gpio: Add GPIO support for the ACCES PCIe-IDIO-24 family

The ACCES PCIe-IDIO-24 device provides 56 lines of digital I/O (24 lines
of optically-isolated non-polarized digital inputs for AC and DC control
signals, 24 lines of isolated solid state FET digital outputs, and 8
non-isolated TTL/CMOS compatible programmable I/O). An interrupt is
generated when any of the inputs change state (low to high or high to
low).

Input filter control is not supported by this driver, and input filters
are deactivated by this driver. These devices are capable of
get_multiple and set_multiple functionality, but these functions have
not yet been implemented for this driver. Change-Of-State (COS)
detection functionality may be configured to fire interrupts on
exclusively rising/falling edges, but this driver currently only
implements COS detection for either both edges or none.

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

4 files changed, 464 insertions, 0 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index 89e2acf95981..57811dfb3416 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -270,6 +270,12 @@ L:	linux-gpio@vger.kernel.org
 S:	Maintained
 F:	drivers/gpio/gpio-pci-idio-16.c
 
+ACCES PCIe-IDIO-24 GPIO DRIVER
+M:	William Breathitt Gray <vilhelm.gray@gmail.com>
+L:	linux-gpio@vger.kernel.org
+S:	Maintained
+F:	drivers/gpio/gpio-pcie-idio-24.c
+
 ACENIC DRIVER
 M:	Jes Sorensen <jes@trained-monkey.org>
 L:	linux-acenic@sunsite.dk
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 8c4018855c3b..440af077cc76 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -1244,6 +1244,16 @@ config GPIO_PCI_IDIO_16
 	  low). Input filter control is not supported by this driver, and the
 	  input filters are deactivated by this driver.
 
+config GPIO_PCIE_IDIO_24
+	tristate "ACCES PCIe-IDIO-24 GPIO support"
+	select GPIOLIB_IRQCHIP
+	help
+	  Enables GPIO support for the ACCES PCIe-IDIO-24 family (PCIe-IDIO-24,
+	  PCIe-IDI-24, PCIe-IDO-24, PCIe-IDIO-12). An interrupt is generated
+	  when any of the inputs change state (low to high or high to low).
+	  Input filter control is not supported by this driver, and the input
+	  filters are deactivated by this driver.
+
 config GPIO_RDC321X
 	tristate "RDC R-321x GPIO support"
 	select MFD_CORE
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index ff3d36d0a443..cccb0d40846c 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -95,6 +95,7 @@ obj-$(CONFIG_GPIO_PCA953X)	+= gpio-pca953x.o
 obj-$(CONFIG_GPIO_PCF857X)	+= gpio-pcf857x.o
 obj-$(CONFIG_GPIO_PCH)		+= gpio-pch.o
 obj-$(CONFIG_GPIO_PCI_IDIO_16)	+= gpio-pci-idio-16.o
+obj-$(CONFIG_GPIO_PCIE_IDIO_24)	+= gpio-pcie-idio-24.o
 obj-$(CONFIG_GPIO_PISOSR)	+= gpio-pisosr.o
 obj-$(CONFIG_GPIO_PL061)	+= gpio-pl061.o
 obj-$(CONFIG_GPIO_PXA)		+= gpio-pxa.o
diff --git a/drivers/gpio/gpio-pcie-idio-24.c b/drivers/gpio/gpio-pcie-idio-24.c
new file mode 100644
index 000000000000..f666e2e69074
--- /dev/null
+++ b/drivers/gpio/gpio-pcie-idio-24.c
@@ -0,0 +1,447 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * GPIO driver for the ACCES PCIe-IDIO-24 family
+ * Copyright (C) 2018 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.
+ *
+ * This driver supports the following ACCES devices: PCIe-IDIO-24,
+ * PCIe-IDI-24, PCIe-IDO-24, and PCIe-IDIO-12.
