/*
 * ina230.c - driver for TI INA230 current / power monitor sensor
 * (also compatible with TI INA226)
 *
 *
 * Copyright (c) 2011, NVIDIA Corporation.
 *
 * 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; version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 *
 * The INA230(/INA226) is a sensor chip made by Texas Instruments. It measures
 * power, voltage and current on a power rail and provides an alert on
 * over voltage/power
 * Complete datasheet can be obtained from ti.com
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/sysfs.h>
#include <linux/kobject.h>
#include <linux/hrtimer.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/mutex.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/gpio.h>
#include <linux/device.h>
#include <linux/sysdev.h>
#include <linux/platform_data/ina230.h>
#include <linux/init.h>
#include <linux/hwmon-sysfs.h>
#include <linux/hwmon.h>
#include <linux/cpu.h>


#define DRIVER_NAME "ina230"
#define MEASURE_BUS_VOLT 0

/* ina230 (/ ina226)register offsets */
#define INA230_CONFIG	0
#define INA230_SHUNT	1
#define INA230_VOLTAGE	2
#define INA230_POWER	3
#define INA230_CURRENT	4
#define INA230_CAL	5
#define INA230_MASK	6
#define INA230_ALERT	7

/*
Config register for ina230 (/ ina226):
D15|D14 D13 D12|D11 D10 D09|D08 D07 D06|D05 D04 D03|D02 D01 D00
rst|-   -   -  |AVG        |Vbus_CT    |Vsh_CT     |MODE
*/
#define INA230_RESET		(1 << 15)
#define INA230_AVG		(0 << 9) /* 0 Averages */
#define INA230_VBUS_CT		(0 << 6) /* Vbus 140us conversion time */
#define INA230_VSH_CT		(0 << 3) /* Vshunt 140us conversion time */

#if MEASURE_BUS_VOLT
#define INA230_CONT_MODE	5	/* Continuous Shunt measurement */
#define INA230_TRIG_MODE	1	/* Triggered Shunt measurement */
#else
#define INA230_CONT_MODE	7	/* Continuous Bus and shunt measure */
#define INA230_TRIG_MODE	3	/* Triggered Bus and shunt measure */
#endif

#define INA230_POWER_DOWN	0
#define INA230_CONT_CONFIG	(INA230_AVG | INA230_VBUS_CT | \
				 INA230_VSH_CT | INA230_CONT_MODE)
#define INA230_TRIG_CONFIG	(INA230_AVG | INA230_VBUS_CT | \
				 INA230_VSH_CT | INA230_TRIG_MODE)

/*
Mask register for ina230 (/ina 226):
D15|D14|D13|D12|D11 D10 D09 D08 D07 D06 D05 D04 D03 D02 D01 D00
SOL|SUL|BOL|BUL|POL|CVR|-   -   -   -   -  |AFF|CVF|OVF|APO|LEN
*/
#define INA230_MASK_SOL		(1 << 15)
#define INA230_MASK_SUL		(1 << 14)


struct ina230_data {
	struct device *hwmon_dev;
	struct i2c_client *client;
	struct ina230_platform_data *pdata;
	struct mutex mutex;
	bool running;
	struct notifier_block nb;
};


/* bus voltage resolution: 1.25mv */
#define busv_register_to_mv(x) (((x) * 5) >> 2)

/* shunt voltage resolution: 2.5uv */
#define shuntv_register_to_uv(x) (((x) * 5) >> 1)
#define uv_to_alert_register(x) (((x) << 1) / 5)



static s32 ensure_enabled_start(struct i2c_client *client)
{
	struct ina230_data *data = i2c_get_clientdata(client);
	int retval;

	if (data->running)
		return 0;

	retval = i2c_smbus_write_word_data(client, INA230_CONFIG,
				    __constant_cpu_to_be16(INA230_TRIG_CONFIG));
	if (retval < 0)
		dev_err(&client->dev, "config data write failed sts: 0x%x\n",
			retval);

	return retval;
}


static void ensure_enabled_end(struct i2c_client *client)
{
	struct ina230_data *data = i2c_get_clientdata(client);
	int retval;

	if (data->running)
		return;

	retval = i2c_smbus_write_word_data(client, INA230_CONFIG,
				     __constant_cpu_to_be16(INA230_POWER_DOWN));
	if (retval < 0)
		dev_err(&client->dev, "power down failure sts: 0x%x\n",
			retval);
}


static s32 __locked_power_down_ina230(struct i2c_client *client)
{
	s32 retval;
	struct ina230_data *data = i2c_get_clientdata(client);

	if (!data->running)
		return 0;

	retval = i2c_smbus_write_word_data(client, INA230_MASK, 0);
	if (retval < 0)
		dev_err(&client->dev, "mask write failure sts: 0x%x\n",
			retval);

	retval = i2c_smbus_write_word_data(client, INA230_CONFIG,
				     __constant_cpu_to_be16(INA230_POWER_DOWN));
	if (retval < 0)
		dev_err(&client->dev, "power down failure sts: 0x%x\n",
			retval);

	data->running = false;

