Hi, On 06/20/2014 10:02 AM, Olof Johansson wrote: > On Fri, Jun 20, 2014 at 12:27 AM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote: >> Hi, >> >> On 06/19/2014 07:18 PM, Olof Johansson wrote: >>> Hi, >>> >>> >>> >>> On Thu, Jun 19, 2014 at 6:04 AM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: >>>> The pwrseq subsystem handles complex power sequences, typically useful >>>> for subsystems that makes use of discoverable buses, like for example >>>> MMC and I2C. >>>> >>>> The pwrseq subsystem is dependant on CONFIG_OF to be able to parse a DT >>>> childnode to find out what power sequence method to bind for a device. >>>> >>>> From the DT childnode, the pwrseq DT parser tries to locate a >>>> "power-method" property, which string is matched towards the list of >>>> supported pwrseq methods. >>>> >>>> Each pwrseq method implements it's own power sequence and interfaces >>>> the pwrseq core through a few callback functions. >>>> >>>> To instantiate a pwrseq method, clients shall use the devm_pwrseq_get() >>>> API. If needed, clients can explicity drop the references to a pwrseq >>>> method using devm_pwrseq_put() API. >>>> >>>> Besides instantiation, the pwrseq API provides clients opportunity to >>>> select a certain power state. In this intial version, PWRSEQ_POWER_ON >>>> and PWRSEQ_POWER_OFF are supported. Those are also mandatory for each >>>> pwrseq method to support. >>>> >>>> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> >>>> --- >>>> .../devicetree/bindings/pwrseq/pwrseq.txt | 48 ++++++ >>>> drivers/Makefile | 2 +- >>>> drivers/pwrseq/Makefile | 2 + >>>> drivers/pwrseq/core.c | 175 ++++++++++++++++++++ >>>> drivers/pwrseq/core.h | 37 +++++ >>>> drivers/pwrseq/method.c | 38 +++++ >>>> include/linux/pwrseq.h | 50 ++++++ >>>> 7 files changed, 351 insertions(+), 1 deletion(-) >>>> create mode 100644 Documentation/devicetree/bindings/pwrseq/pwrseq.txt >>>> create mode 100644 drivers/pwrseq/Makefile >>>> create mode 100644 drivers/pwrseq/core.c >>>> create mode 100644 drivers/pwrseq/core.h >>>> create mode 100644 drivers/pwrseq/method.c >>>> create mode 100644 include/linux/pwrseq.h >>>> >>>> diff --git a/Documentation/devicetree/bindings/pwrseq/pwrseq.txt b/Documentation/devicetree/bindings/pwrseq/pwrseq.txt >>>> new file mode 100644 >>>> index 0000000..80848ae >>>> --- /dev/null >>>> +++ b/Documentation/devicetree/bindings/pwrseq/pwrseq.txt >>>> @@ -0,0 +1,48 @@ >>>> +Power sequence DT bindings >>>> + >>>> +Each power sequence method has a corresponding "power-method" property string. >>>> +This property shall be set in a subnode for a device. That subnode should also >>>> +describe resourses which are specific to that power method. >>>> + >>>> +Do note, power sequences as such isn't encoded through DT. Instead those are >>>> +implemented by each power method. >>>> + >>>> +Required subnode properties: >>>> +- power-method: should contain the string for the power method to bind. >>>> + >>>> + Supported power methods: None. >>>> + >>>> +Example: >>>> + >>>> +Note, the "clock" power method in this example isn't actually supported, but >>>> +used to visualize how a childnode could be described. >>>> + >>>> +// WLAN SDIO channel >>>> +sdi1_per2@80118000 { >>>> + compatible = "arm,pl18x", "arm,primecell"; >>>> + reg = <0x80118000 0x1000>; >>>> + interrupts = <0 50 IRQ_TYPE_LEVEL_HIGH>; >>>> + >>>> + dmas = <&dma 32 0 0x2>, /* Logical - DevToMem */ >>>> + <&dma 32 0 0x0>; /* Logical - MemToDev */ >>>> + dma-names = "rx", "tx"; >>>> + >>>> + clocks = <&prcc_kclk 2 4>, <&prcc_pclk 2 6>; >>>> + clock-names = "sdi", "apb_pclk"; >>>> + >>>> + arm,primecell-periphid = <0x10480180>; >>>> + max-frequency = <100000000>; >>>> + bus-width = <4>; >>>> + non-removable; >>>> + pinctrl-names = "default", "sleep"; >>>> + pinctrl-0 = <&sdi1_default_mode>; >>>> + pinctrl-1 = <&sdi1_sleep_mode>; >>>> + >>>> + status = "okay"; >>>> + >>>> + pwrseq: pwrseq1 { >>>> + power-method = "clock"; >>>> + clocks = <&someclk 1 2>, <&someclk 3 4>; >>>> + clock-names = "pwrseq1", "pwrseq2"; >>>> + }; >>> >>> I am strongly against the subnode approach as a general framework. We >>> don't have a subnode for interrupts, nor for clocks or pinctrl. So why >>> should we have it for the power sequencing? >>> >>> Sure, that fits the linux driver model better, but that's irrelevant >>> w.r.t. describing the hardware. >> >> Actually this is about describing the hardware, when you have e.g. an >> mmc device which needs pwrseq, there will be 2 sets of certain >> resources, ie clocks for the host controller and clocks going directly >> to the mmc device. I think putting those both in the same subnode is >> a BAD idea, so we really do need a subnode to group the pwrseq resources >> together. > > I disagree. > > The clock is the input to the module, and it is what needs to be > enabled for the module to work. It's not the input to some > power-sequence component on the module, or next to the module on the > bus. Right, it is an input to the sdio-module, not to the mmc-host, so its an input to a different piece of hardware (at different ends of the mmc bus), but since the mmc-bus normally is fully discoverable we've no node for the other end of the bus. So from the mmc-host pov, which is the one which needs to bind the pwrseq driver, as that needs to be done before it can probe its bus, this is a different piece of hardware, hence a subnode to the host makes perfect sense. This is in no way part of the host, so certainly it does not belong inside the hosts subnode. > It probably makes sense to not use the standard names for the new > resources. I disagree, being able to use standard names is very useful, and actually is a must if we don't want to have to have special versions of devm_get_clk, and all other devm_get_xxx esp. for pwrseq stuff. Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html