/*
   * 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>
  
  enum chips { max1110, max1111, max1112, max1113 };
  
  #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 MAX1110_CTRL_SEL_SH   (4)
  #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 */
  	int			sel_sh;
  	int			lsb;
  };
  
  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 << data->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, "%s
  ", to_spi_device(dev)->modalias);
  }
  
  static ssize_t show_adc(struct device *dev,
  			struct device_attribute *attr, char *buf)
  {
  	struct max1111_data *data = dev_get_drvdata(dev);
  	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 or 4.096V, with an 8-bit
  	 * sample. The LSB weight is 8mV or 16mV depending on the chip type.
  	 */
  	return sprintf(buf, "%d
  ", ret * data->lsb);
  }
  
  #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 MAX1111_ADC_ATTR(4);
  static MAX1111_ADC_ATTR(5);
  static MAX1111_ADC_ATTR(6);
  static MAX1111_ADC_ATTR(7);
  
  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 struct attribute *max1110_attributes[] = {
  	&sensor_dev_attr_in4_input.dev_attr.attr,
  	&sensor_dev_attr_in5_input.dev_attr.attr,
  	&sensor_dev_attr_in6_input.dev_attr.attr,
  	&sensor_dev_attr_in7_input.dev_attr.attr,
  	NULL,
  };
  
  static const struct attribute_group max1110_attr_group = {
  	.attrs	= max1110_attributes,
  };
  
  static int 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 max1111_probe(struct spi_device *spi)
  {
  	enum chips chip = spi_get_device_id(spi)->driver_data;
  	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 = devm_kzalloc(&spi->dev, sizeof(struct max1111_data), GFP_KERNEL);
  	if (data == NULL) {
  		dev_err(&spi->dev, "failed to allocate memory
  ");
  		return -ENOMEM;
  	}
  
  	switch (chip) {
  	case max1110:
  		data->lsb = 8;
  		data->sel_sh = MAX1110_CTRL_SEL_SH;
  		break;
  	case max1111:
  		data->lsb = 8;
  		data->sel_sh = MAX1111_CTRL_SEL_SH;
  		break;
  	case max1112:
  		data->lsb = 16;
  		data->sel_sh = MAX1110_CTRL_SEL_SH;
  		break;
  	case max1113:
  		data->lsb = 16;
  		data->sel_sh = MAX1111_CTRL_SEL_SH;
  		break;
  	}
  	err = setup_transfer(data);
  	if (err)
  		return err;
  
  	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
  ");
  		return err;
  	}
  	if (chip == max1110 || chip == max1112) {
  		err = sysfs_create_group(&spi->dev.kobj, &max1110_attr_group);
  		if (err) {
  			dev_err(&spi->dev,
  				"failed to create extended attribute group
  ");
  			goto err_remove;
  		}
  	}
  
  	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, &max1110_attr_group);
  	sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);
  	return err;
  }
  
  static int 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, &max1110_attr_group);
  	sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);
  	mutex_destroy(&data->drvdata_lock);
  	return 0;
  }
  
  static const struct spi_device_id max1111_ids[] = {
  	{ "max1110", max1110 },
  	{ "max1111", max1111 },
  	{ "max1112", max1112 },
  	{ "max1113", max1113 },
  	{ },
  };
  MODULE_DEVICE_TABLE(spi, max1111_ids);
  
  static struct spi_driver max1111_driver = {
  	.driver		= {
  		.name	= "max1111",
  		.owner	= THIS_MODULE,
  	},
  	.id_table	= max1111_ids,
  	.probe		= max1111_probe,
  	.remove		= max1111_remove,
  };
  
  module_spi_driver(max1111_driver);
  
  MODULE_AUTHOR("Eric Miao <eric.miao@marvell.com>");
  MODULE_DESCRIPTION("MAX1110/MAX1111/MAX1112/MAX1113 ADC Driver");
  MODULE_LICENSE("GPL");