gpio: add support for 74x164 serial-in/parallel-out 8-bit shift register

Add support for generic 74x164 serial-in/parallel-out 8-bits shift
register.  This driver can be used as a GPIO output expander.

[akpm@linux-foundation.org: remove unused local `refresh']
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/gpio/74x164.c b/drivers/gpio/74x164.c
new file mode 100644 (file)
index 0000000..d91ff4c
--- /dev/null
+++ b/drivers/gpio/74x164.c
@@ -0,0 +1,182 @@
+/*
+ *  74Hx164 - Generic 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.
+ */
+
+#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);
+
+       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@openwrt.org>");
+MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.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 e47ef94..bc7b0fc 100644 (file)
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -344,6 +344,14 @@ 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 3ff0651..0c23a4d 100644 (file)
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -18,6 +18,7 @@ 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 (file)
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