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[209.132.180.67]) by mx.google.com with ESMTP id v89si26103130pjb.14.2019.06.05.10.03.42; Wed, 05 Jun 2019 10:04:00 -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; dkim=pass header.i=@gmail.com header.s=20161025 header.b=NoVo2w4W; 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; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728819AbfFERCY (ORCPT + 99 others); Wed, 5 Jun 2019 13:02:24 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:38870 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728729AbfFERCX (ORCPT ); Wed, 5 Jun 2019 13:02:23 -0400 Received: by mail-pg1-f195.google.com with SMTP id v11so12723570pgl.5; Wed, 05 Jun 2019 10:02:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=gwq0oyAiNi9hUTrg8K9KARl5Rv2m1zkNF1Qs8OEvG/c=; b=NoVo2w4WN4+BDlTriH2nMiW01Fuo8Rx7e+niflRm6RrNpv5oJeCzu8HdGBCfHe/z4X 6szGF5kBBuQLVl48X/4la46ISLFRnaZmmxjSjg5y2dfq4H5Fvfv5Rdtb1dLdIiZe7Mpr dxoUctCvO6rjWZnBojpvbxCtk2kiKbJd6qTH4i5sahs8pUdj0f6d28ei4PREsf0bO6cW n8loJlaQ3pmxvtBfeg+b6D/rkRLlQJZLUjZKPCu69W/h/Sj72+yd24J4VLv9L1UbDm3Z NT/9z7nIV6GFk4p0OcIKgm0YasYPxfCtUtibiOVTMw/LJmP4oHSgAgxuqWsACoATg6D0 Y+Iw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=gwq0oyAiNi9hUTrg8K9KARl5Rv2m1zkNF1Qs8OEvG/c=; b=SQFe9fxofQv89dZy8wV9hrWEz7LV41HZswfXm/NtFeZsknVPQL4CW66e8c3jJJBuZf vNf6cEQXuoVVINeZmW5do0cyvAzkFHs9ZhErerzg36OimkM1A0bStkyCm8y5XCfiUAyJ KXOyKTq7PvUHyj5kqJC9NOhzhIOxClaLQau5HhYkrhxCDXkrdx9uLuMsJzOtJry6wPlp r9GWAMPKe+pq5oYPS7CTxQxirFRDu96zsRLtx4fNsEcYMSegcv0iisYUJFi0QqeiWqva T578XZjq6sjSY7BHY9EluSldRXvPZFYnKT0c/tCdUW+KdkpCIGiBsBvbXW73q//PKYlS /TGQ== X-Gm-Message-State: APjAAAXPCmYHJWhoiiJ0kbLe74G+vhQ+Xdt7LJM3J/YMDKnkOBR5tqP5 2w5u9EhVMOOhY/ZBRJFMWdjlHPGHkAbJl75i+DY= X-Received: by 2002:a63:fb05:: with SMTP id o5mr6004598pgh.203.1559754142264; Wed, 05 Jun 2019 10:02:22 -0700 (PDT) MIME-Version: 1.0 References: <20190605164651.15991-1-eduval@amazon.com> <20190605164651.15991-3-eduval@amazon.com> In-Reply-To: <20190605164651.15991-3-eduval@amazon.com> From: Andy Shevchenko Date: Wed, 5 Jun 2019 20:02:11 +0300 Message-ID: Subject: Re: [PATCHv7 2/3] i2c: slave-mqueue: add a slave backend to receive and queue messages To: Eduardo Valentin Cc: Wolfram Sang , Haiyue Wang , Jarkko Nikula , Andriy Shevchenko , Brendan Higgins , Rob Herring , Mark Rutland , linux-i2c , devicetree , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 5, 2019 at 7:48 PM Eduardo Valentin wrote: > > From: Haiyue Wang > > Some protocols over I2C are designed for bi-directional transferring > messages by using I2C Master Write protocol. Like the MCTP (Management > Component Transport Protocol) and IPMB (Intelligent Platform Management > Bus), they both require that the userspace can receive messages from > I2C dirvers under slave mode. > > This new slave mqueue backend is used to receive and queue messages, it > will exposes these messages to userspace by sysfs bin file. > > Note: DT interface and a couple of minor fixes here and there > by Eduardo, so I kept the original authorship here. FWIW, Reviewed-by: