[PATCH v6 02/13] hw/misc: Add NPCM7xx Clock Controller device model

[Havard Skinnemoen <hskinnemoen@google.com>]

Enough functionality to boot the Linux kernel has been implemented. This
includes:

  - Correct power-on reset values so the various clock rates can be
    accurately calculated.
  - Clock enables stick around when written.

In addition, a best effort attempt to implement SECCNT and CNTR25M was
made even though I don't think the kernel needs them.

Reviewed-by: Tyrone Ting <kfting@nuvoton.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Havard Skinnemoen <hskinnemoen@google.com>
---
 include/hw/misc/npcm7xx_clk.h |  72 +++++++++++
 hw/misc/npcm7xx_clk.c         | 234 ++++++++++++++++++++++++++++++++++
 hw/misc/Makefile.objs         |   1 +
 hw/misc/trace-events          |   4 +
 4 files changed, 311 insertions(+)
 create mode 100644 include/hw/misc/npcm7xx_clk.h
 create mode 100644 hw/misc/npcm7xx_clk.c

diff --git a/include/hw/misc/npcm7xx_clk.h b/include/hw/misc/npcm7xx_clk.h
new file mode 100644
index 0000000000..40ed64ff15
--- /dev/null
+++ b/include/hw/misc/npcm7xx_clk.h
@@ -0,0 +1,72 @@
+/*
+ * Nuvoton NPCM7xx Clock Control Registers.
+ *
+ * Copyright 2020 Google LLC
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ */
+#ifndef NPCM7XX_CLK_H
+#define NPCM7XX_CLK_H
+
+#include "exec/memory.h"
+#include "hw/sysbus.h"
+
+/*
+ * The reference clock frequency for the timer modules, and the SECCNT and
+ * CNTR25M registers in this module, is always 25 MHz.
+ */
+#define NPCM7XX_TIMER_REF_HZ            (25000000)
+
+enum NPCM7xxCLKRegisters {
+    NPCM7XX_CLK_CLKEN1,
+    NPCM7XX_CLK_CLKSEL,
+    NPCM7XX_CLK_CLKDIV1,
+    NPCM7XX_CLK_PLLCON0,
+    NPCM7XX_CLK_PLLCON1,
+    NPCM7XX_CLK_SWRSTR,
+    NPCM7XX_CLK_IPSRST1         = 0x20 / sizeof(uint32_t),
+    NPCM7XX_CLK_IPSRST2,
+    NPCM7XX_CLK_CLKEN2,
+    NPCM7XX_CLK_CLKDIV2,
+    NPCM7XX_CLK_CLKEN3,
+    NPCM7XX_CLK_IPSRST3,
+    NPCM7XX_CLK_WD0RCR,
+    NPCM7XX_CLK_WD1RCR,
+    NPCM7XX_CLK_WD2RCR,
+    NPCM7XX_CLK_SWRSTC1,
+    NPCM7XX_CLK_SWRSTC2,
+    NPCM7XX_CLK_SWRSTC3,
+    NPCM7XX_CLK_SWRSTC4,
+    NPCM7XX_CLK_PLLCON2,
+    NPCM7XX_CLK_CLKDIV3,
+    NPCM7XX_CLK_CORSTC,
+    NPCM7XX_CLK_PLLCONG,
+    NPCM7XX_CLK_AHBCKFI,
+    NPCM7XX_CLK_SECCNT,
+    NPCM7XX_CLK_CNTR25M,
+    NPCM7XX_CLK_NR_REGS,
+};
+
+typedef struct NPCM7xxCLKState {
+    SysBusDevice parent;
+
+    MemoryRegion iomem;
+
+    uint32_t regs[NPCM7XX_CLK_NR_REGS];
+
+    /* Time reference for SECCNT and CNTR25M, initialized by power on reset */
+    int64_t ref_ns;
+} NPCM7xxCLKState;
+
+#define TYPE_NPCM7XX_CLK "npcm7xx-clk"
+#define NPCM7XX_CLK(obj) OBJECT_CHECK(NPCM7xxCLKState, (obj), TYPE_NPCM7XX_CLK)
+
+#endif /* NPCM7XX_CLK_H */
diff --git a/hw/misc/npcm7xx_clk.c b/hw/misc/npcm7xx_clk.c
new file mode 100644
index 0000000000..55beecc06f
