1 files changed, 228 insertions, 0 deletions
diff --git a/drivers/cpuidle/dt_idle_states.c b/drivers/cpuidle/dt_idle_states.c
new file mode 100644
index 000000000..448bc796b
--- /dev/null
+++ b/drivers/cpuidle/dt_idle_states.c
@@ -0,0 +1,228 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * DT idle states parsing code.
+ *
+ * Copyright (C) 2014 ARM Ltd.
+ * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
+ */
+
+#define pr_fmt(fmt) "DT idle-states: " fmt
+
+#include <linux/cpuidle.h>
+#include <linux/cpumask.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+#include "dt_idle_states.h"
+
+static int init_state_node(struct cpuidle_state *idle_state,
+			   const struct of_device_id *match_id,
+			   struct device_node *state_node)
+{
+	int err;
+	const char *desc;
+
+	/*
+	 * CPUidle drivers are expected to initialize the const void *data
+	 * pointer of the passed in struct of_device_id array to the idle
+	 * state enter function.
+	 */
+	idle_state->enter = match_id->data;
+	/*
+	 * Since this is not a "coupled" state, it's safe to assume interrupts
+	 * won't be enabled when it exits allowing the tick to be frozen
+	 * safely. So enter() can be also enter_s2idle() callback.
+	 */
+	idle_state->enter_s2idle = match_id->data;
+
+	err = of_property_read_u32(state_node, "wakeup-latency-us",
+				   &idle_state->exit_latency);
+	if (err) {
+		u32 entry_latency, exit_latency;
+
+		err = of_property_read_u32(state_node, "entry-latency-us",
+					   &entry_latency);
+		if (err) {
+			pr_debug(" * %pOF missing entry-latency-us property\n",
+				 state_node);
+			return -EINVAL;
+		}
+
+		err = of_property_read_u32(state_node, "exit-latency-us",
+					   &exit_latency);
+		if (err) {
+			pr_debug(" * %pOF missing exit-latency-us property\n",
+				 state_node);
+			return -EINVAL;
+		}
+		/*
+		 * If wakeup-latency-us is missing, default to entry+exit
+		 * latencies as defined in idle states bindings
+		 */
+		idle_state->exit_latency = entry_latency + exit_latency;
+	}
+
+	err = of_property_read_u32(state_node, "min-residency-us",
+				   &idle_state->target_residency);
+	if (err) {
+		pr_debug(" * %pOF missing min-residency-us property\n",
+			     state_node);
+		return -EINVAL;
+	}
+
+	err = of_property_read_string(state_node, "idle-state-name", &desc);
+	if (err)
+		desc = state_node->name;
+
+	idle_state->flags = 0;
+	if (of_property_read_bool(state_node, "local-timer-stop"))
+		idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP;
+	/*
+	 * TODO:
+	 *	replace with kstrdup and pointer assignment when name
+	 *	and desc become string pointers
+	 */
+	strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1);
+	strncpy(idle_state->desc, desc, CPUIDLE_DESC_LEN - 1);
+	return 0;
+}
+
+/*
+ * Check that the idle state is uniform across all CPUs in the CPUidle driver
+ * cpumask
+ */
+static bool idle_state_valid(struct device_node *state_node, unsigned int idx,
+			     const cpumask_t *cpumask)
+{
+	int cpu;
+	struct device_node *cpu_node, *curr_state_node;
+	bool valid = true;
+
+	/*
+	 * Compare idle state phandles for index idx on all CPUs in the
+	 * CPUidle driver cpumask. Start from next logical cpu following
+	 * cpumask_first(cpumask) since that's the CPU state_node was
+	 * retrieved from. If a mismatch is found bail out straight
+	 * away since we certainly hit a firmware misconfiguration.
