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Tue, 6 Sep 2022 20:28:31 +0000 (GMT) From: Eddie James To: linux-i2c@vger.kernel.org Cc: linux-iio@vger.kernel.org, wsa@kernel.org, peda@axentia.se, jic23@kernel.org, lars@metafoo.de, miltonm@us.ibm.com, joel@jms.id.au, eajames@linux.ibm.com, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/2] i2c: core: Add mux root adapter operations Date: Tue, 6 Sep 2022 15:28:28 -0500 Message-Id: <20220906202829.1921114-2-eajames@linux.ibm.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20220906202829.1921114-1-eajames@linux.ibm.com> References: <20220906202829.1921114-1-eajames@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: -shRQ9tfLptfra0eQAIhHJWtwGvcTWTI X-Proofpoint-GUID: -shRQ9tfLptfra0eQAIhHJWtwGvcTWTI X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.528,FMLib:17.11.122.1 definitions=2022-09-06_09,2022-09-06_02,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 clxscore=1015 impostorscore=0 suspectscore=0 spamscore=0 phishscore=0 bulkscore=0 mlxlogscore=999 adultscore=0 malwarescore=0 lowpriorityscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2207270000 definitions=main-2209060093 X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_EF,RCVD_IN_MSPIKE_H2,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 Some I2C clients need the ability to control the root I2C bus even if the endpoint device is behind a mux. For example, a driver for a chip that can't handle any I2C traffic on the bus while coming out of reset (including an I2C-driven mux switching channels) may need to lock the root bus with the mux selection fixed for the entire time the device is in reset. For this purpose, add a new structure containing two function pointers to the adapter structure. These functions pointers should be defined for every adapter. The lock_select operation, for a mux adapter, locks the parent adpaters up to the root and selects the adapter's channel. The unlock_deselect operation deselects the mux channel and unlocks all the adapters. For a non-mux adapter, the operations lock and unlock the adapters up to the root. This scheme should work with multiple levels of muxes and regular adapters in between. Signed-off-by: Eddie James Reviewed-by: Joel Stanley --- drivers/i2c/i2c-core-base.c | 38 ++++++++++++++++++++++++++++ drivers/i2c/i2c-mux.c | 50 +++++++++++++++++++++++++++++++++++++ include/linux/i2c.h | 42 +++++++++++++++++++++++++++++++ 3 files changed, 130 insertions(+) diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c index 8c7e3494ca5f..b1a1e88ef478 100644 --- a/drivers/i2c/i2c-core-base.c +++ b/drivers/i2c/i2c-core-base.c @@ -1347,6 +1347,41 @@ static const struct i2c_lock_operations i2c_adapter_lock_ops = { .unlock_bus = i2c_adapter_unlock_bus, }; +/* + * For a non-mux adapter, the lock_select operation locks the chain of + * adapters upwards, returning the root. If there's a mux above this adapter + * somehow, it should also get locked and the desired channel selected. + */ +static struct i2c_adapter *i2c_adapter_lock_select(struct i2c_adapter *adapter) +{ + struct i2c_adapter *ret = adapter; + struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter); + + if (parent) { + ret = parent->mux_root_ops->lock_select(parent); + if (IS_ERR(ret)) + return ret; + } + + adapter->lock_ops->lock_bus(adapter, I2C_LOCK_ROOT_ADAPTER); + return ret; +} + +static void i2c_adapter_unlock_deselect(struct i2c_adapter *adapter) +{ + struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter); + + adapter->lock_ops->unlock_bus(adapter, I2C_LOCK_ROOT_ADAPTER); + + if (parent) + parent->mux_root_ops->unlock_deselect(parent); +} + +static const struct i2c_mux_root_operations i2c_adapter_mux_root_ops = { + .lock_select = i2c_adapter_lock_select, + .unlock_deselect = i2c_adapter_unlock_deselect, +}; + static void i2c_host_notify_irq_teardown(struct i2c_adapter *adap) { struct irq_domain *domain = adap->host_notify_domain; @@ -1442,6 +1477,9 @@ static int i2c_register_adapter(struct i2c_adapter *adap) if (!adap->lock_ops) adap->lock_ops = &i2c_adapter_lock_ops; + if (!adap->mux_root_ops) + adap->mux_root_ops = &i2c_adapter_mux_root_ops; + adap->locked_flags = 0; rt_mutex_init(&adap->bus_lock); rt_mutex_init(&adap->mux_lock); diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c