--- /dev/null
+++ b/hw/misc/npcm7xx_clk.c
@@ -0,0 +1,234 @@
+/*
+ * Nuvoton NPCM7xx Clock Control Registers.
+ *
+ * Copyright 2020 Google LLC
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ */
+
+#include "qemu/osdep.h"
+
+#include "hw/misc/npcm7xx_clk.h"
+#include "migration/vmstate.h"
+#include "qemu/error-report.h"
+#include "qemu/log.h"
+#include "qemu/module.h"
+#include "qemu/timer.h"
+#include "qemu/units.h"
+#include "trace.h"
+
+#define PLLCON_LOKI     BIT(31)
+#define PLLCON_LOKS     BIT(30)
+#define PLLCON_PWDEN    BIT(12)
+
+/*
+ * These reset values were taken from version 0.91 of the NPCM750R data sheet.
+ *
+ * All are loaded on power-up reset. CLKENx and SWRSTR should also be loaded on
+ * core domain reset, but this reset type is not yet supported by QEMU.
+ */
+static const uint32_t cold_reset_values[NPCM7XX_CLK_NR_REGS] = {
+    [NPCM7XX_CLK_CLKEN1]        = 0xffffffff,
+    [NPCM7XX_CLK_CLKSEL]        = 0x004aaaaa,
+    [NPCM7XX_CLK_CLKDIV1]       = 0x5413f855,
+    [NPCM7XX_CLK_PLLCON0]       = 0x00222101 | PLLCON_LOKI,
+    [NPCM7XX_CLK_PLLCON1]       = 0x00202101 | PLLCON_LOKI,
+    [NPCM7XX_CLK_IPSRST1]       = 0x00001000,
+    [NPCM7XX_CLK_IPSRST2]       = 0x80000000,
+    [NPCM7XX_CLK_CLKEN2]        = 0xffffffff,
+    [NPCM7XX_CLK_CLKDIV2]       = 0xaa4f8f9f,
+    [NPCM7XX_CLK_CLKEN3]        = 0xffffffff,
+    [NPCM7XX_CLK_IPSRST3]       = 0x03000000,
+    [NPCM7XX_CLK_WD0RCR]        = 0xffffffff,
+    [NPCM7XX_CLK_WD1RCR]        = 0xffffffff,
+    [NPCM7XX_CLK_WD2RCR]        = 0xffffffff,
+    [NPCM7XX_CLK_SWRSTC1]       = 0x00000003,
+    [NPCM7XX_CLK_PLLCON2]       = 0x00c02105 | PLLCON_LOKI,
+    [NPCM7XX_CLK_CORSTC]        = 0x04000003,
+    [NPCM7XX_CLK_PLLCONG]       = 0x01228606 | PLLCON_LOKI,
+    [NPCM7XX_CLK_AHBCKFI]       = 0x000000c8,
+};
+
+static uint64_t npcm7xx_clk_read(void *opaque, hwaddr offset, unsigned size)
+{
+    uint32_t reg = offset / sizeof(uint32_t);
+    NPCM7xxCLKState *s = opaque;
+    int64_t now_ns;
+    uint32_t value = 0;
+
+    if (reg >= NPCM7XX_CLK_NR_REGS) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: offset 0x%04" HWADDR_PRIx " out of range\n",
+                      __func__, offset);
+        return 0;
+    }
+
+    switch (reg) {
+    case NPCM7XX_CLK_SWRSTR:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: register @ 0x%04" HWADDR_PRIx " is write-only\n",
+                      __func__, offset);
+        break;
+
+    case NPCM7XX_CLK_SECCNT:
+        now_ns = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+        value = (now_ns - s->ref_ns) / NANOSECONDS_PER_SECOND;
+        break;
+
+    case NPCM7XX_CLK_CNTR25M:
+        now_ns = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+        /*
+         * This register counts 25 MHz cycles, updating every 640 ns. It rolls
