jbd: Fix a race between checkpointing code and journal_get_write_access()

[linux/fpc-iii.git] / drivers / mfd / ucb1x00-core.c

/*
 *  linux/drivers/mfd/ucb1x00-core.c
 *
 *  Copyright (C) 2001 Russell King, All Rights Reserved.
 *
 * 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.
 *
 *  The UCB1x00 core driver provides basic services for handling IO,
 *  the ADC, interrupts, and accessing registers.  It is designed
 *  such that everything goes through this layer, thereby providing
 *  a consistent locking methodology, as well as allowing the drivers
 *  to be used on other non-MCP-enabled hardware platforms.
 *
 *  Note that all locks are private to this file.  Nothing else may
 *  touch them.
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/mutex.h>

#include <mach/dma.h>
#include <mach/hardware.h>

#include "ucb1x00.h"

static DEFINE_MUTEX(ucb1x00_mutex);
static LIST_HEAD(ucb1x00_drivers);
static LIST_HEAD(ucb1x00_devices);

/**
 *      ucb1x00_io_set_dir - set IO direction
 *      @ucb: UCB1x00 structure describing chip
 *      @in:  bitfield of IO pins to be set as inputs
 *      @out: bitfield of IO pins to be set as outputs
 *
 *      Set the IO direction of the ten general purpose IO pins on
 *      the UCB1x00 chip.  The @in bitfield has priority over the
 *      @out bitfield, in that if you specify a pin as both input
 *      and output, it will end up as an input.
 *
 *      ucb1x00_enable must have been called to enable the comms
 *      before using this function.
 *
 *      This function takes a spinlock, disabling interrupts.
 */
void ucb1x00_io_set_dir(struct ucb1x00 *ucb, unsigned int in, unsigned int out)
{
        unsigned long flags;

        spin_lock_irqsave(&ucb->io_lock, flags);
        ucb->io_dir |= out;
        ucb->io_dir &= ~in;

        ucb1x00_reg_write(ucb, UCB_IO_DIR, ucb->io_dir);
        spin_unlock_irqrestore(&ucb->io_lock, flags);
}

/**
 *      ucb1x00_io_write - set or clear IO outputs
 *      @ucb:   UCB1x00 structure describing chip
 *      @set:   bitfield of IO pins to set to logic '1'
 *      @clear: bitfield of IO pins to set to logic '0'
 *
 *      Set the IO output state of the specified IO pins.  The value
 *      is retained if the pins are subsequently configured as inputs.
 *      The @clear bitfield has priority over the @set bitfield -
 *      outputs will be cleared.
 *
 *      ucb1x00_enable must have been called to enable the comms
 *      before using this function.
 *
 *      This function takes a spinlock, disabling interrupts.
 */
void ucb1x00_io_write(struct ucb1x00 *ucb, unsigned int set, unsigned int clear)
{
        unsigned long flags;

        spin_lock_irqsave(&ucb->io_lock, flags);
        ucb->io_out |= set;
        ucb->io_out &= ~clear;

        ucb1x00_reg_write(ucb, UCB_IO_DATA, ucb->io_out);
        spin_unlock_irqrestore(&ucb->io_lock, flags);
}

/**
 *      ucb1x00_io_read - read the current state of the IO pins
 *      @ucb: UCB1x00 structure describing chip
 *
 *      Return a bitfield describing the logic state of the ten
 *      general purpose IO pins.
 *
 *      ucb1x00_enable must have been called to enable the comms
 *      before using this function.
 *
 *      This function does not take any semaphores or spinlocks.
 */
unsigned int ucb1x00_io_read(struct ucb1x00 *ucb)
{
        return ucb1x00_reg_read(ucb, UCB_IO_DATA);
}

/*
 * UCB1300 data sheet says we must:
 *  1. enable ADC       => 5us (including reference startup time)
 *  2. select input     => 51*tsibclk  => 4.3us
 *  3. start conversion => 102*tsibclk => 8.5us
 * (tsibclk = 1/11981000)
 * Period between SIB 128-bit frames = 10.7us
 */

