mfd: Add HTCPLD driver

This change introduces a driver for the HTC PLD chip found
on some smartphones, such as the HTC Wizard and HTC Herald.
It works through the I2C bus and acts as a GPIO extender.
Specifically:

 * it can have several sub-devices, each with its own I2C
   address
 * Each sub-device provides 8 output and 8 input pins
 * The chip attaches to one GPIO to signal when any of the
   input GPIOs change -- at which point all chips must be
   scanned for changes

This driver implements the GPIOs throught the kernel's
GPIO and IRQ framework.  This allows any GPIO-servicing
drivers to operate on htcpld pins, such as the gpio-keys
and gpio-leds drivers.
Signed-off-by: Cory Maccarrone <darkstar6262@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/mfd/Kconfig

@@ -78,6 +78,15 @@ config HTC_PASIC3
 	  HTC Magician devices, respectively. Actual functionality is
 	  handled by the leds-pasic3 and ds1wm drivers.
 
+config HTC_I2CPLD
+	bool "HTC I2C PLD chip support"
+	depends on I2C=y
+	help
+	  If you say yes here you get support for the supposed CPLD
+	  found on omap850 HTC devices like the HTC Wizard and HTC Herald.
+	  This device provides input and output GPIOs through an I2C
+	  interface to one or more sub-chips.
+
 config UCB1400_CORE
 	tristate "Philips UCB1400 Core driver"
 	depends on AC97_BUS

drivers/mfd/Makefile

@@ -10,6 +10,7 @@ obj-$(CONFIG_MFD_SH_MOBILE_SDHI)		+= sh_mobile_sdhi.o
 
 obj-$(CONFIG_HTC_EGPIO)		+= htc-egpio.o
 obj-$(CONFIG_HTC_PASIC3)	+= htc-pasic3.o
+obj-$(CONFIG_HTC_I2CPLD)	+= htc-i2cpld.o
 
