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([188.163.112.79]) by smtp.gmail.com with ESMTPSA id r13-20020aa7d58d000000b00514b2a9ce60sm13073283edq.81.2023.06.19.07.36.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Jun 2023 07:36:31 -0700 (PDT) From: Svyatoslav Ryhel To: Andi Shyti , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Wolfram Sang , =?utf-8?b?TWljaGHFgiBNaXJvc8WCYXc=?= , Svyatoslav Ryhel Cc: linux-i2c@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v1 2/2] i2c: Add GPIO-based hotplug gate Date: Mon, 19 Jun 2023 17:36:11 +0300 Message-Id: <20230619143611.24482-3-clamor95@gmail.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230619143611.24482-1-clamor95@gmail.com> References: <20230619143611.24482-1-clamor95@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_ENVFROM_END_DIGIT, FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org From: Michał Mirosław Implement driver for hot-plugged I2C busses, where some devices on a bus are hot-pluggable and their presence is indicated by GPIO line. Co-developed-by: Ion Agorria Signed-off-by: Ion Agorria Signed-off-by: Michał Mirosław Signed-off-by: Svyatoslav Ryhel --- drivers/i2c/Kconfig | 11 ++ drivers/i2c/Makefile | 1 + drivers/i2c/i2c-hotplug-gpio.c | 266 +++++++++++++++++++++++++++++++++ 3 files changed, 278 insertions(+) create mode 100644 drivers/i2c/i2c-hotplug-gpio.c diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig index 438905e2a1d0..3e3f7675ea4a 100644 --- a/drivers/i2c/Kconfig +++ b/drivers/i2c/Kconfig @@ -98,6 +98,17 @@ config I2C_SMBUS source "drivers/i2c/algos/Kconfig" source "drivers/i2c/busses/Kconfig" +config I2C_HOTPLUG_GPIO + tristate "Hot-plugged I2C bus detected by GPIO" + depends on GPIOLIB + depends on OF + help + If you say yes to this option, support will be included for + hot-plugging I2C devices with presence detected by GPIO pin value. + + This driver can also be built as a module. If so, the module + will be called i2c-hotplug-gpio. + config I2C_STUB tristate "I2C/SMBus Test Stub" depends on m diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile index c1d493dc9bac..9fd44310835a 100644 --- a/drivers/i2c/Makefile +++ b/drivers/i2c/Makefile @@ -14,6 +14,7 @@ obj-$(CONFIG_I2C_SMBUS) += i2c-smbus.o obj-$(CONFIG_I2C_CHARDEV) += i2c-dev.o obj-$(CONFIG_I2C_MUX) += i2c-mux.o obj-y += algos/ busses/ muxes/ +obj-$(CONFIG_I2C_HOTPLUG_GPIO) += i2c-hotplug-gpio.o obj-$(CONFIG_I2C_STUB) += i2c-stub.o obj-$(CONFIG_I2C_SLAVE_EEPROM) += i2c-slave-eeprom.o obj-$(CONFIG_I2C_SLAVE_TESTUNIT) += i2c-slave-testunit.o diff --git a/drivers/i2c/i2c-hotplug-gpio.c b/drivers/i2c/i2c-hotplug-gpio.c new file mode 100644 index 000000000000..18c2d7f44d29 --- /dev/null +++ b/drivers/i2c/i2c-hotplug-gpio.c @@ -0,0 +1,266 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * I2C hotplug gate controlled by GPIO + */ + +#include +#include +#include +#include +#include +#include +#include + +struct i2c_hotplug_priv { + struct i2c_adapter adap; + struct i2c_adapter *parent; + struct device *dev; + struct gpio_desc *gpio; + int irq; +}; + +static inline struct i2c_adapter *i2c_hotplug_parent(struct i2c_adapter *adap) +{ + struct