ARM: mcpm: add a simple poke mechanism to the early entry code

This allows to poke a predetermined value into a specific address
upon entering the early boot code in bL_head.S.

Signed-off-by: Nicolas Pitre <nico@linaro.org>

diff --git a/arch/arm/common/mcpm_entry.c b/arch/arm/common/mcpm_entry.c
index 370236dd1a03309ee3b123e705aa80132c908427..4a2b32fd53a19df6d87ae4b85795e56813e7b06a 100644 (file)
--- a/arch/arm/common/mcpm_entry.c
+++ b/arch/arm/common/mcpm_entry.c
@@ -27,6 +27,18 @@ void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr)
        sync_cache_w(&mcpm_entry_vectors[cluster][cpu]);
 }
 
+extern unsigned long mcpm_entry_early_pokes[MAX_NR_CLUSTERS][MAX_CPUS_PER_CLUSTER][2];
+
+void mcpm_set_early_poke(unsigned cpu, unsigned cluster,
+                        unsigned long poke_phys_addr, unsigned long poke_val)
+{
+       unsigned long *poke = &mcpm_entry_early_pokes[cluster][cpu][0];
+       poke[0] = poke_phys_addr;
+       poke[1] = poke_val;
+       __cpuc_flush_dcache_area((void *)poke, 8);
+       outer_clean_range(__pa(poke), __pa(poke + 2));
+}
+
 static const struct mcpm_platform_ops *platform_ops;
 
 int __init mcpm_platform_register(const struct mcpm_platform_ops *ops)

diff --git a/arch/arm/common/mcpm_head.S b/arch/arm/common/mcpm_head.S
index 39c96df3477a41549d71e1a18733dd85f4a168df..49dd5352fe70336ff023d3c40097a03d4370902f 100644 (file)
--- a/arch/arm/common/mcpm_head.S
+++ b/arch/arm/common/mcpm_head.S
@@ -71,12 +71,19 @@ ENTRY(mcpm_entry_point)
         * position independent way.
         */
        adr     r5, 3f
-       ldmia   r5, {r6, r7, r8, r11}
+       ldmia   r5, {r0, r6, r7, r8, r11}
+       add     r0, r5, r0                      @ r0 = mcpm_entry_early_pokes
        add     r6, r5, r6                      @ r6 = mcpm_entry_vectors
        ldr     r7, [r5, r7]                    @ r7 = mcpm_power_up_setup_phys
        add     r8, r5, r8                      @ r8 = mcpm_sync
        add     r11, r5, r11                    @ r11 = first_man_locks
 
+       @ Perform an early poke, if any
+       add     r0, r0, r4, lsl #3
+       ldmia   r0, {r0, r1}
+       teq     r0, #0
+       strne   r1, [r0]
+
        mov     r0, #MCPM_SYNC_CLUSTER_SIZE
        mla     r8, r0, r10, r8                 @ r8 = sync cluster base
 
@@ -195,7 +202,8 @@ mcpm_entry_gated:
 
        .align  2
 
-3:     .word   mcpm_entry_vectors - .
+3:     .word   mcpm_entry_early_pokes - .
+       .word   mcpm_entry_vectors - 3b
        .word   mcpm_power_up_setup_phys - 3b
        .word   mcpm_sync - 3b
        .word   first_man_locks - 3b
@@ -214,6 +222,10 @@ first_man_locks:
 ENTRY(mcpm_entry_vectors)
        .space  4 * MAX_NR_CLUSTERS * MAX_CPUS_PER_CLUSTER
 
+       .type   mcpm_entry_early_pokes, #object
+ENTRY(mcpm_entry_early_pokes)
+       .space  8 * MAX_NR_CLUSTERS * MAX_CPUS_PER_CLUSTER
+
        .type   mcpm_power_up_setup_phys, #object
 ENTRY(mcpm_power_up_setup_phys)
        .space  4               @ set by mcpm_sync_init()

diff --git a/arch/arm/include/asm/mcpm.h b/arch/arm/include/asm/mcpm.h
index 0f7b7620e9a554b0b4a0ba4939a60c905e0a435c..7626a7fd49385ee7d00cec3e7ae947d4eabdb016 100644 (file)
--- a/arch/arm/include/asm/mcpm.h
+++ b/arch/arm/include/asm/mcpm.h
@@ -41,6 +41,14 @@ extern void mcpm_entry_point(void);
  */
 void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr);
 
+/*
+ * This sets an early poke i.e a value to be poked into some address
+ * from very early assembly code before the CPU is ungated.  The
+ * address must be physical, and if 0 then nothing will happen.
+ */
+void mcpm_set_early_poke(unsigned cpu, unsigned cluster,
+                        unsigned long poke_phys_addr, unsigned long poke_val);
+
 /*
  * CPU/cluster power operations API for higher subsystems to use.
  */