Andy Shevchenko though I prefer simple dropping of of_match_ptr(), and by the way, #include is superfluous and may be changed to mod_devicetable.h. Leave above to Wolfram to judge. > Cc: Rob Herring > Cc: Mark Rutland > Cc: Wolfram Sang > Cc: Andy Shevchenko > Cc: linux-i2c@vger.kernel.org > Cc: devicetree@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Haiyue Wang > Signed-off-by: Eduardo Valentin > --- > > From V6 -> V7: > - fixed compile warm when CONFIG_OF=n by wrapping of table into ifdef > - minor changes: kobj_to_dev(), moved BUILD_BUG_ON() to start of function, > and flagged DT table sentinel in a more strict way. > - Also added a MODULE_DEVICE_TABLE() for the of table. > > Documentation/i2c/slave-mqueue-backend.rst | 124 ++++++++++++ > MAINTAINERS | 8 + > drivers/i2c/Kconfig | 25 +++ > drivers/i2c/Makefile | 1 + > drivers/i2c/i2c-slave-mqueue.c | 215 +++++++++++++++++++++ > 5 files changed, 373 insertions(+) > create mode 100644 Documentation/i2c/slave-mqueue-backend.rst > create mode 100644 drivers/i2c/i2c-slave-mqueue.c > > diff --git a/Documentation/i2c/slave-mqueue-backend.rst b/Documentation/i2c/slave-mqueue-backend.rst > new file mode 100644 > index 000000000000..376dff998fa3 > --- /dev/null > +++ b/Documentation/i2c/slave-mqueue-backend.rst > @@ -0,0 +1,124 @@ > +.. SPDX-License-Identifier: GPL-2.0 > + > +===================================== > +Linux I2C slave message queue backend > +===================================== > + > +:Author: Haiyue Wang > + > +Some protocols over I2C/SMBus are designed for bi-directional transferring > +messages by using I2C Master Write protocol. This requires that both sides > +of the communication have slave addresses. > + > +Like MCTP (Management Component Transport Protocol) and IPMB (Intelligent > +Platform Management Bus), they both require that the userspace can receive > +messages from i2c drivers under slave mode. > + > +This I2C slave mqueue (message queue) backend is used to receive and queue > +messages from the remote i2c intelligent device; and it will add the target > +slave address (with R/W# bit is always 0) into the message at the first byte, > +so that userspace can use this byte to dispatch the messages into different > +handling modules. Also, like IPMB, the address byte is in its message format, > +it needs it to do checksum. > + > +For messages are time related, so this backend will flush the oldest message > +to queue the newest one. > + > +Link > +---- > +`Intelligent Platform Management Bus > +Communications Protocol Specification > +`_ > + > +`Management Component Transport Protocol (MCTP) > +SMBus/I2C Transport Binding Specification > +`_ > + > +How to use > +---------- > +For example, the I2C5 bus has slave address 0x10, the below command will create > +the related message queue interface: > + > + echo slave-mqueue 0x1010 > /sys/bus/i2c/devices/i2c-5/new_device > + > +Then you can dump the messages like this: > + > + hexdump -C /sys/bus/i2c/devices/5-1010/slave-mqueue > + > +Code Example > +------------ > +*Note: call 'lseek' before 'read', this is a requirement from kernfs' design.