[PATCH 1/3] usb: misc: generic_onboard_hub: add generic onboard USB HUB driver
Mathieu Poirier
mathieu.poirier at linaro.org
Tue Dec 8 07:36:00 PST 2015
On 7 December 2015 at 18:37, Peter Chen <peter.chen at freescale.com> wrote:
> Current USB HUB driver lacks of platform interfaces to configure
> external signal on HUB chip, eg, the PHY input clock and gpio reset
> pin for HUB, these kinds of HUBs are usually soldered at the board,
> and they are not hot-plug USB devices.
>
> With this patch, the user can configure the HUB's pins at platform
> part (through dts or platform), and these configuration will be
> effective before the USB bus can be used, we use subsys_initcall
> for this driver.
>
> Signed-off-by: Peter Chen <peter.chen at freescale.com>
> ---
> MAINTAINERS | 7 ++
> drivers/usb/misc/Kconfig | 9 ++
> drivers/usb/misc/Makefile | 1 +
> drivers/usb/misc/generic_onboard_hub.c | 162 ++++++++++++++++++++++++++++++++
> include/linux/usb/generic_onboard_hub.h | 11 +++
> 5 files changed, 190 insertions(+)
> create mode 100644 drivers/usb/misc/generic_onboard_hub.c
> create mode 100644 include/linux/usb/generic_onboard_hub.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index e9caa4b..cc1981e 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -11121,6 +11121,13 @@ S: Maintained
> F: Documentation/usb/ohci.txt
> F: drivers/usb/host/ohci*
>
> +USB Generic Onboard HUB Driver
> +M: Peter Chen <Peter.Chen at freescale.com>
> +T: git git://git.kernel.org/pub/scm/linux/kernel/git/peter.chen/usb.git
> +L: linux-usb at vger.kernel.org
> +S: Maintained
> +F: drivers/usb/misc/generic_onboard_hub.c
> +
> USB OTG FSM (Finite State Machine)
> M: Peter Chen <Peter.Chen at freescale.com>
> T: git git://git.kernel.org/pub/scm/linux/kernel/git/peter.chen/usb.git
> diff --git a/drivers/usb/misc/Kconfig b/drivers/usb/misc/Kconfig
> index f7a7fc2..8921cae 100644
> --- a/drivers/usb/misc/Kconfig
> +++ b/drivers/usb/misc/Kconfig
> @@ -268,3 +268,12 @@ config USB_CHAOSKEY
>
> To compile this driver as a module, choose M here: the
> module will be called chaoskey.
> +
> +config USB_ONBOARD_HUB
> + tristate "Generic USB Onboard HUB"
> + help
> + Say Y here if your board has an onboard HUB, and this hub needs
> + to control its PHY clock and reset pin through external signals.
> + If you are not sure, say N.
> +
> + To compile this driver as a module, choose M here.
> diff --git a/drivers/usb/misc/Makefile b/drivers/usb/misc/Makefile
> index 45fd4ac..da52e9a 100644
> --- a/drivers/usb/misc/Makefile
> +++ b/drivers/usb/misc/Makefile
> @@ -29,3 +29,4 @@ obj-$(CONFIG_USB_CHAOSKEY) += chaoskey.o
>
> obj-$(CONFIG_USB_SISUSBVGA) += sisusbvga/
> obj-$(CONFIG_USB_LINK_LAYER_TEST) += lvstest.o
> +obj-$(CONFIG_USB_ONBOARD_HUB) += generic_onboard_hub.o
> diff --git a/drivers/usb/misc/generic_onboard_hub.c b/drivers/usb/misc/generic_onboard_hub.c
> new file mode 100644
> index 0000000..df722a0
> --- /dev/null
> +++ b/drivers/usb/misc/generic_onboard_hub.c
> @@ -0,0 +1,162 @@
> +/*
> + * usb_hub_generic.c The generic onboard USB HUB driver
> + *
> + * Copyright (C) 2015 Freescale Semiconductor, Inc.
> + * Author: Peter Chen <peter.chen at freescale.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 of
> + * the License 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program. If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +/*
> + * This driver is only for the USB HUB devices which need to control
> + * their external pins(clock, reset, etc), and these USB HUB devices
> + * are soldered at the board.
> + */
> +
> +#define DEBUG
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/gpio.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_gpio.h>
> +#include <linux/platform_device.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +#include <linux/usb/generic_onboard_hub.h>
> +
> +struct usb_hub_generic_data {
> + struct clk *clk;
> +};
> +
> +static int usb_hub_generic_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct usb_hub_generic_platform_data *pdata = dev->platform_data;
> + struct usb_hub_generic_data *hub_data;
> + int reset_pol = 0, duration_us = 50, ret = 0;
> + struct gpio_desc *gpiod_reset = NULL;
> +
> + hub_data = devm_kzalloc(dev, sizeof(*hub_data), GFP_KERNEL);
> + if (!hub_data)
> + return -ENOMEM;
> +
> + if (dev->of_node) {
> + struct device_node *node = dev->of_node;
> +
> + hub_data->clk = devm_clk_get(dev, "external_clk");
> + if (IS_ERR(hub_data->clk)) {
> + dev_dbg(dev, "Can't get external clock: %ld\n",
> + PTR_ERR(hub_data->clk));
> + }
Is the intended behaviour to keep going here event when there is an
error? Can the "hub_data" really work without a clock?
