Re: [PATCH 1/4] dt-bindings: firmware: imx-scu: new binding to parse clocks from device tree

Re: [PATCH 1/4] dt-bindings: firmware: imx-scu: new binding to parse clocks from device tree

[Aisheng Dong]

Hi Rob,

> > > > a/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > > > b/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > > > index 72d481c..2816789 100644
> > > > --- a/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > > > +++ b/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > > > @@ -78,6 +78,19 @@ Required properties:
> > > >                       "fsl,imx8qm-clock"
> > > >                       "fsl,imx8qxp-clock"
> > > >                     followed by "fsl,scu-clk"
> > > > +- #clock-cells:            Should be 0.
> > > > +- rsrc-id:         Resource ID associated with this clock
> > > > +- clk-type:                Type of this clock.
> > > > +                   Refer to <include/dt-bindings/firmware/imx/rsrc.h>
> for
> > > > +                   available clock types supported by SCU.
> > >
> > > Can't you just make these 2 values clock cells? I'm all for getting
> > > rid of made up clock numbers.
> > >
> >
> > Thanks for the agreement to remove clock IDs.
> >
> > The 2 values clock cell seems not the best approach for i.MX because
> > it still needs to define all clocks in the driver which is exactly we
> > want to avoid now due to some special HW characteristic:
> 
> Why's that? You can walk the DT and extract the 2 cells for each clock present.
> That's not any different than walking child nodes here and getting the resource
> ids and type. That's not really fast, but if speed is really an issue we can
> consider addressing that in ways that extend rather than change the binding.
> 

Due to searching the 'clocks' property of all device nodes indirectly to 
exact the 2 cell value causes much troubles in driver implementation and
looks a bit weird and is very low efficiency ( the performance will also potentially
be affected by adding new unrelevant nodes which is bad), we found the below
alternative way to do the same 2 cell binding, but having no performance issue.
It's much similar to the ARM SCPI clock binding.
Documentation/devicetree/bindings/arm/arm,scpi.txt

Do you think if it's okay to you?

If we have to use 2 cell binding, we probably would prefer to use this way
as it can relief us a lot from indirectly searching the 'clocks' property. 

If you're ok, please let me know, I will make it in V2 for the review.

enet0_clk: clock-enet0 {
        compatible = "fsl,imx8qxp-clock", "fsl,scu-clk";
        #clock-cells = <2>;
        clock-indice = <IMX_SC_PM_CLK_PER>,		// clock cell 2 value
                       <IMX_SC_PM_CLK_BYPASS>,
                       <IMX_SC_PM_CLK_MISC0>;
        clock-output-names = "enet0_clk",
                             "enet0_bypass_clk",
                             "enet0_rgmii_clk";
		// we can use the same resource id for clock cells 1 value
		// or probably encoded in node@reg?
        power-domains = <&pd IMX_SC_R_ENET_0>; 
};

enet0_lpcg: clock-controller@5b230000 {
        compatible = "fsl,imx8qxp-lpcg";
        reg = <0x5b230000 0x10000>;
        #clock-cells = <1>;
        clocks = <&enet0_clk IMX_SC_R_ENET_0 IMX_SC_PM_CLK_PER>,
                 <&enet0_clk IMX_SC_R_ENET_0 IMX_SC_PM_CLK_PER>,
                 <&conn_axi_clk>, <&conn_ipg_clk>, <&conn_ipg_clk>;
        bit-offset = <0 4 8 16 20>;
        clock-output-names = "enet0_ipg_root_clk",
                             "enet0_tx_clk",
                             "enet0_ahb_clk",
                             "enet0_ipg_clk",
                             "enet0_ipg_s_clk";
        power-domains = <&pd IMX_SC_R_ENET_0>;
};

fec1: ethernet@5b040000 {
        reg = <0x5b040000 0x10000>;
        interrupts = <GIC_SPI 258 IRQ_TYPE_LEVEL_HIGH>,
                     <GIC_SPI 256 IRQ_TYPE_LEVEL_HIGH>,
                     <GIC_SPI 257 IRQ_TYPE_LEVEL_HIGH>,
                     <GIC_SPI 259 IRQ_TYPE_LEVEL_HIGH>;
        clocks = <&enet0_lpcg 3>,
                 <&enet0_lpcg 2>,
                 <&enet0_lpcg 1>,
                 <&enet0_lpcg 0>;
        clock-names = "ipg", "ahb", "enet_clk_ref", "ptp";
        fsl,num-tx-queues=<3>;
        fsl,num-rx-queues=<3>;
        power-domains = <&pd IMX_SC_R_ENET_0>;
        status = "disabled";
};

Regards
Dong Aisheng

Re: [PATCH 1/4] dt-bindings: firmware: imx-scu: new binding to parse clocks from device tree

[Rob Herring]

On Wed, Mar 27, 2019 at 9:35 AM Aisheng Dong <aisheng.dong@nxp.com> wrote:
>
> > From: Rob Herring [mailto:robh@kernel.org]
> > Sent: Tuesday, March 26, 2019 9:47 PM
> > On Thu, Feb 21, 2019 at 06:03:43PM +0000, Aisheng Dong wrote:
> > > There's a few limitations on one cell clock binding (#clock-cells =
> > > <1>) that we have to define all clock IDs for device tree to reference.
> > > This may cause troubles if we want to use common clock IDs for multi
> > > platforms support when the clock of those platforms are mostly the same.
> > > e.g. Current clock IDs name are defined with SS prefix. However the
> > > device may reside in different SS across CPUs, that means the SS
> > > prefix may not valid anymore for a new SoC. Furthermore, the device
> > > availability of those clocks may also vary a bit.
> > >
> > > For such situation, We formerly planned to add all new IDs for each SS
> > > and dynamically check availability for different SoC in driver. That
> > > can be done but that may involve a lot effort and may result in more
> > > changes and duplicated code in driver, also make device tree
> > > upstreaming hard which depends on Clock IDs.
> > >
> > > To relief this situation, we want to move the clock definition into
> > > device tree which can fully decouple the dependency of Clock ID
> > > definition from device tree. And no frequent changes required in clock driver
> > any more.
> > >
> > > Then we can use the existence of clock nodes in device tree to address
> > > the device and clock availability differences across different SoCs.
> > >
> > > For SCU clocks, only two params required, thus two new property created:
> > > rsrc-id = <IMX_SC_R_UART_0>;
> > > clk-type = <IMX_SC_PM_CLK_PER>;
> > >
> > > And as we want to support clock set parent function, 'clocks' property
> > > is also used to pass all the possible input parents.
> > >
> > > Cc: Rob Herring <robh@kernel.org>
> > > Cc: Stephen Boyd <sboyd@kernel.org>
> > > Cc: Shawn Guo <shawnguo@kernel.org>
> > > Cc: Sascha Hauer <kernel@pengutronix.de>
> > > Cc: Michael Turquette <mturquette@baylibre.com>
> > > Cc: devicetree@vger.kernel.org
> > > Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
> > > ---
> > >  .../devicetree/bindings/arm/freescale/fsl,scu.txt  | 29
> > ++++++++++++++++------
> > >  include/dt-bindings/firmware/imx/rsrc.h            | 17
> > +++++++++++++
> > >  2 files changed, 38 insertions(+), 8 deletions(-)
> > >
> > > diff --git
> > > a/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > > b/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > > index 72d481c..2816789 100644
> > > --- a/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > > +++ b/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > > @@ -78,6 +78,19 @@ Required properties:
> > >                       "fsl,imx8qm-clock"
> > >                       "fsl,imx8qxp-clock"
> > >                     followed by "fsl,scu-clk"
> > > +- #clock-cells:            Should be 0.
> > > +- rsrc-id:         Resource ID associated with this clock
> > > +- clk-type:                Type of this clock.
> > > +                   Refer to <include/dt-bindings/firmware/imx/rsrc.h> for
> > > +                   available clock types supported by SCU.
> >
> > Can't you just make these 2 values clock cells? I'm all for getting rid of made
> > up clock numbers.
> >
>
> Thanks for the agreement to remove clock IDs.
>
> The 2 values clock cell seems not the best approach for i.MX because it still needs
> to define all clocks in the driver which is exactly we want to avoid now due to some
> special HW characteristic:

Why's that? You can walk the DT and extract the 2 cells for each clock
present. That's not any different than walking child nodes here and
getting the resource ids and type. That's not really fast, but if
speed is really an issue we can consider addressing that in ways that
extend rather than change the binding.

> 1. clock resources may be allocated to different SW execution partition by firmware
> and A core may not have access rights for those clocks not belong to its partition.
> So we want to describe them in DT according to the partition configuration.

Do you have an example? I'd assume you assign peripherals to different
partitions and resource assignment simply follows that. Can clocks not
be available when a peripheral still is?

> 2. Each clock is associated with a different power domain which is better to be
> described in device tree. And clock state will be lost and need restore after power cycle
> of the domain.
>
> Based on above requirements, do you think we can do as below?

Can you provide an example that shows the whole hierarchy for a
peripheral. Here you have FSPI, PWM, and MMC. Reviewing SCU clocks and
LPCG clocks separately is not helpful.

>
> //LSIO SS
> lsio_scu_clk: lsio-scu-clock-controller {
>         compatible = "fsl,imx8qxp-clock", "fsl,scu-clk";
>
>         fspi0_clk: clock-fspi0{
>                 #clock-cells = <0>;
>                 rsrc-id = <IMX_SC_R_FSPI_0>;
>                 clk-type = <IMX_SC_PM_CLK_PER>;
>                 power-domains = <&pd IMX_SC_R_FSPI_0>;

Are the power domain ID and rsrc-id always the same for a clock?

>         };
>
>                 fspi1_clk: clock-fspi1{
>                         ...
>                 };
>         ...
> };
>
> /* LPCG clocks */
> lsio_lpcg_clk: lsio-lpcg-clock-controller {
>         compatible = "fsl,imx8qxp-lpcg";

I think this wrapper node should be removed and the compatible moved
into the child nodes.

>         pwm0_lpcg: clock-controller@5d400000 {
>                 reg = <0x5d400000 0x10000>;
>                 #clock-cells = <1>;
>                 clocks = <&pwm0_clk>, <&pwm0_clk>, <&pwm0_clk>,
>                          <&lsio_bus_clk>, <&pwm0_clk>;
>                 bit-offset = <0 4 16 20 24>;

Are all LPCG instances the same, but some clocks are missing if the
child peripheral doesn't use certain clocks? IOW, bit 0 is always
ipg_clk, bit 24 is always ipg_mstr_clk?

Assuming so, 'bit-offset' should be removed and you should either have
a fixed number of clock entries with 0 entries for non-connected
clocks or use clock-names to define which clocks are present (with the
same set of defined names for all LPCG instances).

>                 clock-output-names = "pwm0_lpcg_ipg_clk",
>                                      "pwm0_lpcg_ipg_hf_clk",
>                                      "pwm0_lpcg_ipg_s_clk",
>                                      "pwm0_lpcg_ipg_slv_clk",
>                                      "pwm0_lpcg_ipg_mstr_clk";

IMO, this is wrong as the names should be relative to the module. So
'ipg_clk', 'ipg_hf_clk', etc.

>                 power-domains = <&pd IMX_SC_R_PWM_0>;
>                 status = "disabled";
>         };
>
>                 pwm1_lpcg: clock-controller@5d410000 {
>                                 ...
>                 }
>         ...
> };
>
> And for users, it could simply be:
> usdhc1: mmc@5b010000 {
>         clocks = <&sdhc0_lpcg 1>,
>                  <&sdhc0_lpcg 0>,
>                  <&sdhc0_lpcg 2>;
>         clock-names = "ipg", "per", "ahb";
>         assigned-clocks = <&sdhc0_clk>;
>         assigned-clock-rates = <200000000>;
>                 ....
> };

RE: [PATCH 1/4] dt-bindings: firmware: imx-scu: new binding to parse clocks from device tree

[Aisheng Dong]

Hi Rob,

Could you maybe shed a little light on this?

We're blocking here for the further work.

