/* NXP PCF50633 ADC Driver
   *
   * (C) 2006-2008 by Openmoko, Inc.
   * Author: Balaji Rao <balajirrao@openmoko.org>
   * All rights reserved.
   *
   * Broken down from monstrous PCF50633 driver mainly by
   * Harald Welte, Andy Green and Werner Almesberger
   *
   *  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.
   *
   *  NOTE: This driver does not yet support subtractive ADC mode, which means
   *  you can do only one measurement per read request.
   */
  
  #include <linux/kernel.h>

  #include <linux/slab.h>

  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/device.h>
  #include <linux/platform_device.h>
  #include <linux/completion.h>
  
  #include <linux/mfd/pcf50633/core.h>
  #include <linux/mfd/pcf50633/adc.h>
  
  struct pcf50633_adc_request {
  	int mux;
  	int avg;

  	void (*callback)(struct pcf50633 *, void *, int);
  	void *callback_param;

  };

  struct pcf50633_adc_sync_request {
  	int result;

  	struct completion completion;

  };
  
  #define PCF50633_MAX_ADC_FIFO_DEPTH 8
  
  struct pcf50633_adc {
  	struct pcf50633 *pcf;
  
  	/* Private stuff */
  	struct pcf50633_adc_request *queue[PCF50633_MAX_ADC_FIFO_DEPTH];
  	int queue_head;
  	int queue_tail;
  	struct mutex queue_mutex;
  };
  
  static inline struct pcf50633_adc *__to_adc(struct pcf50633 *pcf)
  {
  	return platform_get_drvdata(pcf->adc_pdev);
  }
  
  static void adc_setup(struct pcf50633 *pcf, int channel, int avg)
  {
  	channel &= PCF50633_ADCC1_ADCMUX_MASK;
  
  	/* kill ratiometric, but enable ACCSW biasing */
  	pcf50633_reg_write(pcf, PCF50633_REG_ADCC2, 0x00);
  	pcf50633_reg_write(pcf, PCF50633_REG_ADCC3, 0x01);
  
  	/* start ADC conversion on selected channel */
  	pcf50633_reg_write(pcf, PCF50633_REG_ADCC1, channel | avg |
  		    PCF50633_ADCC1_ADCSTART | PCF50633_ADCC1_RES_10BIT);
  }
  
  static void trigger_next_adc_job_if_any(struct pcf50633 *pcf)
  {
  	struct pcf50633_adc *adc = __to_adc(pcf);
  	int head;

  	head = adc->queue_head;

  	if (!adc->queue[head])

  		return;

  
  	adc_setup(pcf, adc->queue[head]->mux, adc->queue[head]->avg);
  }
  
  static int
  adc_enqueue_request(struct pcf50633 *pcf, struct pcf50633_adc_request *req)
  {
  	struct pcf50633_adc *adc = __to_adc(pcf);
  	int head, tail;
  
  	mutex_lock(&adc->queue_mutex);
  
  	head = adc->queue_head;
  	tail = adc->queue_tail;
  
  	if (adc->queue[tail]) {
  		mutex_unlock(&adc->queue_mutex);

  		dev_err(pcf->dev, "ADC queue is full, dropping request
  ");

  		return -EBUSY;
  	}
  
  	adc->queue[tail] = req;

  	if (head == tail)
  		trigger_next_adc_job_if_any(pcf);

  	adc->queue_tail = (tail + 1) & (PCF50633_MAX_ADC_FIFO_DEPTH - 1);
  
  	mutex_unlock(&adc->queue_mutex);

  	return 0;
  }

  static void pcf50633_adc_sync_read_callback(struct pcf50633 *pcf, void *param,
  	int result)

  {

  	struct pcf50633_adc_sync_request *req = param;

  
  	req->result = result;
  	complete(&req->completion);
  }
  
  int pcf50633_adc_sync_read(struct pcf50633 *pcf, int mux, int avg)
  {

  	struct pcf50633_adc_sync_request req;
  	int ret;

  	init_completion(&req.completion);

  	ret = pcf50633_adc_async_read(pcf, mux, avg,
  		pcf50633_adc_sync_read_callback, &req);
  	if (ret)
  		return ret;

  	wait_for_completion(&req.completion);

  	return req.result;