/**
 *      ucb1x00_adc_enable - enable the ADC converter
 *      @ucb: UCB1x00 structure describing chip
 *
 *      Enable the ucb1x00 and ADC converter on the UCB1x00 for use.
 *      Any code wishing to use the ADC converter must call this
 *      function prior to using it.
 *
 *      This function takes the ADC semaphore to prevent two or more
 *      concurrent uses, and therefore may sleep.  As a result, it
 *      can only be called from process context, not interrupt
 *      context.
 *
 *      You should release the ADC as soon as possible using
 *      ucb1x00_adc_disable.
 */
void ucb1x00_adc_enable(struct ucb1x00 *ucb)
{
        down(&ucb->adc_sem);

        ucb->adc_cr |= UCB_ADC_ENA;

        ucb1x00_enable(ucb);
        ucb1x00_reg_write(ucb, UCB_ADC_CR, ucb->adc_cr);
}

/**
 *      ucb1x00_adc_read - read the specified ADC channel
 *      @ucb: UCB1x00 structure describing chip
 *      @adc_channel: ADC channel mask
 *      @sync: wait for syncronisation pulse.
 *
 *      Start an ADC conversion and wait for the result.  Note that
 *      synchronised ADC conversions (via the ADCSYNC pin) must wait
 *      until the trigger is asserted and the conversion is finished.
 *
 *      This function currently spins waiting for the conversion to
 *      complete (2 frames max without sync).
 *
 *      If called for a synchronised ADC conversion, it may sleep
 *      with the ADC semaphore held.
 */
unsigned int ucb1x00_adc_read(struct ucb1x00 *ucb, int adc_channel, int sync)
{
        unsigned int val;

        if (sync)
                adc_channel |= UCB_ADC_SYNC_ENA;

        ucb1x00_reg_write(ucb, UCB_ADC_CR, ucb->adc_cr | adc_channel);
        ucb1x00_reg_write(ucb, UCB_ADC_CR, ucb->adc_cr | adc_channel | UCB_ADC_START);

        for (;;) {
                val = ucb1x00_reg_read(ucb, UCB_ADC_DATA);
                if (val & UCB_ADC_DAT_VAL)
                        break;
                /* yield to other processes */
                set_current_state(TASK_INTERRUPTIBLE);
                schedule_timeout(1);
        }

        return UCB_ADC_DAT(val);
}

/**
 *      ucb1x00_adc_disable - disable the ADC converter
 *      @ucb: UCB1x00 structure describing chip
 *
 *      Disable the ADC converter and release the ADC semaphore.
 */
void ucb1x00_adc_disable(struct ucb1x00 *ucb)
{
        ucb->adc_cr &= ~UCB_ADC_ENA;
        ucb1x00_reg_write(ucb, UCB_ADC_CR, ucb->adc_cr);
        ucb1x00_disable(ucb);

        up(&ucb->adc_sem);
}

/*
 * UCB1x00 Interrupt handling.
 *
 * The UCB1x00 can generate interrupts when the SIBCLK is stopped.
 * Since we need to read an internal register, we must re-enable
 * SIBCLK to talk to the chip.  We leave the clock running until
 * we have finished processing all interrupts from the chip.
 */
static irqreturn_t ucb1x00_irq(int irqnr, void *devid)
{
        struct ucb1x00 *ucb = devid;
        struct ucb1x00_irq *irq;
        unsigned int isr, i;

        ucb1x00_enable(ucb);
        isr = ucb1x00_reg_read(ucb, UCB_IE_STATUS);
        ucb1x00_reg_write(ucb, UCB_IE_CLEAR, isr);
        ucb1x00_reg_write(ucb, UCB_IE_CLEAR, 0);

        for (i = 0, irq = ucb->irq_handler; i < 16 && isr; i++, isr >>= 1, irq++)
                if (isr & 1 && irq->fn)
                        irq->fn(i, irq->devid);
        ucb1x00_disable(ucb);

