gpio: Add GPIO support for the ACCES 104-DIO-48E

The ACCES 104-DIO-48E device provides 48 lines digital I/O via two
Programmable Peripheral Interface (PPI) chips of type 82C55. Bit C3 at
each 24-bit Group can be used as an external interrupt, triggered by a
rising edge.

This driver provides GPIO and IRQ support for these 48 channels of
digital I/O. The base port address for the device may be configured via
the dio_48e_base module parameter. The interrupt line number for the
device may be configured via the dio_48e_irq module parameter.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

4 files changed, 455 insertions, 0 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index 0ba80b692723..f043e957698d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -240,6 +240,12 @@ L:	lm-sensors@lm-sensors.org
 S:      Maintained
 F:      drivers/hwmon/abituguru3.c
 
+ACCES 104-DIO-48E GPIO DRIVER
+M:      William Breathitt Gray <vilhelm.gray@gmail.com>
+L:      linux-gpio@vger.kernel.org
+S:      Maintained
+F:      drivers/gpio/gpio-104-dio-48e.c
+
 ACCES 104-IDI-48 GPIO DRIVER
 M:      "William Breathitt Gray" <vilhelm.gray@gmail.com>
 L:      linux-gpio@vger.kernel.org
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index b5337f2e0eb4..5e317486a8cc 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -487,6 +487,15 @@ endmenu
 menu "Port-mapped I/O GPIO drivers"
         depends on X86 # Unconditional I/O space access
 
+config GPIO_104_DIO_48E
+        tristate "ACCES 104-DIO-48E GPIO support"
+        select GPIOLIB_IRQCHIP
+        help
+          Enables GPIO support for the ACCES 104-DIO-48E family. The base port
+          address for the device may be configured via the dio_48e_base module
+          parameter. The interrupt line number for the device may be configured
+          via the dio_48e_irq module parameter.
+
 config GPIO_104_IDIO_16
         tristate "ACCES 104-IDIO-16 GPIO support"
         select GPIOLIB_IRQCHIP
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 73121b1b3b94..d4cc4f3d3674 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -12,6 +12,7 @@ obj-$(CONFIG_GPIO_ACPI)		+= gpiolib-acpi.o
 # Device drivers. Generally keep list sorted alphabetically
 obj-$(CONFIG_GPIO_GENERIC)      += gpio-generic.o
 
+obj-$(CONFIG_GPIO_104_DIO_48E)  += gpio-104-dio-48e.o
 obj-$(CONFIG_GPIO_104_IDIO_16)  += gpio-104-idio-16.o
 obj-$(CONFIG_GPIO_104_IDI_48)   += gpio-104-idi-48.o
 obj-$(CONFIG_GPIO_74X164)       += gpio-74x164.o
diff --git a/drivers/gpio/gpio-104-dio-48e.c b/drivers/gpio/gpio-104-dio-48e.c
new file mode 100644
index 000000000000..279de392ac6c
--- /dev/null
+++ b/drivers/gpio/gpio-104-dio-48e.c
@@ -0,0 +1,439 @@
+/*
+ * GPIO driver for the ACCES 104-DIO-48E
+ * Copyright (C) 2016 William Breathitt Gray
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/gpio/driver.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/interrupt.h>
+#include <linux/irqdesc.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+
+static unsigned dio_48e_base;
+module_param(dio_48e_base, uint, 0);
+MODULE_PARM_DESC(dio_48e_base, "ACCES 104-DIO-48E base address");
+static unsigned dio_48e_irq;
+module_param(dio_48e_irq, uint, 0);
+MODULE_PARM_DESC(dio_48e_irq, "ACCES 104-DIO-48E interrupt line number");
+
+/**
+ * struct dio48e_gpio - GPIO device private data structure
+ * @chip:       instance of the gpio_chip
+ * @io_state:   bit I/O state (whether bit is set to input or output)
+ * @out_state:  output bits state
+ * @control:    Control registers state
+ * @lock:       synchronization lock to prevent I/O race conditions
+ * @base:       base port address of the GPIO device
+ * @extent:     extent of port address region of the GPIO device
+ * @irq:        Interrupt line number
+ * @irq_mask:   I/O bits affected by interrupts
+ */
+struct dio48e_gpio {
+        struct gpio_chip chip;
+        unsigned char io_state[6];
+        unsigned char out_state[6];
+        unsigned char control[2];
+        spinlock_t lock;
+        unsigned base;
+        unsigned extent;
+        unsigned irq;
+        unsigned char irq_mask;
+};
+
