Re: [RFC/PATCH] extcon: otg_gpio: add driver for USB OTG port controlled by GPIO(s)

Peter Chen
2014-12-23T02:34:11Z

On Mon, Dec 22, 2014 at 02:43:37PM -0800, David Cohen wrote:
> Some platforms have an USB OTG port fully (or partially) controlled by
> GPIOs:
>
> (1) USB ID is connected directly to GPIO
>
> Optionally:
> (2) VBUS is enabled by a GPIO (when ID is grounded)
> (3) Platform has 2 USB controllers connected to same port: one for
> device and one for host role. D+/- are switched between phys
> by GPIO.

Would you explain how it works? Choosing controller runtime?

>
> As per initial version, this driver has the duty to control whether
> USB-Host cable is plugged in or not:

You mean Micro-AB cable, right?

> - If yes, OTG port is configured for host role
> - If no, by standard, the OTG port is configured for device role
>
> Signed-off-by: David Cohen <david.a.cohen@linux.intel.com>
> ---
>
> Hi,
>
> Some Intel Bay Trail boards have an unusual way to handle the USB OTG port:
> - The USB ID pin is connected directly to GPIO on SoC
> - When in host role, VBUS is provided by enabling a GPIO
> - Device and host roles are supported by 2 independent controllers with D+/-
> pins from port switched between different phys according a GPIO level.
>
> The ACPI table describes this USB port as a (virtual) device with all the
> necessary GPIOs. This driver implements support to this virtual device as an
> extcon class driver. All drivers that depend on the USB OTG port state (USB phy,
> PMIC, charge detection) will listen to extcon events.
>
> Comments are welcome.
>
> Br, David
> ---
>
> drivers/extcon/Kconfig | 8 ++
> drivers/extcon/Makefile | 1 +
> drivers/extcon/extcon-otg_gpio.c | 200 +++++++++++++++++++++++++++++++++++++++
> 3 files changed, 209 insertions(+)
> create mode 100644 drivers/extcon/extcon-otg_gpio.c
>
> diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig
> index 6a1f7de6fa54..e8010cda4642 100644
> --- a/drivers/extcon/Kconfig
> +++ b/drivers/extcon/Kconfig
> @@ -93,4 +93,12 @@ config EXTCON_SM5502
> Silicon Mitus SM5502. The SM5502 is a USB port accessory
> detector and switch.
>
> +config EXTCON_OTG_GPIO
> + tristate "VIRTUAL USB OTG PORT support"
> + depends on GPIOLIB
> + help
> + Say Y here to enable support for virtual USB OTG port device
> + controlled by GPIOs. This driver can be used when at least USB ID pin
> + is connected directly to GPIO.
> +
> endif # MULTISTATE_SWITCH
> diff --git a/drivers/extcon/Makefile b/drivers/extcon/Makefile
> index 0370b42e5a27..9e81088c6584 100644
> --- a/drivers/extcon/Makefile
> +++ b/drivers/extcon/Makefile
> @@ -12,3 +12,4 @@ obj-$(CONFIG_EXTCON_MAX8997) += extcon-max8997.o
> obj-$(CONFIG_EXTCON_PALMAS) += extcon-palmas.o
> obj-$(CONFIG_EXTCON_RT8973A) += extcon-rt8973a.o
> obj-$(CONFIG_EXTCON_SM5502) += extcon-sm5502.o
> +obj-$(CONFIG_EXTCON_OTG_GPIO) += extcon-otg_gpio.o
> diff --git a/drivers/extcon/extcon-otg_gpio.c b/drivers/extcon/extcon-otg_gpio.c
> new file mode 100644
> index 000000000000..c5ee765a5f4f
> --- /dev/null
> +++ b/drivers/extcon/extcon-otg_gpio.c
> @@ -0,0 +1,200 @@
> +/*
> + * Virtual USB OTG Port driver controlled by gpios
> + *
> + * Copyright (c) 2014, Intel Corporation.
> + * Author: David Cohen <david.a.cohen@linux.intel.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * 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 <linux/acpi.h>
> +#include <linux/extcon.h>
> +#include <linux/gpio.h>
> +#include <linux/interrupt.h>
> +#include <linux/platform_device.h>
> +
> +#define DRV_NAME "usb_otg_port"
> +
> +struct vuport {
> + struct device *dev;
> + struct gpio_desc *gpio_vbus_en;
> + struct gpio_desc *gpio_usb_id;
> + struct gpio_desc *gpio_usb_mux;
> +
> + struct extcon_dev edev;
> +};
> +
> +static const char *const vuport_extcon_cable[] = {
> + [0] = "USB-Host",
> + NULL,
> +};
> +
> +/*
> + * If id == 1, USB port should be set to peripheral
> + * if id == 0, USB port should be set to host
> + *
> + * Peripheral: set USB mux to peripheral and disable VBUS
> + * Host: set USB mux to host and enable VBUS
> + */
> +static void vuport_set_port(struct vuport *vup, int id)
> +{
> + int mux_val = id;
> + int vbus_val = !id;
> +
> + if (!IS_ERR(vup->gpio_usb_mux))
> + gpiod_direction_output(vup->gpio_usb_mux, mux_val);
> +
> + if (!IS_ERR(vup->gpio_vbus_en))
> + gpiod_direction_output(vup->gpio_vbus_en, vbus_val);
> +}
> +
> +static void vuport_do_usb_id(struct vuport *vup)
> +{
> + int id = gpiod_get_value(vup->gpio_usb_id);
> +
> + dev_info(vup->dev, "USB PORT ID: %s\n", id ? "PERIPHERAL" : "HOST");

