diff mbox

[v2,1/2] Documentation: dt: add bindings for ti-cpufreq

Message ID 20160901025328.376-2-d-gerlach@ti.com (mailing list archive)
State New, archived
Headers show

Commit Message

Dave Gerlach Sept. 1, 2016, 2:53 a.m. UTC
Add the device tree bindings document for the TI CPUFreq/OPP driver
on AM33xx, AM43xx, DRA7, and AM57 SoCs. The operating-points-v2 binding
allows us to provide an opp-supported-hw property for each OPP to define
when it is available. This driver is responsible for reading and parsing
registers to determine which OPPs can be selectively enabled based
on the specific SoC in use by matching against the opp-supported-hw
data.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
---
v1->v2:
	- Dropped all driver/linux specific documentation
	- Fixed some typos
	- Add new compatibles for each SoC family to match against
	- Switched to use am335x example to better demonstrate field one of
	  opp-supported-hw.

 .../devicetree/bindings/cpufreq/ti-cpufreq.txt     | 130 +++++++++++++++++++++
 1 file changed, 130 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt

Comments

Viresh Kumar Sept. 7, 2016, 5:12 a.m. UTC | #1
On 31-08-16, 21:53, Dave Gerlach wrote:
> +In 'operating-points-v2' table:
> +- compatible: Should be
> +	- 'operating-points-v2-ti-am3352-cpu' for am335x SoCs
> +	- 'operating-points-v2-ti-am4372-cpu' for am43xx SoCs
> +	- 'operating-points-v2-ti-dra7-cpu' for dra7xx/am57xx SoCs

Why do you need SoC specific compatible here? Are you defining new
fields in OPP tables for your SoC ? How are the tables for your case
going to differ from the ones using "operating-points-v2" compatible
string?
Dave Gerlach Sept. 7, 2016, 2:36 p.m. UTC | #2
On 09/07/2016 12:12 AM, Viresh Kumar wrote:
> On 31-08-16, 21:53, Dave Gerlach wrote:
>> +In 'operating-points-v2' table:
>> +- compatible: Should be
>> +	- 'operating-points-v2-ti-am3352-cpu' for am335x SoCs
>> +	- 'operating-points-v2-ti-am4372-cpu' for am43xx SoCs
>> +	- 'operating-points-v2-ti-dra7-cpu' for dra7xx/am57xx SoCs
>
> Why do you need SoC specific compatible here? Are you defining new
> fields in OPP tables for your SoC ? How are the tables for your case
> going to differ from the ones using "operating-points-v2" compatible
> string?
>

I thought you had suggested that I do this in your comments from v1, but 
I guess that was dependent on whether or not I put the properties I have 
inserted into the cpu node into the operating-points table instead. I 
still have gotten no comments from any DT maintainers so I left it as 
is. I am still not sure if that is acceptable.

Regards,
Dave
Viresh Kumar Sept. 8, 2016, 3:35 a.m. UTC | #3
On 07-09-16, 09:36, Dave Gerlach wrote:
> On 09/07/2016 12:12 AM, Viresh Kumar wrote:
> >On 31-08-16, 21:53, Dave Gerlach wrote:
> >>+In 'operating-points-v2' table:
> >>+- compatible: Should be
> >>+	- 'operating-points-v2-ti-am3352-cpu' for am335x SoCs
> >>+	- 'operating-points-v2-ti-am4372-cpu' for am43xx SoCs
> >>+	- 'operating-points-v2-ti-dra7-cpu' for dra7xx/am57xx SoCs
> >
> >Why do you need SoC specific compatible here? Are you defining new
> >fields in OPP tables for your SoC ? How are the tables for your case
> >going to differ from the ones using "operating-points-v2" compatible
> >string?
> >
> 
> I thought you had suggested that I do this in your comments from v1, but I
> guess that was dependent on whether or not I put the properties I have
> inserted into the cpu node into the operating-points table instead.

Yes.

> I still
> have gotten no comments from any DT maintainers so I left it as is. I am
> still not sure if that is acceptable.

