Re: [PATCH v3 3/6] rtc: goldfish: Support platform data for non-DT probing

[Kuan-Wei Chiu <visitorckw@gmail.com>]

Hi Heinrich,

On Wed, Dec 31, 2025 at 01:12:45PM +0100, Heinrich Schuchardt wrote:
> On 12/30/25 17:01, Kuan-Wei Chiu wrote:
> > Currently, the Goldfish RTC driver exclusively relies on device tree
> > to retrieve the base address, failing immediately if dev_read_addr()
> > returns FDT_ADDR_T_NONE. This restriction prevents the driver from
> > being used on platforms that instantiate devices via U_BOOT_DRVINFO()
> > instead of device tree, such as the QEMU m68k virt machine.
> > 
> > Add support for platform data to address this limitation. Update the
> > probe function to fall back to retrieving the base address from
> > struct goldfish_rtc_plat if the device tree address is unavailable.
> > Introduce a new header file include/goldfish_rtc.h to define the
> > platform data structure.
> > 
> > Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
> > ---
> > Changes in v3:
> > - New patch.
> > 
> > It appears there is no specific maintainer listed for this driver?
> > 
> >   drivers/rtc/goldfish_rtc.c | 10 ++++++++--
> >   include/goldfish_rtc.h     | 15 +++++++++++++++
> >   2 files changed, 23 insertions(+), 2 deletions(-)
> >   create mode 100644 include/goldfish_rtc.h
> > 
> > diff --git a/drivers/rtc/goldfish_rtc.c b/drivers/rtc/goldfish_rtc.c
> > index e63a2766c76..900daabccb9 100644
> > --- a/drivers/rtc/goldfish_rtc.c
> > +++ b/drivers/rtc/goldfish_rtc.c
> > @@ -9,6 +9,7 @@
> >   #include <div64.h>
> >   #include <dm.h>
> > +#include <goldfish_rtc.h>
> >   #include <mapmem.h>
> >   #include <rtc.h>
> >   #include <linux/io.h>
> > @@ -77,11 +78,16 @@ static int goldfish_rtc_set(struct udevice *dev, const struct rtc_time *time)
> >   static int goldfish_rtc_probe(struct udevice *dev)
> >   {
> >   	struct goldfish_rtc *priv = dev_get_priv(dev);
> > +	struct goldfish_rtc_plat *plat;
> >   	fdt_addr_t addr;
> >   	addr = dev_read_addr(dev);
> > -	if (addr == FDT_ADDR_T_NONE)
> > -		return -EINVAL;
> > +	if (addr == FDT_ADDR_T_NONE) {
> > +		plat = dev_get_plat(dev);
> > +		if (!plat)
> > +			return -EINVAL;
> > +		addr = (fdt_addr_t)plat->base;
> 
> addr is not a pointer, it is an address in the sandbox virtual memory
> address space. This is why map_sysmem() is used below.
> 
> The suggested code fails to build on sandbox_defconfig with the driver
> enabled:
> 
> drivers/rtc/goldfish_rtc.c: In function ‘goldfish_rtc_probe’:
> drivers/rtc/goldfish_rtc.c:89:24: warning: cast from pointer to integer of
> different size [-Wpointer-to-int-cast]
>    89 |                 addr = (fdt_addr_t)plat->base;
>       |
> 
> Please, use
> 
> 	priv->base = plat->base;
> 
> If plat->base is NULL, please, throw -EINVAL.

My apologies for the oversight.
I agree with your suggestion.

I will update the code to assign plat->base directly to priv->base in
the next version. I will also verify the build with sandbox_defconfig
to ensure there are no issues.

Regards,
Kuan-Wei