* > + > +:: > + > + #include > + #include > + #include > + #include > + #include > + #include > + #include > + > + int main(int argc, char *argv[]) > + { > + int i, r; > + struct pollfd pfd; > + struct timespec ts; > + unsigned char data[256]; > + > + pfd.fd = open(argv[1], O_RDONLY | O_NONBLOCK); > + if (pfd.fd < 0) > + return -1; > + > + pfd.events = POLLPRI; > + > + while (1) { > + r = poll(&pfd, 1, 5000); > + > + if (r < 0) > + break; > + > + if (r == 0 || !(pfd.revents & POLLPRI)) > + continue; > + > + lseek(pfd.fd, 0, SEEK_SET); > + r = read(pfd.fd, data, sizeof(data)); > + if (r <= 0) > + continue; > + > + clock_gettime(CLOCK_MONOTONIC, &ts); > + printf("[%ld.%.9ld] :", ts.tv_sec, ts.tv_nsec); > + for (i = 0; i < r; i++) > + printf(" %02x", data[i]); > + printf("\n"); > + } > + > + close(pfd.fd); > + > + return 0; > + } > + > +Result > +------ > +*./a.out "/sys/bus/i2c/devices/5-1010/slave-mqueue"* > + > +:: > + > + [10183.232500449] : 20 18 c8 2c 78 01 5b > + [10183.479358348] : 20 18 c8 2c 78 01 5b > + [10183.726556812] : 20 18 c8 2c 78 01 5b > + [10183.972605863] : 20 18 c8 2c 78 01 5b > + [10184.220124772] : 20 18 c8 2c 78 01 5b > + [10184.467764166] : 20 18 c8 2c 78 01 5b > + [10193.233421784] : 20 18 c8 2c 7c 01 57 > + [10193.480273460] : 20 18 c8 2c 7c 01 57 > + [10193.726788733] : 20 18 c8 2c 7c 01 57 > + [10193.972781945] : 20 18 c8 2c 7c 01 57 > + [10194.220487360] : 20 18 c8 2c 7c 01 57 > + [10194.468089259] : 20 18 c8 2c 7c 01 57 > + [10203.233433099] : 20 18 c8 2c 80 01 53 > + [10203.481058715] : 20 18 c8 2c 80 01 53 > + [10203.727610472] : 20 18 c8 2c 80 01 53 > + [10203.974044856] : 20 18 c8 2c 80 01 53 > + [10204.220734634] : 20 18 c8 2c 80 01 53 > + [10204.468461664] : 20 18 c8 2c 80 01 53 > diff --git a/MAINTAINERS b/MAINTAINERS > index a6954776a37e..4bfca09a5f68 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -7458,6 +7458,14 @@ L: linux-i2c@vger.kernel.org > S: Maintained > F: drivers/i2c/i2c-stub.c > > +I2C SLAVE MQUEUE DRIVER > +M: Eduardo Valentin > +L: linux-i2c@vger.kernel.org > +S: Maintained > +F: drivers/i2c/i2c-slave-mqueue.c > +F: Documentation/i2c/slave-mqueue-backend.rst > +F: Documentation/devicetree/bindings/i2c/i2c-slave-mqueue.txt > + > I3C SUBSYSTEM > M: Boris Brezillon > L: linux-i3c@lists.infradead.org > diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig > index abedd55a1264..f335924936ae 100644 > --- a/drivers/i2c/Kconfig > +++ b/drivers/i2c/Kconfig > @@ -119,6 +119,31 @@ if I2C_SLAVE > config I2C_SLAVE_EEPROM > tristate "I2C eeprom slave driver" > > +config I2C_SLAVE_MQUEUE > + tristate "I2C mqueue (message queue) slave driver" > + help > + Some protocols over I2C are designed for bi-directional transferring > + messages by using I2C Master Write protocol. This driver is used to > + receive and queue messages from the remote I2C device. > + > + Userspace can get the messages by reading sysfs file that this driver > + exposes. > + > + This support is also available as a module. If so, the module will be > + called