[U-Boot] [PATCH] armv8: fsl-layerscape: Add support of disabling core prefetch

[Prabhakar Kushwaha]

Instruction prefetch feature is by default enabled during core
release.

This patch add support of disabling instruction prefetch by setting
core mask in PPA. Here each core mask bit represents a core and
prefetch is disabled at the time of core release.

Signed-off-by: Prabhakar Kushwaha <prabhakar.kushwaha at nxp.com>
---
 arch/arm/cpu/armv8/fsl-layerscape/cpu.c            | 38 ++++++++++++++++++++++
 .../armv8/fsl-layerscape/doc/README.core_prefetch  | 18 ++++++++++
 2 files changed, 56 insertions(+)
 create mode 100644 arch/arm/cpu/armv8/fsl-layerscape/doc/README.core_prefetch

diff --git a/arch/arm/cpu/armv8/fsl-layerscape/cpu.c b/arch/arm/cpu/armv8/fsl-layerscape/cpu.c
index ab5d76e..d082629 100644
--- a/arch/arm/cpu/armv8/fsl-layerscape/cpu.c
+++ b/arch/arm/cpu/armv8/fsl-layerscape/cpu.c
@@ -29,6 +29,7 @@
 #include <fsl_ddr.h>
 #endif
 #include <asm/arch/clock.h>
+#include <hwconfig.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -494,6 +495,41 @@ static inline int check_psci(void)
 	return 0;
 }
 
+static void config_core_prefetch(void)
+{
+	char *buf = NULL;
+	char buffer[HWCONFIG_BUFFER_SIZE];
+	const char *prefetch_arg = NULL;
+	size_t arglen;
+	unsigned int mask;
+	struct pt_regs regs;
+
+	if (env_get_f("hwconfig", buffer, sizeof(buffer)) > 0)
+		buf = buffer;
+
+	prefetch_arg = hwconfig_subarg_f("core_prefetch", "disable",
+					 &arglen, buf);
+
+	if (prefetch_arg) {
+		mask = simple_strtoul(prefetch_arg, NULL, 0) & 0xff;
+		if (mask & 0x1) {
+			printf("Core0 prefetch can't be disabled\n");
+			return;
+		}
+
+#define SIP_PREFETCH_DISABLE_64 0xC200FF13
+		regs.regs[0] = SIP_PREFETCH_DISABLE_64;
+		regs.regs[1] = mask;
+		smc_call(&regs);
+
+		if (regs.regs[0])
+			printf("Prefetch disable config failed for mask ");
+		else
+			printf("Prefetch disable config passed for mask ");
+		printf("0x%x\n", mask);
+	}
+}
+
 int arch_early_init_r(void)
 {
 #ifdef CONFIG_SYS_FSL_ERRATUM_A009635
@@ -521,6 +557,8 @@ int arch_early_init_r(void)
 	fsl_rgmii_init();
 #endif
 
+	config_core_prefetch();
+
 #ifdef CONFIG_SYS_HAS_SERDES
 	fsl_serdes_init();
 #endif
diff --git a/arch/arm/cpu/armv8/fsl-layerscape/doc/README.core_prefetch b/arch/arm/cpu/armv8/fsl-layerscape/doc/README.core_prefetch
new file mode 100644
index 0000000..f605a4c
--- /dev/null
+++ b/arch/arm/cpu/armv8/fsl-layerscape/doc/README.core_prefetch
@@ -0,0 +1,18 @@
+Core instruction prefetch disable
+---------------------------------
+To disable instruction prefetch of core; hwconfig needs to be updated.
+for e.g.
+setenv hwconfig 'fsl_ddr:bank_intlv=auto;core_prefetch:disable=0x02'
+
+Here 0x02 can be replaced with any valid value. It represents 64 bit mask.
+The 64-bit Mask has one bit for each core.
+Mask[0] = core0
+Mask[1] = core1
+Mask[2] = core2
+etc
+If the bit is set ('b1) in the mask, then prefetch is disabled for
+that core when it is released from reset.
+core0 prefetch should not be disabled.
+
+Once disabled, prefetch remains disabled until the next reset.
+There is no function to re-enable prefetch.
-- 
2.7.4