+ */
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/gpio/driver.h>
+#include <linux/interrupt.h>
+#include <linux/irqdesc.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
+/**
+ * struct idio_24_gpio_reg - GPIO device registers structure
+ * @out0_7:	Read: FET Outputs 0-7
+ *		Write: FET Outputs 0-7
+ * @out8_15:	Read: FET Outputs 8-15
+ *		Write: FET Outputs 8-15
+ * @out16_23:	Read: FET Outputs 16-23
+ *		Write: FET Outputs 16-23
+ * @ttl_out0_7:	Read: TTL/CMOS Outputs 0-7
+ *		Write: TTL/CMOS Outputs 0-7
+ * @in0_7:	Read: Isolated Inputs 0-7
+ *		Write: Reserved
+ * @in8_15:	Read: Isolated Inputs 8-15
+ *		Write: Reserved
+ * @in16_23:	Read: Isolated Inputs 16-23
+ *		Write: Reserved
+ * @ttl_in0_7:	Read: TTL/CMOS Inputs 0-7
+ *		Write: Reserved
+ * @cos0_7:	Read: COS Status Inputs 0-7
+ *		Write: COS Clear Inputs 0-7
+ * @cos8_15:	Read: COS Status Inputs 8-15
+ *		Write: COS Clear Inputs 8-15
+ * @cos16_23:	Read: COS Status Inputs 16-23
+ *		Write: COS Clear Inputs 16-23
+ * @cos_ttl0_7:	Read: COS Status TTL/CMOS 0-7
+ *		Write: COS Clear TTL/CMOS 0-7
+ * @ctl:	Read: Control Register
+ *		Write: Control Register
+ * @reserved:	Read: Reserved
+ *		Write: Reserved
+ * @cos_enable:	Read: COS Enable
+ *		Write: COS Enable
+ * @soft_reset:	Read: IRQ Output Pin Status
+ *		Write: Software Board Reset
+ */
+struct idio_24_gpio_reg {
+	u8 out0_7;
+	u8 out8_15;
+	u8 out16_23;
+	u8 ttl_out0_7;
+	u8 in0_7;
+	u8 in8_15;
+	u8 in16_23;
+	u8 ttl_in0_7;
+	u8 cos0_7;
+	u8 cos8_15;
+	u8 cos16_23;
+	u8 cos_ttl0_7;
+	u8 ctl;
+	u8 reserved;
+	u8 cos_enable;
+	u8 soft_reset;
+};
+
+/**
+ * struct idio_24_gpio - GPIO device private data structure
+ * @chip:	instance of the gpio_chip
+ * @lock:	synchronization lock to prevent I/O race conditions
+ * @reg:	I/O address offset for the GPIO device registers
+ * @irq_mask:	I/O bits affected by interrupts
+ */
+struct idio_24_gpio {
+	struct gpio_chip chip;
+	raw_spinlock_t lock;
+	struct idio_24_gpio_reg __iomem *reg;
+	unsigned long irq_mask;
+};
+
+static int idio_24_gpio_get_direction(struct gpio_chip *chip,
+	unsigned int offset)
+{
+	struct idio_24_gpio *const idio24gpio = gpiochip_get_data(chip);
+	const unsigned long out_mode_mask = BIT(1);
+
+	/* FET Outputs */
+	if (offset < 24)
+		return 0;
+
+	/* Isolated Inputs */
+	if (offset < 48)
+		return 1;
+
+	/* TTL/CMOS I/O */
+	/* OUT MODE = 1 when TTL/CMOS Output Mode is set */
+	return !(ioread8(&idio24gpio->reg->ctl) & out_mode_mask);
+}
+
+static int idio_24_gpio_direction_input(struct gpio_chip *chip,
+	unsigned int offset)
+{
+	struct idio_24_gpio *const idio24gpio = gpiochip_get_data(chip);
+	unsigned long flags;
+	unsigned int ctl_state;
+	const unsigned long out_mode_mask = BIT(1);
+
+	/* TTL/CMOS I/O */
+	if (offset > 47) {
+		raw_spin_lock_irqsave(&idio24gpio->lock, flags);
+
+		/* Clear TTL/CMOS Output Mode */
+		ctl_state = ioread8(&idio24gpio->reg->ctl) & ~out_mode_mask;
+		iowrite8(ctl_state, &idio24gpio->reg->ctl);
+
+		raw_spin_unlock_irqrestore(&idio24gpio->lock, flags);
