/*
   * max1111.c - +2.7V, Low-Power, Multichannel, Serial 8-bit ADCs
   *
   * Based on arch/arm/mach-pxa/corgi_ssp.c
   *
   * Copyright (C) 2004-2005 Richard Purdie
   *
   * Copyright (C) 2008 Marvell International Ltd.

   *	Eric Miao <eric.miao@marvell.com>

   *
   *  This program is free software; you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License version 2 as
   *  publishhed by the Free Software Foundation.
   */
  
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/err.h>
  #include <linux/hwmon.h>
  #include <linux/hwmon-sysfs.h>
  #include <linux/spi/spi.h>

  #include <linux/slab.h>

  
  #define MAX1111_TX_BUF_SIZE	1
  #define MAX1111_RX_BUF_SIZE	2
  
  /* MAX1111 Commands */
  #define MAX1111_CTRL_PD0      (1u << 0)
  #define MAX1111_CTRL_PD1      (1u << 1)
  #define MAX1111_CTRL_SGL      (1u << 2)
  #define MAX1111_CTRL_UNI      (1u << 3)
  #define MAX1111_CTRL_SEL_SH   (5)	/* NOTE: bit 4 is ignored */
  #define MAX1111_CTRL_STR      (1u << 7)
  
  struct max1111_data {
  	struct spi_device	*spi;
  	struct device		*hwmon_dev;
  	struct spi_message	msg;
  	struct spi_transfer	xfer[2];

  	uint8_t tx_buf[MAX1111_TX_BUF_SIZE];
  	uint8_t rx_buf[MAX1111_RX_BUF_SIZE];

  	struct mutex		drvdata_lock;
  	/* protect msg, xfer and buffers from multiple access */

  };
  
  static int max1111_read(struct device *dev, int channel)
  {
  	struct max1111_data *data = dev_get_drvdata(dev);
  	uint8_t v1, v2;
  	int err;

  	/* writing to drvdata struct is not thread safe, wait on mutex */
  	mutex_lock(&data->drvdata_lock);

  	data->tx_buf[0] = (channel << MAX1111_CTRL_SEL_SH) |
  		MAX1111_CTRL_PD0 | MAX1111_CTRL_PD1 |
  		MAX1111_CTRL_SGL | MAX1111_CTRL_UNI | MAX1111_CTRL_STR;
  
  	err = spi_sync(data->spi, &data->msg);
  	if (err < 0) {
  		dev_err(dev, "spi_sync failed with %d
  ", err);

  		mutex_unlock(&data->drvdata_lock);

  		return err;
  	}
  
  	v1 = data->rx_buf[0];
  	v2 = data->rx_buf[1];

  	mutex_unlock(&data->drvdata_lock);

  	if ((v1 & 0xc0) || (v2 & 0x3f))
  		return -EINVAL;
  
  	return (v1 << 2) | (v2 >> 6);
  }

  #ifdef CONFIG_SHARPSL_PM
  static struct max1111_data *the_max1111;
  
  int max1111_read_channel(int channel)
  {
  	return max1111_read(&the_max1111->spi->dev, channel);
  }
  EXPORT_SYMBOL(max1111_read_channel);
  #endif

  /*
   * NOTE: SPI devices do not have a default 'name' attribute, which is
   * likely to be used by hwmon applications to distinguish between
   * different devices, explicitly add a name attribute here.
   */
  static ssize_t show_name(struct device *dev,
  			 struct device_attribute *attr, char *buf)
  {
  	return sprintf(buf, "max1111
  ");
  }
  
  static ssize_t show_adc(struct device *dev,
  			struct device_attribute *attr, char *buf)
  {
  	int channel = to_sensor_dev_attr(attr)->index;
  	int ret;
  
  	ret = max1111_read(dev, channel);
  	if (ret < 0)
  		return ret;

  	/* assume the reference voltage to be 2.048V, with an 8-bit sample,
  	 * the LSB weight is 8mV
  	 */
  	return sprintf(buf, "%d
  ", ret * 8);