        return IRQ_HANDLED;
}

/**
 *      ucb1x00_hook_irq - hook a UCB1x00 interrupt
 *      @ucb:   UCB1x00 structure describing chip
 *      @idx:   interrupt index
 *      @fn:    function to call when interrupt is triggered
 *      @devid: device id to pass to interrupt handler
 *
 *      Hook the specified interrupt.  You can only register one handler
 *      for each interrupt source.  The interrupt source is not enabled
 *      by this function; use ucb1x00_enable_irq instead.
 *
 *      Interrupt handlers will be called with other interrupts enabled.
 *
 *      Returns zero on success, or one of the following errors:
 *       -EINVAL if the interrupt index is invalid
 *       -EBUSY if the interrupt has already been hooked
 */
int ucb1x00_hook_irq(struct ucb1x00 *ucb, unsigned int idx, void (*fn)(int, void *), void *devid)
{
        struct ucb1x00_irq *irq;
        int ret = -EINVAL;

        if (idx < 16) {
                irq = ucb->irq_handler + idx;
                ret = -EBUSY;

                spin_lock_irq(&ucb->lock);
                if (irq->fn == NULL) {
                        irq->devid = devid;
                        irq->fn = fn;
                        ret = 0;
                }
                spin_unlock_irq(&ucb->lock);
        }
        return ret;
}

/**
 *      ucb1x00_enable_irq - enable an UCB1x00 interrupt source
 *      @ucb: UCB1x00 structure describing chip
 *      @idx: interrupt index
 *      @edges: interrupt edges to enable
 *
 *      Enable the specified interrupt to trigger on %UCB_RISING,
 *      %UCB_FALLING or both edges.  The interrupt should have been
 *      hooked by ucb1x00_hook_irq.
 */
void ucb1x00_enable_irq(struct ucb1x00 *ucb, unsigned int idx, int edges)
{
        unsigned long flags;

        if (idx < 16) {
                spin_lock_irqsave(&ucb->lock, flags);

                ucb1x00_enable(ucb);
                if (edges & UCB_RISING) {
                        ucb->irq_ris_enbl |= 1 << idx;
                        ucb1x00_reg_write(ucb, UCB_IE_RIS, ucb->irq_ris_enbl);
                }
                if (edges & UCB_FALLING) {
                        ucb->irq_fal_enbl |= 1 << idx;
                        ucb1x00_reg_write(ucb, UCB_IE_FAL, ucb->irq_fal_enbl);
                }
                ucb1x00_disable(ucb);
                spin_unlock_irqrestore(&ucb->lock, flags);
        }
}

/**
 *      ucb1x00_disable_irq - disable an UCB1x00 interrupt source
 *      @ucb: UCB1x00 structure describing chip
 *      @edges: interrupt edges to disable
 *
 *      Disable the specified interrupt triggering on the specified
 *      (%UCB_RISING, %UCB_FALLING or both) edges.
 */
void ucb1x00_disable_irq(struct ucb1x00 *ucb, unsigned int idx, int edges)
{
        unsigned long flags;

        if (idx < 16) {
                spin_lock_irqsave(&ucb->lock, flags);

                ucb1x00_enable(ucb);
                if (edges & UCB_RISING) {
                        ucb->irq_ris_enbl &= ~(1 << idx);
                        ucb1x00_reg_write(ucb, UCB_IE_RIS, ucb->irq_ris_enbl);
                }
                if (edges & UCB_FALLING) {
                        ucb->irq_fal_enbl &= ~(1 << idx);
                        ucb1x00_reg_write(ucb, UCB_IE_FAL, ucb->irq_fal_enbl);
                }
                ucb1x00_disable(ucb);
                spin_unlock_irqrestore(&ucb->lock, flags);
        }
}

