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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1j5BR1-0005xx-T1; Fri, 21 Feb 2020 16:45:51 +0000 Received: from bhuna.collabora.co.uk ([46.235.227.227]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1j5BQy-0005xc-82 for linux-i3c@lists.infradead.org; Fri, 21 Feb 2020 16:45:50 +0000 Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:5cf4:84a1:2763:fe0d]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: bbrezillon) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id 404FD294A83; Fri, 21 Feb 2020 16:45:46 +0000 (GMT) Date: Fri, 21 Feb 2020 17:45:43 +0100 From: Boris Brezillon To: Greg KH Subject: Re: [PATCH v3 3/5] i3c: master: add i3c_for_each_dev helper Message-ID: <20200221174543.303f6ecd@collabora.com> In-Reply-To: <20200221174428.77696ab6@collabora.com> References: <868e5b37fd817b65e6953ed7279f5063e5fc06c5.1582069402.git.vitor.soares@synopsys.com> <20200219073548.GA2728338@kroah.com> <20200221115229.GA116368@kroah.com> <20200221135911.1300170b@collabora.com> <20200221174428.77696ab6@collabora.com> Organization: Collabora X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200221_084548_559517_0F1D121F X-CRM114-Status: GOOD ( 42.74 ) X-BeenThere: linux-i3c@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux I3C List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jose Abreu , Joao Pinto , "arnd@arndb.de" , "corbet@lwn.net" , "wsa@the-dreams.de" , "linux-kernel@vger.kernel.org" , Vitor Soares , "broonie@kernel.org" , "linux-i3c@lists.infradead.org" , "bbrezillon@kernel.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-i3c" Errors-To: linux-i3c-bounces+linux-i3c=archiver.kernel.org@lists.infradead.org On Fri, 21 Feb 2020 17:44:28 +0100 Boris Brezillon wrote: > On Fri, 21 Feb 2020 13:59:11 +0100 > Boris Brezillon wrote: > > > On Fri, 21 Feb 2020 12:52:29 +0100 > > Greg KH wrote: > > > > > On Fri, Feb 21, 2020 at 11:47:22AM +0000, Vitor Soares wrote: > > > > Hi Greg, > > > > > > > > From: Greg KH > > > > Date: Wed, Feb 19, 2020 at 07:35:48 > > > > > > > > > On Wed, Feb 19, 2020 at 01:20:41AM +0100, Vitor Soares wrote: > > > > > > Introduce i3c_for_each_dev(), an i3c device iterator for use by i3cdev. > > > > > > > > > > > > Signed-off-by: Vitor Soares > > > > > > --- > > > > > > drivers/i3c/internals.h | 1 + > > > > > > drivers/i3c/master.c | 12 ++++++++++++ > > > > > > 2 files changed, 13 insertions(+) > > > > > > > > > > > > diff --git a/drivers/i3c/internals.h b/drivers/i3c/internals.h > > > > > > index bc062e8..a6deedf 100644 > > > > > > --- a/drivers/i3c/internals.h > > > > > > +++ b/drivers/i3c/internals.h > > > > > > @@ -24,4 +24,5 @@ int i3c_dev_enable_ibi_locked(struct i3c_dev_desc *dev); > > > > > > int i3c_dev_request_ibi_locked(struct i3c_dev_desc *dev, > > > > > > const struct i3c_ibi_setup *req); > > > > > > void i3c_dev_free_ibi_locked(struct i3c_dev_desc *dev); > > > > > > +int i3c_for_each_dev(void *data, int (*fn)(struct device *, void *)); > > > > > > #endif /* I3C_INTERNAL_H */ > > > > > > diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c > > > > > > index 21c4372..8e22da2 100644 > > > > > > --- a/drivers/i3c/master.c > > > > > > +++ b/drivers/i3c/master.c > > > > > > @@ -2640,6 +2640,18 @@ void i3c_dev_free_ibi_locked(struct i3c_dev_desc *dev) > > > > > > dev->ibi = NULL; > > > > > > } > > > > > > > > > > > > +int i3c_for_each_dev(void *data, int (*fn)(struct device *, void *)) > > > > > > +{ > > > > > > + int res; > > > > > > + > > > > > > + mutex_lock(&i3c_core_lock); > > > > > > + res = bus_for_each_dev(&i3c_bus_type, NULL, data, fn); > > > > > > + mutex_unlock(&i3c_core_lock); > > > > > > > > > > Ick, why the lock? Are you _sure_ you need that? The core should > > > > > handle any list locking issues here, right? > > > > > > > > I want to make sure that no new devices (eg: Hot-Join capable