@Rob: Can you please share your views on the new properties being
added to the CPU node ?
Dave Gerlach Sept. 12, 2016, 8:56 p.m. UTC | #4
Rob,
On 09/07/2016 10:35 PM, Viresh Kumar wrote:
> On 07-09-16, 09:36, Dave Gerlach wrote:
>> On 09/07/2016 12:12 AM, Viresh Kumar wrote:
>>> On 31-08-16, 21:53, Dave Gerlach wrote:
>>>> +In 'operating-points-v2' table:
>>>> +- compatible: Should be
>>>> +	- 'operating-points-v2-ti-am3352-cpu' for am335x SoCs
>>>> +	- 'operating-points-v2-ti-am4372-cpu' for am43xx SoCs
>>>> +	- 'operating-points-v2-ti-dra7-cpu' for dra7xx/am57xx SoCs
>>>
>>> Why do you need SoC specific compatible here? Are you defining new
>>> fields in OPP tables for your SoC ? How are the tables for your case
>>> going to differ from the ones using "operating-points-v2" compatible
>>> string?
>>>
>>
>> I thought you had suggested that I do this in your comments from v1, but I
>> guess that was dependent on whether or not I put the properties I have
>> inserted into the cpu node into the operating-points table instead.
>
> Yes.
>
>> I still
>> have gotten no comments from any DT maintainers so I left it as is. I am
>> still not sure if that is acceptable.
>
> @Rob: Can you please share your views on the new properties being
> added to the CPU node ?
>

I am fine moving the properties in the operating-points-v2 node or 
leaving it as is, whichever is preferred.

Viresh, thanks for your comments.

Regards,
Dave
Rob Herring (Arm) Sept. 19, 2016, 9:14 p.m. UTC | #5
On Wed, Aug 31, 2016 at 09:53:27PM -0500, Dave Gerlach wrote:
> Add the device tree bindings document for the TI CPUFreq/OPP driver
> on AM33xx, AM43xx, DRA7, and AM57 SoCs. The operating-points-v2 binding
> allows us to provide an opp-supported-hw property for each OPP to define
> when it is available. This driver is responsible for reading and parsing
> registers to determine which OPPs can be selectively enabled based
> on the specific SoC in use by matching against the opp-supported-hw
> data.

Sorry, for the delay. Missed this somehow.

> 
> Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
> ---
> v1->v2:
> 	- Dropped all driver/linux specific documentation
> 	- Fixed some typos
> 	- Add new compatibles for each SoC family to match against
> 	- Switched to use am335x example to better demonstrate field one of
> 	  opp-supported-hw.
> 
>  .../devicetree/bindings/cpufreq/ti-cpufreq.txt     | 130 +++++++++++++++++++++
>  1 file changed, 130 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt
> 
> diff --git a/Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt b/Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt
> new file mode 100644
> index 000000000000..6276ae494121
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt
> @@ -0,0 +1,130 @@
> +TI CPUFreq and OPP bindings
> +================================
> +
> +Certain TI SoCs, like those in the am335x, am437x, am57xx, and dra7xx
> +families support different OPPs depending on the silicon variant in use.
> +The ti_cpufreq driver can use revision and an efuse value from the SoC to
> +provide the OPP framework with supported hardware information. This is
> +used to determine which OPPs from the operating-points-v2 table get enabled
> +when it is parsed by the OPP framework.
> +
> +Required properties:
> +--------------------
> +In 'cpus' nodes:
> +- operating-points-v2: Phandle to the operating-points-v2 table to use.
> +- ti,syscon-efuse: Syscon phandle, offset to efuse register, efuse register
> +		   mask, and efuse register shift to get the relevant bits
> +		   that describe OPP availability.
> +- ti,syscon-rev: Syscon and offset used to look up revision value on SoC.

These have nothing to do with a cpu, so they don't belong here. Maybe 
the first is a property of an OPP table, but the second certainly is 
not.

> +
> +In 'operating-points-v2' table:
> +- compatible: Should be
> +	- 'operating-points-v2-ti-am3352-cpu' for am335x SoCs
> +	- 'operating-points-v2-ti-am4372-cpu' for am43xx SoCs
> +	- 'operating-points-v2-ti-dra7-cpu' for dra7xx/am57xx SoCs
> +
> +- opp-supported-hw: Two bitfields indicating:
> +	1. Which revision of the SoC the OPP is supported by
> +	2. Which eFuse bits indicate this OPP is available

I tend to think you should handle this with kernel code (bootloader 
really) fixing up the OPP table as necessary rather than putting in DT.

