[PATCH v5] gpio: Add GPIO support for the WinSystems WS16C48

[PATCH v5] gpio: Add GPIO support for the WinSystems WS16C48

[William Breathitt Gray]

The WinSystems WS16C48 device provides 48 lines of digital I/O. In
addition, the first 24 lines may be used for interrupt-handled edge
detection; rising edge detection and falling edge detection are
supported.

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 ws16c48_base module parameter. The interrupt line number for the
device may be configured via the ws16c48_irq module parameter.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
---
Changes in v5:
  - Allow sharing the IRQ

 MAINTAINERS                 |   6 +
 drivers/gpio/Kconfig        |   9 +
 drivers/gpio/Makefile       |   1 +
 drivers/gpio/gpio-ws16c48.c | 436 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 452 insertions(+)
 create mode 100644 drivers/gpio/gpio-ws16c48.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 4d7d83c..1cdb661 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11659,6 +11659,12 @@ M:	David Härdeman <david@hardeman.nu>
 S:	Maintained
 F:	drivers/media/rc/winbond-cir.c
 
+WINSYSTEMS WS16C48 GPIO DRIVER
+M:	William Breathitt Gray <vilhelm.gray@gmail.com>
+L:	linux-gpio@vger.kernel.org
+S:	Maintained
+F:	drivers/gpio/gpio-ws16c48.c
+
 WIMAX STACK
 M:	Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
 M:	linux-wimax@intel.com
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index cb212eb..b391139 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -577,6 +577,15 @@ config GPIO_TS5500
 	  blocks of the TS-5500: DIO1, DIO2 and the LCD port, and the TS-5600
 	  LCD port.
 
+config GPIO_WS16C48
+	tristate "WinSystems WS16C48 GPIO support"
+	select GPIOLIB_IRQCHIP
+	help
+	  Enables GPIO support for the WinSystems WS16C48. The base port address
+	  for the device may be configured via the ws16c48_base module
+	  parameter. The interrupt line number for the device may be configured
+	  via the ws16c48_irq module parameter.
+
 endmenu
 
