[ARM] 4947/1: htc-egpio, a driver for GPIO/IRQ expanders with fixed input/output pins

implemented in CPLD chips on several HTC devices.

The original driver was written by Kevin O'Connor, I have adapted it to
use gpiolib and made the bus/register widths configurable.

Signed-off-by: Philipp Zabel <[e-mail]>
Signed-off-by: Russell King <[e-mail]>

drivers/mfd/Kconfig

···
 	  This driver supports the ASIC3 multifunction chip found on many
 	  PDAs (mainly iPAQ and HTC based ones)
 
+config HTC_EGPIO
+	bool "HTC EGPIO support"
+	depends on GENERIC_HARDIRQS && HAVE_GPIO_LIB
+	help
+	    This driver supports the CPLD egpio chip present on
+	    several HTC phones.  It provides basic support for input
+	    pins, output pins, and irqs.
+
 endmenu
 
 menu "Multimedia Capabilities Port drivers"

drivers/mfd/Makefile

···
 obj-$(CONFIG_MFD_SM501)		+= sm501.o
 obj-$(CONFIG_MFD_ASIC3)		+= asic3.o
 
+obj-$(CONFIG_HTC_EGPIO)		+= htc-egpio.o
+
 obj-$(CONFIG_MCP)		+= mcp-core.o
 obj-$(CONFIG_MCP_SA11X0)	+= mcp-sa11x0.o
 obj-$(CONFIG_MCP_UCB1200)	+= ucb1x00-core.o

