drivers/hwmon/ltc4222.c

Source file repositories/reference/linux-study-clean/drivers/hwmon/ltc4222.c

File Facts

System
Linux kernel
Corpus path
drivers/hwmon/ltc4222.c
Extension
.c
Size
6201 bytes
Lines
222
Domain
Driver Families
Bucket
drivers/hwmon
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Driver for Linear Technology LTC4222 Dual Hot Swap controller
 *
 * Copyright (c) 2014 Guenter Roeck
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/bitops.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/jiffies.h>
#include <linux/regmap.h>

/* chip registers */

#define LTC4222_CONTROL1	0xd0
#define LTC4222_ALERT1		0xd1
#define LTC4222_STATUS1		0xd2
#define LTC4222_FAULT1		0xd3
#define LTC4222_CONTROL2	0xd4
#define LTC4222_ALERT2		0xd5
#define LTC4222_STATUS2		0xd6
#define LTC4222_FAULT2		0xd7
#define LTC4222_SOURCE1		0xd8
#define LTC4222_SOURCE2		0xda
#define LTC4222_ADIN1		0xdc
#define LTC4222_ADIN2		0xde
#define LTC4222_SENSE1		0xe0
#define LTC4222_SENSE2		0xe2
#define LTC4222_ADC_CONTROL	0xe4

/*
 * Fault register bits
 */
#define FAULT_OV	BIT(0)
#define FAULT_UV	BIT(1)
#define FAULT_OC	BIT(2)
#define FAULT_POWER_BAD	BIT(3)
#define FAULT_FET_BAD	BIT(5)

/* Return the voltage from the given register in mV or mA */
static int ltc4222_get_value(struct device *dev, u8 reg)
{
	struct regmap *regmap = dev_get_drvdata(dev);
	unsigned int val;
	u8 buf[2];
	int ret;

	ret = regmap_bulk_read(regmap, reg, buf, 2);
	if (ret < 0)
		return ret;

	val = ((buf[0] << 8) + buf[1]) >> 6;

	switch (reg) {
	case LTC4222_ADIN1:
	case LTC4222_ADIN2:
		/* 1.25 mV resolution. Convert to mV. */
		val = DIV_ROUND_CLOSEST(val * 5, 4);
		break;
	case LTC4222_SOURCE1:
	case LTC4222_SOURCE2:
		/* 31.25 mV resolution. Convert to mV. */
		val = DIV_ROUND_CLOSEST(val * 125, 4);
		break;
	case LTC4222_SENSE1:
	case LTC4222_SENSE2:
		/*
		 * 62.5 uV resolution. Convert to current as measured with
		 * an 1 mOhm sense resistor, in mA. If a different sense
		 * resistor is installed, calculate the actual current by
		 * dividing the reported current by the sense resistor value
		 * in mOhm.
		 */
		val = DIV_ROUND_CLOSEST(val * 125, 2);
		break;
	default:
		return -EINVAL;
	}
	return val;
}

static ssize_t ltc4222_value_show(struct device *dev,
				  struct device_attribute *da, char *buf)
{

Annotation

Implementation Notes