 obj-$(CONFIG_MFD_DM355EVM_MSP)	+= dm355evm_msp.o
 

drivers/mfd/htc-i2cpld.c

+/*
+ *  htc-i2cpld.c
+ *  Chip driver for an unknown CPLD chip found on omap850 HTC devices like
+ *  the HTC Wizard and HTC Herald.
+ *  The cpld is located on the i2c bus and acts as an input/output GPIO
+ *  extender.
+ *
+ *  Copyright (C) 2009 Cory Maccarrone <darkstar6262@gmail.com>
+ *
+ *  Based on work done in the linwizard project
+ *  Copyright (C) 2008-2009 Angelo Arrifano <miknix@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/i2c.h>
+#include <linux/irq.h>
+#include <linux/spinlock.h>
+#include <linux/htcpld.h>
+#include <linux/gpio.h>
+
+struct htcpld_chip {
+	spinlock_t              lock;
+
+	/* chip info */
+	u8                      reset;
+	u8                      addr;
+	struct device           *dev;
+	struct i2c_client	*client;
+
+	/* Output details */
+	u8                      cache_out;
+	struct gpio_chip        chip_out;
+
+	/* Input details */
+	u8                      cache_in;
+	struct gpio_chip        chip_in;
+
+	u16                     irqs_enabled;
+	uint                    irq_start;
+	int                     nirqs;
+
+	/*
+	 * Work structure to allow for setting values outside of any
+	 * possible interrupt context
+	 */
+	struct work_struct set_val_work;
+};
+
+struct htcpld_data {
+	/* irq info */
+	u16                irqs_enabled;
+	uint               irq_start;
+	int                nirqs;
+	uint               chained_irq;
+	unsigned int       int_reset_gpio_hi;
+	unsigned int       int_reset_gpio_lo;
+
+	/* htcpld info */
+	struct htcpld_chip *chip;
+	unsigned int       nchips;
+};
+
+/* There does not appear to be a way to proactively mask interrupts
+ * on the htcpld chip itself.  So, we simply ignore interrupts that
+ * aren't desired. */
+static void htcpld_mask(unsigned int irq)
+{
+	struct htcpld_chip *chip = get_irq_chip_data(irq);
+	chip->irqs_enabled &= ~(1 << (irq - chip->irq_start));
+	pr_debug("HTCPLD mask %d %04x\n", irq, chip->irqs_enabled);
+}
+static void htcpld_unmask(unsigned int irq)
+{
+	struct htcpld_chip *chip = get_irq_chip_data(irq);
+	chip->irqs_enabled |= 1 << (irq - chip->irq_start);
+	pr_debug("HTCPLD unmask %d %04x\n", irq, chip->irqs_enabled);
+}
+
+static int htcpld_set_type(unsigned int irq, unsigned int flags)
+{
+	struct irq_desc *d = irq_to_desc(irq);
+
+	if (!d) {
+		pr_err("HTCPLD invalid IRQ: %d\n", irq);
+		return -EINVAL;
+	}
+
+	if (flags & ~IRQ_TYPE_SENSE_MASK)
+		return -EINVAL;
+
+	/* We only allow edge triggering */
+	if (flags & (IRQ_TYPE_LEVEL_LOW|IRQ_TYPE_LEVEL_HIGH))
+		return -EINVAL;
+
+	d->status &= ~IRQ_TYPE_SENSE_MASK;
+	d->status |= flags;
+
+	return 0;
+}
+
+static struct irq_chip htcpld_muxed_chip = {
+	.name     = "htcpld",
+	.mask     = htcpld_mask,
+	.unmask   = htcpld_unmask,
+	.set_type = htcpld_set_type,
+};
+
+/* To properly dispatch IRQ events, we need to read from the
+ * chip.  This is an I2C action that could possibly sleep
+ * (which is bad in interrupt context) -- so we use a threaded
+ * interrupt handler to get around that.
+ */
+static irqreturn_t htcpld_handler(int irq, void *dev)
+{
+	struct htcpld_data *htcpld = dev;
+	unsigned int i;
+	unsigned long flags;
+	int irqpin;
+	struct irq_desc *desc;
+
+	if (!htcpld) {
+		pr_debug("htcpld is null in ISR\n");
+		return IRQ_HANDLED;
+	}
+
+	/*
+	 * For each chip, do a read of the chip and trigger any interrupts
+	 * desired.  The interrupts will be triggered from LSB to MSB (i.e.
+	 * bit 0 first, then bit 1, etc.)
+	 *
+	 * For chips that have no interrupt range specified, just skip 'em.
+	 */
+	for (i = 0; i < htcpld->nchips; i++) {
+		struct htcpld_chip *chip = &htcpld->chip[i];
+		struct i2c_client *client;
+		int val;
+		unsigned long uval, old_val;
+
+		if (!chip) {
+			pr_debug("chip %d is null in ISR\n", i);
