Hi Philipp,
On Thu, Jun 05, 2014 at 06:36:45PM +0200, Philipp Zabel wrote:
> > +#include <linux/platform_device.h>
>
> Is there a reason this is not actually implemented as platform device?
The node describing this driver is shared with a pin controller and a
clock driver. The pin controller is implemented as a platform device. I
don't think we can have two platform device drivers using the device
tree for the same node. Or I'm maybe missing something.
>
> > +#include <linux/reset-controller.h>
> > +#include <linux/slab.h>
> > +#include <linux/spinlock.h>
> > +#include <linux/types.h>
> > +
> > +#define BERLIN_RESET_REGISTER 0x104
>
> How many reset registers are there? (See below).
I don't have lots of information about this. For now only the one used
to reset the USB PHY but others may come later.
> > +
> > +static int berlin_reset_reset(struct reset_controller_dev *rcdev,
> > + unsigned long id)
> > +{
> > + struct berlin_reset_priv *priv = to_berlin_reset_priv(rcdev);
> > + unsigned long flags;
> > + int bank = id / BITS_PER_LONG;
> > + int offset = id % BITS_PER_LONG;
> > +
> > + spin_lock_irqsave(&priv->lock, flags);
> > +
> > + writel(BIT(offset), priv->base + bank * 4);
> > +
> > + spin_unlock_irqrestore(&priv->lock, flags);
>
> Since this is a single write into an apparently self-clearing
> register, I see no need for the spinlock here.
Sure.
>
> > + /* let the reset be effective */
> > + udelay(10);
> > +
> > + return 0;
> > +}
> > +
> > +static struct reset_control_ops berlin_reset_ops = {
> > + .reset = berlin_reset_reset,
> > +};
> > +
> > +static int __berlin_reset_init(struct device_node *np)
> > +{
> > + struct berlin_reset_priv *priv;
> > + struct resource res;
> > + resource_size_t size;
> > + int ret;
> > +
> > + priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> > + if (!priv)
> > + return -ENOMEM;
> > +
> > + ret = of_address_to_resource(np, 0, &res);
> > + if (ret)
> > + goto err;
> > +
> > + size = resource_size(&res);
> > +
> > + priv->base = ioremap(res.start, size);
> > + if (!priv->base) {
> > + ret = -ENOMEM;
> > + goto err;
> > + }
>
> A platform driver could use devm_kzalloc, platform_get_resource,
> and devm_ioremap_resource here.
>
> > + priv->base += BERLIN_RESET_REGISTER;
> > +
> > + priv->rcdev.owner = THIS_MODULE;
> > + priv->rcdev.nr_resets = size * 32;
>
> This doesn't seem right. The device tree patch shows that
> size = 0x400.
The reg property is shared between drivers using the common chip
controller node. I do not know how many registers are actually used
to reset.
We then could hardcode the size, with the registers actually used here?
Thanks for the review!
Antoine
--
Antoine Ténart, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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