+static int dio48e_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
+{
+        struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
+        const unsigned port = offset / 8;
+        const unsigned mask = BIT(offset % 8);
+
+        return !!(dio48egpio->io_state[port] & mask);
+}
+
+static int dio48e_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
+{
+        struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
+        const unsigned io_port = offset / 8;
+        const unsigned control_port = io_port / 2;
+        const unsigned control_addr = dio48egpio->base + 3 + control_port*4;
+        unsigned long flags;
+        unsigned control;
+
+        spin_lock_irqsave(&dio48egpio->lock, flags);
+
+        /* Check if configuring Port C */
+        if (io_port == 2 || io_port == 5) {
+                /* Port C can be configured by nibble */
+                if (offset % 8 > 3) {
+                        dio48egpio->io_state[io_port] |= 0xF0;
+                        dio48egpio->control[control_port] |= BIT(3);
+                } else {
+                        dio48egpio->io_state[io_port] |= 0x0F;
+                        dio48egpio->control[control_port] |= BIT(0);
+                }
+        } else {
+                dio48egpio->io_state[io_port] |= 0xFF;
+                if (io_port == 0 || io_port == 3)
+                        dio48egpio->control[control_port] |= BIT(4);
+                else
+                        dio48egpio->control[control_port] |= BIT(1);
+        }
+
+        control = BIT(7) | dio48egpio->control[control_port];
+        outb(control, control_addr);
+        control &= ~BIT(7);
+        outb(control, control_addr);
+
+        spin_unlock_irqrestore(&dio48egpio->lock, flags);
+
+        return 0;
+}
+
+static int dio48e_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
+        int value)
+{
+        struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
+        const unsigned io_port = offset / 8;
+        const unsigned control_port = io_port / 2;
+        const unsigned mask = BIT(offset % 8);
+        const unsigned control_addr = dio48egpio->base + 3 + control_port*4;
+        const unsigned out_port = (io_port > 2) ? io_port + 1 : io_port;
+        unsigned long flags;
+        unsigned control;
+
+        spin_lock_irqsave(&dio48egpio->lock, flags);
+
+        /* Check if configuring Port C */
+        if (io_port == 2 || io_port == 5) {
+                /* Port C can be configured by nibble */
+                if (offset % 8 > 3) {
+                        dio48egpio->io_state[io_port] &= 0x0F;
+                        dio48egpio->control[control_port] &= ~BIT(3);
+                } else {
+                        dio48egpio->io_state[io_port] &= 0xF0;
+                        dio48egpio->control[control_port] &= ~BIT(0);
+                }
+        } else {
+                dio48egpio->io_state[io_port] &= 0x00;
+                if (io_port == 0 || io_port == 3)
+                        dio48egpio->control[control_port] &= ~BIT(4);
+                else
+                        dio48egpio->control[control_port] &= ~BIT(1);
+        }
+
+        if (value)
+                dio48egpio->out_state[io_port] |= mask;
+        else
+                dio48egpio->out_state[io_port] &= ~mask;
+
+        control = BIT(7) | dio48egpio->control[control_port];
+        outb(control, control_addr);
+
+        outb(dio48egpio->out_state[io_port], dio48egpio->base + out_port);
+
+        control &= ~BIT(7);
+        outb(control, control_addr);
+
+        spin_unlock_irqrestore(&dio48egpio->lock, flags);
+
+        return 0;
+}
+
+static int dio48e_gpio_get(struct gpio_chip *chip, unsigned offset)
+{
+        struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
+        const unsigned port = offset / 8;
+        const unsigned mask = BIT(offset % 8);
+        const unsigned in_port = (port > 2) ? port + 1 : port;
+        unsigned long flags;
+        unsigned port_state;
+
+        spin_lock_irqsave(&dio48egpio->lock, flags);
+
+        /* ensure that GPIO is set for input */
+        if (!(dio48egpio->io_state[port] & mask)) {
