Re: [PATCH linux v7 3/6] hwmon: occ: Add I2C transport implementation for SCOM operations

[Eddie James]

On 02/09/2017 11:31 PM, Joel Stanley wrote:
> On Wed, Feb 8, 2017 at 9:40 AM,<eajames@xxxxxxxxxxxxxxxxxx>  wrote:
> > From: "Edward A. James"<eajames@xxxxxxxxxx>
> >
> > Add functions to send SCOM operations over I2C bus. The BMC can
> > communicate with the Power8 host processor over I2C, but needs to use SCOM
> > operations in order to access the OCC register space.
> This doesn't need to be separate from the p8_occ_i2c.c file. You can
> remove a layer of function calls by merging this in and having these
> be your getscom putscom bus_ops callbacks.

The purpose of having this separate was so that we could do the scom 
address shift for p8 separately.

> > Signed-off-by: Edward A. James<eajames@xxxxxxxxxx>
> > Signed-off-by: Andrew Jeffery<andrew@xxxxxxxx>
> > ---
> >   drivers/hwmon/occ/occ_scom_i2c.c | 77 ++++++++++++++++++++++++++++++++++++++++
> >   drivers/hwmon/occ/occ_scom_i2c.h | 26 ++++++++++++++
> >   2 files changed, 103 insertions(+)
> >   create mode 100644 drivers/hwmon/occ/occ_scom_i2c.c
> >   create mode 100644 drivers/hwmon/occ/occ_scom_i2c.h
> >
> > diff --git a/drivers/hwmon/occ/occ_scom_i2c.c b/drivers/hwmon/occ/occ_scom_i2c.c
> > new file mode 100644
> > index 0000000..74bd6ff
> > --- /dev/null
> > +++ b/drivers/hwmon/occ/occ_scom_i2c.c
> > @@ -0,0 +1,77 @@
> > +
> > +int occ_i2c_getscom(void *bus, u32 address, u64 *data)
> > +{
> > +       ssize_t rc;
> > +       u64 buf;
> If you add endianness annotations sparse can check your types are
> consistent. The warning looks like this:
>
> make C=2 drivers/hwmon/occ/occ_scom_i2c.o
> drivers/hwmon/occ/occ_scom_i2c.c:48:17: warning: cast to restricted __be64
>
> Which tells you it expects the type you pass to be64_to_cpu to be __be64.
>
>
> > +       struct i2c_client *client = bus;
> > +       struct i2c_msg msgs[2];
> > +
> > +       msgs[0].addr = client->addr;
> > +       msgs[0].flags = client->flags & I2C_M_TEN;
> > +       msgs[0].len = sizeof(u32);
> > +       msgs[0].buf = (char *)&address;
> > +
> > +       msgs[1].addr = client->addr;
> > +       msgs[1].flags = client->flags & I2C_M_TEN;
> > +       msgs[1].flags |= I2C_M_RD;
> I first thought you had made a mistake here. Instead you could do:
>
>         msgs[1].flags = client->flags & I2C_M_TEN | I2C_M_RD;

Sure. Was just copying i2c_master_recv.

> > +       msgs[1].len = sizeof(u64);
> > +       msgs[1].buf = (char *)&buf;
> > +
> > +       rc = i2c_transfer(client->adapter, msgs, 2);
> > +       if (rc < 0)
> > +               return rc;
> > +