Messages in this thread Patch in this message | | | From | Florian Fainelli <> | Subject | [PATCH v2] GPIO: add support for 74HC164 serial-in/parallel-out 8-bit shift register | Date | Sun, 29 Aug 2010 17:37:30 +0200 |
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Hi,
Here is the second version of the patch: -- From: Miguel Gaio <miguel.gaio@efixo.com>
This patch adds support for generic 74HC164 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@efixo.com> Signed-off-by: Juhos Gabor <juhosg@openwrt.org> Signed-off-by: Florian Fainelli <florian@openwrt.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
diff --git a/drivers/gpio/74hc164.c b/drivers/gpio/74hc164.c new file mode 100644 index 0000000..fa63215 --- /dev/null +++ b/drivers/gpio/74hc164.c @@ -0,0 +1,228 @@ +/* + * 74HC164 - Serial-in/parallel-out 8-bits shift register GPIO driver + * + * Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org> + * Copyright (C) 2010 Miguel Gaio <miguel.gaio@efixo.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 74HC164 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/74hc164.h> + +#define GEN_74HC164_NUM_GPIOS 8 + +struct gen_74hc164_chip { + struct device *parent; + struct gpio_chip gpio_chip; + struct mutex lock; + long mask; +}; + +static void gen_74hc164_set_value(struct gpio_chip *, unsigned, int); + +static struct gen_74hc164_chip *gpio_to_chip(struct gpio_chip *gc) +{ + return container_of(gc, struct gen_74hc164_chip, gpio_chip); +} + +static int gen_74hc164_direction_input(struct gpio_chip *gc, unsigned offset) +{ + WARN_ON(1); + return -EINVAL; +} + +static int gen_74hc164_direction_output(struct gpio_chip *gc, + unsigned offset, int val) +{ + gen_74hc164_set_value(gc, offset, val); + return 0; +} + +static int gen_74hc164_get_value(struct gpio_chip *gc, unsigned offset) +{ + struct gen_74hc164_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_74hc164_set_value(struct gpio_chip *gc, + unsigned offset, int val) +{ + struct gen_74hc164_chip *chip; + struct gen_74hc164_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_74hc164_probe(struct platform_device *pdev) +{ + struct gen_74hc164_platform_data *pdata; + struct gen_74hc164_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_74hc164_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_74hc164_direction_input; + gc->direction_output = gen_74hc164_direction_output; + gc->get = gen_74hc164_get_value; + gc->set = gen_74hc164_set_value; + gc->can_sleep = 1; + + gc->base = pdata->gpio_base; + gc->ngpio = GEN_74HC164_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_74hc164_remove(struct platform_device *pdev) +{ + struct gen_74hc164_chip *chip = platform_get_drvdata(pdev); + struct gen_74hc164_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_74hc164_driver = { + .probe = gen_74hc164_probe, + .remove = __devexit_p(gen_74hc164_remove), + .driver = { + .name = GEN_74HC164_DRIVER_NAME, + .owner = THIS_MODULE, + }, +}; + +static int __init gen_74hc164_init(void) +{ + return platform_driver_register(&gen_74hc164_driver); +} +subsys_initcall(gen_74hc164_init); + +static void __exit gen_74hc164_exit(void) +{ + platform_driver_unregister(&gen_74hc164_driver); +} +module_exit(gen_74hc164_exit); + +MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>"); +MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>"); +MODULE_DESCRIPTION("GPIO expander driver for 74HC164 8-bits shift register"); +MODULE_LICENSE("GPL v2"); +MODULE_ALIAS("platform:" GEN_74HC164_DRIVER_NAME); diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig index 510aa20..ec27ab6 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_74HC164 + tristate "74HC164 serial-in/parallel-out 8-bit shift register" + help + Platform driver for 74HC164 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..2fcb2b8 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-$(CONFIG_GPIO_74HC164) += 74hc164.o obj-$(CONFIG_GPIO_PCA953X) += pca953x.o obj-$(CONFIG_GPIO_PCF857X) += pcf857x.o obj-$(CONFIG_GPIO_PL061) += pl061.o diff --git a/include/linux/74hc164.h b/include/linux/74hc164.h new file mode 100644 index 0000000..dae3d46 --- /dev/null +++ b/include/linux/74hc164.h @@ -0,0 +1,22 @@ +/* + * 74HC164 - Serial-in/parallel-out 8-bits shift register + * + * Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.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 __74HC164_H +#define __74HC164_H + +#define GEN_74HC164_DRIVER_NAME "74hc164" + +struct gen_74hc164_platform_data { + unsigned gpio_base; + unsigned gpio_pin_data; + unsigned gpio_pin_clk; +}; + +#endif /* __74HC164_H */
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