[PATCH v2 02/10] pwm: Allow chips to support multiple PWMs.

* Russell King - ARM Linux wrote:

On Tue, Feb 07, 2012 at 08:04:00AM +0100, Thierry Reding wrote:

quoted

One of the major problems when converting to a non-global namespace is how to
represent the relationship in code. For device tree this should be easy to do
because it has all the infrastructure in place. For non-device-tree devices I
have no idea yet how this could be done. Perhaps by using something like the
clock API and using names for lookup?

Well, the first step is to make sure that the pwm 'chip' drivers don't
know anything about the global numberspace.

That limits the extent of the global numberspace to the pwm core and
pwm users.  You then don't have to worry about the pwm chip drivers
while you work out how to solve the other half of the problem.

I see. That would mean that pwm_request() gets a global PWM index, looks up
the corresponding PWM chip and device then pass the chip-relative index to
the driver's ops.

I think that can be simplified even further. For instance if the pwm_device
structure contains a pointer to its parent struct pwm_chip, then that can be
used directly to call into the driver's ops. And the ops could be modified to
take a pwm_device instead of the global PWM index. That would be similar to
how struct irq_data is used.

Thierry
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