hw/misc/aspeed: Add PECI controller

This introduces a really basic PECI controller that responses to
commands by always setting the response code to success and then raising
an interrupt to indicate the command is done. This helps avoid getting
hit with constant errors if the driver continuously attempts to send a
command and keeps timing out.

The AST2400 and AST2500 only included registers up to 0x5C, not 0xFC.
They supported PECI 1.1, 2.0, and 3.0. The AST2600 and AST1030 support
PECI 4.0, which includes more read/write buffer registers from 0x80 to
0xFC to support 64-byte mode.

This patch doesn't attempt to handle that, or to create a different
version of the controller for the different generations, since it's only
implementing functionality that is common to all generations.

The basic sequence of events is that the firmware will read and write to
various registers and then trigger a command by setting the FIRE bit in
the command register (similar to the I2C controller).

Then the firmware waits for an interrupt from the PECI controller,
expecting the interrupt status register to be filled in with info on
what happened. If the command was transmitted and received successfully,
then response codes from the host CPU will be found in the data buffer
registers.

Signed-off-by: Peter Delevoryas <pdel@fb.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20220630045133.32251-12-me@pjd.dev>
[ clg: s/sysbus_mmio_map/aspeed_mmio_map/ ]
Signed-off-by: Cédric Le Goater <clg@kaod.org>

3 files changed, 159 insertions, 1 deletions

diff --git a/hw/misc/aspeed_peci.c b/hw/misc/aspeed_peci.c
new file mode 100644
index 0000000000..93cc672e96
--- /dev/null
+++ b/hw/misc/aspeed_peci.c
@@ -0,0 +1,152 @@
+/*
+ * Aspeed PECI Controller
+ *
+ * Copyright (c) Meta Platforms, Inc. and affiliates. (http://www.meta.com)
+ *
+ * This code is licensed under the GPL version 2 or later. See the COPYING
+ * file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/log.h"
+#include "hw/irq.h"
+#include "hw/misc/aspeed_peci.h"
+#include "hw/registerfields.h"
+#include "trace.h"
+
+#define ASPEED_PECI_CC_RSP_SUCCESS (0x40U)
+
+/* Command Register */
+REG32(PECI_CMD, 0x08)
+    FIELD(PECI_CMD, FIRE, 0, 1)
+
+/* Interrupt Control Register */
+REG32(PECI_INT_CTRL, 0x18)
+
+/* Interrupt Status Register */
+REG32(PECI_INT_STS, 0x1C)
+    FIELD(PECI_INT_STS, CMD_DONE, 0, 1)
+
+/* Rx/Tx Data Buffer Registers */
+REG32(PECI_WR_DATA0, 0x20)
+REG32(PECI_RD_DATA0, 0x30)
+
+static void aspeed_peci_raise_interrupt(AspeedPECIState *s, uint32_t status)
+{
+    trace_aspeed_peci_raise_interrupt(s->regs[R_PECI_INT_CTRL], status);
+
+    s->regs[R_PECI_INT_STS] = s->regs[R_PECI_INT_CTRL] & status;
+    if (!s->regs[R_PECI_INT_STS]) {
+        return;
+    }
+    qemu_irq_raise(s->irq);
+}
+
+static uint64_t aspeed_peci_read(void *opaque, hwaddr offset, unsigned size)
+{
+    AspeedPECIState *s = ASPEED_PECI(opaque);
+    uint64_t data;
+
+    if (offset >= ASPEED_PECI_NR_REGS << 2) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: Out-of-bounds read at offset 0x%" HWADDR_PRIx "\n",
+                      __func__, offset);
+        return 0;
+    }
+    data = s->regs[offset >> 2];
+
+    trace_aspeed_peci_read(offset, data);
+    return data;
+}
+
+static void aspeed_peci_write(void *opaque, hwaddr offset, uint64_t data,
+                              unsigned size)
+{
+    AspeedPECIState *s = ASPEED_PECI(opaque);
+
+    trace_aspeed_peci_write(offset, data);
+
+    if (offset >= ASPEED_PECI_NR_REGS << 2) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: Out-of-bounds write at offset 0x%" HWADDR_PRIx "\n",
+                      __func__, offset);
+        return;
+    }
+
+    switch (offset) {
+    case A_PECI_INT_STS:
+        s->regs[R_PECI_INT_STS] &= ~data;
+        if (!s->regs[R_PECI_INT_STS]) {
+            qemu_irq_lower(s->irq);
+        }
+        break;
+    case A_PECI_CMD:
+        /*
+         * Only the FIRE bit is writable. Once the command is complete, it
+         * should be cleared. Since we complete the command immediately, the
+         * value is not stored in the register array.
+         */
+        if (!FIELD_EX32(data, PECI_CMD, FIRE)) {
+            break;
+        }
+        if (s->regs[R_PECI_INT_STS]) {
+            qemu_log_mask(LOG_GUEST_ERROR, "%s: Interrupt status must be "
+                          "cleared before firing another command: 0x%08x\n",
+                          __func__, s->regs[R_PECI_INT_STS]);
+            break;
+        }
+        s->regs[R_PECI_RD_DATA0] = ASPEED_PECI_CC_RSP_SUCCESS;
+        s->regs[R_PECI_WR_DATA0] = ASPEED_PECI_CC_RSP_SUCCESS;
+        aspeed_peci_raise_interrupt(s,
+                                    FIELD_DP32(0, PECI_INT_STS, CMD_DONE, 1));
+        break;
+    default:
+        s->regs[offset / sizeof(s->regs[0])] = data;
+        break;
+    }
+}
+
+static const MemoryRegionOps aspeed_peci_ops = {
+    .read = aspeed_peci_read,
+    .write = aspeed_peci_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+};
+
+static void aspeed_peci_realize(DeviceState *dev, Error **errp)
+{
+    AspeedPECIState *s = ASPEED_PECI(dev);
+    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
+
+    memory_region_init_io(&s->mmio, OBJECT(s), &aspeed_peci_ops, s,
+                          TYPE_ASPEED_PECI, 0x1000);
+    sysbus_init_mmio(sbd, &s->mmio);
+    sysbus_init_irq(sbd, &s->irq);
+}
+
+static void aspeed_peci_reset(DeviceState *dev)
+{
+    AspeedPECIState *s = ASPEED_PECI(dev);
+
+    memset(s->regs, 0, sizeof(s->regs));
+}
+
+static void aspeed_peci_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->realize = aspeed_peci_realize;
+    dc->reset = aspeed_peci_reset;
+    dc->desc = "Aspeed PECI Controller";
+}
+
+static const TypeInfo aspeed_peci_types[] = {
+    {
+        .name = TYPE_ASPEED_PECI,
+        .parent = TYPE_SYS_BUS_DEVICE,
+        .instance_size = sizeof(AspeedPECIState),
+        .class_init = aspeed_peci_class_init,
+        .abstract = false,
+    },
+};
+
+DEFINE_TYPES(aspeed_peci_types);
diff --git a/hw/misc/meson.build b/hw/misc/meson.build
index 132b7b7344..95268eddc0 100644
--- a/hw/misc/meson.build
+++ b/hw/misc/meson.build
@@ -116,7 +116,8 @@ softmmu_ss.add(when: 'CONFIG_ASPEED_SOC', if_true: files(
   'aspeed_scu.c',
   'aspeed_sbc.c',
   'aspeed_sdmc.c',
-  'aspeed_xdma.c'))
+  'aspeed_xdma.c',
+  'aspeed_peci.c'))
 
