From: Luca Ceresoli <luca@xxxxxxxxxxxxxxxx> An ATR is a device that looks similar to an i2c-mux: it has an I2C slave "upstream" port and N master "downstream" ports, and forwards transactions from upstream to the appropriate downstream port. But it is different in that the forwarded transaction has a different slave address. The address used on the upstream bus is called the "alias" and is (potentially) different from the physical slave address of the downstream chip. Add a helper file (just like i2c-mux.c for a mux or switch) to allow implementing ATR features in a device driver. The helper takes care or adapter creation/destruction and translates addresses at each transaction. Signed-off-by: Luca Ceresoli <luca@xxxxxxxxxxxxxxxx> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx> Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> --- .../devicetree/bindings/i2c/i2c-atr.yaml | 34 + Documentation/i2c/i2c-address-translators.rst | 96 +++ Documentation/i2c/index.rst | 1 + MAINTAINERS | 8 + drivers/i2c/Kconfig | 9 + drivers/i2c/Makefile | 1 + drivers/i2c/i2c-atr.c | 684 ++++++++++++++++++ include/linux/i2c-atr.h | 116 +++ 8 files changed, 949 insertions(+) create mode 100644 Documentation/devicetree/bindings/i2c/i2c-atr.yaml create mode 100644 Documentation/i2c/i2c-address-translators.rst create mode 100644 drivers/i2c/i2c-atr.c create mode 100644 include/linux/i2c-atr.h diff --git a/Documentation/devicetree/bindings/i2c/i2c-atr.yaml b/Documentation/devicetree/bindings/i2c/i2c-atr.yaml new file mode 100644 index 000000000000..d7f73d98110d --- /dev/null +++ b/Documentation/devicetree/bindings/i2c/i2c-atr.yaml @@ -0,0 +1,34 @@ +# SPDX-License-Identifier: GPL-2.0 +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/i2c/i2c-atr.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Common i2c address translator properties. + +maintainers: + - Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx> + +description: + An I2C Address Translator (ATR) is a device with an I2C slave parent + ("upstream") port and N I2C master child ("downstream") ports, and + forwards transactions from upstream to the appropriate downstream port + with a modified slave address. The address used on the parent bus is + called the "alias" and is (potentially) different from the physical + slave address of the child bus. Address translation is done by the + hardware. + +properties: + i2c-alias-pool: + $ref: /schemas/types.yaml#/definitions/uint16-array + description: + I2C alias pool is a pool of I2C addresses on the main I2C bus that can be + used to access the remote peripherals on the serializer's I2C bus. The + addresses must be available, not used by any other peripheral. Each + remote peripheral is assigned an alias from the pool, and transactions to + that address will be forwarded to the remote peripheral, with the address + translated to the remote peripheral's real address. This property is not + needed if there are no I2C addressable remote peripherals. + +additionalProperties: true +... diff --git a/Documentation/i2c/i2c-address-translators.rst b/Documentation/i2c/i2c-address-translators.rst new file mode 100644 index 000000000000..b22ce9f41ecf --- /dev/null +++ b/Documentation/i2c/i2c-address-translators.rst @@ -0,0 +1,96 @@ +.. SPDX-License-Identifier: GPL-2.0 + +======================= +I2C Address Translators +======================= + +Author: Luca Ceresoli <luca@xxxxxxxxxxxxxxxx> +Author: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx> + +Description +----------- + +An I2C Address Translator (ATR) is a device with an I2C slave parent +("upstream") port and N I2C master child ("downstream") ports, and +forwards transactions from upstream to the appropriate downstream port +with a modified slave