Re: [PATCH 14/18] hw/net: cadence_gem: Add a new 'phy-addr' property

[Bin Meng]

On Sat, Aug 15, 2020 at 5:06 PM Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
>
> On 8/14/20 6:40 PM, Bin Meng wrote:
> > From: Bin Meng <bin.meng@windriver.com>
> >
> > At present the PHY address of the PHY connected to GEM is hard-coded
> > to either 23 (BOARD_PHY_ADDRESS) or 0. This might not be the case for
> > all boards. Add a new 'phy-addr' property so that board can specify
> > the PHY address for each GEM instance.
> >
> > Signed-off-by: Bin Meng <bin.meng@windriver.com>
> > ---
> >
> >  hw/net/cadence_gem.c         | 7 +++++--
> >  include/hw/net/cadence_gem.h | 2 ++
> >  2 files changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/net/cadence_gem.c b/hw/net/cadence_gem.c
> > index a93b5c0..9fa03de 100644
> > --- a/hw/net/cadence_gem.c
> > +++ b/hw/net/cadence_gem.c
> > @@ -1446,7 +1446,8 @@ static uint64_t gem_read(void *opaque, hwaddr offset, 
> > unsigned size)
> >              uint32_t phy_addr, reg_num;
> >
> >              phy_addr = (retval & GEM_PHYMNTNC_ADDR) >> 
> > GEM_PHYMNTNC_ADDR_SHFT;
> > -            if (phy_addr == BOARD_PHY_ADDRESS || phy_addr == 0) {
> > +            if (phy_addr == BOARD_PHY_ADDRESS || phy_addr == 0 ||
> > +                phy_addr == s->phy_addr) {
> >                  reg_num = (retval & GEM_PHYMNTNC_REG) >> 
> > GEM_PHYMNTNC_REG_SHIFT;
> >                  retval &= 0xFFFF0000;
> >                  retval |= gem_phy_read(s, reg_num);
> > @@ -1569,7 +1570,8 @@ static void gem_write(void *opaque, hwaddr offset, 
> > uint64_t val,
> >              uint32_t phy_addr, reg_num;
> >
> >              phy_addr = (val & GEM_PHYMNTNC_ADDR) >> GEM_PHYMNTNC_ADDR_SHFT;
> > -            if (phy_addr == BOARD_PHY_ADDRESS || phy_addr == 0) {
> > +            if (phy_addr == BOARD_PHY_ADDRESS || phy_addr == 0 ||
> > +                phy_addr == s->phy_addr) {
> >                  reg_num = (val & GEM_PHYMNTNC_REG) >> 
> > GEM_PHYMNTNC_REG_SHIFT;
> >                  gem_phy_write(s, reg_num, val);
> >              }
> > @@ -1682,6 +1684,7 @@ static Property gem_properties[] = {
> >      DEFINE_NIC_PROPERTIES(CadenceGEMState, conf),
> >      DEFINE_PROP_UINT32("revision", CadenceGEMState, revision,
> >                         GEM_MODID_VALUE),
> > +    DEFINE_PROP_UINT8("phy-addr", CadenceGEMState, phy_addr, 0),
>
> This patch would be complete by moving the BOARD_PHY_ADDRESS definition
> to each board using this NIC, and setting the "phy-addr" property to
> this value.

I actually have no idea which board in QEMU is using this special PHY
address instead of default 0.

It looks BOARD_PHY_ADDRESS has been there since the initial version of
the cadence_gem model.

commit e9f186e514a70557d695cadd2c2287ef97737023
Author: Peter A. G. Crosthwaite <peter.crosthwaite@petalogix.com>
Date:   Mon Mar 5 14:39:12 2012 +1000

    cadence_gem: initial version of device model

    Device model for cadence gem ethernet controller.

    Signed-off-by: Peter A. G. Crosthwaite <peter.crosthwaite@petalogix.com>
    Signed-off-by: John Linn <john.linn@xilinx.com>
    Acked-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
    Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>

Later PHY address 0 was added via the following commit:

commit 553893736885e4f2dda424bff3e2200e1b6482a5
Author: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Date:   Thu Apr 3 23:55:19 2014 -0700

    net: cadence_gem: Make phy respond to broadcast

    Phys must respond to address 0 by specification. Implement.

    Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
    Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
    Message-id:
6f4d53b04ddbfb19895bfb61a595e69f1c08859a.1396594056.git.peter.crosthwaite@xilinx.com
    Reviewed-by: Beniamino Galvani <b.galvani@gmail.com>
    Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

I doubt the commit message said that PHYs must respond to address 0. I
am not aware of such specs. The issue was probably that whatever board
2nd commit was tested against did not have a PHY at address
BOARD_PHY_ADDRESS.

+ a couple of Xilinx folks to comment.

>
> >      DEFINE_PROP_UINT8("num-priority-queues", CadenceGEMState,
> >                        num_priority_queues, 1),
> >      DEFINE_PROP_UINT8("num-type1-screeners", CadenceGEMState,
> > diff --git a/include/hw/net/cadence_gem.h b/include/hw/net/cadence_gem.h
> > index 54e646f..01c6189 100644
> > --- a/include/hw/net/cadence_gem.h
> > +++ b/include/hw/net/cadence_gem.h
> > @@ -73,6 +73,8 @@ typedef struct CadenceGEMState {
> >      /* Mask of register bits which are write 1 to clear */
> >      uint32_t regs_w1c[CADENCE_GEM_MAXREG];
> >
> > +    /* PHY address */
> > +    uint8_t phy_addr;
> >      /* PHY registers backing store */
> >      uint16_t phy_regs[32];

Regards,
Bin