Regards
Dong Aisheng

> From: Aisheng Dong
> Sent: Tuesday, April 2, 2019 10:47 PM
> 
> Hi Rob,
> 
> > From: Aisheng Dong
> > Sent: Wednesday, March 27, 2019 10:35 PM
> > > From: Rob Herring [mailto:robh@kernel.org]
> > > Sent: Tuesday, March 26, 2019 9:47 PM On Thu, Feb 21, 2019 at
> > > 06:03:43PM +0000, Aisheng Dong wrote:
> > > > There's a few limitations on one cell clock binding (#clock-cells
> > > > =
> > > > <1>) that we have to define all clock IDs for device tree to reference.
> > > > This may cause troubles if we want to use common clock IDs for
> > > > multi platforms support when the clock of those platforms are mostly the
> same.
> > > > e.g. Current clock IDs name are defined with SS prefix. However
> > > > the device may reside in different SS across CPUs, that means the
> > > > SS prefix may not valid anymore for a new SoC. Furthermore, the
> > > > device availability of those clocks may also vary a bit.
> > > >
> > > > For such situation, We formerly planned to add all new IDs for
> > > > each SS and dynamically check availability for different SoC in driver.
> > > > That can be done but that may involve a lot effort and may result
> > > > in more changes and duplicated code in driver, also make device
> > > > tree upstreaming hard which depends on Clock IDs.
> > > >
> > > > To relief this situation, we want to move the clock definition
> > > > into device tree which can fully decouple the dependency of Clock
> > > > ID definition from device tree. And no frequent changes required
> > > > in clock driver
> > > any more.
> > > >
> > > > Then we can use the existence of clock nodes in device tree to
> > > > address the device and clock availability differences across different SoCs.
> > > >
> > > > For SCU clocks, only two params required, thus two new property
> created:
> > > > rsrc-id = <IMX_SC_R_UART_0>;
> > > > clk-type = <IMX_SC_PM_CLK_PER>;
> > > >
> > > > And as we want to support clock set parent function, 'clocks'
> > > > property is also used to pass all the possible input parents.
> > > >
> > > > Cc: Rob Herring <robh@kernel.org>
> > > > Cc: Stephen Boyd <sboyd@kernel.org>
> > > > Cc: Shawn Guo <shawnguo@kernel.org>
> > > > Cc: Sascha Hauer <kernel@pengutronix.de>
> > > > Cc: Michael Turquette <mturquette@baylibre.com>
> > > > Cc: devicetree@vger.kernel.org
> > > > Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
> > > > ---
> > > >  .../devicetree/bindings/arm/freescale/fsl,scu.txt  | 29
> > > ++++++++++++++++------
> > > >  include/dt-bindings/firmware/imx/rsrc.h            | 17
> > > +++++++++++++
> > > >  2 files changed, 38 insertions(+), 8 deletions(-)
> > > >
> > > > diff --git
> > > > a/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > > > b/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > > > index 72d481c..2816789 100644
> > > > --- a/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > > > +++ b/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > > > @@ -78,6 +78,19 @@ Required properties:
> > > >  			  "fsl,imx8qm-clock"
> > > >  			  "fsl,imx8qxp-clock"
> > > >  			followed by "fsl,scu-clk"
> > > > +- #clock-cells:		Should be 0.
> > > > +- rsrc-id:		Resource ID associated with this clock
> > > > +- clk-type:		Type of this clock.
> > > > +			Refer to <include/dt-bindings/firmware/imx/rsrc.h> for
> > > > +			available clock types supported by SCU.
> > >
> > > Can't you just make these 2 values clock cells? I'm all for getting
> > > rid of made up clock numbers.
> > >
> >
> > Thanks for the agreement to remove clock IDs.
> >
> > The 2 values clock cell seems not the best approach for i.MX because
> > it still needs to define all clocks in the driver which is exactly we
> > want to avoid now due to some special HW characteristic:
> > 1. clock resources may be allocated to different SW execution
> > partition by firmware and A core may not have access rights for those
> > clocks not belong to its partition.
> > So we want to describe them in DT according to the partition configuration.
> >
> > 2. Each clock is associated with a different power domain which is
> > better to be described in device tree. And clock state will be lost
> > and need restore after power cycle of the domain.
> >
> > Based on above requirements, do you think we can do as below?
> >
> 
> Would you help check if this is okay to you?
> 
> Regards
> Dong Aisheng
> 
> > //LSIO SS
> > lsio_scu_clk: lsio-scu-clock-controller {
> >         compatible = "fsl,imx8qxp-clock", "fsl,scu-clk";
> >
> >         fspi0_clk: clock-fspi0{
> >                 #clock-cells = <0>;
> >                 rsrc-id = <IMX_SC_R_FSPI_0>;
> >                 clk-type = <IMX_SC_PM_CLK_PER>;
> >                 power-domains = <&pd IMX_SC_R_FSPI_0>;
> >         };
> >
> > 		fspi1_clk: clock-fspi1{
> > 			...
> > 		};
> >         ...
> > };
> >
> > /* LPCG clocks */
> > lsio_lpcg_clk: lsio-lpcg-clock-controller {
> >         compatible = "fsl,imx8qxp-lpcg";
> >
> >         pwm0_lpcg: clock-controller@5d400000 {
> >                 reg = <0x5d400000 0x10000>;
> >                 #clock-cells = <1>;
> >                 clocks = <&pwm0_clk>, <&pwm0_clk>, <&pwm0_clk>,
> >                          <&lsio_bus_clk>, <&pwm0_clk>;
> >                 bit-offset = <0 4 16 20 24>;
> >                 clock-output-names = "pwm0_lpcg_ipg_clk",
> >                                      "pwm0_lpcg_ipg_hf_clk",
> >                                      "pwm0_lpcg_ipg_s_clk",
> >                                      "pwm0_lpcg_ipg_slv_clk",
> >                                      "pwm0_lpcg_ipg_mstr_clk";
> >                 power-domains = <&pd IMX_SC_R_PWM_0>;
> >                 status = "disabled";
> >         };
> >
> > 		pwm1_lpcg: clock-controller@5d410000 {
> > 				...
> > 		}
> >         ...
> > };
> >
> > And for users, it could simply be:
> > usdhc1: mmc@5b010000 {
> >         clocks = <&sdhc0_lpcg 1>,
> >                  <&sdhc0_lpcg 0>,
> >                  <&sdhc0_lpcg 2>;
> >         clock-names = "ipg", "per", "ahb";
> >         assigned-clocks = <&sdhc0_clk>;
> >         assigned-clock-rates = <200000000>;
> > 		....
> > };
> >
> > Regards
> > Dong Aisheng
> >
> > > > +- clock-output-names:	Shall be the corresponding names of the outputs.
> > > > +
> > > > +Optional properties:
> > > > +- clocks:		Shall be the input parent clock(s) phandle for the clock.
> > > > +			For multiplexed clocks, the list order must match the
> hardware
> > > > +			programming order.
> > > > +
> > > > +Legacy Clock binding (DEPRECATED):
> > > >  - #clock-cells:		Should be 1. Contains the Clock ID value.
> > > >  - clocks:		List of clock specifiers, must contain an entry for
> > > >  			each required entry in clock-names @@ -129,6 +142,13
> > @@
> > > lsio_mu1:
> > > > mailbox@5d1c0000 {
> > > >  	#mbox-cells = <2>;
> > > >  };
> > > >
> > > > +uart0_clk: uart0-clock-controller {
> > > > +	compatible = "fsl,imx8qxp-scu-pd", "fsl,scu-clk";
> > > > +	#clock-cells = <0>;
> > > > +	rsrc-id = <IMX_SC_R_UART_0>;
> > > > +	clk-type = <IMX_SC_PM_CLK_PER>;
> > > > +};
> > > > +
> > > >  firmware {
> > > >  	scu {
> > > >  		compatible = "fsl,imx-scu";
> > > > @@ -143,11 +163,6 @@ firmware {
> > > >  			  &lsio_mu1 1 2
> > > >  			  &lsio_mu1 1 3>;
> > > >
> > > > -		clk: clk {
> > > > -			compatible = "fsl,imx8qxp-clk", "fsl,scu-clk";
> > > > -			#clock-cells = <1>;
> > > > -		};
> > > > -
> > > >  		iomuxc {
> > > >  			compatible = "fsl,imx8qxp-iomuxc";
> > > >
> > > > @@ -175,8 +190,6 @@ serial@5a060000 {
> > > >  	...
> > > >  	pinctrl-names = "default";
> > > >  	pinctrl-0 = <&pinctrl_lpuart0>;
> > > > -	clocks = <&clk IMX8QXP_UART0_CLK>,
> > > > -		 <&clk IMX8QXP_UART0_IPG_CLK>;
> > > > -	clock-names = "per", "ipg";
> > > > +	clocks = <&uart0_clk>;
> > > >  	power-domains = <&pd IMX_SC_R_UART_0>;  }; diff --git
> > > > a/include/dt-bindings/firmware/imx/rsrc.h
> > > > b/include/dt-bindings/firmware/imx/rsrc.h
> > > > index 4481f2d..f650fc3 100644
> > > > --- a/include/dt-bindings/firmware/imx/rsrc.h
> > > > +++ b/include/dt-bindings/firmware/imx/rsrc.h
> > > > @@ -556,4 +556,21 @@
> > > >  #define IMX_SC_R_VPU			540
> > > >  #define IMX_SC_R_LAST			541
> > > >
> > > > +/*
> > > > + * Defines for SC PM CLK
> > > > + */
> > > > +#define IMX_SC_PM_CLK_SLV_BUS		0	/* Slave bus clock */
> > > > +#define IMX_SC_PM_CLK_MST_BUS		1	/* Master bus clock */
> > > > +#define IMX_SC_PM_CLK_PER		2	/* Peripheral clock */
> > > > +#define IMX_SC_PM_CLK_PHY		3	/* Phy clock */
> > > > +#define IMX_SC_PM_CLK_MISC		4	/* Misc clock */
> > > > +#define IMX_SC_PM_CLK_MISC0		0	/* Misc 0 clock */
> > > > +#define IMX_SC_PM_CLK_MISC1		1	/* Misc 1 clock */
> > > > +#define IMX_SC_PM_CLK_MISC2		2	/* Misc 2 clock */
> > > > +#define IMX_SC_PM_CLK_MISC3		3	/* Misc 3 clock */
> > > > +#define IMX_SC_PM_CLK_MISC4		4	/* Misc 4 clock */
> > > > +#define IMX_SC_PM_CLK_CPU		2	/* CPU clock */
> > > > +#define IMX_SC_PM_CLK_PLL		4	/* PLL */
> > > > +#define IMX_SC_PM_CLK_BYPASS		4	/* Bypass clock */
> > > > +
> > > >  #endif /* __DT_BINDINGS_RSCRC_IMX_H */
> > > > --
> > > > 2.7.4
> > > >

