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