[Letux-kernel] [PATCH v2 4/5] ARM: dts: omap5: describe control for ckobuffer

H. Nikolaus Schaller hns at goldelico.com
Mon May 9 13:18:06 CEST 2016


Hi,

> Am 28.04.2016 um 15:23 schrieb Tero Kristo <t-kristo at ti.com>:
> 
> On 28/04/16 12:12, H. Nikolaus Schaller wrote:
>> Hi Tero,
>> 
>>> Am 28.04.2016 um 10:03 schrieb Tero Kristo <t-kristo at ti.com>:
>>> 
>>> On 27/04/16 17:35, H. Nikolaus Schaller wrote:
>>>> HI,
>>>> 
>>>>> Am 27.04.2016 um 16:23 schrieb Peter Ujfalusi <peter.ujfalusi at ti.com>:
>>>>> 
>>>>> On 04/27/2016 05:10 PM, Tero Kristo wrote:
>>>>>> On 27/04/16 16:10, H. Nikolaus Schaller wrote:
>>>>>>> 
>>>>>>>> Am 27.04.2016 um 14:31 schrieb Tero Kristo <t-kristo at ti.com>:
>>>>>>>> 
>>>>>>>> On 27/04/16 09:04, H. Nikolaus Schaller wrote:
>>>>>>>>> 
>>>>>>>>>> Am 26.04.2016 um 19:27 schrieb Tony Lindgren <tony at atomide.com>:
>>>>>>>>>> 
>>>>>>>>>> Tero,
>>>>>>>>>> 
>>>>>>>>>> * H. Nikolaus Schaller <hns at goldelico.com> [160418 11:23]:
>>>>>>>>>>> OMAP5 has a register to control if the ckobuffer is enabled
>>>>>>>>>>> and defines the polarity. ckobuffer is required to drive a twl6040
>>>>>>>>>>> with the system clock. Hence, add the pinctrl,single to the
>>>>>>>>>>> OMAP5 SoC description so that omap5-board-common can
>>>>>>>>>>> set up the ckobuffer as required.
>>>>>>>>>> 
>>>>>>>>>> Is this really a mux or should it be a mux clock?
>>>>>>>>> 
>>>>>>>>> It is a pinmux setting for the clock out buffer to choose what signal
>>>>>>>>> (and polarity) is presented on the fref_xtal_clk pad.
>>>>>>>>> 
>>>>>>>>> The register is part of the CTRL_MODULE_WKUP.
>>>>>>>>> The clock signal is the xtal master clock of the whole SoC.
>>>>>>>>> 
>>>>>>>>> Although there is a bit to choose an alternate clock, there is no
>>>>>>>>> alternate in the OMAP5 silicon.
>>>>>>>>> 
>>>>>>>>> Therefore I would say it is about padconf and not clock or clock mux
>>>>>>>>> related.
>>>>>>>>> 
>>>>>>>>> It just happens to be a clock signal which can be routed to this
>>>>>>>>> pad.
>>>>>>>> 
>>>>>>>> The two could very well be implemented as clock nodes, a mux and a gate.
>>>>>>>> This would describe the hardware functionality better imo, if the
>>>>>>>> assumptions made here are correct. Implementing the control as pinctrl
>>>>>>>> hacks looks rather weird to me.
>>>>>>> 
>>>>>>> Why do you consider it a "pinctrl hack"? IMHO it is not a hack, but 100%
>>>>>>> proper use of pinctrl.
>>>>>> 
>>>>>> It is just the level of abstraction we are talking about here. If it is a
>>>>>> clock we are controlling, we should rather control it as a clock (higher level
>>>>>> abstraction), not a pin.
>>>>> 
>>>>> I second this. I think it is better to have a simple gate clock and handle
>>>>> only CONTROL_CKOBUFFER:CKOBUFFER_CLK_EN (bit 28) only as the other bits does
>>>>> not have real use.
>>>>> 
>>>>> Then we can add clk API support for this. On most OMAP4 devices the clock is
>>>>> always on,
>>>> 
>>>> this is why I am raising the question if we really want to control it on the omap5 or just
