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Date: Mon, 22 Sep 2014 13:43:57 +0200
From: Johan Hovold <johan@...nel.org>
To: Muthu Mani <muth@...ress.com>
Cc: Samuel Ortiz <sameo@...ux.intel.com>,
Lee Jones <lee.jones@...aro.org>,
Wolfram Sang <wsa@...-dreams.de>, linux-i2c@...r.kernel.org,
Linus Walleij <linus.walleij@...aro.org>,
Alexandre Courbot <gnurou@...il.com>,
linux-gpio@...r.kernel.org, gregkh@...uxfoundation.org,
linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
Rajaram Regupathy <rera@...ress.com>
Subject: Re: [PATCH 3/3] gpio: add support for Cypress CYUSBS234 USB-GPIO
adapter
On Mon, Sep 22, 2014 at 03:04:18PM +0530, Muthu Mani wrote:
> Adds support for USB-GPIO interface of Cypress Semiconductor
> CYUSBS234 USB-Serial Bridge controller.
>
> The GPIO get/set can be done through vendor command
> on control endpoint.
>
> Details about the device can be found at:
> http://www.cypress.com/?rID=84126
>
> Signed-off-by: Muthu Mani <muth@...ress.com>
> Signed-off-by: Rajaram Regupathy <rera@...ress.com>
> ---
> drivers/gpio/Kconfig | 13 +++
> drivers/gpio/Makefile | 1 +
> drivers/gpio/gpio-cyusbs23x.c | 190 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 204 insertions(+)
> create mode 100644 drivers/gpio/gpio-cyusbs23x.c
>
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 9de1515..932e07c 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -886,6 +886,19 @@ config GPIO_BCM_KONA
>
> comment "USB GPIO expanders:"
>
> +config GPIO_CYUSBS23X
> + tristate "CYUSBS23x GPIO support"
> + depends on MFD_CYUSBS23X && USB
> + help
> + Say yes here to access the GPIO signals of Cypress
> + Semiconductor CYUSBS23x USB Serial Bridge Controller.
> +
> + This driver enables the GPIO interface of CYUSBS23x USB Serial
> + Bridge controller.
> +
> + This driver can also be built as a module. If so, the module will be
> + called gpio-cyusbs23x.
> +
> config GPIO_VIPERBOARD
> tristate "Viperboard GPIO a & b support"
> depends on MFD_VIPERBOARD && USB
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index 5d024e3..3ad89f1 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -23,6 +23,7 @@ obj-$(CONFIG_GPIO_BT8XX) += gpio-bt8xx.o
> obj-$(CONFIG_GPIO_CLPS711X) += gpio-clps711x.o
> obj-$(CONFIG_GPIO_CS5535) += gpio-cs5535.o
> obj-$(CONFIG_GPIO_CRYSTAL_COVE) += gpio-crystalcove.o
> +obj-$(CONFIG_GPIO_CYUSBS23X) += gpio-cyusbs23x.o
> obj-$(CONFIG_GPIO_DA9052) += gpio-da9052.o
> obj-$(CONFIG_GPIO_DA9055) += gpio-da9055.o
> obj-$(CONFIG_GPIO_DAVINCI) += gpio-davinci.o
> diff --git a/drivers/gpio/gpio-cyusbs23x.c b/drivers/gpio/gpio-cyusbs23x.c
> new file mode 100644
> index 0000000..8aa3ab6
> --- /dev/null
> +++ b/drivers/gpio/gpio-cyusbs23x.c
> @@ -0,0 +1,190 @@
> +/*
> + * Cypress USB-Serial Bridge Controller GPIO driver
> + *
> + * Copyright (c) 2014 Cypress Semiconductor Corporation.
> + *
> + * Author:
> + * Muthu Mani <muth@...ress.com>
> + *
> + * Additional contributors include:
> + * Rajaram Regupathy <rera@...ress.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.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/errno.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +#include <linux/mutex.h>
> +#include <linux/platform_device.h>
> +
> +#include <linux/usb.h>
> +#include <linux/gpio.h>
> +
> +#include <linux/mfd/cyusbs23x.h>
> +
> +#define CY_GPIO_GET_LEN (2)
> +
> +struct cyusbs_gpio {
> + struct gpio_chip gpio;
> + struct cyusbs23x *cyusbs;
> +};
> +
> +static int cy_gpio_get(struct gpio_chip *chip,
> + unsigned offset)
> +{
> + int ret;
> + char buf[CY_GPIO_GET_LEN];
Buffers used for USB (DMA) transfers cannot be allocated on the stack.
Use kmalloc and friends.
> + __u16 wIndex, wValue;
u16 throughout.