	return retval;
}


static s32 power_down_ina230(struct i2c_client *client)
{
	s32 retval;
	struct ina230_data *data = i2c_get_clientdata(client);

	mutex_lock(&data->mutex);
	retval = __locked_power_down_ina230(client);
	mutex_unlock(&data->mutex);

	return retval;
}


static s32 __locked_start_current_mon(struct i2c_client *client)
{
	s32 retval;
	s16 shunt_limit;
	s16 alert_mask;
	struct ina230_data *data = i2c_get_clientdata(client);

	if (!data->pdata->current_threshold) {
		dev_err(&client->dev, "no current threshold specified\n");
		return -EINVAL;
	}

	retval = i2c_smbus_write_word_data(client, INA230_CONFIG,
				    __constant_cpu_to_be16(INA230_CONT_CONFIG));
	if (retval < 0) {
		dev_err(&client->dev, "config data write failed sts: 0x%x\n",
			retval);
		return retval;
	}

	shunt_limit = uv_to_alert_register(data->pdata->resistor *
					   data->pdata->current_threshold);

	retval = i2c_smbus_write_word_data(client, INA230_ALERT,
					   cpu_to_be16(shunt_limit));
	if (retval < 0) {
		dev_err(&client->dev, "alert data write failed sts: 0x%x\n",
			retval);
		return retval;
	}

	alert_mask = shunt_limit >= 0 ? INA230_MASK_SOL : INA230_MASK_SUL;
	retval = i2c_smbus_write_word_data(client, INA230_MASK,
					   cpu_to_be16(alert_mask));
	if (retval < 0) {
		dev_err(&client->dev, "mask data write failed sts: 0x%x\n",
			retval);
		return retval;
	}

	data->running = true;

	return 0;
}


static void __locked_evaluate_state(struct i2c_client *client)
{
	struct ina230_data *data = i2c_get_clientdata(client);
	int cpus = num_online_cpus();

	if (data->running) {
		if (cpus < data->pdata->min_cores_online ||
		    !data->pdata->current_threshold)
			__locked_power_down_ina230(client);
	} else {
		if (cpus >= data->pdata->min_cores_online &&
		    data->pdata->current_threshold)
			__locked_start_current_mon(client);
	}
}


static void evaluate_state(struct i2c_client *client)
{
	struct ina230_data *data = i2c_get_clientdata(client);

	mutex_lock(&data->mutex);
	__locked_evaluate_state(client);
	mutex_unlock(&data->mutex);
}


static s32 show_rail_name(struct device *dev,
			  struct device_attribute *attr,
			  char *buf)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct ina230_data *data = i2c_get_clientdata(client);
	return sprintf(buf, "%s\n", data->pdata->rail_name);
}


static s32 show_current_threshold(struct device *dev,
				  struct device_attribute *attr,
				  char *buf)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct ina230_data *data = i2c_get_clientdata(client);
	return sprintf(buf, "%d mA\n", data->pdata->current_threshold);
}


static s32 set_current_threshold(struct device *dev,
				 struct device_attribute *attr,
				 const char *buf, size_t count)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct ina230_data *data = i2c_get_clientdata(client);
	s32 retval;

	mutex_lock(&data->mutex);

	if (strict_strtol(buf, 10, (long *)&(data->pdata->current_threshold))) {
		retval = -EINVAL;
		goto out;
	}

	if (data->pdata->current_threshold) {
		if (data->running) {
			/* force restart */
			retval = __locked_start_current_mon(client);
		} else {
			__locked_evaluate_state(client);
			retval = 0;
		}
	} else {
		retval = __locked_power_down_ina230(client);
	}

out:
	mutex_unlock(&data->mutex);
	if (retval >= 0)
		return count;
	return retval;
}




#if MEASURE_BUS_VOLT
static s32 show_bus_voltage(struct device *dev,
			struct device_attribute *attr,
			char *buf)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct ina230_data *data = i2c_get_clientdata(client);
	s32 voltage_mV;
	int retval;

	mutex_lock(&data->mutex);
	retval = ensure_enabled_start(client);
	if (retval < 0) {
		mutex_unlock(&data->mutex);
		return retval;
	}

	/* getting voltage readings in milli volts*/
	voltage_mV =
		(s16)be16_to_cpu(i2c_smbus_read_word_data(client,
							  INA230_VOLTAGE));

	ensure_enabled_end(client);
	mutex_unlock(&data->mutex);

	if (voltage_mV < 0) {
		dev_err(dev, "%s: failed\n", __func__);
		return -1;
	}

	voltage_mV = busv_register_to_mv(voltage_mV);

	return sprintf(buf, "%d mV\n", voltage_mV);
}
#endif




static s32 show_shunt_voltage(struct device *dev,
			struct device_attribute *attr,
			char *buf)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct ina230_data *data = i2c_get_clientdata(client);
	s32 voltage_uV;
	int retval;

	mutex_lock(&data->mutex);
	retval = ensure_enabled_start(client);
	if (retval < 0) {
		mutex_unlock(&data->mutex);
		return retval;
	}

	voltage_uV =
		(s16)be16_to_cpu(i2c_smbus_read_word_data(client,
							  INA230_SHUNT));

