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* [PATCH V2] dt-bindings: mailbox: add doorbell support to ARM MHU
@ 2020-09-09  6:19 Viresh Kumar
  2020-09-09 19:35 ` Rob Herring
  0 siblings, 1 reply; 3+ messages in thread
From: Viresh Kumar @ 2020-09-09  6:19 UTC (permalink / raw)
  To: Rob Herring, Jassi Brar
  Cc: devicetree, Vincent Guittot, Arnd Bergmann, Viresh Kumar,
	linux-kernel, Bjorn Andersson, Sudeep Holla, Frank Rowand,
	linux-arm-kernel

From: Sudeep Holla <sudeep.holla@arm.com>

The ARM MHU's reference manual states following:

"The MHU drives the signal using a 32-bit register, with all 32 bits
logically ORed together. The MHU provides a set of registers to enable
software to set, clear, and check the status of each of the bits of this
register independently.  The use of 32 bits for each interrupt line
enables software to provide more information about the source of the
interrupt. For example, each bit of the register can be associated with
a type of event that can contribute to raising the interrupt."

This patch thus extends the MHU controller's DT binding to add support
for doorbell mode.

Though the same MHU hardware controller is used in the two modes, A new
compatible string is added here to represent the combination of the MHU
hardware and the firmware sitting on the other side (which expects each
bit to represent a different signal now).

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Co-developed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
V2:
- New compatible string and minor reformatting.
- Not sending as RFC anymore.

 .../devicetree/bindings/mailbox/arm-mhu.txt   | 44 +++++++++++++++++--
 1 file changed, 41 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/mailbox/arm-mhu.txt b/Documentation/devicetree/bindings/mailbox/arm-mhu.txt
index 4971f03f0b33..1adc441a2c63 100644
--- a/Documentation/devicetree/bindings/mailbox/arm-mhu.txt
+++ b/Documentation/devicetree/bindings/mailbox/arm-mhu.txt
@@ -10,21 +10,41 @@ STAT register and the remote clears it after having read the data.
 The last channel is specified to be a 'Secure' resource, hence can't be
 used by Linux running NS.
 
+Doorbell mode: The MHU drives the interrupt signal using a 32-bit
+register, with all 32-bits logically ORed together. It provides a set of
+registers to enable software to set, clear and check the status of each
+of the bits of this register independently. The use of 32 bits per
+interrupt line enables software to provide more information about the
+source of the interrupt. For example, each bit of the register can be
+associated with a type of event that can contribute to raising the
+interrupt. Each of the 32-bits can be used as "doorbell" to alert the
+remote processor.
+
 Mailbox Device Node:
 ====================
 
 Required properties:
 --------------------
-- compatible:		Shall be "arm,mhu" & "arm,primecell"
+- compatible:		Shall be "arm,mhu" (in data transfer mode) or
+			"arm,mhu-doorbell" (in doorbell mode) and
+			"arm,primecell".
 - reg:			Contains the mailbox register address range (base
 			address and length)
-- #mbox-cells		Shall be 1 - the index of the channel needed.
+- #mbox-cells		Shall be 1 - the index of the channel needed,
+			when used in data transfer mode.
+			Shall be 2 - the index of the channel needed, and
+			the index of the doorbell bit within the
+			channel, when used in doorbell mode.
 - interrupts:		Contains the interrupt information corresponding to
-			each of the 3 links of MHU.
+			each of the 3 physical channels of MHU namely low
+			priority non-secure, high priority non-secure and
+			secure channels.
 
 Example:
 --------
 
+1. In data transfer mode
+
 	mhu: mailbox@2b1f0000 {
 		#mbox-cells = <1>;
 		compatible = "arm,mhu", "arm,primecell";
@@ -41,3 +61,21 @@ used by Linux running NS.
 		reg = <0 0x2e000000 0x4000>;
 		mboxes = <&mhu 1>; /* HP-NonSecure */
 	};
+
+2. In doorbell mode
+
+	mhu: mailbox@2b1f0000 {
+		#mbox-cells = <2>;
+		compatible = "arm,mhu-doorbell", "arm,primecell";
+		reg = <0 0x2b1f0000 0x1000>;
+		interrupts = <0 36 4>, /* LP-NonSecure */
+			     <0 35 4>; /* HP-NonSecure */
+		clocks = <&clock 0 2 1>;
+		clock-names = "apb_pclk";
+	};
+
+	mhu_client: scb@2e000000 {
+		compatible = "arm,scpi";
+		reg = <0 0x2e000000 0x200>;
+		mboxes = <&mhu 1 4>; /* HP-NonSecure 5th doorbell bit */
+	};
-- 
2.25.0.rc1.19.g042ed3e048af


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^ permalink raw reply related	[flat|nested] 3+ messages in thread
* Re: [PATCH V2] dt-bindings: mailbox: add doorbell support to ARM MHU
  2020-09-09  6:19 [PATCH V2] dt-bindings: mailbox: add doorbell support to ARM MHU Viresh Kumar
@ 2020-09-09 19:35 ` Rob Herring
  2020-09-10  9:53   ` Viresh Kumar
  0 siblings, 1 reply; 3+ messages in thread
From: Rob Herring @ 2020-09-09 19:35 UTC (permalink / raw)
  To: Viresh Kumar
  Cc: devicetree, Vincent Guittot, Arnd Bergmann, Jassi Brar,
	linux-kernel, Bjorn Andersson, Sudeep Holla, Frank Rowand,
	linux-arm-kernel

On Wed, Sep 9, 2020 at 12:19 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> From: Sudeep Holla <sudeep.holla@arm.com>
>
> The ARM MHU's reference manual states following:
>
> "The MHU drives the signal using a 32-bit register, with all 32 bits
> logically ORed together. The MHU provides a set of registers to enable
> software to set, clear, and check the status of each of the bits of this
> register independently.  The use of 32 bits for each interrupt line
> enables software to provide more information about the source of the
> interrupt. For example, each bit of the register can be associated with
> a type of event that can contribute to raising the interrupt."
>
> This patch thus extends the MHU controller's DT binding to add support
> for doorbell mode.
>
> Though the same MHU hardware controller is used in the two modes, A new
> compatible string is added here to represent the combination of the MHU
> hardware and the firmware sitting on the other side (which expects each
> bit to represent a different signal now).
>
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> Co-developed-by: Viresh Kumar <viresh.kumar@linaro.org>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> V2:
> - New compatible string and minor reformatting.