device) are > > > > added during this iteration and after this call, each new device will > > > > release a bus notification. > > > > > > > > > > > > > > I don't see bus-specific-locks around other subsystem functions that do > > > > > this (like usb_for_each_dev). > > > > > > > > I based in I2C use case. > > > > > > Check to see if this is really needed, for some reason I doubt it... > > > > Can we please try the spidev approach before fixing those problems. None > > of that would be needed if we declare the i3cdev driver as a regular > > i3c_device_driver and let user space bind devices it wants to expose > > through the sysfs interface. As I said earlier, we even have all the > > pieces we need to automate that using a udev rule, and the resulting > > patchset would be 'less invasive'/simpler for pretty much the same > > result. > > So, I went ahead and implemented it the way I suggest. The diffstat is > not representative here (though it's still in favor of this new version) > since I also changed the way we expose/handle SDR transfers. What's > most important IMO is the fact that > > * we no longer need to access the internal I3C API > * we no longer need to care about transitions between i3cdev and > other drivers (the core guarantees that a device is always bound to at > most one driver) > * the registration/unregistration procedure is simplified Forgot to mention that * Patch 1-3 are no longer required > > Not all problems have been addressed (we still need to put a limit on > the number of xfers and the max size per transfer we allow, and > probably plenty of other things pointed by Greg, Arnd and others), but > I'd really like to start from there for the next version. > > --->8--- > From a344e3c51db4e414e4ec6007c001c32afa954a82 Mon Sep 17 00:00:00 2001 > From: Vitor Soares > Date: Wed, 19 Feb 2020 01:20:42 +0100 > Subject: [PATCH] i3c: add i3cdev module to expose i3c dev in /dev > > This patch adds user mode support to I3C SDR transfers. > > The module is based on spidev with the follow features: > - Dynamically allocate the char device Major number. > - Expose SDR (Single Data Rate) transfers > > Signed-off-by: Vitor Soares > --- > drivers/i3c/Kconfig | 15 ++ > drivers/i3c/Makefile | 1 + > drivers/i3c/i3cdev.c | 324 ++++++++++++++++++++++++++++++++ > include/uapi/linux/i3c/i3cdev.h | 38 ++++ > 4 files changed, 378 insertions(+) > create mode 100644 drivers/i3c/i3cdev.c > create mode 100644 include/uapi/linux/i3c/i3cdev.h > > diff --git a/drivers/i3c/Kconfig b/drivers/i3c/Kconfig > index 30a441506f61..01642768ab5f 100644 > --- a/drivers/i3c/Kconfig > +++ b/drivers/i3c/Kconfig > @@ -20,5 +20,20 @@ menuconfig I3C > will be called i3c. > > if I3C > + > +config I3CDEV > + tristate "I3C device interface" > + depends on I3C > + help > + Say Y here to use i3c-* device files, usually found in the /dev > + directory on your system. They make it possible to have user-space > + programs use the I3C devices. > + > + This support is also available as a module. If so, the module > + will be called i3cdev. > + > + Note that this application programming interface is EXPERIMENTAL > + and hence SUBJECT TO CHANGE WITHOUT NOTICE while it stabilizes. > + > source "drivers/i3c/master/Kconfig" > endif # I3C > diff --git a/drivers/i3c/Makefile b/drivers/i3c/Makefile > index 11982efbc6d9..606d422841b2 100644 > --- a/drivers/i3c/Makefile > +++ b/drivers/i3c/Makefile > @@ -1,4 +1,5 @@ > # SPDX-License-Identifier: GPL-2.0 > i3c-y := device.o master.o > obj-$(CONFIG_I3C) += i3c.o > +obj-$(CONFIG_I3CDEV) += i3cdev.o > obj-$(CONFIG_I3C) += master/ > diff --git a/drivers/i3c/i3cdev.c b/drivers/i3c/i3cdev.c > new file mode 100644 > index 000000000000..2b408a446ab6 > --- /dev/null > +++ b/drivers/i3c/i3cdev.c > @@ -0,0 +1,324 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (c) 2020 Synopsys, Inc. and/or its