address. The address used on the parent bus is +called the "alias" and is (potentially) different from the physical +slave address of the child bus. Address translation is done by the +hardware. + +An ATR looks similar to an i2c-mux except: + - the address on the parent and child busses can be different + - there is normally no need to select the child port; the alias used on the + parent bus implies it + +The ATR functionality can be provided by a chip with many other features. +The kernel i2c-atr provides a helper to implement an ATR within a driver. + +The ATR creates a new I2C "child" adapter on each child bus. Adding +devices on the child bus ends up in invoking the driver code to select +an available alias. Maintaining an appropriate pool of available aliases +and picking one for each new device is up to the driver implementer. The +ATR maintains a table of currently assigned alias and uses it to modify +all I2C transactions directed to devices on the child buses. + +A typical example follows. + +Topology:: + + Slave X @ 0x10 + .-----. | + .-----. | |---+---- B + | CPU |--A--| ATR | + `-----' | |---+---- C + `-----' | + Slave Y @ 0x10 + +Alias table: + +A, B and C are three physical I2C busses, electrically independent from +each other. The ATR receives the transactions initiated on bus A and +propagates them on bus B or bus C or none depending on the device address +in the transaction and based on the alias table. + +Alias table: + +.. table:: + + =============== ===== + Client Alias + =============== ===== + X (bus B, 0x10) 0x20 + Y (bus C, 0x10) 0x30 + =============== ===== + +Transaction: + + - Slave X driver requests a transaction (on adapter B), slave address 0x10 + - ATR driver finds slave X is on bus B and has alias 0x20, rewrites + messages with address 0x20, forwards to adapter A + - Physical I2C transaction on bus A, slave address 0x20 + - ATR chip detects transaction on address 0x20, finds it in table, + propagates transaction on bus B with address translated to 0x10, + keeps clock streched on bus A waiting for reply + - Slave X chip (on bus B) detects transaction at its own physical + address 0x10 and replies normally + - ATR chip stops clock stretching and forwards reply on bus A, + with address translated back to 0x20 + - ATR driver receives the reply, rewrites messages with address 0x10 + as they were initially + - Slave X driver gets back the msgs[], with reply and address 0x10 + +Usage: + + 1. In the driver (typically in the probe function) add an ATR by + calling i2c_atr_new() passing attach/detach callbacks + 2. When the attach callback is called pick an appropriate alias, + configure it in the chip and return the chosen alias in the + alias_id parameter + 3. When the detach callback is called, deconfigure the alias from + the chip and put the alias back in the pool for later usage + +I2C ATR functions and data structures +------------------------------------- + +.. kernel-doc:: include/linux/i2c-atr.h diff --git a/Documentation/i2c/index.rst b/Documentation/i2c/index.rst index 6270f1fd7d4e..2b213d4ce89c 100644 --- a/Documentation/i2c/index.rst +++ b/Documentation/i2c/index.rst @@ -18,6 +18,7 @@ Introduction i2c-topology muxes/i2c-mux-gpio i2c-sysfs + i2c-address-translators Writing device drivers ====================== diff --git a/MAINTAINERS b/MAINTAINERS index e25ebb7c781b..348bc924a56f 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -9559,6 +9559,14 @@ L: linux-acpi@xxxxxxxxxxxxxxx S: Maintained F: drivers/i2c/i2c-core-acpi.c +I2C ADDRESS TRANSLATOR (ATR) +M: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx> +R: Luca Ceresoli <luca.ceresoli@xxxxxxxxxxx> +L: linux-i2c@xxxxxxxxxxxxxxx +S: Maintained +F: drivers/i2c/i2c-atr.c +F: include/linux/i2c-atr.h + I2C CONTROLLER DRIVER FOR NVIDIA GPU M: Ajay Gupta <ajayg@xxxxxxxxxx> L: linux-i2c@xxxxxxxxxxxxxxx diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig index 438905e2a1d0..c6d1a345ea6d 100644 --- a/drivers/i2c/Kconfig +++ b/drivers/i2c/Kconfig @@ -71,6 +71,15 @@ config I2C_MUX source "drivers/i2c/muxes/Kconfig" +config I2C_ATR + tristate "I2C Address Translator (ATR) support" + help + Enable support for I2C Address Translator (ATR) chips. + + An ATR allows accessing multiple I2C busses from a single + physical bus via address translation instead of bus selection as + i2c-muxes do. + config I2C_HELPER_AUTO bool "Autoselect pertinent helper modules" default y diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile index c1d493dc9bac..3f71ce4711e3 100644 --- a/drivers/i2c/Makefile +++ b/drivers/i2c/Makefile @@ -13,6 +13,7 @@ i2c-core-$(CONFIG_OF) += i2c-core-of.o obj-$(CONFIG_I2C_SMBUS) += i2c-smbus.o obj-$(CONFIG_I2C_CHARDEV) += i2c-dev.o obj-$(CONFIG_I2C_MUX) += i2c-mux.o +obj-$(CONFIG_I2C_ATR) += i2c-atr.o obj-y += algos/ busses/ muxes/ obj-$(CONFIG_I2C_STUB) += i2c-stub.o obj-$(CONFIG_I2C_SLAVE_EEPROM) += i2c-slave-eeprom.o diff --git a/drivers/i2c/i2c-atr.c b/drivers/i2c/i2c-atr.c new file mode 100644 index 000000000000..402182a04efd --- /dev/null +++ b/drivers/i2c/i2c-atr.c @@ -0,0 +1,684 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * I2C Address Translator + * + * Copyright (c) 2019,2022 Luca Ceresoli <luca@xxxxxxxxxxxxxxxx> + * Copyright (c) 2022,2023 Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx> + * + * Originally based on i2c-mux.c + */ + +#include <linux/fwnode.h> +#include <linux/i2c-atr.h> +#include <linux/i2c.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/slab.h> +#include <linux/spinlock.h> + +#define ATR_MAX_ADAPTERS 100 /* Just a sanity limit */ +#define ATR_MAX_SYMLINK_LEN 11 /* Longest name is 10 chars: "channel-99" */ + +/** + * struct i2c_atr_alias_pair - Holds the alias assigned to a client. + * @node: List node + * @client: Pointer to the client on the child bus + * @alias: I2C alias address assigned by the driver. + * This is the address that will be used to issue I2C transactions + * on the parent (physical) bus. + */ +struct i2c_atr_alias_pair { + struct list_head node; + const struct i2c_client *client; + u16 alias; +}; + +/** + * struct i2c_atr_chan - Data for a channel. + * @adap: The &struct i2c_adapter for the channel + * @atr: The parent I2C ATR + * @chan_id: The ID of this channel + * @alias_list: List of @struct i2c_atr_alias_pair containing the + * assigned aliases + * @orig_addrs_lock: Mutex protecting @orig_addrs + * @orig_addrs: Buffer used to store the original addresses during transmit + * @orig_addrs_size: Size of @orig_addrs + */ +struct i2c_atr_chan { + struct i2c_adapter adap; + struct i2c_atr *atr; + u32 chan_id; + + struct list_head alias_list; + + /* Lock orig_addrs during xfer */ + struct mutex orig_addrs_lock; + u16 *orig_addrs; + unsigned int orig_addrs_size; +}; + +/** + * struct i2c_atr - The I2C ATR instance + * @parent: The parent &struct i2c_adapter + * @dev: The device that owns the I2C ATR instance + * @ops: &struct i2c_atr_ops + * @priv: Private driver data, set with i2c_atr_set_driver_data() + * @algo: The &struct i2c_algorithm for adapters + * @lock: Lock for the I2C bus segment (see &struct i2c_lock_operations) + * @max_adapters: Maximum number of adapters this I2C ATR can have + * @num_aliases: Number of aliases in the aliases array + * @aliases: The aliases array + * @alias_mask_lock: Lock protecting alias_use_mask + * @alias_use_mask: Bitmask for used aliases in aliases array + * @i2c_nb: Notifier for remote client add & del events + * @adapter: Array of adapters + */ +struct i2c_atr { + struct