+	}
+
+	return 0;
+}
+
+static int idio_24_gpio_direction_output(struct gpio_chip *chip,
+	unsigned int offset, int value)
+{
+	struct idio_24_gpio *const idio24gpio = gpiochip_get_data(chip);
+	unsigned long flags;
+	unsigned int ctl_state;
+	const unsigned long out_mode_mask = BIT(1);
+
+	/* TTL/CMOS I/O */
+	if (offset > 47) {
+		raw_spin_lock_irqsave(&idio24gpio->lock, flags);
+
+		/* Set TTL/CMOS Output Mode */
+		ctl_state = ioread8(&idio24gpio->reg->ctl) | out_mode_mask;
+		iowrite8(ctl_state, &idio24gpio->reg->ctl);
+
+		raw_spin_unlock_irqrestore(&idio24gpio->lock, flags);
+	}
+
+	chip->set(chip, offset, value);
+	return 0;
+}
+
+static int idio_24_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+	struct idio_24_gpio *const idio24gpio = gpiochip_get_data(chip);
+	const unsigned long offset_mask = BIT(offset % 8);
+	const unsigned long out_mode_mask = BIT(1);
+
+	/* FET Outputs */
+	if (offset < 8)
+		return !!(ioread8(&idio24gpio->reg->out0_7) & offset_mask);
+
+	if (offset < 16)
+		return !!(ioread8(&idio24gpio->reg->out8_15) & offset_mask);
+
+	if (offset < 24)
+		return !!(ioread8(&idio24gpio->reg->out16_23) & offset_mask);
+
+	/* Isolated Inputs */
+	if (offset < 32)
+		return !!(ioread8(&idio24gpio->reg->in0_7) & offset_mask);
+
+	if (offset < 40)
+		return !!(ioread8(&idio24gpio->reg->in8_15) & offset_mask);
+
+	if (offset < 48)
+		return !!(ioread8(&idio24gpio->reg->in16_23) & offset_mask);
+
+	/* TTL/CMOS Outputs */
+	if (ioread8(&idio24gpio->reg->ctl) & out_mode_mask)
+		return !!(ioread8(&idio24gpio->reg->ttl_out0_7) & offset_mask);
+
+	/* TTL/CMOS Inputs */
+	return !!(ioread8(&idio24gpio->reg->ttl_in0_7) & offset_mask);
+}
+
+static void idio_24_gpio_set(struct gpio_chip *chip, unsigned int offset,
+	int value)
+{
+	struct idio_24_gpio *const idio24gpio = gpiochip_get_data(chip);
+	const unsigned long out_mode_mask = BIT(1);
+	void __iomem *base;
+	const unsigned int mask = BIT(offset % 8);
+	unsigned long flags;
+	unsigned int out_state;
+
+	/* Isolated Inputs */
+	if (offset > 23 && offset < 48)
+		return;
+
+	/* TTL/CMOS Inputs */
+	if (offset > 47 && !(ioread8(&idio24gpio->reg->ctl) & out_mode_mask))
+		return;
+
+	/* TTL/CMOS Outputs */
+	if (offset > 47)
+		base = &idio24gpio->reg->ttl_out0_7;
+	/* FET Outputs */
+	else if (offset > 15)
+		base = &idio24gpio->reg->out16_23;
+	else if (offset > 7)
+		base = &idio24gpio->reg->out8_15;
+	else
+		base = &idio24gpio->reg->out0_7;
+
+	raw_spin_lock_irqsave(&idio24gpio->lock, flags);
+
+	if (value)
+		out_state = ioread8(base) | mask;
+	else
+		out_state = ioread8(base) & ~mask;
+
+	iowrite8(out_state, base);
+
+	raw_spin_unlock_irqrestore(&idio24gpio->lock, flags);
+}
+
+static void idio_24_irq_ack(struct irq_data *data)
+{
+}
+
+static void idio_24_irq_mask(struct irq_data *data)
+{
+	struct gpio_chip *const chip = irq_data_get_irq_chip_data(data);
+	struct idio_24_gpio *const idio24gpio = gpiochip_get_data(chip);
+	unsigned long flags;