+			continue;
+		}
+
+		if (chip->nirqs == 0)
+			continue;
+
+		client = chip->client;
+		if (!client) {
+			pr_debug("client %d is null in ISR\n", i);
+			continue;
+		}
+
+		/* Scan the chip */
+		val = i2c_smbus_read_byte_data(client, chip->cache_out);
+		if (val < 0) {
+			/* Throw a warning and skip this chip */
+			dev_warn(chip->dev, "Unable to read from chip: %d\n",
+				 val);
+			continue;
+		}
+
+		uval = (unsigned long)val;
+
+		spin_lock_irqsave(&chip->lock, flags);
+
+		/* Save away the old value so we can compare it */
+		old_val = chip->cache_in;
+
+		/* Write the new value */
+		chip->cache_in = uval;
+
+		spin_unlock_irqrestore(&chip->lock, flags);
+
+		/*
+		 * For each bit in the data (starting at bit 0), trigger
+		 * associated interrupts.
+		 */
+		for (irqpin = 0; irqpin < chip->nirqs; irqpin++) {
+			unsigned oldb, newb;
+			int flags;
+
+			irq = chip->irq_start + irqpin;
+			desc = irq_to_desc(irq);
+			flags = desc->status;
+
+			/* Run the IRQ handler, but only if the bit value
+			 * changed, and the proper flags are set */
+			oldb = (old_val >> irqpin) & 1;
+			newb = (uval >> irqpin) & 1;
+
+			if ((!oldb && newb && (flags & IRQ_TYPE_EDGE_RISING)) ||
+			    (oldb && !newb &&
+			     (flags & IRQ_TYPE_EDGE_FALLING))) {
+				pr_debug("fire IRQ %d\n", irqpin);
+				desc->handle_irq(irq, desc);
+			}
+		}
+	}
+
+	/*
+	 * In order to continue receiving interrupts, the int_reset_gpio must
+	 * be asserted.
+	 */
+	if (htcpld->int_reset_gpio_hi)
+		gpio_set_value(htcpld->int_reset_gpio_hi, 1);
+	if (htcpld->int_reset_gpio_lo)
+		gpio_set_value(htcpld->int_reset_gpio_lo, 0);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * The GPIO set routines can be called from interrupt context, especially if,
+ * for example they're attached to the led-gpio framework and a trigger is
+ * enabled.  As such, we declared work above in the htcpld_chip structure,
+ * and that work is scheduled in the set routine.  The kernel can then run
+ * the I2C functions, which will sleep, in process context.
+ */
+void htcpld_chip_set(struct gpio_chip *chip, unsigned offset, int val)
+{
+	struct i2c_client *client;
+	struct htcpld_chip *chip_data;
+	unsigned long flags;
+
+	chip_data = container_of(chip, struct htcpld_chip, chip_out);
+	if (!chip_data)
+		return;
+
+	client = chip_data->client;
+	if (client == NULL)
+		return;
+
+	spin_lock_irqsave(&chip_data->lock, flags);
+	if (val)
+		chip_data->cache_out |= (1 << offset);
+	else
+		chip_data->cache_out &= ~(1 << offset);
+	spin_unlock_irqrestore(&chip_data->lock, flags);
+
+	schedule_work(&(chip_data->set_val_work));
+}
+
+void htcpld_chip_set_ni(struct work_struct *work)
+{
+	struct htcpld_chip *chip_data;
+	struct i2c_client *client;
+
+	chip_data = container_of(work, struct htcpld_chip, set_val_work);
+	client = chip_data->client;
+	i2c_smbus_read_byte_data(client, chip_data->cache_out);
+}
+
+int htcpld_chip_get(struct gpio_chip *chip, unsigned offset)
+{
+	struct htcpld_chip *chip_data;
+	int val = 0;
+	int is_input = 0;
+
+	/* Try out first */
+	chip_data = container_of(chip, struct htcpld_chip, chip_out);
+	if (!chip_data) {
+		/* Try in */
+		is_input = 1;
+		chip_data = container_of(chip, struct htcpld_chip, chip_in);
+		if (!chip_data)
+			return -EINVAL;
+	}
+
+	/* Determine if this is an input or output GPIO */
+	if (!is_input)
+		/* Use the output cache */
+		val = (chip_data->cache_out >> offset) & 1;
+	else
+		/* Use the input cache */
+		val = (chip_data->cache_in >> offset) & 1;
+
+	if (val)
+		return 1;
+	else
+		return 0;
+}
+
+static int htcpld_direction_output(struct gpio_chip *chip,
+					unsigned offset, int value)
+{
+	htcpld_chip_set(chip, offset, value);
+	return 0;
+}
+
+static int htcpld_direction_input(struct gpio_chip *chip,
+					unsigned offset)
