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Message-ID: <AANLkTinS+bH+u-x0jEcMgN+uK-__65TNNGg6uQA55TSv@mail.gmail.com>
Date: Tue, 19 Oct 2010 09:26:42 +0200
From: Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
To: Florian Fainelli <florian@...nwrt.org>
Cc: David Brownell <david-b@...bell.net>, Willy Tarreau <w@....eu>,
linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
Samuel Ortiz <sameo@...ux.intel.com>,
Miguel Gaio <miguel.gaio@...xo.com>,
dbrownell@...rs.sourceforge.net, Juhos Gabor <juhosg@...nwrt.org>
Subject: Re: [PATCH v5] GPIO: add support for 74x164 serial-in/parallel-out
8-bit shift register
On Mon, Oct 18, 2010 at 9:35 PM, Florian Fainelli <florian@...nwrt.org> wrote:
> From: Miguel Gaio <miguel.gaio@...xo.com>
>
> This patch adds support for generic 74x164 serial-in/parallel-out 8-bits
> shift register. This driver can be used as a GPIO output expander.
>
> Signed-off-by: Miguel Gaio <miguel.gaio@...xo.com>
> Signed-off-by: Juhos Gabor <juhosg@...nwrt.org>
> Signed-off-by: Florian Fainelli <florian@...nwrt.org>
> ---
> Changes since v1:
> - renamed nxp_ to gen_ since this driver is generic to all 74HC164 chips
> - added comment on this driver not handling the 74HC164 daisy-chaining
> - renamed misused GPIO expanders to Shift registers
>
> Changes since v2:
> - rename 74hc164 to 74x164
>
> Changes since v3:
> - support daisy-chaining of 74x164 up to 32 gpios
>
> Changes since v4:
> - converted to a SPI device driver
>
> diff --git a/drivers/gpio/74x164.c b/drivers/gpio/74x164.c
> new file mode 100644
> index 0000000..ebb183f
> --- /dev/null
> +++ b/drivers/gpio/74x164.c
> @@ -0,0 +1,184 @@
> +/*
> + * 74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver
> + *
> + * Copyright (C) 2010 Gabor Juhos <juhosg@...nwrt.org>
> + * Copyright (C) 2010 Miguel Gaio <miguel.gaio@...xo.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/init.h>
> +#include <linux/mutex.h>
> +#include <linux/spi/spi.h>
> +#include <linux/spi/74x164.h>
> +#include <linux/gpio.h>
> +#include <linux/slab.h>
> +
> +#define GEN_74X164_GPIO_COUNT 8
> +
> +
> +struct gen_74x164_chip {
> + struct spi_device *spi;
> + struct gpio_chip gpio_chip;
> + struct mutex lock;
> + u8 port_config;
> +};
> +
> +static void gen_74x164_set_value(struct gpio_chip *, unsigned, int);
> +
> +static struct gen_74x164_chip *gpio_to_chip(struct gpio_chip *gc)
> +{
> + return container_of(gc, struct gen_74x164_chip, gpio_chip);
> +}
> +
> +static int __gen_74x164_write_config(struct gen_74x164_chip *chip)
> +{
> + return spi_write(chip->spi,
> + &chip->port_config, sizeof(chip->port_config));
> +}
> +
> +static int gen_74x164_direction_output(struct gpio_chip *gc,
> + unsigned offset, int val)
> +{
> + gen_74x164_set_value(gc, offset, val);
> + return 0;
> +}
> +
> +static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset)
> +{
> + struct gen_74x164_chip *chip = gpio_to_chip(gc);
> + int ret;
> +
> + mutex_lock(&chip->lock);
> + ret = (chip->port_config >> offset) & 0x1;
> + mutex_unlock(&chip->lock);
> +
> + return ret;
> +}
> +
> +static void gen_74x164_set_value(struct gpio_chip *gc,
> + unsigned offset, int val)
> +{
> + struct gen_74x164_chip *chip = gpio_to_chip(gc);
> + bool refresh;
> +
> + mutex_lock(&chip->lock);
> + if (val)
> + chip->port_config |= (1 << offset);
> + else
> + chip->port_config &= ~(1 << offset);
set_bit(), clear_bit() ?
