Re: [PATCH v5 2/3] hw/ppc: Add nest1 chiplet model

[Nicholas Piggin]

For this and actually the last patch too, it would be good to mention
(possibly in a header comment in the file too) what actual functionality
is being provided/modeled. It looks like it's just modeling behaviour of
reads and writes for some registers.

Oh, and sorry I didn't follow development and comments on this too
closely, so forgive me if I've missed things already said. I'll go
back and read through the series.

On Fri Nov 24, 2023 at 8:15 PM AEST, Chalapathi V wrote:
> The nest1 chiplet handle the high speed i/o traffic over PCIe and others.
> The nest1 chiplet consists of PowerBus Fabric controller,
> nest Memory Management Unit, chiplet control unit and more.
>
> This commit creates a nest1 chiplet model and initialize and realize the
> pervasive chiplet model where chiplet control registers are implemented.
>
> This commit also implement the read/write method for the powerbus scom
> registers

The powerbus scom registers, are those specifically for the PowerBus
Fabric controller mentioned in the first paragraph, or is it a more
general set of registers for the chiplet?

>
> Signed-off-by: Chalapathi V <chalapathi.v@linux.ibm.com>
> ---
>  include/hw/ppc/pnv_nest_chiplet.h |  36 ++++++
>  include/hw/ppc/pnv_xscom.h        |   6 +
>  hw/ppc/pnv_nest1_chiplet.c        | 197 ++++++++++++++++++++++++++++++
>  hw/ppc/meson.build                |   1 +
>  4 files changed, 240 insertions(+)
>  create mode 100644 include/hw/ppc/pnv_nest_chiplet.h
>  create mode 100644 hw/ppc/pnv_nest1_chiplet.c
>
> diff --git a/include/hw/ppc/pnv_nest_chiplet.h 
> b/include/hw/ppc/pnv_nest_chiplet.h
> new file mode 100644
> index 0000000000..845030fb1a
> --- /dev/null
> +++ b/include/hw/ppc/pnv_nest_chiplet.h
> @@ -0,0 +1,36 @@
> +/*
> + * QEMU PowerPC nest chiplet model
> + *
> + * Copyright (c) 2023, IBM Corporation.
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + *
> + * This code is licensed under the GPL version 2 or later. See the
> + * COPYING file in the top-level directory.
> + *
> + */
> +
> +#ifndef PPC_PNV_NEST1_CHIPLET_H
> +#define PPC_PNV_NEST1_CHIPLET_H
> +
> +#include "hw/ppc/pnv_pervasive.h"
> +
> +#define TYPE_PNV_NEST1 "pnv-nest1-chiplet"
> +#define PNV_NEST1(obj) OBJECT_CHECK(PnvNest1, (obj), TYPE_PNV_NEST1)
> +
> +typedef struct pb_scom {
> +    uint64_t mode;
> +    uint64_t hp_mode2_curr;
> +} pb_scom;
> +
> +typedef struct PnvNest1 {

Naming nitpicking again... 

The main ifndef guard for header files should match the file name, so
the file should be called pnv_nest1_chiplet.h (and that matches the .c
file too).

I think this struct should be called Nest1Chiplet too. Nest1 is
unambiguously the name of a specific chiplet, but it's a little easy
to miss the 1, and if we get a bunch more chiplets I think it will
be nicer to have Chiplet in the name.

