Merge remote-tracking branch 'remotes/cminyard/tags/for-qemu-6.1-v1' into staging

Add a bus multiplexer device

This patch set adds a bus multiplexer and the necessary infrastructure
in the I2C code to allow it to work.

These are common on systems with lots of I2C devices, like an IPMI BMC.

# gpg: Signature made Thu 13 May 2021 22:48:07 BST
# gpg:                using RSA key FD0D5CE67CE0F59A6688268661F38C90919BFF81
# gpg: Good signature from "Corey Minyard <cminyard@mvista.com>" [unknown]
# gpg:                 aka "Corey Minyard <minyard@acm.org>" [unknown]
# gpg:                 aka "Corey Minyard <corey@minyard.net>" [unknown]
# gpg:                 aka "Corey Minyard <minyard@mvista.com>" [unknown]
# gpg: WARNING: This key is not certified with a trusted signature!
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# Primary key fingerprint: FD0D 5CE6 7CE0 F59A 6688  2686 61F3 8C90 919B FF81

* remotes/cminyard/tags/for-qemu-6.1-v1:
  hw/i2c: add pca954x i2c-mux switch
  hw/i2c: move search to i2c_scan_bus method
  hw/i2c: add match method for device search
  hw/i2c: name I2CNode list in I2CBus

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

5 files changed, 342 insertions, 13 deletions

diff --git a/hw/i2c/Kconfig b/hw/i2c/Kconfig
index 09642a6dcb..8d120a25d5 100644
--- a/hw/i2c/Kconfig
+++ b/hw/i2c/Kconfig
@@ -28,3 +28,7 @@ config IMX_I2C
 config MPC_I2C
     bool
     select I2C
+
+config PCA954X
+    bool
+    select I2C
diff --git a/hw/i2c/core.c b/hw/i2c/core.c
index 21ec52ac5a..3a7bae311d 100644
--- a/hw/i2c/core.c
+++ b/hw/i2c/core.c
@@ -77,6 +77,30 @@ int i2c_bus_busy(I2CBus *bus)
     return !QLIST_EMPTY(&bus->current_devs);
 }
 
+bool i2c_scan_bus(I2CBus *bus, uint8_t address, bool broadcast,
+                  I2CNodeList *current_devs)
+{
+    BusChild *kid;
+
+    QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
+        DeviceState *qdev = kid->child;
+        I2CSlave *candidate = I2C_SLAVE(qdev);
+        I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(candidate);
+
+        if (sc->match_and_add(candidate, address, broadcast, current_devs)) {
+            if (!broadcast) {
+                return true;
+            }
+        }
+    }
+
+    /*
+     * If broadcast was true, and the list was full or empty, return true. If
+     * broadcast was false, return false.
+     */
+    return broadcast;
+}
+
 /* TODO: Make this handle multiple masters.  */
 /*
  * Start or continue an i2c transaction.  When this is called for the
@@ -93,7 +117,6 @@ int i2c_bus_busy(I2CBus *bus)
  */
 int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv)
 {
-    BusChild *kid;
     I2CSlaveClass *sc;
     I2CNode *node;
     bool bus_scanned = false;
@@ -115,18 +138,8 @@ int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv)
      * terminating the previous transaction.
      */
     if (QLIST_EMPTY(&bus->current_devs)) {
-        QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
-            DeviceState *qdev = kid->child;
-            I2CSlave *candidate = I2C_SLAVE(qdev);
-            if ((candidate->address == address) || (bus->broadcast)) {
-                node = g_malloc(sizeof(struct I2CNode));
-                node->elt = candidate;
-                QLIST_INSERT_HEAD(&bus->current_devs, node, next);
-                if (!bus->broadcast) {
-                    break;
-                }
-            }
-        }
+        /* Disregard whether devices were found. */
+        (void)i2c_scan_bus(bus, address, bus->broadcast, &bus->current_devs);
         bus_scanned = true;
     }
 
@@ -290,12 +303,28 @@ I2CSlave *i2c_slave_create_simple(I2CBus *bus, const char *name, uint8_t addr)
     return dev;
 }
 