>>>> turn it on for all omap5 boards like the omap4 appears to do... I.e. if turning the pin on
>>>> as a pinctrl is IMHO sufficient for all practical purposes.
>>>> 
>>>>> so the board DTS file need to provide a dummy clock, or we can make
>>>>> the high precision clock also as optional (on panda both OMAP4 and twl6040
>>>>> uses the same reference clock).
>>>> 
>>>> Hm. It looks as if implementing this (and clock gating) is beyond my experiences.
>>>> But I am happy to test a proposal on our omap5 board.
>>>> 
>>>> BR and thanks,
>>>> Nikolaus
>>> 
>>> See the inline patch, this implements the fref_xtal_ck. I had to add some kernel code also to cope with the new SCM area, but the same area can now be accessed via syscon also if needed.
>> 
>> Looks interesting, although quite complex to enable a single SoC pad at boot time...
> 
> Yea it gives plenty of other things for you also. syscon, integration with clock framework, etc.
> 
>> 
>> Will asap study how it works and test. And of course report results.
> 
> Thanks, Tero.
> 
>> 
>> Thanks and BR,
>> Nikolaus
>> 
>>> 
>>> From: Tero Kristo <t-kristo at ti.com>
>>> Date: Thu, 28 Apr 2016 11:00:57 +0300
>>> Subject: [PATCH] ARM: omap5: add support for fref_xtal_ck
>>> 
>>> Signed-off-by: Tero Kristo <t-kristo at ti.com>
>>> ---
>>> arch/arm/boot/dts/omap5.dtsi           | 22 ++++++++++++++++++++++
>>> arch/arm/boot/dts/omap54xx-clocks.dtsi | 10 ++++++++++
>>> arch/arm/mach-omap2/control.c          | 20 ++++++++++++++++----
>>> include/linux/clk/ti.h                 |  1 +
>>> 4 files changed, 49 insertions(+), 4 deletions(-)
>>> 
>>> diff --git a/arch/arm/boot/dts/omap5.dtsi b/arch/arm/boot/dts/omap5.dtsi
>>> index 38805eb..bdc6528 100644
>>> --- a/arch/arm/boot/dts/omap5.dtsi
>>> +++ b/arch/arm/boot/dts/omap5.dtsi
>>> @@ -277,6 +277,28 @@
>>> 				pinctrl-single,register-width = <16>;
>>> 				pinctrl-single,function-mask = <0x7fff>;
>>> 			};
>>> +
>>> +			omap5_scm_wkup_pad_conf: omap5_scm_wkup_pad_conf at cda0 {
>>> +				compatible = "ti,omap5-scm-wkup-pad-conf",
>>> +					     "simple-bus";
>>> +				reg = <0xcda0 0x60>;
>>> +				#address-cells = <1>;
>>> +				#size-cells = <1>;
>>> +				ranges = <0 0xcda0 0x60>;
>>> +
>>> +				scm_wkup_pad_conf: scm_conf at 0 {
>>> +					compatible = "syscon", "simple-bus";
>>> +					reg = <0x0 0x60>;
>>> +					#address-cells = <1>;
>>> +					#size-cells = <1>;
>>> +					ranges = <0 0x0 0x60>;
>>> +
>>> +					scm_wkup_pad_conf_clocks: clocks at 0 {
>>> +						#address-cells = <1>;
>>> +						#size-cells = <0>;
>>> +					};
>>> +				};
>>> +			};
>>> 		};
>>> 
>>> 		ocmcram: ocmcram at 40300000 {
>>> diff --git a/arch/arm/boot/dts/omap54xx-clocks.dtsi b/arch/arm/boot/dts/omap54xx-clocks.dtsi
>>> index 83b425f..f970dac 100644
>>> --- a/arch/arm/boot/dts/omap54xx-clocks.dtsi
>>> +++ b/arch/arm/boot/dts/omap54xx-clocks.dtsi
>>> @@ -1388,3 +1388,13 @@
>>> 		reg = <0x021c>;
>>> 	};
>>> };
>>> +
>>> +&scm_wkup_pad_conf_clocks {
>>> +	fref_xtal_ck: fref_xtal_ck {
>>> +		#clocks-cells = <0>;
>>> +		compatible = "ti,gate-clock";
>>> +		clocks = <&sys_clkin>;
