Re: [PATCH 04/14] hw/arm/raspi: add a skeleton implementation of the cprman

[Luc Michel <luc@lmichel.fr>]

On 23:05 Sat 26 Sep     , Philippe Mathieu-Daudé wrote:
> On 9/25/20 12:17 PM, Luc Michel wrote:
> > The BCM2835 cprman is the clock manager of the SoC. It is composed of a
> 
> Can we use CPRMAN in caps?
> 
> > main oscillator, and several sub-components (PLLs, multiplexers, ...) to
> > generate the BCM2835 clock tree.
> > 
> > This commit adds a skeleton of the cprman, with a dummy register
> > read/write implementation. It embeds the main oscillator (xosc) from
> > which all the clocks will be derived.
> > 
> > Signed-off-by: Luc Michel <luc@lmichel.fr>
> > ---
> >  include/hw/arm/bcm2835_peripherals.h       |   3 +-
> >  include/hw/misc/bcm2835_cprman.h           |  37 +++++
> >  include/hw/misc/bcm2835_cprman_internals.h |  24 +++
> >  hw/arm/bcm2835_peripherals.c               |  11 +-
> >  hw/misc/bcm2835_cprman.c                   | 171 +++++++++++++++++++++
> >  hw/misc/meson.build                        |   1 +
> >  hw/misc/trace-events                       |   5 +
> >  7 files changed, 250 insertions(+), 2 deletions(-)
> >  create mode 100644 include/hw/misc/bcm2835_cprman.h
> >  create mode 100644 include/hw/misc/bcm2835_cprman_internals.h
> >  create mode 100644 hw/misc/bcm2835_cprman.c
> > 
> > diff --git a/include/hw/arm/bcm2835_peripherals.h b/include/hw/arm/bcm2835_peripherals.h
> > index 199088425a..002bb5e73b 100644
> > --- a/include/hw/arm/bcm2835_peripherals.h
> > +++ b/include/hw/arm/bcm2835_peripherals.h
> > @@ -21,10 +21,11 @@
> >  #include "hw/misc/bcm2835_property.h"
> >  #include "hw/misc/bcm2835_rng.h"
> >  #include "hw/misc/bcm2835_mbox.h"
> >  #include "hw/misc/bcm2835_mphi.h"
> >  #include "hw/misc/bcm2835_thermal.h"
> > +#include "hw/misc/bcm2835_cprman.h"
> >  #include "hw/sd/sdhci.h"
> >  #include "hw/sd/bcm2835_sdhost.h"
> >  #include "hw/gpio/bcm2835_gpio.h"
> >  #include "hw/timer/bcm2835_systmr.h"
> >  #include "hw/usb/hcd-dwc2.h"
> > @@ -45,11 +46,11 @@ struct BCM2835PeripheralState {
> >  
> >      BCM2835SystemTimerState systmr;
> >      BCM2835MphiState mphi;
> >      UnimplementedDeviceState armtmr;
> >      UnimplementedDeviceState powermgt;
> > -    UnimplementedDeviceState cprman;
> > +    BCM2835CprmanState cprman;
> >      PL011State uart0;
> >      BCM2835AuxState aux;
> >      BCM2835FBState fb;
> >      BCM2835DMAState dma;
> >      BCM2835ICState ic;
> > diff --git a/include/hw/misc/bcm2835_cprman.h b/include/hw/misc/bcm2835_cprman.h
> > new file mode 100644
> > index 0000000000..de9bd01b23
> > --- /dev/null
> > +++ b/include/hw/misc/bcm2835_cprman.h
> > @@ -0,0 +1,37 @@
> > +/*
> > + * BCM2835 cprman clock manager
> > + *
> > + * Copyright (c) 2020 Luc Michel <luc@lmichel.fr>
> > + *
> > + * SPDX-License-Identifier: GPL-2.0-or-later
> > + */
> > +
> > +#ifndef HW_MISC_CPRMAN_H
> > +#define HW_MISC_CPRMAN_H
> > +
> > +#include "hw/sysbus.h"
> > +#include "hw/qdev-clock.h"
> > +
> > +#define TYPE_BCM2835_CPRMAN "bcm2835-cprman"
> > +
> > +typedef struct BCM2835CprmanState BCM2835CprmanState;
> > +
> > +DECLARE_INSTANCE_CHECKER(BCM2835CprmanState, CPRMAN,
> > +                         TYPE_BCM2835_CPRMAN)
> > +
> > +#define CPRMAN_NUM_REGS (0x2000 / sizeof(uint32_t))
> > +
> > +struct BCM2835CprmanState {
> > +    /*< private >*/
> > +    SysBusDevice parent_obj;
> > +
> > +    /*< public >*/
> > +    MemoryRegion iomem;
> > +
> > +    uint32_t regs[CPRMAN_NUM_REGS];
> > +    uint32_t xosc_freq;
> > +
> > +    Clock *xosc;
> > +};
> > +
> > +#endif
> > diff --git a/include/hw/misc/bcm2835_cprman_internals.h b/include/hw/misc/bcm2835_cprman_internals.h
> > new file mode 100644
> > index 0000000000..6a10b60930
> > --- /dev/null
> > +++ b/include/hw/misc/bcm2835_cprman_internals.h
> > @@ -0,0 +1,24 @@
> > +/*
> > + * BCM2835 cprman clock manager
> > + *
> > + * Copyright (c) 2020 Luc Michel <luc@lmichel.fr>
> > + *
> > + * SPDX-License-Identifier: GPL-2.0-or-later
> > + */
> > +
> > +#ifndef HW_MISC_CPRMAN_INTERNALS_H
> > +#define HW_MISC_CPRMAN_INTERNALS_H
> > +
> > +#include "hw/registerfields.h"
> > +#include "hw/misc/bcm2835_cprman.h"
> > +
> > +/* Register map */
> > +
> > +/*
> > + * This field is common to all registers. Each register write value must match
> > + * the CPRMAN_PASSWORD magic value in its 8 MSB.
> > + */
> > +FIELD(CPRMAN, PASSWORD, 24, 8)
> > +#define CPRMAN_PASSWORD 0x5a
> 
> s/PASSWORD/KEY/?
I'm not a big fan of this name either, but this is actually how this
field is named in the datasheet and in various sources.

