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authorVladimir Zapolskiy <vladimir_zapolskiy@mentor.com>2015-07-27 17:30:50 +0300
committerWolfram Sang <wsa@the-dreams.de>2015-08-10 08:37:36 +0200
commit48e9743dd6483c5fd3f10c8e42c60d52d64b0e27 (patch)
treed657778ce50ddf4a3f088842c0d18d1b29fdd5b3 /drivers/i2c/i2c-core.c
parent611e12ea0f121a31d9e9c4ce2a18a77abc2f28d6 (diff)
i2c: core: add and export of_get_i2c_adapter_by_node() interface
of_find_i2c_adapter_by_node() call requires quite often missing put_device(), and i2c_put_adapter() releases a device locked by i2c_get_adapter() only. In general module_put(adapter->owner) and put_device(dev) are not interchangeable. This is a common error reproduction scenario as a result of the misusage described above (for clearness this is run on iMX6 platform with HDMI and I2C bus drivers compiled as kernel modules): root@mx6q:~# lsmod | grep i2c i2c_imx 10213 0 root@mx6q:~# lsmod | grep dw_hdmi_imx dw_hdmi_imx 3631 0 dw_hdmi 11846 1 dw_hdmi_imx imxdrm 8674 3 dw_hdmi_imx,imx_ipuv3_crtc,imx_ldb drm_kms_helper 113765 5 dw_hdmi,imxdrm,imx_ipuv3_crtc,imx_ldb root@mx6q:~# rmmod dw_hdmi_imx root@mx6q:~# lsmod | grep i2c i2c_imx 10213 -1 ^^^^^ root@mx6q:~# rmmod i2c_imx rmmod: ERROR: Module i2c_imx is in use To fix existing users of these interfaces and to avoid any further confusion and misusage in future, add one more interface of_get_i2c_adapter_by_node(), it is similar to i2c_get_adapter() in sense that an I2C bus device driver found and locked by user can be correctly unlocked by i2c_put_adapter(). Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c/i2c-core.c')
-rw-r--r--drivers/i2c/i2c-core.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index f80992d0a608..07a83f34ed58 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -1371,6 +1371,24 @@ struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
return adapter;
}
EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
+
+/* must call i2c_put_adapter() when done with returned i2c_adapter device */
+struct i2c_adapter *of_get_i2c_adapter_by_node(struct device_node *node)
+{
+ struct i2c_adapter *adapter;
+
+ adapter = of_find_i2c_adapter_by_node(node);
+ if (!adapter)
+ return NULL;
+
+ if (!try_module_get(adapter->owner)) {
+ put_device(&adapter->dev);
+ adapter = NULL;
+ }
+
+ return adapter;
+}
+EXPORT_SYMBOL(of_get_i2c_adapter_by_node);
#else
static void of_i2c_register_devices(struct i2c_adapter *adap) { }
#endif /* CONFIG_OF */