Message-ID: <20140922114357.GG5237@localhost>
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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