+static bool i2c_slave_match(I2CSlave *candidate, uint8_t address,
+                            bool broadcast, I2CNodeList *current_devs)
+{
+    if ((candidate->address == address) || (broadcast)) {
+        I2CNode *node = g_malloc(sizeof(struct I2CNode));
+        node->elt = candidate;
+        QLIST_INSERT_HEAD(current_devs, node, next);
+        return true;
+    }
+
+    /* Not found and not broadcast. */
+    return false;
+}
+
 static void i2c_slave_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *k = DEVICE_CLASS(klass);
+    I2CSlaveClass *sc = I2C_SLAVE_CLASS(klass);
     set_bit(DEVICE_CATEGORY_MISC, k->categories);
     k->bus_type = TYPE_I2C_BUS;
     device_class_set_props(k, i2c_props);
+    sc->match_and_add = i2c_slave_match;
 }
 
 static const TypeInfo i2c_slave_type_info = {
diff --git a/hw/i2c/i2c_mux_pca954x.c b/hw/i2c/i2c_mux_pca954x.c
new file mode 100644
index 0000000000..847c59921c
--- /dev/null
+++ b/hw/i2c/i2c_mux_pca954x.c
@@ -0,0 +1,290 @@
+/*
+ * I2C multiplexer for PCA954x series of I2C multiplexer/switch chips.
+ *
+ * Copyright 2021 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 "qapi/error.h"
+#include "hw/i2c/i2c.h"
+#include "hw/i2c/i2c_mux_pca954x.h"
+#include "hw/i2c/smbus_slave.h"
+#include "hw/qdev-core.h"
+#include "hw/sysbus.h"
+#include "qemu/log.h"
+#include "qemu/module.h"
+#include "qemu/queue.h"
+#include "qom/object.h"
+#include "trace.h"
+
+#define PCA9548_CHANNEL_COUNT 8
+#define PCA9546_CHANNEL_COUNT 4
+
+/*
+ * struct Pca954xChannel - The i2c mux device will have N of these states
+ * that own the i2c channel bus.
+ * @bus: The owned channel bus.
+ * @enabled: Is this channel active?
+ */
+typedef struct Pca954xChannel {
+    SysBusDevice parent;
+
+    I2CBus       *bus;
+
+    bool         enabled;
+} Pca954xChannel;
+
+#define TYPE_PCA954X_CHANNEL "pca954x-channel"
+#define PCA954X_CHANNEL(obj) \
+    OBJECT_CHECK(Pca954xChannel, (obj), TYPE_PCA954X_CHANNEL)
+
+/*
+ * struct Pca954xState - The pca954x state object.
+ * @control: The value written to the mux control.
+ * @channel: The set of i2c channel buses that act as channels which own the
+ * i2c children.
+ */
+typedef struct Pca954xState {
+    SMBusDevice parent;
+
+    uint8_t control;
+
+    /* The channel i2c buses. */
+    Pca954xChannel channel[PCA9548_CHANNEL_COUNT];
+} Pca954xState;
+
+/*
+ * struct Pca954xClass - The pca954x class object.
+ * @nchans: The number of i2c channels this device has.
+ */
+typedef struct Pca954xClass {
+    SMBusDeviceClass parent;
+
+    uint8_t nchans;
+} Pca954xClass;
+
+#define TYPE_PCA954X "pca954x"
+OBJECT_DECLARE_TYPE(Pca954xState, Pca954xClass, PCA954X)
+
+/*
+ * For each channel, if it's enabled, recursively call match on those children.
+ */
+static bool pca954x_match(I2CSlave *candidate, uint8_t address,
+                          bool broadcast,
+                          I2CNodeList *current_devs)
+{
+    Pca954xState *mux = PCA954X(candidate);
+    Pca954xClass *mc = PCA954X_GET_CLASS(mux);
+    int i;
+
+    /* They are talking to the mux itself (or all devices enabled). */
+    if ((candidate->address == address) || broadcast) {
+        I2CNode *node = g_malloc(sizeof(struct I2CNode));
