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include/device/i2c_simple: add i2c_2ba_read_bytes function 

To read data from an I2C EEPROM that uses 2 byte offsets or any other
I2C device that uses 2 byte offsets, first the two offset bytes are sent
to the device and then the data bytes are read from it. The main
difference to the existing i2c_read_bytes is that that function will
only send one offset byte to the I2C device.

TEST=Reading the contents of an EEPROM on the AMD Chausie board works

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: I224e434bb2654aabef6302c1525112e44c4b21fa
Reviewed-on: https://review.coreboot.org/c/coreboot/+/63791
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Fred Reitberger <reitbergerfred@gmail.com>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
This commit is contained in:
Felix Held 2022-03-08 17:48:59 +01:00
parent 66538e0877
commit 8fbf88fd8c
1 changed files with 28 additions and 0 deletions
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28
src/include/device/i2c_simple.h
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@ -142,4 +142,32 @@ static inline int i2c_writeb(unsigned int bus, uint8_t slave, uint8_t reg,
return i2c_transfer(bus, &seg, 1); return i2c_transfer(bus, &seg, 1);
} }
/**
* Read multi-bytes from an I2C device with two bytes register address/offset
* with two segments in one frame
*
* [start][slave addr][w][register high addr][register low addr]
* [start][slave addr][r][data...][stop]
*/
static inline int i2c_2ba_read_bytes(unsigned int bus, uint8_t slave, uint16_t offset,
uint8_t *data, int len)
{
struct i2c_msg seg[2];
uint8_t eeprom_offset[2];
eeprom_offset[0] = offset >> 8;
eeprom_offset[1] = offset & 0xff;
seg[0].flags = 0;
seg[0].slave = slave;
seg[0].buf = eeprom_offset;
seg[0].len = sizeof(eeprom_offset);
seg[1].flags = I2C_M_RD;
seg[1].slave = slave;
seg[1].buf = data;
seg[1].len = len;
return i2c_transfer(bus, seg, ARRAY_SIZE(seg));
}
#endif /* _DEVICE_I2C_SIMPLE_H_ */ #endif /* _DEVICE_I2C_SIMPLE_H_ */