htc-i2cpld.c

Go to the documentation of this file.

/*
 *  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 <[email protected]>
 *
 *  Based on work done in the linwizard project
 *  Copyright (C) 2008-2009 Angelo Arrifano <[email protected]>
 *
 * 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>
#include <linux/slab.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;

    unsigned int        flow_type;
    /*
     * 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(struct irq_data *data)
{
    struct htcpld_chip *chip = irq_data_get_irq_chip_data(data);
    chip->irqs_enabled &= ~(1 << (data->irq - chip->irq_start));
    pr_debug("HTCPLD mask %d %04x\n", data->irq, chip->irqs_enabled);
}
static void htcpld_unmask(struct irq_data *data)
{
    struct htcpld_chip *chip = irq_data_get_irq_chip_data(data);
    chip->irqs_enabled |= 1 << (data->irq - chip->irq_start);
    pr_debug("HTCPLD unmask %d %04x\n", data->irq, chip->irqs_enabled);
}

static int htcpld_set_type(struct irq_data *data, unsigned int flags)
{
    struct htcpld_chip *chip = irq_data_get_irq_chip_data(data);

    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;

    chip->flow_type = flags;
    return 0;
}

static struct irq_chip htcpld_muxed_chip = {
    .name         = "htcpld",
    .irq_mask     = htcpld_mask,
    .irq_unmask   = htcpld_unmask,
    .irq_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;

    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, type = chip->flow_type;

            irq = chip->irq_start + irqpin;

            /* 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 && (type & IRQ_TYPE_EDGE_RISING)) ||
                (oldb && !newb && (type & IRQ_TYPE_EDGE_FALLING))) {
                pr_debug("fire IRQ %d\n", irqpin);
                generic_handle_irq(irq);
            }
        }
    }

    /*
     * 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.
 */
static 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));
}

static 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);
}

static 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;
}

static 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;
}

static 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++) {
        irq_set_chip_and_handler(irq, &htcpld_muxed_chip,
                     handle_simple_irq);
        irq_set_chip_data(irq, chip);
#ifdef CONFIG_ARM
        set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
#else
        irq_set_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 <[email protected]>");
MODULE_DESCRIPTION("I2C HTC PLD Driver");
MODULE_LICENSE("GPL");