drivers/mfd/htc-egpio.c

···
+/*
+ * Support for the GPIO/IRQ expander chips present on several HTC phones.
+ * These are implemented in CPLD chips present on the board.
+ *
+ * Copyright (c) 2007 Kevin O'Connor <[e-mail]>
+ * Copyright (c) 2007 Philipp Zabel <[e-mail]>
+ *
+ * This file may be distributed under the terms of the GNU GPL license.
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/io.h>
+#include <linux/spinlock.h>
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <linux/mfd/htc-egpio.h>
+
+struct egpio_chip {
+	int              reg_start;
+	int              cached_values;
+	unsigned long    is_out;
+	struct device    *dev;
+	struct gpio_chip chip;
+};
+
+struct egpio_info {
+	spinlock_t        lock;
+
+	/* iomem info */
+	void __iomem      *base_addr;
+	int               bus_shift;	/* byte shift */
+	int               reg_shift;	/* bit shift */
+	int               reg_mask;
+
+	/* irq info */
+	int               ack_register;
+	int               ack_write;
+	u16               irqs_enabled;
+	uint              irq_start;
+	int               nirqs;
+	uint              chained_irq;
+
+	/* egpio info */
+	struct egpio_chip *chip;
+	int               nchips;
+};
+
+static inline void egpio_writew(u16 value, struct egpio_info *ei, int reg)
+{
+	writew(value, ei->base_addr + (reg << ei->bus_shift));
+}
+
+static inline u16 egpio_readw(struct egpio_info *ei, int reg)
+{
+	return readw(ei->base_addr + (reg << ei->bus_shift));
+}
+
+/*
+ * IRQs
+ */
+
+static inline void ack_irqs(struct egpio_info *ei)
+{
+	egpio_writew(ei->ack_write, ei, ei->ack_register);
+	pr_debug("EGPIO ack - write %x to base+%x\n",
+			ei->ack_write, ei->ack_register << ei->bus_shift);
+}
+
+static void egpio_ack(unsigned int irq)
+{
+}
+
+/* There does not appear to be a way to proactively mask interrupts
+ * on the egpio chip itself.  So, we simply ignore interrupts that
+ * aren't desired. */
+static void egpio_mask(unsigned int irq)
+{
+	struct egpio_info *ei = get_irq_chip_data(irq);
+	ei->irqs_enabled &= ~(1 << (irq - ei->irq_start));
+	pr_debug("EGPIO mask %d %04x\n", irq, ei->irqs_enabled);
+}
+static void egpio_unmask(unsigned int irq)
+{
+	struct egpio_info *ei = get_irq_chip_data(irq);
+	ei->irqs_enabled |= 1 << (irq - ei->irq_start);
+	pr_debug("EGPIO unmask %d %04x\n", irq, ei->irqs_enabled);
+}
+
+static struct irq_chip egpio_muxed_chip = {
+	.name   = "htc-egpio",
+	.ack	= egpio_ack,
+	.mask   = egpio_mask,
+	.unmask = egpio_unmask,
+};
+
+static void egpio_handler(unsigned int irq, struct irq_desc *desc)
+{
+	struct egpio_info *ei = get_irq_data(irq);
+	int irqpin;
+
+	/* Read current pins. */
+	unsigned long readval = egpio_readw(ei, ei->ack_register);
+	pr_debug("IRQ reg: %x\n", (unsigned int)readval);
+	/* Ack/unmask interrupts. */
+	ack_irqs(ei);
+	/* Process all set pins. */
+	readval &= ei->irqs_enabled;
+	for_each_bit(irqpin, &readval, ei->nirqs) {
+		/* Run irq handler */
+		pr_debug("got IRQ %d\n", irqpin);
+		irq = ei->irq_start + irqpin;
+		desc = &irq_desc[irq];
+		desc->handle_irq(irq, desc);
+	}
+}
+
+int htc_egpio_get_wakeup_irq(struct device *dev)
+{
+	struct egpio_info *ei = dev_get_drvdata(dev);
+
+	/* Read current pins. */
+	u16 readval = egpio_readw(ei, ei->ack_register);
+	/* Ack/unmask interrupts. */
+	ack_irqs(ei);
+	/* Return first set pin. */
+	readval &= ei->irqs_enabled;
+	return ei->irq_start + ffs(readval) - 1;
+}
+EXPORT_SYMBOL(htc_egpio_get_wakeup_irq);
+
+static inline int egpio_pos(struct egpio_info *ei, int bit)
+{
+	return bit >> ei->reg_shift;
+}
+
+static inline int egpio_bit(struct egpio_info *ei, int bit)
+{
+	return 1 << (bit & ((1 << ei->reg_shift)-1));
+}
+
+/*
+ * Input pins
+ */
+
+static int egpio_get(struct gpio_chip *chip, unsigned offset)
+{
+	struct egpio_chip *egpio;
+	struct egpio_info *ei;
+	unsigned           bit;
+	int                reg;
+	int                value;
+
+	pr_debug("egpio_get_value(%d)\n", chip->base + offset);
+
+	egpio = container_of(chip, struct egpio_chip, chip);
+	ei    = dev_get_drvdata(egpio->dev);
+	bit   = egpio_bit(ei, offset);
+	reg   = egpio->reg_start + egpio_pos(ei, offset);
+
+	value = egpio_readw(ei, reg);
+	pr_debug("readw(%p + %x) = %x\n",
+			ei->base_addr, reg << ei->bus_shift, value);
+	return value & bit;
+}
+
+static int egpio_direction_input(struct gpio_chip *chip, unsigned offset)
+{
+	struct egpio_chip *egpio;
+
+	egpio = container_of(chip, struct egpio_chip, chip);
+	return test_bit(offset, &egpio->is_out) ? -EINVAL : 0;
+}
+
+
+/*
+ * Output pins
+ */
+
+static void egpio_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+	unsigned long     flag;
+	struct egpio_chip *egpio;
+	struct egpio_info *ei;
+	unsigned          bit;
+	int               pos;
+	int               reg;
+	int               shift;
+
+	pr_debug("egpio_set(%s, %d(%d), %d)\n",
+			chip->label, offset, offset+chip->base, value);
+
+	egpio = container_of(chip, struct egpio_chip, chip);
+	ei    = dev_get_drvdata(egpio->dev);
+	bit   = egpio_bit(ei, offset);
+	pos   = egpio_pos(ei, offset);
+	reg   = egpio->reg_start + pos;
+	shift = pos << ei->reg_shift;
+
+	pr_debug("egpio %s: reg %d = 0x%04x\n", value ? "set" : "clear",
+			reg, (egpio->cached_values >> shift) & ei->reg_mask);
+
+	spin_lock_irqsave(&ei->lock, flag);
+	if (value)
+		egpio->cached_values |= (1 << offset);
+	else
+		egpio->cached_values &= ~(1 << offset);
+	egpio_writew((egpio->cached_values >> shift) & ei->reg_mask, ei, reg);
+	spin_unlock_irqrestore(&ei->lock, flag);
+}
+
+static int egpio_direction_output(struct gpio_chip *chip,
+					unsigned offset, int value)
+{
+	struct egpio_chip *egpio;
+
