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On Tegra, we should always use the "new" I2C slave controller, to avoid
issues with the old controller. This was implemented in commit 65a1a0a
"i2c: tegra: Enable new slave mode."
There is currently no driver for the Tegra I2C slave controller upstream.
Additionally, the controller cannot be completely disabled. Instead, we
need to:
a) Set I2C_SL_CNFG_NACK to make the controller automatically NACK any
incoming transactions.
b) The controller's definition of NACK isn't identical to the I2C
protocol's definition. Specifically, it will perform a standard NACK, but
*also* continue to hold the clock line low in expectation of receiving
more data. This can hang the bus, or at least cause transaction timeouts,
if something starts a transaction that matches the controller's slave
address. Since the default address is 0x00, the general call address,
this does occur in practice.
To avoid this, we explicitly program a slave address that is reserved for
future expansion. For current boards, this guarantees the address will
never be used. If a future board ever needs to use this address, we can
add platform data to determine a board-specific safe address. 0xfc is
picked by this patch.
This patch is based on a change previously posted by: Wei Ni <wni@nvidia.com>
http://www.spinics.net/lists/linux-i2c/msg05437.html
In turned based on internal changes by: Bharat Nihalani <bnihalani@nvidia.com>
A semantically equivalent change has been contained in the various
ChromeOS kernels for a while.
I tested this change on top of 3.0-rc2 on Harmony, and interacted with
the WM8903 I2C-based audio codec.
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
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This enables debouncing of the I2C lines. The debounce period is
2 * the debounce register field value, in terms of the I2C block's main
clock. The Tegra TRM indicates that a setting yielding >50nS is
desirable. Hence, a setting of 2 => 4 clocks @ 72MHz => ~55nS.
Signed-off-by: Ken Radtke <kradtke@nvidia.com>
[swarren: Added commit description body,
Fixed 80-column limit, Reverted file permission change]
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
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A repeated start should be used for all but the last msg in an xfer. The
NOSTART flag is for skipping the START frame (addr/rw)
Signed-off-by: Erik Gilling <konkers@android.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
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Re-init the I2C controller when an IRQ arrives with no
I2C_INT_STATUS bits set to indicate why the interrupt was sent.
Storms of such mystery interrupts are infrequently seen.
Dump some more status when these interrupts arrive. Set an error
for the current request and wake up the requester (rather than
timing out the request or possibly silently ignoring the interrupts).
If the I2C block is inside the DVC, also ACK the DVC I2C transfer
done interrupt in the ISR error return path, as is done for the
normal return path.
Signed-off-by: Todd Poynor <toddpoynor@google.com>
[swarren: Fix minor checkpatch whitespace issue, commit tag]
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
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For Tegra i2c controller to function properly new slave mode must be
enabled.
swarren notes:
In particular, I found this was needed when working on enabling the
Tegra audio driver on the Seaboard board. There are two different PCB
layouts for this board; a "clamshell" version, which works just fine
without this change, and the original non-clamshell version, which needs
this change in order for I2C to operate correctly. Without it, I2C
probing fails for some devices, e.g. with:
wm8903 0-001a: Device with ID register 0 is not a WM8903
wm8903 0-001a: asoc: failed to probe CODEC wm8903.0-001a: -19
asoc: failed to instantiate card tegra-wm8903: -19
ALSA device list:
No soundcards found.
Signed-off-by: Rakesh Iyer <riyer@nvidia.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
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Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
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Adds I2C bus driver for nVidia Tegra SoCs. Tegra includes 4 I2C
controllers, one of which is inside the Dynamic Voltage Controller
and has a slightly different register map.
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
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