RE: [PATCH v1 12/18] hw/arm/aspeed_ast27x0: Support two levels of INTC controllers for AST2700 A1

[Jamin Lin]

Hi Andrew,

> -----Original Message-----
> From: Andrew Jeffery <andrew@codeconstruct.com.au>
> Sent: Thursday, January 30, 2025 12:20 PM
> To: Jamin Lin <jamin_lin@aspeedtech.com>; Cédric Le Goater <clg@kaod.org>;
> Peter Maydell <peter.maydell@linaro.org>; Steven Lee
> <steven_lee@aspeedtech.com>; Troy Lee <leetroy@gmail.com>; Joel Stanley
> <joel@jms.id.au>; open list:ASPEED BMCs <qemu-arm@nongnu.org>; open
> list:All patches CC here <qemu-devel@nongnu.org>
> Cc: Troy Lee <troy_lee@aspeedtech.com>; Yunlin Tang
> <yunlin.tang@aspeedtech.com>
> Subject: Re: [PATCH v1 12/18] hw/arm/aspeed_ast27x0: Support two levels of
> INTC controllers for AST2700 A1
> 
> On Tue, 2025-01-21 at 15:04 +0800, Jamin Lin wrote:
> > The design of INTC controllers has significantly changed in AST2700 A1.
> >
> > There are a total of 480 interrupt sources in AST2700 A1. For
> > interrupt numbers from 0 to 127, they can route directly to PSP, SSP,
> > and TSP. Due to the limitation of interrupt numbers of processors, the
> > interrupts are merged every
> > 32 sources for interrupt numbers greater than 127.
> >
> > There are two levels of interrupt controllers, INTC0 and INTC1. The
> > interrupt sources of INTC0 are the interrupt numbers from INTC_0 to
> > INTC_127 and interrupts from INTC1. The interrupt sources of INTC1 are
> > the interrupt numbers greater than INTC_127. INTC1 controls the interrupts
> INTC_128 to INTC_319 only.
> >
> > Currently, only GIC 192 to 201 are supported, and their source
> > interrupts are from INTC1 and connected to INTC0 at input pin 0 and
> > output pins 0 to 9 for GIC 192-201.
> >
> > To support both AST2700 A1 and A0, INTC0 input pins 1 to 9 and output
> > pins
> > 10 to 18 remain to support GIC 128-136, which source interrupts from INTC0.
> > These will be removed if we decide not to support AST2700 A0 in the future.
> >
> > +---------------------------------------------------------------------------------------+
> > >                            AST2700 A1
> Design
> > > |
> >
> >
> 
> > > |
> >
> >                     +--------------------------+
> 
> > > |
> >
> >                     |         INTC1            |
> 
> > > +---------------+             |
> >
> >                     |                          |
>       |
> > > orgates[0]   |             |
> > >    orgates[0]+----> |inpin[0]+------->outpin[0]+------> |
> 0
> > > |             |
> > >    orgates[1]|----> |inpin[1]|------->outpin[1]|------> | 1   0-31
> > > bits +--+          |
> > >    orgates[2]|----> |inpin[2]|------->outpin[2]|------> |
> 2
> > > |  |          |
> > >    orgates[3]|----> |inpin[3]|------->outpin[3]|------> |
> 3
> > > |  |          |
> > >    orgates[4]|----> |inpin[4]|------->outpin[4]|------> |
> 4
> > > |  |          |
> > >    orgates[5]+----> |inpin[5]+------->outpin[5]+------> |
> 5
> > > |  |          |
> >
> >                     |                          |
> 
> > > |---------------|  |          |
> >
> >                     +--------------------------+
> 
> > > |          |
> > >
> > > +-------------------------------------------------------------------
> > > ----|          |
> >
> >    |
> 
> > > |
> >
> >    |
> 
> > > |
> > >    |                +------------------------------+
> > > +-----------------+    |
> >
> >    |                |            INTC0             |
>            |
> > > GIC         |    |
> > >    |                |inpin[0:0]--------->outpin[0] +--------->
> |192
> > > |    |
> > >    |                |inpin[0:1]|-------->outpin[1] |--------->
> |193
> > > |    |
> > >    |                |inpin[0:2]|-------->outpin[2] |--------->
> |194
> > > |    |
> > >    |                |inpin[0:3]|-------->outpin[3] |--------->
> |195
> > > |    |
> > >    >--------------> |inpin[0:4]|-------->outpin[4] |--------->
> |196
> > > |    |
> > >                     |inpin[0:5]|-------->outpin[5] |--------->
> |197
> > > |    |
> > >                     |inpin[0:6]|-------->outpin[6] |--------->
> |198
> > > |    |
> > >                     |inpin[0:7]|-------->outpin[7] |--------->
> |199
> > > |    |
> > >                     |inpin[0:8]|-------->outpin[8] |--------->
> |200
> > > |    |
> > >                     |inpin[0:9]|-------->outpin[9] |--------->
> |201
> > > |    |
> > +---------------------------------------------------------------------------------------+
> > +---------------------------------------------------------------------------------------+
> > >   orgates[1]|-----> |inpin[1]|---------->outpin[10]|--------->
> |128
> > > |    |
> > >   orgates[2]|-----> |inpin[2]|---------->outpin[11]|--------->
> |129
> > > |    |
> > >   orgates[3]|-----> |inpin[3]|---------->outpin[12]|--------->
> |130
> > > |    |
> > >   orgates[4]|-----> |inpin[4]|---------->outpin[13]|--------->
> |131
> > > |    |
> > >   orgates[5]|-----> |inpin[5]|---------->outpin[14]|--------->
> |132
> > > |    |
> > >   orgates[6]|-----> |inpin[6]|---------->outpin[15]|--------->
> |133
> > > |    |
> > >   orgates[7]|-----> |inpin[7]|---------->outpin[16]|--------->
> |134
> > > |    |
> > >   orgates[8]|-----> |inpin[8]|---------->outpin[17]|--------->
> |135
> > > |    |
> > >   orgates[9]+-----> |inpin[9]|---------->outpin[18]+--------->
> |136
> > > |    |
> > >                     +------------------------------+
> > > +-----------------+    |
> >
> >
> 
> > > |
> > >                     AST2700 A0
> Design
> 
> > > |
> >
> >
> 
> > > |
> > +---------------------------------------------------------------------------------------+
> >
> 
> Okay, so I think this is the diagram and discussion I asked for as 
> documentation
> earlier. I still prefer it doesn't just live in a commit message, that you 
> pull it out
> to a separate document that we can easily point to and evolve.
> 
INTC drivers owners update DTS binding document here, 
https://patchwork.kernel.org/project/linux-arm-kernel/patch/20241016022410.1154574-2-kevin_chen@aspeedtech.com/