+                spin_unlock_irqrestore(&dio48egpio->lock, flags);
+                return -EINVAL;
+        }
+
+        port_state = inb(dio48egpio->base + in_port);
+
+        spin_unlock_irqrestore(&dio48egpio->lock, flags);
+
+        return !!(port_state & mask);
+}
+
+static void dio48e_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+        struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
+        const unsigned port = offset / 8;
+        const unsigned mask = BIT(offset % 8);
+        const unsigned out_port = (port > 2) ? port + 1 : port;
+        unsigned long flags;
+
+        spin_lock_irqsave(&dio48egpio->lock, flags);
+
+        if (value)
+                dio48egpio->out_state[port] |= mask;
+        else
+                dio48egpio->out_state[port] &= ~mask;
+
+        outb(dio48egpio->out_state[port], dio48egpio->base + out_port);
+
+        spin_unlock_irqrestore(&dio48egpio->lock, flags);
+}
+
+static void dio48e_irq_ack(struct irq_data *data)
+{
+}
+
+static void dio48e_irq_mask(struct irq_data *data)
+{
+        struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
+        struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
+        const unsigned long offset = irqd_to_hwirq(data);
+        unsigned long flags;
+
+        /* only bit 3 on each respective Port C supports interrupts */
+        if (offset != 19 && offset != 43)
+                return;
+
+        spin_lock_irqsave(&dio48egpio->lock, flags);
+
+        if (offset == 19)
+                dio48egpio->irq_mask &= ~BIT(0);
+        else
+                dio48egpio->irq_mask &= ~BIT(1);
+
+        if (!dio48egpio->irq_mask)
+                /* disable interrupts */
+                inb(dio48egpio->base + 0xB);
+
+        spin_unlock_irqrestore(&dio48egpio->lock, flags);
+}
+
+static void dio48e_irq_unmask(struct irq_data *data)
+{
+        struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
+        struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
+        const unsigned long offset = irqd_to_hwirq(data);
+        unsigned long flags;
+
+        /* only bit 3 on each respective Port C supports interrupts */
+        if (offset != 19 && offset != 43)
+                return;
+
+        spin_lock_irqsave(&dio48egpio->lock, flags);
+
+        if (!dio48egpio->irq_mask) {
+                /* enable interrupts */
+                outb(0x00, dio48egpio->base + 0xF);
+                outb(0x00, dio48egpio->base + 0xB);
+        }
+
+        if (offset == 19)
+                dio48egpio->irq_mask |= BIT(0);
+        else
+                dio48egpio->irq_mask |= BIT(1);
+
+        spin_unlock_irqrestore(&dio48egpio->lock, flags);
+}
+
+static int dio48e_irq_set_type(struct irq_data *data, unsigned flow_type)
+{
+        const unsigned long offset = irqd_to_hwirq(data);
+
+        /* only bit 3 on each respective Port C supports interrupts */
+        if (offset != 19 && offset != 43)
+                return -EINVAL;
+
+        if (flow_type != IRQ_TYPE_NONE && flow_type != IRQ_TYPE_EDGE_RISING)
+                return -EINVAL;
+
+        return 0;
+}
+
+static struct irq_chip dio48e_irqchip = {
+        .name = "104-dio-48e",
+        .irq_ack = dio48e_irq_ack,
+        .irq_mask = dio48e_irq_mask,
+        .irq_unmask = dio48e_irq_unmask,
+        .irq_set_type = dio48e_irq_set_type
+};
+
+static irqreturn_t dio48e_irq_handler(int irq, void *dev_id)
+{
+        struct dio48e_gpio *const dio48egpio = dev_id;
+        struct gpio_chip *const chip = &dio48egpio->chip;
+        const unsigned long irq_mask = dio48egpio->irq_mask;
+        unsigned long gpio;
+
+        for_each_set_bit(gpio, &irq_mask, 2)
+                generic_handle_irq(irq_find_mapping(chip->irqdomain,
+                        19 + gpio*24));
+
+        spin_lock(&dio48egpio->lock);
+
+        outb(0x00, dio48egpio->base + 0xF);
+
+        spin_unlock(&dio48egpio->lock);
+
+        return IRQ_HANDLED;
+}
+
+static int __init dio48e_probe(struct platform_device *pdev)
+{
+        struct device *dev = &pdev->dev;
+        struct dio48e_gpio *dio48egpio;
