ARM: trusted_foundations: Support L2 cache maintenance

Implement L2 cache initialization firmware callback that should be
invoked early during boot in order to set up the required outer cache
driver's callbacks and add the callback required for L2X0 maintenance.

Partially based on work done by Michał Mirosław [1].

[1] https://www.spinics.net/lists/arm-kernel/msg594765.htmlTested-by: Robert Yang <decatf@gmail.com>
Tested-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm/firmware/trusted_foundations.c

@@ -18,8 +18,15 @@
 #include <linux/init.h>
 #include <linux/of.h>
 #include <asm/firmware.h>
+#include <asm/hardware/cache-l2x0.h>
+#include <asm/outercache.h>
 #include <asm/trusted_foundations.h>
 
+#define TF_CACHE_MAINT		0xfffff100
+
+#define TF_CACHE_ENABLE		1
+#define TF_CACHE_DISABLE	2
+
 #define TF_SET_CPU_BOOT_ADDR_SMC 0xfffff200
 
 #define TF_CPU_PM		0xfffffffc
@@ -67,9 +74,43 @@ static int tf_prepare_idle(void)
 	return 0;
 }
 
+#ifdef CONFIG_CACHE_L2X0
+static void tf_cache_write_sec(unsigned long val, unsigned int reg)
+{
+	u32 l2x0_way_mask = 0xff;
+
+	switch (reg) {
+	case L2X0_CTRL:
+		if (l2x0_saved_regs.aux_ctrl & L310_AUX_CTRL_ASSOCIATIVITY_16)
+			l2x0_way_mask = 0xffff;
+
+		if (val == L2X0_CTRL_EN)
+			tf_generic_smc(TF_CACHE_MAINT, TF_CACHE_ENABLE,
+				       l2x0_saved_regs.aux_ctrl);
+		else
+			tf_generic_smc(TF_CACHE_MAINT, TF_CACHE_DISABLE,
+				       l2x0_way_mask);
+		break;
+
+	default:
+		break;
+	}
+}
+
+static int tf_init_cache(void)
+{
+	outer_cache.write_sec = tf_cache_write_sec;
+
+	return 0;
+}
+#endif /* CONFIG_CACHE_L2X0 */
+
 static const struct firmware_ops trusted_foundations_ops = {
 	.set_cpu_boot_addr = tf_set_cpu_boot_addr,
 	.prepare_idle = tf_prepare_idle,
+#ifdef CONFIG_CACHE_L2X0
+	.l2x0_init = tf_init_cache,
+#endif
 };
 
 void register_trusted_foundations(struct trusted_foundations_platform_data *pd)

arch/arm/include/asm/trusted_foundations.h

@@ -32,6 +32,9 @@
 #include <linux/cpu.h>
 #include <linux/smp.h>
 
+#include <asm/hardware/cache-l2x0.h>
+#include <asm/outercache.h>
+
 struct trusted_foundations_platform_data {
 	unsigned int version_major;
 	unsigned int version_minor;
@@ -43,6 +46,9 @@ void register_trusted_foundations(struct trusted_foundations_platform_data *pd);
 void of_register_trusted_foundations(void);
 
 #else /* CONFIG_TRUSTED_FOUNDATIONS */
+static inline void tf_dummy_write_sec(unsigned long val, unsigned int reg)
+{
+}
 
 static inline void register_trusted_foundations(
 				   struct trusted_foundations_platform_data *pd)
@@ -53,6 +59,10 @@ static inline void register_trusted_foundations(
 	 */
 	pr_err("No support for Trusted Foundations, continuing in degraded mode.\n");
 	pr_err("Secondary processors as well as CPU PM will be disabled.\n");
+#if IS_ENABLED(CONFIG_CACHE_L2X0)
+	pr_err("L2X0 cache will be kept disabled.\n");
+	outer_cache.write_sec = tf_dummy_write_sec;
+#endif
 #if IS_ENABLED(CONFIG_SMP)
 	setup_max_cpus = 0;
 #endif