Commit 0b52297f authored by Hans de Goede's avatar Hans de Goede Committed by Philipp Zabel

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: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarPhilipp Zabel <p.zabel@pengutronix.de>
parent c15ddec2
...@@ -8,6 +8,7 @@ ...@@ -8,6 +8,7 @@
* the Free Software Foundation; either version 2 of the License, or * the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version. * (at your option) any later version.
*/ */
#include <linux/atomic.h>
#include <linux/device.h> #include <linux/device.h>
#include <linux/err.h> #include <linux/err.h>
#include <linux/export.h> #include <linux/export.h>
...@@ -29,12 +30,16 @@ static LIST_HEAD(reset_controller_list); ...@@ -29,12 +30,16 @@ static LIST_HEAD(reset_controller_list);
* @id: ID of the reset controller in the reset * @id: ID of the reset controller in the reset
* controller device * controller device
* @refcnt: Number of gets of this reset_control * @refcnt: Number of gets of this reset_control
* @shared: Is this a shared (1), or an exclusive (0) reset_control?
* @deassert_cnt: Number of times this reset line has been deasserted
*/ */
struct reset_control { struct reset_control {
struct reset_controller_dev *rcdev; struct reset_controller_dev *rcdev;
struct list_head list; struct list_head list;
unsigned int id; unsigned int id;
unsigned int refcnt; unsigned int refcnt;
int shared;
atomic_t deassert_count;
}; };
/** /**
...@@ -91,9 +96,14 @@ EXPORT_SYMBOL_GPL(reset_controller_unregister); ...@@ -91,9 +96,14 @@ EXPORT_SYMBOL_GPL(reset_controller_unregister);
/** /**
* reset_control_reset - reset the controlled device * reset_control_reset - reset the controlled device
* @rstc: reset controller * @rstc: reset controller
*
* Calling this on a shared reset controller is an error.
*/ */
int reset_control_reset(struct reset_control *rstc) int reset_control_reset(struct reset_control *rstc)
{ {
if (WARN_ON(rstc->shared))
return -EINVAL;
if (rstc->rcdev->ops->reset) if (rstc->rcdev->ops->reset)
return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id); return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
...@@ -104,26 +114,48 @@ EXPORT_SYMBOL_GPL(reset_control_reset); ...@@ -104,26 +114,48 @@ EXPORT_SYMBOL_GPL(reset_control_reset);
/** /**
* reset_control_assert - asserts the reset line * reset_control_assert - asserts the reset line
* @rstc: reset controller * @rstc: reset controller
*
* Calling this on an exclusive reset controller guarantees that the reset
* will be asserted. When called on a shared reset controller the line may
* still be deasserted, as long as other users keep it so.
*
* For shared reset controls a driver cannot expect the hw's registers and
* internal state to be reset, but must be prepared for this to happen.
*/ */
int reset_control_assert(struct reset_control *rstc) int reset_control_assert(struct reset_control *rstc)
{ {
if (rstc->rcdev->ops->assert) if (!rstc->rcdev->ops->assert)
return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id); return -ENOTSUPP;
return -ENOTSUPP; if (rstc->shared) {
if (WARN_ON(atomic_read(&rstc->deassert_count) == 0))
return -EINVAL;
if (atomic_dec_return(&rstc->deassert_count) != 0)
return 0;
}
return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
} }
EXPORT_SYMBOL_GPL(reset_control_assert); EXPORT_SYMBOL_GPL(reset_control_assert);
/** /**
* reset_control_deassert - deasserts the reset line * reset_control_deassert - deasserts the reset line
* @rstc: reset controller * @rstc: reset controller
*
* After calling this function, the reset is guaranteed to be deasserted.
