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Date: Wed, 1 Sep 2010 09:25:50 +0200
From: Florian Fainelli <f.fainelli@...il.com>
To: David Brownell <david-b@...bell.net>
Cc: 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>,
Juhos Gabor <juhosg@...nwrt.org>,
dbrownell@...rs.sourceforge.net
Subject: Re: [PATCH v3] GPIO: add support for 74x164 serial-in/parallel-out 8-bit shift register
On Tuesday 31 August 2010 12:44:07 Florian Fainelli 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
Miguel sent me a 4th version supporting daisy-chaining, I will resubmit it
right away.
>
> diff --git a/drivers/gpio/74x164.c b/drivers/gpio/74x164.c
> new file mode 100644
> index 0000000..9adeed4
> --- /dev/null
> +++ b/drivers/gpio/74x164.c
> @@ -0,0 +1,228 @@
> +/*
> + * 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.
> + *
> + * Note: this driver does not support the way 74x164 chips can be
> + * daisy-chained.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/slab.h>
> +#include <linux/gpio.h>
> +#include <linux/bitops.h>
> +#include <linux/platform_device.h>
> +#include <linux/74x164.h>
> +
> +#define GEN_74X164_NUM_GPIOS 8
> +
> +struct gen_74x164_chip {
> + struct device *parent;
> + struct gpio_chip gpio_chip;
> + struct mutex lock;
> + long mask;
> +};
> +
> +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_direction_input(struct gpio_chip *gc, unsigned
> offset) +{
> + WARN_ON(1);
> + return -EINVAL;
> +}
> +
> +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 = test_bit(offset, &chip->mask);
> + 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;
> + struct gen_74x164_platform_data *pdata;
> + long mask;
> + int refresh;
> + int i;
> +
> + chip = gpio_to_chip(gc);
> + pdata = chip->parent->platform_data;
> +
> + mutex_lock(&chip->lock);
> + if (val)
> + refresh = (test_and_set_bit(offset, &chip->mask) != val);
> + else
> + refresh = (test_and_clear_bit(offset, &chip->mask) != val);
> +
> + if (refresh) {
> + mask = chip->mask;
> + for (i = 8; i > 0; --i, mask <<= 1) {
> + gpio_set_value(pdata->gpio_pin_data, mask & 0x80);
> + gpio_set_value(pdata->gpio_pin_clk, 1);
> + gpio_set_value(pdata->gpio_pin_clk, 0);
> + }
> + }
> + mutex_unlock(&chip->lock);
> +}
> +
> +static int __devinit gen_74x164_probe(struct platform_device *pdev)
> +{
> + struct gen_74x164_platform_data *pdata;
> + struct gen_74x164_chip *chip;
> + struct gpio_chip *gc;
> + int err;
> +
> + pdata = pdev->dev.platform_data;
> + if (pdata == NULL) {
> + dev_dbg(&pdev->dev, "no platform data specified\n");
> + return -EINVAL;
> + }
> +
> + chip = kzalloc(sizeof(struct gen_74x164_chip), GFP_KERNEL);
> + if (chip == NULL) {
> + dev_err(&pdev->dev, "no memory for private data\n");
> + return -ENOMEM;
> + }
> +
> + err = gpio_request(pdata->gpio_pin_clk, dev_name(&pdev->dev));
> + if (err) {
> + dev_err(&pdev->dev, "unable to claim gpio %u, err=%d\n",
> + pdata->gpio_pin_clk, err);
> + goto err_free_chip;
> + }
> +
> + err = gpio_request(pdata->gpio_pin_data, dev_name(&pdev->dev));
> + if (err) {
> + dev_err(&pdev->dev, "unable to claim gpio %u, err=%d\n",
> + pdata->gpio_pin_data, err);
> + goto err_free_clk;
> + }
> +
> + err = gpio_direction_output(pdata->gpio_pin_clk, 0);
> + if (err) {
> + dev_err(&pdev->dev,
> + "unable to set direction of gpio %u, err=%d\n",
> + pdata->gpio_pin_clk, err);
> + goto err_free_data;
> + }
> +
