hwmon: Add LTC4245 driver

Add Linux support for the Linear Technology LTC4245 Multiple Supply Hot Swap controller I2C monitoring interface.

Signed-off-by Ira W. Snyder <[email protected]>

---

I've incorporated the suggestions from my first posting of this driver.

I decided to add current and power readings for the Vee (-12v) voltage, as well as the 12v, 5v, and 3v mentioned in the suggestions. This seemed reasonable to me.

I'd appreciate any more suggestions you may have. :)

drivers/hwmon/ltc4245.c new file +8 -0

+/* Return the voltage from the given register in millivolts */
+static u32 ltc4245_get_voltage(struct device *dev, u8 reg)
+{
+	struct ltc4245_data *data = ltc4245_update_device(dev);
+	const s32 val = data->vregs[reg - 0x10];
+	const u8 regval = val;
+	u32 mv = 0;
+

drivers/hwmon/ltc4245.c new file +11 -0

+	case LTC4245_GPIOADC1:
+	case LTC4245_GPIOADC2:
+	case LTC4245_GPIOADC3:
+		mv = regval * 10;
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		break;
+	}
+
+	return mv;

drivers/hwmon/ltc4245.c new file +17 -0

+static ssize_t ltc4245_show_voltage_alarm(struct device *dev,
+					  struct device_attribute *da,
+					  char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	struct ltc4245_data *data = ltc4245_update_device(dev);
+	const s32 fault1 = data->cregs[LTC4245_FAULT1];
+	int alarm = 0;
+
+	if (unlikely(fault1 < 0)) {
+		memset(buf, 0, PAGE_SIZE); /* user should not see old data */
+		return 0;
+	}
+
+	switch (attr->index) {
+	case LTC4245_12VIN:
+		alarm = fault1 & (1 << 0);

drivers/hwmon/ltc4245.c new file +32 -0

+	default:
+		/* If we get here, the developer messed up */
+		WARN_ON_ONCE(1);
+		break;
+	}
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", alarm ? 1 : 0);
+}
+
+static ssize_t ltc4245_show_current_alarm(struct device *dev,
+					  struct device_attribute *da,
+					  char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	struct ltc4245_data *data = ltc4245_update_device(dev);
+	const s32 fault1 = data->cregs[LTC4245_FAULT1];
+	int alarm = 0;
+
+	if (unlikely(fault1 < 0)) {
+		memset(buf, 0, PAGE_SIZE); /* user should not see old data */
+		return 0;
+	}
+
+	switch (attr->index) {
+	case LTC4245_12VSENSE:
+		alarm = fault1 & (1 << 4);
+		break;
+	case LTC4245_5VSENSE:
+		alarm = fault1 & (1 << 5);
+		break;
+	case LTC4245_3VSENSE:
+		alarm = fault1 & (1 << 6);

drivers/hwmon/ltc4245.c new file +20 -0

+	return snprintf(buf, PAGE_SIZE, "%d\n", alarm ? 1 : 0);
+}
+
+static ssize_t ltc4245_show_power_alarm(struct device *dev,
+					struct device_attribute *da,
+					char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	struct ltc4245_data *data = ltc4245_update_device(dev);
+	const s32 fault2 = data->cregs[LTC4245_FAULT2];
+	int alarm = 0;
+
+	if (unlikely(fault2 < 0)) {
+		memset(buf, 0, PAGE_SIZE); /* user should not see old data */
+		return 0;
+	}
+
+	switch (attr->index) {
+	case LTC4245_12VOUT:
+		alarm = fault2 & (1 << 0);

drivers/hwmon/ltc4245.c new file +7 -0

+	default:
+		/* If we get here, the developer messed up */
+		WARN_ON_ONCE(1);
+		break;
+	}
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", alarm ? 1 : 0);

drivers/hwmon/ltc4245.c new file +6 -0

+#define LTC4245_POWER_RO(name, ltc4245_cmd_idx) \
+	static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
+	ltc4245_show_power, NULL, ltc4245_cmd_idx)
+
 
+#define LTC4245_VOLTAGE_ALARM(name, ltc4245_cmd_idx) \
+	static SENSOR_DEVICE_ATTR(name, S_IRUGO, \

Documentation/hwmon/ltc4245 line 63

Quoted 4 lines · Ira Snyder

Documentation/hwmon/ltc4245 new file +4 -0

+power1_input		12v power usage (mW)
+power2_input		5v  power usage (mW)
+power3_input		3v  power usage (mW)
+power4_input		Vee (-12v) power usage (mW)

These should be in micro Watt so μW not mW, I know this is not consistentent with all other input's being in milli something, but the first piece of supported power measuring hardware we had has sub milliWatt precision, hence this decision.