will implement the host command set functionality,
and introduce mode switches.

Signed-off-by: Prashant Malani <pmalani@chromium.org>
---

Changes since v4:
- Add ACPI dependency to Kconfig.

Changes since v3:
- No changes.

Changes since v2:
- Fixed missing "static" identifier.
- Removed unnecessary new line for function signature.

Changes since v1:
- No changes.

MAINTAINERS | 1 +
drivers/platform/chrome/Kconfig | 11 ++
drivers/platform/chrome/Makefile | 1 +
drivers/platform/chrome/cros_typec_switch.c | 170 ++++++++++++++++++++
4 files changed, 183 insertions(+)
create mode 100644 drivers/platform/chrome/cros_typec_switch.c

diff --git a/MAINTAINERS b/MAINTAINERS
index b7221f4143cb..6fa4da411275 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4884,6 +4884,7 @@ M: Prashant Malani <pmalani@chromium.org>
L: chrome-platform@lists.linux.dev
S: Maintained
F: drivers/platform/chrome/cros_ec_typec.c
+F: drivers/platform/chrome/cros_typec_switch.c

CHROMEOS EC USB PD NOTIFY DRIVER
M: Prashant Malani <pmalani@chromium.org>
diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
index c45fb376d653..55b68f247f02 100644
--- a/drivers/platform/chrome/Kconfig
+++ b/drivers/platform/chrome/Kconfig
@@ -265,6 +265,17 @@ config CHROMEOS_PRIVACY_SCREEN
this should probably always be built into the kernel to avoid or
minimize drm probe deferral.

+config CROS_TYPEC_SWITCH
+ tristate "ChromeOS EC Type-C Switch Control"
+ depends on MFD_CROS_EC_DEV && TYPEC && ACPI
+ default MFD_CROS_EC_DEV
+ help
+ If you say Y here, you get support for configuring the Chrome OS EC Type C
+ muxes and retimers.
+
+ To compile this driver as a module, choose M here: the module will be
+ called cros_typec_switch.
+
source "drivers/platform/chrome/wilco_ec/Kconfig"