  }
  
  #define MAX1111_ADC_ATTR(_id)		\

  	SENSOR_DEVICE_ATTR(in##_id##_input, S_IRUGO, show_adc, NULL, _id)

  
  static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
  static MAX1111_ADC_ATTR(0);
  static MAX1111_ADC_ATTR(1);
  static MAX1111_ADC_ATTR(2);
  static MAX1111_ADC_ATTR(3);
  
  static struct attribute *max1111_attributes[] = {
  	&dev_attr_name.attr,

  	&sensor_dev_attr_in0_input.dev_attr.attr,
  	&sensor_dev_attr_in1_input.dev_attr.attr,
  	&sensor_dev_attr_in2_input.dev_attr.attr,
  	&sensor_dev_attr_in3_input.dev_attr.attr,

  	NULL,
  };
  
  static const struct attribute_group max1111_attr_group = {
  	.attrs	= max1111_attributes,
  };

  static int __devinit setup_transfer(struct max1111_data *data)

  {
  	struct spi_message *m;
  	struct spi_transfer *x;

  	m = &data->msg;
  	x = &data->xfer[0];
  
  	spi_message_init(m);
  
  	x->tx_buf = &data->tx_buf[0];

  	x->len = MAX1111_TX_BUF_SIZE;

  	spi_message_add_tail(x, m);
  
  	x++;
  	x->rx_buf = &data->rx_buf[0];

  	x->len = MAX1111_RX_BUF_SIZE;

  	spi_message_add_tail(x, m);
  
  	return 0;
  }
  
  static int __devinit max1111_probe(struct spi_device *spi)
  {
  	struct max1111_data *data;
  	int err;
  
  	spi->bits_per_word = 8;
  	spi->mode = SPI_MODE_0;
  	err = spi_setup(spi);
  	if (err < 0)
  		return err;
  
  	data = kzalloc(sizeof(struct max1111_data), GFP_KERNEL);
  	if (data == NULL) {
  		dev_err(&spi->dev, "failed to allocate memory
  ");
  		return -ENOMEM;
  	}
  
  	err = setup_transfer(data);
  	if (err)
  		goto err_free_data;

  	mutex_init(&data->drvdata_lock);

  	data->spi = spi;
  	spi_set_drvdata(spi, data);
  
  	err = sysfs_create_group(&spi->dev.kobj, &max1111_attr_group);
  	if (err) {
  		dev_err(&spi->dev, "failed to create attribute group
  ");

  		goto err_free_data;

  	}
  
  	data->hwmon_dev = hwmon_device_register(&spi->dev);
  	if (IS_ERR(data->hwmon_dev)) {
  		dev_err(&spi->dev, "failed to create hwmon device
  ");
  		err = PTR_ERR(data->hwmon_dev);
  		goto err_remove;
  	}

  #ifdef CONFIG_SHARPSL_PM
  	the_max1111 = data;
  #endif

  	return 0;
  
  err_remove:
  	sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);

  err_free_data:
  	kfree(data);
  	return err;
  }
  
  static int __devexit max1111_remove(struct spi_device *spi)
  {
  	struct max1111_data *data = spi_get_drvdata(spi);
  
  	hwmon_device_unregister(data->hwmon_dev);
  	sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);

  	mutex_destroy(&data->drvdata_lock);

  	kfree(data);
  	return 0;
  }
  
  static struct spi_driver max1111_driver = {
  	.driver		= {
  		.name	= "max1111",
  		.owner	= THIS_MODULE,
  	},
  	.probe		= max1111_probe,
  	.remove		= __devexit_p(max1111_remove),
  };
  
  static int __init max1111_init(void)
  {
  	return spi_register_driver(&max1111_driver);
  }
  module_init(max1111_init);
  
  static void __exit max1111_exit(void)
  {
  	spi_unregister_driver(&max1111_driver);
  }
  module_exit(max1111_exit);
  
  MODULE_AUTHOR("Eric Miao <eric.miao@marvell.com>");
  MODULE_DESCRIPTION("MAX1111 ADC Driver");
  MODULE_LICENSE("GPL");

  MODULE_ALIAS("spi:max1111");