armv8: fsl-layerscape: Add support of disabling core prefetch

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@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>

diff --git a/arch/arm/cpu/armv8/fsl-layerscape/cpu.c b/arch/arm/cpu/armv8/fsl-layerscape/cpu.c
index ab5d76e..d082629 100644 (file)
--- 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 (file)
index 0000000..85cf6ab
--- /dev/null
+++ b/arch/arm/cpu/armv8/fsl-layerscape/doc/README.core_prefetch
@@ -0,0 +1,20 @@
+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 except Mask[0] bit. 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 i.e. Mask[0] should never be set.
+Setting Mask[0] may lead to undefined behavior.
+
+Once disabled, prefetch remains disabled until the next reset.
+There is no function to re-enable prefetch.