+        node->elt = candidate;
+        QLIST_INSERT_HEAD(current_devs, node, next);
+        if (!broadcast) {
+            return true;
+        }
+    }
+
+    for (i = 0; i < mc->nchans; i++) {
+        if (!mux->channel[i].enabled) {
+            continue;
+        }
+
+        if (i2c_scan_bus(mux->channel[i].bus, address, broadcast,
+                         current_devs)) {
+            if (!broadcast) {
+                return true;
+            }
+        }
+    }
+
+    /* If we arrived here we didn't find a match, return broadcast. */
+    return broadcast;
+}
+
+static void pca954x_enable_channel(Pca954xState *s, uint8_t enable_mask)
+{
+    Pca954xClass *mc = PCA954X_GET_CLASS(s);
+    int i;
+
+    /*
+     * For each channel, check if their bit is set in enable_mask and if yes,
+     * enable it, otherwise disable, hide it.
+     */
+    for (i = 0; i < mc->nchans; i++) {
+        if (enable_mask & (1 << i)) {
+            s->channel[i].enabled = true;
+        } else {
+            s->channel[i].enabled = false;
+        }
+    }
+}
+
+static void pca954x_write(Pca954xState *s, uint8_t data)
+{
+    s->control = data;
+    pca954x_enable_channel(s, data);
+
+    trace_pca954x_write_bytes(data);
+}
+
+static int pca954x_write_data(SMBusDevice *d, uint8_t *buf, uint8_t len)
+{
+    Pca954xState *s = PCA954X(d);
+
+    if (len == 0) {
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: writing empty data\n", __func__);
+        return -1;
+    }
+
+    /*
+     * len should be 1, because they write one byte to enable/disable channels.
+     */
+    if (len > 1) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+            "%s: extra data after channel selection mask\n",
+            __func__);
+        return -1;
+    }
+
+    pca954x_write(s, buf[0]);
+    return 0;
+}
+
+static uint8_t pca954x_read_byte(SMBusDevice *d)
+{
+    Pca954xState *s = PCA954X(d);
+    uint8_t data = s->control;
+    trace_pca954x_read_data(data);
+    return data;
+}
+
+static void pca954x_enter_reset(Object *obj, ResetType type)
+{
+    Pca954xState *s = PCA954X(obj);
+    /* Reset will disable all channels. */
+    pca954x_write(s, 0);
+}
+
+I2CBus *pca954x_i2c_get_bus(I2CSlave *mux, uint8_t channel)
+{
+    Pca954xClass *pc = PCA954X_GET_CLASS(mux);
+    Pca954xState *pca954x = PCA954X(mux);
+
+    g_assert(channel < pc->nchans);
+    return I2C_BUS(qdev_get_child_bus(DEVICE(&pca954x->channel[channel]),
+                                      "i2c-bus"));
+}
+
+static void pca954x_channel_init(Object *obj)
+{
+    Pca954xChannel *s = PCA954X_CHANNEL(obj);
+    s->bus = i2c_init_bus(DEVICE(s), "i2c-bus");
+
+    /* Start all channels as disabled. */
+    s->enabled = false;
+}
+
+static void pca954x_channel_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    dc->desc = "Pca954x Channel";
+}
+
+static void pca9546_class_init(ObjectClass *klass, void *data)
+{
+    Pca954xClass *s = PCA954X_CLASS(klass);
+    s->nchans = PCA9546_CHANNEL_COUNT;
+}
+
+static void pca9548_class_init(ObjectClass *klass, void *data)
+{
+    Pca954xClass *s = PCA954X_CLASS(klass);
+    s->nchans = PCA9548_CHANNEL_COUNT;
+}
+
+static void pca954x_realize(DeviceState *dev, Error **errp)
+{