+{
+	/*
+	 * No-op: this function can only be called on the input chip.
+	 * We do however make sure the offset is within range.
+	 */
+	return (offset < chip->ngpio) ? 0 : -EINVAL;
+}
+
+int htcpld_chip_to_irq(struct gpio_chip *chip, unsigned offset)
+{
+	struct htcpld_chip *chip_data;
+
+	chip_data = container_of(chip, struct htcpld_chip, chip_in);
+
+	if (offset < chip_data->nirqs)
+		return chip_data->irq_start + offset;
+	else
+		return -EINVAL;
+}
+
+void htcpld_chip_reset(struct i2c_client *client)
+{
+	struct htcpld_chip *chip_data = i2c_get_clientdata(client);
+	if (!chip_data)
+		return;
+
+	i2c_smbus_read_byte_data(
+		client, (chip_data->cache_out = chip_data->reset));
+}
+
+static int __devinit htcpld_setup_chip_irq(
+		struct platform_device *pdev,
+		int chip_index)
+{
+	struct htcpld_data *htcpld;
+	struct device *dev = &pdev->dev;
+	struct htcpld_core_platform_data *pdata;
+	struct htcpld_chip *chip;
+	struct htcpld_chip_platform_data *plat_chip_data;
+	unsigned int irq, irq_end;
+	int ret = 0;
+
+	/* Get the platform and driver data */
+	pdata = dev->platform_data;
+	htcpld = platform_get_drvdata(pdev);
+	chip = &htcpld->chip[chip_index];
+	plat_chip_data = &pdata->chip[chip_index];
+
+	/* Setup irq handlers */
+	irq_end = chip->irq_start + chip->nirqs;
+	for (irq = chip->irq_start; irq < irq_end; irq++) {
+		set_irq_chip(irq, &htcpld_muxed_chip);
+		set_irq_chip_data(irq, chip);
+		set_irq_handler(irq, handle_simple_irq);
+#ifdef CONFIG_ARM
+		set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
+#else
+		set_irq_probe(irq);
+#endif
+	}
+
+	return ret;
+}
+
+static int __devinit htcpld_register_chip_i2c(
+		struct platform_device *pdev,
+		int chip_index)
+{
+	struct htcpld_data *htcpld;
+	struct device *dev = &pdev->dev;
+	struct htcpld_core_platform_data *pdata;
+	struct htcpld_chip *chip;
+	struct htcpld_chip_platform_data *plat_chip_data;
+	struct i2c_adapter *adapter;
+	struct i2c_client *client;
+	struct i2c_board_info info;
+
+	/* Get the platform and driver data */
+	pdata = dev->platform_data;
+	htcpld = platform_get_drvdata(pdev);
+	chip = &htcpld->chip[chip_index];
+	plat_chip_data = &pdata->chip[chip_index];
+
+	adapter = i2c_get_adapter(pdata->i2c_adapter_id);
+	if (adapter == NULL) {
+		/* Eek, no such I2C adapter!  Bail out. */
+		dev_warn(dev, "Chip at i2c address 0x%x: Invalid i2c adapter %d\n",
+			 plat_chip_data->addr, pdata->i2c_adapter_id);
+		return -ENODEV;
+	}
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
+		dev_warn(dev, "i2c adapter %d non-functional\n",
+			 pdata->i2c_adapter_id);
+		return -EINVAL;
+	}
+
+	memset(&info, 0, sizeof(struct i2c_board_info));
+	info.addr = plat_chip_data->addr;
+	strlcpy(info.type, "htcpld-chip", I2C_NAME_SIZE);
+	info.platform_data = chip;
+
+	/* Add the I2C device.  This calls the probe() function. */
+	client = i2c_new_device(adapter, &info);
+	if (!client) {
+		/* I2C device registration failed, contineu with the next */
+		dev_warn(dev, "Unable to add I2C device for 0x%x\n",
+			 plat_chip_data->addr);
+		return -ENODEV;
+	}
+
+	i2c_set_clientdata(client, chip);
+	snprintf(client->name, I2C_NAME_SIZE, "Chip_0x%d", client->addr);
+	chip->client = client;
+
+	/* Reset the chip */
+	htcpld_chip_reset(client);
+	chip->cache_in = i2c_smbus_read_byte_data(client, chip->cache_out);
+
+	return 0;
+}
+
+static void __devinit htcpld_unregister_chip_i2c(
+		struct platform_device *pdev,
+		int chip_index)
+{
+	struct htcpld_data *htcpld;
+	struct htcpld_chip *chip;
+
+	/* Get the platform and driver data */
+	htcpld = platform_get_drvdata(pdev);
+	chip = &htcpld->chip[chip_index];
+
+	if (chip->client)
+		i2c_unregister_device(chip->client);
+}
+
+static int __devinit htcpld_register_chip_gpio(
+		struct platform_device *pdev,
+		int chip_index)
+{
