On Thu, May 09, 2019 at 04:29:25PM +0200, Andrew Lunn wrote:
> On Wed, May 08, 2019 at 11:13:28PM +0200, Michael Grzeschik wrote:
> > Some microchip phys support the Serial Management Interface Protocol
> > (SMI) for the configuration of the extended register set. We add
> > MII_ADDR_SMI0 as an availabe interface to the mdiobb write and read
> > functions, as this interface can be easy realized using the bitbang mdio
> > driver.
> >
> > Signed-off-by: Sam Ravnborg <s...@ravnborg.org>
> > Signed-off-by: Michael Grzeschik <m.grzesc...@pengutronix.de>
> > ---
> > drivers/net/phy/mdio-bitbang.c | 10 ++++++++++
> > include/linux/phy.h | 12 ++++++++++++
> > 2 files changed, 22 insertions(+)
> >
> > diff --git a/drivers/net/phy/mdio-bitbang.c b/drivers/net/phy/mdio-bitbang.c
> > index 5136275c8e739..a978f8a9a172b 100644
> > --- a/drivers/net/phy/mdio-bitbang.c
> > +++ b/drivers/net/phy/mdio-bitbang.c
> > @@ -22,6 +22,10 @@
> > #define MDIO_READ 2
> > #define MDIO_WRITE 1
> >
> > +#define SMI0_RW_OPCODE 0
> > +#define SMI0_READ_PHY (1 << 4)
> > +#define SMI0_WRITE_PHY (0 << 4)
> > +
> > #define MDIO_C45 (1<<15)
> > #define MDIO_C45_ADDR (MDIO_C45 | 0)
> > #define MDIO_C45_READ (MDIO_C45 | 3)
> > @@ -157,6 +161,9 @@ static int mdiobb_read(struct mii_bus *bus, int phy,
> > int reg)
> > if (reg & MII_ADDR_C45) {
> > reg = mdiobb_cmd_addr(ctrl, phy, reg);
> > mdiobb_cmd(ctrl, MDIO_C45_READ, phy, reg);
> > + } else if (reg & MII_ADDR_SMI0) {
> > + mdiobb_cmd(ctrl, SMI0_RW_OPCODE,
> > + (reg & 0xE0) >> 5 | SMI0_READ_PHY, reg);
> > } else
> > mdiobb_cmd(ctrl, MDIO_READ, phy, reg);
> >
> > @@ -188,6 +195,9 @@ static int mdiobb_write(struct mii_bus *bus, int phy,
> > int reg, u16 val)
> > if (reg & MII_ADDR_C45) {
> > reg = mdiobb_cmd_addr(ctrl, phy, reg);
> > mdiobb_cmd(ctrl, MDIO_C45_WRITE, phy, reg);
> > + } else if (reg & MII_ADDR_SMI0) {
> > + mdiobb_cmd(ctrl, SMI0_RW_OPCODE,
> > + (reg & 0xE0) >> 5 | SMI0_WRITE_PHY, reg);
> > } else
> > mdiobb_cmd(ctrl, MDIO_WRITE, phy, reg);
> >
> > diff --git a/include/linux/phy.h b/include/linux/phy.h
> > index 073fb151b5a99..f011722fbd5c2 100644
> > --- a/include/linux/phy.h
> > +++ b/include/linux/phy.h
> > @@ -199,6 +199,18 @@ static inline const char *phy_modes(phy_interface_t
> > interface)
> > IEEE 802.3ae clause 45 addressing mode used by 10GIGE phy chips. */
> > #define MII_ADDR_C45 (1<<30)
> >
> > +/* Serial Management Interface (SMI) uses the following frame format:
> > + *
> > + * preamble|start|Read/Write| PHY | REG |TA| Data bits |
> > Idle
> > + * |frame| OP code |address |address| | |
> > + * read | 32x1´s | 01 | 00 | 1xRRR | RRRRR |Z0| 00000000DDDDDDDD |
> > Z
> > + * write| 32x1´s | 01 | 00 | 0xRRR | RRRRR |10| xxxxxxxxDDDDDDDD |
> > Z
> > + *
> > + * The register number is encoded with the 5 least significant bits in REG
> > + * and the 3 most significant bits in PHY
> > + */
> > +#define MII_ADDR_SMI0 (1<<31)
> > +
>
> Michael
>
> This is a Micrel Proprietary protocol. So we should reflect this in
> the name. MII_ADDR_MICREL_SMI? Why the 0? Are there different
> versions? Maybe replace all SMI0 with MICREL_SMI in mdio-bitbang.c
There are two variants of the SMI interface.
The KSZ8863/73/93 Products use the above Variant described as "SMI0".
The KSZ8864/95 Products use another layout:
preamble|start|Read/Write| PHY | REG |TA| Data bits | Idle
|frame| OP code |address |address| | |
read | 32x1´s | 01 | 10 | RR11R | RRRRR |Z0| 00000000DDDDDDDD | Z
write| 32x1´s | 01 | 01 | RR11R | RRRRR |10| xxxxxxxxDDDDDDDD | Z
So they describe their write/read operation in the OP code rather then
the PHY address.
We could change the SMI index to SMI_KSZ88X3 for the current SMI0 to
give it a more descriptive name. Beside we never know if Microchip
will add the same protocol to other numbered switches. What naming
would you prefer?
> When i look at this, i don't see how a normal MDIO bus driver is going
> to support this. Only the bit banging driver, or maybe a Micrel MDIO
> bus master hardware driver. So i think the diagram should be placed
> into mdio-bitbang.c, and it would be nice to add a diagram of standard
> SMI.
Right. I will move the description to mdio-bitbang.c.
Thanks,
Michael
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