> + err = gpio_direction_output(pdata->gpio_pin_data, 0);
> + if (err) {
> + dev_err(&pdev->dev,
> + "unable to set direction of gpio %u, err=%d\n",
> + pdata->gpio_pin_data, err);
> + goto err_free_data;
> + }
> +
> + chip->parent = &pdev->dev;
> + mutex_init(&chip->lock);
> +
> + gc = &chip->gpio_chip;
> +
> + gc->direction_input = gen_74x164_direction_input;
> + gc->direction_output = gen_74x164_direction_output;
> + gc->get = gen_74x164_get_value;
> + gc->set = gen_74x164_set_value;
> + gc->can_sleep = 1;
> +
> + gc->base = pdata->gpio_base;
> + gc->ngpio = GEN_74X164_NUM_GPIOS;
> + gc->label = dev_name(chip->parent);
> + gc->dev = chip->parent;
> + gc->owner = THIS_MODULE;
> +
> + err = gpiochip_add(&chip->gpio_chip);
> + if (err) {
> + dev_err(&pdev->dev, "unable to add gpio chip, err=%d\n", err);
> + goto err_free_data;
> + }
> +
> + platform_set_drvdata(pdev, chip);
> + return 0;
> +
> +err_free_data:
> + gpio_free(pdata->gpio_pin_data);
> +err_free_clk:
> + gpio_free(pdata->gpio_pin_clk);
> +err_free_chip:
> + kfree(chip);
> + return err;
> +}
> +
> +static int gen_74x164_remove(struct platform_device *pdev)
> +{
> + struct gen_74x164_chip *chip = platform_get_drvdata(pdev);
> + struct gen_74x164_platform_data *pdata = pdev->dev.platform_data;
> +
> + if (chip) {
> + int err;
> +
> + err = gpiochip_remove(&chip->gpio_chip);
> + if (err) {
> + dev_err(&pdev->dev,
> + "unable to remove gpio chip, err=%d\n",
> + err);
> + return err;
> + }
> +
> + gpio_free(pdata->gpio_pin_clk);
> + gpio_free(pdata->gpio_pin_data);
> +
> + kfree(chip);
> + platform_set_drvdata(pdev, NULL);
> + }
> +
> + return 0;
> +}
> +
> +static struct platform_driver gen_74x164_driver = {
> + .probe = gen_74x164_probe,
> + .remove = __devexit_p(gen_74x164_remove),
> + .driver = {
> + .name = GEN_74X164_DRIVER_NAME,
> + .owner = THIS_MODULE,
> + },
> +};
> +
> +static int __init gen_74x164_init(void)
> +{
> + return platform_driver_register(&gen_74x164_driver);
> +}
> +subsys_initcall(gen_74x164_init);
> +
> +static void __exit gen_74x164_exit(void)
> +{
> + platform_driver_unregister(&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");
> +MODULE_ALIAS("platform:" GEN_74X164_DRIVER_NAME);
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 510aa20..fc82c23 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -361,4 +361,13 @@ config GPIO_JANZ_TTL
> This driver provides support for driving the pins in output
> mode only. Input mode is not supported.
>
> +comment "Shift registers:"
> +
> +config GPIO_74X164
> + tristate "74x164 serial-in/parallel-out 8-bits shift register"
> + 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.
> +
> endif
> 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/74x164.h b/include/linux/74x164.h
> new file mode 100644
> index 0000000..1705732
> --- /dev/null
> +++ b/include/linux/74x164.h
> @@ -0,0 +1,22 @@
> +/*
> + * 74x164 - Serial-in/parallel-out 8-bits shift register
> + *
> + * Copyright (C) 2010 Gabor Juhos <juhosg@...nwrt.org>
> + *
> + * 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.
> + */
> +
> +#ifndef __74X164_H
> +#define __74X164_H
> +
> +#define GEN_74X164_DRIVER_NAME "74x164"
> +
> +struct gen_74x164_platform_data {
> + unsigned gpio_base;
> + unsigned gpio_pin_data;
> + unsigned gpio_pin_clk;
> +};
> +
> +#endif /* __74x164_H */
--
Florian
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