+         * over to zero every second.
+         *
+         * The 4 LSBs are always zero: (1e9 / 640) << 4 = 25000000.
+         */
+        value = (((now_ns - s->ref_ns) / 640) << 4) % NPCM7XX_TIMER_REF_HZ;
+        break;
+
+    default:
+        value = s->regs[reg];
+        break;
+    };
+
+    trace_npcm7xx_clk_read(offset, value);
+
+    return value;
+}
+
+static void npcm7xx_clk_write(void *opaque, hwaddr offset,
+                              uint64_t v, unsigned size)
+{
+    uint32_t reg = offset / sizeof(uint32_t);
+    NPCM7xxCLKState *s = opaque;
+    uint32_t value = v;
+
+    trace_npcm7xx_clk_write(offset, value);
+
+    if (reg >= NPCM7XX_CLK_NR_REGS) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: offset 0x%04" HWADDR_PRIx " out of range\n",
+                      __func__, offset);
+        return;
+    }
+
+    switch (reg) {
+    case NPCM7XX_CLK_SWRSTR:
+        qemu_log_mask(LOG_UNIMP, "%s: SW reset not implemented: 0x%02x\n",
+                      __func__, value);
+        value = 0;
+        break;
+
+    case NPCM7XX_CLK_PLLCON0:
+    case NPCM7XX_CLK_PLLCON1:
+    case NPCM7XX_CLK_PLLCON2:
+    case NPCM7XX_CLK_PLLCONG:
+        if (value & PLLCON_PWDEN) {
+            /* Power down -- clear lock and indicate loss of lock */
+            value &= ~PLLCON_LOKI;
+            value |= PLLCON_LOKS;
+        } else {
+            /* Normal mode -- assume always locked */
+            value |= PLLCON_LOKI;
+            /* Keep LOKS unchanged unless cleared by writing 1 */
+            if (value & PLLCON_LOKS) {
+                value &= ~PLLCON_LOKS;
+            } else {
+                value |= (value & PLLCON_LOKS);
+            }
+        }
+        break;
+
+    case NPCM7XX_CLK_CNTR25M:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: register @ 0x%04" HWADDR_PRIx " is read-only\n",
+                      __func__, offset);
+        return;
+    }
+
+    s->regs[reg] = value;
+}
+
+static const struct MemoryRegionOps npcm7xx_clk_ops = {
+    .read       = npcm7xx_clk_read,
+    .write      = npcm7xx_clk_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+    .valid      = {
+        .min_access_size        = 4,
+        .max_access_size        = 4,
+        .unaligned              = false,
+    },
+};
+
+static void npcm7xx_clk_enter_reset(Object *obj, ResetType type)
+{
+    NPCM7xxCLKState *s = NPCM7XX_CLK(obj);
+
+    QEMU_BUILD_BUG_ON(sizeof(s->regs) != sizeof(cold_reset_values));
+
+    switch (type) {
+    case RESET_TYPE_COLD:
+        memcpy(s->regs, cold_reset_values, sizeof(cold_reset_values));
+        s->ref_ns = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+        return;
+    }
+
+    /*
+     * A small number of registers need to be reset on a core domain reset,
+     * but no such reset type exists yet.