Thanks,
Nick

> +    DeviceState parent;
> +    MemoryRegion xscom_pb_eq_regs;
> +    MemoryRegion xscom_pb_es_regs;
> +    /* common pervasive chiplet unit */
> +    PnvPerv perv;
> +    /* powerbus racetrack registers */
> +    pb_scom eq[8];
> +    pb_scom es[4];
> +} PnvNest1;
> +#endif /*PPC_PNV_NEST1 */
> diff --git a/include/hw/ppc/pnv_xscom.h b/include/hw/ppc/pnv_xscom.h
> index d09d10f32b..df68a1c20e 100644
> --- a/include/hw/ppc/pnv_xscom.h
> +++ b/include/hw/ppc/pnv_xscom.h
> @@ -173,6 +173,12 @@ struct PnvXScomInterfaceClass {
>  #define PNV10_XSCOM_NEST1_CTRL_CHIPLET_BASE      0x3000000
>  #define PNV10_XSCOM_CTRL_CHIPLET_SIZE            0x400
>  
> +#define PNV10_XSCOM_NEST1_PB_SCOM_EQ_BASE      0x3011000
> +#define PNV10_XSCOM_NEST1_PB_SCOM_EQ_SIZE      0x200
> +
> +#define PNV10_XSCOM_NEST1_PB_SCOM_ES_BASE      0x3011300
> +#define PNV10_XSCOM_NEST1_PB_SCOM_ES_SIZE      0x100
> +
>  #define PNV10_XSCOM_PEC_NEST_BASE  0x3011800 /* index goes downwards ... */
>  #define PNV10_XSCOM_PEC_NEST_SIZE  0x100
>  
> diff --git a/hw/ppc/pnv_nest1_chiplet.c b/hw/ppc/pnv_nest1_chiplet.c
> new file mode 100644
> index 0000000000..609d5f1be4
> --- /dev/null
> +++ b/hw/ppc/pnv_nest1_chiplet.c
> @@ -0,0 +1,197 @@
> +/*
> + * QEMU PowerPC nest1 chiplet model
> + *
> + * Copyright (c) 2023, IBM Corporation.
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + *
> + * This code is licensed under the GPL version 2 or later. See the
> + * COPYING file in the top-level directory.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu/log.h"
> +#include "hw/qdev-properties.h"
> +#include "hw/ppc/pnv.h"
> +#include "hw/ppc/pnv_xscom.h"
> +#include "hw/ppc/pnv_nest_chiplet.h"
> +#include "hw/ppc/pnv_pervasive.h"
> +#include "hw/ppc/fdt.h"
> +#include <libfdt.h>
> +
> +/*
> + * The nest1 chiplet contains chiplet control unit,
> + * PowerBus/RaceTrack/Bridge logic, nest Memory Management Unit(nMMU)
> + * and more.
> + */
> +
> +#define PB_SCOM_EQ0_HP_MODE2_CURR      0xe
> +#define PB_SCOM_ES3_MODE               0x8a
> +
> +static uint64_t pnv_nest1_pb_scom_eq_read(void *opaque, hwaddr addr,
> +                                                  unsigned size)
> +{
> +    PnvNest1 *nest1 = PNV_NEST1(opaque);
> +    int reg = addr >> 3;
> +    uint64_t val = ~0ull;
> +
> +    switch (reg) {
> +    case PB_SCOM_EQ0_HP_MODE2_CURR:
> +        val = nest1->eq[0].hp_mode2_curr;
> +        break;
> +    default:
> +        qemu_log_mask(LOG_UNIMP, "%s: Invalid xscom read at 0x%" PRIx32 "\n",
> +                      __func__, reg);
> +    }
> +    return val;
> +}
> +
> +static void pnv_nest1_pb_scom_eq_write(void *opaque, hwaddr addr,
> +                                               uint64_t val, unsigned size)
> +{
> +    PnvNest1 *nest1 = PNV_NEST1(opaque);
> +    int reg = addr >> 3;
> +
> +    switch (reg) {
> +    case PB_SCOM_EQ0_HP_MODE2_CURR:
> +        nest1->eq[0].hp_mode2_curr = val;
> +        break;
> +    default:
> +        qemu_log_mask(LOG_UNIMP, "%s: Invalid xscom write at 0x%" PRIx32 
> "\n",
> +                      __func__, reg);
> +    }
> +}
> +
> +static const MemoryRegionOps pnv_nest1_pb_scom_eq_ops = {
> +    .read = pnv_nest1_pb_scom_eq_read,
> +    .write = pnv_nest1_pb_scom_eq_write,
> +    .valid.min_access_size = 8,
> +    .valid.max_access_size = 8,
> +    .impl.min_access_size = 8,
> +    .impl.max_access_size = 8,
> +    .endianness = DEVICE_BIG_ENDIAN,
> +};
> +
> +static uint64_t pnv_nest1_pb_scom_es_read(void *opaque, hwaddr addr,
> +                                          unsigned size)
> +{
> +    PnvNest1 *nest1 = PNV_NEST1(opaque);
> +    int reg = addr >> 3;
> +    uint64_t val = ~0ull;
> +
> +    switch (reg) {
> +    case PB_SCOM_ES3_MODE:
> +        val = nest1->es[3].mode;
> +        break;
> +    default:
> +        qemu_log_mask(LOG_UNIMP, "%s: Invalid xscom read at 0x%" PRIx32 "\n",
> +                      __func__, reg);
> +    }
> +    return val;
> +}
> +
> +static void pnv_nest1_pb_scom_es_write(void *opaque, hwaddr addr,
