Re: [Qemu-devel] [PATCH v2 2/2] hw/arm/virt: Provide PL031 RTC

[Peter Crosthwaite]

On Thu, Jun 12, 2014 at 2:01 AM, Claudio Fontana
<address@hidden> wrote:
> On 10.06.2014 19:06, Peter Maydell wrote:
>> UEFI mandates that the platform must include an RTC, so provide
>> one in 'virt', using the PL031.
>>
>> Signed-off-by: Peter Maydell <address@hidden>
>> ---
>>  hw/arm/virt.c | 30 ++++++++++++++++++++++++++++++
>>  1 file changed, 30 insertions(+)
>>
>> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
>> index e658eb0..b60928e 100644
>> --- a/hw/arm/virt.c
>> +++ b/hw/arm/virt.c
>> @@ -66,6 +66,7 @@ enum {
>>      VIRT_GIC_CPU,
>>      VIRT_UART,
>>      VIRT_MMIO,
>> +    VIRT_RTC,
>>  };
>>
>>  typedef struct MemMapEntry {
>> @@ -93,6 +94,8 @@ typedef struct VirtBoardInfo {
>>   * high memory region beyond 4GB).
>>   * This represents a compromise between how much RAM can be given to
>>   * a 32 bit VM and leaving space for expansion and in particular for PCI.
>> + * Note that devices should generally be placed at multiples of 0x10000,
>> + * to accommodate guests using 64K pages.
>>   */
>>  static const MemMapEntry a15memmap[] = {
>>      [VIRT_FLASH] = { 0, 0x8000000 },
>> @@ -101,6 +104,7 @@ static const MemMapEntry a15memmap[] = {
>>      [VIRT_GIC_DIST] = { 0x8000000, 0x10000 },
>>      [VIRT_GIC_CPU] = { 0x8010000, 0x10000 },
>>      [VIRT_UART] = { 0x9000000, 0x1000 },
>> +    [VIRT_RTC] = { 0x90010000, 0x1000 },
>>      [VIRT_MMIO] = { 0xa000000, 0x200 },
>>      /* ...repeating for a total of NUM_VIRTIO_TRANSPORTS, each of that size 
>> */
>>      /* 0x10000000 .. 0x40000000 reserved for PCI */
>> @@ -109,6 +113,7 @@ static const MemMapEntry a15memmap[] = {
>>
>>  static const int a15irqmap[] = {
>>      [VIRT_UART] = 1,
>> +    [VIRT_RTC] = 2,
>>      [VIRT_MMIO] = 16, /* ...to 16 + NUM_VIRTIO_TRANSPORTS - 1 */
>>  };
>>
>> @@ -340,6 +345,29 @@ static void create_uart(const VirtBoardInfo *vbi, 
>> qemu_irq *pic)
>>      g_free(nodename);
>>  }
>>
>> +static void create_rtc(const VirtBoardInfo *vbi, qemu_irq *pic)
>> +{
>> +    char *nodename;
>> +    hwaddr base = vbi->memmap[VIRT_RTC].base;
>> +    hwaddr size = vbi->memmap[VIRT_RTC].size;
>> +    int irq = vbi->irqmap[VIRT_RTC];
>> +    const char compat[] = "arm,pl031\0arm,primecell";
>> +
>> +    sysbus_create_simple("pl031", base, pic[irq]);
>> +
>> +    nodename = g_strdup_printf("/address@hidden" PRIx64, base);
>> +    qemu_fdt_add_subnode(vbi->fdt, nodename);
>> +    qemu_fdt_setprop(vbi->fdt, nodename, "compatible", compat, 
>> sizeof(compat));
>> +    qemu_fdt_setprop_sized_cells(vbi->fdt, nodename, "reg",
>> +                                 2, base, 2, size);
>> +    qemu_fdt_setprop_cells(vbi->fdt, nodename, "interrupts",
>> +                           GIC_FDT_IRQ_TYPE_SPI, irq,
>> +                           GIC_FDT_IRQ_FLAGS_EDGE_LO_HI);
>> +    qemu_fdt_setprop_cell(vbi->fdt, nodename, "clocks", vbi->clock_phandle);
>> +    qemu_fdt_setprop_string(vbi->fdt, nodename, "clock-names", "apb_pclk");
>> +    g_free(nodename);
>> +}
>> +
>>  static void create_virtio_devices(const VirtBoardInfo *vbi, qemu_irq *pic)
>>  {
>>      int i;
>> @@ -524,6 +552,8 @@ static void machvirt_init(MachineState *machine)
>>
>>      create_uart(vbi, pic);
>>
>> +    create_rtc(vbi, pic);
>> +
>>      /* Create mmio transports, so the user can create virtio backends
>>       * (which will be automatically plugged in to the transports). If
>>       * no backend is created the transport will just sit harmlessly idle.
>>
>
> I am quite happy with the RTC device being added to the virt platform, as 
> this will move me from 1970 in the guest, where I am at the moment. :)
>
> One question I would have is, what would be the best/recommended way as a 
> user of the virt platform
> to add buses and devices to the platform? Is using virt as the base platform, 
> and extending it with additional buses and devices a sensible thing to do?
>

Yes.

> In my case I am particularly interested in the possibility to add a PCI-E bus 
> to the platform in some (any) way, so that QEMU provides support for that, 
> one that does not mean maintaining a separate patchset. Is extending via 
> --device a viable option?
> New machine model?

For PCI support it should just be a case of adding a PCI controller to
the virt board, then -device should just work for pci devs.

Regards,
Peter

>
> Thank you for any advice,
>
> Claudio
>
>