+	egpio = container_of(chip, struct egpio_chip, chip);
+	if (test_bit(offset, &egpio->is_out)) {
+		egpio_set(chip, offset, value);
+		return 0;
+	} else {
+		return -EINVAL;
+	}
+}
+
+static void egpio_write_cache(struct egpio_info *ei)
+{
+	int               i;
+	struct egpio_chip *egpio;
+	int               shift;
+
+	for (i = 0; i < ei->nchips; i++) {
+		egpio = &(ei->chip[i]);
+		if (!egpio->is_out)
+			continue;
+
+		for (shift = 0; shift < egpio->chip.ngpio;
+				shift += (1<<ei->reg_shift)) {
+
+			int reg = egpio->reg_start + egpio_pos(ei, shift);
+
+			if (!((egpio->is_out >> shift) & ei->reg_mask))
+				continue;
+
+			pr_debug("EGPIO: setting %x to %x, was %x\n", reg,
+				(egpio->cached_values >> shift) & ei->reg_mask,
+				egpio_readw(ei, reg));
+
+			egpio_writew((egpio->cached_values >> shift)
+					& ei->reg_mask, ei, reg);
+		}
+	}
+}
+
+
+/*
+ * Setup
+ */
+
+static int __init egpio_probe(struct platform_device *pdev)
+{
+	struct htc_egpio_platform_data *pdata = pdev->dev.platform_data;
+	struct resource   *res;
+	struct egpio_info *ei;
+	struct gpio_chip  *chip;
+	unsigned int      irq, irq_end;
+	int               i;
+	int               ret;
+
+	/* Initialize ei data structure. */
+	ei = kzalloc(sizeof(*ei), GFP_KERNEL);
+	if (!ei)
+		return -ENOMEM;
+
+	spin_lock_init(&ei->lock);
+
+	/* Find chained irq */
+	ret = -EINVAL;
+	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	if (res)
+		ei->chained_irq = res->start;
+
+	/* Map egpio chip into virtual address space. */
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		goto fail;
+	ei->base_addr = ioremap_nocache(res->start, res->end - res->start);
+	if (!ei->base_addr)
+		goto fail;
+	pr_debug("EGPIO phys=%08x virt=%p\n", res->start, ei->base_addr);
+
+	if ((pdata->bus_width != 16) && (pdata->bus_width != 32))
+		goto fail;
+	ei->bus_shift = fls(pdata->bus_width - 1) - 3;
+	pr_debug("bus_shift = %d\n", ei->bus_shift);
+
+	if ((pdata->reg_width != 8) && (pdata->reg_width != 16))
+		goto fail;
+	ei->reg_shift = fls(pdata->reg_width - 1);
+	pr_debug("reg_shift = %d\n", ei->reg_shift);
+
+	ei->reg_mask = (1 << pdata->reg_width) - 1;
+
+	platform_set_drvdata(pdev, ei);
+
+	ei->nchips = pdata->num_chips;
+	ei->chip = kzalloc(sizeof(struct egpio_chip) * ei->nchips, GFP_KERNEL);
+	if (!ei) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+	for (i = 0; i < ei->nchips; i++) {
+		ei->chip[i].reg_start = pdata->chip[i].reg_start;
+		ei->chip[i].cached_values = pdata->chip[i].initial_values;
+		ei->chip[i].is_out = pdata->chip[i].direction;
+		ei->chip[i].dev = &(pdev->dev);
+		chip = &(ei->chip[i].chip);
+		chip->label           = "htc-egpio";
+		chip->get             = egpio_get;
+		chip->set             = egpio_set;
+		chip->direction_input = egpio_direction_input;
+		chip->direction_output = egpio_direction_output;
+		chip->base            = pdata->chip[i].gpio_base;
+		chip->ngpio           = pdata->chip[i].num_gpios;
+
+		gpiochip_add(chip);
+	}
+
+	/* Set initial pin values */
+	egpio_write_cache(ei);
+
+	ei->irq_start = pdata->irq_base;
+	ei->nirqs = pdata->num_irqs;
+	ei->ack_register = pdata->ack_register;
+
+	if (ei->chained_irq) {
+		/* Setup irq handlers */
+		ei->ack_write = 0xFFFF;
+		if (pdata->invert_acks)
+			ei->ack_write = 0;
+		irq_end = ei->irq_start + ei->nirqs;
+		for (irq = ei->irq_start; irq < irq_end; irq++) {
+			set_irq_chip(irq, &egpio_muxed_chip);
+			set_irq_chip_data(irq, ei);
+			set_irq_handler(irq, handle_simple_irq);
+			set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
+		}
+		set_irq_type(ei->chained_irq, IRQ_TYPE_EDGE_RISING);
+		set_irq_data(ei->chained_irq, ei);
+		set_irq_chained_handler(ei->chained_irq, egpio_handler);
+		ack_irqs(ei);
+
+		device_init_wakeup(&pdev->dev, 1);
+	}
+
+	return 0;
+
+fail:
+	printk(KERN_ERR "EGPIO failed to setup\n");
+	kfree(ei);
+	return ret;
+}
+
+static int __exit egpio_remove(struct platform_device *pdev)
+{
+	struct egpio_info *ei = platform_get_drvdata(pdev);
+	unsigned int      irq, irq_end;
+
+	if (ei->chained_irq) {
+		irq_end = ei->irq_start + ei->nirqs;
+		for (irq = ei->irq_start; irq < irq_end; irq++) {
+			set_irq_chip(irq, NULL);
+			set_irq_handler(irq, NULL);
+			set_irq_flags(irq, 0);
+		}
+		set_irq_chained_handler(ei->chained_irq, NULL);
+		device_init_wakeup(&pdev->dev, 0);
+	}
+	iounmap(ei->base_addr);
+	kfree(ei->chip);
+	kfree(ei);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int egpio_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	struct egpio_info *ei = platform_get_drvdata(pdev);
+
+	if (ei->chained_irq && device_may_wakeup(&pdev->dev))
+		enable_irq_wake(ei->chained_irq);
+	return 0;
+}
+
+static int egpio_resume(struct platform_device *pdev)
+{
+	struct egpio_info *ei = platform_get_drvdata(pdev);
+
+	if (ei->chained_irq && device_may_wakeup(&pdev->dev))
+		disable_irq_wake(ei->chained_irq);
+
+	/* Update registers from the cache, in case
+	   the CPLD was powered off during suspend */
+	egpio_write_cache(ei);
+	return 0;
+}
+#else
+#define egpio_suspend NULL
+#define egpio_resume NULL
+#endif
+
+
+static struct platform_driver egpio_driver = {
+	.driver = {
+		.name = "htc-egpio",
+	},
+	.remove       = __exit_p(egpio_remove),
+	.suspend      = egpio_suspend,
+	.resume       = egpio_resume,
+};
+
+static int __init egpio_init(void)
+{
+	return platform_driver_probe(&egpio_driver, egpio_probe);
+}
+
+static void __exit egpio_exit(void)
+{
+	platform_driver_unregister(&egpio_driver);
+}
+
+/* start early for dependencies */
+subsys_initcall(egpio_init);
+module_exit(egpio_exit)
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Kevin O'Connor <[e-mail]>");