Rob
Dave Gerlach Sept. 20, 2016, 2:19 p.m. UTC | #6
Rob,
On 09/19/2016 04:14 PM, Rob Herring wrote:
> On Wed, Aug 31, 2016 at 09:53:27PM -0500, Dave Gerlach wrote:
>> Add the device tree bindings document for the TI CPUFreq/OPP driver
>> on AM33xx, AM43xx, DRA7, and AM57 SoCs. The operating-points-v2 binding
>> allows us to provide an opp-supported-hw property for each OPP to define
>> when it is available. This driver is responsible for reading and parsing
>> registers to determine which OPPs can be selectively enabled based
>> on the specific SoC in use by matching against the opp-supported-hw
>> data.
>
> Sorry, for the delay. Missed this somehow.
>
>>
>> Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
>> ---
>> v1->v2:
>> 	- Dropped all driver/linux specific documentation
>> 	- Fixed some typos
>> 	- Add new compatibles for each SoC family to match against
>> 	- Switched to use am335x example to better demonstrate field one of
>> 	  opp-supported-hw.
>>
>>   .../devicetree/bindings/cpufreq/ti-cpufreq.txt     | 130 +++++++++++++++++++++
>>   1 file changed, 130 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt
>>
>> diff --git a/Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt b/Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt
>> new file mode 100644
>> index 000000000000..6276ae494121
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt
>> @@ -0,0 +1,130 @@
>> +TI CPUFreq and OPP bindings
>> +================================
>> +
>> +Certain TI SoCs, like those in the am335x, am437x, am57xx, and dra7xx
>> +families support different OPPs depending on the silicon variant in use.
>> +The ti_cpufreq driver can use revision and an efuse value from the SoC to
>> +provide the OPP framework with supported hardware information. This is
>> +used to determine which OPPs from the operating-points-v2 table get enabled
>> +when it is parsed by the OPP framework.
>> +
>> +Required properties:
>> +--------------------
>> +In 'cpus' nodes:
>> +- operating-points-v2: Phandle to the operating-points-v2 table to use.
>> +- ti,syscon-efuse: Syscon phandle, offset to efuse register, efuse register
>> +		   mask, and efuse register shift to get the relevant bits
>> +		   that describe OPP availability.
>> +- ti,syscon-rev: Syscon and offset used to look up revision value on SoC.
>
> These have nothing to do with a cpu, so they don't belong here. Maybe
> the first is a property of an OPP table, but the second certainly is
> not.

Yes, I have no issue with this and will move the ti properties into the 
operating points table for v3 of the series.

>
>> +
>> +In 'operating-points-v2' table:
>> +- compatible: Should be
>> +	- 'operating-points-v2-ti-am3352-cpu' for am335x SoCs
>> +	- 'operating-points-v2-ti-am4372-cpu' for am43xx SoCs
>> +	- 'operating-points-v2-ti-dra7-cpu' for dra7xx/am57xx SoCs
>> +
>> +- opp-supported-hw: Two bitfields indicating:
>> +	1. Which revision of the SoC the OPP is supported by
>> +	2. Which eFuse bits indicate this OPP is available
>
> I tend to think you should handle this with kernel code (bootloader
> really) fixing up the OPP table as necessary rather than putting in DT.
>

The operating-points-v2 binding here [1] was designed with doing this in 
mind, and others are using it and the corresponding functionality 
offered by the OPP core to selectively enable OPPs. Why hide this in 
u-boot when we already have kernel framework support to do it?

Thanks for your comments, will send v3 moving the appropriate properties 
into the OPP table.

