From a10d3632acbd1135648f07c2a998cba8c5c77cfd Mon Sep 17 00:00:00 2001 From: Jeenu Viswambharan Date: Fri, 6 Jan 2017 14:58:11 +0000 Subject: [PATCH] PSCI: Introduce cache and barrier wrappers The PSCI implementation performs cache maintenance operations on its data structures to ensure their visibility to both cache-coherent and non-cache-coherent participants. These cache maintenance operations can be skipped if all PSCI participants are cache-coherent. When HW_ASSISTED_COHERENCY build option is enabled, we assume PSCI participants are cache-coherent. For usage abstraction, this patch introduces wrappers for PSCI cache maintenance and barrier operations used for state coordination: they are effectively NOPs when HW_ASSISTED_COHERENCY is enabled, but are applied otherwise. Also refactor local state usage and associated cache operations to make it clearer. Change-Id: I77f17a90cba41085b7188c1345fe5731c99fad87 Signed-off-by: Jeenu Viswambharan --- lib/psci/psci_common.c | 79 ++++++++++++++++++++++++++--------------- lib/psci/psci_off.c | 12 +++---- lib/psci/psci_private.h | 23 ++++++++++++ lib/psci/psci_setup.c | 6 ++-- lib/psci/psci_suspend.c | 4 +-- 5 files changed, 85 insertions(+), 39 deletions(-) diff --git a/lib/psci/psci_common.c b/lib/psci/psci_common.c index 9fdce498..026690d2 100644 --- a/lib/psci/psci_common.c +++ b/lib/psci/psci_common.c @@ -247,6 +247,50 @@ static plat_local_state_t *psci_get_req_local_pwr_states(unsigned int pwrlvl, return &psci_req_local_pwr_states[pwrlvl - 1][cpu_idx]; } +/* + * psci_non_cpu_pd_nodes can be placed either in normal memory or coherent + * memory. + * + * With !USE_COHERENT_MEM, psci_non_cpu_pd_nodes is placed in normal memory, + * it's accessed by both cached and non-cached participants. To serve the common + * minimum, perform a cache flush before read and after write so that non-cached + * participants operate on latest data in main memory. + * + * When USE_COHERENT_MEM is used, psci_non_cpu_pd_nodes is placed in coherent + * memory. With HW_ASSISTED_COHERENCY, all PSCI participants are cache-coherent. + * In both cases, no cache operations are required. + */ + +/* + * Retrieve local state of non-CPU power domain node from a non-cached CPU, + * after any required cache maintenance operation. + */ +static plat_local_state_t get_non_cpu_pd_node_local_state( + unsigned int parent_idx) +{ +#if !USE_COHERENT_MEM || !HW_ASSISTED_COHERENCY + flush_dcache_range( + (uintptr_t) &psci_non_cpu_pd_nodes[parent_idx], + sizeof(psci_non_cpu_pd_nodes[parent_idx])); +#endif + return psci_non_cpu_pd_nodes[parent_idx].local_state; +} + +/* + * Update local state of non-CPU power domain node from a cached CPU; perform + * any required cache maintenance operation afterwards. + */ +static void set_non_cpu_pd_node_local_state(unsigned int parent_idx, + plat_local_state_t state) +{ + psci_non_cpu_pd_nodes[parent_idx].local_state = state; +#if !USE_COHERENT_MEM || !HW_ASSISTED_COHERENCY + flush_dcache_range( + (uintptr_t) &psci_non_cpu_pd_nodes[parent_idx], + sizeof(psci_non_cpu_pd_nodes[parent_idx])); +#endif +} + /****************************************************************************** * Helper function to return the current local power state of each power domain * from the current cpu power domain to its ancestor at the 'end_pwrlvl'. This @@ -264,18 +308,7 @@ void psci_get_target_local_pwr_states(unsigned int end_pwrlvl, /* Copy the local power state from node to state_info */ for (lvl = PSCI_CPU_PWR_LVL + 1; lvl <= end_pwrlvl; lvl++) { -#if !USE_COHERENT_MEM - /* - * If using normal memory for psci_non_cpu_pd_nodes, we need - * to flush before reading the local power state as another - * cpu in the same power domain could have updated it and this - * code runs before caches are enabled. - */ - flush_dcache_range( - (uintptr_t) &psci_non_cpu_pd_nodes[parent_idx], - sizeof(psci_non_cpu_pd_nodes[parent_idx])); -#endif - pd_state[lvl] = psci_non_cpu_pd_nodes[parent_idx].local_state; + pd_state[lvl] = get_non_cpu_pd_node_local_state(parent_idx); parent_idx = psci_non_cpu_pd_nodes[parent_idx].parent_node; } @@ -299,21 +332,16 @@ static void psci_set_target_local_pwr_states(unsigned int end_pwrlvl, psci_set_cpu_local_state(pd_state[PSCI_CPU_PWR_LVL]); /* - * Need to flush as local_state will be accessed with Data Cache + * Need to flush as local_state might be accessed with Data Cache * disabled during power on */ - flush_cpu_data(psci_svc_cpu_data.local_state); + psci_flush_cpu_data(psci_svc_cpu_data.local_state); parent_idx = psci_cpu_pd_nodes[plat_my_core_pos()].parent_node; /* Copy the local_state from state_info */ for (lvl = 1; lvl <= end_pwrlvl; lvl++) { - psci_non_cpu_pd_nodes[parent_idx].local_state = pd_state[lvl]; -#if !USE_COHERENT_MEM - flush_dcache_range( - (uintptr_t)&psci_non_cpu_pd_nodes[parent_idx], - sizeof(psci_non_cpu_pd_nodes[parent_idx])); -#endif + set_non_cpu_pd_node_local_state(parent_idx, pd_state[lvl]); parent_idx = psci_non_cpu_pd_nodes[parent_idx].parent_node; } } @@ -347,13 +375,8 @@ void psci_set_pwr_domains_to_run(unsigned int end_pwrlvl) /* Reset the local_state to RUN for the non cpu power domains. */ for (lvl = PSCI_CPU_PWR_LVL + 1; lvl <= end_pwrlvl; lvl++) { - psci_non_cpu_pd_nodes[parent_idx].local_state = - PSCI_LOCAL_STATE_RUN; -#if !USE_COHERENT_MEM - flush_dcache_range( - (uintptr_t) &psci_non_cpu_pd_nodes[parent_idx], - sizeof(psci_non_cpu_pd_nodes[parent_idx])); -#endif + set_non_cpu_pd_node_local_state(parent_idx, + PSCI_LOCAL_STATE_RUN); psci_set_req_local_pwr_state(lvl, cpu_idx, PSCI_LOCAL_STATE_RUN); @@ -364,7 +387,7 @@ void psci_set_pwr_domains_to_run(unsigned int end_pwrlvl) psci_set_aff_info_state(AFF_STATE_ON); psci_set_cpu_local_state(PSCI_LOCAL_STATE_RUN); - flush_cpu_data(psci_svc_cpu_data); + psci_flush_cpu_data(psci_svc_cpu_data); } /****************************************************************************** diff --git a/lib/psci/psci_off.c b/lib/psci/psci_off.c index 394aaa3b..94cf2ede 100644 --- a/lib/psci/psci_off.c +++ b/lib/psci/psci_off.c @@ -154,17 +154,17 @@ exit: */ if (rc == PSCI_E_SUCCESS) { /* - * Set the affinity info state to OFF. This writes directly to - * main memory as caches are disabled, so cache maintenance is + * Set the affinity info state to OFF. When caches are disabled, + * this writes directly to main memory, so cache maintenance is * required to ensure that later cached reads of aff_info_state - * return AFF_STATE_OFF. A dsbish() ensures ordering of the + * return AFF_STATE_OFF. A dsbish() ensures ordering of the * update to the affinity info state prior to cache line * invalidation. */ - flush_cpu_data(psci_svc_cpu_data.aff_info_state); + psci_flush_cpu_data(psci_svc_cpu_data.aff_info_state); psci_set_aff_info_state(AFF_STATE_OFF); - dsbish(); - inv_cpu_data(psci_svc_cpu_data.aff_info_state); + psci_dsbish(); + psci_inv_cpu_data(psci_svc_cpu_data.aff_info_state); #if ENABLE_RUNTIME_INSTRUMENTATION diff --git a/lib/psci/psci_private.h b/lib/psci/psci_private.h index ca8291e4..7f0204ad 100644 --- a/lib/psci/psci_private.h +++ b/lib/psci/psci_private.h @@ -38,6 +38,29 @@ #include #include +#if HW_ASSISTED_COHERENCY +/* + * On systems with hardware-assisted coherency, make PSCI cache operations NOP, + * as PSCI participants are cache-coherent, and there's no need for explicit + * cache maintenance operations or barriers to coordinate their state. + */ +#define psci_flush_dcache_range(addr, size) +#define psci_flush_cpu_data(member) +#define psci_inv_cpu_data(member) + +#define psci_dsbish() +#else +/* + * If not all PSCI participants are cache-coherent, perform cache maintenance + * and issue barriers wherever required to coordinate state. + */ +#define psci_flush_dcache_range(addr, size) flush_dcache_range(addr, size) +#define psci_flush_cpu_data(member) flush_cpu_data(member) +#define psci_inv_cpu_data(member) inv_cpu_data(member) + +#define psci_dsbish() dsbish() +#endif + /* * The following helper macros abstract the interface to the Bakery * Lock API. diff --git a/lib/psci/psci_setup.c b/lib/psci/psci_setup.c index 7327b92e..323dc62c 100644 --- a/lib/psci/psci_setup.c +++ b/lib/psci/psci_setup.c @@ -86,7 +86,7 @@ static void psci_init_pwr_domain_node(unsigned int node_idx, /* Set the power state to OFF state */ svc_cpu_data->local_state = PLAT_MAX_OFF_STATE; - flush_dcache_range((uintptr_t)svc_cpu_data, + psci_flush_dcache_range((uintptr_t)svc_cpu_data, sizeof(*svc_cpu_data)); cm_set_context_by_index(node_idx, @@ -242,9 +242,9 @@ int psci_setup(const psci_lib_args_t *lib_args) /* * Flush `psci_plat_pm_ops` as it will be accessed by secondary CPUs - * during warm boot before data cache is enabled. + * during warm boot, possibly before data cache is enabled. */ - flush_dcache_range((uintptr_t)&psci_plat_pm_ops, + psci_flush_dcache_range((uintptr_t)&psci_plat_pm_ops, sizeof(psci_plat_pm_ops)); /* Initialize the psci capability */ diff --git a/lib/psci/psci_suspend.c b/lib/psci/psci_suspend.c index 302116bd..23e5adab 100644 --- a/lib/psci/psci_suspend.c +++ b/lib/psci/psci_suspend.c @@ -91,10 +91,10 @@ static void psci_suspend_to_pwrdown_start(unsigned int end_pwrlvl, psci_set_suspend_pwrlvl(end_pwrlvl); /* - * Flush the target power level as it will be accessed on power up with + * Flush the target power level as it might be accessed on power up with * Data cache disabled. */ - flush_cpu_data(psci_svc_cpu_data.target_pwrlvl); + psci_flush_cpu_data(psci_svc_cpu_data.target_pwrlvl); /* * Call the cpu suspend handler registered by the Secure Payload -- 2.30.2