See:
  - https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf
    (page 107)
  - https://elinux.org/BCM2835_registers#CM (auto-generated from
    Broadcom GPU related code)
  - The Linux driver also use this name FWIW.
> 
> > +
> > +#endif
> > diff --git a/hw/arm/bcm2835_peripherals.c b/hw/arm/bcm2835_peripherals.c
> > index f0802c91e0..958aadeeb9 100644
> > --- a/hw/arm/bcm2835_peripherals.c
> > +++ b/hw/arm/bcm2835_peripherals.c
> > @@ -119,10 +119,13 @@ static void bcm2835_peripherals_init(Object *obj)
> >      object_initialize_child(obj, "mphi", &s->mphi, TYPE_BCM2835_MPHI);
> >  
> >      /* DWC2 */
> >      object_initialize_child(obj, "dwc2", &s->dwc2, TYPE_DWC2_USB);
> >  
> > +    /* CPRMAN clock manager */
> > +    object_initialize_child(obj, "cprman", &s->cprman, TYPE_BCM2835_CPRMAN);
> > +
> >      object_property_add_const_link(OBJECT(&s->dwc2), "dma-mr",
> >                                     OBJECT(&s->gpu_bus_mr));
> >  }
> >  
> >  static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
> > @@ -158,10 +161,17 @@ static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
> >      /* Interrupt Controller */
> >      if (!sysbus_realize(SYS_BUS_DEVICE(&s->ic), errp)) {
> >          return;
> >      }
> >  
> > +    /* CPRMAN clock manager */
> > +    if (!sysbus_realize(SYS_BUS_DEVICE(&s->cprman), errp)) {
> > +        return;
> > +    }
> > +    memory_region_add_subregion(&s->peri_mr, CPRMAN_OFFSET,
> > +                sysbus_mmio_get_region(SYS_BUS_DEVICE(&s->cprman), 0));
> > +
> >      memory_region_add_subregion(&s->peri_mr, ARMCTRL_IC_OFFSET,
> >                  sysbus_mmio_get_region(SYS_BUS_DEVICE(&s->ic), 0));
> >      sysbus_pass_irq(SYS_BUS_DEVICE(s), SYS_BUS_DEVICE(&s->ic));
> >  
> >      /* Sys Timer */
> > @@ -343,11 +353,10 @@ static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
> >          qdev_get_gpio_in_named(DEVICE(&s->ic), BCM2835_IC_GPU_IRQ,
> >                                 INTERRUPT_USB));
> >  
> >      create_unimp(s, &s->armtmr, "bcm2835-sp804", ARMCTRL_TIMER0_1_OFFSET, 0x40);
> >      create_unimp(s, &s->powermgt, "bcm2835-powermgt", PM_OFFSET, 0x114);
> > -    create_unimp(s, &s->cprman, "bcm2835-cprman", CPRMAN_OFFSET, 0x2000);
> >      create_unimp(s, &s->i2s, "bcm2835-i2s", I2S_OFFSET, 0x100);
> >      create_unimp(s, &s->smi, "bcm2835-smi", SMI_OFFSET, 0x100);
> >      create_unimp(s, &s->spi[0], "bcm2835-spi0", SPI0_OFFSET, 0x20);
> >      create_unimp(s, &s->bscsl, "bcm2835-spis", BSC_SL_OFFSET, 0x100);
> >      create_unimp(s, &s->i2c[0], "bcm2835-i2c0", BSC0_OFFSET, 0x20);
> > diff --git a/hw/misc/bcm2835_cprman.c b/hw/misc/bcm2835_cprman.c
> > new file mode 100644
> > index 0000000000..d2ea0c9236
> > --- /dev/null
> > +++ b/hw/misc/bcm2835_cprman.c
> > @@ -0,0 +1,171 @@
> > +/*
> > + * BCM2835 cprman clock manager
> > + *
> > + * Copyright (c) 2020 Luc Michel <luc@lmichel.fr>
> > + *
> > + * SPDX-License-Identifier: GPL-2.0-or-later
> > + */
> > +
> > +/*
> > + * This peripheral is roughly divided into 3 main parts:
> > + *   - the PLLs
> > + *   - the PLL channels
> > + *   - the clock muxes
> > + *
> > + * A main oscillator (xosc) feeds all the PLLs. Each PLLs has one or more
> > + * channels. Those channel are then connected to the clock muxes. Each mux has