+	struct htcpld_data *htcpld;
+	struct device *dev = &pdev->dev;
+	struct htcpld_core_platform_data *pdata;
+	struct htcpld_chip *chip;
+	struct htcpld_chip_platform_data *plat_chip_data;
+	struct gpio_chip *gpio_chip;
+	int ret = 0;
+
+	/* Get the platform and driver data */
+	pdata = dev->platform_data;
+	htcpld = platform_get_drvdata(pdev);
+	chip = &htcpld->chip[chip_index];
+	plat_chip_data = &pdata->chip[chip_index];
+
+	/* Setup the GPIO chips */
+	gpio_chip = &(chip->chip_out);
+	gpio_chip->label           = "htcpld-out";
+	gpio_chip->dev             = dev;
+	gpio_chip->owner           = THIS_MODULE;
+	gpio_chip->get             = htcpld_chip_get;
+	gpio_chip->set             = htcpld_chip_set;
+	gpio_chip->direction_input = NULL;
+	gpio_chip->direction_output = htcpld_direction_output;
+	gpio_chip->base            = plat_chip_data->gpio_out_base;
+	gpio_chip->ngpio           = plat_chip_data->num_gpios;
+
+	gpio_chip = &(chip->chip_in);
+	gpio_chip->label           = "htcpld-in";
+	gpio_chip->dev             = dev;
+	gpio_chip->owner           = THIS_MODULE;
+	gpio_chip->get             = htcpld_chip_get;
+	gpio_chip->set             = NULL;
+	gpio_chip->direction_input = htcpld_direction_input;
+	gpio_chip->direction_output = NULL;
+	gpio_chip->to_irq          = htcpld_chip_to_irq;
+	gpio_chip->base            = plat_chip_data->gpio_in_base;
+	gpio_chip->ngpio           = plat_chip_data->num_gpios;
+
+	/* Add the GPIO chips */
+	ret = gpiochip_add(&(chip->chip_out));
+	if (ret) {
+		dev_warn(dev, "Unable to register output GPIOs for 0x%x: %d\n",
+			 plat_chip_data->addr, ret);
+		return ret;
+	}
+
+	ret = gpiochip_add(&(chip->chip_in));
+	if (ret) {
+		int error;
+
+		dev_warn(dev, "Unable to register input GPIOs for 0x%x: %d\n",
+			 plat_chip_data->addr, ret);
+
+		error = gpiochip_remove(&(chip->chip_out));
+		if (error)
+			dev_warn(dev, "Error while trying to unregister gpio chip: %d\n", error);
+
+		return ret;
+	}
+
+	return 0;
+}
+
+static int __devinit htcpld_setup_chips(struct platform_device *pdev)
+{
+	struct htcpld_data *htcpld;
+	struct device *dev = &pdev->dev;
+	struct htcpld_core_platform_data *pdata;
+	int i;
+
+	/* Get the platform and driver data */
+	pdata = dev->platform_data;
+	htcpld = platform_get_drvdata(pdev);
+
+	/* Setup each chip's output GPIOs */
+	htcpld->nchips = pdata->num_chip;
+	htcpld->chip = kzalloc(sizeof(struct htcpld_chip) * htcpld->nchips,
+			       GFP_KERNEL);
+	if (!htcpld->chip) {
+		dev_warn(dev, "Unable to allocate memory for chips\n");
+		return -ENOMEM;
+	}
+
+	/* Add the chips as best we can */
+	for (i = 0; i < htcpld->nchips; i++) {
+		int ret;
+
+		/* Setup the HTCPLD chips */
+		htcpld->chip[i].reset = pdata->chip[i].reset;
+		htcpld->chip[i].cache_out = pdata->chip[i].reset;
+		htcpld->chip[i].cache_in = 0;
+		htcpld->chip[i].dev = dev;
+		htcpld->chip[i].irq_start = pdata->chip[i].irq_base;
+		htcpld->chip[i].nirqs = pdata->chip[i].num_irqs;
+
+		INIT_WORK(&(htcpld->chip[i].set_val_work), &htcpld_chip_set_ni);
+		spin_lock_init(&(htcpld->chip[i].lock));
+
+		/* Setup the interrupts for the chip */
+		if (htcpld->chained_irq) {
+			ret = htcpld_setup_chip_irq(pdev, i);
+			if (ret)
+				continue;
+		}
+
+		/* Register the chip with I2C */
+		ret = htcpld_register_chip_i2c(pdev, i);
+		if (ret)
+			continue;
+
+
+		/* Register the chips with the GPIO subsystem */
+		ret = htcpld_register_chip_gpio(pdev, i);
+		if (ret) {
+			/* Unregister the chip from i2c and continue */
+			htcpld_unregister_chip_i2c(pdev, i);
+			continue;
+		}
+
+		dev_info(dev, "Registered chip at 0x%x\n", pdata->chip[i].addr);
+	}
+
+	return 0;
+}
+
+static int __devinit htcpld_core_probe(struct platform_device *pdev)
+{
+	struct htcpld_data *htcpld;
+	struct device *dev = &pdev->dev;
