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Subject[PATCH v3] pinctrl: add support for group and pinmux states
Date
From: Linus Walleij <linus.walleij@linaro.org>

This makes it possible for pin groups and pin muxes to go into
different states, which is especially useful for power management,
both runtime and across suspend/resume.
ChangeLog v2->v3:
- Let the pin controller enumerate the available states for a
group with string names just like it enumerates the groups
themselves.
- Do not mandate any states (these are full-custom) but supply
a bunch of clever presets in <linux/pinctrl/pinctrl.h> that
can be used when applicable.
- Consequental changes to the pinmux interface - muxes use the
named group states.
ChangeLog v1->v2:
- Use a pin controller name instead of the device itself as
parameter to the state set function, as indicated by Stephens
similar patch to config this is more helpful.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
Documentation/pinctrl.txt | 114 +++++++++++++++++++++++++++++++++++++++
drivers/pinctrl/core.c | 86 +++++++++++++++++++++++++++++
drivers/pinctrl/core.h | 3 +
drivers/pinctrl/pinmux.c | 32 +++++++++++
include/linux/pinctrl/pinctrl.h | 44 +++++++++++++++
include/linux/pinctrl/pinmux.h | 7 +++
6 files changed, 286 insertions(+), 0 deletions(-)
diff --git a/Documentation/pinctrl.txt b/Documentation/pinctrl.txt
index 1851f1d..bf50192 100644
--- a/Documentation/pinctrl.txt
+++ b/Documentation/pinctrl.txt
@@ -194,6 +194,96 @@ just a simple example - in practice you may need more entries in your group
structure, for example specific register ranges associated with each group
and so on.

+Pin group states
+================
+
+To simplify handling of specific group states, such as when a group of
+pins need to be deactivated or put in a specific sleep state, the pin controller
+may implement callbacks to enumerate a number of states and select one of
+them. This will for example be called automatically to set a certain pin group
+in active state when the groups are selected for use in a certain pin
+multiplexing configuration (see below). This is a good opportunity to set up
+any default pin configuration (see below) for the pins in a group.
+
+While the driver will have to maintain states for its pin groups internally
+or in the hardware registers, as well as for setting up the pins on boot,
+it will know through these calls if some special action is needed on behalf
+of the users.
+
+For example, a board file may issue:
+
+pinctrl_set_group_state("foo-dev", "i2c7-group", "disabled");
+
+In this case it could be that I2C7 is not used at all in this board, and
+whereas the driver would normally set the I2C pins to pull-up (this happens to
+be required for I2C), in this case since they are not even used on this board,
+it may just as well ground the pins instead and save some power.
+
+The driver will know what to do through this set of callbacks, for example
+if group 3 supports two states "active" and "idle" like this:
+
+static const char *activestate = "active";
+static const char *idlestate = "idle";
+
+static int foo_list_group_states(struct pinctrl_dev *pctldev,
+ unsigned selector,
+ unsigned state)
+{
+ /* Only group three has states */
+ if (selector != 3)
+ return -EINVAL;
+ /* Only two states, 0 and 1 */
+ if (state > 1)
+ return -EINVAL;
+}
+
+static const char foo_get_group_state_name(struct pinctrl_dev *pctldev,
+ unsigned selector,
+ unsigned state)
+{
+
+ if (selector != 3)
+ return -EINVAL;
+ if (state == 0)
+ return activestate;
+ if (state == 1)
+ return idlestate;
+ return -EINVAL;
+}
+
+static int foo_set_group_state(struct pinctrl_dev *pctldev,
+ unsigned selector,
+ unsigned state)
+{
+ if (selector != 3)
+ return -EINVAL;
+ switch(state) {
+ case 0:
+ ...
+ case 1:
+ ...
+ default:
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static struct pinctrl_ops foo_pctrl_ops = {
+ ...
+ .list_group_states = foo_list_group_states,
+ .get_group_state_name = foo_get_group_state_name,
+ .set_group_state = foo_set_group_state,
+};
+
+
+static struct pinctrl_desc foo_desc = {
+ ...
+ .pctlops = &foo_pctrl_ops,
+};
+
+So the core will call .list_group_states() iteratively to get the available
+state names for a group, get names for comparison from .get_group_state_name()
+and then finally set a state using the .set_group_state().

Pin configuration
=================
@@ -1066,3 +1156,27 @@ foo_switch()
}

The above has to be done from process context.
+
+
+Pinmux states
+=============
+
+Pinmuxes can have states just like groups, and in fact setting the state of
+a certain pinmux to a certain named state will in practice loop over the pin
+groups used by the pinmux and set the state for each of these groups. Any calls
+to set the pinmux state will be silently ignored if the pin controller does not
+implement handling of group states.
+
+For example a driver, or centralized power management code for the platform
+(wherever the struct pinmux *pmx pointer is handled) can do power saving calls
+like this:
+
+pinmux_set_state(pmx, "active");
+pinmux_set_state(pmx, "idle");
+pinmux_set_state(pmx, "sleep");
+
+Each call may or may not result in the corresponding pin control driver setting
+pins in special low-power modes, disabling pull-ups or anything else (likely
+pin configuration related). It may also just ignore the call, which is useful
+when the same driver is used with different pin controllers, some of which can
+do something meaningful with this information, some which can't.
diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index 569bdb3..132bbce 100644
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -345,6 +345,92 @@ int pinctrl_get_group_selector(struct pinctrl_dev *pctldev,
return -EINVAL;
}