> +
> + __gen_74x164_write_config(chip);
> + mutex_unlock(&chip->lock);
> +}
> +
> +static int __devinit gen_74x164_probe(struct spi_device *spi)
> +{
> + struct gen_74x164_chip *chip;
> + struct gen_74x164_chip_platform_data *pdata;
> + int ret;
> +
> + pdata = spi->dev.platform_data;
> + if (!pdata || !pdata->base) {
> + dev_dbg(&spi->dev, "incorrect or missing platform data\n");
> + return -EINVAL;
> + }
> +
> + /*
> + * bits_per_word cannot be configured in platform data
> + */
> + spi->bits_per_word = 8;
> +
> + ret = spi_setup(spi);
> + if (ret < 0)
> + return ret;
> +
> + chip = kzalloc(sizeof(*chip), GFP_KERNEL);
> + if (!chip)
> + return -ENOMEM;
> +
> + mutex_init(&chip->lock);
> +
> + dev_set_drvdata(&spi->dev, chip);
> +
> + chip->spi = spi;
> +
> + chip->gpio_chip.label = GEN_74X164_DRIVER_NAME,
> + chip->gpio_chip.direction_output = gen_74x164_direction_output;
> + chip->gpio_chip.get = gen_74x164_get_value;
> + chip->gpio_chip.set = gen_74x164_set_value;
> + chip->gpio_chip.base = pdata->base;
> + chip->gpio_chip.ngpio = GEN_74X164_GPIO_COUNT;
> + chip->gpio_chip.can_sleep = 1;
> + chip->gpio_chip.dev = &spi->dev;
> + chip->gpio_chip.owner = THIS_MODULE;
> +
> + ret = __gen_74x164_write_config(chip);
> + if (ret) {
> + dev_err(&spi->dev, "Failed writing: %d\n", ret);
> + goto exit_destroy;
> + }
> +
> + ret = gpiochip_add(&chip->gpio_chip);
> + if (ret)
> + goto exit_destroy;
> +
> + return ret;
> +
> +exit_destroy:
> + dev_set_drvdata(&spi->dev, NULL);
> + mutex_destroy(&chip->lock);
> + kfree(chip);
> + return ret;
> +}
> +
> +static int gen_74x164_remove(struct spi_device *spi)
> +{
> + struct gen_74x164_chip *chip;
> + int ret;
> +
> + chip = dev_get_drvdata(&spi->dev);
> + if (chip == NULL)
> + return -ENODEV;
> +
> + dev_set_drvdata(&spi->dev, NULL);
> +
> + ret = gpiochip_remove(&chip->gpio_chip);
> + if (!ret) {
> + mutex_destroy(&chip->lock);
> + kfree(chip);
> + } else
> + dev_err(&spi->dev, "Failed to remove the GPIO controller: %d\n",
> + ret);
> +
> + return ret;
> +}
> +
> +static struct spi_driver gen_74x164_driver = {
> + .driver = {
> + .name = GEN_74X164_DRIVER_NAME,
> + .owner = THIS_MODULE,
> + },
> + .probe = gen_74x164_probe,
> + .remove = __devexit_p(gen_74x164_remove),
> +};
> +
> +static int __init gen_74x164_init(void)
> +{
> + return spi_register_driver(&gen_74x164_driver);
> +}
> +subsys_initcall(gen_74x164_init);
> +
> +static void __exit gen_74x164_exit(void)
> +{
> + spi_unregister_driver(&gen_74x164_driver);
> +}
> +module_exit(gen_74x164_exit);
> +
> +MODULE_AUTHOR("Gabor Juhos <juhosg@...nwrt.org>");
> +MODULE_AUTHOR("Miguel Gaio <miguel.gaio@...xo.com>");
> +MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register");
> +MODULE_LICENSE("GPL v2");
> +
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 510aa20..614965c 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -339,6 +339,14 @@ config GPIO_MC33880
> SPI driver for Freescale MC33880 high-side/low-side switch.
> This provides GPIO interface supporting inputs and outputs.
>
> +config GPIO_74X164
> + tristate "74x164 serial-in/parallel-out 8-bits shift register"
> + depends on SPI_MASTER
> + help
> + Platform driver for 74x164 compatible serial-in/parallel-out
> + 8-outputs shift registers. This driver can be used to provide access
> + to more gpio outputs.
> +
> comment "AC97 GPIO expanders:"
>
> config GPIO_UCB1400
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index fc6019d..60456a4 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -17,6 +17,7 @@ obj-$(CONFIG_GPIO_MAX7301) += max7301.o
> obj-$(CONFIG_GPIO_MAX732X) += max732x.o
> obj-$(CONFIG_GPIO_MC33880) += mc33880.o
> obj-$(CONFIG_GPIO_MCP23S08) += mcp23s08.o
> +obj-$(CONFIG_GPIO_74X164) += 74x164.o
> obj-$(CONFIG_GPIO_PCA953X) += pca953x.o
> obj-$(CONFIG_GPIO_PCF857X) += pcf857x.o
> obj-$(CONFIG_GPIO_PL061) += pl061.o
> diff --git a/include/linux/spi/74x164.h b/include/linux/spi/74x164.h
> new file mode 100644
> index 0000000..d85c52f
> --- /dev/null
> +++ b/include/linux/spi/74x164.h
> @@ -0,0 +1,11 @@
> +#ifndef LINUX_SPI_74X164_H
> +#define LINUX_SPI_74X164_H
> +
> +#define GEN_74X164_DRIVER_NAME "74x164"
> +
> +struct gen_74x164_chip_platform_data {
> + /* number assigned to the first GPIO */
> + unsigned base;
> +};
> +
> +#endif
>
>
> --
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