> +
> + /*
> + * Try to get the information for HUB reset, the
> + * default setting like below:
> + *
> + * - Reset state is low
> + * - The duration is 50us
> + */
> + if (of_find_property(node, "hub-reset-active-high", NULL))
> + reset_pol = 1;
> +
> + of_property_read_u32(node, "hub-reset-duration-us",
> + &duration_us);
> +
> + gpiod_reset = devm_gpiod_get_optional(dev, "hub-reset",
> + reset_pol ? GPIOD_OUT_HIGH : GPIOD_OUT_LOW);
> + ret = PTR_ERR_OR_ZERO(gpiod_reset);
> + if (ret) {
> + dev_err(dev, "Failed to get reset gpio, err = %d\n",
> + ret);
> + return ret;
> + }
> + } else if (pdata) {
> + hub_data->clk = pdata->ext_clk;
> + duration_us = pdata->gpio_reset_duration_us;
> + reset_pol = pdata->gpio_reset_polarity;
> +
> + if (gpio_is_valid(pdata->gpio_reset)) {
> + ret = devm_gpio_request_one(
> + dev, pdata->gpio_reset, reset_pol
> + ? GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW,
> + dev_name(dev));
> + if (!ret)
> + gpiod_reset = gpio_to_desc(pdata->gpio_reset);
> + }
> + }
> +
> + if (!IS_ERR(hub_data->clk)) {
> + ret = clk_prepare_enable(hub_data->clk);
> + if (ret) {
> + dev_err(dev,
> + "Can't enable external clock: %d\n",
> + ret);
> + return ret;
> + }
> + }
> +
> + if (gpiod_reset) {
> + /* Sanity check */
> + if (duration_us > 1000000)
> + duration_us = 50;
> + usleep_range(duration_us, duration_us + 100);
> + gpiod_set_value(gpiod_reset, reset_pol ? 0 : 1);
What are these hard-coded values? Shouldn't this be taken from the
DT? If not then some comments explaining the values would be
appreciated.
> + }
> +
> + dev_set_drvdata(dev, hub_data);
> + return ret;
> +}
> +
> +static int usb_hub_generic_remove(struct platform_device *pdev)
> +{
> + struct usb_hub_generic_data *hub_data = platform_get_drvdata(pdev);
> +
> + if (!IS_ERR(hub_data->clk))
> + clk_disable_unprepare(hub_data->clk);
> +
> + return 0;
> +}
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id usb_hub_generic_dt_ids[] = {
> + {.compatible = "generic-onboard-hub"},
> + { },
> +};
> +MODULE_DEVICE_TABLE(of, usb_hub_generic_dt_ids);
> +#endif
> +
> +static struct platform_driver usb_hub_generic_driver = {
> + .probe = usb_hub_generic_probe,
> + .remove = usb_hub_generic_remove,
> + .driver = {
> + .name = "usb_hub_generic_onboard",
> + .of_match_table = usb_hub_generic_dt_ids,
> + },
> +};
> +
> +static int __init usb_hub_generic_init(void)
> +{
> + return platform_driver_register(&usb_hub_generic_driver);
> +}
> +subsys_initcall(usb_hub_generic_init);
> +
> +static void __exit usb_hub_generic_exit(void)
> +{
> + platform_driver_unregister(&usb_hub_generic_driver);
> +}
> +module_exit(usb_hub_generic_exit);
> +
> +MODULE_AUTHOR("Peter Chen <peter.chen at freescale.com>");
> +MODULE_DESCRIPTION("Generic Onboard USB HUB driver");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/usb/generic_onboard_hub.h b/include/linux/usb/generic_onboard_hub.h
> new file mode 100644
> index 0000000..1b70ccc
> --- /dev/null
> +++ b/include/linux/usb/generic_onboard_hub.h
> @@ -0,0 +1,11 @@
> +#ifndef __LINUX_USB_GENERIC_HUB_H
> +#define __LINUX_USB_GENERIC_HUB_H
> +
> +struct usb_hub_generic_platform_data {
> + int gpio_reset;
> + int gpio_reset_polarity;
> + int gpio_reset_duration_us;
> + struct clk *ext_clk;
> +};
Please document this structure in accordance with kernel documentation
standards.
> +
> +#endif /* __LINUX_USB_GENERIC_HUB_H */
> --
> 1.9.1
>
> --
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