 softmmu_ss.add(when: 'CONFIG_MSF2', if_true: files('msf2-sysreg.c'))
 softmmu_ss.add(when: 'CONFIG_NRF51_SOC', if_true: files('nrf51_rng.c'))
diff --git a/hw/misc/trace-events b/hw/misc/trace-events
index f776f24fb5..4d51a80de1 100644
--- a/hw/misc/trace-events
+++ b/hw/misc/trace-events
@@ -210,6 +210,11 @@ aspeed_i3c_device_write(uint32_t deviceid, uint64_t offset, uint64_t data) "I3C
 aspeed_sdmc_write(uint64_t reg, uint64_t data) "reg @0x%" PRIx64 " data: 0x%" PRIx64
 aspeed_sdmc_read(uint64_t reg, uint64_t data) "reg @0x%" PRIx64 " data: 0x%" PRIx64
 
+# aspeed_peci.c
+aspeed_peci_read(uint64_t offset, uint64_t data) "offset 0x%" PRIx64 " data 0x%" PRIx64
+aspeed_peci_write(uint64_t offset, uint64_t data) "offset 0x%" PRIx64 " data 0x%" PRIx64
+aspeed_peci_raise_interrupt(uint32_t ctrl, uint32_t status) "ctrl 0x%" PRIx32 " status 0x%" PRIx32
+
 # bcm2835_property.c
 bcm2835_mbox_property(uint32_t tag, uint32_t bufsize, size_t resplen) "mbox property tag:0x%08x in_sz:%u out_sz:%zu"