Re: [PATCH v9 3/7] i2c: fsi: Add port structures

[Eddie James <eajames@xxxxxxxxxxxxxxxxxx>]

On 06/04/2018 02:17 PM, Andy Shevchenko wrote:
> On Mon, Jun 4, 2018 at 10:00 PM, Eddie James <eajames@xxxxxxxxxxxxxxxxxx> wrote:
> > Add and initialize I2C adapters for each port on the FSI-attached I2C
> > master. Ports for each master are defined in the devicetree.
> >
> > Signed-off-by: Eddie James <eajames@xxxxxxxxxxxxxxxxxx>
> > ---
> >   drivers/i2c/busses/i2c-fsi.c | 90 ++++++++++++++++++++++++++++++++++++++++++++
> >   1 file changed, 90 insertions(+)
> >
> > diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
> > index e1b183c..12130c3 100644
> > --- a/drivers/i2c/busses/i2c-fsi.c
> > +++ b/drivers/i2c/busses/i2c-fsi.c
> > @@ -17,7 +17,10 @@
> >   #include <linux/fsi.h>
> >   #include <linux/i2c.h>
> >   #include <linux/kernel.h>
> > +#include <linux/list.h>
> >   #include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/slab.h>
> >
> >   #define FSI_ENGID_I2C          0x7
> >
> > @@ -123,6 +126,14 @@
> >   struct fsi_i2c_master {
> >          struct fsi_device       *fsi;
> >          u8                      fifo_size;
> > +       struct list_head        ports;
> > +};
> > +
> > +struct fsi_i2c_port {
> > +       struct list_head        list;
> > +       struct i2c_adapter      adapter;
> > +       struct fsi_i2c_master   *master;
> > +       u16                     port;
> >   };
> >
> >   static int fsi_i2c_read_reg(struct fsi_device *fsi, unsigned int reg,
> > @@ -176,9 +187,38 @@ static int fsi_i2c_dev_init(struct fsi_i2c_master *i2c)
> >          return fsi_i2c_write_reg(i2c->fsi, I2C_FSI_WATER_MARK, &watermark);
> >   }
> >
> > +static int fsi_i2c_set_port(struct fsi_i2c_port *port)
> > +{
> > +       int rc;
> > +       struct fsi_device *fsi = port->master->fsi;
> > +       u32 mode, dummy = 0;
> > +
> > +       rc = fsi_i2c_read_reg(fsi, I2C_FSI_MODE, &mode);
> > +       if (rc)
> > +               return rc;
> > +
> > +       if (FIELD_GET(I2C_MODE_PORT, mode) == port->port)
> > +               return 0;
> > +
> > +       mode = (mode & ~I2C_MODE_PORT) | FIELD_PREP(I2C_MODE_PORT, port->port);
> Did you consider to split this to two lines / assignments?

It fit on one line (< 80 chars) so I left it as-is...

> > +       rc = fsi_i2c_write_reg(fsi, I2C_FSI_MODE, &mode);
> > +       if (rc)
> > +               return rc;
> > +
> > +       /* reset engine when port is changed */
> > +       return fsi_i2c_write_reg(fsi, I2C_FSI_RESET_ERR, &dummy);
> > +}
> > +
> >   static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
> >                          int num)
> >   {
> > +       int rc;
> > +       struct fsi_i2c_port *port = adap->algo_data;
> > +
> > +       rc = fsi_i2c_set_port(port);
> > +       if (rc)
> > +               return rc;
> > +
> >          return -EOPNOTSUPP;
> >   }
> >
> > @@ -196,23 +236,72 @@ static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
> >   static int fsi_i2c_probe(struct device *dev)
> >   {
> >          struct fsi_i2c_master *i2c;
> > +       struct fsi_i2c_port *port;
> > +       struct device_node *np;
> >          int rc;
> > +       u32 port_no;
> >
> >          i2c = devm_kzalloc(dev, sizeof(*i2c), GFP_KERNEL);
> >          if (!i2c)
> >                  return -ENOMEM;
> >
> >          i2c->fsi = to_fsi_dev(dev);
> > +       INIT_LIST_HEAD(&i2c->ports);
> >
> >          rc = fsi_i2c_dev_init(i2c);
> >          if (rc)
> >                  return rc;
> >
> > +       /* Add adapter for each i2c port of the master. */
> > +       for_each_available_child_of_node(dev->of_node, np) {
> > +               rc = of_property_read_u32(np, "reg", &port_no);
> > +               if (rc || port_no > USHRT_MAX)
> > +                       continue;
>
>
> > +
> > +               port = kzalloc(sizeof(*port), GFP_KERNEL);
> > +               if (!port)
> > +                       break;
> > +
> > +               port->master = i2c;
> > +               port->port = port_no;
> > +
> > +               port->adapter.owner = THIS_MODULE;
> > +               port->adapter.dev.of_node = np;
> > +               port->adapter.dev.parent = dev;
> > +               port->adapter.algo = &fsi_i2c_algorithm;
> > +               port->adapter.algo_data = port;
> > +
> > +               snprintf(port->adapter.name, sizeof(port->adapter.name),
> > +                        "i2c_bus-%u", port_no);
> > +
> > +               rc = i2c_add_adapter(&port->adapter);
> > +               if (rc < 0) {
> > +                       dev_err(dev, "Failed to register adapter: %d\n", rc);
> > +                       kfree(port);
> > +                       continue;
> > +               }
> > +
> > +               list_add(&port->list, &i2c->ports);
> > +       }
> > +
> >          dev_set_drvdata(dev, i2c);
> >
> >          return 0;
> >   }
> >
> > +static int fsi_i2c_remove(struct device *dev)
> > +{
> > +       struct fsi_i2c_master *i2c = dev_get_drvdata(dev);
> > +       struct fsi_i2c_port *port;
> > +
> > +       list_for_each_entry(port, &i2c->ports, list) {
> > +               i2c_del_adapter(&port->adapter);
> > +               kfree(port);
> > +       }
> Just to be sure, it will be called if and only if all adapters are not
> busy. Correct?

If I understand the code and comments correctly, i2c_del_adapter will 
block until all references to the adapter device are gone. So, should be 
safe to free it now.

Thanks,
Eddie

> > +
> > +       return 0;
> > +}
> > +
> >   static const struct fsi_device_id fsi_i2c_ids[] = {
> >          { FSI_ENGID_I2C, FSI_VERSION_ANY },
> >          { 0 }
> > @@ -224,6 +313,7 @@ static int fsi_i2c_probe(struct device *dev)
> >                  .name = "i2c-fsi",
> >                  .bus = &fsi_bus_type,
> >                  .probe = fsi_i2c_probe,
> > +               .remove = fsi_i2c_remove,
> >          },
> >   };
> >
> > --
> > 1.8.3.1