RE: [PATCH 1/4] dt-bindings: firmware: imx-scu: new binding to parse clocks from device tree

[Aisheng Dong]

Hi Rob,

> From: Aisheng Dong
> Sent: Wednesday, March 27, 2019 10:35 PM
> > From: Rob Herring [mailto:robh@kernel.org]
> > Sent: Tuesday, March 26, 2019 9:47 PM
> > On Thu, Feb 21, 2019 at 06:03:43PM +0000, Aisheng Dong wrote:
> > > There's a few limitations on one cell clock binding (#clock-cells =
> > > <1>) that we have to define all clock IDs for device tree to reference.
> > > This may cause troubles if we want to use common clock IDs for multi
> > > platforms support when the clock of those platforms are mostly the same.
> > > e.g. Current clock IDs name are defined with SS prefix. However the
> > > device may reside in different SS across CPUs, that means the SS
> > > prefix may not valid anymore for a new SoC. Furthermore, the device
> > > availability of those clocks may also vary a bit.
> > >
> > > For such situation, We formerly planned to add all new IDs for each
> > > SS and dynamically check availability for different SoC in driver.
> > > That can be done but that may involve a lot effort and may result in
> > > more changes and duplicated code in driver, also make device tree
> > > upstreaming hard which depends on Clock IDs.
> > >
> > > To relief this situation, we want to move the clock definition into
> > > device tree which can fully decouple the dependency of Clock ID
> > > definition from device tree. And no frequent changes required in
> > > clock driver
> > any more.
> > >
> > > Then we can use the existence of clock nodes in device tree to
> > > address the device and clock availability differences across different SoCs.
> > >
> > > For SCU clocks, only two params required, thus two new property created:
> > > rsrc-id = <IMX_SC_R_UART_0>;
> > > clk-type = <IMX_SC_PM_CLK_PER>;
> > >
> > > And as we want to support clock set parent function, 'clocks'
> > > property is also used to pass all the possible input parents.
> > >
> > > Cc: Rob Herring <robh@kernel.org>
> > > Cc: Stephen Boyd <sboyd@kernel.org>
> > > Cc: Shawn Guo <shawnguo@kernel.org>
> > > Cc: Sascha Hauer <kernel@pengutronix.de>
> > > Cc: Michael Turquette <mturquette@baylibre.com>
> > > Cc: devicetree@vger.kernel.org
> > > Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
> > > ---
> > >  .../devicetree/bindings/arm/freescale/fsl,scu.txt  | 29
> > ++++++++++++++++------
> > >  include/dt-bindings/firmware/imx/rsrc.h            | 17
> > +++++++++++++
> > >  2 files changed, 38 insertions(+), 8 deletions(-)
> > >
> > > diff --git
> > > a/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > > b/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > > index 72d481c..2816789 100644
> > > --- a/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > > +++ b/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > > @@ -78,6 +78,19 @@ Required properties:
> > >  			  "fsl,imx8qm-clock"
> > >  			  "fsl,imx8qxp-clock"
> > >  			followed by "fsl,scu-clk"
> > > +- #clock-cells:		Should be 0.
> > > +- rsrc-id:		Resource ID associated with this clock
> > > +- clk-type:		Type of this clock.
> > > +			Refer to <include/dt-bindings/firmware/imx/rsrc.h> for
> > > +			available clock types supported by SCU.
> >
> > Can't you just make these 2 values clock cells? I'm all for getting
> > rid of made up clock numbers.
> >
> 
> Thanks for the agreement to remove clock IDs.
> 
> The 2 values clock cell seems not the best approach for i.MX because it still
> needs to define all clocks in the driver which is exactly we want to avoid now
> due to some special HW characteristic:
> 1. clock resources may be allocated to different SW execution partition by
> firmware and A core may not have access rights for those clocks not belong to
> its partition.
> So we want to describe them in DT according to the partition configuration.
> 
> 2. Each clock is associated with a different power domain which is better to be
> described in device tree. And clock state will be lost and need restore after
> power cycle of the domain.
> 
> Based on above requirements, do you think we can do as below?
> 

Would you help check if this is okay to you?

