The DMA controller in Lynxpoint is enumerated as a regular ACPI device now. To
work properly it is using the LPSS root clock as a functional clock. That's why
we have to register the clock device accordingly to the ACPI ID of the DMA
controller. The acpi_lpss.c module is responsible to do the job.
This patch also removes hardcoded name of the DMA device in clk-lpt.c and the
name of the root clock in acpi_lpss.c.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
The excerpt like this:
if (err) {
err = 0;
goto error_out;
}
makes a reader confused even if it's commented. Let's do necessary actions and
return no error explicitly.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Devices on the Intel Lynxpoint Low Power Subsystem (LPSS) have
registers providing access to LTR (Latency Tolerance Reporting)
functionality that allows software to monitor and possibly influence
the aggressiveness of the platform's active-state power management.
For each LPSS device, there are two modes of operation related to LTR,
the auto mode and the software mode. In the auto mode the LTR is
set up by the platform firmware and managed by hardware. Software
can only read the LTR register values to monitor the platform's
behavior. In the software mode it is possible to use LTR to control
the extent to which the platform will use its built-in power
management features.
This changeset adds support for reading the LPSS devices' LTR
registers and exposing their values to user space for monitoring and
diagnostics purposes. It re-uses the MMIO mappings created to access
the LPSS devices' clock registers for reading the values of the LTR
registers and exposes them to user space through sysfs device
attributes. Namely, a new atrribute group, lpss_ltr, is created for
each LPSS device. It contains three new attributes: ltr_mode,
auto_ltr, sw_ltr. The value of the ltr_mode attribute reflects the
LTR mode being used at the moment (software vs auto) and the other
two contain the actual register values (raw) whose meaning depends
on the LTR mode. All of these attributes are read-only.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Devices on the Intel Lynxpoint Low Power Subsystem (LPSS) have some
common features that aren't shared with any other platform devices,
including the clock and LTR (Latency Tolerance Reporting) registers.
It is better to handle those features in common code than to bother
device drivers with doing that (I/O functionality-wise the LPSS
devices are generally compatible with other devices that don't
have those special registers and may be handled by the same drivers).
The clock registers of the LPSS devices are now taken care of by
the special clk-x86-lpss driver, but the MMIO mappings used for
accessing those registers can also be used for accessing the LTR
registers on those devices (LTR support for the Lynxpoint LPSS is
going to be added by a subsequent patch). Thus it is convenient
to add a special ACPI scan handler for the Lynxpoint LPSS devices
that will create the MMIO mappings for accessing the clock (and
LTR in the future) registers and will register the LPSS devices'
clocks, so the clk-x86-lpss driver will only need to take care of
the main Lynxpoint LPSS clock.
Introduce a special ACPI scan handler for Intel Lynxpoint LPSS
devices as described above. This also reduces overhead related to
browsing the ACPI namespace in search of the LPSS devices before the
registration of their clocks, removes some LPSS-specific (and
somewhat ugly) code from acpi_platform.c and shrinks the overall code
size slightly.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Mike Turquette <mturquette@linaro.org>