> > + * multiples sources (usually the xosc, some of the PLL channels and some "test
> > + * debug" clocks). It can selects one or the other through a control register.
> 
> "It" is unclear (to me) in this sentence. Assuming the mux.
> 
> > + * Each mux has one output clock that also goes out of the CPRMAN. It usually
> 
> Here is "It" the mux or the output clock? Assuming the mux.
> 
> > + * connects to another peripheral in the SoC (so a given mux is dedicated to a
> > + * peripheral).
> > + *
> > + * At each level (PLL, channel and mux), the clock can be altered through
> > + * dividers (and multipliers in case of the PLLs), and can be disabled (in this
> > + * case, the next levels see no clock).
> > + *
> > + * This can be sum-up as follows (this is an example and not the actual BCM2835
> > + * clock tree):
> > + *
> > + *          /-->[PLL]-|->[PLL channel]--...            [mux]--> to peripherals
> > + *          |         |->[PLL channel]  muxes takes    [mux]
> > + *          |         \->[PLL channel]  inputs from    [mux]
> > + *          |                           some channels  [mux]
> > + * [xosc]---|-->[PLL]-|->[PLL channel]  and other srcs [mux]
> > + *          |         \->[PLL channel]           ...-->[mux]
> > + *          |                                          [mux]
> > + *          \-->[PLL]--->[PLL channel]                 [mux]
> > + *
> > + * The page at https://elinux.org/The_Undocumented_Pi gives the actual clock
> > + * tree configuration.
> > + */
> > +
> > +#include "qemu/osdep.h"
> > +#include "qemu/log.h"
> > +#include "migration/vmstate.h"
> > +#include "hw/qdev-properties.h"
> > +#include "hw/misc/bcm2835_cprman.h"
> > +#include "hw/misc/bcm2835_cprman_internals.h"
> > +#include "trace.h"
> > +
> > +/* CPRMAN "top level" model */
> > +
> > +static uint64_t cprman_read(void *opaque, hwaddr offset,
> > +                                    unsigned size)
> 
> Indent off.
> 
> > +{
> > +    BCM2835CprmanState *s = CPRMAN(opaque);
> > +    uint64_t r = 0;
> > +    size_t idx = offset / sizeof(uint32_t);
> > +
> > +    switch (idx) {
> > +    default:
> > +        r = s->regs[idx];
> > +    }
> > +
> > +    trace_bcm2835_cprman_read(offset, r);
> > +    return r;
> > +}
> > +
> > +static void cprman_write(void *opaque, hwaddr offset,
> > +                         uint64_t value, unsigned size)
> > +{
> > +    BCM2835CprmanState *s = CPRMAN(opaque);
> > +    size_t idx = offset / sizeof(uint32_t);
> > +
> > +    if (FIELD_EX32(value, CPRMAN, PASSWORD) != CPRMAN_PASSWORD) {
> > +        trace_bcm2835_cprman_write_invalid_magic(offset, value);
> > +        return;
> > +    }
> > +
> > +    value &= ~R_CPRMAN_PASSWORD_MASK;
> > +
> > +    trace_bcm2835_cprman_write(offset, value);
> > +    s->regs[idx] = value;
> > +
> > +}
> > +
> > +static const MemoryRegionOps cprman_ops = {
> > +    .read = cprman_read,
> > +    .write = cprman_write,
> > +    .endianness = DEVICE_LITTLE_ENDIAN,
> > +    .valid      = {
> > +        .min_access_size        = 4,
> > +        .max_access_size        = 4,
> 
> I couldn't find this in the public datasheets (any pointer?).
> 
> Since your implementation is 32bit, can you explicit .impl
> min/max = 4?