> + struct cyusbs_gpio *gpio =
> + container_of(chip, struct cyusbs_gpio, gpio);
> + struct cyusbs23x *cyusbs = gpio->cyusbs;
> +
> + dev_dbg(&cyusbs->usb_intf->dev, "%s: %d\n", __func__,
> + offset);
> + wValue = offset;
> + wIndex = 0;
> +
> + mutex_lock(&cyusbs->lock);
> + ret = usb_control_msg(cyusbs->usb_dev,
> + usb_rcvctrlpipe(cyusbs->usb_dev, 0),
> + CY_GPIO_GET_VALUE_CMD,
> + USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
> + wValue, wIndex, buf, CY_GPIO_GET_LEN, 2000);
> + mutex_unlock(&cyusbs->lock);
> +
> + dev_dbg(&cyusbs->usb_intf->dev, "%s: %d %02x %02x\n", __func__,
> + ret, buf[0], buf[1]);
> +
> + if (ret == CY_GPIO_GET_LEN) {
> + if (buf[0] == 0)
> + ret = buf[1];
> + else
> + ret = -EINVAL;
> + } else {
> + ret = -EREMOTEIO;
> + }
> +
> + return ret;
> +}
> +
> +static void cy_gpio_set(struct gpio_chip *chip,
> + unsigned offset, int value)
> +{
> + int ret;
> + __u16 wIndex, wValue;
> + struct cyusbs_gpio *gpio =
> + container_of(chip, struct cyusbs_gpio, gpio);
> + struct cyusbs23x *cyusbs = gpio->cyusbs;
> +
> + dev_dbg(&cyusbs->usb_intf->dev, "%s: %d\n", __func__,
> + offset);
> + wValue = offset;
> + wIndex = value;
> +
> + mutex_lock(&cyusbs->lock);
> + ret = usb_control_msg(cyusbs->usb_dev,
> + usb_sndctrlpipe(cyusbs->usb_dev, 0),
> + CY_GPIO_SET_VALUE_CMD,
> + USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
> + wValue, wIndex, NULL, 0, 2000);
> + mutex_unlock(&cyusbs->lock);
> +
> + if (ret < 0)
> + dev_err(&cyusbs->usb_intf->dev, "error setting gpio:%d\n", ret);
> +}
> +
> +static int cy_gpio_direction_input(struct gpio_chip *chip,
> + unsigned offset)
> +{
> + return 0;
Aren't the GPIOs output-only?
> +}
> +
> +static int cy_gpio_direction_output(struct gpio_chip *chip,
> + unsigned offset, int value)
> +{
> + return 0;
> +}
> +
> +static int cyusbs23x_gpio_probe(struct platform_device *pdev)
> +{
> + struct cyusbs23x *cyusbs;
> + struct cyusbs_gpio *cy_gpio;
> + int ret = 0;
> +
> + dev_dbg(&pdev->dev, "%s\n", __func__);
> +
> + cyusbs = dev_get_drvdata(pdev->dev.parent);
> +
> + cy_gpio = devm_kzalloc(&pdev->dev, sizeof(*cy_gpio), GFP_KERNEL);
> + if (cy_gpio == NULL)
> + return -ENOMEM;
> +
> + cy_gpio->cyusbs = cyusbs;
> + /* registering gpio */
> + cy_gpio->gpio.label = "cyusbs23x gpio";
> + cy_gpio->gpio.dev = &pdev->dev;
> + cy_gpio->gpio.owner = THIS_MODULE;
> + cy_gpio->gpio.base = -1;
> + cy_gpio->gpio.ngpio = 12; /* total GPIOs */
I think you need to read out the gpio config from the device eeprom and
implement a request() callback where you verify that a requested gpio is
actually available (mode dependent, and there are never more than 10
gpios availble).
> + cy_gpio->gpio.can_sleep = true;
> + cy_gpio->gpio.set = cy_gpio_set;
> + cy_gpio->gpio.get = cy_gpio_get;
> + cy_gpio->gpio.direction_input = cy_gpio_direction_input;
> + cy_gpio->gpio.direction_output = cy_gpio_direction_output;
> + ret = gpiochip_add(&cy_gpio->gpio);
> + if (ret < 0) {
> + dev_err(cy_gpio->gpio.dev, "could not add gpio");
> + goto error;
> + }
> +
> + platform_set_drvdata(pdev, cy_gpio);
> +
> + dev_dbg(&pdev->dev, "added GPIO\n");
> + return ret;
> +
> +error:
> + dev_dbg(&pdev->dev, "error occured %d\n", ret);
> + return ret;
> +}
> +
> +static int cyusbs23x_gpio_remove(struct platform_device *pdev)
> +{
> + struct cyusbs_gpio *cy_gpio = platform_get_drvdata(pdev);
> +
> + dev_dbg(&pdev->dev, "%s\n", __func__);
> +
> + gpiochip_remove(&cy_gpio->gpio);
> +
> + return 0;
> +}
> +
> +static struct platform_driver cyusbs23x_gpio_driver = {
> + .driver.name = "cyusbs23x-gpio",
> + .driver.owner = THIS_MODULE,
> + .probe = cyusbs23x_gpio_probe,
> + .remove = cyusbs23x_gpio_remove,
> +};
> +
> +static int __init cyusbs23x_gpio_init(void)
> +{
> + return platform_driver_register(&cyusbs23x_gpio_driver);
> +}
> +subsys_initcall(cyusbs23x_gpio_init);
> +
> +static void __exit cyusbs23x_gpio_exit(void)
> +{
> + platform_driver_unregister(&cyusbs23x_gpio_driver);
> +}
> +module_exit(cyusbs23x_gpio_exit);
module_platform_driver
> +
> +MODULE_AUTHOR("Rajaram Regupathy <rera@...ress.com>");
> +MODULE_AUTHOR("Muthu Mani <muth@...ress.com>");
> +MODULE_DESCRIPTION("gpio-cyusbs23x driver v0.1");
> +MODULE_LICENSE("GPL");
Description and license comments from i2c patch apply here as well.
> +MODULE_ALIAS("platform:cyusbs23x-gpio");
> +
Stray new line.
Johan
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