Regards
Dong Aisheng

> //LSIO SS
> lsio_scu_clk: lsio-scu-clock-controller {
>         compatible = "fsl,imx8qxp-clock", "fsl,scu-clk";
> 
>         fspi0_clk: clock-fspi0{
>                 #clock-cells = <0>;
>                 rsrc-id = <IMX_SC_R_FSPI_0>;
>                 clk-type = <IMX_SC_PM_CLK_PER>;
>                 power-domains = <&pd IMX_SC_R_FSPI_0>;
>         };
> 
> 		fspi1_clk: clock-fspi1{
> 			...
> 		};
>         ...
> };
> 
> /* LPCG clocks */
> lsio_lpcg_clk: lsio-lpcg-clock-controller {
>         compatible = "fsl,imx8qxp-lpcg";
> 
>         pwm0_lpcg: clock-controller@5d400000 {
>                 reg = <0x5d400000 0x10000>;
>                 #clock-cells = <1>;
>                 clocks = <&pwm0_clk>, <&pwm0_clk>, <&pwm0_clk>,
>                          <&lsio_bus_clk>, <&pwm0_clk>;
>                 bit-offset = <0 4 16 20 24>;
>                 clock-output-names = "pwm0_lpcg_ipg_clk",
>                                      "pwm0_lpcg_ipg_hf_clk",
>                                      "pwm0_lpcg_ipg_s_clk",
>                                      "pwm0_lpcg_ipg_slv_clk",
>                                      "pwm0_lpcg_ipg_mstr_clk";
>                 power-domains = <&pd IMX_SC_R_PWM_0>;
>                 status = "disabled";
>         };
> 
> 		pwm1_lpcg: clock-controller@5d410000 {
> 				...
> 		}
>         ...
> };
> 
> And for users, it could simply be:
> usdhc1: mmc@5b010000 {
>         clocks = <&sdhc0_lpcg 1>,
>                  <&sdhc0_lpcg 0>,
>                  <&sdhc0_lpcg 2>;
>         clock-names = "ipg", "per", "ahb";
>         assigned-clocks = <&sdhc0_clk>;
>         assigned-clock-rates = <200000000>;
> 		....
> };
> 
> Regards
> Dong Aisheng
> 
> > > +- clock-output-names:	Shall be the corresponding names of the outputs.
> > > +
> > > +Optional properties:
> > > +- clocks:		Shall be the input parent clock(s) phandle for the clock.
> > > +			For multiplexed clocks, the list order must match the hardware
> > > +			programming order.
> > > +
> > > +Legacy Clock binding (DEPRECATED):
> > >  - #clock-cells:		Should be 1. Contains the Clock ID value.
> > >  - clocks:		List of clock specifiers, must contain an entry for
> > >  			each required entry in clock-names @@ -129,6 +142,13
> @@
> > lsio_mu1:
> > > mailbox@5d1c0000 {
> > >  	#mbox-cells = <2>;
> > >  };
> > >
> > > +uart0_clk: uart0-clock-controller {
> > > +	compatible = "fsl,imx8qxp-scu-pd", "fsl,scu-clk";
> > > +	#clock-cells = <0>;
> > > +	rsrc-id = <IMX_SC_R_UART_0>;
> > > +	clk-type = <IMX_SC_PM_CLK_PER>;
> > > +};
> > > +
> > >  firmware {
> > >  	scu {
> > >  		compatible = "fsl,imx-scu";
> > > @@ -143,11 +163,6 @@ firmware {
> > >  			  &lsio_mu1 1 2
> > >  			  &lsio_mu1 1 3>;
> > >
> > > -		clk: clk {
> > > -			compatible = "fsl,imx8qxp-clk", "fsl,scu-clk";
> > > -			#clock-cells = <1>;
> > > -		};
> > > -
> > >  		iomuxc {
> > >  			compatible = "fsl,imx8qxp-iomuxc";
> > >
> > > @@ -175,8 +190,6 @@ serial@5a060000 {
> > >  	...
> > >  	pinctrl-names = "default";
> > >  	pinctrl-0 = <&pinctrl_lpuart0>;
> > > -	clocks = <&clk IMX8QXP_UART0_CLK>,
> > > -		 <&clk IMX8QXP_UART0_IPG_CLK>;
> > > -	clock-names = "per", "ipg";
> > > +	clocks = <&uart0_clk>;
> > >  	power-domains = <&pd IMX_SC_R_UART_0>;  }; diff --git
> > > a/include/dt-bindings/firmware/imx/rsrc.h
> > > b/include/dt-bindings/firmware/imx/rsrc.h
> > > index 4481f2d..f650fc3 100644
> > > --- a/include/dt-bindings/firmware/imx/rsrc.h
> > > +++ b/include/dt-bindings/firmware/imx/rsrc.h
> > > @@ -556,4 +556,21 @@
> > >  #define IMX_SC_R_VPU			540
> > >  #define IMX_SC_R_LAST			541
> > >
> > > +/*
> > > + * Defines for SC PM CLK
> > > + */
> > > +#define IMX_SC_PM_CLK_SLV_BUS		0	/* Slave bus clock */
> > > +#define IMX_SC_PM_CLK_MST_BUS		1	/* Master bus clock */
> > > +#define IMX_SC_PM_CLK_PER		2	/* Peripheral clock */
> > > +#define IMX_SC_PM_CLK_PHY		3	/* Phy clock */
> > > +#define IMX_SC_PM_CLK_MISC		4	/* Misc clock */
> > > +#define IMX_SC_PM_CLK_MISC0		0	/* Misc 0 clock */
> > > +#define IMX_SC_PM_CLK_MISC1		1	/* Misc 1 clock */
> > > +#define IMX_SC_PM_CLK_MISC2		2	/* Misc 2 clock */
> > > +#define IMX_SC_PM_CLK_MISC3		3	/* Misc 3 clock */
> > > +#define IMX_SC_PM_CLK_MISC4		4	/* Misc 4 clock */
> > > +#define IMX_SC_PM_CLK_CPU		2	/* CPU clock */
> > > +#define IMX_SC_PM_CLK_PLL		4	/* PLL */
> > > +#define IMX_SC_PM_CLK_BYPASS		4	/* Bypass clock */
> > > +
> > >  #endif /* __DT_BINDINGS_RSCRC_IMX_H */
> > > --
> > > 2.7.4
> > >

RE: [PATCH 1/4] dt-bindings: firmware: imx-scu: new binding to parse clocks from device tree

[Aisheng Dong]

