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i2c: add helpers to ease DMA handling

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One helper checks if DMA is suitable and optionally creates a bounce
buffer, if not. The other function returns the bounce buffer and makes
sure the data is properly copied back to the message.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Wolfram Sang
2017-11-04 21:20:02 +01:00
committed by Wolfram Sang
parent 521a72e1f2
commit e94bc5d18b
2 changed files with 49 additions and 0 deletions
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3
include/linux/i2c.h
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@@ -768,6 +768,9 @@ static inline u8 i2c_8bit_addr_from_msg(const struct i2c_msg *msg)
return (msg->addr << 1) | (msg->flags & I2C_M_RD ? 1 : 0);
}
u8 *i2c_get_dma_safe_msg_buf(struct i2c_msg *msg, unsigned int threshold);
void i2c_release_dma_safe_msg_buf(struct i2c_msg *msg, u8 *buf);
int i2c_handle_smbus_host_notify(struct i2c_adapter *adap, unsigned short addr);
/**
* module_i2c_driver() - Helper macro for registering a modular I2C driver