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Date: Wed, 1 Sep 2010 11:37:31 +0200
From: Florian Fainelli <florian@...nwrt.org>
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: [PATCH v4] GPIO: add support for 74x164 serial-in/parallel-out 8-bit shift register
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
diff --git a/drivers/gpio/74x164.c b/drivers/gpio/74x164.c
new file mode 100644
index 0000000..62e44b7
--- /dev/null
+++ b/drivers/gpio/74x164.c
@@ -0,0 +1,231 @@
+/*
+ * 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/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 32
+
+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 = pdata->ngpio - 1; i >= 0; --i) {
+ gpio_set_value(pdata->gpio_pin_data,
+ test_bit(i, &mask));
+ 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;
+ }
+
+ if (pdata->ngpio > GEN_74X164_NUM_GPIOS) {
+ dev_err(&pdev->dev, "invalid gpio count %u\n", pdata->ngpio);
+ 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 = pdata->ngpio;
+ 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..b58b159
--- /dev/null
+++ b/include/linux/74x164.h
@@ -0,0 +1,23 @@
+/*
+ * 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 ngpio;
+ unsigned gpio_pin_data;
+ unsigned gpio_pin_clk;
+};
+
+#endif /* __74x164_H */
--
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