> +                                               uint64_t val, unsigned size)
> +{
> +    PnvNest1 *nest1 = PNV_NEST1(opaque);
> +    int reg = addr >> 3;
> +
> +    switch (reg) {
> +    case PB_SCOM_ES3_MODE:
> +        nest1->es[3].mode = val;
> +        break;
> +    default:
> +        qemu_log_mask(LOG_UNIMP, "%s: Invalid xscom write at 0x%" PRIx32 
> "\n",
> +                      __func__, reg);
> +    }
> +}
> +
> +static const MemoryRegionOps pnv_nest1_pb_scom_es_ops = {
> +    .read = pnv_nest1_pb_scom_es_read,
> +    .write = pnv_nest1_pb_scom_es_write,
> +    .valid.min_access_size = 8,
> +    .valid.max_access_size = 8,
> +    .impl.min_access_size = 8,
> +    .impl.max_access_size = 8,
> +    .endianness = DEVICE_BIG_ENDIAN,
> +};
> +
> +static void pnv_nest1_realize(DeviceState *dev, Error **errp)
> +{
> +    PnvNest1 *nest1 = PNV_NEST1(dev);
> +
> +    /* perv chiplet initialize and realize */
> +    object_initialize_child(OBJECT(nest1), "perv", &nest1->perv, 
> TYPE_PNV_PERV);
> +    object_property_set_str(OBJECT(&nest1->perv), "parent-obj-name", "nest1",
> +                                   errp);
> +    if (!qdev_realize(DEVICE(&nest1->perv), NULL, errp)) {
> +        return;
> +    }
> +
> +    /* Nest1 chiplet power bus EQ xscom region */
> +    pnv_xscom_region_init(&nest1->xscom_pb_eq_regs, OBJECT(nest1),
> +                          &pnv_nest1_pb_scom_eq_ops, nest1,
> +                          "xscom-nest1-pb-scom-eq-regs",
> +                          PNV10_XSCOM_NEST1_PB_SCOM_EQ_SIZE);
> +
> +    /* Nest1 chiplet power bus ES xscom region */
> +    pnv_xscom_region_init(&nest1->xscom_pb_es_regs, OBJECT(nest1),
> +                          &pnv_nest1_pb_scom_es_ops, nest1,
> +                          "xscom-nest1-pb-scom-es-regs",
> +                          PNV10_XSCOM_NEST1_PB_SCOM_ES_SIZE);
> +}
> +
> +static int pnv_nest1_dt_xscom(PnvXScomInterface *dev, void *fdt,
> +                             int offset)
> +{
> +    PnvNest1 *nest1 = PNV_NEST1(dev);
> +    g_autofree char *name = NULL;
> +    int nest1_offset = 0;
> +    const char compat[] = "ibm,power10-nest1-chiplet";
> +    uint32_t reg[] = {
> +        cpu_to_be32(PNV10_XSCOM_NEST1_PB_SCOM_EQ_BASE),
> +        cpu_to_be32(PNV10_XSCOM_NEST1_PB_SCOM_EQ_SIZE),
> +        cpu_to_be32(PNV10_XSCOM_NEST1_PB_SCOM_ES_BASE),
> +        cpu_to_be32(PNV10_XSCOM_NEST1_PB_SCOM_ES_SIZE)
> +    };
> +
> +    /* populate perv_chiplet control_regs */
> +    pnv_perv_dt(&nest1->perv, PNV10_XSCOM_NEST1_CTRL_CHIPLET_BASE, fdt, 
> offset);
> +
> +    name = g_strdup_printf("nest1@%x", PNV10_XSCOM_NEST1_PB_SCOM_EQ_BASE);
> +    nest1_offset = fdt_add_subnode(fdt, offset, name);
> +    _FDT(nest1_offset);
> +
> +    _FDT(fdt_setprop(fdt, nest1_offset, "reg", reg, sizeof(reg)));
> +    _FDT(fdt_setprop(fdt, nest1_offset, "compatible", compat, 
> sizeof(compat)));
> +    return 0;
> +}
> +
> +static void pnv_nest1_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +    PnvXScomInterfaceClass *xscomc = PNV_XSCOM_INTERFACE_CLASS(klass);
> +
> +    xscomc->dt_xscom = pnv_nest1_dt_xscom;
> +
> +    dc->desc = "PowerNV nest1 chiplet";
> +    dc->realize = pnv_nest1_realize;
> +}
> +
> +static const TypeInfo pnv_nest1_info = {
> +    .name          = TYPE_PNV_NEST1,
> +    .parent        = TYPE_DEVICE,
> +    .instance_size = sizeof(PnvNest1),
> +    .class_init    = pnv_nest1_class_init,
> +    .interfaces    = (InterfaceInfo[]) {
> +        { TYPE_PNV_XSCOM_INTERFACE },
> +        { }
> +    }
> +};
> +
> +static void pnv_nest1_register_types(void)
> +{
> +    type_register_static(&pnv_nest1_info);
> +}
> +
> +type_init(pnv_nest1_register_types);
> diff --git a/hw/ppc/meson.build b/hw/ppc/meson.build
> index 37a7a8935d..7b8b87596a 100644
> --- a/hw/ppc/meson.build
> +++ b/hw/ppc/meson.build
> @@ -52,6 +52,7 @@ ppc_ss.add(when: 'CONFIG_POWERNV', if_true: files(
>    'pnv_homer.c',
>    'pnv_pnor.c',
>    'pnv_pervasive.c',
> +  'pnv_nest1_chiplet.c',
>  ))
>  # PowerPC 4xx boards
>  ppc_ss.add(when: 'CONFIG_PPC405', if_true: files(