[PATCH v7 5/8] arm64: add PSCI CPU_SUSPEND based cpu_suspend support

Lorenzo Pieralisi
2014-08-13T15:52:04Z

This patch implements the cpu_suspend cpu operations method through
the PSCI CPU SUSPEND API. The PSCI implementation translates the idle state
index passed by the cpu_suspend core call into a valid PSCI state according to
the PSCI states initialized at boot through the cpu_init_idle() CPU
operations hook.

The PSCI CPU suspend operation hook checks if the PSCI state is a
standby state. If it is, it calls the PSCI suspend implementation
straight away, without saving any context. If the state is a power
down state the kernel calls the __cpu_suspend API (that saves the CPU
context) and passed the PSCI suspend finisher as a parameter so that PSCI
can be called by the __cpu_suspend implementation after saving and flushing
the context as last function before power down.

For power down states, entry point is set to cpu_resume physical address,
that represents the default kernel execution address following a CPU reset.

Reviewed-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
arch/arm64/kernel/psci.c | 100 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 100 insertions(+)

diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
index 5539547..8258a77 100644
--- a/arch/arm64/kernel/psci.c
+++ b/arch/arm64/kernel/psci.c
@@ -21,6 +21,7 @@
#include <linux/reboot.h>
#include <linux/pm.h>
#include <linux/delay.h>
+#include <linux/slab.h>
#include <uapi/linux/psci.h>

#include <asm/compiler.h>
@@ -28,6 +29,7 @@
#include <asm/errno.h>
#include <asm/psci.h>
#include <asm/smp_plat.h>
+#include <asm/suspend.h>
#include <asm/system_misc.h>

#define PSCI_POWER_STATE_TYPE_STANDBY 0
@@ -65,6 +67,8 @@ enum psci_function {
PSCI_FN_MAX,
};

+static DEFINE_PER_CPU_READ_MOSTLY(struct psci_power_state *, psci_power_state);
+
static u32 psci_function_id[PSCI_FN_MAX];

static int psci_to_linux_errno(int errno)
@@ -93,6 +97,18 @@ static u32 psci_power_state_pack(struct psci_power_state state)
& PSCI_0_2_POWER_STATE_AFFL_MASK);
}

+static void psci_power_state_unpack(u32 power_state,
+ struct psci_power_state *state)
+{
+ state->id = (power_state & PSCI_0_2_POWER_STATE_ID_MASK) >>
+ PSCI_0_2_POWER_STATE_ID_SHIFT;
+ state->type = (power_state & PSCI_0_2_POWER_STATE_TYPE_MASK) >>
+ PSCI_0_2_POWER_STATE_TYPE_SHIFT;
+ state->affinity_level =
+ (power_state & PSCI_0_2_POWER_STATE_AFFL_MASK) >>
+ PSCI_0_2_POWER_STATE_AFFL_SHIFT;
+}
+
/*
* The following two functions are invoked via the invoke_psci_fn pointer
* and will not be inlined, allowing us to piggyback on the AAPCS.
@@ -199,6 +215,59 @@ static int psci_migrate_info_type(void)
return err;
}

+static int __maybe_unused cpu_psci_cpu_init_idle(struct device_node *cpu_node,
+ unsigned int cpu)
+{
+ int i, ret, count = 0;
+ struct psci_power_state *psci_states;
+ struct device_node *state_node;
+
+ /*
+ * If the PSCI cpu_suspend function hook has not been initialized
+ * idle states must not be enabled, so bail out
+ */
+ if (!psci_ops.cpu_suspend)
+ return -EOPNOTSUPP;
+
+ /* Count idle states */
+ while ((state_node = of_parse_phandle(cpu_node, "cpu-idle-states",
+ count)))
+ count++;
+
+ if (!count)
+ return -ENODEV;
+
+ psci_states = kcalloc(count, sizeof(*psci_states), GFP_KERNEL);
+ if (!psci_states)
+ return -ENOMEM;
+
+ for (i = 0; i < count; i++) {
+ u32 psci_power_state;
+
+ state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i);
+
+ ret = of_property_read_u32(state_node,
+ "arm,psci-suspend-param",
+ &psci_power_state);
+ if (ret) {
+ pr_warn(" * %s missing arm,psci-suspend-param property\n",
+ state_node->full_name);
+ goto free_mem;
+ }
+
+ pr_debug("psci-power-state %#x index %d\n", psci_power_state,
+ i);
+ psci_power_state_unpack(psci_power_state, &psci_states[i]);
+ }
+ /* Idle states parsed correctly, initialize per-cpu pointer */
+ per_cpu(psci_power_state, cpu) = psci_states;
+ return 0;
+
+free_mem:
+ kfree(psci_states);
+ return ret;
+}
+
static int get_set_conduit_method(struct device_node *np)
{
const char *method;
@@ -436,8 +505,39 @@ static int cpu_psci_cpu_kill(unsigned int cpu)
#endif
#endif

+static int psci_suspend_finisher(unsigned long index)
+{
+ struct psci_power_state *state = __get_cpu_var(psci_power_state);
+
+ return psci_ops.cpu_suspend(state[index - 1],
+ virt_to_phys(cpu_resume));
+}
+
+static int __maybe_unused cpu_psci_cpu_suspend(unsigned long index)
+{
+ int ret;
+ struct psci_power_state *state = __get_cpu_var(psci_power_state);
+ /*
+ * idle state index 0 corresponds to wfi, should never be called
+ * from the cpu_suspend operations
+ */
+ if (WARN_ON_ONCE(!index))
+ return -EINVAL;
+
+ if (state->type == PSCI_POWER_STATE_TYPE_STANDBY)
+ ret = psci_ops.cpu_suspend(state[index - 1], 0);
+ else
+ ret = __cpu_suspend(index, psci_suspend_finisher);
+
+ return ret;
+}
+
const struct cpu_operations cpu_psci_ops = {
.name = "psci",
+#ifdef CONFIG_CPU_IDLE
+ .cpu_init_idle = cpu_psci_cpu_init_idle,
+ .cpu_suspend = cpu_psci_cpu_suspend,
+#endif
#ifdef CONFIG_SMP
.cpu_init = cpu_psci_cpu_init,
.cpu_prepare = cpu_psci_cpu_prepare,
--
1.9.1