[RFC,v2,1/3] Mailbox: Add support for ACPI

diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
index d83d12c..e2704f5 100644
--- a/drivers/mailbox/mailbox.c
+++ b/drivers/mailbox/mailbox.c
@@ -17,6 +17,7 @@ 
 #include <linux/err.h>
 #include <linux/module.h>
 #include <linux/device.h>
+#include <linux/acpi.h>
 #include <linux/mailbox_client.h>
 #include <linux/mailbox_controller.h>

@@ -273,100 +274,166 @@  int mbox_send_message(struct mbox_chan *chan,
void *mssg)
 }
 EXPORT_SYMBOL_GPL(mbox_send_message);

-/**
- * mbox_request_channel - Request a mailbox channel.
- * @cl: Identity of the client requesting the channel.
- *
- * The Client specifies its requirements and capabilities while asking for
- * a mailbox channel by name. It can't be called from atomic context.
- * The channel is exclusively allocated and can't be used by another
- * client before the owner calls mbox_free_channel.
- * After assignment, any packet received on this channel will be
- * handed over to the client via the 'rx_callback'.
- *
- * Return: Pointer to the channel assigned to the client if successful.
- * ERR_PTR for request failure.
- */
-struct mbox_chan *mbox_request_channel(struct mbox_client *cl)
+static int init_channel(struct mbox_chan *chan,
+ struct mbox_client *cl)
+{
+ unsigned long flags;
+ int ret;
+
+ if (!chan) {
+ pr_err("No mailbox channel specified\n");
+ return -EINVAL;
+ }
+
+ spin_lock_irqsave(&chan->lock, flags);
+ chan->msg_free = 0;
+ chan->msg_count = 0;
+ chan->active_req = NULL;
+ chan->cl = cl;
+
+ if (!cl->tx_tout) /* wait for ever */
+ cl->tx_tout = msecs_to_jiffies(3600000);
+ else
+ cl->tx_tout = msecs_to_jiffies(cl->tx_tout);
+ if (chan->txdone_method == TXDONE_BY_POLL
+ && cl->knows_txdone)
+ chan->txdone_method |= TXDONE_BY_ACK;
+ spin_unlock_irqrestore(&chan->lock, flags);
+
+ ret = chan->mbox->ops->startup(chan);
+ if (ret) {
+ pr_err("Unable to startup the chan\n");
+ mbox_free_channel(chan);
+ chan = ERR_PTR(ret);
+ }
+
+ return ret;
+}
+
+static int get_acpi_mbox_chan(struct mbox_client *cl,
+ struct mbox_chan **chan)
+{
+ struct mbox_controller *mbox;
+ int chan_id, ret, len;
+ char *chan_ptr;
+
+ if (!cl->chan_name)
+ return -ENODEV;
+
+ list_for_each_entry(mbox, &mbox_cons, node) {
+ if (mbox->name) {
+ /*
+ * The cl->chan_name has the format => controller:channel
+ * as described in mailbox_client.h
+ */
+
+ len = strlen(mbox->name);
+ chan_ptr = cl->chan_name + len + 1;
+
+ ret = kstrtou32(cl->chan_name, 0, &chan_id);
+
+ if (ret < 0) {
+ pr_err("Err while parsing mailbox:%s channel idx\n",
+ mbox->name);
+ continue;
+ }
+
+ if (!strncmp(cl->chan_name, mbox->name, len)) {
+ *chan = &mbox->chans[chan_id];
+ return init_channel(*chan, cl);
+ }
+ }
+ }
+
+ return -ENODEV;
+}
+
+static int get_of_mbox_chan(struct mbox_client *cl,
+ struct mbox_chan **chan)
 {
  struct device *dev = cl->dev;
  struct mbox_controller *mbox;
  struct of_phandle_args spec;
- struct mbox_chan *chan;
- unsigned long flags;
  int count, i, ret;

  if (!dev || !dev->of_node) {
  pr_err("%s: No owner device node\n", __func__);
- return ERR_PTR(-ENODEV);
+ return -ENODEV;
  }

  count = of_property_count_strings(dev->of_node, "mbox-names");
  if (count < 0) {
  pr_err("%s: mbox-names property of node '%s' missing\n",
  __func__, dev->of_node->full_name);
- return ERR_PTR(-ENODEV);
+ return -ENODEV;
  }
-
- mutex_lock(&con_mutex);
-
- ret = -ENODEV;
  for (i = 0; i < count; i++) {
  const char *s;

  if (of_property_read_string_index(dev->of_node,
- "mbox-names", i, &s))
+ "mbox-names", i, &s))
  continue;

  if (strcmp(cl->chan_name, s))
  continue;

  if (of_parse_phandle_with_args(dev->of_node,
- "mbox", "#mbox-cells", i, &spec))
+ "mbox", "#mbox-cells", i, &spec))
  continue;

