On 01/26/2014 04:32 PM, Mark Brown wrote:
From: Mark Brown <broonie@xxxxxxxxxx>
There is currently no facility in ACPI to express the hookup of voltage
regulators, the expectation is that the regulators that exist in the
system will be handled transparently by firmware if they need software
control at all. This means that if for some reason the regulator API is
enabled on such a system it should assume that any supplies that devices
need are provided by the system at all relevant times without any software
intervention.
Tell the regulator core to make this assumption by calling
regulator_has_full_constraints(). Do this as soon as we know we are using
ACPI so that the information is available to the regulator core as early
as possible. This will cause the regulator core to pretend that there is
an always on regulator supplying any supply that is requested but that has
not otherwise been mapped which is the behaviour expected on a system with
ACPI.
Should the ability to specify regulators be added in future revisions of
ACPI then once we have support for ACPI mappings in the kernel the same
assumptions will apply. It is also likely that systems will default to a
mode of operation which does not require any interpretation of these
mappings in order to be compatible with existing operating system releases
so it should remain safe to make these assumptions even if the mappings
exist but are not supported by the kernel.
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
---
drivers/acpi/bus.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 384da5ab5955..fcb59c21c68d 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -33,6 +33,7 @@
#include <linux/proc_fs.h>
#include <linux/acpi.h>
#include <linux/slab.h>
+#include <linux/regulator/machine.h>
#ifdef CONFIG_X86
#include <asm/mpspec.h>
#endif
@@ -509,6 +510,14 @@ void __init acpi_early_init(void)
goto error0;
}
+ /*
+ * If the system is using ACPI then we can be reasonably
+ * confident that any regulators are managed by the firmware
+ * so tell the regulator core it has everything it needs to
+ * know.
+ */
+ regulator_has_full_constraints();
+
return;
error0:
Couple of scenarios where I don't entirely see how this is expected to work.
- A system which uses CPU cards which sit on a carrier card. The CPU is shared
across multiple carrier cards, and built by an OEM. It supports and uses ACPI,
but ACPI only knows about the CPU card and not the carrier cards, and thus does
not know anything about the carrier card power or regulator requirements.
- A system which supports a large number of complex OIR capable cards.
The card connector includes GPIO pins, I2C busses, PCIe busses, and various other
functionality such as SERDES lines. The card functionality is determined by the
card ID and not known by the time the system ships.
- A USB-I2C or USB-SPI adapter connected to a standard PC. Any I2C or SPI device
can be connected to the I2C or SPI ports.
How is the firmware expected to know about the various devices ? Is the answer
"sorry, this scenario is not supported by the kernel" ?
Guenter
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