Re: [PATCH 1/1] hw/i2c/aspeed: Fix old reg slave receive

[Peter Delevoryas]

On Tue, Aug 23, 2022 at 11:23:55AM +0200, Klaus Jensen wrote:
> On Aug 20 15:57, Peter Delevoryas wrote:
> > I think when Klaus ported his slave mode changes from the original patch
> > series to the rewritten I2C module, he changed the behavior of the first
> > byte that is received by the slave device.
> > 
> > What's supposed to happen is that the AspeedI2CBus's slave device's
> > i2c_event callback should run, and if the event is "send_async", then it
> > should populate the byte buffer with the 8-bit I2C address that is being
> > sent to. Since we only support "send_async", the lowest bit should
> > always be 0 (indicating that the master is requesting to send data).
> > 
> > This is the code Klaus had previously, for reference. [1]
> > 
> >     switch (event) {
> >     case I2C_START_SEND:
> >         bus->buf = bus->dev_addr << 1;
> > 
> >         bus->buf &= I2CD_BYTE_BUF_RX_MASK;
> >         bus->buf <<= I2CD_BYTE_BUF_RX_SHIFT;
> > 
> >         bus->intr_status |= (I2CD_INTR_SLAVE_ADDR_RX_MATCH | 
> > I2CD_INTR_RX_DONE);
> >         aspeed_i2c_set_state(bus, I2CD_STXD);
> > 
> >         break;
> > 
> > [1]: 
> > https://lore.kernel.org/qemu-devel/20220331165737.1073520-4-its@irrelevant.dk/
> > 
> > Signed-off-by: Peter Delevoryas <peter@pjd.dev>
> > Fixes: a8d48f59cd021b25 ("hw/i2c/aspeed: add slave device in old register 
> > mode")
> > ---
> >  hw/i2c/aspeed_i2c.c         | 8 +++++---
> >  include/hw/i2c/aspeed_i2c.h | 1 +
> >  2 files changed, 6 insertions(+), 3 deletions(-)
> > 
> > diff --git a/hw/i2c/aspeed_i2c.c b/hw/i2c/aspeed_i2c.c
> > index 42c6d69b82..c166fd20fa 100644
> > --- a/hw/i2c/aspeed_i2c.c
> > +++ b/hw/i2c/aspeed_i2c.c
> > @@ -1131,7 +1131,9 @@ static int aspeed_i2c_bus_slave_event(I2CSlave 
> > *slave, enum i2c_event event)
> >      AspeedI2CBus *bus = ASPEED_I2C_BUS(qbus->parent);
> >      uint32_t reg_intr_sts = aspeed_i2c_bus_intr_sts_offset(bus);
> >      uint32_t reg_byte_buf = aspeed_i2c_bus_byte_buf_offset(bus);
> > -    uint32_t value;
> > +    uint32_t reg_dev_addr = aspeed_i2c_bus_dev_addr_offset(bus);
> > +    uint32_t dev_addr = SHARED_ARRAY_FIELD_EX32(bus->regs, reg_dev_addr,
> > +                                                SLAVE_DEV_ADDR1);
> >  
> >      if (aspeed_i2c_is_new_mode(bus->controller)) {
> >          return aspeed_i2c_bus_new_slave_event(bus, event);
> > @@ -1139,8 +1141,8 @@ static int aspeed_i2c_bus_slave_event(I2CSlave 
> > *slave, enum i2c_event event)
> >  
> >      switch (event) {
> >      case I2C_START_SEND_ASYNC:
> > -        value = SHARED_ARRAY_FIELD_EX32(bus->regs, reg_byte_buf, TX_BUF);
> > -        SHARED_ARRAY_FIELD_DP32(bus->regs, reg_byte_buf, RX_BUF, value << 
> > 1);
> > +        /* Bit[0] == 0 indicates "send". */
> > +        SHARED_ARRAY_FIELD_DP32(bus->regs, reg_byte_buf, RX_BUF, dev_addr 
> > << 1);
> >  
> >          ARRAY_FIELD_DP32(bus->regs, I2CD_INTR_STS, SLAVE_ADDR_RX_MATCH, 1);
> >          SHARED_ARRAY_FIELD_DP32(bus->regs, reg_intr_sts, RX_DONE, 1);
> > diff --git a/include/hw/i2c/aspeed_i2c.h b/include/hw/i2c/aspeed_i2c.h
> > index 300a89b343..adc904d6c1 100644
> > --- a/include/hw/i2c/aspeed_i2c.h
> > +++ b/include/hw/i2c/aspeed_i2c.h
> > @@ -130,6 +130,7 @@ REG32(I2CD_CMD, 0x14) /* I2CD Command/Status */
> >      SHARED_FIELD(M_TX_CMD, 1, 1)
> >      SHARED_FIELD(M_START_CMD, 0, 1)
> >  REG32(I2CD_DEV_ADDR, 0x18) /* Slave Device Address */
> > +    SHARED_FIELD(SLAVE_DEV_ADDR1, 0, 7)
> >  REG32(I2CD_POOL_CTRL, 0x1C) /* Pool Buffer Control */
> >      SHARED_FIELD(RX_COUNT, 24, 5)
> >      SHARED_FIELD(RX_SIZE, 16, 5)
> > -- 
> > 2.37.1
> > 
> 
> Nice catch Peter! I'm not sure how I messed that up like that.
> 
> Reviewed-by: Klaus Jensen <k.jensen@samsung.com>

Thanks Klaus. Just realized I forgot to cc you on this, sorry about
that.