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Message-Id: <201010182135.09506.florian@openwrt.org>
Date: Mon, 18 Oct 2010 21:35:07 +0200
From: Florian Fainelli <florian@...nwrt.org>
To: 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: [PATCH v5] 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
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);
+
+ __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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