From 1e435256d625c203660f0105f1155cd2af283051 Mon Sep 17 00:00:00 2001
From: Olof Johansson <olof@lixom.net>
Date: Sat, 27 Apr 2013 14:10:18 -0700
Subject: [PATCH] clk: add clk_ignore_unused option to keep boot clocks on
This is primarily useful when there's a driver that doesn't claim clocks
properly, but the bootloader leaves them on. It's not expected to be used
in normal cases, but for bringup and debug it's very useful to have the
option to not gate unclaimed clocks that are still on.
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
[mturquette@linaro.org: fixed up trivial merge issue]
---
Documentation/clk.txt | 11 +++++++++++
Documentation/kernel-parameters.txt | 8 ++++++++
drivers/clk/clk.c | 13 +++++++++++++
3 files changed, 32 insertions(+)
diff --git a/Documentation/clk.txt b/Documentation/clk.txt
index 4274a546eb578..b9911c27f496e 100644
--- a/Documentation/clk.txt
+++ b/Documentation/clk.txt
@@ -231,3 +231,14 @@ To better enforce this policy, always follow this simple rule: any
statically initialized clock data MUST be defined in a separate file
from the logic that implements its ops. Basically separate the logic
from the data and all is well.
+
+ Part 6 - Disabling clock gating of unused clocks
+
+Sometimes during development it can be useful to be able to bypass the
+default disabling of unused clocks. For example, if drivers aren't enabling
+clocks properly but rely on them being on from the bootloader, bypassing
+the disabling means that the driver will remain functional while the issues
+are sorted out.
+
+To bypass this disabling, include "clk_ignore_unused" in the bootargs to the
+kernel.
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 4609e81dbc37f..9aa5562fed9cf 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -44,6 +44,7 @@ parameter is applicable:
AVR32 AVR32 architecture is enabled.
AX25 Appropriate AX.25 support is enabled.
BLACKFIN Blackfin architecture is enabled.
+ CLK Common clock infrastructure is enabled.
DRM Direct Rendering Management support is enabled.
DYNAMIC_DEBUG Build in debug messages and enable them at runtime
EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
@@ -465,6 +466,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
cio_ignore= [S390]
See Documentation/s390/CommonIO for details.
+ clk_ignore_unused
+ [CLK]
+ Keep all clocks already enabled by bootloader on,
+ even if no driver has claimed them. This is useful
+ for debug and development, but should not be
+ needed on a platform with proper driver support.
+ For more information, see Documentation/clk.txt.
clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
[Deprecated]
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 20ce67f82d65d..934cfd18f72de 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -499,10 +499,23 @@ static void clk_disable_unused_subtree(struct clk *clk)
return;
}
+static bool clk_ignore_unused;
+static int __init clk_ignore_unused_setup(char *__unused)
+{
+ clk_ignore_unused = true;
+ return 1;
+}
+__setup("clk_ignore_unused", clk_ignore_unused_setup);
+
static int clk_disable_unused(void)
{
struct clk *clk;
+ if (clk_ignore_unused) {
+ pr_warn("clk: Not disabling unused clocks\n");
+ return 0;
+ }
+
clk_prepare_lock();
hlist_for_each_entry(clk, &clk_root_list, child_node)