hw/misc/bcm2835_cprman: add a clock mux skeleton implementation

The clock multiplexers are the last clock stage in the CPRMAN. Each mux
outputs one clock signal that goes out of the CPRMAN to the SoC
peripherals.

Each mux has at most 10 sources. The sources 0 to 3 are common to all
muxes. They are:
   0. ground (no clock signal)
   1. the main oscillator (xosc)
   2. "test debug 0" clock
   3. "test debug 1" clock

Test debug 0 and 1 are actual clock muxes that can be used as sources to
other muxes (for debug purpose).

Sources 4 to 9 are mux specific and can be unpopulated (grounded). Those
sources are fed by the PLL channels outputs.

One corner case exists for DSI0E and DSI0P muxes. They have their source
number 4 connected to an intermediate multiplexer that can select
between PLLA-DSI0 and PLLD-DSI0 channel. This multiplexer is called
DSI0HSCK and is not a clock mux as such. It is really a simple mux from
the hardware point of view (see https://elinux.org/The_Undocumented_Pi).
This mux is not implemented in this commit.

Note that there is some muxes for which sources are unknown (because of
a lack of documentation). For those cases all the sources are connected
to ground in this implementation.

Each clock mux output is exported by the CPRMAN at the qdev level,
adding the suffix '-out' to the mux name to form the output clock name.
(E.g. the 'uart' mux sees its output exported as 'uart-out' at the
CPRMAN level.)

Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Luc Michel <luc@lmichel.fr>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 151 insertions, 0 deletions

diff --git a/hw/misc/bcm2835_cprman.c b/hw/misc/bcm2835_cprman.c
index 71c1d7b9e7..b22170f3bc 100644
--- a/hw/misc/bcm2835_cprman.c
+++ b/hw/misc/bcm2835_cprman.c
@@ -38,6 +38,9 @@
  *
  * The page at https://elinux.org/The_Undocumented_Pi gives the actual clock
  * tree configuration.
+ *
+ * The CPRMAN exposes clock outputs with the name of the clock mux suffixed
+ * with "-out" (e.g. "uart-out", "h264-out", ...).
  */
 
 #include "qemu/osdep.h"
@@ -226,6 +229,65 @@ static const TypeInfo cprman_pll_channel_info = {
 };
 
 
+/* clock mux */
+
+static void clock_mux_update(CprmanClockMuxState *mux)
+{
+    clock_update(mux->out, 0);
+}
+
+static void clock_mux_src_update(void *opaque)
+{
+    CprmanClockMuxState **backref = opaque;
+    CprmanClockMuxState *s = *backref;
+
+    clock_mux_update(s);
+}
+
+static void clock_mux_init(Object *obj)
+{
+    CprmanClockMuxState *s = CPRMAN_CLOCK_MUX(obj);
+    size_t i;
+
+    for (i = 0; i < CPRMAN_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]);
+        g_free(name);
+    }
+
+    s->out = qdev_init_clock_out(DEVICE(s), "out");
+}
+
+static const VMStateDescription clock_mux_vmstate = {
+    .name = TYPE_CPRMAN_CLOCK_MUX,
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_ARRAY_CLOCK(srcs, CprmanClockMuxState,
+                            CPRMAN_NUM_CLOCK_MUX_SRC),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void clock_mux_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->vmsd = &clock_mux_vmstate;
+}
+
+static const TypeInfo cprman_clock_mux_info = {
+    .name = TYPE_CPRMAN_CLOCK_MUX,
+    .parent = TYPE_DEVICE,
+    .instance_size = sizeof(CprmanClockMuxState),
+    .class_init = clock_mux_class_init,
+    .instance_init = clock_mux_init,
+};
+
+
 /* CPRMAN "top level" model */
 
 static uint32_t get_cm_lock(const BCM2835CprmanState *s)
@@ -293,6 +355,20 @@ static inline void update_channel_from_a2w(BCM2835CprmanState *s, size_t idx)
     }
 }
 
+static inline void update_mux_from_cm(BCM2835CprmanState *s, size_t idx)
+{
+    size_t i;
+
+    for (i = 0; i < CPRMAN_NUM_CLOCK_MUX; i++) {
+        if ((CLOCK_MUX_INIT_INFO[i].cm_offset == idx) ||
+            (CLOCK_MUX_INIT_INFO[i].cm_offset + 4 == idx)) {
+            /* matches CM_CTL or CM_DIV mux register */
+            clock_mux_update(&s->clock_muxes[i]);
+            return;
+        }
+    }
+}
+
 #define CASE_PLL_A2W_REGS(pll_) \
     case R_A2W_ ## pll_ ## _CTRL: \
     case R_A2W_ ## pll_ ## _ANA0: \
@@ -365,6 +441,15 @@ static void cprman_write(void *opaque, hwaddr offset,
     case R_A2W_PLLB_ARM:
         update_channel_from_a2w(s, idx);
         break;
+
+    case R_CM_GNRICCTL ... R_CM_SMIDIV:
+    case R_CM_TCNTCNT ... R_CM_VECDIV:
+    case R_CM_PULSECTL ... R_CM_PULSEDIV:
+    case R_CM_SDCCTL ... R_CM_ARMCTL:
+    case R_CM_AVEOCTL ... R_CM_EMMCDIV:
+    case R_CM_EMMC2CTL ... R_CM_EMMC2DIV:
+        update_mux_from_cm(s, idx);
+        break;
     }
 }
 
