diff options
Diffstat (limited to 'drivers/base')
-rw-r--r-- | drivers/base/power/clock_ops.c | 223 |
1 files changed, 182 insertions, 41 deletions
diff --git a/drivers/base/power/clock_ops.c b/drivers/base/power/clock_ops.c index ced6863a16a5..84d5acb6301b 100644 --- a/drivers/base/power/clock_ops.c +++ b/drivers/base/power/clock_ops.c @@ -23,6 +23,7 @@ enum pce_status { PCE_STATUS_NONE = 0, PCE_STATUS_ACQUIRED, + PCE_STATUS_PREPARED, PCE_STATUS_ENABLED, PCE_STATUS_ERROR, }; @@ -32,9 +33,113 @@ struct pm_clock_entry { char *con_id; struct clk *clk; enum pce_status status; + bool enabled_when_prepared; }; /** + * pm_clk_list_lock - ensure exclusive access for modifying the PM clock + * entry list. + * @psd: pm_subsys_data instance corresponding to the PM clock entry list + * and clk_op_might_sleep count to be modified. + * + * Get exclusive access before modifying the PM clock entry list and the + * clock_op_might_sleep count to guard against concurrent modifications. + * This also protects against a concurrent clock_op_might_sleep and PM clock + * entry list usage in pm_clk_suspend()/pm_clk_resume() that may or may not + * happen in atomic context, hence both the mutex and the spinlock must be + * taken here. + */ +static void pm_clk_list_lock(struct pm_subsys_data *psd) + __acquires(&psd->lock) +{ + mutex_lock(&psd->clock_mutex); + spin_lock_irq(&psd->lock); +} + +/** + * pm_clk_list_unlock - counterpart to pm_clk_list_lock(). + * @psd: the same pm_subsys_data instance previously passed to + * pm_clk_list_lock(). + */ +static void pm_clk_list_unlock(struct pm_subsys_data *psd) + __releases(&psd->lock) +{ + spin_unlock_irq(&psd->lock); + mutex_unlock(&psd->clock_mutex); +} + +/** + * pm_clk_op_lock - ensure exclusive access for performing clock operations. + * @psd: pm_subsys_data instance corresponding to the PM clock entry list + * and clk_op_might_sleep count being used. + * @flags: stored irq flags. + * @fn: string for the caller function's name. + * + * This is used by pm_clk_suspend() and pm_clk_resume() to guard + * against concurrent modifications to the clock entry list and the + * clock_op_might_sleep count. If clock_op_might_sleep is != 0 then + * only the mutex can be locked and those functions can only be used in + * non atomic context. If clock_op_might_sleep == 0 then these functions + * may be used in any context and only the spinlock can be locked. + * Returns -EINVAL if called in atomic context when clock ops might sleep. + */ +static int pm_clk_op_lock(struct pm_subsys_data *psd, unsigned long *flags, + const char *fn) + /* sparse annotations don't work here as exit state isn't static */ +{ + bool atomic_context = in_atomic() || irqs_disabled(); + +try_again: + spin_lock_irqsave(&psd->lock, *flags); + if (!psd->clock_op_might_sleep) { + /* the __release is there to work around sparse limitations */ + __release(&psd->lock); + return 0; + } + + /* bail out if in atomic context */ + if (atomic_context) { + pr_err("%s: atomic context with clock_ops_might_sleep = %d", + fn, psd->clock_op_might_sleep); + spin_unlock_irqrestore(&psd->lock, *flags); + might_sleep(); + return -EPERM; + } + + /* we must switch to the mutex */ + spin_unlock_irqrestore(&psd->lock, *flags); + mutex_lock(&psd->clock_mutex); + + /* + * There was a possibility for