+	 */
+	for (cpu = cpumask_next(cpumask_first(cpumask), cpumask);
+	     cpu < nr_cpu_ids; cpu = cpumask_next(cpu, cpumask)) {
+		cpu_node = of_cpu_device_node_get(cpu);
+		curr_state_node = of_get_cpu_state_node(cpu_node, idx);
+		if (state_node != curr_state_node)
+			valid = false;
+
+		of_node_put(curr_state_node);
+		of_node_put(cpu_node);
+		if (!valid)
+			break;
+	}
+
+	return valid;
+}
+
+/**
+ * dt_init_idle_driver() - Parse the DT idle states and initialize the
+ *			   idle driver states array
+ * @drv:	  Pointer to CPU idle driver to be initialized
+ * @matches:	  Array of of_device_id match structures to search in for
+ *		  compatible idle state nodes. The data pointer for each valid
+ *		  struct of_device_id entry in the matches array must point to
+ *		  a function with the following signature, that corresponds to
+ *		  the CPUidle state enter function signature:
+ *
+ *		  int (*)(struct cpuidle_device *dev,
+ *			  struct cpuidle_driver *drv,
+ *			  int index);
+ *
+ * @start_idx:    First idle state index to be initialized
+ *
+ * If DT idle states are detected and are valid the state count and states
+ * array entries in the cpuidle driver are initialized accordingly starting
+ * from index start_idx.
+ *
+ * Return: number of valid DT idle states parsed, <0 on failure
+ */
+int dt_init_idle_driver(struct cpuidle_driver *drv,
+			const struct of_device_id *matches,
+			unsigned int start_idx)
+{
+	struct cpuidle_state *idle_state;
+	struct device_node *state_node, *cpu_node;
+	const struct of_device_id *match_id;
+	int i, err = 0;
+	const cpumask_t *cpumask;
+	unsigned int state_idx = start_idx;
+
+	if (state_idx >= CPUIDLE_STATE_MAX)
+		return -EINVAL;
+	/*
+	 * We get the idle states for the first logical cpu in the
+	 * driver mask (or cpu_possible_mask if the driver cpumask is not set)
+	 * and we check through idle_state_valid() if they are uniform
+	 * across CPUs, otherwise we hit a firmware misconfiguration.
+	 */
+	cpumask = drv->cpumask ? : cpu_possible_mask;
+	cpu_node = of_cpu_device_node_get(cpumask_first(cpumask));
+
+	for (i = 0; ; i++) {
+		state_node = of_get_cpu_state_node(cpu_node, i);
+		if (!state_node)
+			break;
+
+		match_id = of_match_node(matches, state_node);
+		if (!match_id) {
+			err = -ENODEV;
+			break;
+		}
+
+		if (!of_device_is_available(state_node)) {
+			of_node_put(state_node);
+			continue;
+		}
+
+		if (!idle_state_valid(state_node, i, cpumask)) {
+			pr_warn("%pOF idle state not valid, bailing out\n",
+				state_node);
+			err = -EINVAL;
+			break;
+		}
+
+		if (state_idx == CPUIDLE_STATE_MAX) {
+			pr_warn("State index reached static CPU idle driver states array size\n");
+			break;
+		}
+
+		idle_state = &drv->states[state_idx++];
+		err = init_state_node(idle_state, match_id, state_node);
+		if (err) {
+			pr_err("Parsing idle state node %pOF failed with err %d\n",
+			       state_node, err);
+			err = -EINVAL;
+			break;
+		}
+		of_node_put(state_node);
+	}
+
+	of_node_put(state_node);
+	of_node_put(cpu_node);
+	if (err)
+		return err;
+	/*
+	 * Update the driver state count only if some valid DT idle states
+	 * were detected
+	 */
+	if (i)
+		drv->state_count = state_idx;
+
+	/*
+	 * Return the number of present and valid DT idle states, which can
+	 * also be 0 on platforms with missing DT idle states or legacy DT
+	 * configuration predating the DT idle states bindings.
+	 */
+	return state_idx - start_idx;
+}
+EXPORT_SYMBOL_GPL(dt_init_idle_driver);