This patch adds an API to automatically enable either hardware components
with existing device drivers or i2c clients. All functions take a device
tree path to find the hardware and will fix up the node status in the
kernel device tree, if it's accessible.
Signed-off-by: Daniel Schultz <d.schultz@xxxxxxxxx>
---
Changes:
v2: Moved from standalone file to oftree.c
Added of_device_is_available, if a driver is disabled
Added of_property_read_u32
Removed Kconfig
Added of_ prefix to function names
Renamed of_autoenable_i2c_by_path to of_autoenable_i2c_by_component
v3: Removed of_find_device_by_node in of_autoenable_device_by_path. If
a driver is disabled in the Kconfig, but enabled in a DTS file,
it can be autoenabled in the kernel DTS. If a driver is enabled,
must also be enabled in the DTS.
common/oftree.c | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
include/of.h | 14 +++++++++
2 files changed, 103 insertions(+)
diff --git a/common/oftree.c b/common/oftree.c
index 09a4455..40eb35f 100644
--- a/common/oftree.c
+++ b/common/oftree.c
@@ -11,6 +11,7 @@
#include <getopt.h>
#include <init.h>
#include <boot.h>
+#include <i2c/i2c.h>
#define MAX_LEVEL 32 /* how deeply nested we will go */
@@ -260,3 +261,91 @@ struct fdt_header *of_get_fixed_tree(struct device_node *node)
return fdt;
}
+
+/**
+ * of_autoenable_device_by_path() - Autoenable a device by a device tree path
+ * @param path Device tree path up from the root to the device
+ * @return 0 on success, -enodev on failure. If no device found in the device
+ * tree.
+ *
+ * This function will search for a device and will enable it in the kernel
+ * device tree, if it exists and is loaded.
+ */
+int of_autoenable_device_by_path(char *path)
+{
+ struct device_node *node;
+ int ret;
+
+ node = of_find_node_by_name(NULL, path);
+ if (!node)
+ node = of_find_node_by_path(path);
+
+ if (!node)
+ return -ENODEV;
+
+ if (!of_device_is_available(node))
+ return -ENODEV;
+
+ ret = of_register_set_status_fixup(path, 1);
+ if (!ret)
+ printf("autoenabled %s\n", node->name);
+ return ret;
+}
+
+/**
+ * of_autoenable_i2c_by_component - Autoenable a i2c client by a device tree path
+ * @param path Device tree path up from the root to the i2c client
+ * @return 0 on success, -enodev on failure. If no i2c client found in the i2c
+ * device tree.
+ *
+ * This function will search for a i2c client, tries to write to the client and
+ * will enable it in the kernel device tree, if it exists and is accessible.
+ */
+int of_autoenable_i2c_by_component(char *path)
+{
+ struct device_node *node;
+ struct i2c_adapter *i2c_adapter;
+ struct i2c_msg msg;
+ char data[1] = {0x0};
+ int ret;
+ uint32_t addr;
+
+ if (!IS_ENABLED(CONFIG_I2C))
+ return -ENODEV;
+
+ node = of_find_node_by_name(NULL, path);
+ if (!node)
+ node = of_find_node_by_path(path);
+ if (!node)
+ return -ENODEV;
+ if (!node->parent)
+ return -ENODEV;
+
+ ret = of_property_read_u32(node, "reg", &addr);
+ if (ret)
+ return -ENODEV;
+
+ i2c_adapter = of_find_i2c_adapter_by_node(node->parent);
+ if (!i2c_adapter)
+ return -ENODEV;
+
+ msg.buf = data;
+ msg.addr = addr;
+ msg.len = 1;
+
+ /* Try to communicate with the i2c client */
+ ret = i2c_transfer(i2c_adapter, &msg, 1);
+ if (ret == -EREMOTEIO)
+ return -ENODEV;
+ if (ret < 1) {
+ printf("failed to autoenable i2c device on address 0x%x with %i\n",
+ addr, ret);
+ return ret;
+ }
+
+ ret = of_register_set_status_fixup(path, 1);
+ if (!ret)
+ printf("autoenabled i2c device %s\n", node->name);
+
+ return ret;
+}
diff --git a/include/of.h b/include/of.h
index 18a4232..9bdbbb5e 100644
--- a/include/of.h
+++ b/include/of.h
@@ -262,6 +262,8 @@ struct device_node *of_find_node_by_alias(struct device_node *root,
const char *alias);
struct device_node *of_find_node_by_path_or_alias(struct device_node *root,
const char *str);
+int of_autoenable_device_by_path(char *path);
+int of_autoenable_i2c_by_component(char *path);
#else
static inline int of_parse_partitions(struct cdev *cdev,
struct device_node *node)
@@ -664,6 +666,18 @@ static inline struct device_node *of_find_node_by_path_or_alias(
{
return NULL;
}
+
+static inline int of_autoenable_i2c_by_path(char *path)
+{
+ return -ENODEV;
+}
+
+static inline int of_autoenable_i2c_by_component(char *path)
+{
+ return -ENODEV;
+}
+
+
#endif
#define for_each_node_by_name(dn, name) \
--
2.7.4
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