[U-Boot] [PATCH 1/1] ARM: qemu-arm: enable RTC

[Heinrich Schuchardt]

On 07/03/2018 04:07 AM, Heinrich Schuchardt wrote:
> On 07/03/2018 01:51 AM, Takahiro AKASHI wrote:
>> On Mon, Jul 02, 2018 at 07:07:55PM +0300, Tuomas Tynkkynen wrote:
>>> Hi Heinrich,
>>>
>>> On 06/29/2018 01:34 AM, Heinrich Schuchardt wrote:
>>>> QEMU provides an emulated ARM AMBA PrimeCell PL031 RTC.
>>>>
>>>> The patch sets the base address in the board include file according to the
>>>> definition in hw/arm/virt.c of the QEMU source. It defines the Kconfig
>>>> option for the existing driver, and enables the RTC driver in
>>>> qemu_arm64_defconfig and qemu_arm_defconfig as well as the date command.
>>>>
>>>> We need an RTC to provide the GetTime() runtime service in the UEFI
>>>> subsystem.
>>>>
>>>> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
>>>> ---
>>>>  configs/qemu_arm64_defconfig | 2 ++
>>>>  configs/qemu_arm_defconfig   | 2 ++
>>>>  drivers/rtc/Kconfig          | 7 +++++++
>>>>  include/configs/qemu-arm.h   | 3 +++
>>>>  4 files changed, 14 insertions(+)
>>>>
>>>
>>> Reviewed-by: Tuomas Tynkkynen <tuomas.tynkkynen at iki.fi>
>>> Tested-by: Tuomas Tynkkynen <tuomas.tynkkynen at iki.fi>
>>>
>>> - Tuomas
>>
>> Well, it is a good time. Why not change the driver to driver model
>> like below:
>>  * I intentionally leave CONFIG_DM_RTC not mandatory here
>>  * The patch may be split into two parts; one for rtc, the other for qemu-arm
> 
> Hello Takahiro,
> 
> thank you for your suggestion. Yes we should convert drivers to the
> driver model. Unfortunately the patch that you appended below is not
> applicable to u-boot/master.
> 
> Error: patch failed: include/configs/qemu-arm.h:36
> error: include/configs/qemu-arm.h: patch does not apply
> Patch failed at 0001 ARM: qemu-arm: enable RTC
> 
> So I copied the changes to qemu-arm.h manually. Instead of defining the
> base address here it would be preferable to read the address from the
> device tree. This will become important if we get
> 
> Compiling with CONFIG_DM_RTC and CONFIG_RTC_PL031 resulted in warnings:
> 
>   CC      drivers/rtc/pl031.o
> drivers/rtc/pl031.c: In function ‘pl031_rtc_set’:
> drivers/rtc/pl031.c:141:17: warning: passing argument 1 of ‘rtc_set’
> discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
>   return rtc_set(tm);
>                  ^~
> drivers/rtc/pl031.c:72:5: note: expected ‘struct rtc_time *’ but
> argument is of type ‘const struct rtc_time *’
>  int rtc_set(struct rtc_time *tmp)
>      ^~~~~~~
> 
> I tested both with qemu-arm64_defconfig and qemu-arm_defconfig. The date
> command is running fine in both cases.
> 
> The driver with your patch cannot be compiled without DM_RTC (due to
> missing symbol CONFIG_SYS_RTC_PL031_BASE) so in Kconfig it should depend
> on DM_RTC.
> 
> There is no need to keep any old style stuff. I suggest to drop legacy
> functions and #ifdef CONFIG_DM_RTC. Also the following line can be removed:
> 
> scripts/config_whitelist.txt:4118:CONFIG_SYS_RTC_PL031_BASE
> 
> In qemu/hw/arm/virt.c, function create_rtc() a device tree node is
> created which describes the pl031 RTC including the base address. From
> what I read in the code the node should look like this:
> 
> /{
> 
> 	pl011 at 09010000 {
> 		compatible = "arm,pl011", "arm,primecell";
> 		#address-cells = <2>;
> 		#size-cells = <2>;
> 		reg = reg = <0x09010000 0x00001000>;
> 		...
> 	};
> 
> };

You can print the actual device tree within U-Boot using:

	fdt addr ${fdtcontroladdr}
	fdt print /

This is the relevant part of the output:

/ {
        interrupt-parent = <0x00008001>;
        #size-cells = <0x00000002>;
        #address-cells = <0x00000002>;
        compatible = "linux,dummy-virt";

        pl031 at 9010000 {
                clock-names = "apb_pclk";
                clocks = <0x00008000>;
                interrupts = <0x00000000 0x00000002 0x00000004>;
                reg = <0x00000000 0x09010000 0x00000000 0x00001000>;
                compatible = "arm,pl031", "arm,primecell";
        };

};

Regards

Heinrich