> From: Rob Herring [mailto:robh@kernel.org]
> Sent: Tuesday, March 26, 2019 9:47 PM
> On Thu, Feb 21, 2019 at 06:03:43PM +0000, Aisheng Dong wrote:
> > There's a few limitations on one cell clock binding (#clock-cells =
> > <1>) that we have to define all clock IDs for device tree to reference.
> > This may cause troubles if we want to use common clock IDs for multi
> > platforms support when the clock of those platforms are mostly the same.
> > e.g. Current clock IDs name are defined with SS prefix. However the
> > device may reside in different SS across CPUs, that means the SS
> > prefix may not valid anymore for a new SoC. Furthermore, the device
> > availability of those clocks may also vary a bit.
> >
> > For such situation, We formerly planned to add all new IDs for each SS
> > and dynamically check availability for different SoC in driver. That
> > can be done but that may involve a lot effort and may result in more
> > changes and duplicated code in driver, also make device tree
> > upstreaming hard which depends on Clock IDs.
> >
> > To relief this situation, we want to move the clock definition into
> > device tree which can fully decouple the dependency of Clock ID
> > definition from device tree. And no frequent changes required in clock driver
> any more.
> >
> > Then we can use the existence of clock nodes in device tree to address
> > the device and clock availability differences across different SoCs.
> >
> > For SCU clocks, only two params required, thus two new property created:
> > rsrc-id = <IMX_SC_R_UART_0>;
> > clk-type = <IMX_SC_PM_CLK_PER>;
> >
> > And as we want to support clock set parent function, 'clocks' property
> > is also used to pass all the possible input parents.
> >
> > Cc: Rob Herring <robh@kernel.org>
> > Cc: Stephen Boyd <sboyd@kernel.org>
> > Cc: Shawn Guo <shawnguo@kernel.org>
> > Cc: Sascha Hauer <kernel@pengutronix.de>
> > Cc: Michael Turquette <mturquette@baylibre.com>
> > Cc: devicetree@vger.kernel.org
> > Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
> > ---
> >  .../devicetree/bindings/arm/freescale/fsl,scu.txt  | 29
> ++++++++++++++++------
> >  include/dt-bindings/firmware/imx/rsrc.h            | 17
> +++++++++++++
> >  2 files changed, 38 insertions(+), 8 deletions(-)
> >
> > diff --git
> > a/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > b/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > index 72d481c..2816789 100644
> > --- a/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > +++ b/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> > @@ -78,6 +78,19 @@ Required properties:
> >  			  "fsl,imx8qm-clock"
> >  			  "fsl,imx8qxp-clock"
> >  			followed by "fsl,scu-clk"
> > +- #clock-cells:		Should be 0.
> > +- rsrc-id:		Resource ID associated with this clock
> > +- clk-type:		Type of this clock.
> > +			Refer to <include/dt-bindings/firmware/imx/rsrc.h> for
> > +			available clock types supported by SCU.
> 
> Can't you just make these 2 values clock cells? I'm all for getting rid of made
> up clock numbers.
> 

Thanks for the agreement to remove clock IDs.

The 2 values clock cell seems not the best approach for i.MX because it still needs
to define all clocks in the driver which is exactly we want to avoid now due to some
special HW characteristic:
1. clock resources may be allocated to different SW execution partition by firmware
and A core may not have access rights for those clocks not belong to its partition.
So we want to describe them in DT according to the partition configuration.

2. Each clock is associated with a different power domain which is better to be
described in device tree. And clock state will be lost and need restore after power cycle
of the domain.

Based on above requirements, do you think we can do as below?

//LSIO SS
lsio_scu_clk: lsio-scu-clock-controller {
        compatible = "fsl,imx8qxp-clock", "fsl,scu-clk";

        fspi0_clk: clock-fspi0{
                #clock-cells = <0>;
                rsrc-id = <IMX_SC_R_FSPI_0>;
                clk-type = <IMX_SC_PM_CLK_PER>;
                power-domains = <&pd IMX_SC_R_FSPI_0>;
        };
		
		fspi1_clk: clock-fspi1{
			...
		};
        ...
};    

/* LPCG clocks */
lsio_lpcg_clk: lsio-lpcg-clock-controller {
        compatible = "fsl,imx8qxp-lpcg";

        pwm0_lpcg: clock-controller@5d400000 {
                reg = <0x5d400000 0x10000>;
                #clock-cells = <1>;
                clocks = <&pwm0_clk>, <&pwm0_clk>, <&pwm0_clk>,
                         <&lsio_bus_clk>, <&pwm0_clk>;
                bit-offset = <0 4 16 20 24>;
                clock-output-names = "pwm0_lpcg_ipg_clk",
                                     "pwm0_lpcg_ipg_hf_clk",
                                     "pwm0_lpcg_ipg_s_clk",
                                     "pwm0_lpcg_ipg_slv_clk",
                                     "pwm0_lpcg_ipg_mstr_clk";
                power-domains = <&pd IMX_SC_R_PWM_0>;
                status = "disabled";
        };

		pwm1_lpcg: clock-controller@5d410000 {
				...
		}
        ...
};

And for users, it could simply be:
usdhc1: mmc@5b010000 {
        clocks = <&sdhc0_lpcg 1>,
                 <&sdhc0_lpcg 0>,
                 <&sdhc0_lpcg 2>;
        clock-names = "ipg", "per", "ahb";
        assigned-clocks = <&sdhc0_clk>;
        assigned-clock-rates = <200000000>;
		....
};

Regards
Dong Aisheng

> > +- clock-output-names:	Shall be the corresponding names of the outputs.
> > +
> > +Optional properties:
> > +- clocks:		Shall be the input parent clock(s) phandle for the clock.
> > +			For multiplexed clocks, the list order must match the hardware
> > +			programming order.
> > +
> > +Legacy Clock binding (DEPRECATED):
> >  - #clock-cells:		Should be 1. Contains the Clock ID value.
> >  - clocks:		List of clock specifiers, must contain an entry for
> >  			each required entry in clock-names @@ -129,6 +142,13 @@
> lsio_mu1:
> > mailbox@5d1c0000 {
> >  	#mbox-cells = <2>;
> >  };
> >
> > +uart0_clk: uart0-clock-controller {
> > +	compatible = "fsl,imx8qxp-scu-pd", "fsl,scu-clk";
> > +	#clock-cells = <0>;
> > +	rsrc-id = <IMX_SC_R_UART_0>;
> > +	clk-type = <IMX_SC_PM_CLK_PER>;
> > +};
> > +
> >  firmware {
> >  	scu {
> >  		compatible = "fsl,imx-scu";
> > @@ -143,11 +163,6 @@ firmware {
> >  			  &lsio_mu1 1 2
> >  			  &lsio_mu1 1 3>;
> >
> > -		clk: clk {
> > -			compatible = "fsl,imx8qxp-clk", "fsl,scu-clk";
> > -			#clock-cells = <1>;
> > -		};
> > -
> >  		iomuxc {
> >  			compatible = "fsl,imx8qxp-iomuxc";
> >
> > @@ -175,8 +190,6 @@ serial@5a060000 {
> >  	...
> >  	pinctrl-names = "default";
> >  	pinctrl-0 = <&pinctrl_lpuart0>;
> > -	clocks = <&clk IMX8QXP_UART0_CLK>,
> > -		 <&clk IMX8QXP_UART0_IPG_CLK>;
> > -	clock-names = "per", "ipg";
> > +	clocks = <&uart0_clk>;
> >  	power-domains = <&pd IMX_SC_R_UART_0>;  }; diff --git
> > a/include/dt-bindings/firmware/imx/rsrc.h
> > b/include/dt-bindings/firmware/imx/rsrc.h
> > index 4481f2d..f650fc3 100644
> > --- a/include/dt-bindings/firmware/imx/rsrc.h
> > +++ b/include/dt-bindings/firmware/imx/rsrc.h
> > @@ -556,4 +556,21 @@
> >  #define IMX_SC_R_VPU			540
> >  #define IMX_SC_R_LAST			541
> >
> > +/*
> > + * Defines for SC PM CLK
> > + */
> > +#define IMX_SC_PM_CLK_SLV_BUS		0	/* Slave bus clock */
> > +#define IMX_SC_PM_CLK_MST_BUS		1	/* Master bus clock */
> > +#define IMX_SC_PM_CLK_PER		2	/* Peripheral clock */
> > +#define IMX_SC_PM_CLK_PHY		3	/* Phy clock */
> > +#define IMX_SC_PM_CLK_MISC		4	/* Misc clock */
> > +#define IMX_SC_PM_CLK_MISC0		0	/* Misc 0 clock */
> > +#define IMX_SC_PM_CLK_MISC1		1	/* Misc 1 clock */
> > +#define IMX_SC_PM_CLK_MISC2		2	/* Misc 2 clock */
> > +#define IMX_SC_PM_CLK_MISC3		3	/* Misc 3 clock */
> > +#define IMX_SC_PM_CLK_MISC4		4	/* Misc 4 clock */
> > +#define IMX_SC_PM_CLK_CPU		2	/* CPU clock */
> > +#define IMX_SC_PM_CLK_PLL		4	/* PLL */
> > +#define IMX_SC_PM_CLK_BYPASS		4	/* Bypass clock */
> > +
> >  #endif /* __DT_BINDINGS_RSCRC_IMX_H */
> > --
> > 2.7.4
> >