*/ */
int reset_control_deassert(struct reset_control *rstc) int reset_control_deassert(struct reset_control *rstc)
{ {
if (rstc->rcdev->ops->deassert) if (!rstc->rcdev->ops->deassert)
return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id); return -ENOTSUPP;
return -ENOTSUPP; if (rstc->shared) {
if (atomic_inc_return(&rstc->deassert_count) != 1)
return 0;
}
return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
} }
EXPORT_SYMBOL_GPL(reset_control_deassert); EXPORT_SYMBOL_GPL(reset_control_deassert);
...@@ -144,7 +176,7 @@ EXPORT_SYMBOL_GPL(reset_control_status); ...@@ -144,7 +176,7 @@ EXPORT_SYMBOL_GPL(reset_control_status);
static struct reset_control *__reset_control_get( static struct reset_control *__reset_control_get(
struct reset_controller_dev *rcdev, struct reset_controller_dev *rcdev,
unsigned int index) unsigned int index, int shared)
{ {
struct reset_control *rstc; struct reset_control *rstc;
...@@ -152,6 +184,9 @@ static struct reset_control *__reset_control_get( ...@@ -152,6 +184,9 @@ static struct reset_control *__reset_control_get(
list_for_each_entry(rstc, &rcdev->reset_control_head, list) { list_for_each_entry(rstc, &rcdev->reset_control_head, list) {
if (rstc->id == index) { if (rstc->id == index) {
if (WARN_ON(!rstc->shared || !shared))
return ERR_PTR(-EBUSY);
rstc->refcnt++; rstc->refcnt++;
return rstc; return rstc;
} }
...@@ -167,6 +202,7 @@ static struct reset_control *__reset_control_get( ...@@ -167,6 +202,7 @@ static struct reset_control *__reset_control_get(
list_add(&rstc->list, &rcdev->reset_control_head); list_add(&rstc->list, &rcdev->reset_control_head);
rstc->id = index; rstc->id = index;
rstc->refcnt = 1; rstc->refcnt = 1;
rstc->shared = shared;
return rstc; return rstc;
} }
...@@ -185,7 +221,7 @@ static void __reset_control_put(struct reset_control *rstc) ...@@ -185,7 +221,7 @@ static void __reset_control_put(struct reset_control *rstc)
} }
struct reset_control *__of_reset_control_get(struct device_node *node, struct reset_control *__of_reset_control_get(struct device_node *node,
const char *id, int index) const char *id, int index, int shared)
{ {
struct reset_control *rstc; struct reset_control *rstc;
struct reset_controller_dev *r, *rcdev; struct reset_controller_dev *r, *rcdev;
...@@ -235,7 +271,7 @@ struct reset_control *__of_reset_control_get(struct device_node *node, ...@@ -235,7 +271,7 @@ struct reset_control *__of_reset_control_get(struct device_node *node,
} }
/* reset_list_mutex also protects the rcdev's reset_control list */ /* reset_list_mutex also protects the rcdev's reset_control list */
rstc = __reset_control_get(rcdev, rstc_id); rstc = __reset_control_get(rcdev, rstc_id, shared);
mutex_unlock(&reset_list_mutex); mutex_unlock(&reset_list_mutex);
...@@ -265,7 +301,7 @@ static void devm_reset_control_release(struct device *dev, void *res) ...@@ -265,7 +301,7 @@ static void devm_reset_control_release(struct device *dev, void *res)
} }
struct reset_control *__devm_reset_control_get(struct device *dev, struct reset_control *__devm_reset_control_get(struct device *dev,
const char *id, int index) const char *id, int index, int shared)
{ {
struct reset_control **ptr, *rstc; struct reset_control **ptr, *rstc;
...@@ -274,7 +310,8 @@ struct reset_control *__devm_reset_control_get(struct device *dev, ...@@ -274,7 +310,8 @@ struct reset_control *__devm_reset_control_get(struct device *dev,
if (!ptr) if (!ptr)
return ERR_PTR(-ENOMEM); return ERR_PTR(-ENOMEM);
rstc = __of_reset_control_get(dev ? dev->of_node : NULL, id, index); rstc = __of_reset_control_get(dev ? dev->of_node : NULL,
id, index, shared);
if (!IS_ERR(rstc)) { if (!IS_ERR(rstc)) {
*ptr = rstc; *ptr = rstc;
devres_add(dev, ptr); devres_add(dev, ptr);
......
