linux-kernel - [PATCH 1/3] ARM: cache-l2c: Add flag to skip cache unlocking

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Date:	Tue, 12 May 2015 00:17:29 +0200
From:	Sjoerd Simons <sjoerd.simons@...labora.co.uk>
To:	Rob Herring <robh@...nel.org>,
	Russell King <linux@....linux.org.uk>,
	Tony Lindgren <tony@...mide.com>
Cc:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
Subject: [PATCH 1/3] ARM: cache-l2c: Add flag to skip cache unlocking

The L2C cache should only be unlocked when the cache is setup to allow
that. In the common case the l2x0 driver sets up the cache for that to
be the case (e.g. setting L310_AUX_CTRL_NS_LOCKDOWN on L2C-310), making
unlock safe. However when a secure firmware is in use, it may not be
possible for the L2c to be configured that way making unlocking unsafe.

To handle that case add a flag to skip unlocking the cache for machine
where this can't be done safely.

Signed-off-by: Sjoerd Simons <sjoerd.simons@...labora.co.uk>
---
 arch/arm/include/asm/outercache.h | 1 +
 arch/arm/mm/cache-l2x0.c          | 4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/outercache.h b/arch/arm/include/asm/outercache.h
index 563b92f..d07ca82 100644
--- a/arch/arm/include/asm/outercache.h
+++ b/arch/arm/include/asm/outercache.h
@@ -39,6 +39,7 @@ struct outer_cache_fns {
 	/* This is an ARM L2C thing */
 	void (*write_sec)(unsigned long, unsigned);
 	void (*configure)(const struct l2x0_regs *);
+	bool skip_unlock;
 };
 
 extern struct outer_cache_fns outer_cache;
diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
index e309c8f..fff7888 100644
--- a/arch/arm/mm/cache-l2x0.c
+++ b/arch/arm/mm/cache-l2x0.c
@@ -136,7 +136,8 @@ static void l2c_enable(void __iomem *base, u32 aux, unsigned num_lock)
 	l2x0_saved_regs.aux_ctrl = aux;
 	l2c_configure(base);
 
-	l2c_unlock(base, num_lock);
+	if (!outer_cache.skip_unlock)
+		l2c_unlock(base, num_lock);
 
 	local_irq_save(flags);
 	__l2c_op_way(base + L2X0_INV_WAY);
@@ -849,6 +850,7 @@ static int __init __l2c_init(const struct l2c_init_data *data,
 	fns = data->outer_cache;
 	fns.write_sec = outer_cache.write_sec;
 	fns.configure = outer_cache.configure;
+	fns.skip_unlock = outer_cache.skip_unlock;
 	if (data->fixup)
 		data->fixup(l2x0_base, cache_id, &fns);
 
-- 
2.1.4

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