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authorHeiko Schocher2008-10-15 02:39:47 -0500
committerWolfgang Denk2008-10-18 14:54:02 -0500
commit67b23a322848d828a5e45c0567b72762bfde7abf (patch)
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parentc24853644ddd2dd2e4246b5854a93e6254a14092 (diff)
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I2C: adding new "i2c bus" Command to the I2C Subsystem.
With this Command it is possible to add new I2C Busses, which are behind 1 .. n I2C Muxes. Details see README. Signed-off-by: Heiko Schocher <hs@denx.de>
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@@ -1429,6 +1429,53 @@ The following options need to be configured:
1429 Define this option if you want to use Freescale's I2C driver in 1429 Define this option if you want to use Freescale's I2C driver in
1430 drivers/i2c/fsl_i2c.c. 1430 drivers/i2c/fsl_i2c.c.
1431 1431
1432 CONFIG_I2C_MUX
1433
1434 Define this option if you have I2C devices reached over 1 .. n
1435 I2C Muxes like the pca9544a. This option addes a new I2C
1436 Command "i2c bus [muxtype:muxaddr:muxchannel]" which adds a
1437 new I2C Bus to the existing I2C Busses. If you select the
1438 new Bus with "i2c dev", u-bbot sends first the commandos for
1439 the muxes to activate this new "bus".
1440
1441 CONFIG_I2C_MULTI_BUS must be also defined, to use this
1442 feature!
1443
1444 Example:
1445 Adding a new I2C Bus reached over 2 pca9544a muxes
1446 The First mux with address 70 and channel 6
1447 The Second mux with address 71 and channel 4
1448
1449 => i2c bus pca9544a:70:6:pca9544a:71:4
1450
1451 Use the "i2c bus" command without parameter, to get a list
1452 of I2C Busses with muxes:
1453
1454 => i2c bus
1455 Busses reached over muxes:
1456 Bus ID: 2
1457 reached over Mux(es):
1458 pca9544a@70 ch: 4
1459 Bus ID: 3
1460 reached over Mux(es):
1461 pca9544a@70 ch: 6
1462 pca9544a@71 ch: 4
1463 =>
1464
1465 If you now switch to the new I2C Bus 3 with "i2c dev 3"
1466 u-boot sends First the Commando to the mux@70 to enable
1467 channel 6, and then the Commando to the mux@71 to enable
1468 the channel 4.
1469
1470 After that, you can use the "normal" i2c commands as
1471 usual, to communicate with your I2C devices behind
1472 the 2 muxes.
1473
1474 This option is actually implemented for the bitbanging
1475 algorithm in common/soft_i2c.c and for the Hardware I2C
1476 Bus on the MPC8260. But it should be not so difficult
1477 to add this option to other architectures.
1478
1432 1479
1433- SPI Support: CONFIG_SPI 1480- SPI Support: CONFIG_SPI
1434 1481