/**
 *      ucb1x00_free_irq - disable and free the specified UCB1x00 interrupt
 *      @ucb: UCB1x00 structure describing chip
 *      @idx: interrupt index
 *      @devid: device id.
 *
 *      Disable the interrupt source and remove the handler.  devid must
 *      match the devid passed when hooking the interrupt.
 *
 *      Returns zero on success, or one of the following errors:
 *       -EINVAL if the interrupt index is invalid
 *       -ENOENT if devid does not match
 */
int ucb1x00_free_irq(struct ucb1x00 *ucb, unsigned int idx, void *devid)
{
        struct ucb1x00_irq *irq;
        int ret;

        if (idx >= 16)
                goto bad;

        irq = ucb->irq_handler + idx;
        ret = -ENOENT;

        spin_lock_irq(&ucb->lock);
        if (irq->devid == devid) {
                ucb->irq_ris_enbl &= ~(1 << idx);
                ucb->irq_fal_enbl &= ~(1 << idx);

                ucb1x00_enable(ucb);
                ucb1x00_reg_write(ucb, UCB_IE_RIS, ucb->irq_ris_enbl);
                ucb1x00_reg_write(ucb, UCB_IE_FAL, ucb->irq_fal_enbl);
                ucb1x00_disable(ucb);

                irq->fn = NULL;
                irq->devid = NULL;
                ret = 0;
        }
        spin_unlock_irq(&ucb->lock);
        return ret;

bad:
        printk(KERN_ERR "Freeing bad UCB1x00 irq %d\n", idx);
        return -EINVAL;
}

static int ucb1x00_add_dev(struct ucb1x00 *ucb, struct ucb1x00_driver *drv)
{
        struct ucb1x00_dev *dev;
        int ret = -ENOMEM;

        dev = kmalloc(sizeof(struct ucb1x00_dev), GFP_KERNEL);
        if (dev) {
                dev->ucb = ucb;
                dev->drv = drv;

                ret = drv->add(dev);

                if (ret == 0) {
                        list_add(&dev->dev_node, &ucb->devs);
                        list_add(&dev->drv_node, &drv->devs);
                } else {
                        kfree(dev);
                }
        }
        return ret;
}

static void ucb1x00_remove_dev(struct ucb1x00_dev *dev)
{
        dev->drv->remove(dev);
        list_del(&dev->dev_node);
        list_del(&dev->drv_node);
        kfree(dev);
}

/*
 * Try to probe our interrupt, rather than relying on lots of
 * hard-coded machine dependencies.  For reference, the expected
 * IRQ mappings are:
 *
 *      Machine         Default IRQ
 *      adsbitsy        IRQ_GPCIN4
 *      cerf            IRQ_GPIO_UCB1200_IRQ
 *      flexanet        IRQ_GPIO_GUI
 *      freebird        IRQ_GPIO_FREEBIRD_UCB1300_IRQ
 *      graphicsclient  ADS_EXT_IRQ(8)
 *      graphicsmaster  ADS_EXT_IRQ(8)
 *      lart            LART_IRQ_UCB1200
 *      omnimeter       IRQ_GPIO23
 *      pfs168          IRQ_GPIO_UCB1300_IRQ
 *      simpad          IRQ_GPIO_UCB1300_IRQ
 *      shannon         SHANNON_IRQ_GPIO_IRQ_CODEC
 *      yopy            IRQ_GPIO_UCB1200_IRQ
 */
static int ucb1x00_detect_irq(struct ucb1x00 *ucb)
{
        unsigned long mask;

        mask = probe_irq_on();
        if (!mask) {
                probe_irq_off(mask);
                return NO_IRQ;
        }

        /*
         * Enable the ADC interrupt.
         */
        ucb1x00_reg_write(ucb, UCB_IE_RIS, UCB_IE_ADC);
        ucb1x00_reg_write(ucb, UCB_IE_FAL, UCB_IE_ADC);
        ucb1x00_reg_write(ucb, UCB_IE_CLEAR, 0xffff);
        ucb1x00_reg_write(ucb, UCB_IE_CLEAR, 0);

