On Wed, Jun 18, 2008 at 08:00:08PM +0100, Ben Dooks wrote:
> > +static int i2c_virt_master_xfer(struct i2c_adapter *adap,
> > + struct i2c_msg msgs[], int num)
> > +{
> > + struct i2c_virt_priv *priv = adap->algo_data;
> > + struct i2c_adapter *parent = priv->parent_adap;
> > + int ret;
> > +
> > + /* Grab the lock for the parent adapter. We already hold the lock for
> > + * the virtual adapter. Then select the right mux port and perform
> > + * the transfer.
> > + */
> > +
> > + mutex_lock(&parent->bus_lock);
> > +
> > + ret = priv->select(parent, priv->client, priv->id);
> > + if (ret >= 0)
> > + ret = parent->algo->master_xfer(parent, msgs, num);
> > + priv->deselect(parent, priv->client, priv->id);
> > +
> > + mutex_unlock(&parent->bus_lock);
> > +
> > + return ret;
> > +}
>
> Out of interest, is it going to be better to hide the parent
> away completely from the system? I suppose if clients have
> already bound to it then we're probably going to just have to
> live with it being available.
I'm sorry but I don't understand what you mean. =:-o
The parent is strictly connected with the children virtual adapter, how
can I hide it?
> > +struct i2c_adapter *i2c_add_virt_adapter(struct i2c_adapter *parent,
> > + struct i2c_client *client,
> > + u32 force_nr, u32 mux_val,
> > + int (*select_cb) (struct i2c_adapter *,
> > + struct i2c_client *, u32),
> > + int (*deselect_cb) (struct i2c_adapter *,
> > + struct i2c_client *, u32))
> > +{
> > + struct i2c_adapter *adap;
> > + struct i2c_virt_priv *priv;
> > + struct i2c_algorithm *algo;
> > + int ret;
> > +
> > + adap = kzalloc(sizeof(struct i2c_adapter)
> > + + sizeof(struct i2c_virt_priv)
> > + + sizeof(struct i2c_algorithm), GFP_KERNEL);
> > + if (!adap)
> > + return NULL;
> > +
> > + priv = (struct i2c_virt_priv *)(adap + 1);
> > + algo = (struct i2c_algorithm *)(priv + 1);
>
> you shouldn't need force-typecast here.
>
> you could always make your i2c_virt_priv data contain the i2c_adapter
> and i2c_algorithm structure so you can easily go between them.
Ok.
> > + /* Set up private adapter data */
> > + priv->parent_adap = parent;
> > + priv->client = client;
> > + priv->id = mux_val;
> > + priv->select = select_cb;
> > + priv->deselect = deselect_cb;
> > +
> > + /* Need to do algo dynamically because we don't know ahead
> > + * of time what sort of physical adapter we'll be dealing with.
> > + */
> > + algo->master_xfer = (parent->algo->master_xfer
> > + ? i2c_virt_master_xfer : NULL);
> > + algo->smbus_xfer = (parent->algo->smbus_xfer
> > + ? i2c_virt_smbus_xfer : NULL);
> > + algo->functionality = i2c_virt_functionality;
>
> you're using kzalloc, so this boils down to the neater:
>
> if (parent->algo->master_xfer)
> algo->master_xfer = i2c_virt_master_xfer;
> etc.
Ok.
> > + /* Now fill out new adapter structure */
> > + snprintf(adap->name, sizeof(adap->name),
> > + "i2c-%d-virt (mux %02x:%02x)",
> > + i2c_adapter_id(parent), client->addr, mux_val);
> > + adap->id = I2C_HW_VIRT | i2c_adapter_id(parent);
> > + adap->algo = algo;
> > + adap->algo_data = priv;
> > + adap->timeout = VIRT_TIMEOUT;
> > + adap->retries = VIRT_RETRIES;
> > + adap->dev.parent = &parent->dev;
>
> How about creating a struct with the callbacks in, and the data
> for timeout, retries and any other data that would be needed?
There are few assignments... :)
> > + if (force_nr) {
> > + adap->nr = force_nr;
> > + ret = i2c_add_numbered_adapter(adap);
> > + } else
> > + ret = i2c_add_adapter(adap);
> > + if (ret < 0) {
> > + kfree(adap);
> > + return NULL;
> > + }
> > +
> > + dev_info(&parent->dev, "i2c-virt-%d: Virtual I2C bus - "
> > + "physical bus i2c-%d, multiplexer 0x%02x port %d\n",
> > + i2c_adapter_id(adap), i2c_adapter_id(parent),
> > + client->addr, mux_val);
> > +
> > + return adap;
> > +}
> > +EXPORT_SYMBOL_GPL(i2c_add_virt_adapter);
> > +
> > +int i2c_del_virt_adapter(struct i2c_adapter *adap)
> > +{
> > + int ret;
> > +
> > + ret = i2c_del_adapter(adap);
> > + if (ret < 0)
> > + return ret;
> > + kfree(adap);
> > +
> > + return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(i2c_del_virt_adapter);
> > +
> > +MODULE_AUTHOR("Rodolfo Giometti <giometti at linux.it, " \
> > + "Kumar Gala <galak at kernel.crashing.org>");
> > +MODULE_DESCRIPTION("Virtual I2C driver for multiplexed I2C busses");
> > +MODULE_LICENSE("GPL");
>
> "GPL v2" is the definition you probably want here.
Ok.
Ciao,
Rodolfo
--
GNU/Linux Solutions e-mail: giometti at enneenne.com
Linux Device Driver giometti at linux.it
Embedded Systems phone: +39 349 2432127
UNIX programming skype: rodolfo.giometti
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