[PATCH 02/11] mux: core: Add support for getting a mux controller on a non DT platform

Hans de Goede
2017-09-01T21:51:56Z

On non DT platforms we cannot get the mux_chip by pnode. Other subsystems
(regulator, clock, pwm) have the same problem and solve this by allowing
platform / board-setup code to add entries to a lookup table and then use
this table to look things up.

This commit adds support for getting a mux controller on a non DT platform
following this pattern. It is based on a simplified version of the pwm
subsys lookup code, the dev_id and mux_name parts of a lookup table entry
are mandatory in the mux-core implementation.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
drivers/mux/core.c | 96 +++++++++++++++++++++++++++++++++++++++++++-
include/linux/mux/consumer.h | 11 +++++
2 files changed, 106 insertions(+), 1 deletion(-)

diff --git a/drivers/mux/core.c b/drivers/mux/core.c
index 6142493c327b..8864cc745506 100644
--- a/drivers/mux/core.c
+++ b/drivers/mux/core.c
@@ -24,6 +24,9 @@
#include <linux/of_platform.h>
#include <linux/slab.h>

+static DEFINE_MUTEX(mux_lookup_lock);
+static LIST_HEAD(mux_lookup_list);
+
/*
* The idle-as-is "state" is not an actual state that may be selected, it
* only implies that the state should not be changed. So, use that state
@@ -408,6 +411,23 @@ int mux_control_deselect(struct mux_control *mux)
}
EXPORT_SYMBOL_GPL(mux_control_deselect);

+static int parent_name_match(struct device *dev, const void *data)
+{
+ const char *parent_name = dev_name(dev->parent);
+ const char *name = data;
+
+ return strcmp(parent_name, name) == 0;
+}
+
+static struct mux_chip *mux_chip_get_by_name(const char *name)
+{
+ struct device *dev;
+
+ dev = class_find_device(&mux_class, NULL, name, parent_name_match);
+
+ return dev ? to_mux_chip(dev) : NULL;
+}
+
static int of_dev_node_match(struct device *dev, const void *data)
{
return dev->of_node == data;
@@ -479,6 +499,42 @@ static struct mux_control *of_mux_control_get(struct device *dev,
}

/**
+ * mux_add_table() - register PWM device consumers
+ * @table: array of consumers to register
+ * @num: number of consumers in table
+ */
+void mux_add_table(struct mux_lookup *table, size_t num)
+{
+ mutex_lock(&mux_lookup_lock);
+
+ while (num--) {
+ list_add_tail(&table->list, &mux_lookup_list);
+ table++;
+ }
+
+ mutex_unlock(&mux_lookup_lock);
+}
+EXPORT_SYMBOL_GPL(mux_add_table);
+
+/**
+ * mux_remove_table() - unregister PWM device consumers
+ * @table: array of consumers to unregister
+ * @num: number of consumers in table
+ */
+void mux_remove_table(struct mux_lookup *table, size_t num)
+{
+ mutex_lock(&mux_lookup_lock);
+
+ while (num--) {
+ list_del(&table->list);
+ table++;
+ }
+
+ mutex_unlock(&mux_lookup_lock);
+}
+EXPORT_SYMBOL_GPL(mux_remove_table);
+
+/**
* mux_control_get() - Get the mux-control for a device.
* @dev: The device that needs a mux-control.
* @mux_name: The name identifying the mux-control.
@@ -487,11 +543,49 @@ static struct mux_control *of_mux_control_get(struct device *dev,
*/
struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
{
+ struct mux_lookup *m, *chosen = NULL;
+ const char *dev_id = dev_name(dev);
+ struct mux_chip *mux_chip;
+
/* look up via DT first */
if (IS_ENABLED(CONFIG_OF) && dev->of_node)
return of_mux_control_get(dev, mux_name);

- return ERR_PTR(-ENODEV);
+ /*
+ * For non DT we look up the provider in the static table typically
+ * provided by board setup code.
+ *
+ * If a match is found, the provider mux chip is looked up by name
+ * and a mux-control is requested using the table provided index.
+ */
+ mutex_lock(&mux_lookup_lock);
+ list_for_each_entry(m, &mux_lookup_list, list) {
+ if (WARN_ON(!m->dev_id || !m->mux_name || !m->provider))
+ continue;
+
+ if (strcmp(m->dev_id, dev_id) == 0 &&
+ strcmp(m->mux_name, mux_name) == 0) {
+ chosen = m;
+ break;
+ }
+ }
+ mutex_unlock(&mux_lookup_lock);
+
+ if (!chosen)
+ return ERR_PTR(-ENODEV);
+
+ mux_chip = mux_chip_get_by_name(chosen->provider);
+ if (!mux_chip)
+ return ERR_PTR(-EPROBE_DEFER);
+
+ if (chosen->index >= mux_chip->controllers) {
+ dev_err(dev, "Mux lookup table index out of bounds %u >= %u\n",
+ chosen->index, mux_chip->controllers);
+ put_device(&mux_chip->dev);
+ return ERR_PTR(-EINVAL);
+ }
+
+ return &mux_chip->mux[chosen->index];
}
EXPORT_SYMBOL_GPL(mux_control_get);

diff --git a/include/linux/mux/consumer.h b/include/linux/mux/consumer.h
index ea96d4c82be7..912dd48a3a5d 100644
--- a/include/linux/mux/consumer.h
+++ b/include/linux/mux/consumer.h
@@ -18,6 +18,17 @@
struct device;
struct mux_control;

+struct mux_lookup {
+ struct list_head list;
+ const char *provider;
+ unsigned int index;
+ const char *dev_id;
+ const char *mux_name;
+};
+
+void mux_add_table(struct mux_lookup *table, size_t num);
+void mux_remove_table(struct mux_lookup *table, size_t num);
+
unsigned int mux_control_states(struct mux_control *mux);
int __must_check mux_control_select(struct mux_control *mux,
unsigned int state);
--
2.13.5