        /*
         * Cause an ADC interrupt.
         */
        ucb1x00_reg_write(ucb, UCB_ADC_CR, UCB_ADC_ENA);
        ucb1x00_reg_write(ucb, UCB_ADC_CR, UCB_ADC_ENA | UCB_ADC_START);

        /*
         * Wait for the conversion to complete.
         */
        while ((ucb1x00_reg_read(ucb, UCB_ADC_DATA) & UCB_ADC_DAT_VAL) == 0);
        ucb1x00_reg_write(ucb, UCB_ADC_CR, 0);

        /*
         * Disable and clear interrupt.
         */
        ucb1x00_reg_write(ucb, UCB_IE_RIS, 0);
        ucb1x00_reg_write(ucb, UCB_IE_FAL, 0);
        ucb1x00_reg_write(ucb, UCB_IE_CLEAR, 0xffff);
        ucb1x00_reg_write(ucb, UCB_IE_CLEAR, 0);

        /*
         * Read triggered interrupt.
         */
        return probe_irq_off(mask);
}

static void ucb1x00_release(struct device *dev)
{
        struct ucb1x00 *ucb = classdev_to_ucb1x00(dev);
        kfree(ucb);
}

static struct class ucb1x00_class = {
        .name           = "ucb1x00",
        .dev_release    = ucb1x00_release,
};

static int ucb1x00_probe(struct mcp *mcp)
{
        struct ucb1x00 *ucb;
        struct ucb1x00_driver *drv;
        unsigned int id;
        int ret = -ENODEV;

        mcp_enable(mcp);
        id = mcp_reg_read(mcp, UCB_ID);

        if (id != UCB_ID_1200 && id != UCB_ID_1300 && id != UCB_ID_TC35143) {
                printk(KERN_WARNING "UCB1x00 ID not found: %04x\n", id);
                goto err_disable;
        }

        ucb = kzalloc(sizeof(struct ucb1x00), GFP_KERNEL);
        ret = -ENOMEM;
        if (!ucb)
                goto err_disable;


        ucb->dev.class = &ucb1x00_class;
        ucb->dev.parent = &mcp->attached_device;
        dev_set_name(&ucb->dev, "ucb1x00");

        spin_lock_init(&ucb->lock);
        spin_lock_init(&ucb->io_lock);
        sema_init(&ucb->adc_sem, 1);

        ucb->id  = id;
        ucb->mcp = mcp;
        ucb->irq = ucb1x00_detect_irq(ucb);
        if (ucb->irq == NO_IRQ) {
                printk(KERN_ERR "UCB1x00: IRQ probe failed\n");
                ret = -ENODEV;
                goto err_free;
        }

        ret = request_irq(ucb->irq, ucb1x00_irq, IRQF_TRIGGER_RISING,
                          "UCB1x00", ucb);
        if (ret) {
                printk(KERN_ERR "ucb1x00: unable to grab irq%d: %d\n",
                        ucb->irq, ret);
                goto err_free;
        }

        mcp_set_drvdata(mcp, ucb);

        ret = device_register(&ucb->dev);
        if (ret)
                goto err_irq;

        INIT_LIST_HEAD(&ucb->devs);
        mutex_lock(&ucb1x00_mutex);
        list_add(&ucb->node, &ucb1x00_devices);
        list_for_each_entry(drv, &ucb1x00_drivers, node) {
                ucb1x00_add_dev(ucb, drv);
        }
        mutex_unlock(&ucb1x00_mutex);
        goto out;

 err_irq:
        free_irq(ucb->irq, ucb);
 err_free:
        kfree(ucb);
 err_disable:
        mcp_disable(mcp);
 out:
        return ret;
}

static void ucb1x00_remove(struct mcp *mcp)
{
        struct ucb1x00 *ucb = mcp_get_drvdata(mcp);
        struct list_head *l, *n;

        mutex_lock(&ucb1x00_mutex);
        list_del(&ucb->node);
        list_for_each_safe(l, n, &ucb->devs) {
                struct ucb1x00_dev *dev = list_entry(l, struct ucb1x00_dev, dev_node);
                ucb1x00_remove_dev(dev);
        }
        mutex_unlock(&ucb1x00_mutex);

        free_irq(ucb->irq, ucb);
        device_unregister(&ucb->dev);
}

int ucb1x00_register_driver(struct ucb1x00_driver *drv)
{
        struct ucb1x00 *ucb;

