i2c: core: add and export of_get_i2c_adapter_by_node() interface (48e9743d) · Commits · 戴 / test

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>

drivers/i2c/i2c-core.c

+18 −0

Original line number	Diff line number	Diff line
		@@ -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 */

include/linux/i2c.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -638,6 +638,8 @@ extern struct i2c_client of_find_i2c_device_by_node(struct device_node node);
		/* must call put_device() when done with returned i2c_adapter device */
		extern struct i2c_adapter of_find_i2c_adapter_by_node(struct device_node 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);
		#else

		static inline struct i2c_client of_find_i2c_device_by_node(struct device_node node)
		@@ -649,6 +651,11 @@ static inline struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node
		{
		return NULL;
		}

		static inline struct i2c_adapter of_get_i2c_adapter_by_node(struct device_node node)
		{
		return NULL;
		}
		#endif /* CONFIG_OF */

		#endif /* _LINUX_I2C_H */

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