On Mon, Jun 7, 2021 at 12:09 AM Samuel Holland [off-list ref] wrote:

On 6/2/21 6:23 AM, Anup Patel wrote:

quoted

The RISC-V SBI HSM extension provides HSM suspend call which can
be used by Linux RISC-V to enter platform specific low-power state.

This patch adds a CPU idle driver based on RISC-V SBI calls which
will populate idle states from device tree and use SBI calls to
entry these idle states.

Signed-off-by: Anup Patel <redacted>
---
 MAINTAINERS                   |   7 +
 drivers/cpuidle/Kconfig       |   5 +
 drivers/cpuidle/Kconfig.riscv |  15 +
 drivers/cpuidle/Makefile      |   4 +
 drivers/cpuidle/cpuidle-sbi.c | 626 ++++++++++++++++++++++++++++++++++
 5 files changed, 657 insertions(+)
 create mode 100644 drivers/cpuidle/Kconfig.riscv
 create mode 100644 drivers/cpuidle/cpuidle-sbi.c

...

diff --git a/drivers/cpuidle/cpuidle-sbi.c b/drivers/cpuidle/cpuidle-sbi.c
new file mode 100644
index 000000000000..f743684d07de
--- /dev/null
+++ b/drivers/cpuidle/cpuidle-sbi.c

@@ -0,0 +1,626 @@

...
+     /* Initialize idle states from DT. */
+     ret = sbi_cpuidle_dt_init_states(dev, drv, cpu, state_count);
+     if (ret) {
+             pr_err("HART%ld: failed to init idle states\n",
+                    cpuid_to_hartid_map(cpu));
+             return ret;
+     }
+
+     ret = cpuidle_register(drv, NULL);
+     if (ret)
+             goto deinit;
+
+     cpuidle_cooling_register(drv);
+
+     return 0;
+deinit:
+     sbi_cpuidle_deinit_cpu(cpu);
+     return ret;
+}
+
+static int sbi_cpuidle_pd_power_off(struct generic_pm_domain *pd)

This function should be moved inside the CONFIG_DT_IDLE_GENPD block
below. Otherwise it is defined but unused.

Indeed, sbi_cpuidle_pd_power_off() should be under
"#ifdef CONFIG_DT_IDLE_GENPD". I will update in the
next patch revision.

quoted

+{
+     struct genpd_power_state *state = &pd->states[pd->state_idx];
+     u32 *pd_state;
+
+     if (!state->data)
+             return 0;
+
+     if (!sbi_cpuidle_pd_allow_domain_state)
+             return -EBUSY;
+
+     /* OSI mode is enabled, set the corresponding domain state. */
+     pd_state = state->data;
+     sbi_set_domain_state(*pd_state);
+
+     return 0;
+}
+
+static void sbi_cpuidle_domain_sync_state(struct device *dev)
+{
+     /*
+      * All devices have now been attached/probed to the PM domain
+      * topology, hence it's fine to allow domain states to be picked.
+      */
+     sbi_cpuidle_pd_allow_domain_state = true;
+}
+
+#ifdef CONFIG_DT_IDLE_GENPD
+
+struct sbi_pd_provider {
+     struct list_head link;
+     struct device_node *node;
+};
+
+static LIST_HEAD(sbi_pd_providers);
+
+static int sbi_pd_init(struct device_node *np)
+{
+     struct generic_pm_domain *pd;
+     struct sbi_pd_provider *pd_provider;
+     struct dev_power_governor *pd_gov;
+     int ret = -ENOMEM, state_count = 0;
+
+     pd = dt_idle_pd_alloc(np, sbi_dt_parse_state_node);
+     if (!pd)
+             goto out;
...

Regards,
Anup