Re: [PATCH v4 3/5] mfd: Add RTL8231 core device

Sander Vanheule
2021-06-05T11:07:51Z

On Thu, 2021-06-03 at 13:58 +0300, Andy Shevchenko wrote:
> On Thu, Jun 3, 2021 at 1:01 PM Sander Vanheule <sander@svanheule.net> wrote:
> > +static int rtl8231_reg_read(void *context, unsigned int reg, unsigned int
> > *val)
> > +{
> > +       struct mdio_device *mdio_dev = context;
> > +       int ret;
> > +
> > +       ret = mdiobus_read(mdio_dev->bus, mdio_dev->addr,
> > RTL8231_REAL_REG(reg));
> > +
> > +       if (ret < 0)
> > +               return ret;
> > +
> > +       *val = ret & 0xffff;
> > +
> > +       return 0;
> > +}
> > +
> > +static int rtl8231_reg_write(void *context, unsigned int reg, unsigned int
> > val)
> > +{
> > +       struct mdio_device *mdio_dev = context;
> > +
> > +       return mdiobus_write(mdio_dev->bus, mdio_dev->addr,
> > RTL8231_REAL_REG(reg), val);
> > +}
>
> Hmm... Maybe we can amend regmap-mdio to avoid duplication of the
> above? Something like xlate in gpio-regmap or so?

(+Cc Mark for the regmap discussion)

It turns out that I can't use both devm_regmap_init_mdio and the overrides
regmap_config.reg_read/write. This appears to be in contrast to what the
documentation for these two overrides suggest. devm_regmap_init_mdio provides a
bus for the regmap, which causes the overrides to be ignored in regmap.c

Then I tried to use the paging support provided by regmap, by adding the
following config:

static struct regmap_range_cfg rtl8231_reg_ranges[] = {
{
/* Specify an unused register with an empty mask */
.selector_reg = 0x1f,
.selector_mask = 0x00,
.selector_shift = 0,
.range_min = 0x00,
.range_max = RTL8231_VREG(RTL8231_REG_COUNT - 1),
.window_start = 0x00,
.window_len = 0x20,
},
};

This also doesn't work, because the used _regmap_bus_reg_read/write don't
resolve register pages. The patch below fixes this, but maybe this missing
functionality is intentional, and I should actually implement
regmap_bus.read/write?

----8<----
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 0d185ec018a5..20b6a2e0d2e3 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -1881,6 +1881,15 @@ static int _regmap_bus_reg_write(void *context, unsigned
int reg,
unsigned int val)
{
struct regmap *map = context;
+ struct regmap_range_node *range;
+ int ret;
+
+ range = _regmap_range_lookup(map, reg);
+ if (range) {
+ ret = _regmap_select_page(map, &reg, range, 1);
+ if (ret != 0)
+ return ret;
+ }

return map->bus->reg_write(map->bus_context, reg, val);
}
@@ -2651,6 +2660,15 @@ static int _regmap_bus_reg_read(void *context, unsigned
int reg,
unsigned int *val)
{
struct regmap *map = context;
+ struct regmap_range_node *range;
+ int ret;
+
+ range = _regmap_range_lookup(map, reg);
+ if (range) {
+ ret = _regmap_select_page(map, &reg, range, 1);
+ if (ret != 0)
+ return ret;
+ }

return map->bus->reg_read(map->bus_context, reg, val);
}

--
Best,
Sander