	ensure_enabled_end(client);
	mutex_unlock(&data->mutex);

	voltage_uV = shuntv_register_to_uv(voltage_uV);

	return sprintf(buf, "%d uV\n", voltage_uV);
}


static s32 show_current(struct device *dev,
			struct device_attribute *attr,
			char *buf)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct ina230_data *data = i2c_get_clientdata(client);
	s32 voltage_uV;
	s32 current_mA;
	int retval;

	mutex_lock(&data->mutex);
	retval = ensure_enabled_start(client);
	if (retval < 0) {
		mutex_unlock(&data->mutex);
		return retval;
	}

	voltage_uV =
		(s16)be16_to_cpu(i2c_smbus_read_word_data(client,
							  INA230_SHUNT));

	ensure_enabled_end(client);
	mutex_unlock(&data->mutex);

	voltage_uV = shuntv_register_to_uv(voltage_uV);
	current_mA = voltage_uV / data->pdata->resistor;

	return sprintf(buf, "%d mA\n", current_mA);
}


static int ina230_hotplug_notify(struct notifier_block *nb, unsigned long event,
				void *hcpu)
{
	struct ina230_data *data = container_of(nb, struct ina230_data,
						nb);
	struct i2c_client *client = data->client;

	if (event == CPU_ONLINE || event == CPU_DEAD)
		evaluate_state(client);

	return 0;
}



static struct sensor_device_attribute ina230[] = {
	SENSOR_ATTR(rail_name, S_IRUGO, show_rail_name, NULL, 0),
	SENSOR_ATTR(current_threshold, S_IWUSR | S_IRUGO,
		    show_current_threshold, set_current_threshold, 0),
	SENSOR_ATTR(shuntvolt1_input, S_IRUGO, show_shunt_voltage, NULL, 0),
	SENSOR_ATTR(current1_input, S_IRUGO, show_current, NULL, 0),
#if MEASURE_BUS_VOLT
	SENSOR_ATTR(busvolt1_input, S_IRUGO, show_bus_voltage, NULL, 0),
#endif
};


static int __devinit ina230_probe(struct i2c_client *client,
				const struct i2c_device_id *id)
{
	struct ina230_data *data;
	int err;
	u8 i;

	data = devm_kzalloc(&client->dev, sizeof(struct ina230_data),
			    GFP_KERNEL);
	if (!data) {
		err = -ENOMEM;
		goto exit;
	}

	i2c_set_clientdata(client, data);
	data->pdata = client->dev.platform_data;
	data->running = false;
	data->nb.notifier_call = ina230_hotplug_notify;
	data->client = client;
	mutex_init(&data->mutex);

	err = i2c_smbus_write_word_data(client, INA230_CONFIG,
		__constant_cpu_to_be16(INA230_RESET));
	if (err < 0) {
		dev_err(&client->dev, "ina230 reset failure status: 0x%x\n",
			err);
		goto exit;
	}

	for (i = 0; i < ARRAY_SIZE(ina230); i++) {
		err = device_create_file(&client->dev, &ina230[i].dev_attr);
		if (err) {
			dev_err(&client->dev, "device_create_file failed.\n");
			goto exit_remove;
		}
	}

	data->hwmon_dev = hwmon_device_register(&client->dev);
	if (IS_ERR(data->hwmon_dev)) {
		err = PTR_ERR(data->hwmon_dev);
		goto exit_remove;
	}

	register_hotcpu_notifier(&(data->nb));

	evaluate_state(client);

	return 0;

exit_remove:
	for (i = 0; i < ARRAY_SIZE(ina230); i++)
		device_remove_file(&client->dev, &ina230[i].dev_attr);
exit:
	return err;
}


static int __devexit ina230_remove(struct i2c_client *client)
{
	u8 i;
	struct ina230_data *data = i2c_get_clientdata(client);
	unregister_hotcpu_notifier(&(data->nb));
	power_down_ina230(client);
	hwmon_device_unregister(data->hwmon_dev);
	for (i = 0; i < ARRAY_SIZE(ina230); i++)
		device_remove_file(&client->dev, &ina230[i].dev_attr);
	return 0;
}


static int ina230_suspend(struct i2c_client *client)
{
	return power_down_ina230(client);
}


static int ina230_resume(struct i2c_client *client)
{
	evaluate_state(client);
	return 0;
}


static const struct i2c_device_id ina230_id[] = {
	{DRIVER_NAME, 0 },
	{}
};
MODULE_DEVICE_TABLE(i2c, ina230_id);


static struct i2c_driver ina230_driver = {
	.class		= I2C_CLASS_HWMON,
	.driver = {
		.name	= DRIVER_NAME,
	},
	.probe		= ina230_probe,
	.remove		= __devexit_p(ina230_remove),
	.suspend	= ina230_suspend,
	.resume		= ina230_resume,
	.id_table	= ina230_id,
};


static int __init ina230_init(void)
{
	return i2c_add_driver(&ina230_driver);
}


static void __exit ina230_exit(void)
{
	i2c_del_driver(&ina230_driver);
}


module_init(ina230_init);
module_exit(ina230_exit);
MODULE_LICENSE("GPL");