i2c-slave-mqueue. > + > +config I2C_SLAVE_MQUEUE_MESSAGE_SIZE > + int "The message size of I2C mqueue slave" > + depends on I2C_SLAVE_MQUEUE > + default 120 > + > +config I2C_SLAVE_MQUEUE_QUEUE_SIZE > + int "The queue size of I2C mqueue slave" > + depends on I2C_SLAVE_MQUEUE > + default 32 > + help > + This number MUST be power of 2. > + > endif > > config I2C_DEBUG_CORE > diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile > index bed6ba63c983..9a31bc75a446 100644 > --- a/drivers/i2c/Makefile > +++ b/drivers/i2c/Makefile > @@ -16,5 +16,6 @@ obj-$(CONFIG_I2C_MUX) += i2c-mux.o > obj-y += algos/ busses/ muxes/ > obj-$(CONFIG_I2C_STUB) += i2c-stub.o > obj-$(CONFIG_I2C_SLAVE_EEPROM) += i2c-slave-eeprom.o > +obj-$(CONFIG_I2C_SLAVE_MQUEUE) += i2c-slave-mqueue.o > > ccflags-$(CONFIG_I2C_DEBUG_CORE) := -DDEBUG > diff --git a/drivers/i2c/i2c-slave-mqueue.c b/drivers/i2c/i2c-slave-mqueue.c > new file mode 100644 > index 000000000000..c17c4911928f > --- /dev/null > +++ b/drivers/i2c/i2c-slave-mqueue.c > @@ -0,0 +1,215 @@ > +// SPDX-License-Identifier: GPL-2.0 > +// Copyright (c) 2017 - 2018, Intel Corporation. > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#define MQ_MSGBUF_SIZE CONFIG_I2C_SLAVE_MQUEUE_MESSAGE_SIZE > +#define MQ_QUEUE_SIZE CONFIG_I2C_SLAVE_MQUEUE_QUEUE_SIZE > +#define MQ_QUEUE_NEXT(x) (((x) + 1) & (MQ_QUEUE_SIZE - 1)) > + > +struct mq_msg { > + int len; > + u8 *buf; > +}; > + > +struct mq_queue { > + struct bin_attribute bin; > + struct kernfs_node *kn; > + > + spinlock_t lock; /* spinlock for queue index handling */ > + int in; > + int out; > + > + struct mq_msg *curr; > + int truncated; /* drop current if truncated */ > + struct mq_msg queue[MQ_QUEUE_SIZE]; > +}; > + > +static int i2c_slave_mqueue_callback(struct i2c_client *client, > + enum i2c_slave_event event, u8 *val) > +{ > + struct mq_queue *mq = i2c_get_clientdata(client); > + struct mq_msg *msg = mq->curr; > + int ret = 0; > + > + switch (event) { > + case I2C_SLAVE_WRITE_REQUESTED: > + mq->truncated = 0; > + > + msg->len = 1; > + msg->buf[0] = client->addr << 1; > + break; > + > + case I2C_SLAVE_WRITE_RECEIVED: > + if (msg->len < MQ_MSGBUF_SIZE) { > + msg->buf[msg->len++] = *val; > + } else { > + dev_err(&client->dev, "message is truncated!\n"); > + mq->truncated = 1; > + ret = -EINVAL; > + } > + break; > + > + case I2C_SLAVE_STOP: > + if (unlikely(mq->truncated || msg->len < 2)) > + break; > + > + spin_lock(&mq->lock); > + mq->in = MQ_QUEUE_NEXT(mq->in); > + mq->curr = &mq->queue[mq->in]; > + mq->curr->len = 0; > + > + /* Flush the oldest message */ > + if (mq->out == mq->in) > + mq->out = MQ_QUEUE_NEXT(mq->out); > + spin_unlock(&mq->lock); > + > + kernfs_notify(mq->kn); > + break; > + > + default: > + *val = 0xFF; > + break; > + } > + > + return ret; > +} > + > +static ssize_t i2c_slave_mqueue_bin_read(struct file *filp, > + struct kobject *kobj, > + struct bin_attribute *attr, > + char *buf, loff_t pos, size_t count) > +{ > + struct mq_queue *mq; > + struct mq_msg *msg; > + unsigned long flags; > + bool more = false; > + ssize_t