include/linux/mfd/htc-egpio.h

···
+/*
+ * HTC simple EGPIO irq and gpio extender
+ */
+
+#ifndef __HTC_EGPIO_H__
+#define __HTC_EGPIO_H__
+
+#include <linux/gpio.h>
+
+/* Descriptive values for all-in or all-out htc_egpio_chip descriptors. */
+#define HTC_EGPIO_OUTPUT (~0)
+#define HTC_EGPIO_INPUT  0
+
+/**
+ * struct htc_egpio_chip - descriptor to create gpio_chip for register range
+ * @reg_start: index of first register
+ * @gpio_base: gpio number of first pin in this register range
+ * @num_gpios: number of gpios in this register range, max BITS_PER_LONG
+ *    (number of registers = DIV_ROUND_UP(num_gpios, reg_width))
+ * @direction: bitfield, '0' = input, '1' = output,
+ */
+struct htc_egpio_chip {
+	int           reg_start;
+	int           gpio_base;
+	int           num_gpios;
+	unsigned long direction;
+	unsigned long initial_values;
+};
+
+/**
+ * struct htc_egpio_platform_data - description provided by the arch
+ * @irq_base: beginning of available IRQs (eg, IRQ_BOARD_START)
+ * @num_irqs: number of irqs
+ * @reg_width: number of bits per register, either 8 or 16 bit
+ * @bus_width: alignment of the registers, either 16 or 32 bit
+ * @invert_acks: set if chip requires writing '0' to ack an irq, instead of '1'
+ * @ack_register: location of the irq/ack register
+ * @chip: pointer to array of htc_egpio_chip descriptors
+ * @num_chips: number of egpio chip descriptors
+ */
+struct htc_egpio_platform_data {
+	int                   bus_width;
+	int                   reg_width;
+
+	int                   irq_base;
+	int                   num_irqs;
+	int                   invert_acks;
+	int                   ack_register;
+
+	struct htc_egpio_chip *chip;
+	int                   num_chips;
+};
+
+/* Determine the wakeup irq, to be called during early resume */
+extern int htc_egpio_get_wakeup_irq(struct device *dev);
+
+#endif