index 774507b54b57..c7db770e4198 100644 --- a/drivers/i2c/i2c-mux.c +++ b/drivers/i2c/i2c-mux.c @@ -210,6 +210,49 @@ static void i2c_parent_unlock_bus(struct i2c_adapter *adapter, rt_mutex_unlock(&parent->mux_lock); } +/* + * For a mux adapter, the lock_select operation first locks just like the + * lock_bus operation. Then it selects the channel for this adapter and + * returns the root adapter. If there is another mux above this one, calling + * the parent lock_select should ensure that the channel is correctly + * selected. + */ +static struct i2c_adapter *i2c_mux_lock_select(struct i2c_adapter *adapter) +{ + int ret; + struct i2c_mux_priv *priv = adapter->algo_data; + struct i2c_mux_core *muxc = priv->muxc; + struct i2c_adapter *parent = muxc->parent; + + rt_mutex_lock_nested(&parent->mux_lock, i2c_adapter_depth(adapter)); + + adapter = parent->mux_root_ops->lock_select(parent); + if (IS_ERR(adapter)) + return adapter; + + ret = muxc->select(muxc, priv->chan_id); + if (ret < 0) { + parent->mux_root_ops->unlock_deselect(parent); + rt_mutex_unlock(&parent->mux_lock); + return ERR_PTR(ret); + } + + return adapter; +} + +static void i2c_mux_unlock_deselect(struct i2c_adapter *adapter) +{ + struct i2c_mux_priv *priv = adapter->algo_data; + struct i2c_mux_core *muxc = priv->muxc; + struct i2c_adapter *parent = muxc->parent; + + if (muxc->deselect) + muxc->deselect(muxc, priv->chan_id); + + parent->mux_root_ops->unlock_deselect(parent); + rt_mutex_unlock(&parent->mux_lock); +} + struct i2c_adapter *i2c_root_adapter(struct device *dev) { struct device *i2c; @@ -279,6 +322,11 @@ static const struct i2c_lock_operations i2c_parent_lock_ops = { .unlock_bus = i2c_parent_unlock_bus, }; +static const struct i2c_mux_root_operations i2c_mux_root_ops = { + .lock_select = i2c_mux_lock_select, + .unlock_deselect = i2c_mux_unlock_deselect, +}; + int i2c_mux_add_adapter(struct i2c_mux_core *muxc, u32 force_nr, u32 chan_id, unsigned int class) @@ -339,6 +387,8 @@ int i2c_mux_add_adapter(struct i2c_mux_core *muxc, else priv->adap.lock_ops = &i2c_parent_lock_ops; + priv->adap.mux_root_ops = &i2c_mux_root_ops; + /* Sanity check on class */ if (i2c_mux_parent_classes(parent) & class) dev_err(&parent->dev, diff --git a/include/linux/i2c.h b/include/linux/i2c.h index f7c49bbdb8a1..51342a0c03e9 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -584,6 +584,26 @@ struct i2c_lock_operations { void (*unlock_bus)(struct i2c_adapter *adapter, unsigned int flags); }; +/** + * struct i2c_mux_root_operations - represent operations to lock and select + * the adapter's mux channel (if a mux is present) + * @lock_select: Get exclusive access to the root I2C bus adapter with the + * correct mux channel selected for the adapter + * @unlock_deslect: Release exclusive access to the root I2C bus adapter and + * deselect the mux channel for the adapter + * + * Some I2C clients need the ability to control the root I2C bus even if the + * endpoint device is behind a mux. For example, a driver for a chip that + * can't handle any I2C traffic on the bus while coming out of reset (including + * an I2C-driven mux switching channels) may need to lock the root bus with + * the mux selection fixed for the entire time the device is in reset. + * These operations are for such a purpose. + */ +struct i2c_mux_root_operations { + struct i2c_adapter *(*lock_select)(struct i2c_adapter *adapter); + void (*unlock_deselect)(struct i2c_adapter *adapter); +}; + /** * struct i2c_timings - I2C timing information * @bus_freq_hz: the bus frequency in Hz @@ -726,6 +746,7 @@ struct i2c_adapter { /* data fields that are valid for all devices */ const struct i2c_lock_operations *lock_ops; + const struct i2c_mux_root_operations *mux_root_ops; struct rt_mutex bus_lock; struct rt_mutex mux_lock; @@ -818,6 +839,27 @@ i2c_unlock_bus(struct i2c_adapter *adapter, unsigned int flags) adapter->lock_ops->unlock_bus(adapter, flags); } +/** + * i2c_lock_select_bus - Get exclusive access to the root I2C bus with the + * target's mux channel (if a mux is present) selected. + * @adapter: Target I2C bus + * + * Return the root I2C bus if mux selection succeeds, an ERR_PTR otherwise + */ +static inline struct i2c_adapter *i2c_lock_select_bus(struct i2c_adapter *adapter) +{ + return adapter->mux_root_ops->lock_select(adapter); +} + +/** + * i2c_unlock_deselect_bus - Release exclusive access to the root I2C bus + * @adapter: Target I2C bus + */ +static inline void i2c_unlock_deselect_bus(struct i2c_adapter *adapter) +{ + adapter->mux_root_ops->unlock_deselect(adapter); +} + /** * i2c_mark_adapter_suspended - Report suspended state of the adapter to the core * @adap: Adapter to mark as suspended From patchwork Tue Sep 6 20:28:29 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eddie James X-Patchwork-Id: 1675028 X-Patchwork-Delegate: patchwork@peda.user.lysator.liu.se Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=2620:137:e000::1:20; helo=out1.vger.email; envelope-from=linux-i2c-owner@vger.kernel.org; receiver=) Authentication-Results: legolas.ozlabs.org; dkim=pass (2048-bit key; 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Tue, 06 Sep 2022 20:28:33 +0000 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp22033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 286KSWm564029126 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 6 Sep 2022 20:28:32 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BD3FAB205F; Tue, 6 Sep 2022 20:28:32 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 06495B2064; Tue, 6 Sep 2022 20:28:32 +0000 (GMT) Received: from slate16.aus.stglabs.ibm.com (unknown [9.160.74.237]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Tue, 6 Sep 2022 20:28:31 +0000 (GMT) From: Eddie James To: linux-i2c@vger.kernel.org Cc: linux-iio@vger.kernel.org, wsa@kernel.org, peda@axentia.se, jic23@kernel.org, lars@metafoo.de, miltonm@us.ibm.com, joel@jms.id.au, eajames@linux.ibm.com, linux-kernel@vger.kernel.org Subject: [PATCH v2 2/2] iio: si7020: Lock root adapter to wait for reset Date: Tue, 6 Sep 2022 15:28:29 -0500 Message-Id: <20220906202829.1921114-3-eajames@linux.ibm.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20220906202829.1921114-1-eajames@linux.ibm.com> References: <20220906202829.1921114-1-eajames@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: F1s0qnT7hEyeGhvNn2CNWwTC5NdotSJs X-Proofpoint-ORIG-GUID: F1s0qnT7hEyeGhvNn2CNWwTC5NdotSJs X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.528,FMLib:17.11.122.1 definitions=2022-09-06_09,2022-09-06_02,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 priorityscore=1501 suspectscore=0 bulkscore=0 lowpriorityscore=0 spamscore=0 malwarescore=0 adultscore=0 mlxlogscore=999 clxscore=1015 phishscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2207270000 definitions=main-2209060093 X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_EF,RCVD_IN_MSPIKE_H2,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 Use the new mux root operations to lock the root adapter while waiting for the reset to complete. I2C commands issued after the SI7020 is starting up or after reset can potentially upset the startup sequence. Therefore, the host needs to wait for the startup sequence to finish before issuing further I2C commands. Signed-off-by: Eddie James --- drivers/iio/humidity/si7020.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/drivers/iio/humidity/si7020.c b/drivers/iio/humidity/si7020.c index ab6537f136ba..76ca7863f35b 100644 --- a/drivers/iio/humidity/si7020.c +++ b/drivers/iio/humidity/si7020.c @@ -106,6 +106,7 @@ static const struct iio_info si7020_info = { static int si7020_probe(struct i2c_client *client, const struct i2c_device_id *id) { + struct i2c_adapter *root; struct iio_dev *indio_dev; struct i2c_client **data; int ret; @@ -115,13 +116,24 @@ static int si7020_probe(struct i2c_client *client, I2C_FUNC_SMBUS_READ_WORD_DATA)) return -EOPNOTSUPP; + root = i2c_lock_select_bus(client->adapter); + if (IS_ERR(root)) + return PTR_ERR(root); + /* Reset device, loads default settings. */ - ret = i2c_smbus_write_byte(client, SI7020CMD_RESET); - if (ret < 0) + ret = __i2c_smbus_xfer(root, client->addr, client->flags, + I2C_SMBUS_WRITE, SI7020CMD_RESET, + I2C_SMBUS_BYTE, NULL); + if (ret < 0) { + i2c_unlock_deselect_bus(client->adapter); return ret; + } + /* Wait the maximum power-up time after software reset. */ msleep(15); + i2c_unlock_deselect_bus(client->adapter); + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); if (!indio_dev) return -ENOMEM;