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

Joel Stanley
2017-02-10T05:31:53Z

On Wed, Feb 8, 2017 at 9:40 AM, <eajames@linux.vnet.ibm.com> wrote:
> From: "Edward A. James" <eajames@us.ibm.com>
>
> 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.

> Signed-off-by: Edward A. James <eajames@us.ibm.com>
> Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
> ---
> 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;

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