Hi Linus,
On Mon, Dec 16, 2013 at 10:48:06AM +0100, Linus Walleij wrote:
> On Mon, Dec 16, 2013 at 12:27 AM, Sebastian Reichel <sre@xxxxxxxxxx> wrote:
> > Add driver handling GPIO pins of Nokia modems. The
> > driver provides reset notifications, so that SSI
> > clients can subscribe to them easily.
> >
> > Signed-off-by: Sebastian Reichel <sre@xxxxxxxxxx>
>
> If the driver provides reset notifications, should it rather be
> in drivers/reset?
>
> I'm thinking of a generic GPIO reset driver with a generic
> notification mechanism, which seems to be what this is.
>
> I.e. it doesn't look device-specific at all, just like some
> generic glue code that could be useful to many such
> scenarios.
I like the idea.
Probably the remaining gpio exporting code can be converted into
some generic gpio-sysfs-export driver as well.
What do you think about the following?
/*
* driver, which provides generic reset notifications
*/
cmt_reset: reset-notifier {
compatible = "linux,reset-notification";
interrupts = <gpio>;
};
/*
* driver, which exports the specified gpios in sysfs with the
* supplied names. The device will be named according to the
* label
*/
cmt_gpios: gpio-sysfs-export {
compatible = "linux,gpio-sysfs-export";
label = "nokia-cmt";
gpios = <A>, <B>, ...;
gpio-names = "A", "B", ...;
};
> > +config NOKIA_CMT
> > + tristate "Enable CMT support"
> > + help
> > + If you say Y here, you will enable CMT support.
> > +
> > + If unsure, say Y, or else you will not be able to use the CMT.
>
> None of this explains what this driver actually does and what
> CMT means, so please rewrite this a bit to be more helpful.
> The way it is written it could as well say "enable FOO support".
I probably should have reviewed this better. This is the original
text from Nokia's driver.
> > +++ b/drivers/misc/nokia-cmt.c
> > @@ -0,0 +1,298 @@
> > +/*
> > + * CMT support.
>
> So CMT = ...?
CMT = Cellular Modem
> > +/**
> > + * struct cmt_device - CMT device data
> > + * @cmt_rst_ind_tasklet: Bottom half for CMT reset line events
> > + * @cmt_rst_ind_irq: IRQ number of the CMT reset line
> > + * @n_head: List of notifiers registered to get CMT events
> > + * @node: Link on the list of available CMTs
> > + * @device: Reference to the CMT platform device
> > + */
> > +struct cmt_device {
> > + struct tasklet_struct cmt_rst_ind_tasklet;
> > + unsigned int cmt_rst_ind_irq;
> > + struct atomic_notifier_head n_head;
> > + struct list_head node;
> > + struct device *device;
> > + struct cmt_gpio *gpios;
> > + int gpio_amount;
> > +};
>
> The kerneldoc and and the struct are not in sync. Look
> this over.
I will fix this in v5 (in case that its not removed completly).
> > +static LIST_HEAD(cmt_list); /* List of CMT devices */
> (...)
> > +struct cmt_device *cmt_get(const char *name)
> > +{
> > + struct cmt_device *p, *cmt = ERR_PTR(-ENODEV);
> > +
> > + list_for_each_entry(p, &cmt_list, node)
> > + if (strcmp(name, dev_name(p->device)) == 0) {
> > + cmt = p;
> > + break;
> > + }
> > +
> > + return cmt;
> > +}
> > +EXPORT_SYMBOL_GPL(cmt_get);
>
> Is this driver used on non-DT platforms, or can we skip this
> struct device * referencing altogether?
>
> I would feel better if this driver looked more like
> drivers/mfd/syscon.c
Will be removed in v5.
> > +static irqreturn_t cmt_rst_ind_isr(int irq, void *cmtdev)
> > +{
> > + struct cmt_device *cmt = (struct cmt_device *)cmtdev;
> > +
> > + tasklet_schedule(&cmt->cmt_rst_ind_tasklet);
> > +
> > + return IRQ_HANDLED;
> > +}
>
> Why are you using a tasklet rather than a work
> for this?
No particular reason. I just took this over from Nokia's code.
-- Sebastian
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