>>> +		ti,bit-shift = <28>;
>>> +		reg = <0x14>;
>>> +	};
>>> +};
>>> diff --git a/arch/arm/mach-omap2/control.c b/arch/arm/mach-omap2/control.c
>>> index 1662071..5956641 100644
>>> --- a/arch/arm/mach-omap2/control.c
>>> +++ b/arch/arm/mach-omap2/control.c
>>> @@ -623,6 +623,7 @@ void __init omap3_ctrl_init(void)
>>> 
>>> struct control_init_data {
>>> 	int index;
>>> +	void __iomem *mem;
>>> 	s16 offset;
>>> };
>>> 
>>> @@ -635,6 +636,10 @@ static const struct control_init_data omap2_ctrl_data = {
>>> 	.offset = -OMAP2_CONTROL_GENERAL,
>>> };
>>> 
>>> +static const struct control_init_data ctrl_aux_data = {
>>> +	.index = TI_CLKM_CTRL_AUX,
>>> +};
>>> +
>>> static const struct of_device_id omap_scrm_dt_match_table[] = {
>>> 	{ .compatible = "ti,am3-scm", .data = &ctrl_data },
>>> 	{ .compatible = "ti,am4-scm", .data = &ctrl_data },
>>> @@ -644,6 +649,7 @@ static const struct of_device_id omap_scrm_dt_match_table[] = {
>>> 	{ .compatible = "ti,dm816-scrm", .data = &ctrl_data },
>>> 	{ .compatible = "ti,omap4-scm-core", .data = &ctrl_data },
>>> 	{ .compatible = "ti,omap5-scm-core", .data = &ctrl_data },
>>> +	{ .compatible = "ti,omap5-scm-wkup-pad-conf", .data = &ctrl_aux_data },
>>> 	{ .compatible = "ti,dra7-scm-core", .data = &ctrl_data },
>>> 	{ }
>>> };
>>> @@ -660,15 +666,21 @@ int __init omap2_control_base_init(void)
>>> 	struct device_node *np;
>>> 	const struct of_device_id *match;
>>> 	struct control_init_data *data;
>>> +	void __iomem *mem;
>>> 
>>> 	for_each_matching_node_and_match(np, omap_scrm_dt_match_table, &match) {
>>> 		data = (struct control_init_data *)match->data;
>>> 
>>> -		omap2_ctrl_base = of_iomap(np, 0);
>>> -		if (!omap2_ctrl_base)
>>> +		mem = of_iomap(np, 0);
>>> +		if (!mem)
>>> 			return -ENOMEM;
>>> 
>>> -		omap2_ctrl_offset = data->offset;
>>> +		if (data->index == TI_CLKM_CTRL) {
>>> +			omap2_ctrl_base = mem;
>>> +			omap2_ctrl_offset = data->offset;
>>> +		}
>>> +
>>> +		data->mem = mem;
>>> 	}
>>> 
>>> 	return 0;
>>> @@ -713,7 +725,7 @@ int __init omap_control_init(void)
>>> 		} else {
>>> 			/* No scm_conf found, direct access */
>>> 			ret = omap2_clk_provider_init(np, data->index, NULL,
>>> -						      omap2_ctrl_base);
>>> +						      data->mem);
>>> 			if (ret)
>>> 				return ret;
>>> 		}
>>> diff --git a/include/linux/clk/ti.h b/include/linux/clk/ti.h
>>> index dc5164a..be25aa8 100644
>>> --- a/include/linux/clk/ti.h
>>> +++ b/include/linux/clk/ti.h
>>> @@ -195,6 +195,7 @@ enum {
>>> 	TI_CLKM_PRM,
>>> 	TI_CLKM_SCRM,
>>> 	TI_CLKM_CTRL,
>>> +	TI_CLKM_CTRL_AUX,
>>> 	TI_CLKM_PLLSS,
>>> 	CLK_MAX_MEMMAPS
>>> };
>> 
> 

finally I found some time to apply your patches. Sorry for the long time.

Unfortunately, it does not work. Neither on omap5evm nor on our omap5 hardware.
I get no sound on the twl6040 - just white noise (which can be controlled in level through
amixer so it is created on the digital input side of the twl6040).

So I think your patch is missing a detail compared to my simple solution.

BR,
Nikolaus




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