hw/misc/stm32l4x5_rcc: Add an internal clock multiplexer object

This object is used to represent every multiplexer in the clock tree as
well as every clock output, every presecaler, frequency multiplier, etc.
This allows to use a generic approach for every component of the clock tree
(except the PLLs).

The migration handling is based on hw/misc/zynq_sclr.c.
Three phase reset will be handled in a later commit.

Signed-off-by: Arnaud Minier <arnaud.minier@telecom-paris.fr>
Signed-off-by: Inès Varhol <ines.varhol@telecom-paris.fr>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20240303140643.81957-3-arnaud.minier@telecom-paris.fr
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

hw/misc/stm32l4x5_rcc.c

@@ -36,6 +36,134 @@
 #define LSE_FRQ 32768ULL
 #define LSI_FRQ 32000ULL
 
+static void clock_mux_update(RccClockMuxState *mux)
+{
+    uint64_t src_freq;
+    Clock *current_source = mux->srcs[mux->src];
+    uint32_t freq_multiplier = 0;
+    /*
+     * To avoid rounding errors, we use the clock period instead of the
+     * frequency.
+     * This means that the multiplier of the mux becomes the divider of
+     * the clock and the divider of the mux becomes the multiplier of the
+     * clock.
+     */
+    if (mux->enabled && mux->divider) {
+        freq_multiplier = mux->divider;
+    }
+
+    clock_set_mul_div(mux->out, freq_multiplier, mux->multiplier);
+    clock_update(mux->out, clock_get(current_source));
+
+    src_freq = clock_get_hz(current_source);
+    /* TODO: can we simply detect if the config changed so that we reduce log spam ? */
+    trace_stm32l4x5_rcc_mux_update(mux->id, mux->src, src_freq,
+                                   mux->multiplier, mux->divider);
+}
+
+static void clock_mux_src_update(void *opaque, ClockEvent event)
+{
+    RccClockMuxState **backref = opaque;
+    RccClockMuxState *s = *backref;
+    /*
+     * The backref value is equal to:
+     * s->backref + (sizeof(RccClockMuxState *) * update_src).
+     * By subtracting we can get back the index of the updated clock.
+     */
+    const uint32_t update_src = backref - s->backref;
+    /* Only update if the clock that was updated is the current source */
+    if (update_src == s->src) {
+        clock_mux_update(s);
+    }
+}
+
+static void clock_mux_init(Object *obj)
+{
+    RccClockMuxState *s = RCC_CLOCK_MUX(obj);
+    size_t i;
+
+    for (i = 0; i < RCC_NUM_CLOCK_MUX_SRC; i++) {
+        char *name = g_strdup_printf("srcs[%zu]", i);
+        s->backref[i] = s;
+        s->srcs[i] = qdev_init_clock_in(DEVICE(s), name,
+                                        clock_mux_src_update,
+                                        &s->backref[i],
+                                        ClockUpdate);
+        g_free(name);
+    }
+
+    s->out = qdev_init_clock_out(DEVICE(s), "out");
+}
+
+static void clock_mux_reset_hold(Object *obj)
+{ }
+
+static const VMStateDescription clock_mux_vmstate = {
+    .name = TYPE_RCC_CLOCK_MUX,
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(id, RccClockMuxState),
+        VMSTATE_ARRAY_CLOCK(srcs, RccClockMuxState,
+                            RCC_NUM_CLOCK_MUX_SRC),
+        VMSTATE_BOOL(enabled, RccClockMuxState),
+        VMSTATE_UINT32(src, RccClockMuxState),
+        VMSTATE_UINT32(multiplier, RccClockMuxState),
+        VMSTATE_UINT32(divider, RccClockMuxState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void clock_mux_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    ResettableClass *rc = RESETTABLE_CLASS(klass);
+
+    rc->phases.hold = clock_mux_reset_hold;
+    dc->vmsd = &clock_mux_vmstate;
+}
+
+static void clock_mux_set_enable(RccClockMuxState *mux, bool enabled)
+{
+    if (mux->enabled == enabled) {
+        return;
+    }
+
+    if (enabled) {
+        trace_stm32l4x5_rcc_mux_enable(mux->id);
+    } else {
+        trace_stm32l4x5_rcc_mux_disable(mux->id);
+    }
+
+    mux->enabled = enabled;
+    clock_mux_update(mux);
+}
+
+static void clock_mux_set_factor(RccClockMuxState *mux,
+                                 uint32_t multiplier, uint32_t divider)
+{
+    if (mux->multiplier == multiplier && mux->divider == divider) {
+        return;
+    }
+    trace_stm32l4x5_rcc_mux_set_factor(mux->id,
+        mux->multiplier, multiplier, mux->divider, divider);
+
+    mux->multiplier = multiplier;
+    mux->divider = divider;
+    clock_mux_update(mux);
+}
+
+static void clock_mux_set_source(RccClockMuxState *mux, RccClockMuxSource src)
+{
+    if (mux->src == src) {
+        return;
+    }
+
+    trace_stm32l4x5_rcc_mux_set_src(mux->id, mux->src, src);
+    mux->src = src;
+    clock_mux_update(mux);
+}
+
 static void rcc_update_irq(Stm32l4x5RccState *s)
 {
     if (s->cifr & CIFR_IRQ_MASK) {
@@ -335,6 +463,7 @@ static const ClockPortInitArray stm32l4x5_rcc_clocks = {
 static void stm32l4x5_rcc_init(Object *obj)
 {
     Stm32l4x5RccState *s = STM32L4X5_RCC(obj);
+    size_t i;
 
     sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->irq);
 
@@ -344,6 +473,14 @@ static void stm32l4x5_rcc_init(Object *obj)
 
     qdev_init_clocks(DEVICE(s), stm32l4x5_rcc_clocks);
 
+    for (i = 0; i < RCC_NUM_CLOCK_MUX; i++) {
+
+        object_initialize_child(obj, "clock[*]",
+                                &s->clock_muxes[i],
+                                TYPE_RCC_CLOCK_MUX);
+
+    }
+
     s->gnd = clock_new(obj, "gnd");
 }
 
@@ -396,6 +533,7 @@ static const VMStateDescription vmstate_stm32l4x5_rcc = {
 static void stm32l4x5_rcc_realize(DeviceState *dev, Error **errp)
 {
     Stm32l4x5RccState *s = STM32L4X5_RCC(dev);
+    size_t i;
 
     if (s->hse_frequency <  4000000ULL ||
         s->hse_frequency > 48000000ULL) {
@@ -405,10 +543,26 @@ static void stm32l4x5_rcc_realize(DeviceState *dev, Error **errp)
             return;
         }
 
+    for (i = 0; i < RCC_NUM_CLOCK_MUX; i++) {
+        RccClockMuxState *clock_mux = &s->clock_muxes[i];
+
+        if (!qdev_realize(DEVICE(clock_mux), NULL, errp)) {
+            return;
+        }
+    }
+
     clock_update_hz(s->msi_rc, MSI_DEFAULT_FRQ);
     clock_update_hz(s->sai1_extclk, s->sai1_extclk_frequency);
     clock_update_hz(s->sai2_extclk, s->sai2_extclk_frequency);
     clock_update(s->gnd, 0);
+
+    /*
+     * Dummy values to make compilation pass.
+     * Removed in later commits.
+     */
+    clock_mux_set_source(&s->clock_muxes[0], RCC_CLOCK_MUX_SRC_GND);
+    clock_mux_set_enable(&s->clock_muxes[0], true);
+    clock_mux_set_factor(&s->clock_muxes[0], 1, 1);
 }
 
 static Property stm32l4x5_rcc_properties[] = {
@@ -440,6 +594,12 @@ static const TypeInfo stm32l4x5_rcc_types[] = {
         .instance_size  = sizeof(Stm32l4x5RccState),
         .instance_init  = stm32l4x5_rcc_init,
         .class_init     = stm32l4x5_rcc_class_init,
+    }, {
+        .name = TYPE_RCC_CLOCK_MUX,
+        .parent = TYPE_DEVICE,
+        .instance_size = sizeof(RccClockMuxState),
+        .instance_init = clock_mux_init,
+        .class_init = clock_mux_class_init,
     }
 };