ucb1x00-core.c

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/*
 *  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 <asm/dma.h>
#include <asm/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