ARM: mcpm: introduce the CPU/cluster power API
This is the basic API used to handle the powering up/down of individual
CPUs in a (multi-)cluster system. The platform specific backend
implementation has the responsibility to also handle the cluster level
power as well when the first/last CPU in a cluster is brought up/down.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
diff --git a/arch/arm/common/mcpm_entry.c b/arch/arm/common/mcpm_entry.c
index 7cbf7005..5d72889 100644
--- a/arch/arm/common/mcpm_entry.c
+++ b/arch/arm/common/mcpm_entry.c
@@ -9,8 +9,13 @@
* published by the Free Software Foundation.
*/
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/irqflags.h>
+
#include <asm/mcpm.h>
#include <asm/cacheflush.h>
+#include <asm/idmap.h>
extern unsigned long mcpm_entry_vectors[MAX_NR_CLUSTERS][MAX_CPUS_PER_CLUSTER];
@@ -20,3 +25,89 @@
mcpm_entry_vectors[cluster][cpu] = val;
sync_cache_w(&mcpm_entry_vectors[cluster][cpu]);
}
+
+static const struct mcpm_platform_ops *platform_ops;
+
+int __init mcpm_platform_register(const struct mcpm_platform_ops *ops)
+{
+ if (platform_ops)
+ return -EBUSY;
+ platform_ops = ops;
+ return 0;
+}
+
+int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster)
+{
+ if (!platform_ops)
+ return -EUNATCH; /* try not to shadow power_up errors */
+ might_sleep();
+ return platform_ops->power_up(cpu, cluster);
+}
+
+typedef void (*phys_reset_t)(unsigned long);
+
+void mcpm_cpu_power_down(void)
+{
+ phys_reset_t phys_reset;
+
+ BUG_ON(!platform_ops);
+ BUG_ON(!irqs_disabled());
+
+ /*
+ * Do this before calling into the power_down method,
+ * as it might not always be safe to do afterwards.
+ */
+ setup_mm_for_reboot();
+
+ platform_ops->power_down();
+
+ /*
+ * It is possible for a power_up request to happen concurrently
+ * with a power_down request for the same CPU. In this case the
+ * power_down method might not be able to actually enter a
+ * powered down state with the WFI instruction if the power_up
+ * method has removed the required reset condition. The
+ * power_down method is then allowed to return. We must perform
+ * a re-entry in the kernel as if the power_up method just had
+ * deasserted reset on the CPU.
+ *
+ * To simplify race issues, the platform specific implementation
+ * must accommodate for the possibility of unordered calls to
+ * power_down and power_up with a usage count. Therefore, if a
+ * call to power_up is issued for a CPU that is not down, then
+ * the next call to power_down must not attempt a full shutdown
+ * but only do the minimum (normally disabling L1 cache and CPU
+ * coherency) and return just as if a concurrent power_up request
+ * had happened as described above.
+ */
+
+ phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset);
+ phys_reset(virt_to_phys(mcpm_entry_point));
+
+ /* should never get here */
+ BUG();
+}
+
+void mcpm_cpu_suspend(u64 expected_residency)
+{
+ phys_reset_t phys_reset;
+
+ BUG_ON(!platform_ops);
+ BUG_ON(!irqs_disabled());
+
+ /* Very similar to mcpm_cpu_power_down() */
+ setup_mm_for_reboot();
+ platform_ops->suspend(expected_residency);
+ phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset);
+ phys_reset(virt_to_phys(mcpm_entry_point));
+ BUG();
+}
+
+int mcpm_cpu_powered_up(void)
+{
+ if (!platform_ops)
+ return -EUNATCH;
+ if (platform_ops->powered_up)
+ platform_ops->powered_up();
+ return 0;
+}