Re: [Qemu-devel] [PATCH v2 2/8] ppc/pnv: enable only one LPC bus

[David Gibson <david@gibson.dropbear.id.au>]

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On Mon, Apr 10, 2017 at 03:56:52PM +0200, Cédric Le Goater wrote:
> The firmware (skiboot) chooses the default LPC bus of a multichip
> systems using a "primary" property. The LPC bus of chip 0 should be
> the only connected in the system. Let's advertise it in the device
> tree.
> 
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
>  Changes since v1:
> 
>  - the device tree is populated for all LPC busses of the system but
>    only the one on chip 0 has the "primary" property.
> 
>  hw/ppc/pnv.c             |  2 ++
>  hw/ppc/pnv_lpc.c         | 23 ++++++++++++++---------
>  include/hw/ppc/pnv_lpc.h |  2 ++
>  3 files changed, 18 insertions(+), 9 deletions(-)
> 
> diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
> index 27589b91d1cf..7d742b6e34e1 100644
> --- a/hw/ppc/pnv.c
> +++ b/hw/ppc/pnv.c
> @@ -765,6 +765,8 @@ static void pnv_chip_realize(DeviceState *dev, Error **errp)
>      g_free(typename);
>  
>      /* Create LPC controller */
> +    object_property_set_int(OBJECT(&chip->lpc), chip->chip_id, "chip-id",
> +                            &error_fatal);
>      object_property_set_bool(OBJECT(&chip->lpc), true, "realized",
>                               &error_fatal);
>      pnv_xscom_add_subregion(chip, PNV_XSCOM_LPC_BASE, &chip->lpc.xscom_regs);
> diff --git a/hw/ppc/pnv_lpc.c b/hw/ppc/pnv_lpc.c
> index baee366d386a..13d7a695678d 100644
> --- a/hw/ppc/pnv_lpc.c
> +++ b/hw/ppc/pnv_lpc.c
> @@ -92,14 +92,6 @@ enum {
>  #define LPC_HC_REGS_OPB_SIZE    0x00001000
>  
>  
> -/*
> - * TODO: the "primary" cell should only be added on chip 0. This is
> - * how skiboot chooses the default LPC controller on multichip
> - * systems.
> - *
> - * It would be easly done if we can change the populate() interface to
> - * replace the PnvXScomInterface parameter by a PnvChip one
> - */
>  static int pnv_lpc_populate(PnvXScomInterface *dev, void *fdt, int xscom_offset)
>  {
>      const char compat[] = "ibm,power8-lpc\0ibm,lpc";
> @@ -110,6 +102,7 @@ static int pnv_lpc_populate(PnvXScomInterface *dev, void *fdt, int xscom_offset)
>          cpu_to_be32(lpc_pcba),
>          cpu_to_be32(PNV_XSCOM_LPC_SIZE)
>      };
> +    PnvLpcController *lpc = PNV_LPC(dev);
>  
>      name = g_strdup_printf("isa@%x", lpc_pcba);
>      offset = fdt_add_subnode(fdt, xscom_offset, name);
> @@ -119,7 +112,13 @@ static int pnv_lpc_populate(PnvXScomInterface *dev, void *fdt, int xscom_offset)
>      _FDT((fdt_setprop(fdt, offset, "reg", reg, sizeof(reg))));
>      _FDT((fdt_setprop_cell(fdt, offset, "#address-cells", 2)));
>      _FDT((fdt_setprop_cell(fdt, offset, "#size-cells", 1)));
> -    _FDT((fdt_setprop(fdt, offset, "primary", NULL, 0)));
> +
> +    /* The firmware (skiboot) chooses the default LPC bus of the
> +     * system using a "primary" property.
> +     */
> +    if (lpc->chip_id == 0x0) {
> +        _FDT((fdt_setprop(fdt, offset, "primary", NULL, 0)));
> +    }

So, the choice of primary bus is really a machine level thing, rather
than chip level.

So I think it would make more sense for the machine to poke the
'primary' property into the device tree afterwards, rather than adding
it initially within the chip/LPC code.  That will then avoid having to
pass the chip-id property into the LPC.

>      _FDT((fdt_setprop(fdt, offset, "compatible", compat, sizeof(compat))));
>      return 0;
>  }
> @@ -486,6 +485,11 @@ static void pnv_lpc_realize(DeviceState *dev, Error **errp)
>      lpc->psi = PNV_PSI(obj);
>  }
>  
> +static Property pnv_lpc_properties[] = {
> +    DEFINE_PROP_UINT32("chip-id", PnvLpcController, chip_id, 0),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
>  static void pnv_lpc_class_init(ObjectClass *klass, void *data)
>  {
>      DeviceClass *dc = DEVICE_CLASS(klass);
> @@ -494,6 +498,7 @@ static void pnv_lpc_class_init(ObjectClass *klass, void *data)
>      xdc->populate = pnv_lpc_populate;
>  
>      dc->realize = pnv_lpc_realize;
> +    dc->props = pnv_lpc_properties;
>  }
>  
>  static const TypeInfo pnv_lpc_info = {
> diff --git a/include/hw/ppc/pnv_lpc.h b/include/hw/ppc/pnv_lpc.h
> index ccf969af9448..c78ee4a98c62 100644
> --- a/include/hw/ppc/pnv_lpc.h
> +++ b/include/hw/ppc/pnv_lpc.h
> @@ -67,6 +67,8 @@ typedef struct PnvLpcController {
>  
>      /* PSI to generate interrupts */
>      PnvPsi *psi;
> +
> +    uint32_t chip_id;
>  } PnvLpcController;
>  
>  qemu_irq *pnv_lpc_isa_irq_create(PnvLpcController *lpc, int chip_type,

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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