i2c_adapter *parent; + struct device *dev; + const struct i2c_atr_ops *ops; + + void *priv; + + struct i2c_algorithm algo; + /* lock for the I2C bus segment (see struct i2c_lock_operations) */ + struct mutex lock; + int max_adapters; + + size_t num_aliases; + const u16 *aliases; + /* Protects alias_use_mask */ + spinlock_t alias_mask_lock; + unsigned long *alias_use_mask; + + struct notifier_block i2c_nb; + + struct i2c_adapter *adapter[]; +}; + +static struct i2c_atr_alias_pair * +i2c_atr_find_mapping_by_client(const struct list_head *list, + const struct i2c_client *client) +{ + struct i2c_atr_alias_pair *c2a; + + list_for_each_entry(c2a, list, node) { + if (c2a->client == client) + return c2a; + } + + return NULL; +} + +static struct i2c_atr_alias_pair * +i2c_atr_find_mapping_by_addr(const struct list_head *list, u16 phys_addr) +{ + struct i2c_atr_alias_pair *c2a; + + list_for_each_entry(c2a, list, node) { + if (c2a->client->addr == phys_addr) + return c2a; + } + + return NULL; +} + +/* + * Replace all message addresses with their aliases, saving the original + * addresses. + * + * This function is internal for use in i2c_atr_master_xfer(). It must be + * followed by i2c_atr_unmap_msgs() to restore the original addresses. + */ +static int i2c_atr_map_msgs(struct i2c_atr_chan *chan, struct i2c_msg *msgs, + int num) +{ + struct i2c_atr *atr = chan->atr; + static struct i2c_atr_alias_pair *c2a; + int i; + + /* Ensure we have enough room to save the original addresses */ + if (unlikely(chan->orig_addrs_size < num)) { + u16 *new_buf; + + /* We don't care about old data, hence no realloc() */ + new_buf = kmalloc_array(num, sizeof(*new_buf), GFP_KERNEL); + if (!new_buf) + return -ENOMEM; + + kfree(chan->orig_addrs); + chan->orig_addrs = new_buf; + chan->orig_addrs_size = num; + } + + for (i = 0; i < num; i++) { + chan->orig_addrs[i] = msgs[i].addr; + + c2a = i2c_atr_find_mapping_by_addr(&chan->alias_list, + msgs[i].addr); + if (!c2a) { + dev_err(atr->dev, "client 0x%02x not mapped!\n", + msgs[i].addr); + + while (i--) + msgs[i].addr = chan->orig_addrs[i]; + + return -ENXIO; + } + + msgs[i].addr = c2a->alias; + } + + return 0; +} + +/* + * Restore all message address aliases with the original addresses. This + * function is internal for use in i2c_atr_master_xfer() and for this reason it + * needs no null and size checks on orig_addr. + * + * @see i2c_atr_map_msgs() + */ +static void i2c_atr_unmap_msgs(struct i2c_atr_chan *chan, struct i2c_msg *msgs, + int num) +{ + int i; + + for (i = 0; i < num; i++) + msgs[i].addr = chan->orig_addrs[i]; +} + +static int i2c_atr_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, + int num) +{ + struct i2c_atr_chan *chan = adap->algo_data; + struct i2c_atr *atr = chan->atr; + struct i2c_adapter *parent = atr->parent; + int ret; + + /* Translate addresses */ + mutex_lock(&chan->orig_addrs_lock); + + ret = i2c_atr_map_msgs(chan, msgs, num); + if (ret < 0) + goto err_unlock; + + /* Perform the transfer */ + ret = i2c_transfer(parent, msgs, num); + + /* Restore addresses */ + i2c_atr_unmap_msgs(chan, msgs, num); + +err_unlock: + mutex_unlock(&chan->orig_addrs_lock); + + return ret; +} + +static int i2c_atr_smbus_xfer(struct i2c_adapter *adap, u16 addr, + unsigned short flags, char read_write, u8 command, + int size, union i2c_smbus_data *data) +{ + struct i2c_atr_chan *chan = adap->algo_data; + struct i2c_atr *atr = chan->atr; + struct i2c_adapter *parent = atr->parent; + struct i2c_atr_alias_pair *c2a; + + c2a = i2c_atr_find_mapping_by_addr(&chan->alias_list, addr); + if (!c2a) { + dev_err(atr->dev, "client 0x%02x not mapped!