 menu "I2C GPIO expanders"
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 548e9b5..bcb6cbe 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -112,6 +112,7 @@ obj-$(CONFIG_GPIO_VX855)	+= gpio-vx855.o
 obj-$(CONFIG_GPIO_WM831X)	+= gpio-wm831x.o
 obj-$(CONFIG_GPIO_WM8350)	+= gpio-wm8350.o
 obj-$(CONFIG_GPIO_WM8994)	+= gpio-wm8994.o
+obj-$(CONFIG_GPIO_WS16C48)	+= gpio-ws16c48.o
 obj-$(CONFIG_GPIO_XGENE)	+= gpio-xgene.o
 obj-$(CONFIG_GPIO_XGENE_SB)	+= gpio-xgene-sb.o
 obj-$(CONFIG_GPIO_XILINX)	+= gpio-xilinx.o
diff --git a/drivers/gpio/gpio-ws16c48.c b/drivers/gpio/gpio-ws16c48.c
new file mode 100644
index 0000000..9dd9479
--- /dev/null
+++ b/drivers/gpio/gpio-ws16c48.c
@@ -0,0 +1,436 @@
+/*
+ * GPIO driver for the WinSystems WS16C48
+ * 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 ws16c48_base;
+module_param(ws16c48_base, uint, 0);
+MODULE_PARM_DESC(ws16c48_base, "WinSystems WS16C48 base address");
+static unsigned ws16c48_irq;
+module_param(ws16c48_irq, uint, 0);
+MODULE_PARM_DESC(ws16c48_irq, "WinSystems WS16C48 interrupt line number");
+
+/**
+ * struct ws16c48_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
+ * @lock:	synchronization lock to prevent I/O race conditions
+ * @irq_mask:	I/O bits affected by interrupts
+ * @flow_mask:	IRQ flow type mask for the respective I/O bits
+ * @base:	base port address of the GPIO device
+ * @extent:	extent of port address region of the GPIO device
+ * @irq:	Interrupt line number
+ */
+struct ws16c48_gpio {
+	struct gpio_chip chip;
+	unsigned char io_state[6];
+	unsigned char out_state[6];
+	spinlock_t lock;
+	unsigned long irq_mask;
+	unsigned long flow_mask;
+	unsigned base;
+	unsigned extent;
+	unsigned irq;
+};
+
+static int ws16c48_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
+{
+	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
+	const unsigned port = offset / 8;
+	const unsigned mask = BIT(offset % 8);
+
+	return !!(ws16c48gpio->io_state[port] & mask);
+}
+
+static int ws16c48_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
+{
+	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
+	const unsigned port = offset / 8;
+	const unsigned mask = BIT(offset % 8);
+	unsigned long flags;
+
+	spin_lock_irqsave(&ws16c48gpio->lock, flags);
+
+	ws16c48gpio->io_state[port] |= mask;
+	ws16c48gpio->out_state[port] &= ~mask;
+	outb(ws16c48gpio->out_state[port], ws16c48gpio->base + port);
+
+	spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+
+	return 0;
+}
+
+static int ws16c48_gpio_direction_output(struct gpio_chip *chip,
+	unsigned offset, int value)
+{
+	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
+	const unsigned port = offset / 8;
+	const unsigned mask = BIT(offset % 8);
+	unsigned long flags;
+
+	spin_lock_irqsave(&ws16c48gpio->lock, flags);
+
+	ws16c48gpio->io_state[port] &= ~mask;
+	if (value)
+		ws16c48gpio->out_state[port] |= mask;
+	else
+		ws16c48gpio->out_state[port] &= ~mask;
+	outb(ws16c48gpio->out_state[port], ws16c48gpio->base + port);
+
+	spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+
+	return 0;
+}
+
+static int ws16c48_gpio_get(struct gpio_chip *chip, unsigned offset)
+{
+	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
+	const unsigned port = offset / 8;
+	const unsigned mask = BIT(offset % 8);
+	unsigned long flags;
+	unsigned port_state;
+
+	spin_lock_irqsave(&ws16c48gpio->lock, flags);
+
+	/* ensure that GPIO is set for input */
+	if (!(ws16c48gpio->io_state[port] & mask)) {
+		spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+		return -EINVAL;
+	}
+
+	port_state = inb(ws16c48gpio->base + port);
+
+	spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+
+	return !!(port_state & mask);
+}
+
+static void ws16c48_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
+	const unsigned port = offset / 8;
+	const unsigned mask = BIT(offset % 8);
+	unsigned long flags;
+
+	spin_lock_irqsave(&ws16c48gpio->lock, flags);
+
+	/* ensure that GPIO is set for output */
+	if (ws16c48gpio->io_state[port] & mask) {
+		spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+		return;
+	}
+
+	if (value)
+		ws16c48gpio->out_state[port] |= mask;
+	else
+		ws16c48gpio->out_state[port] &= ~mask;
+	outb(ws16c48gpio->out_state[port], ws16c48gpio->base + port);
+
+	spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+}
+
+static void ws16c48_irq_ack(struct irq_data *data)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
+	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
+	const unsigned long offset = irqd_to_hwirq(data);
+	const unsigned port = offset / 8;
+	const unsigned mask = BIT(offset % 8);
+	unsigned long flags;
+	unsigned port_state;
+
+	/* only the first 3 ports support interrupts */
+	if (port > 2)
+		return;
+
+	spin_lock_irqsave(&ws16c48gpio->lock, flags);
+
+	port_state = ws16c48gpio->irq_mask >> (8*port);
+
+	outb(0x80, ws16c48gpio->base + 7);
+	outb(port_state & ~mask, ws16c48gpio->base + 8 + port);
+	outb(port_state | mask, ws16c48gpio->base + 8 + port);
+	outb(0xC0, ws16c48gpio->base + 7);
+
+	spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+}
+
+static void ws16c48_irq_mask(struct irq_data *data)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
+	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
+	const unsigned long offset = irqd_to_hwirq(data);
+	const unsigned long mask = BIT(offset);
+	const unsigned port = offset / 8;
+	unsigned long flags;
+
+	/* only the first 3 ports support interrupts */
+	if (port > 2)
+		return;
+
+	spin_lock_irqsave(&ws16c48gpio->lock, flags);
+
+	ws16c48gpio->irq_mask &= ~mask;
+
+	outb(0x80, ws16c48gpio->base + 7);
+	outb(ws16c48gpio->irq_mask >> (8*port), ws16c48gpio->base + 8 + port);
+	outb(0xC0, ws16c48gpio->base + 7);
+
