reset: Add support for shared reset controls
In some SoCs some hw-blocks share a reset control. Add support for this setup by adding new: reset_control_get_shared() devm_reset_control_get_shared() devm_reset_control_get_shared_by_index() methods to get a reset_control. Note that this patch omits adding of_ variants, if these are needed later they can be easily added. This patch also changes the behavior of the existing exclusive reset_control_get() variants, if these are now called more then once for the same reset_control they will return -EBUSY. To catch existing drivers triggering this error (there should not be any) a WARN_ON(1) is added in this path. When a reset_control is shared, the behavior of reset_control_assert / deassert is changed, for shared reset_controls these will work like the clock-enable/disable and regulator-on/off functions. They will keep a deassert_count, and only (re-)assert the reset after reset_control_assert has been called as many times as reset_control_deassert was called. Calling reset_control_assert without first calling reset_control_deassert is not allowed on a shared reset control. Calling reset_control_reset is also not allowed on a shared reset control. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
This commit is contained in:
Hans de Goede
Philipp Zabel
parent
c15ddec2ca
commit
0b52297f22
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@ -8,6 +8,7 @@
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/atomic.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/export.h>
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@ -29,12 +30,16 @@ static LIST_HEAD(reset_controller_list);
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* @id: ID of the reset controller in the reset
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* controller device
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* @refcnt: Number of gets of this reset_control
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* @shared: Is this a shared (1), or an exclusive (0) reset_control?
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* @deassert_cnt: Number of times this reset line has been deasserted
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*/
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struct reset_control {
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struct reset_controller_dev *rcdev;
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struct list_head list;
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unsigned int id;
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unsigned int refcnt;
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int shared;
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atomic_t deassert_count;
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};
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/**
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@ -91,9 +96,14 @@ EXPORT_SYMBOL_GPL(reset_controller_unregister);
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/**
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* reset_control_reset - reset the controlled device
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* @rstc: reset controller
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*
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* Calling this on a shared reset controller is an error.
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*/
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int reset_control_reset(struct reset_control *rstc)
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{
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if (WARN_ON(rstc->shared))
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return -EINVAL;
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if (rstc->rcdev->ops->reset)
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return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
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@ -104,26 +114,48 @@ EXPORT_SYMBOL_GPL(reset_control_reset);
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/**
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* reset_control_assert - asserts the reset line
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* @rstc: reset controller
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*
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* Calling this on an exclusive reset controller guarantees that the reset
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* will be asserted. When called on a shared reset controller the line may
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* still be deasserted, as long as other users keep it so.
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*
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* For shared reset controls a driver cannot expect the hw's registers and
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* internal state to be reset, but must be prepared for this to happen.
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*/
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int reset_control_assert(struct reset_control *rstc)
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{
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if (rstc->rcdev->ops->assert)
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return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
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if (!rstc->rcdev->ops->assert)
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return -ENOTSUPP;
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return -ENOTSUPP;
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if (rstc->shared) {
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if (WARN_ON(atomic_read(&rstc->deassert_count) == 0))
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return -EINVAL;
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if (atomic_dec_return(&rstc->deassert_count) != 0)
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return 0;
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}
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return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
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}
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EXPORT_SYMBOL_GPL(reset_control_assert);
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/**
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* reset_control_deassert - deasserts the reset line
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* @rstc: reset controller
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*
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* After calling this function, the reset is guaranteed to be deasserted.
