[PATCH linux dev-4.7] drivers: fsi: scom: Add reset functionality and sysfs interface

[Eddie James]

On 02/19/2017 11:42 PM, Joel Stanley wrote:
> On Sat, Feb 18, 2017 at 8:11 AM, Eddie James <eajames at linux.vnet.ibm.com> wrote:
>> From: "Edward A. James" <eajames at us.ibm.com>
>>
>> full reset only
> The commit message needs some work. Use full sentences, explain why
> the patch is required.

Ok.

>
>> Signed-off-by: Edward A. James <eajames at us.ibm.com>
>> ---
>>   drivers/fsi/fsi-scom.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++-
>>   1 file changed, 50 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/fsi/fsi-scom.c b/drivers/fsi/fsi-scom.c
>> index ff8267b..c73bd91 100644
>> --- a/drivers/fsi/fsi-scom.c
>> +++ b/drivers/fsi/fsi-scom.c
>> @@ -32,7 +32,10 @@
>>   #define SCOM_DATA0_REG         0x00
>>   #define SCOM_DATA1_REG         0x04
>>   #define SCOM_CMD_REG           0x08
>> +#define SCOM_FSI2PIB_RESET_REG 0x18
>>   #define SCOM_RESET_REG         0x1C
>> +#define SCOM_COMP_MASK_REG     0x30
>> +#define SCOM_TRUE_MASK_REG     0x34
>>
>>   #define SCOM_RESET_CMD         0x80000000
>>   #define SCOM_WRITE_CMD         0x80000000
>> @@ -156,7 +159,7 @@ static ssize_t scom_write(struct file *filep, const char __user *buf,
>>          if (rc)
>>                  dev_dbg(dev, "put_scom failed with:%d\n", rc);
>>
>> -       return rc;
>> +       return rc ? rc : len;
> This looks like an unrelated fix.

Yes, I guess a separate patch is in order.

>
>>   }
>>
>>   static loff_t scom_llseek(struct file *file, loff_t offset, int whence)
>> @@ -181,6 +184,48 @@ static const struct file_operations scom_fops = {
>>          .write  = scom_write,
>>   };
>>
>> +static int scom_reset_fsi2pib(struct fsi_device *fsi_dev)
>> +{
>> +       int rc;
>> +       u32 dummy = 0xFFFFFFFF;
>> +
>> +       rc = fsi_device_write(fsi_dev, SCOM_FSI2PIB_RESET_REG, &dummy,
>> +                             sizeof(u32));
>> +       if (rc)
>> +               dev_dbg(&fsi_dev->dev,
>> +                       "failed to write fsi2pib reset register rc:%d\n", rc);
> Is this expected behaviour? If not, use dev_err.
The rest of the driver uses dev_dbg even in error situations, so I tried 
to follow suit here.
>
>> +
>> +       return rc;
>> +}
>> +
>> +static int scom_full_reset(struct fsi_device *fsi_dev)
>> +{
>> +       int rc = 0;
>> +       u32 dummy = 0xFFFFFFFF;
>> +
>> +       rc = fsi_device_write(fsi_dev, SCOM_RESET_REG, &dummy, sizeof(u32));
> sizeof(dummy)
>
>> +       if (rc) {
>> +               dev_dbg(&fsi_dev->dev,
>> +                       "failed to write scom reset register rc:%d\n", rc);
>> +               return rc;
>> +       }
>> +
>> +       return scom_reset_fsi2pib(fsi_dev);
>> +}
>> +
>> +static ssize_t store_reset_register(struct device *dev,
>> +                                   struct device_attribute *attr,
>> +                                   const char *buf, size_t count)
>> +{
>> +       int rc;
>> +       struct fsi_device *fsi_dev = to_fsi_dev(dev);
>> +
>> +       rc = scom_full_reset(fsi_dev);
>> +
>> +       return rc ? rc : count;
>> +}
>> +DEVICE_ATTR(reset, 0200, NULL, store_reset_register);
>> +
>>   static int scom_probe(struct device *dev)
>>   {
>>          struct fsi_device *fsi_dev = to_fsi_dev(dev);
>> @@ -200,6 +245,8 @@ static int scom_probe(struct device *dev)
>>          scom->mdev.parent = dev;
>>          list_add(&scom->link, &scom_devices);
>>
>> +       device_create_file(dev, &dev_attr_reset);
>> +
> What is the expected behaviour if two different userspace programs
> have the reset and chardev open?

Probably a bus error or some sort of scom error if you write reset while 
you have a getscom/putscom operation going. Could add some locking?

Thanks,
Eddie

>
>>          return misc_register(&scom->mdev);
>>   }
>>
>> @@ -207,6 +254,8 @@ static int scom_remove(struct device *dev)
>>   {
>>          struct scom_device *scom, *scom_tmp;
>>          struct fsi_device *fsi_dev = to_fsi_dev(dev);
>> +
>> +       device_remove_file(dev, &dev_attr_reset);
>>
>>          list_for_each_entry_safe(scom, scom_tmp, &scom_devices, link) {
>>                  if (scom->fsi_dev == fsi_dev) {
>> --
>> 1.8.3.1
>>