+	spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+}
+
+static void ws16c48_irq_unmask(struct irq_data *data)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
+	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
+	const unsigned long offset = irqd_to_hwirq(data);
+	const unsigned long mask = BIT(offset);
+	const unsigned port = offset / 8;
+	unsigned long flags;
+
+	/* only the first 3 ports support interrupts */
+	if (port > 2)
+		return;
+
+	spin_lock_irqsave(&ws16c48gpio->lock, flags);
+
+	ws16c48gpio->irq_mask |= mask;
+
+	outb(0x80, ws16c48gpio->base + 7);
+	outb(ws16c48gpio->irq_mask >> (8*port), ws16c48gpio->base + 8 + port);
+	outb(0xC0, ws16c48gpio->base + 7);
+
+	spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+}
+
+static int ws16c48_irq_set_type(struct irq_data *data, unsigned flow_type)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
+	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
+	const unsigned long offset = irqd_to_hwirq(data);
+	const unsigned long mask = BIT(offset);
+	const unsigned port = offset / 8;
+	unsigned long flags;
+
+	/* only the first 3 ports support interrupts */
+	if (port > 2)
+		return -EINVAL;
+
+	spin_lock_irqsave(&ws16c48gpio->lock, flags);
+
+	switch (flow_type) {
+	case IRQ_TYPE_NONE:
+		break;
+	case IRQ_TYPE_EDGE_RISING:
+		ws16c48gpio->flow_mask |= mask;
+		break;
+	case IRQ_TYPE_EDGE_FALLING:
+		ws16c48gpio->flow_mask &= ~mask;
+		break;
+	default:
+		spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+		return -EINVAL;
+	}
+
+	outb(0x40, ws16c48gpio->base + 7);
+	outb(ws16c48gpio->flow_mask >> (8*port), ws16c48gpio->base + 8 + port);
+	outb(0xC0, ws16c48gpio->base + 7);
+
+	spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+
+	return 0;
+}
+
+static struct irq_chip ws16c48_irqchip = {
+	.name = "ws16c48",
+	.irq_ack = ws16c48_irq_ack,
+	.irq_mask = ws16c48_irq_mask,
+	.irq_unmask = ws16c48_irq_unmask,
+	.irq_set_type = ws16c48_irq_set_type
+};
+
+static irqreturn_t ws16c48_irq_handler(int irq, void *dev_id)
+{
+	struct ws16c48_gpio *const ws16c48gpio = dev_id;
+	struct gpio_chip *const chip = &ws16c48gpio->chip;
+	unsigned long int_pending;
+	unsigned long port;
+	unsigned long int_id;
+	unsigned long gpio;
+
+	int_pending = inb(ws16c48gpio->base + 6) & 0x7;
+	if (!int_pending)
+		return IRQ_NONE;
+
+	/* loop until all pending interrupts are handled */
+	do {
+		for_each_set_bit(port, &int_pending, 3) {
+			int_id = inb(ws16c48gpio->base + 8 + port);
+			for_each_set_bit(gpio, &int_id, 8)
+				generic_handle_irq(irq_find_mapping(
+					chip->irqdomain, gpio + 8*port));
+		}
+
+		int_pending = inb(ws16c48gpio->base + 6) & 0x7;
+	} while (int_pending);
+
+	return IRQ_HANDLED;
+}
+
+static int __init ws16c48_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct ws16c48_gpio *ws16c48gpio;
+	const unsigned base = ws16c48_base;
+	const unsigned extent = 16;
+	const char *const name = dev_name(dev);
+	int err;
+	const unsigned irq = ws16c48_irq;
+
+	ws16c48gpio = devm_kzalloc(dev, sizeof(*ws16c48gpio), GFP_KERNEL);
+	if (!ws16c48gpio)
+		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;
+	}
+
+	ws16c48gpio->chip.label = name;
+	ws16c48gpio->chip.parent = dev;
+	ws16c48gpio->chip.owner = THIS_MODULE;
+	ws16c48gpio->chip.base = -1;
+	ws16c48gpio->chip.ngpio = 48;
+	ws16c48gpio->chip.get_direction = ws16c48_gpio_get_direction;
+	ws16c48gpio->chip.direction_input = ws16c48_gpio_direction_input;
+	ws16c48gpio->chip.direction_output = ws16c48_gpio_direction_output;
+	ws16c48gpio->chip.get = ws16c48_gpio_get;
+	ws16c48gpio->chip.set = ws16c48_gpio_set;
+	ws16c48gpio->base = base;
+	ws16c48gpio->extent = extent;
+	ws16c48gpio->irq = irq;
+
+	spin_lock_init(&ws16c48gpio->lock);
+
+	dev_set_drvdata(dev, ws16c48gpio);
+
+	err = gpiochip_add_data(&ws16c48gpio->chip, ws16c48gpio);
+	if (err) {
+		dev_err(dev, "GPIO registering failed (%d)\n", err);
+		goto err_gpio_register;
+	}
+
+	/* Disable IRQ by default */
+	outb(0x80, base + 7);
+	outb(0, base + 8);
+	outb(0, base + 9);
+	outb(0, base + 10);
+	outb(0xC0, base + 7);
+
+	err = gpiochip_irqchip_add(&ws16c48gpio->chip, &ws16c48_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, ws16c48_irq_handler, IRQF_SHARED, name,
+		ws16c48gpio);
+	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(&ws16c48gpio->chip);
+err_gpio_register:
+	release_region(base, extent);
+err_lock_io_port:
+	return err;
+}
+
+static int ws16c48_remove(struct platform_device *pdev)
+{
+	struct ws16c48_gpio *const ws16c48gpio = platform_get_drvdata(pdev);
+
+	free_irq(ws16c48gpio->irq, ws16c48gpio);
+	gpiochip_remove(&ws16c48gpio->chip);
+	release_region(ws16c48gpio->base, ws16c48gpio->extent);
+
+	return 0;
+}
+
+static struct platform_device *ws16c48_device;
+
+static struct platform_driver ws16c48_driver = {
+	.driver = {
+		.name = "ws16c48"
+	},
+	.remove = ws16c48_remove
+};
+
+static void __exit ws16c48_exit(void)
+{
+	platform_device_unregister(ws16c48_device);
+	platform_driver_unregister(&ws16c48_driver);
+}
+
+static int __init ws16c48_init(void)
+{
+	int err;
+
+	ws16c48_device = platform_device_alloc(ws16c48_driver.driver.name, -1);
+	if (!ws16c48_device)
+		return -ENOMEM;
+
+	err = platform_device_add(ws16c48_device);
+	if (err)
+		goto err_platform_device;
+
+	err = platform_driver_probe(&ws16c48_driver, ws16c48_probe);
+	if (err)
+		goto err_platform_driver;
+
+	return 0;
+
+err_platform_driver:
+	platform_device_del(ws16c48_device);
+err_platform_device:
+	platform_device_put(ws16c48_device);
+	return err;
+}
+
+module_init(ws16c48_init);
+module_exit(ws16c48_exit);
+
+MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
+MODULE_DESCRIPTION("WinSystems WS16C48 GPIO driver");
+MODULE_LICENSE("GPL");
-- 
2.4.10