i2c_hotplug_priv *priv = container_of(adap, struct i2c_hotplug_priv, adap); + + return priv->parent; +} + +static int i2c_hotplug_master_xfer(struct i2c_adapter *adap, + struct i2c_msg msgs[], int num) +{ + struct i2c_adapter *parent = i2c_hotplug_parent(adap); + + return parent->algo->master_xfer(parent, msgs, num); +} + +static int i2c_hotplug_smbus_xfer(struct i2c_adapter *adap, u16 addr, + unsigned short flags, char read_write, + u8 command, int protocol, + union i2c_smbus_data *data) +{ + struct i2c_adapter *parent = i2c_hotplug_parent(adap); + + return parent->algo->smbus_xfer(parent, addr, flags, read_write, + command, protocol, data); +} + +static u32 i2c_hotplug_functionality(struct i2c_adapter *adap) +{ + u32 parent_func = i2c_get_functionality(i2c_hotplug_parent(adap)); + + return parent_func & ~I2C_FUNC_SLAVE; +} + +static const struct i2c_algorithm i2c_hotplug_algo_i2c = { + .master_xfer = i2c_hotplug_master_xfer, + .functionality = i2c_hotplug_functionality, +}; + +static const struct i2c_algorithm i2c_hotplug_algo_smbus = { + .smbus_xfer = i2c_hotplug_smbus_xfer, + .functionality = i2c_hotplug_functionality, +}; + +static const struct i2c_algorithm i2c_hotplug_algo_both = { + .master_xfer = i2c_hotplug_master_xfer, + .smbus_xfer = i2c_hotplug_smbus_xfer, + .functionality = i2c_hotplug_functionality, +}; + +static const struct i2c_algorithm *const i2c_hotplug_algo[2][2] = { + /* non-I2C */ + { NULL, &i2c_hotplug_algo_smbus }, + /* I2C */ + { &i2c_hotplug_algo_i2c, &i2c_hotplug_algo_both } +}; + +static void i2c_hotplug_lock_bus(struct i2c_adapter *adap, unsigned int flags) +{ + i2c_lock_bus(i2c_hotplug_parent(adap), flags); +} + +static int i2c_hotplug_trylock_bus(struct i2c_adapter *adap, + unsigned int flags) +{ + return i2c_trylock_bus(i2c_hotplug_parent(adap), flags); +} + +static void i2c_hotplug_unlock_bus(struct i2c_adapter *adap, + unsigned int flags) +{ + i2c_unlock_bus(i2c_hotplug_parent(adap), flags); +} + +static const struct i2c_lock_operations i2c_hotplug_lock_ops = { + .lock_bus = i2c_hotplug_lock_bus, + .trylock_bus = i2c_hotplug_trylock_bus, + .unlock_bus = i2c_hotplug_unlock_bus, +}; + +static int i2c_hotplug_recover_bus(struct i2c_adapter *adap) +{ + return i2c_recover_bus(i2c_hotplug_parent(adap)); +} + +static struct i2c_bus_recovery_info i2c_hotplug_recovery_info = { + .recover_bus = i2c_hotplug_recover_bus, +}; + +static int i2c_hotplug_activate(struct i2c_hotplug_priv *priv) +{ + int ret; + + if (priv->adap.algo_data) + return 0; + + /* + * Store the dev data in adapter dev, since + * previous i2c_del_adapter might have wiped it. + */ + priv->adap.dev.parent = priv->dev; + priv->adap.dev.of_node = priv->dev->of_node; + + dev_dbg(priv->adap.dev.parent, "connection detected"); + + ret = i2c_add_adapter(&priv->adap); + if (!ret) + priv->adap.algo_data = (void *)1; + + return ret; +} + +static void i2c_hotplug_deactivate(struct i2c_hotplug_priv *priv) +{ + if (!priv->adap.algo_data) + return; + + dev_dbg(priv->adap.dev.parent, "disconnection detected"); + + i2c_del_adapter(&priv->adap); + priv->adap.algo_data = NULL; +} + +static irqreturn_t i2c_hotplug_interrupt(int irq, void *dev_id) +{ + struct i2c_hotplug_priv *priv = dev_id; + + /* debounce */ + msleep(20); + + if (gpiod_get_value_cansleep(priv->gpio)) + i2c_hotplug_activate(priv); + else + i2c_hotplug_deactivate(priv); + + return IRQ_HANDLED; +} + +static void devm_i2c_put_adapter(void *adapter) +{ + i2c_put_adapter(adapter); +} + +static int i2c_hotplug_gpio_probe(struct platform_device *pdev) +{ + struct device_node *parent_np; + struct i2c_adapter *parent; + struct i2c_hotplug_priv *priv; + bool is_i2c, is_smbus; + int ret; + + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + platform_set_drvdata(pdev, priv); + priv->dev = &pdev->dev; + + parent_np = of_parse_phandle(pdev->dev.of_node, "i2c-parent", 0); + if (IS_ERR(parent_np)) + return dev_err_probe(&pdev->dev, PTR_ERR(parent_np), + "cannot parse i2c-parent\n"); + + parent = of_find_i2c_adapter_by_node(parent_np); + of_node_put(parent_np); + if (IS_ERR(parent)) + return dev_err_probe(&pdev->dev, PTR_ERR(parent), + "failed to get parent I2C adapter\n"); + priv->parent = parent; + + ret = devm_add_action_or_reset(&pdev->dev, devm_i2c_put_adapter, + parent); + if (ret) + return ret; + + priv->gpio = devm_gpiod_get(&pdev->dev, "detect", GPIOD_IN); + if (IS_ERR(priv->gpio)) + return dev_err_probe(&pdev->dev, PTR_ERR(priv->gpio), + "failed to get detect GPIO\n"); + + is_i2c = parent->algo->master_xfer; + is_smbus = parent->algo->smbus_xfer; + + snprintf(priv->adap.name, sizeof(priv->adap.name), + "i2c-hotplug (master i2c-%d)", i2c_adapter_id(parent)); + priv->adap.owner = THIS_MODULE; + priv->adap.algo = i2c_hotplug_algo[is_i2c][is_smbus]; + priv->adap.algo_data = NULL; + priv->adap.lock_ops = &i2c_hotplug_lock_ops; + priv->adap.class = parent->class; + priv->adap.retries = parent->retries; + priv->adap.timeout = parent->timeout; + priv->adap.quirks = parent->quirks; + if (parent->bus_recovery_info) + priv->adap.bus_recovery_info = &i2c_hotplug_recovery_info; + + if (!priv->adap.algo) + return -EINVAL; + + priv->irq = platform_get_irq(pdev, 0); + if (priv->irq < 0) + return dev_err_probe(&pdev->dev, priv->irq, + "failed to get IRQ %d\n", priv->irq); + + ret = devm_request_threaded_irq(&pdev->dev, priv->irq, NULL, + i2c_hotplug_interrupt, + IRQF_ONESHOT | IRQF_SHARED, + "i2c-hotplug", priv); + if (ret) + return dev_err_probe(&pdev->dev, ret, + "failed to register IRQ %d\n", priv->irq); + + irq_wake_thread(priv->irq, priv); + + return 0; +} + +static int i2c_hotplug_gpio_remove(struct platform_device *pdev) +{ + struct i2c_hotplug_priv *priv = platform_get_drvdata(pdev); + + i2c_hotplug_deactivate(priv); + + return 0; +} + +static const struct of_device_id i2c_hotplug_gpio_of_match[] = { + { .compatible = "i2c-hotplug-gpio" }, + {}, +}; +MODULE_DEVICE_TABLE(of, i2c_hotplug_gpio_of_match); + +static struct platform_driver i2c_hotplug_gpio_driver = { + .probe = i2c_hotplug_gpio_probe, + .remove = i2c_hotplug_gpio_remove, + .driver = { + .name = "i2c-hotplug-gpio", + .of_match_table = i2c_hotplug_gpio_of_match, + }, +}; + +module_platform_driver(i2c_hotplug_gpio_driver); + +MODULE_DESCRIPTION("Hot-plugged I2C bus detected by GPIO"); +MODULE_AUTHOR("Michał Mirosław "); +MODULE_LICENSE("GPL");