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[209.132.180.67]) by mx.google.com with ESMTP id r67si11992371pjb.19.2019.07.23.19.30.16; Tue, 23 Jul 2019 19:30:32 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389063AbfGWUhr (ORCPT + 99 others); Tue, 23 Jul 2019 16:37:47 -0400 Received: from hostingweb31-40.netsons.net ([89.40.174.40]:42906 "EHLO hostingweb31-40.netsons.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388990AbfGWUhp (ORCPT ); Tue, 23 Jul 2019 16:37:45 -0400 Received: from [88.149.224.16] (port=34022 helo=melee.fritz.box) by hostingweb31.netsons.net with esmtpa (Exim 4.92) (envelope-from ) id 1hq1XY-007idA-V4; Tue, 23 Jul 2019 22:37:41 +0200 From: Luca Ceresoli To: linux-media@vger.kernel.org, linux-i2c@vger.kernel.org Cc: Luca Ceresoli , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Mauro Carvalho Chehab , Rob Herring , Mark Rutland , Wolfram Sang , Sakari Ailus , Hans Verkuil , Laurent Pinchart , Kieran Bingham , Jacopo Mondi , Vladimir Zapolskiy , Peter Rosin Subject: [RFC,v2 2/6] i2c: add I2C Address Translator (ATR) support Date: Tue, 23 Jul 2019 22:37:19 +0200 Message-Id: <20190723203723.11730-3-luca@lucaceresoli.net> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190723203723.11730-1-luca@lucaceresoli.net> References: <20190723203723.11730-1-luca@lucaceresoli.net> X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - hostingweb31.netsons.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - lucaceresoli.net X-Get-Message-Sender-Via: hostingweb31.netsons.net: authenticated_id: luca+lucaceresoli.net/only user confirmed/virtual account not confirmed X-Authenticated-Sender: hostingweb31.netsons.net: luca@lucaceresoli.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 is 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 --- Changes RFCv1 -> RFCv2: RFCv1 was implemented inside i2c-mux.c and added yet more complexity there. RFCv2 creates a new file on its own, i2c-atr.c. Since many ATR features are not in a MUX and vice versa, the overlapping is low. This was almost a complete rewrite, but for the records here are the main differences from the old implementation: - change bus description - remove I2C_ATR_ARBITRATOR and I2C_ATR_GATE support - select() optional - rename i2c_atr_alloc -> i2c_atr_new, add i2c_atr_delete, move to bottom - lock the ATR, not the adapter or the muxes on the adapter - remove parent-locked code - remove I2C_MUX_LOCKED flag, now unused - remove I2C_ATR_ATR flag (always true) - translation in i2c_atr_smbus_xfer too - i2c_atr_map_msgs: don't ignore mapping errors - always require the "i2c-atr" DT node, no magic - remove ACPI support - one algo in the atrc, not one per adapter - remove unneeded i2c_atr_root_adapter - ditch force_nr - don't allocate private user memory, just provide a plain userdata pointer - consolidate all ops in a single struct, simplify naming - remove adapters individually, allocate in atrc->adapter[chan_id] --- drivers/i2c/Kconfig | 9 + drivers/i2c/Makefile | 1 + drivers/i2c/i2c-atr.c | 557 ++++++++++++++++++++++++++++++++++++++++ include/linux/i2c-atr.h | 82 ++++++ 4 files changed, 649 insertions(+) create mode 100644 drivers/i2c/i2c-atr.c create mode 100644 include/linux/i2c-atr.h diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig index abedd55a1264..5df088b1d9de 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 bed6ba63c983..81849ea393c7 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..2b61c10a8ff6 --- /dev/null +++ b/drivers/i2c/i2c-atr.c @@ -0,0 +1,557 @@ +// SPDX-License-Identifier: GPL-2.0 +/** + * drivers/i2c/i2c-atr.c -- I2C Address Translator + * + * Copyright (c) 2019 Luca Ceresoli + * + * 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. This