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Re: [PATCH v5] gpio: Add GPIO support for the WinSystems WS16C48

[Linus Walleij]

On Wed, Jan 20, 2016 at 7:45 PM, William Breathitt Gray
<vilhelm.gray@gmail.com> wrote:

> The WinSystems WS16C48 device provides 48 lines of digital I/O. In
> addition, the first 24 lines may be used for interrupt-handled edge
> detection; rising edge detection and falling edge detection are
> supported.
>
> 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 ws16c48_base module parameter. The interrupt line number for the
> device may be configured via the ws16c48_irq module parameter.
>
> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
> ---
> Changes in v5:
>   - Allow sharing the IRQ

Patch applied.

Out of curiosity: what is your usecase for all these exotic
GPIO cards?

Yours,
Linus Walleij

Re: [PATCH v5] gpio: Add GPIO support for the WinSystems WS16C48

[William Breathitt Gray]

On Thu, Jan 28, 2016 at 09:47:43AM +0100, Linus Walleij wrote:
>Out of curiosity: what is your usecase for all these exotic
>GPIO cards?

My motivated mainly by philosophy. Despite their popularity in the
embedded systems industry, there isn't much support in the baseline
kernel for PC/104 and other cards. Typically, when a user purchases one
of these devices, they receive some general drivers which serve more as
proof that the device is working rather than as practical driver.

The user is lucky if they receive Linux drivers rather than just the
usual Windows drivers. Even if Linux drivers are provided, the drivers
are often written for ancient kernel versions (e.g. version 2.4), and
implement some custom character device structure rather than utilize the
Linux device model.

I'm writing these drivers to help bring support for these devices to the
baseline Linux kernel, in the hopes that it will be useful to someone,
and perhaps even motivate the companies to improve and share their own
Linux drivers.

William Breathitt Gray