| Message ID | 32edfd70-95dc-26a1-2ea6-143344cb2384@linux.intel.com |
|---|---|
| State | New |
| Headers | show |
| Series | RFC: gpio: mmio: add support for 3 direction regs | expand |
Hi Ramon, On 01/03/2019 09:36 AM, Fried, Ramon wrote: > Hi. > > I'm working on a driver for STA2X11 GPIO controller who seems to fit > best to the generic mmio driver, I hope you have seen the existing driver drivers/gpio/gpio-sta2x11.c > the only problem I have is with the dir register case. The STA2X11 > has 3 registers for dir, one for data, one for set and one for > clear. The generic-mmio driver has support for this fashion for the > dat & set & clear registers but not for dirout/dirin registers. > > I wonder if support for this is generic enough to deserve a patch, if > so I'm willing to quickly add this support, if not, adding a flag > such as below, will allow partly using the generic mmio driver only > for set/get and the direction can be handled outside the driver. > If gpio-mmio fits well, then it might be simpler to set a flag BGPIOF_UNREADABLE_REG_DIR, then call bgpio_init() and then overwrite .direction_input, .direction_output and .get_direction callbacks, as a reference you can take a look at gpio-74xx-mmio.c -- Best wishes, Vladimir
On 1/3/2019 10:07, Vladimir Zapolskiy wrote: > Hi Ramon, > > On 01/03/2019 09:36 AM, Fried, Ramon wrote: >> Hi. >> >> I'm working on a driver for STA2X11 GPIO controller who seems to fit >> best to the generic mmio driver, > I hope you have seen the existing driver drivers/gpio/gpio-sta2x11.c I surely did. we have the same IP in our soc but it was changed a lot internally, don't want to litter the original. > >> the only problem I have is with the dir register case. The STA2X11 >> has 3 registers for dir, one for data, one for set and one for >> clear. The generic-mmio driver has support for this fashion for the >> dat & set & clear registers but not for dirout/dirin registers. >> >> I wonder if support for this is generic enough to deserve a patch, if >> so I'm willing to quickly add this support, if not, adding a flag >> such as below, will allow partly using the generic mmio driver only >> for set/get and the direction can be handled outside the driver. >> > If gpio-mmio fits well, then it might be simpler to set a flag > BGPIOF_UNREADABLE_REG_DIR, then call bgpio_init() and then overwrite > .direction_input, .direction_output and .get_direction callbacks, > as a reference you can take a look at gpio-74xx-mmio.c Nice. That's an option I didn't think of, better than setting the flag. what about adding the generic support ? > > -- > Best wishes, > Vladimir
On 01/03/2019 10:51 AM, Fried, Ramon wrote: > > On 1/3/2019 10:07, Vladimir Zapolskiy wrote: >> Hi Ramon, >> >> On 01/03/2019 09:36 AM, Fried, Ramon wrote: >>> Hi. >>> >>> I'm working on a driver for STA2X11 GPIO controller who seems to fit >>> best to the generic mmio driver, >> I hope you have seen the existing driver drivers/gpio/gpio-sta2x11.c > I surely did. we have the same IP in our soc but it was changed a lot > internally, don't want to litter the original. >> >>> the only problem I have is with the dir register case. The STA2X11 >>> has 3 registers for dir, one for data, one for set and one for >>> clear. The generic-mmio driver has support for this fashion for the >>> dat & set & clear registers but not for dirout/dirin registers. >>> >>> I wonder if support for this is generic enough to deserve a patch, if >>> so I'm willing to quickly add this support, if not, adding a flag >>> such as below, will allow partly using the generic mmio driver only >>> for set/get and the direction can be handled outside the driver. >>> >> If gpio-mmio fits well, then it might be simpler to set a flag >> BGPIOF_UNREADABLE_REG_DIR, then call bgpio_init() and