iio: backend: add devm_iio_backend_get_by_index()

Add a new function to get an IIO backend by its index in the
io-backends device tree property. This is useful for multi-channel
devices that have multiple backends, where looking up by index is
more straightforward than using named backends.

Extract __devm_iio_backend_fwnode_get_by_index() from the existing
__devm_iio_backend_fwnode_get(), taking the index directly as a
parameter. The new public API devm_iio_backend_get_by_index() uses
the index to find the backend reference in the io-backends property,
avoiding the need for io-backend-names.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c
index 10e689f494419b99a47364c258c42a979a332176..138ebebc9c0d07721d14e72e72e25bc017d6d11d 100644 (file)
--- a/drivers/iio/industrialio-backend.c
+++ b/drivers/iio/industrialio-backend.c
@@ -964,23 +964,13 @@ int iio_backend_data_transfer_addr(struct iio_backend *back, u32 address)
 }
 EXPORT_SYMBOL_NS_GPL(iio_backend_data_transfer_addr, "IIO_BACKEND");
 
-static struct iio_backend *__devm_iio_backend_fwnode_get(struct device *dev, const char *name,
-                                                        struct fwnode_handle *fwnode)
+static struct iio_backend *__devm_iio_backend_fwnode_get_by_index(struct device *dev,
+                                                                 struct fwnode_handle *fwnode,
+                                                                 unsigned int index)
 {
        struct iio_backend *back;
-       unsigned int index;
        int ret;
 
-       if (name) {
-               ret = device_property_match_string(dev, "io-backend-names",
-                                                  name);
-               if (ret < 0)
-                       return ERR_PTR(ret);
-               index = ret;
-       } else {
-               index = 0;
-       }
-
        struct fwnode_handle *fwnode_back __free(fwnode_handle) =
                fwnode_find_reference(fwnode, "io-backends", index);
        if (IS_ERR(fwnode_back))
@@ -996,8 +986,7 @@ static struct iio_backend *__devm_iio_backend_fwnode_get(struct device *dev, con
                if (ret)
                        return ERR_PTR(ret);
 
-               if (name)
-                       back->idx = index;
+               back->idx = index;
 
                return back;
        }
@@ -1005,6 +994,24 @@ static struct iio_backend *__devm_iio_backend_fwnode_get(struct device *dev, con
        return ERR_PTR(-EPROBE_DEFER);
 }
 
+static struct iio_backend *__devm_iio_backend_fwnode_get(struct device *dev, const char *name,
+                                                        struct fwnode_handle *fwnode)
+{
+       unsigned int index;
+       int ret;
+
+       if (name) {
+               ret = device_property_match_string(dev, "io-backend-names", name);
+               if (ret < 0)
+                       return ERR_PTR(ret);
+               index = ret;
+       } else {
+               index = 0;
+       }
+
+       return __devm_iio_backend_fwnode_get_by_index(dev, fwnode, index);
+}
+
 /**
  * devm_iio_backend_get - Device managed backend device get
  * @dev: Consumer device for the backend
@@ -1021,6 +1028,22 @@ struct iio_backend *devm_iio_backend_get(struct device *dev, const char *name)
 }
 EXPORT_SYMBOL_NS_GPL(devm_iio_backend_get, "IIO_BACKEND");
 
+/**
+ * devm_iio_backend_get_by_index - Device managed backend device get by index
+ * @dev: Consumer device for the backend
+ * @index: Index of the backend in the io-backends property
+ *
+ * Gets the backend at @index associated with @dev.
+ *
+ * RETURNS:
+ * A backend pointer, negative error pointer otherwise.
+ */
+struct iio_backend *devm_iio_backend_get_by_index(struct device *dev, unsigned int index)
+{
+       return __devm_iio_backend_fwnode_get_by_index(dev, dev_fwnode(dev), index);
+}
+EXPORT_SYMBOL_NS_GPL(devm_iio_backend_get_by_index, "IIO_BACKEND");
+
 /**
  * devm_iio_backend_fwnode_get - Device managed backend firmware node get
  * @dev: Consumer device for the backend

diff --git a/include/linux/iio/backend.h b/include/linux/iio/backend.h
index 4d15c2a9802c1841f121071cbe6933208d207468..3f95ed1fdf9ebb065cee79494a96e1fca6590a29 100644 (file)
--- a/include/linux/iio/backend.h
+++ b/include/linux/iio/backend.h
@@ -261,6 +261,7 @@ int iio_backend_extend_chan_spec(struct iio_backend *back,
 bool iio_backend_has_caps(struct iio_backend *back, u32 caps);
 void *iio_backend_get_priv(const struct iio_backend *conv);
 struct iio_backend *devm_iio_backend_get(struct device *dev, const char *name);
+struct iio_backend *devm_iio_backend_get_by_index(struct device *dev, unsigned int index);
 struct iio_backend *devm_iio_backend_fwnode_get(struct device *dev,
                                                const char *name,
                                                struct fwnode_handle *fwnode);