ret = 0; > + > + mq = dev_get_drvdata(kobj_to_dev(kobj)); > + > + spin_lock_irqsave(&mq->lock, flags); > + if (mq->out != mq->in) { > + msg = &mq->queue[mq->out]; > + > + if (msg->len <= count) { > + ret = msg->len; > + memcpy(buf, msg->buf, ret); > + } else { > + ret = -EOVERFLOW; /* Drop this HUGE one. */ > + } > + > + mq->out = MQ_QUEUE_NEXT(mq->out); > + if (mq->out != mq->in) > + more = true; > + } > + spin_unlock_irqrestore(&mq->lock, flags); > + > + if (more) > + kernfs_notify(mq->kn); > + > + return ret; > +} > + > +static int i2c_slave_mqueue_probe(struct i2c_client *client, > + const struct i2c_device_id *id) > +{ > + struct device *dev = &client->dev; > + struct mq_queue *mq; > + int ret, i; > + void *buf; > + > + BUILD_BUG_ON(!is_power_of_2(MQ_QUEUE_SIZE)); > + > + mq = devm_kzalloc(dev, sizeof(*mq), GFP_KERNEL); > + if (!mq) > + return -ENOMEM; > + > + buf = devm_kmalloc_array(dev, MQ_QUEUE_SIZE, MQ_MSGBUF_SIZE, > + GFP_KERNEL); > + if (!buf) > + return -ENOMEM; > + > + for (i = 0; i < MQ_QUEUE_SIZE; i++) > + mq->queue[i].buf = buf + i * MQ_MSGBUF_SIZE; > + > + i2c_set_clientdata(client, mq); > + > + spin_lock_init(&mq->lock); > + mq->curr = &mq->queue[0]; > + > + sysfs_bin_attr_init(&mq->bin); > + mq->bin.attr.name = "slave-mqueue"; > + mq->bin.attr.mode = 0400; > + mq->bin.read = i2c_slave_mqueue_bin_read; > + mq->bin.size = MQ_MSGBUF_SIZE * MQ_QUEUE_SIZE; > + > + ret = sysfs_create_bin_file(&dev->kobj, &mq->bin); > + if (ret) > + return ret; > + > + mq->kn = kernfs_find_and_get(dev->kobj.sd, mq->bin.attr.name); > + if (!mq->kn) { > + sysfs_remove_bin_file(&dev->kobj, &mq->bin); > + return -EFAULT; > + } > + > + ret = i2c_slave_register(client, i2c_slave_mqueue_callback); > + if (ret) { > + kernfs_put(mq->kn); > + sysfs_remove_bin_file(&dev->kobj, &mq->bin); > + return ret; > + } > + > + return 0; > +} > + > +static int i2c_slave_mqueue_remove(struct i2c_client *client) > +{ > + struct mq_queue *mq = i2c_get_clientdata(client); > + > + i2c_slave_unregister(client); > + > + kernfs_put(mq->kn); > + sysfs_remove_bin_file(&client->dev.kobj, &mq->bin); > + > + return 0; > +} > + > +static const struct i2c_device_id i2c_slave_mqueue_id[] = { > + { "slave-mqueue", 0 }, > + { /* sentinel */ } > +}; > +MODULE_DEVICE_TABLE(i2c, i2c_slave_mqueue_id); > + > +#ifdef CONFIG_OF > +static const struct of_device_id i2c_slave_mqueue_of_match[] = { > + { > + .compatible = "i2c-slave-mqueue", > + }, > + { /* sentinel */ } > +}; > +MODULE_DEVICE_TABLE(of, i2c_slave_mqueue_of_match); > +#endif > + > +static struct i2c_driver i2c_slave_mqueue_driver = { > + .driver = { > + .name = "i2c-slave-mqueue", > + .of_match_table = of_match_ptr(i2c_slave_mqueue_of_match), > + }, > + .probe = i2c_slave_mqueue_probe, > + .remove = i2c_slave_mqueue_remove, > + .id_table = i2c_slave_mqueue_id, > +}; > +module_i2c_driver(i2c_slave_mqueue_driver); > + > +MODULE_LICENSE("GPL v2"); > +MODULE_AUTHOR("Haiyue Wang "); > +MODULE_DESCRIPTION("I2C slave mode for receiving and queuing messages"); > -- > 2.21.0 > -- With Best Regards, Andy Shevchenko