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/*
* 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). A mux is configured to select a given source through its
* control register. Each mux has one output clock that also goes out of the
* CPRMAN. This output clock usually 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)
{
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 = {
/*
* Although this hasn't been checked against real hardware, nor the
* information can be found in a datasheet, it seems reasonable because
* of the "PASSWORD" magic value found in every registers.
*/
.min_access_size = 4,
.max_access_size = 4,
.unaligned = false,
},
.impl = {
.max_access_size = 4,
},
};
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 void cprman_init(Object *obj)
{
BCM2835CprmanState *s = CPRMAN(obj);
s->xosc = clock_new(obj, "xosc");
memory_region_init_io(&s->iomem, obj, &cprman_ops,
s, "bcm2835-cprman", 0x2000);
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-hz", BCM2835CprmanState, xosc_freq, 19200000),
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);
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