Re: [PATCH v7 08/12] gpio: add ti-ssp gpio driver

From: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
To: Cyril Chemparathy <cyril-l0cyMroinI0@public.gmane.org>
Cc: davinci-linux-open-source-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org,
	dbrownell-Rn4VEauK+AKRv+LV9MX5uipxlwaOVQ5f@public.gmane.org,
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	linus.ml.walleij-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
	broonie-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org,
	rpurdie-Fm38FmjxZ/leoWH0uzbU5w@public.gmane.org,
	alan-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org,
	spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org,
	akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
	lrg-kDsPt+C1G03kYMGBc/C6ZA@public.gmane.org
Subject: Re: [PATCH v7 08/12] gpio: add ti-ssp gpio driver
Date: Thu, 30 Dec 2010 23:16:15 -0700	[thread overview]
Message-ID: <20101231061615.GA3733@angua.secretlab.ca> (raw)
In-Reply-To: <1291733522-3626-9-git-send-email-cyril-l0cyMroinI0@public.gmane.org>

On Tue, Dec 07, 2010 at 09:51:58AM -0500, Cyril Chemparathy wrote:
> TI's SSP controller pins can be directly read and written to behave like a
> GPIO.  This patch adds a GPIO driver that exposes such functionality.
> 
> Signed-off-by: Cyril Chemparathy <cyril-l0cyMroinI0@public.gmane.org>
> ---
>  drivers/gpio/Kconfig       |   10 ++
>  drivers/gpio/Makefile      |    1 +
>  drivers/gpio/ti-ssp-gpio.c |  206 ++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/ti_ssp.h |    4 +
>  4 files changed, 221 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/gpio/ti-ssp-gpio.c
> 
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 3143ac7..05bbe4c 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -128,6 +128,16 @@ config GPIO_VX855
>  	  additional drivers must be enabled in order to use the
>  	  functionality of the device.
>  
> +config GPIO_TI_SSP
> +	tristate "TI Sequencer Serial Port - GPIO Support"
> +	depends on MFD_TI_SSP
> +	help
> +	  Say yes here to support a GPIO interface on TI SSP port pins.
> +	  Each SSP port translates into 4 GPIOs.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called ti-ssp-gpio.
> +
>  comment "I2C GPIO expanders:"
>  
>  config GPIO_MAX7300
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index bdf3dde..0e2a844 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -26,6 +26,7 @@ obj-$(CONFIG_GPIO_PL061)	+= pl061.o
>  obj-$(CONFIG_GPIO_STMPE)	+= stmpe-gpio.o
>  obj-$(CONFIG_GPIO_TC35892)	+= tc35892-gpio.o
>  obj-$(CONFIG_GPIO_TIMBERDALE)	+= timbgpio.o
> +obj-$(CONFIG_GPIO_TI_SSP)	+= ti-ssp-gpio.o
>  obj-$(CONFIG_GPIO_TWL4030)	+= twl4030-gpio.o
>  obj-$(CONFIG_GPIO_UCB1400)	+= ucb1400_gpio.o
>  obj-$(CONFIG_GPIO_XILINX)	+= xilinx_gpio.o
> diff --git a/drivers/gpio/ti-ssp-gpio.c b/drivers/gpio/ti-ssp-gpio.c
> new file mode 100644
> index 0000000..387970e
> --- /dev/null
> +++ b/drivers/gpio/ti-ssp-gpio.c
> @@ -0,0 +1,206 @@
> +/*
> + * Sequencer Serial Port (SSP) based virtual GPIO driver
> + *
> + * Copyright (C) 2010 Texas Instruments Inc
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * 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, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
> + */
> +
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/io.h>
> +#include <linux/err.h>
> +#include <linux/slab.h>
> +#include <linux/gpio.h>
> +#include <linux/platform_device.h>
> +#include <linux/mfd/ti_ssp.h>
> +
> +struct ti_ssp_gpio_chip {
> +	struct gpio_chip		chip;
> +	struct device			*dev;
> +	spinlock_t			lock;
> +	u8				out;
> +	u32				iosel;
> +};
> +
> +#define to_ssp_gpio_chip(c) container_of(c, struct ti_ssp_gpio_chip, chip)
> +
> +static int direction_in(struct gpio_chip *chip, unsigned gpio_num)
> +{
> +	struct ti_ssp_gpio_chip *gpio = to_ssp_gpio_chip(chip);
> +	int error = 0;
> +
> +	spin_lock(&gpio->lock);
> +
> +	gpio->iosel &= ~SSP_PIN_MASK(gpio_num);
> +	gpio->iosel |=  SSP_PIN_SEL(gpio_num, SSP_IN);
> +
> +	error = ti_ssp_set_iosel(gpio->dev, gpio->iosel);
> +
> +	spin_unlock(&gpio->lock);
> +
> +	return error;
> +}
> +
> +static int direction_out(struct gpio_chip *chip, unsigned gpio_num, int val)

All of these static functions still need to have the driver-specific
prefix to avoid any possibility of collisions in the global namespace.
I haven't checked the rest of the patches, but this comment does stand
for the whole series.

>From the rest of this file it looks like ti_ssp_gpio_ is the
appropriate prefix here.

Otherwise this patch looks okay.

g.

