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

David Cohen
2014-12-23T19:39:12Z

Hi Peter,

Thanks for the review.

On Tue, Dec 23, 2014 at 09:25:18AM +0800, Peter Chen wrote:
> 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?

Both controllers are (indirectly) connected to the same micro B port.
The D+/- goes from the port to a switch operated by a GPIO. From the
switch, D+/- may go to Host controller's phy or Device controller's phy.
Depends on the GPIO level.

>
> >
> > 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?

In my case I'd say micro B. But USB-Host would be any cable or
combination of cables where USB ID is grounded.

>
> > - 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

Agreed.

>
> > +
> > + /*
> > + * 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

That's not really an error, although the IS_ERR() suggests otherwise.
The driver works well if a board doesn't need this mux (I'll add a
comment to state that clear). IMHO either keep dev_info or use dev_dgb
instead?

Br, David

>
> > +
> > + /* 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