Re: [PATCH 1/4] dt-bindings: firmware: imx-scu: new binding to parse clocks from device tree

[Rob Herring]

On Thu, Feb 21, 2019 at 06:03:43PM +0000, Aisheng Dong wrote:
> There's a few limitations on one cell clock binding (#clock-cells = <1>)
> that we have to define all clock IDs for device tree to reference.
> This may cause troubles if we want to use common clock IDs for multi
> platforms support when the clock of those platforms are mostly the same.
> e.g. Current clock IDs name are defined with SS prefix. However the device
> may reside in different SS across CPUs, that means the SS prefix may
> not valid anymore for a new SoC. Furthermore, the device availability of
> those clocks may also vary a bit.
> 
> For such situation, We formerly planned to add all new IDs for each SS
> and dynamically check availability for different SoC in driver. That can
> be done but that may involve a lot effort and may result in more changes
> and duplicated code in driver, also make device tree upstreaming hard which
> depends on Clock IDs.
> 
> To relief this situation, we want to move the clock definition into
> device tree which can fully decouple the dependency of Clock ID definition
> from device tree. And no frequent changes required in clock driver any more.
> 
> Then we can use the existence of clock nodes in device tree to address the
> device and clock availability differences across different SoCs.
> 
> For SCU clocks, only two params required, thus two new property created:
> rsrc-id = <IMX_SC_R_UART_0>;
> clk-type = <IMX_SC_PM_CLK_PER>;
> 
> And as we want to support clock set parent function, 'clocks' property
> is also used to pass all the possible input parents.
> 
> Cc: Rob Herring <robh@kernel.org>
> Cc: Stephen Boyd <sboyd@kernel.org>
> Cc: Shawn Guo <shawnguo@kernel.org>
> Cc: Sascha Hauer <kernel@pengutronix.de>
> Cc: Michael Turquette <mturquette@baylibre.com>
> Cc: devicetree@vger.kernel.org
> Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
> ---
>  .../devicetree/bindings/arm/freescale/fsl,scu.txt  | 29 ++++++++++++++++------
>  include/dt-bindings/firmware/imx/rsrc.h            | 17 +++++++++++++
>  2 files changed, 38 insertions(+), 8 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt b/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> index 72d481c..2816789 100644
> --- a/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> +++ b/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> @@ -78,6 +78,19 @@ Required properties:
>  			  "fsl,imx8qm-clock"
>  			  "fsl,imx8qxp-clock"
>  			followed by "fsl,scu-clk"
> +- #clock-cells:		Should be 0.
> +- rsrc-id:		Resource ID associated with this clock
> +- clk-type:		Type of this clock.
> +			Refer to <include/dt-bindings/firmware/imx/rsrc.h> for
> +			available clock types supported by SCU.

Can't you just make these 2 values clock cells? I'm all for getting rid 
of made up clock numbers.

> +- clock-output-names:	Shall be the corresponding names of the outputs.
> +
> +Optional properties:
> +- clocks:		Shall be the input parent clock(s) phandle for the clock.
> +			For multiplexed clocks, the list order must match the hardware
> +			programming order.
> +
> +Legacy Clock binding (DEPRECATED):
>  - #clock-cells:		Should be 1. Contains the Clock ID value.
>  - clocks:		List of clock specifiers, must contain an entry for
>  			each required entry in clock-names
> @@ -129,6 +142,13 @@ lsio_mu1: mailbox@5d1c0000 {
>  	#mbox-cells = <2>;
>  };
>  
> +uart0_clk: uart0-clock-controller {
> +	compatible = "fsl,imx8qxp-scu-pd", "fsl,scu-clk";
> +	#clock-cells = <0>;
> +	rsrc-id = <IMX_SC_R_UART_0>;
> +	clk-type = <IMX_SC_PM_CLK_PER>;
> +};
> +
>  firmware {
>  	scu {
>  		compatible = "fsl,imx-scu";
> @@ -143,11 +163,6 @@ firmware {
>  			  &lsio_mu1 1 2
>  			  &lsio_mu1 1 3>;
>  
> -		clk: clk {
> -			compatible = "fsl,imx8qxp-clk", "fsl,scu-clk";
> -			#clock-cells = <1>;
> -		};
> -
>  		iomuxc {
>  			compatible = "fsl,imx8qxp-iomuxc";
>  
> @@ -175,8 +190,6 @@ serial@5a060000 {
>  	...
>  	pinctrl-names = "default";
>  	pinctrl-0 = <&pinctrl_lpuart0>;
> -	clocks = <&clk IMX8QXP_UART0_CLK>,
> -		 <&clk IMX8QXP_UART0_IPG_CLK>;
> -	clock-names = "per", "ipg";
> +	clocks = <&uart0_clk>;
>  	power-domains = <&pd IMX_SC_R_UART_0>;
>  };
> diff --git a/include/dt-bindings/firmware/imx/rsrc.h b/include/dt-bindings/firmware/imx/rsrc.h
> index 4481f2d..f650fc3 100644
> --- a/include/dt-bindings/firmware/imx/rsrc.h
> +++ b/include/dt-bindings/firmware/imx/rsrc.h
> @@ -556,4 +556,21 @@
>  #define IMX_SC_R_VPU			540
>  #define IMX_SC_R_LAST			541
>  
> +/*
> + * Defines for SC PM CLK
> + */
> +#define IMX_SC_PM_CLK_SLV_BUS		0	/* Slave bus clock */
> +#define IMX_SC_PM_CLK_MST_BUS		1	/* Master bus clock */
> +#define IMX_SC_PM_CLK_PER		2	/* Peripheral clock */
> +#define IMX_SC_PM_CLK_PHY		3	/* Phy clock */
> +#define IMX_SC_PM_CLK_MISC		4	/* Misc clock */
> +#define IMX_SC_PM_CLK_MISC0		0	/* Misc 0 clock */
> +#define IMX_SC_PM_CLK_MISC1		1	/* Misc 1 clock */
> +#define IMX_SC_PM_CLK_MISC2		2	/* Misc 2 clock */
> +#define IMX_SC_PM_CLK_MISC3		3	/* Misc 3 clock */
> +#define IMX_SC_PM_CLK_MISC4		4	/* Misc 4 clock */
> +#define IMX_SC_PM_CLK_CPU		2	/* CPU clock */
> +#define IMX_SC_PM_CLK_PLL		4	/* PLL */
> +#define IMX_SC_PM_CLK_BYPASS		4	/* Bypass clock */
> +
>  #endif /* __DT_BINDINGS_RSCRC_IMX_H */
> -- 
> 2.7.4
> 