...@@ -13,10 +13,10 @@ int reset_control_deassert(struct reset_control *rstc); ...@@ -13,10 +13,10 @@ int reset_control_deassert(struct reset_control *rstc);
int reset_control_status(struct reset_control *rstc); int reset_control_status(struct reset_control *rstc);
struct reset_control *__of_reset_control_get(struct device_node *node, struct reset_control *__of_reset_control_get(struct device_node *node,
const char *id, int index); const char *id, int index, int shared);
void reset_control_put(struct reset_control *rstc); void reset_control_put(struct reset_control *rstc);
struct reset_control *__devm_reset_control_get(struct device *dev, struct reset_control *__devm_reset_control_get(struct device *dev,
const char *id, int index); const char *id, int index, int shared);
int __must_check device_reset(struct device *dev); int __must_check device_reset(struct device *dev);
...@@ -63,14 +63,14 @@ static inline int device_reset_optional(struct device *dev) ...@@ -63,14 +63,14 @@ static inline int device_reset_optional(struct device *dev)
static inline struct reset_control *__of_reset_control_get( static inline struct reset_control *__of_reset_control_get(
struct device_node *node, struct device_node *node,
const char *id, int index) const char *id, int index, int shared)
{ {
return ERR_PTR(-EINVAL); return ERR_PTR(-EINVAL);
} }
static inline struct reset_control *__devm_reset_control_get( static inline struct reset_control *__devm_reset_control_get(
struct device *dev, struct device *dev,
const char *id, int index) const char *id, int index, int shared)
{ {
return ERR_PTR(-EINVAL); return ERR_PTR(-EINVAL);
} }
...@@ -78,11 +78,17 @@ static inline struct reset_control *__devm_reset_control_get( ...@@ -78,11 +78,17 @@ static inline struct reset_control *__devm_reset_control_get(
#endif /* CONFIG_RESET_CONTROLLER */ #endif /* CONFIG_RESET_CONTROLLER */
/** /**
* reset_control_get - Lookup and obtain a reference to a reset controller. * reset_control_get - Lookup and obtain an exclusive reference to a
* reset controller.
* @dev: device to be reset by the controller * @dev: device to be reset by the controller
* @id: reset line name * @id: reset line name
* *
* Returns a struct reset_control or IS_ERR() condition containing errno. * Returns a struct reset_control or IS_ERR() condition containing errno.
* If this function is called more then once for the same reset_control it will
* return -EBUSY.
*
* See reset_control_get_shared for details on shared references to
* reset-controls.
* *
* Use of id names is optional. * Use of id names is optional.
*/ */
...@@ -92,17 +98,46 @@ static inline struct reset_control *__must_check reset_control_get( ...@@ -92,17 +98,46 @@ static inline struct reset_control *__must_check reset_control_get(
#ifndef CONFIG_RESET_CONTROLLER #ifndef CONFIG_RESET_CONTROLLER
WARN_ON(1); WARN_ON(1);
#endif #endif
return __of_reset_control_get(dev ? dev->of_node : NULL, id, 0); return __of_reset_control_get(dev ? dev->of_node : NULL, id, 0, 0);
} }
static inline struct reset_control *reset_control_get_optional( static inline struct reset_control *reset_control_get_optional(
struct device *dev, const char *id) struct device *dev, const char *id)
{ {
return __of_reset_control_get(dev ? dev->of_node : NULL, id, 0); return __of_reset_control_get(dev ? dev->of_node : NULL, id, 0, 0);
} }
/** /**
* of_reset_control_get - Lookup and obtain a reference to a reset controller. * reset_control_get_shared - Lookup and obtain a shared reference to a
* reset controller.
* @dev: device to be reset by the controller
* @id: reset line name
*
* Returns a struct reset_control or IS_ERR() condition containing errno.
* This function is intended for use with reset-controls which are shared
* between hardware-blocks.
*
* When a reset-control is shared, the behavior of reset_control_assert /
* deassert is changed, the reset-core will keep track of 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. Also see the remark
* about shared reset-controls in the reset_control_assert docs.
*
* 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.
*
* Use of id names is optional.