# Kunit test cases
diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
index f7e74a845afc..2950610101f1 100644
--- a/drivers/platform/chrome/Makefile
+++ b/drivers/platform/chrome/Makefile
@@ -12,6 +12,7 @@ obj-$(CONFIG_CHROMEOS_TBMC) += chromeos_tbmc.o
obj-$(CONFIG_CROS_EC) += cros_ec.o
obj-$(CONFIG_CROS_EC_I2C) += cros_ec_i2c.o
obj-$(CONFIG_CROS_EC_ISHTP) += cros_ec_ishtp.o
+obj-$(CONFIG_CROS_TYPEC_SWITCH) += cros_typec_switch.o
obj-$(CONFIG_CROS_EC_RPMSG) += cros_ec_rpmsg.o
obj-$(CONFIG_CROS_EC_SPI) += cros_ec_spi.o
cros_ec_lpcs-objs := cros_ec_lpc.o cros_ec_lpc_mec.o
diff --git a/drivers/platform/chrome/cros_typec_switch.c b/drivers/platform/chrome/cros_typec_switch.c
new file mode 100644
index 000000000000..0d319e315d57
--- /dev/null
+++ b/drivers/platform/chrome/cros_typec_switch.c
@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2022 Google LLC
+ *
+ * This driver provides the ability to configure Type C muxes and retimers which are controlled by
+ * the Chrome OS EC.
+ */
+
+#include <linux/acpi.h>
+#include <linux/module.h>
+#include <linux/platform_data/cros_ec_commands.h>
+#include <linux/platform_device.h>
+#include <linux/usb/typec_retimer.h>
+
+#define DRV_NAME "cros-typec-switch"
+
+/* Handles and other relevant data required for each port's switches. */
+struct cros_typec_port {
+ int port_num;
+ struct typec_retimer *retimer;
+ struct cros_typec_switch_data *sdata;
+};
+
+/* Driver-specific data. */
+struct cros_typec_switch_data {
+ struct device *dev;
+ struct cros_ec_device *ec;
+ struct cros_typec_port *ports[EC_USB_PD_MAX_PORTS];
+};
+
+static int cros_typec_retimer_set(struct typec_retimer *retimer, struct typec_retimer_state *state)
+{
+ return 0;
+}
+
+static void cros_typec_unregister_switches(struct cros_typec_switch_data *sdata)
+{
+ int i;
+
+ for (i = 0; i < EC_USB_PD_MAX_PORTS; i++) {
+ if (!sdata->ports[i])
+ continue;
+ typec_retimer_unregister(sdata->ports[i]->retimer);
+ }
+}
+
+static int cros_typec_register_retimer(struct cros_typec_port *port, struct fwnode_handle *fwnode)
+{
+ struct typec_retimer_desc retimer_desc = {
+ .fwnode = fwnode,
+ .drvdata = port,
+ .name = fwnode_get_name(fwnode),
+ .set = cros_typec_retimer_set,
+ };
+
+ port->retimer = typec_retimer_register(port->sdata->dev, &retimer_desc);
+ if (IS_ERR(port->retimer))
+ return PTR_ERR(port->retimer);
+
+ return 0;
+}
+
+static int cros_typec_register_switches(struct cros_typec_switch_data *sdata)
+{
+ struct cros_typec_port *port = NULL;
+ struct device *dev = sdata->dev;
+ struct fwnode_handle *fwnode;
+ struct acpi_device *adev;
+ unsigned long long index;
+ int ret = 0;
+ int nports;
+
+ nports = device_get_child_node_count(dev);
+ if (nports == 0) {
+ dev_err(dev, "No switch devices found.\n");
+ return -ENODEV;
+ }
+
+ device_for_each_child_node(dev, fwnode) {
+ port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
+ if (!port) {
+ ret = -ENOMEM;
+ goto err_switch;
+ }
+
+ adev = to_acpi_device_node(fwnode);
+ if (!adev) {
+ dev_err(fwnode->dev, "Couldn't get ACPI device handle\n");
+ ret = -ENODEV;
+ goto err_switch;
+ }
+
+ ret = acpi_evaluate_integer(adev->handle, "_ADR", NULL, &index);
+ if (ACPI_FAILURE(ret)) {
+ dev_err(fwnode->dev, "_ADR wasn't evaluated\n");
+ ret = -ENODATA;
+ goto err_switch;
+ }
+
+ if (index < 0 || index >= EC_USB_PD_MAX_PORTS) {
+ dev_err(fwnode->dev, "Invalid port index number: %llu", index);
+ ret = -EINVAL;
+ goto err_switch;
+ }
+ port->sdata = sdata;
+ port->port_num = index;
+ sdata->ports[index] = port;
+
+ ret = cros_typec_register_retimer(port, fwnode);
+ if (ret) {
+ dev_err(dev, "Retimer switch register failed\n");
+ goto err_switch;
+ }
+
+ dev_dbg(dev, "Retimer switch registered for index %llu\n", index);
+ }
+
+ return 0;
+err_switch:
+ cros_typec_unregister_switches(sdata);
+ return ret;
+}
+
+static int cros_typec_switch_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct cros_typec_switch_data *sdata;
+
+ sdata = devm_kzalloc(dev, sizeof(*sdata), GFP_KERNEL);
+ if (!sdata)
+ return -ENOMEM;
+
+ sdata->dev = dev;
+ sdata->ec = dev_get_drvdata(pdev->dev.parent);
+
+ platform_set_drvdata(pdev, sdata);
+
+ return cros_typec_register_switches(sdata);
+}
+
+static int cros_typec_switch_remove(struct platform_device *pdev)
+{
+ struct cros_typec_switch_data *sdata = platform_get_drvdata(pdev);
+
+ cros_typec_unregister_switches(sdata);
+ return 0;
+}
+
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id cros_typec_switch_acpi_id[] = {
+ { "GOOG001A", 0 },
+ {}
+};
+MODULE_DEVICE_TABLE(acpi, cros_typec_switch_acpi_id);
+#endif
+
+static struct platform_driver cros_typec_switch_driver = {
+ .driver = {
+ .name = DRV_NAME,
+ .acpi_match_table = ACPI_PTR(cros_typec_switch_acpi_id),
+ },
+ .probe = cros_typec_switch_probe,
+ .remove = cros_typec_switch_remove,
+};
+
+module_platform_driver(cros_typec_switch_driver);
+
+MODULE_AUTHOR("Prashant Malani <pmalani@chromium.org>");
+MODULE_DESCRIPTION("Chrome OS EC Type C Switch control");
+MODULE_LICENSE("GPL");
--
2.37.1.595.g718a3a8f04-goog
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