@@ -404,6 +489,10 @@ static void cprman_reset(DeviceState *dev)
         device_cold_reset(DEVICE(&s->channels[i]));
     }
 
+    for (i = 0; i < CPRMAN_NUM_CLOCK_MUX; i++) {
+        device_cold_reset(DEVICE(&s->clock_muxes[i]));
+    }
+
     clock_update_hz(s->xosc, s->xosc_freq);
 }
 
@@ -425,13 +514,64 @@ static void cprman_init(Object *obj)
         set_pll_channel_init_info(s, &s->channels[i], i);
     }
 
+    for (i = 0; i < CPRMAN_NUM_CLOCK_MUX; i++) {
+        char *alias;
+
+        object_initialize_child(obj, CLOCK_MUX_INIT_INFO[i].name,
+                                &s->clock_muxes[i],
+                                TYPE_CPRMAN_CLOCK_MUX);
+        set_clock_mux_init_info(s, &s->clock_muxes[i], i);
+
+        /* Expose muxes output as CPRMAN outputs */
+        alias = g_strdup_printf("%s-out", CLOCK_MUX_INIT_INFO[i].name);
+        qdev_alias_clock(DEVICE(&s->clock_muxes[i]), "out", DEVICE(obj), alias);
+        g_free(alias);
+    }
+
     s->xosc = clock_new(obj, "xosc");
+    s->gnd = clock_new(obj, "gnd");
+
+    clock_set(s->gnd, 0);
 
     memory_region_init_io(&s->iomem, obj, &cprman_ops,
                           s, "bcm2835-cprman", 0x2000);
     sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->iomem);
 }
 
+static void connect_mux_sources(BCM2835CprmanState *s,
+                                CprmanClockMuxState *mux,
+                                const CprmanPllChannel *clk_mapping)
+{
+    size_t i;
+    Clock *td0 = s->clock_muxes[CPRMAN_CLOCK_TD0].out;
+    Clock *td1 = s->clock_muxes[CPRMAN_CLOCK_TD1].out;
+
+    /* For sources from 0 to 3. Source 4 to 9 are mux specific */
+    Clock * const CLK_SRC_MAPPING[] = {
+        [CPRMAN_CLOCK_SRC_GND] = s->gnd,
+        [CPRMAN_CLOCK_SRC_XOSC] = s->xosc,
+        [CPRMAN_CLOCK_SRC_TD0] = td0,
+        [CPRMAN_CLOCK_SRC_TD1] = td1,
+    };
+
+    for (i = 0; i < CPRMAN_NUM_CLOCK_MUX_SRC; i++) {
+        CprmanPllChannel mapping = clk_mapping[i];
+        Clock *src;
+
+        if (mapping == CPRMAN_CLOCK_SRC_FORCE_GROUND) {
+            src = s->gnd;
+        } else if (mapping == CPRMAN_CLOCK_SRC_DSI0HSCK) {
+            src = s->gnd; /* TODO */
+        } else if (i < CPRMAN_CLOCK_SRC_PLLA) {
+            src = CLK_SRC_MAPPING[i];
+        } else {
+            src = s->channels[mapping].out;
+        }
+
+        clock_set_source(mux->srcs[i], src);
+    }
+}
+
 static void cprman_realize(DeviceState *dev, Error **errp)
 {
     BCM2835CprmanState *s = CPRMAN(dev);
@@ -458,6 +598,16 @@ static void cprman_realize(DeviceState *dev, Error **errp)
             return;
         }
     }
+
+    for (i = 0; i < CPRMAN_NUM_CLOCK_MUX; i++) {
+        CprmanClockMuxState *clock_mux = &s->clock_muxes[i];
+
+        connect_mux_sources(s, clock_mux, CLOCK_MUX_INIT_INFO[i].src_mapping);
+
+        if (!qdev_realize(DEVICE(clock_mux), NULL, errp)) {
+            return;
+        }
+    }
 }
 
 static const VMStateDescription cprman_vmstate = {
@@ -498,6 +648,7 @@ static void cprman_register_types(void)
     type_register_static(&cprman_info);
     type_register_static(&cprman_pll_info);
     type_register_static(&cprman_pll_channel_info);
+    type_register_static(&cprman_clock_mux_info);
 }
 
 type_init(cprman_register_types);