Re: [PATCH v4 5/7] ARM: EXYNOS: Add .write_sec outer cache callback for L2C-310

[Russell King - ARM Linux]

On Tue, Aug 26, 2014 at 04:17:58PM +0200, Tomasz Figa wrote:
 Exynos4 SoCs equipped with an L2C-310 cache controller and running under
 secure firmware require certain registers of aforementioned IP to be
 accessed only from secure mode. This means that SMC calls are required
 for certain register writes. To handle this, an implementation of
 .write_sec and .configure callbacks is provided by this patch.
 
 Signed-off-by: Tomasz Figa t.f...@samsung.com
 ---
  arch/arm/mach-exynos/firmware.c | 38 ++
  1 file changed, 38 insertions(+)
 
 diff --git a/arch/arm/mach-exynos/firmware.c b/arch/arm/mach-exynos/firmware.c
 index f5e626d..554b350 100644
 --- a/arch/arm/mach-exynos/firmware.c
 +++ b/arch/arm/mach-exynos/firmware.c
 @@ -17,6 +17,7 @@
  #include asm/cacheflush.h
  #include asm/cputype.h
  #include asm/firmware.h
 +#include asm/hardware/cache-l2x0.h
  #include asm/suspend.h
  
  #include mach/map.h
 @@ -120,6 +121,31 @@ static const struct firmware_ops exynos_firmware_ops = {
   .resume = exynos_resume,
  };
  
 +static void exynos_l2_write_sec(unsigned long val, unsigned reg)
 +{
 + switch (reg) {
 + case L2X0_CTRL:
 + if (val  L2X0_CTRL_EN)
 + exynos_smc(SMC_CMD_L2X0INVALL, 0, 0, 0);

If we're calling this with the cache already enabled, presumably you're
doing this to cover the case where we're disabling the cache.

1. Do you really want to *invalidate* the L2 cache, discarding its
   contents?
2. Don't you think that... if you needed something like this here, then
   it could be a defficiency in the common code?

If (2) doesn't apply, then should be a comment here why this is needed.

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[PATCH v4 5/7] ARM: EXYNOS: Add .write_sec outer cache callback for L2C-310

[Tomasz Figa]

Exynos4 SoCs equipped with an L2C-310 cache controller and running under
secure firmware require certain registers of aforementioned IP to be
accessed only from secure mode. This means that SMC calls are required
for certain register writes. To handle this, an implementation of
.write_sec and .configure callbacks is provided by this patch.

Signed-off-by: Tomasz Figa t.f...@samsung.com
---
 arch/arm/mach-exynos/firmware.c | 38 ++
 1 file changed, 38 insertions(+)

diff --git a/arch/arm/mach-exynos/firmware.c b/arch/arm/mach-exynos/firmware.c
index f5e626d..554b350 100644
--- a/arch/arm/mach-exynos/firmware.c
+++ b/arch/arm/mach-exynos/firmware.c
@@ -17,6 +17,7 @@
 #include asm/cacheflush.h
 #include asm/cputype.h
 #include asm/firmware.h
+#include asm/hardware/cache-l2x0.h
 #include asm/suspend.h
 
 #include mach/map.h
@@ -120,6 +121,31 @@ static const struct firmware_ops exynos_firmware_ops = {
.resume = exynos_resume,
 };
 
+static void exynos_l2_write_sec(unsigned long val, unsigned reg)
+{
+   switch (reg) {
+   case L2X0_CTRL:
+   if (val  L2X0_CTRL_EN)
+   exynos_smc(SMC_CMD_L2X0INVALL, 0, 0, 0);
+   exynos_smc(SMC_CMD_L2X0CTRL, val, 0, 0);
+   break;
+
+   case L2X0_DEBUG_CTRL:
+   exynos_smc(SMC_CMD_L2X0DEBUG, val, 0, 0);
+   break;
+
+   default:
+   WARN_ONCE(1, %s: ignoring write to reg 0x%x\n, __func__, reg);
+   }
+}
+
+static void exynos_l2_configure(const struct l2x0_regs *regs)
+{
+   exynos_smc(SMC_CMD_L2X0SETUP1, regs-tag_latency, regs-data_latency,
+   regs-prefetch_ctrl);
+   exynos_smc(SMC_CMD_L2X0SETUP2, regs-pwr_ctrl, regs-aux_ctrl, 0);
+}
+
 void __init exynos_firmware_init(void)
 {
struct device_node *nd;
@@ -139,4 +165,16 @@ void __init exynos_firmware_init(void)
pr_info(Running under secure firmware.\n);
 
register_firmware_ops(exynos_firmware_ops);
+
+   /*
+* Exynos 4 SoCs (based on Cortex A9 and equipped with L2C-310),
+* running under secure firmware, require certain registers of L2
+* cache controller to be written in secure mode. Here .write_sec
+* callback is provided to perform necessary SMC calls.
+*/
+   if (IS_ENABLED(CONFIG_CACHE_L2X0)
+read_cpuid_part() == ARM_CPU_PART_CORTEX_A9) {
+   outer_cache.write_sec = exynos_l2_write_sec;
+   outer_cache.configure = exynos_l2_configure;
+   }
 }
-- 
2.0.4

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