[RFC] coccinelle: Add test for unnecessary check before calling clk_disable_unprepare()

[Phil Edworthy <phil.edworthy@renesas.com>]

The clk_disable_unprepare() function only calls clk_disable() and
clk_unprepare(). Both of these functions already check the clk ptr
passed in using the IS_ERR_OR_NULL macro. Many drivers already omit
any checks on the clk ptr, so it is safe to assume this is true for
all call sites.

Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
---
Note that this is the first time I've used coccinelle so there may
be some clangers in the script below.
---
 .../api/clk_disable_unprepare.cocci           | 48 +++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 scripts/coccinelle/api/clk_disable_unprepare.cocci

diff --git a/scripts/coccinelle/api/clk_disable_unprepare.cocci b/scripts/coccinelle/api/clk_disable_unprepare.cocci
new file mode 100644
index 000000000000..17f00d3653c9
--- /dev/null
+++ b/scripts/coccinelle/api/clk_disable_unprepare.cocci
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/// Unnecessary check for valid ptr before calling clk_disable_unprepare
+///
+// Confidence: Moderate
+// Copyright: (C) 2022 Phil Edworthy
+// URL: http://coccinelle.lip6.fr/
+// Comments:
+// Options: --no-includes --include-headers
+
+virtual patch
+virtual context
+virtual org
+virtual report
+
+@depends on patch@
+expression clk;
+@@
+
+- if ( \( !clk \| clk != NULL \| !IS_ERR(clk)  \| !IS_ERR_OR_NULL(clk) \) )
+{
+clk_disable_unprepare(clk);
+}
+
+@r depends on !patch exists@
+expression clk;
+position p1,p2;
+@@
+
+if@p1 ( \( !clk \| clk != NULL \| !IS_ERR(clk)  \| !IS_ERR_OR_NULL(clk) \) )
+{
+clk_disable_unprepare@p2(clk);
+}
+
+@script:python depends on org@
+p1 << r.p1;
+p2 << r.p2;
+@@
+
+cocci.print_main("clk_disable_unprepare call",p1)
+cocci.print_secs("Unnecessary check tests",p2)
+
+@script:python depends on report@
+p1 << r.p1;
+p2 << r.p2;
+@@
+
+msg = "ERROR: clk_disable_unprepare already checks for valid ptr so check on line %s is not needed" % (p1[0].line)
+coccilib.report.print_report(p2[0], msg)
-- 
2.34.1