+/**
+ * pinctrl_get_group_state_selector() - locate a certain group state selector
+ * @pctldev: name of the pin controller to find the group state for
+ * @groupsel: the previously located group selector
+ * @state: the name of the state to locate
+ */
+static int pinctrl_get_group_state_selector(struct pinctrl_dev *pctldev,
+ unsigned groupsel,
+ const char *state)
+{
+ const struct pinctrl_ops *pctlops = pctldev->desc->pctlops;
+ unsigned statesel = 0;
+
+ while (pctlops->list_group_states(pctldev, groupsel, statesel) >= 0) {
+ const char *sname = pctlops->get_group_state_name(pctldev,
+ groupsel,
+ statesel);
+ if (!strcmp(sname, state)) {
+ dev_dbg(pctldev->dev,
+ "found group state selector %u for %s\n",
+ statesel,
+ state);
+ return statesel;
+ }
+
+ statesel++;
+ }
+
+ dev_err(pctldev->dev, "does not have state %s\n", state);
+
+ return -EINVAL;
+}
+
+/**
+ * pinctrl_set_group_state_for_selector() - knowing a groups selector, set its
+ * state
+ * @pctldev: name of the pin controller to find the group state for
+ * @groupsel: the previously located group selector
+ * @state: the name of the state to set
+ */
+int pinctrl_set_group_state_for_selector(struct pinctrl_dev *pctldev,
+ unsigned groupsel,
+ const char *state)
+{
+ const struct pinctrl_ops *ops;
+ int statesel;
+
+ ops = pctldev->desc->pctlops;
+ statesel = pinctrl_get_group_state_selector(pctldev, groupsel, state);
+ if (statesel < 0)
+ return statesel;
+
+ return ops->set_group_state(pctldev, groupsel, statesel);
+}
+
+/**
+ * pinctrl_set_group_state() - set pin group state
+ * @dev_name: name of the pin controller holding the group to change state for
+ * @name: the name of the pin group to change the state of
+ * @state: the new state for the pin group
+ */
+int pinctrl_set_group_state(const char *dev_name,
+ const char *name,
+ const char *state)
+{
+ struct pinctrl_dev *pctldev;
+ const struct pinctrl_ops *ops;
+ int groupsel;
+
+ pctldev = get_pinctrl_dev_from_dev(NULL, dev_name);
+ if (!pctldev)
+ return -EINVAL;
+ ops = pctldev->desc->pctlops;
+
+ if (!ops->list_group_states || !ops->get_group_state_name ||
+ !ops->set_group_state)
+ return 0;
+
+ groupsel = pinctrl_get_group_selector(pctldev, name);
+ if (groupsel < 0)
+ return groupsel;
+
+ return pinctrl_set_group_state_for_selector(pctldev, groupsel, state);
+}
+EXPORT_SYMBOL_GPL(pinctrl_set_group_state);
+
#ifdef CONFIG_DEBUG_FS

static int pinctrl_pins_show(struct seq_file *s, void *what)
diff --git a/drivers/pinctrl/core.h b/drivers/pinctrl/core.h
index 177a331..cbdccb8 100644
--- a/drivers/pinctrl/core.h
+++ b/drivers/pinctrl/core.h
@@ -78,3 +78,6 @@ int pinctrl_get_device_gpio_range(unsigned gpio,
struct pinctrl_gpio_range **outrange);
int pinctrl_get_group_selector(struct pinctrl_dev *pctldev,
const char *pin_group);
+int pinctrl_set_group_state_for_selector(struct pinctrl_dev *pctldev,
+ unsigned groupsel,
+ const char *state);
diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
index a76a348..31c9e1d 100644
--- a/drivers/pinctrl/pinmux.c
+++ b/drivers/pinctrl/pinmux.c
@@ -904,6 +904,38 @@ void pinmux_disable(struct pinmux *pmx)
}
EXPORT_SYMBOL_GPL(pinmux_disable);