then overwrite >> .direction_input, .direction_output and .get_direction callbacks, >> as a reference you can take a look at gpio-74xx-mmio.c > > Nice. > That's an option I didn't think of, better than setting the flag. > what about adding the generic support ? Setting a GPIO direction over three different registers doesn't sound as a suitable candidate for generalization, also your particular implementation is partial, relies on external platform/driver code to preset the directions and it does not allow to change direction in runtime, so just renounce the idea. -- Best wishes, Vladimir
On 1/3/2019 10:59, Vladimir Zapolskiy wrote: > On 01/03/2019 10:51 AM, Fried, Ramon wrote: >> On 1/3/2019 10:07, Vladimir Zapolskiy wrote: >>> Hi Ramon, >>> >>> On 01/03/2019 09:36 AM, Fried, Ramon wrote: >>>> Hi. >>>> >>>> I'm working on a driver for STA2X11 GPIO controller who seems to fit >>>> best to the generic mmio driver, >>> I hope you have seen the existing driver drivers/gpio/gpio-sta2x11.c >> I surely did. we have the same IP in our soc but it was changed a lot >> internally, don't want to litter the original. >>>> the only problem I have is with the dir register case. The STA2X11 >>>> has 3 registers for dir, one for data, one for set and one for >>>> clear. The generic-mmio driver has support for this fashion for the >>>> dat & set & clear registers but not for dirout/dirin registers. >>>> >>>> I wonder if support for this is generic enough to deserve a patch, if >>>> so I'm willing to quickly add this support, if not, adding a flag >>>> such as below, will allow partly using the generic mmio driver only >>>> for set/get and the direction can be handled outside the driver. >>>> >>> If gpio-mmio fits well, then it might be simpler to set a flag >>> BGPIOF_UNREADABLE_REG_DIR, then call bgpio_init() and then overwrite >>> .direction_input, .direction_output and .get_direction callbacks, >>> as a reference you can take a look at gpio-74xx-mmio.c >> Nice. >> That's an option I didn't think of, better than setting the flag. >> what about adding the generic support ? > Setting a GPIO direction over three different registers doesn't sound > as a suitable candidate for generalization, also your particular > implementation is partial, relies on external platform/driver code > to preset the directions and it does not allow to change direction > in runtime, so just renounce the idea. Alrighty then, will overwrite the direction CBs. Thanks. > > -- > Best wishes, > Vladimir
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h index a4d5eb3..4f91526 100644 --- a/include/linux/gpio/driver.h +++ b/include/linux/gpio/driver.h @@ -435,6 +435,7 @@ int bgpio_init(struct gpio_chip *gc, struct device *dev, #define BGPIOF_BIG_ENDIAN_BYTE_ORDER BIT(3) #define BGPIOF_READ_OUTPUT_REG_SET BIT(4) /* reg_set stores output value */ #define BGPIOF_NO_OUTPUT BIT(5) /* only input */ +#define BGPIOF_NO_DIRECTION BIT(6) #endif diff --git a/drivers/gpio/gpio-mmio.c b/drivers/gpio/gpio-mmio.c index 935292a..66f6448 100644 --- a/drivers/gpio/gpio-mmio.c +++ b/drivers/gpio/gpio-mmio.c @@ -554,6 +554,8 @@ static int bgpio_setup_direction(struct gpio_chip *gc, gc->direction_input = bgpio_dir_in; gc->get_direction = bgpio_get_dir; gc->bgpio_dir_inverted = true; + } else if (flags & BGPIOF_NO_DIRECTION) { + return 0; } else { if (flags & BGPIOF_NO_OUTPUT) gc->direction_output = bgpio_dir_out_err; @@ -638,7 +640,7 @@ int bgpio_init(struct gpio_chip *gc, struct device *dev, if (gc->set == bgpio_set_set && !(flags & BGPIOF_UNREADABLE_REG_SET)) gc->bgpio_data = gc->read_reg(gc->reg_set); - if (gc->reg_dir && !(flags & BGPIOF_UNREADABLE_REG_DIR)) + if (gc->reg_dir && !(flags & (BGPIOF_UNREADABLE_REG_DIR | BGPIOF_NO_DIRECTION))) gc->bgpio_dir = gc->read_reg(gc->reg_dir); return ret;