        INIT_LIST_HEAD(&drv->devs);
        mutex_lock(&ucb1x00_mutex);
        list_add(&drv->node, &ucb1x00_drivers);
        list_for_each_entry(ucb, &ucb1x00_devices, node) {
                ucb1x00_add_dev(ucb, drv);
        }
        mutex_unlock(&ucb1x00_mutex);
        return 0;
}

void ucb1x00_unregister_driver(struct ucb1x00_driver *drv)
{
        struct list_head *n, *l;

        mutex_lock(&ucb1x00_mutex);
        list_del(&drv->node);
        list_for_each_safe(l, n, &drv->devs) {
                struct ucb1x00_dev *dev = list_entry(l, struct ucb1x00_dev, drv_node);
                ucb1x00_remove_dev(dev);
        }
        mutex_unlock(&ucb1x00_mutex);
}

static int ucb1x00_suspend(struct mcp *mcp, pm_message_t state)
{
        struct ucb1x00 *ucb = mcp_get_drvdata(mcp);
        struct ucb1x00_dev *dev;

        mutex_lock(&ucb1x00_mutex);
        list_for_each_entry(dev, &ucb->devs, dev_node) {
                if (dev->drv->suspend)
                        dev->drv->suspend(dev, state);
        }
        mutex_unlock(&ucb1x00_mutex);
        return 0;
}

static int ucb1x00_resume(struct mcp *mcp)
{
        struct ucb1x00 *ucb = mcp_get_drvdata(mcp);
        struct ucb1x00_dev *dev;

        mutex_lock(&ucb1x00_mutex);
        list_for_each_entry(dev, &ucb->devs, dev_node) {
                if (dev->drv->resume)
                        dev->drv->resume(dev);
        }
        mutex_unlock(&ucb1x00_mutex);
        return 0;
}

static struct mcp_driver ucb1x00_driver = {
        .drv            = {
                .name   = "ucb1x00",
        },
        .probe          = ucb1x00_probe,
        .remove         = ucb1x00_remove,
        .suspend        = ucb1x00_suspend,
        .resume         = ucb1x00_resume,
};

static int __init ucb1x00_init(void)
{
        int ret = class_register(&ucb1x00_class);
        if (ret == 0) {
                ret = mcp_driver_register(&ucb1x00_driver);
                if (ret)
                        class_unregister(&ucb1x00_class);
        }
        return ret;
}

static void __exit ucb1x00_exit(void)
{
        mcp_driver_unregister(&ucb1x00_driver);
        class_unregister(&ucb1x00_class);
}

module_init(ucb1x00_init);
module_exit(ucb1x00_exit);

EXPORT_SYMBOL(ucb1x00_io_set_dir);
EXPORT_SYMBOL(ucb1x00_io_write);
EXPORT_SYMBOL(ucb1x00_io_read);

EXPORT_SYMBOL(ucb1x00_adc_enable);
EXPORT_SYMBOL(ucb1x00_adc_read);
EXPORT_SYMBOL(ucb1x00_adc_disable);

EXPORT_SYMBOL(ucb1x00_hook_irq);
EXPORT_SYMBOL(ucb1x00_free_irq);
EXPORT_SYMBOL(ucb1x00_enable_irq);
EXPORT_SYMBOL(ucb1x00_disable_irq);

EXPORT_SYMBOL(ucb1x00_register_driver);
EXPORT_SYMBOL(ucb1x00_unregister_driver);

MODULE_AUTHOR("Russell King <rmk@arm.linux.org.uk>");
MODULE_DESCRIPTION("UCB1x00 core driver");
MODULE_LICENSE("GPL");