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

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Hi,

On 02-09-17 21:13, sathya wrote:
Hi,


On 09/01/2017 02:48 PM, Hans de Goede wrote:
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@xxxxxxxxxx>
---
  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);
Device name usually contains id section (devname.id). Did you take this into consideration ?
+    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
PWM -> MUX

Thank you, good catch, fixed for v2.

Regards,

Hans


+ * @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);

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