*/
static inline struct reset_control *reset_control_get_shared(
struct device *dev, const char *id)
{
return __of_reset_control_get(dev ? dev->of_node : NULL, id, 0, 1);
}
/**
* of_reset_control_get - Lookup and obtain an exclusive reference to a
* reset controller.
* @node: device to be reset by the controller * @node: device to be reset by the controller
* @id: reset line name * @id: reset line name
* *
...@@ -113,12 +148,12 @@ static inline struct reset_control *reset_control_get_optional( ...@@ -113,12 +148,12 @@ static inline struct reset_control *reset_control_get_optional(
static inline struct reset_control *of_reset_control_get( static inline struct reset_control *of_reset_control_get(
struct device_node *node, const char *id) struct device_node *node, const char *id)
{ {
return __of_reset_control_get(node, id, 0); return __of_reset_control_get(node, id, 0, 0);
} }
/** /**
* of_reset_control_get_by_index - Lookup and obtain a reference to a reset * of_reset_control_get_by_index - Lookup and obtain an exclusive reference to
* controller by index. * a reset controller by index.
* @node: device to be reset by the controller * @node: device to be reset by the controller
* @index: index of the reset controller * @index: index of the reset controller
* *
...@@ -129,7 +164,7 @@ static inline struct reset_control *of_reset_control_get( ...@@ -129,7 +164,7 @@ static inline struct reset_control *of_reset_control_get(
static inline struct reset_control *of_reset_control_get_by_index( static inline struct reset_control *of_reset_control_get_by_index(
struct device_node *node, int index) struct device_node *node, int index)
{ {
return __of_reset_control_get(node, NULL, index); return __of_reset_control_get(node, NULL, index, 0);
} }
/** /**
...@@ -147,13 +182,13 @@ static inline struct reset_control *__must_check devm_reset_control_get( ...@@ -147,13 +182,13 @@ static inline struct reset_control *__must_check devm_reset_control_get(
#ifndef CONFIG_RESET_CONTROLLER #ifndef CONFIG_RESET_CONTROLLER
WARN_ON(1); WARN_ON(1);
#endif #endif
return __devm_reset_control_get(dev, id, 0); return __devm_reset_control_get(dev, id, 0, 0);
} }
static inline struct reset_control *devm_reset_control_get_optional( static inline struct reset_control *devm_reset_control_get_optional(
struct device *dev, const char *id) struct device *dev, const char *id)
{ {
return __devm_reset_control_get(dev, id, 0); return __devm_reset_control_get(dev, id, 0, 0);
} }
/** /**
...@@ -168,7 +203,38 @@ static inline struct reset_control *devm_reset_control_get_optional( ...@@ -168,7 +203,38 @@ static inline struct reset_control *devm_reset_control_get_optional(
static inline struct reset_control *devm_reset_control_get_by_index( static inline struct reset_control *devm_reset_control_get_by_index(
struct device *dev, int index) struct device *dev, int index)
{ {
return __devm_reset_control_get(dev, NULL, index); return __devm_reset_control_get(dev, NULL, index, 0);
}
/**
* devm_reset_control_get_shared - resource managed reset_control_get_shared()
* @dev: device to be reset by the controller
* @id: reset line name
*
* Managed reset_control_get_shared(). For reset controllers returned from
* this function, reset_control_put() is called automatically on driver detach.
* See reset_control_get_shared() for more information.
*/
static inline struct reset_control *devm_reset_control_get_shared(
struct device *dev, const char *id)
{
return __devm_reset_control_get(dev, id, 0, 1);
}
/**
* devm_reset_control_get_shared_by_index - resource managed
* reset_control_get_shared
* @dev: device to be reset by the controller
* @index: index of the reset controller
*
* Managed reset_control_get_shared(). For reset controllers returned from
* this function, reset_control_put() is called automatically on driver detach.
* See reset_control_get_shared() for more information.
*/
static inline struct reset_control *devm_reset_control_get_shared_by_index(
struct device *dev, int index)
{
return __devm_reset_control_get(dev, NULL, index, 1);
} }
#endif #endif
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