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*/
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int reset_control_deassert(struct reset_control *rstc)
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{
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if (rstc->rcdev->ops->deassert)
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return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
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if (!rstc->rcdev->ops->deassert)
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return -ENOTSUPP;
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return -ENOTSUPP;
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if (rstc->shared) {
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if (atomic_inc_return(&rstc->deassert_count) != 1)
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return 0;
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}
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return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
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}
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EXPORT_SYMBOL_GPL(reset_control_deassert);
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@ -144,7 +176,7 @@ EXPORT_SYMBOL_GPL(reset_control_status);
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static struct reset_control *__reset_control_get(
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struct reset_controller_dev *rcdev,
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unsigned int index)
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unsigned int index, int shared)
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{
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struct reset_control *rstc;
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@ -152,6 +184,9 @@ static struct reset_control *__reset_control_get(
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list_for_each_entry(rstc, &rcdev->reset_control_head, list) {
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if (rstc->id == index) {
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if (WARN_ON(!rstc->shared || !shared))
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return ERR_PTR(-EBUSY);
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rstc->refcnt++;
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return rstc;
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}
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@ -167,6 +202,7 @@ static struct reset_control *__reset_control_get(
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list_add(&rstc->list, &rcdev->reset_control_head);
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rstc->id = index;
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rstc->refcnt = 1;
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rstc->shared = shared;
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return rstc;
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}
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@ -185,7 +221,7 @@ static void __reset_control_put(struct reset_control *rstc)
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}
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struct reset_control *__of_reset_control_get(struct device_node *node,
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const char *id, int index)
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const char *id, int index, int shared)
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{
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struct reset_control *rstc;
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struct reset_controller_dev *r, *rcdev;
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@ -235,7 +271,7 @@ struct reset_control *__of_reset_control_get(struct device_node *node,
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}
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/* reset_list_mutex also protects the rcdev's reset_control list */
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rstc = __reset_control_get(rcdev, rstc_id);
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rstc = __reset_control_get(rcdev, rstc_id, shared);
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mutex_unlock(&reset_list_mutex);
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@ -265,7 +301,7 @@ static void devm_reset_control_release(struct device *dev, void *res)
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}
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struct reset_control *__devm_reset_control_get(struct device *dev,
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const char *id, int index)
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const char *id, int index, int shared)
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{
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struct reset_control **ptr, *rstc;
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@ -274,7 +310,8 @@ struct reset_control *__devm_reset_control_get(struct device *dev,
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if (!ptr)
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return ERR_PTR(-ENOMEM);
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rstc = __of_reset_control_get(dev ? dev->of_node : NULL, id, index);
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rstc = __of_reset_control_get(dev ? dev->of_node : NULL,
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id, index, shared);
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if (!IS_ERR(rstc)) {
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*ptr = rstc;
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devres_add(dev, ptr);
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@ -13,10 +13,10 @@ int reset_control_deassert(struct reset_control *rstc);
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int reset_control_status(struct reset_control *rstc);
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struct reset_control *__of_reset_control_get(struct device_node *node,
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const char *id, int index);
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const char *id, int index, int shared);
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void reset_control_put(struct reset_control *rstc);
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struct reset_control *__devm_reset_control_get(struct device *dev,
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const char *id, int index);
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const char *id, int index, int shared);
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int __must_check device_reset(struct device *dev);
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@ -63,14 +63,14 @@ static inline int device_reset_optional(struct device *dev)
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static inline struct reset_control *__of_reset_control_get(
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struct device_node *node,
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const char *id, int index)
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const char *id, int index, int shared)
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{
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return ERR_PTR(-EINVAL);
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}
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static inline struct reset_control *__devm_reset_control_get(
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struct device *dev,
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const char *id, int index)
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const char *id, int index, int shared)
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{
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return ERR_PTR(-EINVAL);
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}
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@ -78,11 +78,17 @@ static inline struct reset_control *__devm_reset_control_get(
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#endif /* CONFIG_RESET_CONTROLLER */
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/**
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* reset_control_get - Lookup and obtain a reference to a reset controller.
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* reset_control_get - Lookup and obtain an exclusive reference to a
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* reset controller.
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* @dev: device to be reset by the controller
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* @id: reset line name
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*
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* Returns a struct reset_control or IS_ERR() condition containing errno.
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* If this function is called more then once for the same reset_control it will
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* return -EBUSY.
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*
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* See reset_control_get_shared for details on shared references to
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* reset-controls.
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*
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* Use of id names is optional.
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*/
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@ -92,17 +98,46 @@ static inline struct reset_control *__must_check reset_control_get(
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#ifndef CONFIG_RESET_CONTROLLER
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WARN_ON(1);
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#endif
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return __of_reset_control_get(dev ? dev->of_node : NULL, id, 0);
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return __of_reset_control_get(dev ? dev->of_node : NULL, id, 0, 0);
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}
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static inline struct reset_control *reset_control_get_optional(
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struct device *dev, const char *id)
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{
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return __of_reset_control_get(dev ? dev->of_node : NULL, id, 0);
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return __of_reset_control_get(dev ? dev->of_node : NULL, id, 0, 0);
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}
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/**
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* of_reset_control_get - Lookup and obtain a reference to a reset controller.