dev_dbg

> +
> + /*
> + * id == 1: PERIPHERAL
> + * id == 0: HOST
> + */
> + vuport_set_port(vup, id);
> +
> + /*
> + * id == 0: HOST connected
> + * id == 1: Host disconnected
> + */
> + extcon_set_cable_state(&vup->edev, "USB-Host", !id);
> +}
> +
> +static irqreturn_t vuport_thread_isr(int irq, void *priv)
> +{
> + struct vuport *vup = priv;
> +
> + vuport_do_usb_id(vup);
> + return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t vuport_isr(int irq, void *priv)
> +{
> + return IRQ_WAKE_THREAD;
> +}
> +
> +#define VUPORT_GPIO_USB_ID 0
> +#define VUPORT_GPIO_VBUS_EN 1
> +#define VUPORT_GPIO_USB_MUX 2
> +static int vuport_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct vuport *vup;
> + int ret;
> +
> + vup = devm_kzalloc(dev, sizeof(*vup), GFP_KERNEL);
> + if (!vup) {
> + dev_err(dev, "cannot allocate private data\n");
> + return -ENOMEM;
> + }
> + vup->dev = dev;
> +
> + vup->gpio_usb_id = devm_gpiod_get_index(dev, "id", VUPORT_GPIO_USB_ID);
> + if (IS_ERR(vup->gpio_usb_id)) {
> + dev_err(dev, "cannot request USB ID GPIO: ret = %ld\n",
> + PTR_ERR(vup->gpio_usb_id));
> + return PTR_ERR(vup->gpio_usb_id);
> + }
> +
> + ret = gpiod_direction_input(vup->gpio_usb_id);
> + if (ret < 0) {
> + dev_err(dev, "cannot set input direction to USB ID GPIO: ret = %d\n",
> + ret);
> + return ret;
> + }
> +
> + vup->gpio_vbus_en = devm_gpiod_get_index(dev, "vbus en",
> + VUPORT_GPIO_VBUS_EN);
> + if (IS_ERR(vup->gpio_vbus_en))
> + dev_info(dev, "cannot request VBUS EN GPIO, skipping it.\n");
> +
> + vup->gpio_usb_mux = devm_gpiod_get_index(dev, "usb mux",
> + VUPORT_GPIO_USB_MUX);
> + if (IS_ERR(vup->gpio_usb_mux))
> + dev_info(dev, "cannot request USB USB MUX, skipping it.\n");

Using dev_err

> +
> + /* register extcon device */
> + vup->edev.dev.parent = dev;
> + vup->edev.supported_cable = vuport_extcon_cable;
> + ret = extcon_dev_register(&vup->edev);
> + if (ret < 0) {
> + dev_err(dev, "failed to register extcon device: ret = %d\n",
> + ret);
> + return ret;
> + }
> +
> + ret = devm_request_threaded_irq(dev, gpiod_to_irq(vup->gpio_usb_id),
> + vuport_isr, vuport_thread_isr,
> + IRQF_SHARED | IRQF_TRIGGER_RISING |
> + IRQF_TRIGGER_FALLING,
> + dev_name(dev), vup);
> + if (ret < 0) {
> + dev_err(dev, "cannot request IRQ for USB ID GPIO: ret = %d\n",
> + ret);
> + goto irq_err;
> + }
> + vuport_do_usb_id(vup);
> +
> + platform_set_drvdata(pdev, vup);
> +
> + dev_info(dev, "driver successfully probed\n");
> +
> + return 0;
> +
> +irq_err:
> + extcon_dev_unregister(&vup->edev);
> +
> + return ret;
> +}
> +
> +static int vuport_remove(struct platform_device *pdev)
> +{
> + struct vuport *vup = platform_get_drvdata(pdev);
> +
> + extcon_dev_unregister(&vup->edev);
> + return 0;
> +}
> +
> +static struct acpi_device_id vuport_acpi_match[] = {
> + { "INT3496" },
> + { }
> +};
> +MODULE_DEVICE_TABLE(acpi, vuport_acpi_match);
> +
> +static struct platform_driver vuport_driver = {
> + .driver = {
> + .name = DRV_NAME,
> + .acpi_match_table = ACPI_PTR(vuport_acpi_match),
> + },
> + .probe = vuport_probe,
> + .remove = vuport_remove,
> +};
> +
> +static int __init vuport_init(void)
> +{
> + return platform_driver_register(&vuport_driver);
> +}
> +subsys_initcall(vuport_init);
> +
> +static void __exit vuport_exit(void)
> +{
> + platform_driver_unregister(&vuport_driver);
> +}
> +module_exit(vuport_exit);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("David Cohen <david.a.cohen@linux.intel.com>");
> --
> 2.1.1
>

--

Best Regards,
Peter Chen