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In order to optimize performance, limit amount of back and forth
transactions between x86 and PSP. This is done by introduction of
semaphore reservation period - that is window in which x86 isn't
releasing the bus immediately after each I2C transaction.
In order to protect PSP from being starved while waiting for
arbitration, after a programmed time bus is automatically released by a
deferred function.
Signed-off-by: Jan Dabros <jsd@semihalf.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
[wsa: removed an unneeded empty line]
Signed-off-by: Wolfram Sang <wsa@kernel.org>
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Adjust retry period and timeout values for x86-PSP mailbox based on the
typical I2C traffic generated by PSP. In order to limit the possibility
of timeouts, x86 should reduce the interval between retries as well as
increase overall time after which it gives up.
Signed-off-by: Jan Dabros <jsd@semihalf.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
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Simplify code by moving common part to one function.
Signed-off-by: Jan Dabros <jsd@semihalf.com>
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
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Kernel test robot reported incorrect type in argument 1 of readl(), but
more importantly it brought attention that MMIO accessor shouldn't be
used in this case, since req->hdr.status is part of a command-response
buffer in system memory.
Since its value may be altered by PSP outside of the scope of current
thread (somehow similar to IRQ handler case), we need to use
READ_ONCE() to ensure compiler won't optimize this call.
Fix also 'status' variable type to reflect that corresponding field in
command-response buffer is platform-independent u32.
Fixes: 78d5e9e299e3 ("i2c: designware: Add AMD PSP I2C bus support")
Signed-off-by: Jan Dabros <jsd@semihalf.com>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
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Eliminate the following coccicheck warnings:
./drivers/i2c/busses/i2c-designware-amdpsp.c:172:2-3: Unneeded semicolon
./drivers/i2c/busses/i2c-designware-amdpsp.c:245:2-3: Unneeded semicolon
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Reviewed-by: Jan Dabros <jsd@semihalf.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
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Implement an I2C controller sharing mechanism between the host (kernel)
and PSP co-processor on some platforms equipped with AMD Cezanne SoC.
On these platforms we need to implement "software" i2c arbitration.
Default arbitration owner is PSP and kernel asks for acquire as well
as inform about release of the i2c bus via mailbox mechanism.
+---------+
<- ACQUIRE | |
+---------| CPU |\
| | | \ +----------+ SDA
| +---------+ \ | |-------
MAILBOX +--> | I2C-DW | SCL
| +---------+ | |-------
| | | +----------+
+---------| PSP |
<- ACK | |
+---------+
+---------+
<- RELEASE | |
+---------| CPU |
| | | +----------+ SDA
| +---------+ | |-------
MAILBOX +--> | I2C-DW | SCL
| +---------+ / | |-------
| | | / +----------+
+---------| PSP |/
<- ACK | |
+---------+
The solution is similar to i2c-designware-baytrail.c implementation, where
we are using a generic i2c-designware-* driver with a small "wrapper".
In contrary to baytrail semaphore implementation, beside internal
acquire_lock() and release_lock() methods we are also applying quirks to
lock_bus() and unlock_bus() global adapter methods. With this in place
all i2c clients drivers may lock i2c bus for a desired number of i2c
transactions (e.g. write-wait-read) without being aware of that such bus
is shared with another entity.
Modify i2c_dw_probe_lock_support() to select correct semaphore
implementation at runtime, since now we have more than one available.
Configure new matching ACPI ID "AMDI0019" and register
ARBITRATION_SEMAPHORE flag in order to distinguish setup with PSP
arbitration.
Add myself as a reviewer for I2C DesignWare in order to help with reviewing
and testing possible changes touching new i2c-designware-amdpsp.c module.
Signed-off-by: Jan Dabros <jsd@semihalf.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
[wsa: removed unneeded blank line and curly braces]
Signed-off-by: Wolfram Sang <wsa@kernel.org>
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