+	struct htcpld_core_platform_data *pdata;
+	struct resource *res;
+	int ret = 0;
+
+	if (!dev)
+		return -ENODEV;
+
+	pdata = dev->platform_data;
+	if (!pdata) {
+		dev_warn(dev, "Platform data not found for htcpld core!\n");
+		return -ENXIO;
+	}
+
+	htcpld = kzalloc(sizeof(struct htcpld_data), GFP_KERNEL);
+	if (!htcpld)
+		return -ENOMEM;
+
+	/* Find chained irq */
+	ret = -EINVAL;
+	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	if (res) {
+		int flags;
+		htcpld->chained_irq = res->start;
+
+		/* Setup the chained interrupt handler */
+		flags = IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING;
+		ret = request_threaded_irq(htcpld->chained_irq,
+					   NULL, htcpld_handler,
+					   flags, pdev->name, htcpld);
+		if (ret) {
+			dev_warn(dev, "Unable to setup chained irq handler: %d\n", ret);
+			goto fail;
+		} else
+			device_init_wakeup(dev, 0);
+	}
+
+	/* Set the driver data */
+	platform_set_drvdata(pdev, htcpld);
+
+	/* Setup the htcpld chips */
+	ret = htcpld_setup_chips(pdev);
+	if (ret)
+		goto fail;
+
+	/* Request the GPIO(s) for the int reset and set them up */
+	if (pdata->int_reset_gpio_hi) {
+		ret = gpio_request(pdata->int_reset_gpio_hi, "htcpld-core");
+		if (ret) {
+			/*
+			 * If it failed, that sucks, but we can probably
+			 * continue on without it.
+			 */
+			dev_warn(dev, "Unable to request int_reset_gpio_hi -- interrupts may not work\n");
+			htcpld->int_reset_gpio_hi = 0;
+		} else {
+			htcpld->int_reset_gpio_hi = pdata->int_reset_gpio_hi;
+			gpio_set_value(htcpld->int_reset_gpio_hi, 1);
+		}
+	}
+
+	if (pdata->int_reset_gpio_lo) {
+		ret = gpio_request(pdata->int_reset_gpio_lo, "htcpld-core");
+		if (ret) {
+			/*
+			 * If it failed, that sucks, but we can probably
+			 * continue on without it.
+			 */
+			dev_warn(dev, "Unable to request int_reset_gpio_lo -- interrupts may not work\n");
+			htcpld->int_reset_gpio_lo = 0;
+		} else {
+			htcpld->int_reset_gpio_lo = pdata->int_reset_gpio_lo;
+			gpio_set_value(htcpld->int_reset_gpio_lo, 0);
+		}
+	}
+
+	dev_info(dev, "Initialized successfully\n");
+	return 0;
+
+fail:
+	kfree(htcpld);
+	return ret;
+}
+
+/* The I2C Driver -- used internally */
+static const struct i2c_device_id htcpld_chip_id[] = {
+	{ "htcpld-chip", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, htcpld_chip_id);
+
+
+static struct i2c_driver htcpld_chip_driver = {
+	.driver = {
+		.name	= "htcpld-chip",
+	},
+	.id_table = htcpld_chip_id,
+};
+
+/* The Core Driver */
+static struct platform_driver htcpld_core_driver = {
+	.driver = {
+		.name = "i2c-htcpld",
+	},
+};
+
+static int __init htcpld_core_init(void)
+{
+	int ret;
+
+	/* Register the I2C Chip driver */
+	ret = i2c_add_driver(&htcpld_chip_driver);
+	if (ret)
+		return ret;
+
+	/* Probe for our chips */
+	return platform_driver_probe(&htcpld_core_driver, htcpld_core_probe);
+}
+
+static void __exit htcpld_core_exit(void)
+{
+	i2c_del_driver(&htcpld_chip_driver);
+	platform_driver_unregister(&htcpld_core_driver);
+}
+
+module_init(htcpld_core_init);
+module_exit(htcpld_core_exit);
+
+MODULE_AUTHOR("Cory Maccarrone <darkstar6262@gmail.com>");
+MODULE_DESCRIPTION("I2C HTC PLD Driver");
+MODULE_LICENSE("GPL");
+

include/linux/htcpld.h

+#ifndef __LINUX_HTCPLD_H
+#define __LINUX_HTCPLD_H
+
+struct htcpld_chip_platform_data {
+	unsigned int addr;
+	unsigned int reset;
+	unsigned int num_gpios;
+	unsigned int gpio_out_base;
+	unsigned int gpio_in_base;
+	unsigned int irq_base;
+	unsigned int num_irqs;
+};
+
+struct htcpld_core_platform_data {
+	unsigned int                      int_reset_gpio_hi;
+	unsigned int                      int_reset_gpio_lo;
+	unsigned int                      i2c_adapter_id;
+
+	struct htcpld_chip_platform_data  *chip;
+	unsigned int                      num_chip;
+};
+
+#endif /* __LINUX_HTCPLD_H */
+