drivers: i3c: i3c_dw: dynamically attach I2C devices on transfer

The maximum number of attached devices is limited by the maximum
number of entries in the device address table. For I3C devices
these have to by allocated permanently when devices are attached
but for I2C devices we can dynamically allocate an entry in the
table on a I2C transfer and free it after the transfer is completed.
This allows the maximum number of I2C + I3C devices on a bus to be
larger than the address table size as long as the number of I3C
devices is maxdevs - 1.

Signed-off-by: Corey Wharton <[email protected]>

Author: xodus7

drivers/i3c/i3c_dw.c

@@ -672,33 +672,6 @@ static int get_i3c_addr_pos(const struct device *dev, uint8_t addr, bool sa)
 	return dw_i3c_device_data->id;
 }
 
-/**
- * @brief Get the position of an I2C device with the specified address.
- *
- * This function retrieves the position (ID) of an I2C device with the specified
- * address on the I3C bus associated with the provided I3C device structure. This
- * utilizes the controller private data for where the id reg is stored.
- *
- * @param dev Pointer to the I3C device structure.
- * @param addr I2C address of the device whose position is to be retrieved.
- *
- * @return The position (ID) of the device on success, or a negative error code
- *         if the device with the given address is not found.
- */
-static int get_i2c_addr_pos(const struct device *dev, uint16_t addr)
-{
-	struct dw_i3c_i2c_dev_data *dw_i3c_device_data;
-	struct i3c_i2c_device_desc *desc = i3c_dev_list_i2c_addr_find(dev, addr);
-
-	if (desc == NULL) {
-		return -ENODEV;
-	}
-
-	dw_i3c_device_data = desc->controller_priv;
-
-	return dw_i3c_device_data->id;
-}
-
 /**
  * @brief Transfer messages in I3C mode.
  *
@@ -891,6 +864,41 @@ static int dw_i3c_xfers(const struct device *dev, struct i3c_device_desc *target
 	return ret;
 }
 
+static int dw_i3c_i2c_attach_device(const struct device *dev, struct i3c_i2c_device_desc *desc)
+{
+	const struct dw_i3c_config *config = dev->config;
+	struct dw_i3c_data *data = dev->data;
+	uint8_t pos;
+
+	pos = get_free_pos(data->free_pos);
+	if (pos < 0) {
+		return -ENOSPC;
+	}
+
+	data->dw_i3c_i2c_priv_data[pos].id = pos;
+	desc->controller_priv = &(data->dw_i3c_i2c_priv_data[pos]);
+	data->free_pos &= ~BIT(pos);
+
+	sys_write32(DEV_ADDR_TABLE_LEGACY_I2C_DEV | DEV_ADDR_TABLE_STATIC_ADDR(desc->addr),
+		    config->regs + DEV_ADDR_TABLE_LOC(data->datstartaddr, pos));
+
+	return 0;
+}
+
+static void dw_i3c_i2c_detach_device(const struct device *dev, struct i3c_i2c_device_desc *desc)
+{
+	const struct dw_i3c_config *config = dev->config;
+	struct dw_i3c_data *data = dev->data;
+	struct dw_i3c_i2c_dev_data *dw_i2c_device_data = desc->controller_priv;
+
+	__ASSERT_NO_MSG(dw_i2c_device_data != NULL);
+
+	sys_write32(0,
+		    config->regs + DEV_ADDR_TABLE_LOC(data->datstartaddr, dw_i2c_device_data->id));
+	data->free_pos |= BIT(dw_i2c_device_data->id);
+	desc->controller_priv = NULL;
+}
+
 /**
  * @brief Transfer messages in I2C mode.
  *
@@ -921,12 +929,6 @@ static int dw_i3c_i2c_transfer(const struct device *dev, struct i3c_i2c_device_d
 		return -ENOTSUP;
 	}
 
-	pos = get_i2c_addr_pos(dev, target->addr);
-	if (pos < 0) {
-		LOG_ERR("%s: Invalid slave device", dev->name);
-		return -EINVAL;
-	}
-
 	for (i = 0; i < num_msgs; i++) {
 		if (msgs[i].flags & I2C_MSG_READ) {
 			nrxwords += DIV_ROUND_UP(msgs[i].len, 4);
@@ -947,6 +949,17 @@ static int dw_i3c_i2c_transfer(const struct device *dev, struct i3c_i2c_device_d
 
 	pm_device_busy_set(dev);
 
