linux-kernel - [PATCH 7/7] ARM: tegra: clock: Disable clocks left on by bootloader

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Date:	Mon, 21 Feb 2011 18:39:52 -0800
From:	Colin Cross <ccross@...roid.com>
To:	linux-tegra@...r.kernel.org
Cc:	konkers@...roid.com, olof@...om.net,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	mike@...pulab.co.il, Colin Cross <ccross@...roid.com>,
	Russell King <linux@....linux.org.uk>
Subject: [PATCH 7/7] ARM: tegra: clock: Disable clocks left on by bootloader

Iterates through all clocks, disabling any for which the
refcount is 0 but the clock init detected the bootloader
left the clock on.  Can be disabled with command line
tegra_clock.disable_boot_clocks=N

Signed-off-by: Colin Cross <ccross@...roid.com>
---
 arch/arm/mach-tegra/clock.c |   44 +++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 44 insertions(+), 0 deletions(-)

diff --git a/arch/arm/mach-tegra/clock.c b/arch/arm/mach-tegra/clock.c
index e028320..6d686ff 100644
--- a/arch/arm/mach-tegra/clock.c
+++ b/arch/arm/mach-tegra/clock.c
@@ -33,6 +33,9 @@
 #include "board.h"
 #include "clock.h"
 
+#undef MODULE_PARAM_PREFIX
+#define MODULE_PARAM_PREFIX "tegra_clock."
+
 /*
  * Locking:
  *
@@ -416,6 +419,47 @@ void tegra_sdmmc_tap_delay(struct clk *c, int delay)
 	spin_unlock_irqrestore(&c->spinlock, flags);
 }
 
+static bool tegra_disable_boot_clocks = true;
+module_param_named(disable_boot_clocks, tegra_disable_boot_clocks, bool,
+	S_IRUGO | S_IWUSR | S_IWGRP);
+
+/*
+ * Iterate through all clocks, disabling any for which the refcount is 0
+ * but the clock init detected the bootloader left the clock on.
+ */
+static int __init tegra_init_disable_boot_clocks(void)
+{
+	struct clk *c;
+
+	mutex_lock(&clock_list_lock);
+
+	list_for_each_entry(c, &clocks, node) {
+		spin_lock_irq(&c->spinlock);
+
+		if (c->refcnt == 0 && c->state == ON &&
+				c->ops && c->ops->disable) {
+			pr_warn_once("%s clocks left on by bootloader:\n",
+				tegra_disable_boot_clocks ?
+					"Disabling" :
+					"Prevented disabling");
+
+			pr_warn("   %s\n", c->name);
+
+			if (tegra_disable_boot_clocks) {
+				c->ops->disable(c);
+				c->state = OFF;
+			}
+		}
+
+		spin_unlock_irq(&c->spinlock);
+	}
+
+	mutex_unlock(&clock_list_lock);
+
+	return 0;
+}
+late_initcall(tegra_init_disable_boot_clocks);
+
 #ifdef CONFIG_DEBUG_FS
 
 static int __clk_lock_all_spinlocks(void)
-- 
1.7.3.1

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