+	const unsigned long bit_offset = irqd_to_hwirq(data) - 24;
+	unsigned char new_irq_mask;
+	const unsigned long bank_offset = bit_offset/8 * 8;
+	unsigned char cos_enable_state;
+
+	raw_spin_lock_irqsave(&idio24gpio->lock, flags);
+
+	idio24gpio->irq_mask &= BIT(bit_offset);
+	new_irq_mask = idio24gpio->irq_mask >> bank_offset;
+
+	if (!new_irq_mask) {
+		cos_enable_state = ioread8(&idio24gpio->reg->cos_enable);
+
+		/* Disable Rising Edge detection */
+		cos_enable_state &= ~BIT(bank_offset);
+		/* Disable Falling Edge detection */
+		cos_enable_state &= ~BIT(bank_offset + 4);
+
+		iowrite8(cos_enable_state, &idio24gpio->reg->cos_enable);
+	}
+
+	raw_spin_unlock_irqrestore(&idio24gpio->lock, flags);
+}
+
+static void idio_24_irq_unmask(struct irq_data *data)
+{
+	struct gpio_chip *const chip = irq_data_get_irq_chip_data(data);
+	struct idio_24_gpio *const idio24gpio = gpiochip_get_data(chip);
+	unsigned long flags;
+	unsigned char prev_irq_mask;
+	const unsigned long bit_offset = irqd_to_hwirq(data) - 24;
+	const unsigned long bank_offset = bit_offset/8 * 8;
+	unsigned char cos_enable_state;
+
+	raw_spin_lock_irqsave(&idio24gpio->lock, flags);
+
+	prev_irq_mask = idio24gpio->irq_mask >> bank_offset;
+	idio24gpio->irq_mask |= BIT(bit_offset);
+
+	if (!prev_irq_mask) {
+		cos_enable_state = ioread8(&idio24gpio->reg->cos_enable);
+
+		/* Enable Rising Edge detection */
+		cos_enable_state |= BIT(bank_offset);
+		/* Enable Falling Edge detection */
+		cos_enable_state |= BIT(bank_offset + 4);
+
+		iowrite8(cos_enable_state, &idio24gpio->reg->cos_enable);
+	}
+
+	raw_spin_unlock_irqrestore(&idio24gpio->lock, flags);
+}
+
+static int idio_24_irq_set_type(struct irq_data *data, unsigned int flow_type)
+{
+	/* The only valid irq types are none and both-edges */
+	if (flow_type != IRQ_TYPE_NONE &&
+		(flow_type & IRQ_TYPE_EDGE_BOTH) != IRQ_TYPE_EDGE_BOTH)
+		return -EINVAL;
+
+	return 0;
+}
+
+static struct irq_chip idio_24_irqchip = {
+	.name = "pcie-idio-24",
+	.irq_ack = idio_24_irq_ack,
+	.irq_mask = idio_24_irq_mask,
+	.irq_unmask = idio_24_irq_unmask,
+	.irq_set_type = idio_24_irq_set_type
+};
+
+static irqreturn_t idio_24_irq_handler(int irq, void *dev_id)
+{
+	struct idio_24_gpio *const idio24gpio = dev_id;
+	unsigned long irq_status;
+	struct gpio_chip *const chip = &idio24gpio->chip;
+	unsigned long irq_mask;
+	int gpio;
+
+	raw_spin_lock(&idio24gpio->lock);
+
+	/* Read Change-Of-State status */
+	irq_status = ioread32(&idio24gpio->reg->cos0_7);
+
+	raw_spin_unlock(&idio24gpio->lock);
+
+	/* Make sure our device generated IRQ */
+	if (!irq_status)
+		return IRQ_NONE;
+
+	/* Handle only unmasked IRQ */
+	irq_mask = idio24gpio->irq_mask & irq_status;
+
+	for_each_set_bit(gpio, &irq_mask, chip->ngpio - 24)
+		generic_handle_irq(irq_find_mapping(chip->irq.domain,
+			gpio + 24));
+
+	raw_spin_lock(&idio24gpio->lock);
+
+	/* Clear Change-Of-State status */
+	iowrite32(irq_status, &idio24gpio->reg->cos0_7);
+
+	raw_spin_unlock(&idio24gpio->lock);
+
+	return IRQ_HANDLED;
+}
+
+#define IDIO_24_NGPIO 56
