feat(st-regulator): add support for regulator-always-on

Add support for regulator-always-on at BL2 level as it was supported
before using the regulator framework.

Signed-off-by: Pascal Paillet <p.paillet@st.com>
Change-Id: Idb2f4ddc2fdd4e0d31fb33da87c84618aa2e5135

drivers/st/regulator/regulator_core.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, STMicroelectronics - All Rights Reserved
+ * Copyright (c) 2021-2022, STMicroelectronics - All Rights Reserved
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -156,6 +156,10 @@ int regulator_disable(struct rdev *rdev)
 
 	assert(rdev != NULL);
 
+	if (rdev->flags & REGUL_ALWAYS_ON) {
+		return 0;
+	}
+
 	ret = __regulator_set_state(rdev, STATE_DISABLE);
 
 	udelay(rdev->enable_ramp_delay);
@@ -412,6 +416,21 @@ int regulator_set_flag(struct rdev *rdev, uint16_t flag)
 	return 0;
 }
 
+static int parse_properties(const void *fdt, struct rdev *rdev, int node)
+{
+	int ret;
+
+	if (fdt_getprop(fdt, node, "regulator-always-on", NULL) != NULL) {
+		VERBOSE("%s: set regulator-always-on\n", rdev->desc->node_name);
+		ret = regulator_set_flag(rdev, REGUL_ALWAYS_ON);
+		if (ret != 0) {
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
 /*
  * Parse the device-tree for a regulator
  *
@@ -476,6 +495,11 @@ static int parse_dt(struct rdev *rdev, int node)
 		return ret;
 	}
 
+	ret = parse_properties(fdt, rdev, node);
+	if (ret != 0) {
+		return ret;
+	}
+
 	return 0;
 }