feat(st-drivers): introduce fixed regulator driver

Fixed regulator is mainly used when no pmic is available

Change-Id: Ib6a998684bcb055ba95a093bee563372d9051474
Signed-off-by: Pascal Paillet <p.paillet@st.com>

drivers/st/regulator/regulator_fixed.c

@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2021, STMicroelectronics - All Rights Reserved
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <errno.h>
+
+#include <common/debug.h>
+#include <common/fdt_wrappers.h>
+#include <drivers/st/regulator.h>
+#include <drivers/st/regulator_fixed.h>
+#include <libfdt.h>
+
+#ifndef PLAT_NB_FIXED_REGS
+#error "Missing PLAT_NB_FIXED_REGS"
+#endif
+
+#define FIXED_NAME_LEN 32
+
+struct fixed_data {
+	char name[FIXED_NAME_LEN];
+	uint16_t volt;
+	struct regul_description desc;
+};
+
+static struct fixed_data data[PLAT_NB_FIXED_REGS];
+
+static int fixed_set_state(const struct regul_description *desc, bool state)
+{
+	return 0;
+}
+
+static int fixed_get_state(const struct regul_description *desc)
+{
+	return 1;
+}
+
+static struct regul_ops fixed_ops = {
+	.set_state = fixed_set_state,
+	.get_state = fixed_get_state,
+};
+
+int fixed_regulator_register(void)
+{
+	uint32_t count = 0;
+	void *fdt;
+	int node;
+
+	VERBOSE("fixed reg init!\n");
+
+	if (fdt_get_address(&fdt) == 0) {
+		return -FDT_ERR_NOTFOUND;
+	}
+
+	fdt_for_each_compatible_node(fdt, node, "regulator-fixed") {
+		int len __unused;
+		int ret;
+		struct fixed_data *d = &data[count];
+		const char *reg_name;
+
+		reg_name = fdt_get_name(fdt, node, NULL);
+
+		VERBOSE("register fixed reg %s!\n", reg_name);
+
+		len = snprintf(d->name, FIXED_NAME_LEN - 1, "%s", reg_name);
+		assert((len > 0) && (len < (FIXED_NAME_LEN - 1)));
+
+		d->desc.node_name = d->name;
+		d->desc.driver_data = d;
+		d->desc.ops = &fixed_ops;
+
+		ret = regulator_register(&d->desc, node);
+		if (ret != 0) {
+			WARN("%s:%d failed to register %s\n", __func__,
+			     __LINE__, reg_name);
+			return ret;
+		}
+
+		count++;
+		assert(count <= PLAT_NB_FIXED_REGS);
+
+	}
+
+	return 0;
+}

include/drivers/st/regulator_fixed.h

@@ -0,0 +1,12 @@
+/*
+ * Copyright (c) 2021, STMicroelectronics - All Rights Reserved
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef REGULATOR_FIXED_H
+#define REGULATOR_FIXED_H
+
+int fixed_regulator_register(void);
+
+#endif /* REGULATOR_FIXED_H */