linux-kernel - RE: [PATCH v2 2/2] misc: Add iop driver for Sunplus SP7021

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Message-ID: <2e7d5df0cbe74f2697709ed3e8c94b0b@sphcmbx02.sunplus.com.tw>
Date:   Mon, 6 Dec 2021 08:22:01 +0000
From:   Tony Huang 黃懷厚 <tony.huang@...plus.com>
To:     Greg KH <gregkh@...uxfoundation.org>
CC:     Tony Huang <tonyhuang.sunplus@...il.com>,
        "derek.kiernan@...inx.com" <derek.kiernan@...inx.com>,
        "dragan.cvetic@...inx.com" <dragan.cvetic@...inx.com>,
        "arnd@...db.de" <arnd@...db.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Wells Lu 呂芳騰 <wells.lu@...plus.com>
Subject: RE: [PATCH v2 2/2] misc: Add iop driver for Sunplus SP7021

Dear Greg KH:

> -----Original Message-----
> From: Greg KH <gregkh@...uxfoundation.org>
> Sent: Monday, December 6, 2021 4:07 PM
> To: Tony Huang 黃懷厚 <tony.huang@...plus.com>
> Cc: Tony Huang <tonyhuang.sunplus@...il.com>; derek.kiernan@...inx.com;
> dragan.cvetic@...inx.com; arnd@...db.de; linux-kernel@...r.kernel.org;
> robh+dt@...nel.org; devicetree@...r.kernel.org; Wells Lu 呂芳騰
> <wells.lu@...plus.com>
> Subject: Re: [PATCH v2 2/2] misc: Add iop driver for Sunplus SP7021
> 
> On Mon, Dec 06, 2021 at 06:48:46AM +0000, Tony Huang 黃懷厚 wrote:
> > Dear Greg KH, Arnd:
> >
> > > -----Original Message-----
> > > From: Greg KH <gregkh@...uxfoundation.org>
> > > Sent: Friday, December 3, 2021 6:39 PM
> > > To: Tony Huang <tonyhuang.sunplus@...il.com>
> > > Cc: derek.kiernan@...inx.com; dragan.cvetic@...inx.com;
> > > arnd@...db.de; linux-kernel@...r.kernel.org; robh+dt@...nel.org;
> > > devicetree@...r.kernel.org; Wells Lu 呂芳騰 <wells.lu@...plus.com>;
> > > Tony Huang 黃懷厚
> > > <tony.huang@...plus.com>
> > > Subject: Re: [PATCH v2 2/2] misc: Add iop driver for Sunplus SP7021
> > >
> > > On Fri, Dec 03, 2021 at 11:48:45AM +0800, Tony Huang wrote:
> > > > IOP (IO Processor) embedded inside SP7021 which is used as
> > > > Processor for I/O control, RTC wake-up and cooperation with CPU &
> > > > PMC in power management purpose.
> > > > The IOP core is DQ8051, so also named IOP8051, it supports
> > > > dedicated JTAG debug pins which share with SP7021.
> > > > In standby mode operation, the power spec reach 400uA.
> > > >
> > > > Signed-off-by: Tony Huang <tonyhuang.sunplus@...il.com>
> > > > ---
> > > > Changes in v2:
> > > >  - Addressed comments from Arnd Bergmann.
> > > >  - Addressed comments from Greg KH.
> > > >  - Addressed comments from kernel test robot.
> > > >
> > > >  MAINTAINERS                    |   1 +
> > > >  drivers/misc/Kconfig           |   1 +
> > > >  drivers/misc/Makefile          |   1 +
> > > >  drivers/misc/iop/Kconfig       |  13 ++
> > > >  drivers/misc/iop/Makefile      |   6 +
> > >
> > > Why do you need a subdirectory for a single .c file?
> > >
> >
> > 1. Currently my bin file is placed in the root file system. I need to
> > wait for the kernel booting to succeed before loading the bin code.
> 
> What "bin file"?
> 

IOP MODULE EXECUTES 8051 CODE
Source code should reserve SDRAM memory area for IOP module code. 8051 bin file normal code and standby code can be placed in this area. The location area can be select by user.
Normal code: Monitor CPU commands.
Standby code: For RTC wake up, cooperation with CPU&PMC in power management When the system enters standby mode, 8051 bin file should be moved to I_Cache.
I_Cache has 16K only. Standby code cannot exceed 16K.
When the IOP module is mounted, CPU load 8051 codes (normal.bin) into memory.
Iop_base_addr_l and iop_base_addr_h specify address.
During system boot up, when the IOP is mounted, it will load 8051 normal code and start execute 8051 code.

> > 2. In addition, I need the kernel booting process to be able to mount
> > the iop module and load bin file.I need to put bin file in /iop.
> 
> That is an odd directory location.
> 
> > Do you have a good way to load bin code during kernel booting?
> 
> Is this firmware?  Put it in the normal location for firware that the kernel
> expects to see.
> 
> thanks,
> 
> greg k-h