[PATCH 1/4] dt-bindings: firmware: imx-scu: new binding to parse clocks from device tree

[Aisheng Dong]

There's a few limitations on one cell clock binding (#clock-cells = <1>)
that we have to define all clock IDs for device tree to reference.
This may cause troubles if we want to use common clock IDs for multi
platforms support when the clock of those platforms are mostly the same.
e.g. Current clock IDs name are defined with SS prefix. However the device
may reside in different SS across CPUs, that means the SS prefix may
not valid anymore for a new SoC. Furthermore, the device availability of
those clocks may also vary a bit.

For such situation, We formerly planned to add all new IDs for each SS
and dynamically check availability for different SoC in driver. That can
be done but that may involve a lot effort and may result in more changes
and duplicated code in driver, also make device tree upstreaming hard which
depends on Clock IDs.

To relief this situation, we want to move the clock definition into
device tree which can fully decouple the dependency of Clock ID definition
from device tree. And no frequent changes required in clock driver any more.

Then we can use the existence of clock nodes in device tree to address the
device and clock availability differences across different SoCs.

For SCU clocks, only two params required, thus two new property created:
rsrc-id = <IMX_SC_R_UART_0>;
clk-type = <IMX_SC_PM_CLK_PER>;

And as we want to support clock set parent function, 'clocks' property
is also used to pass all the possible input parents.

Cc: Rob Herring <robh@kernel.org>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: devicetree@vger.kernel.org
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
---
 .../devicetree/bindings/arm/freescale/fsl,scu.txt  | 29 ++++++++++++++++------
 include/dt-bindings/firmware/imx/rsrc.h            | 17 +++++++++++++
 2 files changed, 38 insertions(+), 8 deletions(-)

diff --git a/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt b/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
index 72d481c..2816789 100644
--- a/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
+++ b/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
@@ -78,6 +78,19 @@ Required properties:
 			  "fsl,imx8qm-clock"
 			  "fsl,imx8qxp-clock"
 			followed by "fsl,scu-clk"
+- #clock-cells:		Should be 0.
+- rsrc-id:		Resource ID associated with this clock
+- clk-type:		Type of this clock.
+			Refer to <include/dt-bindings/firmware/imx/rsrc.h> for
+			available clock types supported by SCU.
+- clock-output-names:	Shall be the corresponding names of the outputs.
+
+Optional properties:
+- clocks:		Shall be the input parent clock(s) phandle for the clock.
+			For multiplexed clocks, the list order must match the hardware
+			programming order.
+
+Legacy Clock binding (DEPRECATED):
 - #clock-cells:		Should be 1. Contains the Clock ID value.
 - clocks:		List of clock specifiers, must contain an entry for
 			each required entry in clock-names
@@ -129,6 +142,13 @@ lsio_mu1: mailbox@5d1c0000 {
 	#mbox-cells = <2>;
 };
 
+uart0_clk: uart0-clock-controller {
+	compatible = "fsl,imx8qxp-scu-pd", "fsl,scu-clk";
+	#clock-cells = <0>;
+	rsrc-id = <IMX_SC_R_UART_0>;
+	clk-type = <IMX_SC_PM_CLK_PER>;
+};
+
 firmware {
 	scu {
 		compatible = "fsl,imx-scu";
@@ -143,11 +163,6 @@ firmware {
 			  &lsio_mu1 1 2
 			  &lsio_mu1 1 3>;
 
-		clk: clk {
-			compatible = "fsl,imx8qxp-clk", "fsl,scu-clk";
-			#clock-cells = <1>;
-		};
-
 		iomuxc {
 			compatible = "fsl,imx8qxp-iomuxc";
 
@@ -175,8 +190,6 @@ serial@5a060000 {
 	...
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_lpuart0>;
-	clocks = <&clk IMX8QXP_UART0_CLK>,
-		 <&clk IMX8QXP_UART0_IPG_CLK>;
-	clock-names = "per", "ipg";
+	clocks = <&uart0_clk>;
 	power-domains = <&pd IMX_SC_R_UART_0>;
 };
diff --git a/include/dt-bindings/firmware/imx/rsrc.h b/include/dt-bindings/firmware/imx/rsrc.h
index 4481f2d..f650fc3 100644
--- a/include/dt-bindings/firmware/imx/rsrc.h
+++ b/include/dt-bindings/firmware/imx/rsrc.h
@@ -556,4 +556,21 @@
 #define IMX_SC_R_VPU			540
 #define IMX_SC_R_LAST			541
 
+/*
+ * Defines for SC PM CLK
+ */
+#define IMX_SC_PM_CLK_SLV_BUS		0	/* Slave bus clock */
+#define IMX_SC_PM_CLK_MST_BUS		1	/* Master bus clock */
+#define IMX_SC_PM_CLK_PER		2	/* Peripheral clock */
+#define IMX_SC_PM_CLK_PHY		3	/* Phy clock */
+#define IMX_SC_PM_CLK_MISC		4	/* Misc clock */
+#define IMX_SC_PM_CLK_MISC0		0	/* Misc 0 clock */
+#define IMX_SC_PM_CLK_MISC1		1	/* Misc 1 clock */
+#define IMX_SC_PM_CLK_MISC2		2	/* Misc 2 clock */
+#define IMX_SC_PM_CLK_MISC3		3	/* Misc 3 clock */
+#define IMX_SC_PM_CLK_MISC4		4	/* Misc 4 clock */
+#define IMX_SC_PM_CLK_CPU		2	/* CPU clock */
+#define IMX_SC_PM_CLK_PLL		4	/* PLL */
+#define IMX_SC_PM_CLK_BYPASS		4	/* Bypass clock */
+
 #endif /* __DT_BINDINGS_RSCRC_IMX_H */
-- 
2.7.4