hw/i2c/i2c_mux_pca954x.c - qemu - Git at Google

 /*
  * 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)
	/*
	* 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)