linux-kernel - Re: [PATCH v6 07/23] drivers/fsi: Implement slave initialisation

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Message-Id: <7c0b7c6d-6d1b-b36d-b886-1130c35d0964@linux.vnet.ibm.com>
Date:   Tue, 2 May 2017 13:58:59 -0500
From:   Christopher Bostic <cbostic@...ux.vnet.ibm.com>
To:     Joel Stanley <joel@....id.au>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Russell King <linux@...linux.org.uk>, rostedt@...dmis.org,
        mingo@...hat.com, Greg KH <gregkh@...uxfoundation.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel@...ts.infradead.org, Jeremy Kerr <jk@...abs.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Andrew Jeffery <andrew@...id.au>,
        Alistair Popple <alistair@...ple.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: Re: [PATCH v6 07/23] drivers/fsi: Implement slave initialisation



On 5/2/17 1:24 AM, Joel Stanley wrote:
> On Tue, Apr 11, 2017 at 5:16 AM, Christopher Bostic
> <cbostic@...ux.vnet.ibm.com> wrote:
>> From: Jeremy Kerr <jk@...abs.org>
>>
>> Implement fsi_slave_init: if we can read a chip ID, create fsi_slave
>> devices and register with the driver core.
>>
>> Includes changes from Chris Bostic <cbostic@...ux.vnet.ibm.com>.
>>
>> Signed-off-by: Jeremy Kerr <jk@...abs.org>
>> Signed-off-by: Chris Bostic <cbostic@...ux.vnet.ibm.com>
>> Signed-off-by: Joel Stanley <joel@....id.au>
>> ---
>>   drivers/fsi/fsi-core.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++--
>>   1 file changed, 64 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
>> index 6e1cfdf..c705ca2 100644
>> --- a/drivers/fsi/fsi-core.c
>> +++ b/drivers/fsi/fsi-core.c
>> @@ -17,9 +17,12 @@
>>   #include <linux/fsi.h>
>>   #include <linux/idr.h>
>>   #include <linux/module.h>
>> +#include <linux/slab.h>
>>
>>   #include "fsi-master.h"
>>
>> +#define FSI_SLAVE_SIZE_23b             0x800000
>> +
>>   static DEFINE_IDA(master_ida);
>>
>>   struct fsi_slave {
>> @@ -114,11 +117,70 @@ static int fsi_slave_write(struct fsi_slave *slave, uint32_t addr,
>>                          addr, val, size);
>>   }
>>
>> +static void fsi_slave_release(struct device *dev)
>> +{
>> +       struct fsi_slave *slave = to_fsi_slave(dev);
>> +
>> +       kfree(slave);
>> +}
>> +
>>   static int fsi_slave_init(struct fsi_master *master, int link, uint8_t id)
>>   {
>> -       /* todo: initialise slave device, perform engine scan */
>> +       struct fsi_slave *slave;
>> +       uint32_t chip_id;
>> +       uint8_t crc;
>> +       int rc;
>> +
>> +       /* Currently, we only support single slaves on a link, and use the
>> +        * full 23-bit address range
>> +        */
>> +       if (id != 0)
>> +               return -EINVAL;
>> +
>> +       rc = fsi_master_read(master, link, id, 0, &chip_id, sizeof(chip_id));
>> +       if (rc) {
>> +               dev_warn(&master->dev, "can't read slave %02x:%02x %d\n",
>> +                               link, id, rc);
> When I boot a system with this driver loaded, I get his warning:
>
> [    9.740000] usbhid: USB HID core driver
> [    9.840000]  fsi0: can't read slave 00:00 -5
> [    9.840000] NET: Registered protocol family 10
>
> Two things:
>
> There's a space in front of "fsi0".

Hi Joel,

Will correct.
>
> This warning isn't useful at that point. The slave is not readable as
> the FSI master is not present (the P9 hasn't been turned on). Can we
> avoid printing the warning at boot?

Yes agreed.  Will remove the warning in that case.

Thanks,
Chris
>
> Cheers,
>
> Joel
>
>> +               return -ENODEV;
>> +       }
>> +       chip_id = be32_to_cpu(chip_id);
>> +
>> +       crc = fsi_crc4(0, chip_id, 32);
>> +       if (crc) {
>> +               dev_warn(&master->dev, "slave %02x:%02x invalid chip id CRC!\n",
>> +                               link, id);
>> +               return -EIO;
>> +       }
>> +
>> +       dev_info(&master->dev, "fsi: found chip %08x at %02x:%02x:%02x\n",
>> +                       chip_id, master->idx, link, id);
>> +
>> +       /* We can communicate with a slave; create the slave device and
>> +        * register.
>> +        */
>> +       slave = kzalloc(sizeof(*slave), GFP_KERNEL);
>> +       if (!slave)
>> +               return -ENOMEM;
>> +
>> +       slave->master = master;
>> +       slave->dev.parent = &master->dev;
>> +       slave->dev.release = fsi_slave_release;
>> +       slave->link = link;
>> +       slave->id = id;
>> +       slave->size = FSI_SLAVE_SIZE_23b;
>> +
>> +       dev_set_name(&slave->dev, "slave@...x:%02x", link, id);
>> +       rc = device_register(&slave->dev);
>> +       if (rc < 0) {
>> +               dev_warn(&master->dev, "failed to create slave device: %d\n",
>> +                               rc);
>> +               put_device(&slave->dev);
>> +               return rc;
>> +       }
>> +
>> +       /* todo: perform engine scan */
>>
>> -       return -ENODEV;
>> +       return rc;
>>   }
>>
>>   /* FSI master support */
>> --
>> 1.8.2.2
>>