rust: regulator: add a bare minimum regulator abstraction

Add a bare minimum regulator abstraction to be used by Rust drivers.
This abstraction adds a small subset of the regulator API, which is
thought to be sufficient for the drivers we have now.

Regulators provide the power needed by many hardware blocks and thus are
likely to be needed by a lot of drivers.

It was tested on rk3588, where it was used to power up the "mali"
regulator in order to power up the GPU.

Reviewed-by: Alexandre Courbot <[email protected]>
Signed-off-by: Daniel Almeida <[email protected]>
Reviewed-by: Alice Ryhl <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Mark Brown <[email protected]>

Author: dwlsalmeida

rust/bindings/bindings_helper.h

@@ -65,6 +65,7 @@
 #include <linux/poll.h>
 #include <linux/property.h>
 #include <linux/refcount.h>
+#include <linux/regulator/consumer.h>
 #include <linux/sched.h>
 #include <linux/security.h>
 #include <linux/slab.h>

rust/helpers/helpers.c

@@ -33,6 +33,7 @@
 #include "pci.c"
 #include "pid_namespace.c"
 #include "rbtree.c"
+#include "regulator.c"
 #include "rcu.c"
 #include "refcount.c"
 #include "security.c"

rust/helpers/regulator.c

@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/regulator/consumer.h>
+
+#ifndef CONFIG_REGULATOR
+
+void rust_helper_regulator_put(struct regulator *regulator)
+{
+	regulator_put(regulator);
+}
+
+int rust_helper_regulator_set_voltage(struct regulator *regulator, int min_uV,
+				      int max_uV)
+{
+	return regulator_set_voltage(regulator, min_uV, max_uV);
+}
+
+int rust_helper_regulator_get_voltage(struct regulator *regulator)
+{
+	return regulator_get_voltage(regulator);
+}
+
+struct regulator *rust_helper_regulator_get(struct device *dev, const char *id)
+{
+	return regulator_get(dev, id);
+}
+
+int rust_helper_regulator_enable(struct regulator *regulator)
+{
+	return regulator_enable(regulator);
+}
+
+int rust_helper_regulator_disable(struct regulator *regulator)
+{
+	return regulator_disable(regulator);
+}
+
+int rust_helper_regulator_is_enabled(struct regulator *regulator)
+{
+	return regulator_is_enabled(regulator);
+}
+
+#endif

rust/kernel/lib.rs

@@ -100,6 +100,7 @@ pub mod platform;
 pub mod prelude;
 pub mod print;
 pub mod rbtree;
+pub mod regulator;
 pub mod revocable;
 pub mod security;
 pub mod seq_file;