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* reset_control_get_shared - Lookup and obtain a shared reference to a
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* reset controller.
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* @dev: device to be reset by the controller
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* @id: reset line name
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*
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* Returns a struct reset_control or IS_ERR() condition containing errno.
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* This function is intended for use with reset-controls which are shared
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* between hardware-blocks.
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*
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* When a reset-control is shared, the behavior of reset_control_assert /
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* deassert is changed, the reset-core will keep track of a deassert_count
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* and only (re-)assert the reset after reset_control_assert has been called
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* as many times as reset_control_deassert was called. Also see the remark
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* about shared reset-controls in the reset_control_assert docs.
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*
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* Calling reset_control_assert without first calling reset_control_deassert
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* is not allowed on a shared reset control. Calling reset_control_reset is
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* also not allowed on a shared reset control.
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*
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* Use of id names is optional.
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*/
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static inline struct reset_control *reset_control_get_shared(
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struct device *dev, const char *id)
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{
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return __of_reset_control_get(dev ? dev->of_node : NULL, id, 0, 1);
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}
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/**
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* of_reset_control_get - Lookup and obtain an exclusive reference to a
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* reset controller.
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* @node: device to be reset by the controller
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* @id: reset line name
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*
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@ -113,12 +148,12 @@ static inline struct reset_control *reset_control_get_optional(
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static inline struct reset_control *of_reset_control_get(
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struct device_node *node, const char *id)
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{
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return __of_reset_control_get(node, id, 0);
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return __of_reset_control_get(node, id, 0, 0);
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}
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/**
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* of_reset_control_get_by_index - Lookup and obtain a reference to a reset
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* controller by index.
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* of_reset_control_get_by_index - Lookup and obtain an exclusive reference to
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* a reset controller by index.
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* @node: device to be reset by the controller
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* @index: index of the reset controller
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*
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@ -129,7 +164,7 @@ static inline struct reset_control *of_reset_control_get(
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static inline struct reset_control *of_reset_control_get_by_index(
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struct device_node *node, int index)
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{
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return __of_reset_control_get(node, NULL, index);
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return __of_reset_control_get(node, NULL, index, 0);
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}
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/**
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@ -147,13 +182,13 @@ static inline struct reset_control *__must_check devm_reset_control_get(
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#ifndef CONFIG_RESET_CONTROLLER
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WARN_ON(1);
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#endif
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return __devm_reset_control_get(dev, id, 0);
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return __devm_reset_control_get(dev, id, 0, 0);
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}
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static inline struct reset_control *devm_reset_control_get_optional(
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struct device *dev, const char *id)
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{
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return __devm_reset_control_get(dev, id, 0);
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return __devm_reset_control_get(dev, id, 0, 0);
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}
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/**
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@ -168,7 +203,38 @@ static inline struct reset_control *devm_reset_control_get_optional(
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static inline struct reset_control *devm_reset_control_get_by_index(
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struct device *dev, int index)
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{
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return __devm_reset_control_get(dev, NULL, index);
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return __devm_reset_control_get(dev, NULL, index, 0);
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}
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/**
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* devm_reset_control_get_shared - resource managed reset_control_get_shared()
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* @dev: device to be reset by the controller
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* @id: reset line name
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*
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* Managed reset_control_get_shared(). For reset controllers returned from
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* this function, reset_control_put() is called automatically on driver detach.
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* See reset_control_get_shared() for more information.
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*/
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static inline struct reset_control *devm_reset_control_get_shared(
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struct device *dev, const char *id)
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{
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return __devm_reset_control_get(dev, id, 0, 1);
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}
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/**
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* devm_reset_control_get_shared_by_index - resource managed
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* reset_control_get_shared
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* @dev: device to be reset by the controller
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* @index: index of the reset controller
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*
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* Managed reset_control_get_shared(). For reset controllers returned from
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* this function, reset_control_put() is called automatically on driver detach.
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* See reset_control_get_shared() for more information.
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*/
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static inline struct reset_control *devm_reset_control_get_shared_by_index(
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struct device *dev, int index)
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{
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return __devm_reset_control_get(dev, NULL, index, 1);
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}
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#endif
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