- chan = NULL;
  list_for_each_entry(mbox, &mbox_cons, node)
  if (mbox->dev->of_node == spec.np) {
- chan = mbox->of_xlate(mbox, &spec);
+ *chan = mbox->of_xlate(mbox, &spec);
  break;
  }

  of_node_put(spec.np);

- if (!chan)
+ if (!(*chan))
  continue;

  ret = -EBUSY;
- if (!chan->cl && try_module_get(mbox->dev->driver->owner))
+ if (!(*chan)->cl && acpi_disabled &&
+ try_module_get(mbox->dev->driver->owner))
  break;
  }

  if (i == count) {
  mutex_unlock(&con_mutex);
- return ERR_PTR(ret);
+ return ret;
  }

- spin_lock_irqsave(&chan->lock, flags);
- chan->msg_free = 0;
- chan->msg_count = 0;
- chan->active_req = NULL;
- chan->cl = cl;
- if (!cl->tx_tout) /* wait for ever */
- cl->tx_tout = msecs_to_jiffies(3600000);
+ return init_channel(*chan, cl);
+}
+
+/**
+ * mbox_request_channel - Request a mailbox channel.
+ * @cl: Identity of the client requesting the channel.
+ *
+ * The Client specifies its requirements and capabilities while asking for
+ * a mailbox channel by name. It can't be called from atomic context.
+ * The channel is exclusively allocated and can't be used by another
+ * client before the owner calls mbox_free_channel.
+ * After assignment, any packet received on this channel will be
+ * handed over to the client via the 'rx_callback'.
+ *
+ * Return: Pointer to the channel assigned to the client if successful.
+ * ERR_PTR for request failure.
+ */
+struct mbox_chan *mbox_request_channel(struct mbox_client *cl)
+{
+ struct mbox_chan *chan = NULL;
+ int ret;
+
+ mutex_lock(&con_mutex);
+
+ if (acpi_disabled)
+ ret = get_of_mbox_chan(cl, &chan);
  else
- cl->tx_tout = msecs_to_jiffies(cl->tx_tout);
- if (chan->txdone_method == TXDONE_BY_POLL
- && cl->knows_txdone)
- chan->txdone_method |= TXDONE_BY_ACK;
- spin_unlock_irqrestore(&chan->lock, flags);
+ ret = get_acpi_mbox_chan(cl, &chan);

- ret = chan->mbox->ops->startup(chan);
- if (ret) {
- pr_err("Unable to startup the chan\n");
- mbox_free_channel(chan);
- chan = ERR_PTR(ret);
- }
+ if (ret)
+ pr_err("No mailbox channels found\n");

  mutex_unlock(&con_mutex);
  return chan;
@@ -394,7 +461,9 @@  void mbox_free_channel(struct mbox_chan *chan)
  if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK))
  chan->txdone_method = TXDONE_BY_POLL;

- module_put(chan->mbox->dev->driver->owner);
+ if (chan->mbox->dev)
+ module_put(chan->mbox->dev->driver->owner);
+
  spin_unlock_irqrestore(&chan->lock, flags);
 }
 EXPORT_SYMBOL_GPL(mbox_free_channel);
@@ -422,7 +491,15 @@  int mbox_controller_register(struct mbox_controller *mbox)
  int i, txdone;

  /* Sanity check */
- if (!mbox || !mbox->dev || !mbox->ops || !mbox->num_chans)
+ if (!mbox || !mbox->ops || !mbox->num_chans)
+ return -EINVAL;
+
+ /*
+ * For ACPI platforms, to get mbox->dev, we'd need to
+ * have a fake meaningless entry in the DSDT for the
+ * mailbox controller.
+ */
+ if (acpi_disabled && !mbox->dev)
  return -EINVAL;

  if (mbox->txdone_irq)
diff --git a/include/linux/mailbox_client.h b/include/linux/mailbox_client.h
index bbac2d2..716fbae 100644
--- a/include/linux/mailbox_client.h
+++ b/include/linux/mailbox_client.h
@@ -29,7 +29,7 @@  struct mbox_chan;
  */
 struct mbox_client {
  struct device *dev;
- const char *chan_name;
+ char *chan_name;
  void (*rx_callback)(struct mbox_client *cl, void *mssg);
  void (*tx_done)(struct mbox_client *cl, void *mssg, enum mbox_result r);
  bool tx_block;
diff --git a/include/linux/mailbox_controller.h
b/include/linux/mailbox_controller.h
index cf81e80..06476ef 100644
--- a/include/linux/mailbox_controller.h
+++ b/include/linux/mailbox_controller.h
@@ -78,6 +78,7 @@  struct mbox_controller {
  unsigned period;
  /* Hook to add to the global controller list */
  struct list_head node;
+ char *name;
 } __aligned(32);

 /*