+        const unsigned base = dio_48e_base;
+        const unsigned extent = 16;
+        const char *const name = dev_name(dev);
+        int err;
+        const unsigned irq = dio_48e_irq;
+
+        dio48egpio = devm_kzalloc(dev, sizeof(*dio48egpio), GFP_KERNEL);
+        if (!dio48egpio)
+                return -ENOMEM;
+
+        if (!request_region(base, extent, name)) {
+                dev_err(dev, "Unable to lock %s port addresses (0x%X-0x%X)\n",
+                        name, base, base + extent);
+                err = -EBUSY;
+                goto err_lock_io_port;
+        }
+
+        dio48egpio->chip.label = name;
+        dio48egpio->chip.parent = dev;
+        dio48egpio->chip.owner = THIS_MODULE;
+        dio48egpio->chip.base = -1;
+        dio48egpio->chip.ngpio = 48;
+        dio48egpio->chip.get_direction = dio48e_gpio_get_direction;
+        dio48egpio->chip.direction_input = dio48e_gpio_direction_input;
+        dio48egpio->chip.direction_output = dio48e_gpio_direction_output;
+        dio48egpio->chip.get = dio48e_gpio_get;
+        dio48egpio->chip.set = dio48e_gpio_set;
+        dio48egpio->base = base;
+        dio48egpio->extent = extent;
+        dio48egpio->irq = irq;
+
+        spin_lock_init(&dio48egpio->lock);
+
+        dev_set_drvdata(dev, dio48egpio);
+
+        err = gpiochip_add_data(&dio48egpio->chip, dio48egpio);
+        if (err) {
+                dev_err(dev, "GPIO registering failed (%d)\n", err);
+                goto err_gpio_register;
+        }
+
+        /* initialize all GPIO as output */
+        outb(0x80, base + 3);
+        outb(0x00, base);
+        outb(0x00, base + 1);
+        outb(0x00, base + 2);
+        outb(0x00, base + 3);
+        outb(0x80, base + 7);
+        outb(0x00, base + 4);
+        outb(0x00, base + 5);
+        outb(0x00, base + 6);
+        outb(0x00, base + 7);
+
+        /* disable IRQ by default */
+        inb(base + 0xB);
+
+        err = gpiochip_irqchip_add(&dio48egpio->chip, &dio48e_irqchip, 0,
+                handle_edge_irq, IRQ_TYPE_NONE);
+        if (err) {
+                dev_err(dev, "Could not add irqchip (%d)\n", err);
+                goto err_gpiochip_irqchip_add;
+        }
+
+        err = request_irq(irq, dio48e_irq_handler, 0, name, dio48egpio);
+        if (err) {
+                dev_err(dev, "IRQ handler registering failed (%d)\n", err);
+                goto err_request_irq;
+        }
+
+        return 0;
+
+err_request_irq:
+err_gpiochip_irqchip_add:
+        gpiochip_remove(&dio48egpio->chip);
+err_gpio_register:
+        release_region(base, extent);
+err_lock_io_port:
+        return err;
+}
+
+static int dio48e_remove(struct platform_device *pdev)
+{
+        struct dio48e_gpio *const dio48egpio = platform_get_drvdata(pdev);
+
+        free_irq(dio48egpio->irq, dio48egpio);
+        gpiochip_remove(&dio48egpio->chip);
+        release_region(dio48egpio->base, dio48egpio->extent);
+
+        return 0;
+}
+
+static struct platform_device *dio48e_device;
+
+static struct platform_driver dio48e_driver = {
+        .driver = {
+                .name = "104-dio-48e"
+        },
+        .remove = dio48e_remove
+};
+
+static void __exit dio48e_exit(void)
+{
+        platform_device_unregister(dio48e_device);
+        platform_driver_unregister(&dio48e_driver);
+}
+
+static int __init dio48e_init(void)
+{
+        int err;
+
+        dio48e_device = platform_device_alloc(dio48e_driver.driver.name, -1);
+        if (!dio48e_device)
+                return -ENOMEM;
+
+        err = platform_device_add(dio48e_device);
+        if (err)
+                goto err_platform_device;
+
+        err = platform_driver_probe(&dio48e_driver, dio48e_probe);
+        if (err)
+                goto err_platform_driver;
+
+        return 0;
+
+err_platform_driver:
+        platform_device_del(dio48e_device);
+err_platform_device:
+        platform_device_put(dio48e_device);
+        return err;
+}
+
+module_init(dio48e_init);
+module_exit(dio48e_exit);
+
+MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
+MODULE_DESCRIPTION("ACCES 104-DIO-48E GPIO driver");
+MODULE_LICENSE("GPL");