I could not find this information either, but I assumed this is the
case, mainly because of the 'PASSWORD' field in all registers.

Regarding .impl, I thought that having .valid was enough?

> 
> > +        .unaligned              = false,
> > +    },
> > +};
> > +
> > +static void cprman_reset(DeviceState *dev)
> > +{
> > +    BCM2835CprmanState *s = CPRMAN(dev);
> > +
> > +    memset(s->regs, 0, sizeof(s->regs));
> > +
> > +    clock_update_hz(s->xosc, s->xosc_freq);
> > +}
> > +
> > +static Clock *init_internal_clock(BCM2835CprmanState *s,
> > +                                  const char *name)
> 
> Interesting. Shouldn't this be a public function from the
> Clock API? (Taking Object + name arguments)?
> 
Yes, I hesitated to do just that. I'll add a patch for it when I re-roll.
> > +{
> > +    Object *obj;
> > +    Clock *clk;
> > +
> > +    obj = object_new(TYPE_CLOCK);
> > +    object_property_add_child(OBJECT(s), name, obj);
> > +    object_unref(obj);
> > +
> > +    clk = CLOCK(obj);
> > +    clock_setup_canonical_path(clk);
> > +
> > +    return clk;
> > +}
> > +
> > +static void cprman_init(Object *obj)
> > +{
> > +    BCM2835CprmanState *s = CPRMAN(obj);
> > +
> > +    s->xosc = init_internal_clock(s, "xosc");
> > +
> > +    memory_region_init_io(&s->iomem, obj, &cprman_ops,
> > +                          s, "bcm2835-cprman", 0x2000);
> 
> Again assuming this is a 8KB MMIO device:
> 
> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

Thanks!