+    Pca954xState *s = PCA954X(dev);
+    Pca954xClass *c = PCA954X_GET_CLASS(s);
+    int i;
+
+    /* SMBus modules. Cannot fail. */
+    for (i = 0; i < c->nchans; i++) {
+        sysbus_realize(SYS_BUS_DEVICE(&s->channel[i]), &error_abort);
+    }
+}
+
+static void pca954x_init(Object *obj)
+{
+    Pca954xState *s = PCA954X(obj);
+    Pca954xClass *c = PCA954X_GET_CLASS(obj);
+    int i;
+
+    /* Only initialize the children we expect. */
+    for (i = 0; i < c->nchans; i++) {
+        object_initialize_child(obj, "channel[*]", &s->channel[i],
+                                TYPE_PCA954X_CHANNEL);
+    }
+}
+
+static void pca954x_class_init(ObjectClass *klass, void *data)
+{
+    I2CSlaveClass *sc = I2C_SLAVE_CLASS(klass);
+    ResettableClass *rc = RESETTABLE_CLASS(klass);
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    SMBusDeviceClass *k = SMBUS_DEVICE_CLASS(klass);
+
+    sc->match_and_add = pca954x_match;
+
+    rc->phases.enter = pca954x_enter_reset;
+
+    dc->desc = "Pca954x i2c-mux";
+    dc->realize = pca954x_realize;
+
+    k->write_data = pca954x_write_data;
+    k->receive_byte = pca954x_read_byte;
+}
+
+static const TypeInfo pca954x_info[] = {
+    {
+        .name          = TYPE_PCA954X,
+        .parent        = TYPE_SMBUS_DEVICE,
+        .instance_size = sizeof(Pca954xState),
+        .instance_init = pca954x_init,
+        .class_size    = sizeof(Pca954xClass),
+        .class_init    = pca954x_class_init,
+        .abstract      = true,
+    },
+    {
+        .name          = TYPE_PCA9546,
+        .parent        = TYPE_PCA954X,
+        .class_init    = pca9546_class_init,
+    },
+    {
+        .name          = TYPE_PCA9548,
+        .parent        = TYPE_PCA954X,
+        .class_init    = pca9548_class_init,
+    },
+    {
+        .name = TYPE_PCA954X_CHANNEL,
+        .parent = TYPE_SYS_BUS_DEVICE,
+        .class_init = pca954x_channel_class_init,
+        .instance_size = sizeof(Pca954xChannel),
+        .instance_init = pca954x_channel_init,
+    }
+};
+
+DEFINE_TYPES(pca954x_info)
diff --git a/hw/i2c/meson.build b/hw/i2c/meson.build
index cdcd694a7f..dd3aef02b2 100644
--- a/hw/i2c/meson.build
+++ b/hw/i2c/meson.build
@@ -14,4 +14,5 @@ i2c_ss.add(when: 'CONFIG_SMBUS_EEPROM', if_true: files('smbus_eeprom.c'))
 i2c_ss.add(when: 'CONFIG_VERSATILE_I2C', if_true: files('versatile_i2c.c'))
 i2c_ss.add(when: 'CONFIG_OMAP', if_true: files('omap_i2c.c'))
 i2c_ss.add(when: 'CONFIG_PPC4XX', if_true: files('ppc4xx_i2c.c'))
+i2c_ss.add(when: 'CONFIG_PCA954X', if_true: files('i2c_mux_pca954x.c'))
 softmmu_ss.add_all(when: 'CONFIG_I2C', if_true: i2c_ss)
diff --git a/hw/i2c/trace-events b/hw/i2c/trace-events
index 82fe6f965f..82f19e6a2d 100644
--- a/hw/i2c/trace-events
+++ b/hw/i2c/trace-events
@@ -26,3 +26,8 @@ npcm7xx_smbus_recv_byte(const char *id, uint8_t value) "%s recv byte: 0x%02x"
 npcm7xx_smbus_stop(const char *id) "%s stopping"
 npcm7xx_smbus_nack(const char *id) "%s nacking"
 npcm7xx_smbus_recv_fifo(const char *id, uint8_t received, uint8_t expected) "%s recv fifo: received %u, expected %u"
+
+# i2c-mux-pca954x.c
+
+pca954x_write_bytes(uint8_t value) "PCA954X write data: 0x%02x"
+pca954x_read_data(uint8_t value) "PCA954X read data: 0x%02x"