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

[Joel Stanley]

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.

>
> 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.

>  }
>
>  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.

> +
> +       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?

>         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
>