file provides a helper to implement an ATR within your + * 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 an 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: + * + * Client Alias + * ------------- + * X 0x20 + * Y 0x30 + * + * Transaction: + * + * - Slave X driver sends a transaction (on adapter B), slave address 0x10 + * - ATR driver rewrites messages with address 0x20, forwards to adapter A + * - Physical I2C transaction on bus A, slave address 0x20 + * - ATR chip propagates transaction on bus B with address translated to 0x10 + * - Slave X chip replies on bus B + * - ATR chip forwards reply on bus A + * - ATR driver rewrites messages with address 0x10 + * - Slave X driver gets back the msgs[], with reply and address 0x10 + * + * Usage: + * + * 1. In your driver (typically in the probe function) add an ATR by + * calling i2c_atr_new() passing your attach/detach callbacks + * 2. When the attach callback is called pick an appropriate alias, + * configure it in your chip and return the chosen alias in the + * alias_id parameter + * 3. When the detach callback is called, deconfigure the alias from + * your chip and put it back in the pool for later usage + * + * Originally based on i2c-mux.c + */ + +#include +#include +#include +#include +#include +#include +#include + +/** + * struct i2c_atr_cli2alias_pair - Hold 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_cli2alias_pair { + struct list_head node; + const struct i2c_client *client; + u16 alias; +}; + +/* + * Data for each channel (child bus) + */ +struct i2c_atr_chan { + struct i2c_adapter adap; + struct i2c_atr *atr; + u32 chan_id; + + struct list_head alias_list; + + u16 *orig_addrs; + unsigned int orig_addrs_size; + struct mutex orig_addrs_lock; /* Lock orig_addrs during xfer */ +}; + +static struct i2c_atr_cli2alias_pair * +i2c_atr_find_mapping_by_client(struct list_head *list, + struct i2c_client *client) +{ + struct i2c_atr_cli2alias_pair *c2a; + + list_for_each_entry(c2a, list, node) { + if (c2a->client == client) + return c2a; + } + + return NULL; +} + +static struct i2c_atr_cli2alias_pair * +i2c_atr_find_mapping_by_addr(struct list_head *list, + u16 phys_addr) +{ + struct i2c_atr_cli2alias_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_cli2alias_pair *c2a; + int i; + + /* Ensure we have enough room to save the original addresses */ + if (unlikely(chan->orig_addrs_size < num)) { + void *new_buf = kmalloc(num * sizeof(chan->orig_addrs[0]), + GFP_KERNEL); + if (new_buf == NULL) + 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) { + msgs[i].addr = c2a->alias; + } else { + dev_err(atr->dev, "client 0x%02x not mapped!\n", + msgs[i].addr); + return -ENXIO; + } + } + + return 0; +} + +/* + * Restore all message address aliases with the original addresses. + * + * This function is internal for use in i2c_atr_master_xfer(). + * + * @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 = 0; + + /* Switch to the right atr port */ + if (atr->ops->select) { + ret = atr->ops->select(atr, chan->chan_id); + if (ret < 0) + goto out; + } + + /* Translate addresses */ + mutex_lock(&chan->orig_addrs_lock); + ret = i2c_atr_map_msgs(chan, msgs, num); + if (ret < 0) { + mutex_unlock(&chan->orig_addrs_lock); + goto out; + } + + /* Perform the transfer */ + ret = i2c_transfer(parent, msgs, num); + + /* Restore addresses */ + i2c_atr_unmap_msgs(chan, msgs, num); + mutex_unlock(&chan->orig_addrs_lock); + +out: + if (atr->ops->deselect) + atr->ops->deselect(atr, chan->chan_id); + + 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_cli2alias_pair *c2a; + int err = 0; + + 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; + } + + if (atr->ops->select) + err = atr->ops->select(atr, chan->chan_id); + if (!err) + err = i2c_smbus_xfer(parent, c2a->alias, flags, + read_write, command, size, data); + if (atr->ops->deselect) + atr->ops->deselect(atr, chan->chan_id); + + return err; +} + +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_attach_client(struct i2c_adapter *adapter, + const struct i2c_board_info *info, + const struct i2c_client *client) +{ + struct i2c_atr_chan *chan = adapter->algo_data; + struct i2c_atr *atr = chan->atr; + struct i2c_atr_cli2alias_pair *c2a; + u16 alias_id = 0; + int err = 0; + + c2a = kzalloc(sizeof(struct i2c_atr_cli2alias_pair), GFP_KERNEL); + if (!c2a) { + err = -ENOMEM; + goto err_alloc; + } + + err = atr->ops->attach_client(atr, chan->chan_id, info, client, + &alias_id); + if (err) + goto err_attach; + if (alias_id == 0) { + err = -EINVAL; + goto err_attach; + } + + c2a->client = client; + c2a->alias = alias_id; + list_add(&c2a->node, &chan->alias_list); + + return 0; + +err_attach: + kfree(c2a); +err_alloc: + return err; +} + +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_cli2alias_pair *c2a; + + atr->ops->detach_client(atr, chan->chan_id, client); + + c2a = i2c_atr_find_mapping_by_client(&chan->alias_list, client); + if (c2a != NULL) { + list_del(&c2a->node); + kfree(c2a); + } +} + +static const struct i2c_attach_operations i2c_atr_attach_ops = { + .attach_client = i2c_atr_attach_client, + .detach_client = i2c_atr_detach_client, +}; + +/** + * 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`. + * + * After calling this function a new i2c bus will appear. Adding and + * removing devices on the downstream bus will result in calls to the + * `attach_client` and `detach_client` callbacks for the driver to assign + * an alias to the device. + * + * If there is a device tree node under "i2c-atr" whose "reg" property + * equals chan_id, the new adapter will receive that node and perhaps start + * adding devices under it. The callbacks for those additions will be made + * before i2c_atr_add_adapter() returns. + * + * 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 i2c_adapter *parent = atr->parent; + struct device *dev = atr->dev; + struct i2c_atr_chan *chan; + char symlink_name[20]; + int err; + + if (chan_id >= atr->max_adapters) + 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; + + 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 = dev; + chan->adap.retries = parent->retries; + chan->adap.timeout = parent->timeout; + chan->adap.quirks = parent->quirks; + chan->adap.lock_ops = &i2c_atr_lock_ops; + chan->adap.attach_ops = &i2c_atr_attach_ops; + + if (dev->of_node) { + struct device_node *atr_node; + struct device_node *child; + u32 reg; + + atr_node = of_get_child_by_name(dev->of_node, "i2c-atr"); + + for_each_child_of_node(atr_node, child) { + err = of_property_read_u32(child, "reg", ®); + if (err) + continue; + if (chan_id == reg) + break; + } + + chan->adap.dev.of_node = child; + of_node_put(atr_node); + } + + err = i2c_add_adapter(&chan->adap); + if (err) { + dev_err(dev, "failed to add atr-adapter %u (error=%d)\n", + chan_id, err); + goto err_add_adapter; + } + + WARN(sysfs_create_link(&chan->adap.dev.kobj, &dev->kobj, "atr_device"), + "can't create symlink to atr device\n"); + snprintf(symlink_name, sizeof(symlink_name), "channel-%u", chan_id); + WARN(sysfs_create_link(&dev->kobj, &chan->adap.dev.kobj, symlink_name), + "can't create symlink for channel %u\n", chan_id); + + dev_info(dev, "Added ATR child bus %d\n", i2c_adapter_id(&chan->adap)); + + atr->adapter[chan_id] = &chan->adap; + return 0; + +err_add_adapter: + mutex_destroy(&chan->orig_addrs_lock); + kfree(chan); + return err; +} +EXPORT_SYMBOL_GPL(i2c_atr_add_adapter); + +/** + * i2c_atr_del_adapter - Remove a child ("downstream") I2C bus added by + * i2c_atr_del_adapter(). + * @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) +{ + char symlink_name[20]; + + struct i2c_adapter *adap = atr->adapter[chan_id]; + struct i2c_atr_chan *chan = adap->algo_data; + struct device_node *np = adap->dev.of_node; + struct device *dev = atr->dev; + + if (atr->adapter[chan_id] == NULL) { + dev_err(dev, "Adapter %d does not exist\n", chan_id); + return; + } + + dev_info(dev, "Removing ATR child bus %d\n", i2c_adapter_id(adap)); + + atr->adapter[chan_id] = NULL; + + 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); + of_node_put(np); + mutex_destroy(&chan->orig_addrs_lock); + kfree(chan); +} +EXPORT_SYMBOL_GPL(i2c_atr_del_adapter); + +/** + * 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) +{ + struct i2c_atr *atr; + + if (!ops || !ops->attach_client || !ops->detach_client) + return ERR_PTR(-EINVAL); + + atr = devm_kzalloc(dev, sizeof(*atr) + + max_adapters * sizeof(atr->adapter[0]), + GFP_KERNEL); + if (!atr) + return ERR_PTR(-ENOMEM); + + mutex_init(&atr->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; + + return atr; +} +EXPORT_SYMBOL_GPL(i2c_atr_new); + +/** + * 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() mumst be + * removed by calling i2c_atr_del_adapter(). + */ +void i2c_atr_delete(struct i2c_atr *atr) +{ + mutex_destroy(&atr->lock); +} +EXPORT_SYMBOL_GPL(i2c_atr_delete); + +MODULE_AUTHOR("Luca Ceresoli "); +MODULE_DESCRIPTION("I2C Address Translator"); +MODULE_LICENSE("GPL v2"); diff --git a/include/linux/i2c-atr.h b/include/linux/i2c-atr.h new file mode 100644 index 000000000000..019816e5a50c --- /dev/null +++ b/include/linux/i2c-atr.h @@ -0,0 +1,82 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/** + * drivers/i2c/i2c-atr.h -- I2C Address Translator + * + * Copyright (c) 2019 Luca Ceresoli + * + * Based on i2c-mux.h + */ + +#ifndef _LINUX_I2C_ATR_H +#define _LINUX_I2C_ATR_H + +#ifdef __KERNEL__ + +#include +#include + +struct i2c_atr; + +/** + * struct i2c_atr_ops - Callbacks from ATR to the device driver. + * @select: Ask the driver to select a child bus (optional) + * @deselect: Ask the driver to deselect a child bus (optional) + * @attach_client: Notify the driver of a new device connected on a child + * bus. The driver must choose an I2C alias, configure the + * hardware to use it and return it in `alias_id`. + * @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 (*select)(struct i2c_atr *atr, u32 chan_id); + int (*deselect)(struct i2c_atr *atr, u32 chan_id); + int (*attach_client)(struct i2c_atr *atr, u32 chan_id, + const struct i2c_board_info *info, + const struct i2c_client *client, + u16 *alias_id); + void (*detach_client)(struct i2c_atr *atr, u32 chan_id, + const struct i2c_client *client); +}; + +/** + * Helper to add I2C ATR features to a device driver. + */ +struct i2c_atr { + /* private: internal use only */ + + struct i2c_adapter *parent; + struct device *dev; + const struct i2c_atr_ops *ops; + + void *priv; + + struct i2c_algorithm algo; + struct mutex lock; + int max_adapters; + + struct i2c_adapter *adapter[0]; +}; + +struct i2c_atr *i2c_atr_new(struct i2c_adapter *parent, struct device *dev, + const struct i2c_atr_ops *ops, int max_adapters); +void i2c_atr_delete(struct i2c_atr *atr); + +static inline void i2c_atr_set_clientdata(struct i2c_atr *atr, void *data) +{ + atr->priv = data; +} + +static inline void *i2c_atr_get_clientdata(struct i2c_atr *atr) +{ + return atr->priv; +} + +int i2c_atr_add_adapter(struct i2c_atr *atr, u32 chan_id); +void i2c_atr_del_adapter(struct i2c_atr *atr, u32 chan_id); + +#endif /* __KERNEL__ */ + +#endif /* _LINUX_I2C_ATR_H */ -- 2.17.1