+     */
+    qemu_log_mask(LOG_UNIMP, "%s: reset type %d not implemented.",
+                  __func__, type);
+}
+
+static void npcm7xx_clk_init(Object *obj)
+{
+    NPCM7xxCLKState *s = NPCM7XX_CLK(obj);
+
+    memory_region_init_io(&s->iomem, obj, &npcm7xx_clk_ops, s,
+                          TYPE_NPCM7XX_CLK, 4 * KiB);
+    sysbus_init_mmio(&s->parent, &s->iomem);
+}
+
+static const VMStateDescription vmstate_npcm7xx_clk = {
+    .name = "npcm7xx-clk",
+    .version_id = 0,
+    .minimum_version_id = 0,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32_ARRAY(regs, NPCM7xxCLKState, NPCM7XX_CLK_NR_REGS),
+        VMSTATE_INT64(ref_ns, NPCM7xxCLKState),
+        VMSTATE_END_OF_LIST(),
+    },
+};
+
+static void npcm7xx_clk_class_init(ObjectClass *klass, void *data)
+{
+    ResettableClass *rc = RESETTABLE_CLASS(klass);
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->desc = "NPCM7xx Clock Control Registers";
+    dc->vmsd = &vmstate_npcm7xx_clk;
+    rc->phases.enter = npcm7xx_clk_enter_reset;
+}
+
+static const TypeInfo npcm7xx_clk_info = {
+    .name               = TYPE_NPCM7XX_CLK,
+    .parent             = TYPE_SYS_BUS_DEVICE,
+    .instance_size      = sizeof(NPCM7xxCLKState),
+    .instance_init      = npcm7xx_clk_init,
+    .class_init         = npcm7xx_clk_class_init,
+};
+
+static void npcm7xx_clk_register_type(void)
+{
+    type_register_static(&npcm7xx_clk_info);
+}
+type_init(npcm7xx_clk_register_type);
diff --git a/hw/misc/Makefile.objs b/hw/misc/Makefile.objs
index e00b839f03..9a73c1f77f 100644
--- a/hw/misc/Makefile.objs
+++ b/hw/misc/Makefile.objs
@@ -51,6 +51,7 @@ common-obj-$(CONFIG_IMX) += imx_rngc.o
 common-obj-$(CONFIG_MILKYMIST) += milkymist-hpdmc.o
 common-obj-$(CONFIG_MILKYMIST) += milkymist-pfpu.o
 common-obj-$(CONFIG_MAINSTONE) += mst_fpga.o
+common-obj-$(CONFIG_NPCM7XX) += npcm7xx_clk.o
 common-obj-$(CONFIG_NPCM7XX) += npcm7xx_gcr.o
 common-obj-$(CONFIG_OMAP) += omap_clk.o
 common-obj-$(CONFIG_OMAP) += omap_gpmc.o
diff --git a/hw/misc/trace-events b/hw/misc/trace-events
index dbf90db8ed..a010699b4f 100644
--- a/hw/misc/trace-events
+++ b/hw/misc/trace-events
@@ -111,6 +111,10 @@ mos6522_set_sr_int(void) "set sr_int"
 mos6522_write(uint64_t addr, uint64_t val) "reg=0x%"PRIx64 " val=0x%"PRIx64
 mos6522_read(uint64_t addr, unsigned val) "reg=0x%"PRIx64 " val=0x%x"
 
+# npcm7xx_clk.c
+npcm7xx_clk_read(uint64_t offset, uint32_t value) " offset: 0x%04" PRIx64 " value: 0x%08" PRIx32
+npcm7xx_clk_write(uint64_t offset, uint32_t value) "offset: 0x%04" PRIx64 " value: 0x%08" PRIx32
+
 # npcm7xx_gcr.c
 npcm7xx_gcr_read(uint64_t offset, uint32_t value) " offset: 0x%04" PRIx64 " value: 0x%08" PRIx32
 npcm7xx_gcr_write(uint64_t offset, uint32_t value) "offset: 0x%04" PRIx64 " value: 0x%08" PRIx32
-- 
2.28.0.rc0.105.gf9edc3c819-goog