  }
  EXPORT_SYMBOL_GPL(pcf50633_adc_sync_read);
  
  int pcf50633_adc_async_read(struct pcf50633 *pcf, int mux, int avg,
  			     void (*callback)(struct pcf50633 *, void *, int),
  			     void *callback_param)
  {
  	struct pcf50633_adc_request *req;
  
  	/* req is freed when the result is ready, in interrupt handler */
  	req = kmalloc(sizeof(*req), GFP_KERNEL);
  	if (!req)
  		return -ENOMEM;
  
  	req->mux = mux;
  	req->avg = avg;
  	req->callback = callback;
  	req->callback_param = callback_param;

  	return adc_enqueue_request(pcf, req);

  }
  EXPORT_SYMBOL_GPL(pcf50633_adc_async_read);
  
  static int adc_result(struct pcf50633 *pcf)
  {
  	u8 adcs1, adcs3;
  	u16 result;
  
  	adcs1 = pcf50633_reg_read(pcf, PCF50633_REG_ADCS1);
  	adcs3 = pcf50633_reg_read(pcf, PCF50633_REG_ADCS3);
  	result = (adcs1 << 2) | (adcs3 & PCF50633_ADCS3_ADCDAT1L_MASK);
  
  	dev_dbg(pcf->dev, "adc result = %d
  ", result);
  
  	return result;
  }
  
  static void pcf50633_adc_irq(int irq, void *data)
  {
  	struct pcf50633_adc *adc = data;
  	struct pcf50633 *pcf = adc->pcf;
  	struct pcf50633_adc_request *req;

  	int head, res;

  
  	mutex_lock(&adc->queue_mutex);
  	head = adc->queue_head;
  
  	req = adc->queue[head];
  	if (WARN_ON(!req)) {
  		dev_err(pcf->dev, "pcf50633-adc irq: ADC queue empty!
  ");
  		mutex_unlock(&adc->queue_mutex);
  		return;
  	}
  	adc->queue[head] = NULL;
  	adc->queue_head = (head + 1) &
  				      (PCF50633_MAX_ADC_FIFO_DEPTH - 1);

  	res = adc_result(pcf);
  	trigger_next_adc_job_if_any(pcf);

  	mutex_unlock(&adc->queue_mutex);

  	req->callback(pcf, req->callback_param, res);

  	kfree(req);

  }
  
  static int __devinit pcf50633_adc_probe(struct platform_device *pdev)
  {

  	struct pcf50633_adc *adc;
  
  	adc = kzalloc(sizeof(*adc), GFP_KERNEL);
  	if (!adc)
  		return -ENOMEM;

  	adc->pcf = dev_to_pcf50633(pdev->dev.parent);

  	platform_set_drvdata(pdev, adc);

  	pcf50633_register_irq(adc->pcf, PCF50633_IRQ_ADCRDY,

  					pcf50633_adc_irq, adc);
  
  	mutex_init(&adc->queue_mutex);
  
  	return 0;
  }
  
  static int __devexit pcf50633_adc_remove(struct platform_device *pdev)
  {
  	struct pcf50633_adc *adc = platform_get_drvdata(pdev);
  	int i, head;
  
  	pcf50633_free_irq(adc->pcf, PCF50633_IRQ_ADCRDY);
  
  	mutex_lock(&adc->queue_mutex);
  	head = adc->queue_head;
  
  	if (WARN_ON(adc->queue[head]))
  		dev_err(adc->pcf->dev,
  			"adc driver removed with request pending
  ");
  
  	for (i = 0; i < PCF50633_MAX_ADC_FIFO_DEPTH; i++)
  		kfree(adc->queue[i]);
  
  	mutex_unlock(&adc->queue_mutex);
  	kfree(adc);
  
  	return 0;
  }
  
  static struct platform_driver pcf50633_adc_driver = {
  	.driver = {
  		.name = "pcf50633-adc",
  	},
  	.probe = pcf50633_adc_probe,
  	.remove = __devexit_p(pcf50633_adc_remove),
  };

  module_platform_driver(pcf50633_adc_driver);

  
  MODULE_AUTHOR("Balaji Rao <balajirrao@openmoko.org>");
  MODULE_DESCRIPTION("PCF50633 adc driver");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("platform:pcf50633-adc");