+int pinmux_set_state(struct pinmux *pmx, const char *state)
+{
+ struct pinctrl_dev *pctldev = pmx->pctldev;
+ const struct pinctrl_ops *pctlops = pctldev->desc->pctlops;
+ struct pinmux_group *grp;
+ int ret;
+
+ /* Does not implement group states, bail out */
+ if (!pctlops->set_group_state)
+ return 0;
+
+ /*
+ * Loop over the currently used groups for this pinmux and set the
+ * state for each and every one of them.
+ */
+ list_for_each_entry(grp, &pmx->groups, node) {
+ ret = pinctrl_set_group_state_for_selector(pctldev,
+ grp->group_selector,
+ state);
+ if (ret) {
+ dev_err(pctldev->dev, "unable to set state %s for "
+ "group %u on %s\n",
+ state, grp->group_selector,
+ pinctrl_dev_get_name(pctldev));
+ return ret;
+ }
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(pinmux_set_state);
+
int pinmux_check_ops(const struct pinmux_ops *ops)
{
/* Check that we implement required operations */
diff --git a/include/linux/pinctrl/pinctrl.h b/include/linux/pinctrl/pinctrl.h
index 8bd22ee..ca33b84 100644
--- a/include/linux/pinctrl/pinctrl.h
+++ b/include/linux/pinctrl/pinctrl.h
@@ -12,6 +12,23 @@
#ifndef __LINUX_PINCTRL_PINCTRL_H
#define __LINUX_PINCTRL_PINCTRL_H

+/**
+ * Standard pin group states. States are defined by the driver, and names can
+ * be all-custom. However, to avoid duplication of common pin group states,
+ * they are provided here.
+ * @PIN_GROUP_STATE_DISABLED: disabled state
+ * @PIN_GROUP_STATE_ACTIVE: active state, pins are in active use for their
+ * purpose, this should be the default state when pins are muxed in for
+ * example
+ * @PIN_GROUP_STATE_IDLE: the pin group is not actively used now
+ * @PIN_GROUP_STATE_SLEEPING: the pin group is in low-power mode for a longer
+ * period of time
+ */
+#define PIN_GROUP_STATE_DISABLED "disabled"
+#define PIN_GROUP_STATE_ACTIVE "active"
+#define PIN_GROUP_STATE_IDLE "idle"
+#define PIN_GROUP_STATE_SLEEP "sleeping"
+
#ifdef CONFIG_PINCTRL

#include <linux/radix-tree.h>
@@ -69,6 +86,14 @@ struct pinctrl_gpio_range {
* @get_group_name: return the group name of the pin group
* @get_group_pins: return an array of pins corresponding to a certain
* group selector @pins, and the size of the array in @num_pins
+ * @list_group_states: optional callback to list the number of selectable
+ * named group states available for a certain group, the core will begin
+ * on 0 and call this repeatedly as long as it returns >= 0 to enumerate
+ * the states
+ * @get_group_state_name: optional callback to return the name of the pin
+ * group state indicated
+ * @set_group_state: optional callback to set the state of a certain pin
+ * group. Not defining this will make all calls to set state succeed.
* @pin_dbg_show: optional debugfs display hook that will provide per-device
* info for a certain pin in debugfs
*/
@@ -80,6 +105,15 @@ struct pinctrl_ops {
unsigned selector,
const unsigned **pins,
unsigned *num_pins);
+ int (*list_group_states) (struct pinctrl_dev *pctldev,
+ unsigned selector,
+ unsigned state);
+ const char *(*get_group_state_name) (struct pinctrl_dev *pctldev,
+ unsigned selector,
+ unsigned state);
+ int (*set_group_state) (struct pinctrl_dev *pctldev,
+ unsigned selector,
+ unsigned state);
void (*pin_dbg_show) (struct pinctrl_dev *pctldev, struct seq_file *s,
unsigned offset);
};
@@ -120,6 +154,9 @@ extern void pinctrl_remove_gpio_range(struct pinctrl_dev *pctldev,
struct pinctrl_gpio_range *range);
extern const char *pinctrl_dev_get_name(struct pinctrl_dev *pctldev);
extern void *pinctrl_dev_get_drvdata(struct pinctrl_dev *pctldev);
+extern int pinctrl_set_group_state(const char *dev_name,
+ const char *name,
+ const char *state);
#else

struct pinctrl_dev;
@@ -130,6 +167,13 @@ static inline bool pin_is_valid(struct pinctrl_dev *pctldev, int pin)
return pin >= 0;
}

+static inline int pinctrl_set_group_state(const char *dev_name,
+ const char *name,
+ const char *state)
+{
+ return 0;
+}
+
#endif /* !CONFIG_PINCTRL */

#endif /* __LINUX_PINCTRL_PINCTRL_H */
diff --git a/include/linux/pinctrl/pinmux.h b/include/linux/pinctrl/pinmux.h
index 937b3e2..a87be46 100644
--- a/include/linux/pinctrl/pinmux.h
+++ b/include/linux/pinctrl/pinmux.h
@@ -97,6 +97,7 @@ extern struct pinmux * __must_check pinmux_get(struct device *dev, const char *n
extern void pinmux_put(struct pinmux *pmx);
extern int pinmux_enable(struct pinmux *pmx);
extern void pinmux_disable(struct pinmux *pmx);
+extern int pinmux_set_state(struct pinmux *pmx, const char *state);

#else /* !CONFIG_PINMUX */

@@ -137,6 +138,12 @@ static inline void pinmux_disable(struct pinmux *pmx)
{
}

+static inline int pinmux_set_state(struct pinmux *pmx,
+ const char *state)
+{
+ return 0;
+}
+
#endif /* CONFIG_PINMUX */

#endif /* __LINUX_PINCTRL_PINMUX_H */
--
1.7.8


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