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Date: Thu, 28 Apr 2016 11:03:32 +0300
From: Tero Kristo <t-kristo@...com>
To: "H. Nikolaus Schaller" <hns@...delico.com>,
Peter Ujfalusi <peter.ujfalusi@...com>
CC: Tony Lindgren <tony@...mide.com>,
Benoît Cousson <bcousson@...libre.com>,
Rob Herring <robh+dt@...nel.org>,
Pawel Moll <pawel.moll@....com>,
Mark Rutland <mark.rutland@....com>,
Ian Campbell <ijc+devicetree@...lion.org.uk>,
Kumar Gala <galak@...eaurora.org>,
Russell King <linux@....linux.org.uk>,
Laxman Dewangan <ldewangan@...dia.com>,
linux-omap <linux-omap@...r.kernel.org>,
<devicetree@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
Marek Belisko <marek@...delico.com>,
<kernel@...a-handheld.com>,
Discussions about the Letux Kernel
<letux-kernel@...nphoenux.org>
Subject: Re: [PATCH v2 4/5] ARM: dts: omap5: describe control for ckobuffer
On 27/04/16 17:35, H. Nikolaus Schaller wrote:
> HI,
>
>> Am 27.04.2016 um 16:23 schrieb Peter Ujfalusi <peter.ujfalusi@...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@...com>:
>>>>>
>>>>> On 27/04/16 09:04, H. Nikolaus Schaller wrote:
>>>>>>
>>>>>>> Am 26.04.2016 um 19:27 schrieb Tony Lindgren <tony@...mide.com>:
>>>>>>>
>>>>>>> Tero,
>>>>>>>
>>>>>>> * H. Nikolaus Schaller <hns@...delico.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.
From: Tero Kristo <t-kristo@...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@...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@...0 {
+ 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@0 {
+ compatible = "syscon", "simple-bus";
+ reg = <0x0 0x60>;
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges = <0 0x0 0x60>;
+
+ scm_wkup_pad_conf_clocks: clocks@0 {
+ #address-cells = <1>;
+ #size-cells = <0>;
+ };
+ };
+ };
};
ocmcram: ocmcram@...00000 {
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
};
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