+	/* In order limit the number of retaining registers occupied by connected devices,
+	 * I2C devices are only configured during transfers. This allows the number of devices
+	 * to be larger than the number of retaining registers on mixed buses.
+	 */
+	ret = dw_i3c_i2c_attach_device(dev, target);
+	if (ret != 0) {
+		LOG_ERR("%s: Failed to attach I2C device (%d)", dev->name, ret);
+		goto error_attach;
+	}
+	pos = ((struct dw_i3c_i2c_dev_data *)target->controller_priv)->id;
+
 	memset(xfer, 0, sizeof(struct dw_i3c_xfer));
 
 	xfer->ncmds = num_msgs;
@@ -1002,6 +1015,8 @@ static int dw_i3c_i2c_transfer(const struct device *dev, struct i3c_i2c_device_d
 	ret = xfer->ret;
 
 error:
+	dw_i3c_i2c_detach_device(dev, target);
+error_attach:
 	pm_device_busy_clear(dev);
 	k_mutex_unlock(&data->mt);
 
@@ -1032,25 +1047,22 @@ static struct i3c_i2c_device_desc *dw_i3c_i2c_device_find(const struct device *d
  * @see i2c_transfer
  *
  * @param dev Pointer to device driver instance.
- * @param target Pointer to target device descriptor.
  * @param msgs Pointer to I2C messages.
  * @param num_msgs Number of messages to transfers.
+ * @param addr Address of the I2C target device.
  *
  * @return @see i2c_transfer
  */
 static int dw_i3c_i2c_api_transfer(const struct device *dev, struct i2c_msg *msgs, uint8_t num_msgs,
 				   uint16_t addr)
 {
 	struct i3c_i2c_device_desc *i2c_dev = dw_i3c_i2c_device_find(dev, addr);
-	int ret;
 
 	if (i2c_dev == NULL) {
-		ret = -ENODEV;
-	} else {
-		ret = dw_i3c_i2c_transfer(dev, i2c_dev, msgs, num_msgs);
+		return -ENODEV;
 	}
 
-	return ret;
+	return dw_i3c_i2c_transfer(dev, i2c_dev, msgs, num_msgs);
 }
 
 #ifdef CONFIG_I3C_USE_IBI
@@ -1571,50 +1583,6 @@ static int dw_i3c_detach_device(const struct device *dev, struct i3c_device_desc
 	return 0;
 }
 
-static int dw_i3c_i2c_attach_device(const struct device *dev, struct i3c_i2c_device_desc *desc)
-{
-	const struct dw_i3c_config *config = dev->config;
-	struct dw_i3c_data *data = dev->data;
-	uint8_t pos;
-
-	pos = get_free_pos(data->free_pos);
-	if (pos < 0) {
-		return -ENOSPC;
-	}
-
-	data->dw_i3c_i2c_priv_data[pos].id = pos;
-	desc->controller_priv = &(data->dw_i3c_i2c_priv_data[pos]);
-	data->free_pos &= ~BIT(pos);
-
-	sys_write32(DEV_ADDR_TABLE_LEGACY_I2C_DEV | DEV_ADDR_TABLE_STATIC_ADDR(desc->addr),
-		    config->regs + DEV_ADDR_TABLE_LOC(data->datstartaddr, pos));
-
-	return 0;
-}
-
-static int dw_i3c_i2c_detach_device(const struct device *dev, struct i3c_i2c_device_desc *desc)
-{
-	const struct dw_i3c_config *config = dev->config;
-	struct dw_i3c_data *data = dev->data;
-	struct dw_i3c_i2c_dev_data *dw_i2c_device_data = desc->controller_priv;
-
-	if (dw_i2c_device_data == NULL) {
-		LOG_ERR("%s: device not attached", dev->name);
-		return -EINVAL;
-	}
-
-	k_mutex_lock(&data->mt, K_FOREVER);
-
-	sys_write32(0,
-		    config->regs + DEV_ADDR_TABLE_LOC(data->datstartaddr, dw_i2c_device_data->id));
-	data->free_pos |= BIT(dw_i2c_device_data->id);
-	desc->controller_priv = NULL;
-
-	k_mutex_unlock(&data->mt);
-
-	return 0;
-}
-
 static int set_controller_info(const struct device *dev)
 {
 	const struct dw_i3c_config *config = dev->config;
@@ -2389,8 +2357,6 @@ static DEVICE_API(i3c, dw_i3c_api) = {
 	.attach_i3c_device = dw_i3c_attach_device,
 	.reattach_i3c_device = dw_i3c_reattach_device,
 	.detach_i3c_device = dw_i3c_detach_device,
-	.attach_i2c_device = dw_i3c_i2c_attach_device,
-	.detach_i2c_device = dw_i3c_i2c_detach_device,
 
 	.do_daa = dw_i3c_do_daa,
 	.do_ccc = dw_i3c_do_ccc,