+static const char *idio_24_names[IDIO_24_NGPIO] = {
+	"OUT0", "OUT1", "OUT2", "OUT3", "OUT4", "OUT5", "OUT6", "OUT7",
+	"OUT8", "OUT9", "OUT10", "OUT11", "OUT12", "OUT13", "OUT14", "OUT15",
+	"OUT16", "OUT17", "OUT18", "OUT19", "OUT20", "OUT21", "OUT22", "OUT23",
+	"IIN0", "IIN1", "IIN2", "IIN3", "IIN4", "IIN5", "IIN6", "IIN7",
+	"IIN8", "IIN9", "IIN10", "IIN11", "IIN12", "IIN13", "IIN14", "IIN15",
+	"IIN16", "IIN17", "IIN18", "IIN19", "IIN20", "IIN21", "IIN22", "IIN23",
+	"TTL0", "TTL1", "TTL2", "TTL3", "TTL4", "TTL5", "TTL6", "TTL7"
+};
+
+static int idio_24_probe(struct pci_dev *pdev, const struct pci_device_id *id)
+{
+	struct device *const dev = &pdev->dev;
+	struct idio_24_gpio *idio24gpio;
+	int err;
+	const size_t pci_bar_index = 2;
+	const char *const name = pci_name(pdev);
+
+	idio24gpio = devm_kzalloc(dev, sizeof(*idio24gpio), GFP_KERNEL);
+	if (!idio24gpio)
+		return -ENOMEM;
+
+	err = pcim_enable_device(pdev);
+	if (err) {
+		dev_err(dev, "Failed to enable PCI device (%d)\n", err);
+		return err;
+	}
+
+	err = pcim_iomap_regions(pdev, BIT(pci_bar_index), name);
+	if (err) {
+		dev_err(dev, "Unable to map PCI I/O addresses (%d)\n", err);
+		return err;
+	}
+
+	idio24gpio->reg = pcim_iomap_table(pdev)[pci_bar_index];
+
+	idio24gpio->chip.label = name;
+	idio24gpio->chip.parent = dev;
+	idio24gpio->chip.owner = THIS_MODULE;
+	idio24gpio->chip.base = -1;
+	idio24gpio->chip.ngpio = IDIO_24_NGPIO;
+	idio24gpio->chip.names = idio_24_names;
+	idio24gpio->chip.get_direction = idio_24_gpio_get_direction;
+	idio24gpio->chip.direction_input = idio_24_gpio_direction_input;
+	idio24gpio->chip.direction_output = idio_24_gpio_direction_output;
+	idio24gpio->chip.get = idio_24_gpio_get;
+	idio24gpio->chip.set = idio_24_gpio_set;
+
+	raw_spin_lock_init(&idio24gpio->lock);
+
+	/* Software board reset */
+	iowrite8(0, &idio24gpio->reg->soft_reset);
+
+	err = devm_gpiochip_add_data(dev, &idio24gpio->chip, idio24gpio);
+	if (err) {
+		dev_err(dev, "GPIO registering failed (%d)\n", err);
+		return err;
+	}
+
+	err = gpiochip_irqchip_add(&idio24gpio->chip, &idio_24_irqchip, 0,
+		handle_edge_irq, IRQ_TYPE_NONE);
+	if (err) {
+		dev_err(dev, "Could not add irqchip (%d)\n", err);
+		return err;
+	}
+
+	err = devm_request_irq(dev, pdev->irq, idio_24_irq_handler, IRQF_SHARED,
+		name, idio24gpio);
+	if (err) {
+		dev_err(dev, "IRQ handler registering failed (%d)\n", err);
+		return err;
+	}
+
+	return 0;
+}
+
+static const struct pci_device_id idio_24_pci_dev_id[] = {
+	{ PCI_DEVICE(0x494F, 0x0FD0) }, { PCI_DEVICE(0x494F, 0x0BD0) },
+	{ PCI_DEVICE(0x494F, 0x07D0) }, { PCI_DEVICE(0x494F, 0x0FC0) },
+	{ 0 }
+};
+MODULE_DEVICE_TABLE(pci, idio_24_pci_dev_id);
+
+static struct pci_driver idio_24_driver = {
+	.name = "pcie-idio-24",
+	.id_table = idio_24_pci_dev_id,
+	.probe = idio_24_probe
+};
+
+module_pci_driver(idio_24_driver);
+
+MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
+MODULE_DESCRIPTION("ACCES PCIe-IDIO-24 GPIO driver");
+MODULE_LICENSE("GPL v2");