Hi Peter, > -----Original Message----- > From: Peter Rosin [mailto:p...@axentia.se] > Sent: Monday, 25 February, 2019 08:14 PM > To: Pankaj Bansal <pankaj.ban...@nxp.com>; Leo Li <leoyang...@nxp.com> > Cc: linux-kernel@vger.kernel.org > Subject: Re: [PATCH v3 2/2] drivers: mux: Add Generic regmap bitfield-based > multiplexer in mmio-mux > > On 2019-02-24 09:27, Pankaj Bansal wrote: > > Generic register bitfield-based multiplexer that controls the > > multiplexer producer defined under a parent node. > > The driver corresponding to parent node provides register read/write > > capabilities. > > > > Signed-off-by: Pankaj Bansal <pankaj.ban...@nxp.com> > > --- > > > > Notes: > > V3: > > - Added the patch in series with device tree binding patch > > - Added the NULL return handling for regmap > > V2: > > - removed seperate driver regmap.c and added the regmap function in > mmio.c > > based on compatible field, the syscon or regmap function would be > > called > > - Modified the KConfig as per Peter's comments > > > > drivers/mux/Kconfig | 12 ++++++------ drivers/mux/mmio.c | 10 > > +++++++--- > > 2 files changed, 13 insertions(+), 9 deletions(-) > > > > diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig index > > 7659d6c5f718..e5c571fd232c 100644 > > --- a/drivers/mux/Kconfig > > +++ b/drivers/mux/Kconfig > > @@ -46,14 +46,14 @@ config MUX_GPIO > > be called mux-gpio. > > > > config MUX_MMIO > > - tristate "MMIO register bitfield-controlled Multiplexer" > > - depends on (OF && MFD_SYSCON) || COMPILE_TEST > > + tristate "MMIO/Regmap register bitfield-controlled Multiplexer" > > + depends on OF || COMPILE_TEST > > help > > - MMIO register bitfield-controlled Multiplexer controller. > > + MMIO/Regmap register bitfield-controlled Multiplexer controller. > > > > - The driver builds multiplexer controllers for bitfields in a syscon > > - register. For N bit wide bitfields, there will be 2^N possible > > - multiplexer states. > > + The driver builds multiplexer controllers for bitfields in either > > + a syscon register or a driver regmap register. For N bit wide > > + bitfields, there will be 2^N possible multiplexer states. > > > > To compile the driver as a module, choose M here: the module will > > be called mux-mmio. > > diff --git a/drivers/mux/mmio.c b/drivers/mux/mmio.c index > > 935ac44aa209..cc02155e4644 100644 > > --- a/drivers/mux/mmio.c > > +++ b/drivers/mux/mmio.c > > @@ -28,6 +28,7 @@ static const struct mux_control_ops mux_mmio_ops = { > > > > static const struct of_device_id mux_mmio_dt_ids[] = { > > { .compatible = "mmio-mux", }, > > + { .compatible = "reg-mux", }, > > { /* sentinel */ } > > }; > > MODULE_DEVICE_TABLE(of, mux_mmio_dt_ids); @@ -43,9 +44,12 @@ > static > > int mux_mmio_probe(struct platform_device *pdev) > > int ret; > > int i; > > > > - regmap = syscon_node_to_regmap(np->parent); > > - if (IS_ERR(regmap)) { > > - ret = PTR_ERR(regmap); > > + if (of_device_is_compatible(np, "mmio-mux")) > > + regmap = syscon_node_to_regmap(np->parent); > > + else > > + regmap = dev_get_regmap(dev->parent, NULL); > > + if (IS_ERR_OR_NULL(regmap)) { > > + ret = PTR_ERR_OR_ZERO(regmap) ? PTR_ERR(regmap) : - > ENODEV; > > The above is not correct, this should be better (untested): > > ret = PTR_ERR(regmap) ?: -ENODEV;
Omitting the second operand in ternary operator is not standard. https://stackoverflow.com/questions/34559705/ternary-operator-without-the-middle-expression Although, it *has been* used in kernel in many places https://livegrep.com/search/linux?q=file%3A%5C.c%24%20%5C%3F%5C%3A&fold_case=auto®ex=true&context=true > > Cheers, > Peter > > > dev_err(dev, "failed to get regmap: %d\n", ret); > > return ret; > > } > >
