hwmon: (occ) Add sysfs entry for IPS (Idle Power Saver) status

BMC control applications need to check the Idle Power Saver status
byte returned by the OCC poll response, so export it in sysfs with
the other OCC-specific data.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20220215151022.7498-2-eajames@linux.ibm.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/occ/common.h

@@ -119,6 +119,7 @@ struct occ {
 	u8 prev_stat;
 	u8 prev_ext_stat;
 	u8 prev_occs_present;
+	u8 prev_ips_status;
 };
 
 int occ_setup(struct occ *occ, const char *name);

drivers/hwmon/occ/sysfs.c

@@ -63,6 +63,9 @@ static ssize_t occ_sysfs_show(struct device *dev,
 		else
 			val = 1;
 		break;
+	case 8:
+		val = header->ips_status;
+		break;
 	default:
 		return -EINVAL;
 	}
@@ -88,6 +91,7 @@ static SENSOR_DEVICE_ATTR(occ_mem_throttle, 0444, occ_sysfs_show, NULL, 4);
 static SENSOR_DEVICE_ATTR(occ_quick_pwr_drop, 0444, occ_sysfs_show, NULL, 5);
 static SENSOR_DEVICE_ATTR(occ_state, 0444, occ_sysfs_show, NULL, 6);
 static SENSOR_DEVICE_ATTR(occs_present, 0444, occ_sysfs_show, NULL, 7);
+static SENSOR_DEVICE_ATTR(occ_ips_status, 0444, occ_sysfs_show, NULL, 8);
 static DEVICE_ATTR_RO(occ_error);
 
 static struct attribute *occ_attributes[] = {
@@ -99,6 +103,7 @@ static struct attribute *occ_attributes[] = {
 	&sensor_dev_attr_occ_quick_pwr_drop.dev_attr.attr,
 	&sensor_dev_attr_occ_state.dev_attr.attr,
 	&sensor_dev_attr_occs_present.dev_attr.attr,
+	&sensor_dev_attr_occ_ips_status.dev_attr.attr,
 	&dev_attr_occ_error.attr,
 	NULL
 };
@@ -162,6 +167,11 @@ void occ_sysfs_poll_done(struct occ *occ)
 		sysfs_notify(&occ->bus_dev->kobj, NULL, name);
 	}
 
+	if (header->ips_status != occ->prev_ips_status) {
+		name = sensor_dev_attr_occ_ips_status.dev_attr.attr.name;
+		sysfs_notify(&occ->bus_dev->kobj, NULL, name);
+	}
+
 	if (occ->error && occ->error != occ->prev_error) {
 		name = dev_attr_occ_error.attr.name;
 		sysfs_notify(&occ->bus_dev->kobj, NULL, name);
@@ -174,6 +184,7 @@ done:
 	occ->prev_stat = header->status;
 	occ->prev_ext_stat = header->ext_status;
 	occ->prev_occs_present = header->occs_present;
+	occ->prev_ips_status = header->ips_status;
 }
 
 int occ_setup_sysfs(struct occ *occ)