[PATCH 2/2] usb: typec: mux: Introduce GPIO-based SBU mux

Bjorn Andersson
2022-08-10T20:45:31Z

A design found in various Qualcomm-based boards is to use a USB switch,
controlled through a pair of GPIO lines to connect, disconnect and
switch the orientation of the SBU lines in USB Type-C applications.

This introduces a generic driver, which implements the typec_switch and
typec_mux interfaces to perform these operations.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
---
drivers/usb/typec/mux/Kconfig | 6 +
drivers/usb/typec/mux/Makefile | 1 +
drivers/usb/typec/mux/gpio-sbu-mux.c | 171 +++++++++++++++++++++++++++
3 files changed, 178 insertions(+)
create mode 100644 drivers/usb/typec/mux/gpio-sbu-mux.c

diff --git a/drivers/usb/typec/mux/Kconfig b/drivers/usb/typec/mux/Kconfig
index 5eb2c17d72c1..c46fa4f9d3df 100644
--- a/drivers/usb/typec/mux/Kconfig
+++ b/drivers/usb/typec/mux/Kconfig
@@ -12,6 +12,12 @@ config TYPEC_MUX_FSA4480
common USB Type-C connector.
If compiled as a module, the module will be named fsa4480.

+config TYPEC_MUX_GPIO_SBU
+ tristate "Generic GPIO based SBU mux for USB Type-C applications"
+ help
+ Say Y or M if your system uses a GPIO based mux for managing the
+ connected state and the swapping of the SBU lines in a Type-C port.
+
config TYPEC_MUX_PI3USB30532
tristate "Pericom PI3USB30532 Type-C cross switch driver"
depends on I2C
diff --git a/drivers/usb/typec/mux/Makefile b/drivers/usb/typec/mux/Makefile
index e52a56c16bfb..dda67e19b58b 100644
--- a/drivers/usb/typec/mux/Makefile
+++ b/drivers/usb/typec/mux/Makefile
@@ -1,5 +1,6 @@
# SPDX-License-Identifier: GPL-2.0

