iio: stx104: Add GPIO support for the Apex Embedded Systems STX104

The Apex Embedded Systems STX104 device features eight lines of digital
I/O (four digital inputs and four digital outputs). This patch adds GPIO
support for these eight lines of digital I/O via GPIOLIB.

Cc: Alexandre Courbot <gnurou@gmail.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 61d5008..b3feb0b 100644 (file)
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -246,13 +246,14 @@ config MCP4922
          will be called mcp4922.
 
 config STX104
-       tristate "Apex Embedded Systems STX104 DAC driver"
+       tristate "Apex Embedded Systems STX104 driver"
        depends on ISA
+       select GPIOLIB
        help
-         Say yes here to build support for the 2-channel DAC on the Apex
-         Embedded Systems STX104 integrated analog PC/104 card. The base port
-         addresses for the devices may be configured via the "base" module
-         parameter array.
+         Say yes here to build support for the 2-channel DAC and GPIO on the
+         Apex Embedded Systems STX104 integrated analog PC/104 card. The base
+         port addresses for the devices may be configured via the base array
+         module parameter.
 
 config VF610_DAC
        tristate "Vybrid vf610 DAC driver"

diff --git a/drivers/iio/dac/stx104.c b/drivers/iio/dac/stx104.c
index 174f4b7..e0f31a1 100644 (file)
--- a/drivers/iio/dac/stx104.c
+++ b/drivers/iio/dac/stx104.c
@@ -14,6 +14,7 @@
 #include <linux/bitops.h>
 #include <linux/device.h>
 #include <linux/errno.h>
+#include <linux/gpio/driver.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/types.h>
 #include <linux/io.h>
@@ -21,6 +22,7 @@
 #include <linux/isa.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
+#include <linux/spinlock.h>
 
 #define STX104_NUM_CHAN 2
 
@@ -56,6 +58,20 @@ struct stx104_iio {
        unsigned base;
 };
 
+/**
+ * struct stx104_gpio - GPIO device private data structure
+ * @chip:      instance of the gpio_chip
+ * @lock:      synchronization lock to prevent I/O race conditions
+ * @base:      base port address of the GPIO device
+ * @out_state: output bits state
+ */
+struct stx104_gpio {
+       struct gpio_chip chip;
+       spinlock_t lock;
+       unsigned int base;
+       unsigned int out_state;
+};
+
 static int stx104_read_raw(struct iio_dev *indio_dev,
        struct iio_chan_spec const *chan, int *val, int *val2, long mask)
 {
@@ -95,15 +111,81 @@ static const struct iio_chan_spec stx104_channels[STX104_NUM_CHAN] = {
        STX104_CHAN(1)
 };
 
+static int stx104_gpio_get_direction(struct gpio_chip *chip,
+       unsigned int offset)
+{
+       if (offset < 4)
+               return 1;
+
+       return 0;
+}
+
+static int stx104_gpio_direction_input(struct gpio_chip *chip,
+       unsigned int offset)
+{
+       if (offset >= 4)
+               return -EINVAL;
+
+       return 0;
+}
+
+static int stx104_gpio_direction_output(struct gpio_chip *chip,
+       unsigned int offset, int value)
+{
+       if (offset < 4)
+               return -EINVAL;
+
+       chip->set(chip, offset, value);
+       return 0;
+}
+
+static int stx104_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+       struct stx104_gpio *const stx104gpio = gpiochip_get_data(chip);
+
+       if (offset >= 4)
+               return -EINVAL;
+
+       return !!(inb(stx104gpio->base) & BIT(offset));
+}
+
+static void stx104_gpio_set(struct gpio_chip *chip, unsigned int offset,
+       int value)
+{
+       struct stx104_gpio *const stx104gpio = gpiochip_get_data(chip);
+       const unsigned int mask = BIT(offset) >> 4;
+       unsigned long flags;
+
+       if (offset < 4)
+               return;
+
+       spin_lock_irqsave(&stx104gpio->lock, flags);
+
+       if (value)
+               stx104gpio->out_state |= mask;
+       else
+               stx104gpio->out_state &= ~mask;
+
+       outb(stx104gpio->out_state, stx104gpio->base);
+
+       spin_unlock_irqrestore(&stx104gpio->lock, flags);
+}
+
 static int stx104_probe(struct device *dev, unsigned int id)
 {
        struct iio_dev *indio_dev;
        struct stx104_iio *priv;
+       struct stx104_gpio *stx104gpio;
+       int err;
 
        indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
        if (!indio_dev)
                return -ENOMEM;
 
+       stx104gpio = devm_kzalloc(dev, sizeof(*stx104gpio), GFP_KERNEL);
+       if (!stx104gpio)
+               return -ENOMEM;
+
        if (!devm_request_region(dev, base[id], STX104_EXTENT,
                dev_name(dev))) {
                dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
@@ -124,14 +206,53 @@ static int stx104_probe(struct device *dev, unsigned int id)
        outw(0, base[id] + 4);
        outw(0, base[id] + 6);
 
-       return devm_iio_device_register(dev, indio_dev);
+       err = devm_iio_device_register(dev, indio_dev);
+       if (err) {
+               dev_err(dev, "IIO device registering failed (%d)\n", err);
+               return err;
+       }
+
+       stx104gpio->chip.label = dev_name(dev);
+       stx104gpio->chip.parent = dev;
+       stx104gpio->chip.owner = THIS_MODULE;
+       stx104gpio->chip.base = -1;
+       stx104gpio->chip.ngpio = 8;
+       stx104gpio->chip.get_direction = stx104_gpio_get_direction;
+       stx104gpio->chip.direction_input = stx104_gpio_direction_input;
+       stx104gpio->chip.direction_output = stx104_gpio_direction_output;
+       stx104gpio->chip.get = stx104_gpio_get;
+       stx104gpio->chip.set = stx104_gpio_set;
+       stx104gpio->base = base[id] + 3;
+       stx104gpio->out_state = 0x0;
+
+       spin_lock_init(&stx104gpio->lock);
+
+       dev_set_drvdata(dev, stx104gpio);
+
+       err = gpiochip_add_data(&stx104gpio->chip, stx104gpio);
+       if (err) {
+               dev_err(dev, "GPIO registering failed (%d)\n", err);
+               return err;
+       }
+
+       return 0;
+}
+
+static int stx104_remove(struct device *dev, unsigned int id)
+{
+       struct stx104_gpio *const stx104gpio = dev_get_drvdata(dev);
+
+       gpiochip_remove(&stx104gpio->chip);
+
+       return 0;
 }
 
 static struct isa_driver stx104_driver = {
        .probe = stx104_probe,
        .driver = {
                .name = "stx104"
-       }
+       },
+       .remove = stx104_remove
 };
 
 static void __exit stx104_exit(void)