Fine with me despite whatever I may have said in the past. Whatever
puts this to rest finally.

> - Not sending as RFC anymore.
>
>  .../devicetree/bindings/mailbox/arm-mhu.txt   | 44 +++++++++++++++++--
>  1 file changed, 41 insertions(+), 3 deletions(-)

I'd really like this converted to schema first given it's more than a
minor change, but I don't want to hold things up. (Though, where's the
new driver?)

> diff --git a/Documentation/devicetree/bindings/mailbox/arm-mhu.txt b/Documentation/devicetree/bindings/mailbox/arm-mhu.txt
> index 4971f03f0b33..1adc441a2c63 100644
> --- a/Documentation/devicetree/bindings/mailbox/arm-mhu.txt
> +++ b/Documentation/devicetree/bindings/mailbox/arm-mhu.txt
> @@ -10,21 +10,41 @@ STAT register and the remote clears it after having read the data.
>  The last channel is specified to be a 'Secure' resource, hence can't be
>  used by Linux running NS.
>
> +Doorbell mode: The MHU drives the interrupt signal using a 32-bit
> +register, with all 32-bits logically ORed together. It provides a set of
> +registers to enable software to set, clear and check the status of each
> +of the bits of this register independently. The use of 32 bits per
> +interrupt line enables software to provide more information about the
> +source of the interrupt. For example, each bit of the register can be
> +associated with a type of event that can contribute to raising the
> +interrupt. Each of the 32-bits can be used as "doorbell" to alert the
> +remote processor.
> +
>  Mailbox Device Node:
>  ====================
>
>  Required properties:
>  --------------------
> -- compatible:          Shall be "arm,mhu" & "arm,primecell"
> +- compatible:          Shall be "arm,mhu" (in data transfer mode) or
> +                       "arm,mhu-doorbell" (in doorbell mode) and
> +                       "arm,primecell".
>  - reg:                 Contains the mailbox register address range (base
>                         address and length)
> -- #mbox-cells          Shall be 1 - the index of the channel needed.
> +- #mbox-cells          Shall be 1 - the index of the channel needed,
> +                       when used in data transfer mode.
> +                       Shall be 2 - the index of the channel needed, and
> +                       the index of the doorbell bit within the
> +                       channel, when used in doorbell mode.
>  - interrupts:          Contains the interrupt information corresponding to
> -                       each of the 3 links of MHU.
> +                       each of the 3 physical channels of MHU namely low
> +                       priority non-secure, high priority non-secure and
> +                       secure channels.
>
>  Example:
>  --------
>
> +1. In data transfer mode
> +
>         mhu: mailbox@2b1f0000 {
>                 #mbox-cells = <1>;
>                 compatible = "arm,mhu", "arm,primecell";
> @@ -41,3 +61,21 @@ used by Linux running NS.
>                 reg = <0 0x2e000000 0x4000>;
>                 mboxes = <&mhu 1>; /* HP-NonSecure */
>         };
> +
> +2. In doorbell mode
> +
> +       mhu: mailbox@2b1f0000 {
> +               #mbox-cells = <2>;
> +               compatible = "arm,mhu-doorbell", "arm,primecell";
> +               reg = <0 0x2b1f0000 0x1000>;
> +               interrupts = <0 36 4>, /* LP-NonSecure */
> +                            <0 35 4>; /* HP-NonSecure */

The binding says there are 3 interrupts.

> +               clocks = <&clock 0 2 1>;
> +               clock-names = "apb_pclk";
> +       };
> +
> +       mhu_client: scb@2e000000 {
> +               compatible = "arm,scpi";
> +               reg = <0 0x2e000000 0x200>;
> +               mboxes = <&mhu 1 4>; /* HP-NonSecure 5th doorbell bit */
> +       };
> --
> 2.25.0.rc1.19.g042ed3e048af
>

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^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: [PATCH V2] dt-bindings: mailbox: add doorbell support to ARM MHU
  2020-09-09 19:35 ` Rob Herring
@ 2020-09-10  9:53   ` Viresh Kumar
  0 siblings, 0 replies; 3+ messages in thread
From: Viresh Kumar @ 2020-09-10  9:53 UTC (permalink / raw)
  To: Rob Herring
  Cc: devicetree, Vincent Guittot, Arnd Bergmann, Jassi Brar,
	linux-kernel, Bjorn Andersson, Sudeep Holla, Frank Rowand,
	linux-arm-kernel

On 09-09-20, 13:35, Rob Herring wrote:
> I'd really like this converted to schema first given it's more than a
> minor change, but I don't want to hold things up. (Though, where's the
> new driver?)

Sudeep will re-work his older patches to get the separate driver ready
for inclusion. We were blocked on this idea for ever and so I didn't
try playing with it until now :)

-- 
viresh

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^ permalink raw reply	[flat|nested] 3+ messages in thread
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2020-09-09  6:19 [PATCH V2] dt-bindings: mailbox: add doorbell support to ARM MHU Viresh Kumar
2020-09-09 19:35 ` Rob Herring
2020-09-10  9:53   ` Viresh Kumar

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