psd->clock_op_might_sleep + * to become 0 above. Keep the mutex only if not the case. + */ + if (likely(psd->clock_op_might_sleep)) + return 0; + + mutex_unlock(&psd->clock_mutex); + goto try_again; +} + +/** + * pm_clk_op_unlock - counterpart to pm_clk_op_lock(). + * @psd: the same pm_subsys_data instance previously passed to + * pm_clk_op_lock(). + * @flags: irq flags provided by pm_clk_op_lock(). + */ +static void pm_clk_op_unlock(struct pm_subsys_data *psd, unsigned long *flags) + /* sparse annotations don't work here as entry state isn't static */ +{ + if (psd->clock_op_might_sleep) { + mutex_unlock(&psd->clock_mutex); + } else { + /* the __acquire is there to work around sparse limitations */ + __acquire(&psd->lock); + spin_unlock_irqrestore(&psd->lock, *flags); + } +} + +/** * pm_clk_enable - Enable a clock, reporting any errors * @dev: The device for the given clock * @ce: PM clock entry corresponding to the clock. @@ -43,14 +148,21 @@ static inline void __pm_clk_enable(struct device *dev, struct pm_clock_entry *ce { int ret; - if (ce->status < PCE_STATUS_ERROR) { + switch (ce->status) { + case PCE_STATUS_ACQUIRED: + ret = clk_prepare_enable(ce->clk); + break; + case PCE_STATUS_PREPARED: ret = clk_enable(ce->clk); - if (!ret) - ce->status = PCE_STATUS_ENABLED; - else - dev_err(dev, "%s: failed to enable clk %p, error %d\n", - __func__, ce->clk, ret); + break; + default: + return; } + if (!ret) + ce->status = PCE_STATUS_ENABLED; + else + dev_err(dev, "%s: failed to enable clk %p, error %d\n", + __func__, ce->clk, ret); } /** @@ -64,17 +176,20 @@ static void pm_clk_acquire(struct device *dev, struct pm_clock_entry *ce) ce->clk = clk_get(dev, ce->con_id); if (IS_ERR(ce->clk)) { ce->status = PCE_STATUS_ERROR; + return; + } else if (clk_is_enabled_when_prepared(ce->clk)) { + /* we defer preparing the clock in that case */ + ce->status = PCE_STATUS_ACQUIRED; + ce->enabled_when_prepared = true; + } else if (clk_prepare(ce->clk)) { + ce->status = PCE_STATUS_ERROR; + dev_err(dev, "clk_prepare() failed\n"); + return; } else { - if (clk_prepare(ce->clk)) { - ce->status = PCE_STATUS_ERROR; - dev_err(dev, "clk_prepare() failed\n"); - } else { - ce->status = PCE_STATUS_ACQUIRED; - dev_dbg(dev, - "Clock %pC con_id %s managed by runtime PM.\n", - ce->clk, ce->con_id); - } + ce->status = PCE_STATUS_PREPARED; } + dev_dbg(dev, "Clock %pC con_id %s managed by runtime PM.\n", + ce->clk, ce->con_id); } static int __pm_clk_add(struct device *dev, const char *con_id, @@ -106,9 +221,11 @@ static int __pm_clk_add(struct device *dev, const char *con_id, pm_clk_acquire(dev, ce); - spin_lock_irq(&psd->lock); + pm_clk_list_lock(psd); list_add_tail(&ce->node, &psd->clock_list); - spin_unlock_irq(&psd->lock); + if (ce->enabled_when_prepared) + psd->clock_op_might_sleep++; + pm_clk_list_unlock(psd); return 0; } @@ -239,14 +356,20 @@ static void __pm_clk_remove(struct pm_clock_entry *ce) if (!ce) return; - if (ce->status < PCE_STATUS_ERROR) { - if (ce->status == PCE_STATUS_ENABLED) - clk_disable(ce->clk); - - if (ce->status >= PCE_STATUS_ACQUIRED) { - clk_unprepare(ce->clk); + switch (ce->status) { + case PCE_STATUS_ENABLED: + clk_disable(ce->clk); + fallthrough; + case PCE_STATUS_PREPARED: + clk_unprepare(ce->clk); + fallthrough; + case PCE_STATUS_ACQUIRED: + case PCE_STATUS_ERROR: + if (!IS_ERR(ce->clk)) clk_put(ce->clk); - } + break; + default: + break; } kfree(ce->con_id); @@ -269,7 +392,7 @@ void pm_clk_remove(struct device *dev, const char *con_id) if (!psd) return; - spin_lock_irq(&psd->lock); + pm_clk_list_lock(psd); list_for_each_entry(ce, &psd->clock_list, node) { if (!con_id && !ce->con_id) @@ -280,12 +403,14 @@ void pm_clk_remove(struct device *dev, const char *con_id) goto remove; } - spin_unlock_irq(&psd->lock); + pm_clk_list_unlock(psd); return; remove: list_del(&ce->node); - spin_unlock_irq(&psd->lock); + if (ce->enabled_when_prepared) + psd->clock_op_might_sleep--; + pm_clk_list_unlock(psd); __pm_clk_remove(ce); } @@ -307,19 +432,21 @@ void pm_clk_remove_clk(struct device *dev, struct clk *clk) if (!psd || !clk) return; - spin_lock_irq(&psd->lock); + pm_clk_list_lock(psd); list_for_each_entry(ce, &psd->clock_list, node) { if (clk == ce->clk) goto remove; } - spin_unlock_irq(&psd->lock); + pm_clk_list_unlock(psd); return; remove: list_del(&ce->node); - spin_unlock_irq(&psd->lock); + if (ce->enabled_when_prepared) + psd->clock_op_might_sleep--; + pm_clk_list_unlock(psd); __pm_clk_remove(ce); } @@ -330,13 +457,16 @@ EXPORT_SYMBOL_GPL(pm_clk_remove_clk); * @dev: Device to initialize the list of PM clocks for. * * Initialize the lock and clock_list members of the device's pm_subsys_data - * object. + * object, set the count of clocks that might sleep to 0. */ void pm_clk_init(struct device *dev) { struct pm_subsys_data *psd = dev_to_psd(dev); - if (psd) + if (psd) { INIT_LIST_HEAD(&psd->clock_list); + mutex_init(&psd->clock_mutex); + psd->clock_op_might_sleep = 0; + } } EXPORT_SYMBOL_GPL(pm_clk_init); @@ -372,12 +502,13 @@ void pm_clk_destroy(struct device *dev) INIT_LIST_HEAD(&list); - spin_lock_irq(&psd->lock); + pm_clk_list_lock(psd); list_for_each_entry_safe_reverse(ce, c, &psd->clock_list, node) list_move(&ce->node, &list); + psd->clock_op_might_sleep = 0; - spin_unlock_irq(&psd->lock); + pm_clk_list_unlock(psd); dev_pm_put_subsys_data(dev); @@ -397,23 +528,30 @@ int pm_clk_suspend(struct device *dev) struct pm_subsys_data *psd = dev_to_psd(dev); struct pm_clock_entry *ce; unsigned long flags; + int ret; dev_dbg(dev, "%s()\n", __func__); if (!psd) return 0; - spin_lock_irqsave(&psd->lock, flags); + ret = pm_clk_op_lock(psd, &flags, __func__); + if (ret) + return ret; list_for_each_entry_reverse(ce, &psd->clock_list, node) { - if (ce->status < PCE_STATUS_ERROR) { - if (ce->status == PCE_STATUS_ENABLED) + if (ce->status == PCE_STATUS_ENABLED) { + if (ce->enabled_when_prepared) { + clk_disable_unprepare(ce->clk); + ce->status = PCE_STATUS_ACQUIRED; + } else { clk_disable(ce->clk); - ce->status = PCE_STATUS_ACQUIRED; + ce->status = PCE_STATUS_PREPARED; + } } } - spin_unlock_irqrestore(&psd->lock, flags); + pm_clk_op_unlock(psd, &flags); return 0; } @@ -428,18 +566,21 @@ int pm_clk_resume(struct device *dev) struct pm_subsys_data *psd = dev_to_psd(dev); struct pm_clock_entry *ce; unsigned long flags; + int ret; dev_dbg(dev, "%s()\n", __func__); if (!psd) return 0; - spin_lock_irqsave(&psd->lock, flags); + ret = pm_clk_op_lock(psd, &flags, __func__); + if (ret) + return ret; list_for_each_entry(ce, &psd->clock_list, node) __pm_clk_enable(dev, ce); - spin_unlock_irqrestore(&psd->lock, flags); + pm_clk_op_unlock(psd, &flags); return 0; } |