> I'm a little hazy on some of your notation in diagram though. Can you explain
> your use of pipes ("|"), plusses ("+"), the "orgates" to the left of INTC1 
> (what
> are they ORing?), and the choice of 5 lines into the "orgates[0]" box? Also 
> why
> does the "orgates[0]" arrow point where it does on INTC0?
> 
I created this block diagram using the asciiflow tool and both ("I") and "("+") 
symbols are identical.
I will update the diagram and replace ("+") with ("|").
Sorry to make you confuse.

The design of the OR gates for GICINT 196 is as follows:
It has interrupt sources ranging from 0 to 31, with its output pin connected to 
INTC_IO "T0 GICINTC_192".
The output pin is then connected to INTC_CPU "GIC_192_201" at bit 0, and its 
bit 0 output should be connected to GIC 192.

The design of INTC_CPU GIC_192_201 have 10 output pins, mapped as following:
Bit 0 --> GIC 192
BIT 1 -> GIC 193
BIT 2-> GIC 194

Our firmware only utilizes bits 0 to 5, so I have only illustrated bits 0 to 5 
in the diagram. However, I have implemented bits 0 to 9 in the code.

Then, orgates[0] "or" the output pins of INTC_IO (To GIC192, To GIC193, To 
GIC194, To GIC195, To GIC196) 

ETH1    +-----------+
+--------v+0         3+
  ETH2    |          4|
+-------->+1         5|
  ETH3    |          6|
+-------->+2        19|
  UART0   |         20|
+-------->+7        21|
  UART1   |         22|
+-------->+8        23|
  UART2   |         24|
+-------->+9        25|
  UART3   |         26|
+--------->10       27|
  UART5   |         28|
+-------->+11       29|
  UART6   |           |
+-------->+12       30|
  UART7   |         31|
+-------->+13         |
  UART8   |  OR[0:31] |
+--------->14         |
  UART9   |           |
+-------->+15         |
  UART10  |           |
+-------->+16         |
  UART11  |           |
+-------->+17         |
  UART12  |           |
+--------->18         |
          |           |
          |           |
          |           |
          +-----------+

https://github.com/AspeedTech-BMC/linux/blob/aspeed-master-v6.6/arch/arm64/boot/dts/aspeed/aspeed-g7.dtsi#L483
https://github.com/AspeedTech-BMC/linux/blob/aspeed-master-v6.6/arch/arm64/boot/dts/aspeed/aspeed-g7.dtsi#L1610

Thanks-Jamin
> Andrew