-- 
Luc

> 
> > +    sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->iomem);
> > +}
> > +
> > +static const VMStateDescription cprman_vmstate = {
> > +    .name = TYPE_BCM2835_CPRMAN,
> > +    .version_id = 1,
> > +    .minimum_version_id = 1,
> > +    .fields = (VMStateField[]) {
> > +        VMSTATE_UINT32_ARRAY(regs, BCM2835CprmanState, CPRMAN_NUM_REGS),
> > +        VMSTATE_END_OF_LIST()
> > +    }
> > +};
> > +
> > +static Property cprman_properties[] = {
> > +    DEFINE_PROP_UINT32("xosc-freq", BCM2835CprmanState, xosc_freq, 19200000),
> 
> Eventually "xosc-freq-hz".
> 
> > +    DEFINE_PROP_END_OF_LIST()
> > +};
> > +
> > +static void cprman_class_init(ObjectClass *klass, void *data)
> > +{
> > +    DeviceClass *dc = DEVICE_CLASS(klass);
> > +
> > +    dc->reset = cprman_reset;
> > +    dc->vmsd = &cprman_vmstate;
> > +    device_class_set_props(dc, cprman_properties);
> > +}
> > +
> > +static const TypeInfo cprman_info = {
> > +    .name = TYPE_BCM2835_CPRMAN,
> > +    .parent = TYPE_SYS_BUS_DEVICE,
> > +    .instance_size = sizeof(BCM2835CprmanState),
> > +    .class_init = cprman_class_init,
> > +    .instance_init = cprman_init,
> > +};
> > +
> > +static void cprman_register_types(void)
> > +{
> > +    type_register_static(&cprman_info);
> > +}
> > +
> > +type_init(cprman_register_types);
> > diff --git a/hw/misc/meson.build b/hw/misc/meson.build
> > index 793d45b1dc..c94cf70e82 100644
> > --- a/hw/misc/meson.build
> > +++ b/hw/misc/meson.build
> > @@ -71,10 +71,11 @@ softmmu_ss.add(when: 'CONFIG_RASPI', if_true: files(
> >    'bcm2835_mbox.c',
> >    'bcm2835_mphi.c',
> >    'bcm2835_property.c',
> >    'bcm2835_rng.c',
> >    'bcm2835_thermal.c',
> > +  'bcm2835_cprman.c',
> >  ))
> >  softmmu_ss.add(when: 'CONFIG_SLAVIO', if_true: files('slavio_misc.c'))
> >  softmmu_ss.add(when: 'CONFIG_ZYNQ', if_true: files('zynq_slcr.c', 'zynq-xadc.c'))
> >  softmmu_ss.add(when: 'CONFIG_STM32F2XX_SYSCFG', if_true: files('stm32f2xx_syscfg.c'))
> >  softmmu_ss.add(when: 'CONFIG_STM32F4XX_SYSCFG', if_true: files('stm32f4xx_syscfg.c'))
> > diff --git a/hw/misc/trace-events b/hw/misc/trace-events
> > index 6054f9adf3..d718a2b177 100644
> > --- a/hw/misc/trace-events
> > +++ b/hw/misc/trace-events
> > @@ -224,5 +224,10 @@ grlib_ahb_pnp_read(uint64_t addr, uint32_t value) "AHB PnP read addr:0x%03"PRIx6
> >  grlib_apb_pnp_read(uint64_t addr, uint32_t value) "APB PnP read addr:0x%03"PRIx64" data:0x%08x"
> >  
> >  # pca9552.c
> >  pca955x_gpio_status(const char *description, const char *buf) "%s GPIOs 0-15 [%s]"
> >  pca955x_gpio_change(const char *description, unsigned id, unsigned prev_state, unsigned current_state) "%s GPIO id:%u status: %u -> %u"
> > +
> > +# bcm2835_cprman.c
> > +bcm2835_cprman_read(uint64_t offset, uint64_t value) "offset:0x%" PRIx64 " value:0x%" PRIx64
> > +bcm2835_cprman_write(uint64_t offset, uint64_t value) "offset:0x%" PRIx64 " value:0x%" PRIx64
> > +bcm2835_cprman_write_invalid_magic(uint64_t offset, uint64_t value) "offset:0x%" PRIx64 " value:0x%" PRIx64
> >