> +{
> +	struct ti_ssp_gpio_chip *gpio = to_ssp_gpio_chip(chip);
> +	int error;
> +
> +	spin_lock(&gpio->lock);
> +
> +	gpio->iosel &= ~SSP_PIN_MASK(gpio_num);
> +	gpio->iosel |=  SSP_PIN_SEL(gpio_num, SSP_OUT);
> +
> +	error = ti_ssp_set_iosel(gpio->dev, gpio->iosel);
> +
> +	if (error < 0)
> +		goto error;
> +
> +	if (val)
> +		gpio->out |= BIT(gpio_num);
> +	else
> +		gpio->out &= ~BIT(gpio_num);
> +
> +	error = ti_ssp_raw_write(gpio->dev, gpio->out);
> +
> +error:
> +	spin_unlock(&gpio->lock);
> +	return error;
> +}
> +
> +static int value_get(struct gpio_chip *chip, unsigned gpio_num)
> +{
> +	struct ti_ssp_gpio_chip *gpio = to_ssp_gpio_chip(chip);
> +	int ret;
> +
> +	spin_lock(&gpio->lock);
> +
> +	ret = ti_ssp_raw_read(gpio->dev);
> +	if (ret >= 0)
> +		ret = !!(ret & BIT(gpio_num));
> +
> +	spin_unlock(&gpio->lock);
> +	return ret;
> +}
> +
> +static void value_set(struct gpio_chip *chip, unsigned gpio_num, int val)
> +{
> +	struct ti_ssp_gpio_chip *gpio = to_ssp_gpio_chip(chip);
> +
> +	spin_lock(&gpio->lock);
> +
> +	if (val)
> +		gpio->out |= BIT(gpio_num);
> +	else
> +		gpio->out &= ~BIT(gpio_num);
> +
> +	ti_ssp_raw_write(gpio->dev, gpio->out);
> +
> +	spin_unlock(&gpio->lock);
> +}
> +
> +static int __devinit ti_ssp_gpio_probe(struct platform_device *pdev)
> +{
> +	const struct ti_ssp_gpio_data *pdata = pdev->dev.platform_data;
> +	struct device *dev = &pdev->dev;
> +	struct ti_ssp_gpio_chip *gpio;
> +	int error;
> +
> +	if (!pdata) {
> +		dev_err(dev, "platform data not found\n");
> +		return -EINVAL;
> +	}
> +
> +	gpio = kzalloc(sizeof(*gpio), GFP_KERNEL);
> +	if (!gpio) {
> +		dev_err(dev, "cannot allocate driver data\n");
> +		return -ENOMEM;
> +	}
> +
> +	gpio->dev = dev;
> +	gpio->iosel = SSP_PIN_SEL(0, SSP_IN) | SSP_PIN_SEL(1, SSP_IN) |
> +		      SSP_PIN_SEL(2, SSP_IN) | SSP_PIN_SEL(3, SSP_IN);
> +	error = ti_ssp_set_iosel(gpio->dev, gpio->iosel);
> +	if (error < 0) {
> +		dev_err(dev, "gpio io setup failed (%d)\n", error);
> +		goto error;
> +	}
> +
> +	spin_lock_init(&gpio->lock);
> +	platform_set_drvdata(pdev, gpio);
> +
> +	gpio->chip.base  = pdata->start;
> +	gpio->chip.ngpio = 4;
> +	gpio->chip.dev   = &pdev->dev;
> +	gpio->chip.label = "ti_ssp_gpio";
> +	gpio->chip.owner = THIS_MODULE;
> +	gpio->chip.get   = value_get;
> +	gpio->chip.set   = value_set;
> +	gpio->chip.direction_input  = direction_in;
> +	gpio->chip.direction_output = direction_out;
> +
> +	error = gpiochip_add(&gpio->chip);
> +	if (error < 0) {
> +		dev_err(dev, "gpio chip registration failed (%d)\n", error);
> +		goto error;
> +	}
> +
> +	dev_info(dev, "ssp gpio interface registered\n");
> +	return 0;
> +
> +error:
> +	kfree(gpio);
> +	return error;
> +}
> +
> +static int __devexit ti_ssp_gpio_remove(struct platform_device *pdev)
> +{
> +	struct ti_ssp_gpio_chip *gpio = platform_get_drvdata(pdev);
> +	int error;
> +
> +	error = gpiochip_remove(&gpio->chip);
> +	if (error < 0)
> +		return error;
> +	kfree(gpio);
> +	return 0;
> +}
> +
> +static struct platform_driver ti_ssp_gpio_driver = {
> +	.probe		= ti_ssp_gpio_probe,
> +	.remove		= __devexit_p(ti_ssp_gpio_remove),
> +	.driver		= {
> +		.name	= "ti-ssp-gpio",
> +		.owner	= THIS_MODULE,
> +	},
> +};
> +
> +static int __init ti_ssp_gpio_init(void)
> +{
> +	return platform_driver_register(&ti_ssp_gpio_driver);
> +}
> +module_init(ti_ssp_gpio_init);
> +
> +static void __exit ti_ssp_gpio_exit(void)
> +{
> +	platform_driver_unregister(&ti_ssp_gpio_driver);
> +}
> +module_exit(ti_ssp_gpio_exit);
> +
> +MODULE_DESCRIPTION("GPIO interface for TI-SSP");
> +MODULE_AUTHOR("Cyril Chemparathy <cyril-l0cyMroinI0@public.gmane.org>");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:ti-ssp-gpio");
> diff --git a/include/linux/mfd/ti_ssp.h b/include/linux/mfd/ti_ssp.h
> index dbb4b43..10c65bb 100644
> --- a/include/linux/mfd/ti_ssp.h
> +++ b/include/linux/mfd/ti_ssp.h
> @@ -38,6 +38,10 @@ struct ti_ssp_spi_data {
>  	void		(*select)(int cs);
>  };
>  
> +struct ti_ssp_gpio_data {
> +	int		start;
> +};
> +
>  /*
>   * Sequencer port IO pin configuration bits.  These do not correlate 1-1 with
>   * the hardware.  The iosel field in the port data combines iosel1 and iosel2,
> -- 
> 1.7.1
> 
> 
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