obj-$(CONFIG_TYPEC_MUX_FSA4480) += fsa4480.o
+obj-$(CONFIG_TYPEC_MUX_GPIO_SBU) += gpio-sbu-mux.o
obj-$(CONFIG_TYPEC_MUX_PI3USB30532) += pi3usb30532.o
obj-$(CONFIG_TYPEC_MUX_INTEL_PMC) += intel_pmc_mux.o
diff --git a/drivers/usb/typec/mux/gpio-sbu-mux.c b/drivers/usb/typec/mux/gpio-sbu-mux.c
new file mode 100644
index 000000000000..35f7bd3029a9
--- /dev/null
+++ b/drivers/usb/typec/mux/gpio-sbu-mux.c
@@ -0,0 +1,171 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 Linaro Ltd.
+ */
+
+#include <linux/bits.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/gpio/consumer.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/usb/typec_dp.h>
+#include <linux/usb/typec_mux.h>
+
+struct gpio_sbu_mux {
+ struct gpio_desc *enable_gpio;
+ struct gpio_desc *select_gpio;
+
+ struct typec_switch_dev *sw;
+ struct typec_mux_dev *mux;
+
+ struct mutex lock; /* protect enabled and swapped */
+ bool enabled;
+ bool swapped;
+};
+
+static int gpio_sbu_switch_set(struct typec_switch_dev *sw,
+ enum typec_orientation orientation)
+{
+ struct gpio_sbu_mux *sbu_mux = typec_switch_get_drvdata(sw);
+ bool enabled;
+ bool swapped;
+
+ mutex_lock(&sbu_mux->lock);
+
+ enabled = sbu_mux->enabled;
+
+ switch (orientation) {
+ case TYPEC_ORIENTATION_NONE:
+ enabled = false;
+ break;
+ case TYPEC_ORIENTATION_NORMAL:
+ swapped = false;
+ break;
+ case TYPEC_ORIENTATION_REVERSE:
+ swapped = true;
+ break;
+ }
+
+ if (enabled != sbu_mux->enabled)
+ gpiod_set_value(sbu_mux->enable_gpio, enabled);
+
+ if (swapped != sbu_mux->swapped)
+ gpiod_set_value(sbu_mux->select_gpio, swapped);
+
+ sbu_mux->enabled = enabled;
+ sbu_mux->swapped = swapped;
+
+ mutex_unlock(&sbu_mux->lock);
+
+ return 0;
+}
+
+static int gpio_sbu_mux_set(struct typec_mux_dev *mux,
+ struct typec_mux_state *state)
+{
+ struct gpio_sbu_mux *sbu_mux = typec_mux_get_drvdata(mux);
+
+ mutex_lock(&sbu_mux->lock);
+
+ switch (state->mode) {
+ case TYPEC_STATE_SAFE:
+ case TYPEC_STATE_USB:
+ sbu_mux->enabled = false;
+ break;
+ case TYPEC_DP_STATE_C:
+ case TYPEC_DP_STATE_D:
+ case TYPEC_DP_STATE_E:
+ sbu_mux->enabled = true;
+ break;
+ default:
+ break;
+ }
+
+ gpiod_set_value(sbu_mux->enable_gpio, sbu_mux->enabled);
+
+ mutex_unlock(&sbu_mux->lock);
+
+ return 0;
+}
+
+static int gpio_sbu_mux_probe(struct platform_device *pdev)
+{
+ struct typec_switch_desc sw_desc = { };
+ struct typec_mux_desc mux_desc = { };
+ struct device *dev = &pdev->dev;
+ struct gpio_sbu_mux *sbu_mux;
+
+ sbu_mux = devm_kzalloc(dev, sizeof(*sbu_mux), GFP_KERNEL);
+ if (!sbu_mux)
+ return -ENOMEM;
+
+ mutex_init(&sbu_mux->lock);
+
+ sbu_mux->enable_gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
+ if (IS_ERR(sbu_mux->enable_gpio))
+ return dev_err_probe(dev, PTR_ERR(sbu_mux->enable_gpio),
+ "unable to acquire enable gpio\n");
+
+ sbu_mux->select_gpio = devm_gpiod_get(dev, "select", GPIOD_OUT_LOW);
+ if (IS_ERR(sbu_mux->select_gpio))
+ return dev_err_probe(dev, PTR_ERR(sbu_mux->select_gpio),
+ "unable to acquire select gpio\n");
+
+ sw_desc.drvdata = sbu_mux;
+ sw_desc.fwnode = dev_fwnode(dev);
+ sw_desc.set = gpio_sbu_switch_set;
+
+ sbu_mux->sw = typec_switch_register(dev, &sw_desc);
+ if (IS_ERR(sbu_mux->sw))
+ return dev_err_probe(dev, PTR_ERR(sbu_mux->sw),
+ "failed to register typec switch\n");
+
+ mux_desc.drvdata = sbu_mux;
+ mux_desc.fwnode = dev_fwnode(dev);
+ mux_desc.set = gpio_sbu_mux_set;
+
+ sbu_mux->mux = typec_mux_register(dev, &mux_desc);
+ if (IS_ERR(sbu_mux->mux)) {
+ typec_switch_unregister(sbu_mux->sw);
+ return dev_err_probe(dev, PTR_ERR(sbu_mux->mux),
+ "failed to register typec mux\n");
+ }
+
+ platform_set_drvdata(pdev, sbu_mux);
+
+ return 0;
+}
+
+static int gpio_sbu_mux_remove(struct platform_device *pdev)
+{
+ struct gpio_sbu_mux *sbu_mux = platform_get_drvdata(pdev);
+
+ gpiod_set_value(sbu_mux->enable_gpio, 0);
+
+ typec_mux_unregister(sbu_mux->mux);
+ typec_switch_unregister(sbu_mux->sw);
+
+ return 0;
+}
+
+static const struct of_device_id gpio_sbu_mux_match[] = {
+ { .compatible = "gpio-sbu-mux", },
+ {}
+};
+MODULE_DEVICE_TABLE(of, gpio_sbu_mux_match);
+
+static struct platform_driver gpio_sbu_mux_driver = {
+ .probe = gpio_sbu_mux_probe,
+ .remove = gpio_sbu_mux_remove,
+ .driver = {
+ .name = "gpio_sbu_mux",
+ .of_match_table = gpio_sbu_mux_match,
+ },
+};
+module_platform_driver(gpio_sbu_mux_driver);
+
+MODULE_DESCRIPTION("GPIO based SBU mux driver");
+MODULE_LICENSE("GPL");
--
2.35.1