| Message ID | 20211218214954.109755-3-colin.foster@in-advantage.com |
|---|---|
| State | New |
| Headers | show |
| Series | add support for VSC75XX control over SPI | expand |
On Sat, 18 Dec 2021, Colin Foster wrote: > Child devices need to get a regmap from a resource struct, specifically > from the MFD parent. The MFD parent has the interface to the hardware > layer, which could be I2C, SPI, PCIe, etc. > > This is somewhat a hack... ideally child devices would interface with the > struct device* directly, by way of a function like > devm_get_regmap_from_resource which would be akin to > devm_get_and_ioremap_resource. A less ideal option would be to interface > directly with MFD to get a regmap from the parent. > > This solution is even less ideal than both of the two suggestions, so is > intentionally left in a separate commit after the initial MFD addition. > > Signed-off-by: Colin Foster <colin.foster@in-advantage.com> > --- > drivers/mfd/ocelot-core.c | 9 +++++++++ > include/soc/mscc/ocelot.h | 12 ++++++++++++ > 2 files changed, 21 insertions(+) > > diff --git a/drivers/mfd/ocelot-core.c b/drivers/mfd/ocelot-core.c > index a65619a8190b..09132ea52760 100644 > --- a/drivers/mfd/ocelot-core.c > +++ b/drivers/mfd/ocelot-core.c > @@ -94,6 +94,15 @@ static struct regmap *ocelot_mfd_regmap_init(struct ocelot_mfd_core *core, > return regmap; > } > > +struct regmap *ocelot_mfd_get_regmap_from_resource(struct device *dev, > + const struct resource *res) > +{ > + struct ocelot_mfd_core *core = dev_get_drvdata(dev); > + > + return ocelot_mfd_regmap_init(core, res); > +} > +EXPORT_SYMBOL(ocelot_mfd_get_regmap_from_resource); This is almost certainly not the right way to do whatever it is you're trying to do! Please don't try to upstream "somewhat a hack"s into the Mainline kernel.
> > This is almost certainly not the right way to do whatever it is you're > > trying to do! > > > > Please don't try to upstream "somewhat a hack"s into the Mainline > > kernel. > > > > Please elaborate on the correct way to do that. What we have here is a > SoC (vsc7514) that has MMIO devices. This SoC has a MIPS CPU and > everything is fine when using it. However, the CPU can be disabled and > the SoC connected to another CPU using SPI or PCIe. What Colin is doing > here is using this SoC over SPI. Don't tell me this is not an MFD When did anyone say that? > because this is exactly what this is, a single chip with a collection of > devices that are also available separately. > > The various drivers for the VSC7514 have been written using regmap > exactly for this use case. The missing piece is probing the devices over > SPI instead of MMIO. > > Notice that all of that gets worse when using PCIe on architectures that > don't have device tree support and Clément will submit multiple series > trying to fix that. Okay, it sounds like I'm missing some information, let's see if we can get to the bottom of this so that I can provide some informed guidance. > On 29/12/2021 15:23:59+0000, Lee Jones wrote: > > On Sat, 18 Dec 2021, Colin Foster wrote: > > > > > Child devices need to get a regmap from a resource struct, > > > specifically from the MFD parent. Child devices usually fetch the Regmap from a pointer the parent provides. Usually via either 'driver_data' or 'platform_data'. However, we can't do that here because ... > > > The MFD parent has the interface to the hardware > > > layer, which could be I2C, SPI, PCIe, etc. > > > > > > This is somewhat a hack... ideally child devices would interface with the > > > struct device* directly, by way of a function like > > > devm_get_regmap_from_resource which would be akin to > > > devm_get_and_ioremap_resource. However, we can't do that here because ... > > > A less ideal option would be to interface > > > directly with MFD to get a regmap from the parent. > > > > > > This solution is even less ideal than both of the two suggestions, so is > > > intentionally left in a separate commit after the initial MFD addition. > > > > > > Signed-off-by: Colin Foster <colin.foster@in-advantage.com> > > > --- > > > drivers/mfd/ocelot-core.c | 9 +++++++++ > > > include/soc/mscc/ocelot.h | 12 ++++++++++++ > > > 2 files changed, 21 insertions(+) > > > > > > diff --git a/drivers/mfd/ocelot-core.c b/drivers/mfd/ocelot-core.c > > > index a65619a8190b..09132ea52760 100644 > > > --- a/drivers/mfd/ocelot-core.c > > > +++ b/drivers/mfd/ocelot-core.c > > > @@ -94,6 +94,15 @@ static struct regmap *ocelot_mfd_regmap_init(struct ocelot_mfd_core *core, > > > return regmap; > > > } > > > > > > +struct regmap *ocelot_mfd_get_regmap_from_resource(struct device *dev, > > > + const struct resource *res) > > > +{ > > > + struct ocelot_mfd_core *core = dev_get_drvdata(dev); > > > + > > > + return ocelot_mfd_regmap_init(core, res); > > > +} > > > +EXPORT_SYMBOL(ocelot_mfd_get_regmap_from_resource); > > >
diff --git a/drivers/mfd/ocelot-core.c b/drivers/mfd/ocelot-core.c index a65619a8190b..09132ea52760 100644 --- a/drivers/mfd/ocelot-core.c +++ b/drivers/mfd/ocelot-core.c @@ -94,6 +94,15 @@ static struct regmap *ocelot_mfd_regmap_init(struct ocelot_mfd_core *core, return regmap; } +struct regmap *ocelot_mfd_get_regmap_from_resource(struct device *dev, + const struct resource *res) +{ + struct ocelot_mfd_core *core = dev_get_drvdata(dev); + + return ocelot_mfd_regmap_init(core, res); +} +EXPORT_SYMBOL(ocelot_mfd_get_regmap_from_resource); + int ocelot_mfd_init(struct ocelot_mfd_config *config) { struct device *dev = config->dev; diff --git a/include/soc/mscc/ocelot.h b/include/soc/mscc/ocelot.h index 3e9454b00562..a641c9cc6f3f 100644 --- a/include/soc/mscc/ocelot.h +++ b/include/soc/mscc/ocelot.h @@ -968,4 +968,16 @@ ocelot_mrp_del_ring_role(struct ocelot *ocelot, int port, } #endif +#if IS_ENABLED(CONFIG_MFD_OCELOT_CORE) +struct regmap *ocelot_mfd_get_regmap_from_resource(struct device *dev, + const struct resource *res); +#else +static inline regmap * +ocelot_mfd_get_regmap_from_resource(struct device *dev, + const struct resource *res) +{ + return NULL; +} +#endif + #endif
Child devices need to get a regmap from a resource struct, specifically from the MFD parent. The MFD parent has the interface to the hardware layer, which could be I2C, SPI, PCIe, etc. This is somewhat a hack... ideally child devices would interface with the struct device* directly, by way of a function like devm_get_regmap_from_resource which would be akin to devm_get_and_ioremap_resource. A less ideal option would be to interface directly with MFD to get a regmap from the parent. This solution is even less ideal than both of the two suggestions, so is intentionally left in a separate commit after the initial MFD addition. Signed-off-by: Colin Foster <colin.foster@in-advantage.com> --- drivers/mfd/ocelot-core.c | 9 +++++++++ include/soc/mscc/ocelot.h | 12 ++++++++++++ 2 files changed, 21 insertions(+)