Regards,
Dave

[1] Documentation/devicetree/bindings/opp/opp.txt

> Rob
>
diff mbox

Patch

diff --git a/Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt b/Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt
new file mode 100644
index 000000000000..6276ae494121
--- /dev/null
+++ b/Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt
@@ -0,0 +1,130 @@ 
+TI CPUFreq and OPP bindings
+================================
+
+Certain TI SoCs, like those in the am335x, am437x, am57xx, and dra7xx
+families support different OPPs depending on the silicon variant in use.
+The ti_cpufreq driver can use revision and an efuse value from the SoC to
+provide the OPP framework with supported hardware information. This is
+used to determine which OPPs from the operating-points-v2 table get enabled
+when it is parsed by the OPP framework.
+
+Required properties:
+--------------------
+In 'cpus' nodes:
+- operating-points-v2: Phandle to the operating-points-v2 table to use.
+- ti,syscon-efuse: Syscon phandle, offset to efuse register, efuse register
+		   mask, and efuse register shift to get the relevant bits
+		   that describe OPP availability.
+- ti,syscon-rev: Syscon and offset used to look up revision value on SoC.
+
+In 'operating-points-v2' table:
+- compatible: Should be
+	- 'operating-points-v2-ti-am3352-cpu' for am335x SoCs
+	- 'operating-points-v2-ti-am4372-cpu' for am43xx SoCs
+	- 'operating-points-v2-ti-dra7-cpu' for dra7xx/am57xx SoCs
+
+- opp-supported-hw: Two bitfields indicating:
+	1. Which revision of the SoC the OPP is supported by
+	2. Which eFuse bits indicate this OPP is available
+
+	A bitwise AND is performed against these values and if any bit
+	matches, the OPP gets enabled.
+
+Example:
+--------
+
+/* From arch/arm/boot/dts/am33xx.dtsi */
+cpus {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	cpu@0 {
+		compatible = "arm,cortex-a8";
+		device_type = "cpu";
+		reg = <0>;
+
+		operating-points-v2 = <&cpu0_opp_table>;
+		ti,syscon-efuse = <&scm_conf 0x7fc 0x1fff 0>;
+		ti,syscon-rev = <&scm_conf 0x600>;
+
+		clocks = <&dpll_mpu_ck>;
+		clock-names = "cpu";
+
+		clock-latency = <300000>; /* From omap-cpufreq driver */
+	};
+};
+
+/*
+ * cpu0 has different OPPs depending on SoC revision and some on revisions
+ * 0x2 and 0x4 have eFuse bits that indicate if they are available or not
+ */
+cpu0_opp_table: opp_table0 {
+	compatible = "operating-points-v2-ti-am3352-cpu";
+
+	/*
+	 * The three following nodes are marked with opp-suspend
+	 * because they can not be enabled simultaneously on a
+	 * single SoC.
+	 */
+	opp50@300000000 {
+		opp-hz = /bits/ 64 <300000000>;
+		opp-microvolt = <950000 931000 969000>;
+		opp-supported-hw = <0x06 0x0010>;
+		opp-suspend;
+	};
+
+	opp100@275000000 {
+		opp-hz = /bits/ 64 <275000000>;
+		opp-microvolt = <1100000 1078000 1122000>;
+		opp-supported-hw = <0x01 0x00FF>;
+		opp-suspend;
+	};
+
+	opp100@300000000 {
+		opp-hz = /bits/ 64 <300000000>;
+		opp-microvolt = <1100000 1078000 1122000>;
+		opp-supported-hw = <0x06 0x0020>;
+		opp-suspend;
+	};
+
+	opp100@500000000 {
+		opp-hz = /bits/ 64 <500000000>;
+		opp-microvolt = <1100000 1078000 1122000>;
+		opp-supported-hw = <0x01 0xFFFF>;
+	};
+
+	opp100@600000000 {
+		opp-hz = /bits/ 64 <600000000>;
+		opp-microvolt = <1100000 1078000 1122000>;
+		opp-supported-hw = <0x06 0x0040>;
+	};
+
+	opp120@600000000 {
+		opp-hz = /bits/ 64 <600000000>;
+		opp-microvolt = <1200000 1176000 1224000>;
+		opp-supported-hw = <0x01 0xFFFF>;
+	};
+
+	opp120@720000000 {
+		opp-hz = /bits/ 64 <720000000>;
+		opp-microvolt = <1200000 1176000 1224000>;
+		opp-supported-hw = <0x06 0x0080>;
+	};
+
+	oppturbo@720000000 {
+		opp-hz = /bits/ 64 <720000000>;
+		opp-microvolt = <1260000 1234800 1285200>;
+		opp-supported-hw = <0x01 0xFFFF>;
+	};
+
+	oppturbo@800000000 {
+		opp-hz = /bits/ 64 <800000000>;
+		opp-microvolt = <1260000 1234800 1285200>;
+		opp-supported-hw = <0x06 0x0100>;
+	};
+
+	oppnitro@1000000000 {
+		opp-hz = /bits/ 64 <1000000000>;
+		opp-microvolt = <1325000 1298500 1351500>;
+		opp-supported-hw = <0x04 0x0200>;
+	};
+};