[PATCH v4 01/21] drivers: reset: Add devm_to_reset() to return dummy "struct reset_ctl"

[Kishon Vijay Abraham I]

Add devm_to_reset() to return dummy "struct reset_ctl", useful for
invoking reset APIs which doesn't have a valid "struct reset_ctl".

Suggested-by: Simon Glass <s...@chromium.org>
Signed-off-by: Kishon Vijay Abraham I <kis...@ti.com>
---
 drivers/reset/reset-uclass.c       | 16 ++++++++++++++++
 drivers/reset/sandbox-reset-test.c |  4 +++-
 include/reset.h                    | 17 +++++++++++++++++
 3 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/drivers/reset/reset-uclass.c b/drivers/reset/reset-uclass.c
index 8caa616ed9..9f2eeb4fe4 100644
--- a/drivers/reset/reset-uclass.c
+++ b/drivers/reset/reset-uclass.c
@@ -15,6 +15,8 @@
 #include <dm/devres.h>
 #include <dm/lists.h>
 
+static struct reset_ctl devm_no_reset;
+
 static inline struct reset_ops *reset_dev_ops(struct udevice *dev)
 {
        return (struct reset_ops *)dev->driver->ops;
@@ -256,6 +258,20 @@ int reset_release_all(struct reset_ctl *reset_ctl, int 
count)
        return 0;
 }
 
+int devm_to_reset(struct reset_ctl *in, struct reset_ctl **outp)
+{
+       if (IS_ERR_OR_NULL(in)) {
+               *outp = &devm_no_reset;
+               if (!in)
+                       return -ENOENT;
+               else
+                       return PTR_ERR(in);
+       }
+       *outp = in;
+
+       return 0;
+}
+
 static void devm_reset_release(struct udevice *dev, void *res)
 {
        reset_free(res);
diff --git a/drivers/reset/sandbox-reset-test.c 
b/drivers/reset/sandbox-reset-test.c
index 51b79810c8..4389bde5e7 100644
--- a/drivers/reset/sandbox-reset-test.c
+++ b/drivers/reset/sandbox-reset-test.c
@@ -32,13 +32,15 @@ int sandbox_reset_test_get_devm(struct udevice *dev)
 {
        struct sandbox_reset_test *sbrt = dev_get_priv(dev);
        struct reset_ctl *r;
+       int ret;
 
        r = devm_reset_control_get(dev, "not-a-valid-reset-ctl");
        if (!IS_ERR(r))
                return -EINVAL;
 
        r = devm_reset_control_get_optional(dev, "not-a-valid-reset-ctl");
-       if (r)
+       ret = devm_to_reset(r, &r);
+       if (reset_valid(r))
                return -EINVAL;
 
        sbrt->ctlp = devm_reset_control_get(dev, "test");
diff --git a/include/reset.h b/include/reset.h
index cde2c4b4a8..21affc1455 100644
--- a/include/reset.h
+++ b/include/reset.h
@@ -341,6 +341,18 @@ int reset_status(struct reset_ctl *reset_ctl);
  */
 int reset_release_all(struct reset_ctl *reset_ctl, int count);
 
+/**
+ * devm_to_reset - Provide a dummy reset_ctl for invalid reset_ctl
+ *
+ * Provide a dummy reset_ctl for invalid reset_ctl or give the same
+ * input reset_ctl
+ *
+ * @in:        Input reset_ctl returned by devm_reset_control_get()
+ * @outp: Dummy reset_ctl for invalid reset_ctl or Input reset_ctl
+ * @return 0 if OK, or a negative error code.
+ */
+int devm_to_reset(struct reset_ctl *in, struct reset_ctl **outp);
+
 /**
  * reset_release_bulk - Assert/Free an array of previously requested reset
  * signals in a reset control bulk struct.
@@ -456,6 +468,11 @@ static inline int reset_release_bulk(struct reset_ctl_bulk 
*bulk)
 {
        return 0;
 }
+
+static inline int devm_to_reset(struct reset_ctl *in, struct reset_ctl **outp)
+{
+       return 0;
+}
 #endif
 
 /**
-- 
2.17.1