\n", addr); + return -ENXIO; + } + + return i2c_smbus_xfer(parent, c2a->alias, flags, read_write, command, + size, data); +} + +static u32 i2c_atr_functionality(struct i2c_adapter *adap) +{ + struct i2c_atr_chan *chan = adap->algo_data; + struct i2c_adapter *parent = chan->atr->parent; + + return parent->algo->functionality(parent); +} + +static void i2c_atr_lock_bus(struct i2c_adapter *adapter, unsigned int flags) +{ + struct i2c_atr_chan *chan = adapter->algo_data; + struct i2c_atr *atr = chan->atr; + + mutex_lock(&atr->lock); +} + +static int i2c_atr_trylock_bus(struct i2c_adapter *adapter, unsigned int flags) +{ + struct i2c_atr_chan *chan = adapter->algo_data; + struct i2c_atr *atr = chan->atr; + + return mutex_trylock(&atr->lock); +} + +static void i2c_atr_unlock_bus(struct i2c_adapter *adapter, unsigned int flags) +{ + struct i2c_atr_chan *chan = adapter->algo_data; + struct i2c_atr *atr = chan->atr; + + mutex_unlock(&atr->lock); +} + +static const struct i2c_lock_operations i2c_atr_lock_ops = { + .lock_bus = i2c_atr_lock_bus, + .trylock_bus = i2c_atr_trylock_bus, + .unlock_bus = i2c_atr_unlock_bus, +}; + +static int i2c_atr_reserve_alias(struct i2c_atr *atr) +{ + unsigned long idx; + + spin_lock(&atr->alias_mask_lock); + + idx = find_first_zero_bit(atr->alias_use_mask, atr->num_aliases); + if (idx >= atr->num_aliases) { + spin_unlock(&atr->alias_mask_lock); + dev_err(atr->dev, "failed to find a free alias\n"); + return -EBUSY; + } + + set_bit(idx, atr->alias_use_mask); + + spin_unlock(&atr->alias_mask_lock); + + return atr->aliases[idx]; +} + +static void i2c_atr_release_alias(struct i2c_atr *atr, u16 alias) +{ + unsigned int idx; + + spin_lock(&atr->alias_mask_lock); + + for (idx = 0; idx < atr->num_aliases; ++idx) { + if (atr->aliases[idx] == alias) { + clear_bit(idx, atr->alias_use_mask); + spin_unlock(&atr->alias_mask_lock); + return; + } + } + + spin_unlock(&atr->alias_mask_lock); + + /* This should never happen */ + dev_warn(atr->dev, "Unable to find mapped alias\n"); +} + +static int i2c_atr_attach_client(struct i2c_adapter *adapter, + const struct i2c_client *client) +{ + struct i2c_atr_chan *chan = adapter->algo_data; + struct i2c_atr *atr = chan->atr; + struct i2c_atr_alias_pair *c2a; + u16 alias; + int ret; + + ret = i2c_atr_reserve_alias(atr); + if (ret < 0) + return ret; + + alias = ret; + + c2a = kzalloc(sizeof(*c2a), GFP_KERNEL); + if (!c2a) { + ret = -ENOMEM; + goto err_release_alias; + } + + ret = atr->ops->attach_client(atr, chan->chan_id, client, alias); + if (ret) + goto err_free; + + dev_dbg(atr->dev, "chan%u: client 0x%02x mapped at alias 0x%02x (%s)\n", + chan->chan_id, client->addr, alias, client->name); + + c2a->client = client; + c2a->alias = alias; + list_add(&c2a->node, &chan->alias_list); + + return 0; + +err_free: + kfree(c2a); +err_release_alias: + i2c_atr_release_alias(atr, alias); + + return ret; +} + +static void i2c_atr_detach_client(struct i2c_adapter *adapter, + const struct i2c_client *client) +{ + struct i2c_atr_chan *chan = adapter->algo_data; + struct i2c_atr *atr = chan->atr; + struct i2c_atr_alias_pair *c2a; + + atr->ops->detach_client(atr, chan->chan_id, client); + + c2a = i2c_atr_find_mapping_by_client(&chan->alias_list, client); + if (!c2a) { + /* This should never happen */ + dev_warn(atr->dev, "Unable to find address mapping\n"); + return; + } + + i2c_atr_release_alias(atr, c2a->alias); + + dev_dbg(atr->dev, + "chan%u: client 0x%02x unmapped from alias 0x%02x (%s)\n", + chan->chan_id, client->addr, c2a->alias, client->name); + + list_del(&c2a->node); + kfree(c2a); +} + +static int i2c_atr_bus_notifier_call(struct notifier_block *nb, + unsigned long event, void *device) +{ + struct i2c_atr *atr = container_of(nb, struct i2c_atr, i2c_nb); + struct device *dev = device; + struct i2c_client *client; + u32 chan_id; + int ret; + + client = i2c_verify_client(dev); + if (!client) + return NOTIFY_DONE; + + /* Is the client in one of our adapters? */ + for (chan_id = 0; chan_id < atr->max_adapters; ++chan_id) { + if (client->adapter == atr->adapter[chan_id]) + break; + } + + if (chan_id == atr->max_adapters) + return NOTIFY_DONE; + + switch (event) { + case BUS_NOTIFY_ADD_DEVICE: + ret = i2c_atr_attach_client(client->adapter, client); + if (ret) + dev_err(atr->dev, + "Failed to attach remote client '%s': %d\n", + dev_name(dev), ret); + break; + + case BUS_NOTIFY_DEL_DEVICE: + i2c_atr_detach_client(client->adapter, client); + break; + + default: + break; + } + + return NOTIFY_DONE; +} + +static int i2c_atr_parse_alias_pool(struct i2c_atr *atr) +{ + struct device *dev = atr->dev; + unsigned long *alias_use_mask; + size_t num_aliases; + u16 *aliases; + int ret; + + ret = fwnode_property_count_u16(dev_fwnode(dev), "i2c-alias-pool"); + if (ret < 0) { + dev_err(dev, "Failed to count 'i2c-alias-pool' property: %d\n", + ret); + return ret; + } + + num_aliases = ret; + + if (!num_aliases) + return 0; + + aliases = kcalloc(num_aliases, sizeof(*aliases), GFP_KERNEL); + if (!aliases) + return -ENOMEM; + + ret = fwnode_property_read_u16_array(dev_fwnode(dev), "i2c-alias-pool", + aliases, num_aliases); + if (ret < 0) { + dev_err(dev, "Failed to read 'i2c-alias-pool' property: %d\n", + ret); + kfree(aliases); + return ret; + } + + alias_use_mask = bitmap_zalloc(num_aliases, GFP_KERNEL); + if (!alias_use_mask) { + kfree(aliases); + return -ENOMEM; + } + + atr->num_aliases = num_aliases; + atr->aliases = aliases; + atr->alias_use_mask = alias_use_mask; + + dev_dbg(dev, "i2c-alias-pool has %zu aliases", atr->num_aliases); + + return 0; +} + +struct i2c_atr *i2c_atr_new(struct i2c_adapter *parent, struct device *dev, + const struct i2c_atr_ops *ops, int max_adapters) +{ + struct i2c_atr *atr; + int ret; + + if (max_adapters > ATR_MAX_ADAPTERS) + return ERR_PTR(-EINVAL); + + if (!ops || !ops->attach_client || !ops->detach_client) + return ERR_PTR(-EINVAL); + + atr = kzalloc(struct_size(atr, adapter, max_adapters), GFP_KERNEL); + if (!atr) + return ERR_PTR(-ENOMEM); + + mutex_init(&atr->lock); + spin_lock_init(&atr->alias_mask_lock); + + atr->parent = parent; + atr->dev = dev; + atr->ops = ops; + atr->max_adapters = max_adapters; + + if (parent->algo->master_xfer) + atr->algo.master_xfer = i2c_atr_master_xfer; + if (parent->algo->smbus_xfer) + atr->algo.smbus_xfer = i2c_atr_smbus_xfer; + atr->algo.functionality = i2c_atr_functionality; + + ret = i2c_atr_parse_alias_pool(atr); + if (ret) + goto err_destroy_mutex; + + atr->i2c_nb.notifier_call = i2c_atr_bus_notifier_call; + ret = bus_register_notifier(&i2c_bus_type, &atr->i2c_nb); + if (ret) + goto err_free_aliases; + + return atr; + +err_free_aliases: + bitmap_free(atr->alias_use_mask); + kfree(atr->aliases); +err_destroy_mutex: + mutex_destroy(&atr->lock); + kfree(atr); + + return ERR_PTR(ret); +} +EXPORT_SYMBOL_NS_GPL(i2c_atr_new, I2C_ATR); + +void i2c_atr_delete(struct i2c_atr *atr) +{ + unsigned int i; + + for (i = 0; i < atr->max_adapters; ++i) + WARN_ON(atr->adapter[i]); + + bus_unregister_notifier(&i2c_bus_type, &atr->i2c_nb); + bitmap_free(atr->alias_use_mask); + kfree(atr->aliases); + mutex_destroy(&atr->lock); + kfree(atr); +} +EXPORT_SYMBOL_NS_GPL(i2c_atr_delete, I2C_ATR); + +int i2c_atr_add_adapter(struct i2c_atr *atr, u32 chan_id, + struct device *adapter_parent, + struct fwnode_handle *bus_handle) +{ + struct i2c_adapter *parent = atr->parent; + struct device *dev = atr->dev; + struct i2c_atr_chan *chan; + char symlink_name[ATR_MAX_SYMLINK_LEN]; + int ret; + + if (chan_id >= atr->max_adapters) { + dev_err(dev, "No room for more i2c-atr adapters\n"); + return -EINVAL; + } + + if (atr->adapter[chan_id]) { + dev_err(dev, "Adapter %d already present\n", chan_id); + return -EEXIST; + } + + chan = kzalloc(sizeof(*chan), GFP_KERNEL); + if (!chan) + return -ENOMEM; + + if (!adapter_parent) + adapter_parent = dev; + + chan->atr = atr; + chan->chan_id = chan_id; + INIT_LIST_HEAD(&chan->alias_list); + mutex_init(&chan->orig_addrs_lock); + + snprintf(chan->adap.name, sizeof(chan->adap.name), "i2c-%d-atr-%d", + i2c_adapter_id(parent), chan_id); + chan->adap.owner = THIS_MODULE; + chan->adap.algo = &atr->algo; + chan->adap.algo_data = chan; + chan->adap.dev.parent = adapter_parent; + chan->adap.retries = parent->retries; + chan->adap.timeout = parent->timeout; + chan->adap.quirks = parent->quirks; + chan->adap.lock_ops = &i2c_atr_lock_ops; + + if (bus_handle) { + device_set_node(&chan->adap.dev, fwnode_handle_get(bus_handle)); + } else { + struct fwnode_handle *atr_node; + struct fwnode_handle *child; + u32 reg; + + atr_node = device_get_named_child_node(dev, "i2c-atr"); + + fwnode_for_each_child_node(atr_node, child) { + ret = fwnode_property_read_u32(child, "reg", ®); + if (ret) + continue; + if (chan_id == reg) + break; + } + + device_set_node(&chan->adap.dev, child); + fwnode_handle_put(atr_node); + } + + atr->adapter[chan_id] = &chan->adap; + + ret = i2c_add_adapter(&chan->adap); + if (ret) { + dev_err(dev, "failed to add atr-adapter %u (error=%d)\n", + chan_id, ret); + goto err_fwnode_put; + } + + snprintf(symlink_name, sizeof(symlink_name), "channel-%u", + chan->chan_id); + + ret = sysfs_create_link(&chan->adap.dev.kobj, &dev->kobj, "atr_device"); + if (ret) + dev_warn(dev, "can't create symlink to atr device\n"); + ret = sysfs_create_link(&dev->kobj, &chan->adap.dev.kobj, symlink_name); + if (ret) + dev_warn(dev, "can't create symlink for channel %u\n", chan_id); + + dev_dbg(dev, "Added ATR child bus %d\n", i2c_adapter_id(&chan->adap)); + + return 0; + +err_fwnode_put: + fwnode_handle_put(dev_fwnode(&chan->adap.dev)); + mutex_destroy(&chan->orig_addrs_lock); + kfree(chan); + return ret; +} +EXPORT_SYMBOL_NS_GPL(i2c_atr_add_adapter, I2C_ATR); + +void i2c_atr_del_adapter(struct i2c_atr *atr, u32 chan_id) +{ + char symlink_name[ATR_MAX_SYMLINK_LEN]; + struct i2c_adapter *adap; + struct i2c_atr_chan *chan; + struct fwnode_handle *fwnode; + struct device *dev = atr->dev; + + adap = atr->adapter[chan_id]; + if (!adap) + return; + + chan = adap->algo_data; + fwnode = dev_fwnode(&adap->dev); + + dev_dbg(dev, "Removing ATR child bus %d\n", i2c_adapter_id(adap)); + + snprintf(symlink_name, sizeof(symlink_name), "channel-%u", + chan->chan_id); + sysfs_remove_link(&dev->kobj, symlink_name); + sysfs_remove_link(&chan->adap.dev.kobj, "atr_device"); + + i2c_del_adapter(adap); + + atr->adapter[chan_id] = NULL; + + fwnode_handle_put(fwnode); + mutex_destroy(&chan->orig_addrs_lock); + kfree(chan->orig_addrs); + kfree(chan); +} +EXPORT_SYMBOL_NS_GPL(i2c_atr_del_adapter, I2C_ATR); + +void i2c_atr_set_driver_data(struct i2c_atr *atr, void *data) +{ + atr->priv = data; +} +EXPORT_SYMBOL_NS_GPL(i2c_atr_set_driver_data, I2C_ATR); + +void *i2c_atr_get_driver_data(struct i2c_atr *atr) +{ + return atr->priv; +} +EXPORT_SYMBOL_NS_GPL(i2c_atr_get_driver_data, I2C_ATR); + +MODULE_AUTHOR("Luca Ceresoli <luca.ceresoli@xxxxxxxxxxx>"); +MODULE_AUTHOR("Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>"); +MODULE_DESCRIPTION("I2C Address Translator"); +MODULE_LICENSE("GPL"); diff --git a/include/linux/i2c-atr.h b/include/linux/i2c-atr.h new file mode 100644 index 000000000000..4d5da161c225 --- /dev/null +++ b/include/linux/i2c-atr.h @@ -0,0 +1,116 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * I2C Address Translator + * + * Copyright (c) 2019,2022 Luca Ceresoli <luca@xxxxxxxxxxxxxxxx> + * Copyright (c) 2022,2023 Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx> + * + * Based on i2c-mux.h + */ + +#ifndef _LINUX_I2C_ATR_H +#define _LINUX_I2C_ATR_H + +#include <linux/i2c.h> +#include <linux/types.h> + +struct device; +struct fwnode_handle; +struct i2c_atr; + +/** + * struct i2c_atr_ops - Callbacks from ATR to the device driver. + * @attach_client: Notify the driver of a new device connected on a child + * bus, with the alias assigned to it. The driver must + * configure the hardware to use the alias. + * @detach_client: Notify the driver of a device getting disconnected. The + * driver must configure the hardware to stop using the + * alias. + * + * All these functions return 0 on success, a negative error code otherwise. + */ +struct i2c_atr_ops { + int (*attach_client)(struct i2c_atr *atr, u32 chan_id, + const struct i2c_client *client, u16 alias); + void (*detach_client)(struct i2c_atr *atr, u32 chan_id, + const struct i2c_client *client); +}; + +/** + * i2c_atr_new() - Allocate and initialize an I2C ATR helper. + * @parent: The parent (upstream) adapter + * @dev: The device acting as an ATR + * @ops: Driver-specific callbacks + * @max_adapters: Maximum number of child adapters + * + * The new ATR helper is connected to the parent adapter but has no child + * adapters. Call i2c_atr_add_adapter() to add some. + * + * Call i2c_atr_delete() to remove. + * + * Return: pointer to the new ATR helper object, or ERR_PTR + */ +struct i2c_atr *i2c_atr_new(struct i2c_adapter *parent, struct device *dev, + const struct i2c_atr_ops *ops, int max_adapters); + +/** + * i2c_atr_delete - Delete an I2C ATR helper. + * @atr: I2C ATR helper to be deleted. + * + * Precondition: all the adapters added with i2c_atr_add_adapter() must be + * removed by calling i2c_atr_del_adapter(). + */ +void i2c_atr_delete(struct i2c_atr *atr); + +/** + * i2c_atr_add_adapter - Create a child ("downstream") I2C bus. + * @atr: The I2C ATR + * @chan_id: Index of the new adapter (0 .. max_adapters-1). This value is + * passed to the callbacks in `struct i2c_atr_ops`. + * @adapter_parent: The device used as the parent of the new i2c adapter, or NULL + * to use the i2c-atr device as the parent. + * @bus_handle: The fwnode handle that points to the adapter's i2c + * peripherals, or NULL. + * + * After calling this function a new i2c bus will appear. Adding and removing + * devices on the downstream bus will result in calls to the + * &i2c_atr_ops->attach_client and &i2c_atr_ops->detach_client callbacks for the + * driver to assign an alias to the device. + * + * The adapter's fwnode is set to @bus_handle, or if @bus_handle is NULL the + * function looks for a child node whose 'reg' property matches the chan_id + * under the i2c-atr device's 'i2c-atr' node. + * + * Call i2c_atr_del_adapter() to remove the adapter. + * + * Return: 0 on success, a negative error code otherwise. + */ +int i2c_atr_add_adapter(struct i2c_atr *atr, u32 chan_id, + struct device *adapter_parent, + struct fwnode_handle *bus_handle); + +/** + * i2c_atr_del_adapter - Remove a child ("downstream") I2C bus added by + * i2c_atr_add_adapter(). If no I2C bus has been added + * this function is a no-op. + * @atr: The I2C ATR + * @chan_id: Index of the adapter to be removed (0 .. max_adapters-1) + */ +void i2c_atr_del_adapter(struct i2c_atr *atr, u32 chan_id); + +/** + * i2c_atr_set_driver_data - Set private driver data to the i2c-atr instance. + * @atr: The I2C ATR + * @data: Pointer to the data to store + */ +void i2c_atr_set_driver_data(struct i2c_atr *atr, void *data); + +/** + * i2c_atr_get_driver_data - Get the stored drive data. + * @atr: The I2C ATR + * + * Return: Pointer to the stored data + */ +void *i2c_atr_get_driver_data(struct i2c_atr *atr); + +#endif /* _LINUX_I2C_ATR_H */ -- 2.34.1