affiliates. > + * > + * Author: Vitor Soares > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#include > + > +#define MAX_I3CDEV_DEVS (MINORMASK + 1) > + > +struct i3cdev_data { > + struct i3c_device *i3c; > + struct device *dev; > + struct cdev cdev; > + dev_t devt; > +}; > + > +static DEFINE_IDA(i3cdev_ida); > +static dev_t i3cdev_first_chrdev; > + > +static ssize_t > +i3cdev_read(struct file *file, char __user *buf, size_t count, loff_t *f_pos) > +{ > + struct i3cdev_data *i3cdev = file->private_data; > + struct i3c_device *i3c = i3cdev->i3c; > + struct i3c_priv_xfer xfers = { > + .rnw = true, > + .len = count, > + }; > + char *tmp; > + int ret; > + > + tmp = kzalloc(count, GFP_KERNEL); > + if (!tmp) > + return -ENOMEM; > + > + xfers.data.in = tmp; > + > + dev_dbg(i3cdev->dev, "Reading %zu bytes.\n", count); > + > + ret = i3c_device_do_priv_xfers(i3c, &xfers, 1); > + if (!ret) > + ret = copy_to_user(buf, tmp, xfers.len) ? -EFAULT : xfers.len; > + > + kfree(tmp); > + return ret; > +} > + > +static ssize_t > +i3cdev_write(struct file *file, const char __user *buf, size_t count, > + loff_t *f_pos) > +{ > + struct i3cdev_data *i3cdev = file->private_data; > + struct i3c_device *i3c = i3cdev->i3c; > + struct i3c_priv_xfer xfers = { > + .rnw = false, > + .len = count, > + }; > + char *tmp; > + int ret; > + > + tmp = memdup_user(buf, count); > + if (IS_ERR(tmp)) > + return PTR_ERR(tmp); > + > + xfers.data.out = tmp; > + > + dev_dbg(i3cdev->dev, "Writing %zu bytes.\n", count); > + > + ret = i3c_device_do_priv_xfers(i3c, &xfers, 1); > + kfree(tmp); > + > + return !ret ? count : ret; > +} > + > +static int > +i3cdev_ioctl_priv_xfers(struct i3c_device *i3c, > + struct i3cdev_priv_xfers __user *uxfers) > +{ > + struct i3cdev_priv_xfers xfers; > + struct i3cdev_priv_xfer *uxfer_array; > + struct i3c_priv_xfer *xfer_array; > + unsigned int i; > + int ret; > + > + if (copy_from_user(&xfers, uxfers, sizeof(xfers))) > + return -EFAULT; > + > + /* TODO: Add a limit for xfers.nxfers. */ > + uxfer_array = memdup_user(u64_to_user_ptr(xfers.xfers), > + xfers.nxfers * sizeof(*uxfer_array)); > + if (!uxfer_array) > + return -ENOMEM; > + > + xfer_array = kmalloc_array(xfers.nxfers, sizeof(*xfer_array), > + GFP_KERNEL); > + if (!xfer_array) { > + ret = -ENOMEM; > + goto out_free_uxfer_array; > + } > + > + /* TODO Add a limit for max in/out size. */ > + for (i = 0; i < xfers.nxfers; i++) { > + void __user *udata = u64_to_user_ptr(uxfer_array[i].data); > + void *data; > + > + xfer_array[i].rnw = uxfer_array[i].rnw; > + xfer_array[i].len = uxfer_array[i].len; > + > + if (!xfer_array[i].rnw) { > + data = memdup_user(udata, xfer_array[i].len); > + } else { > + data = kzalloc(xfer_array[i].len, GFP_KERNEL); > + if (data) > + data = ERR_PTR(-ENOMEM); > + } > + > + if (IS_ERR(data)) { > + ret = PTR_ERR(xfer_array[i].data.in); > + goto out_free_xfer_array; > + } > + > + xfer_array[i].data.in = data; > + } > + > + ret = i3c_device_do_priv_xfers(i3c, xfer_array, xfers.nxfers); > + > + if (!ret) { > + for (i = 0; i < xfers.nxfers; i++) { > + void __user *udata = u64_to_user_ptr(uxfer_array[i].data); > + void *data = xfer_array[i].data.in; > + > + if (!xfer_array[i].rnw) > + continue; > + > + if (copy_to_user(udata, data, xfer_array[i].len)) { > + ret = -EFAULT; > + goto out_free_xfer_array; > + } > + } > + } > + > +out_free_xfer_array: > + for (i = 0; i < xfers.nxfers; i++) > + kfree(xfer_array[i].data.in); > + > + kfree(xfer_array); > + > +out_free_uxfer_array: > + kfree(uxfer_array); > + return ret; > +} > + > +static long > +i3cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg) > +{ > + struct i3cdev_data *i3cdev = file->private_data; > + void __user *udata = (void __user *)arg; > + int ret = -EACCES; > + > + dev_dbg(i3cdev->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n", cmd, arg); > + > + switch (cmd) { > + case I3CDEV_PRIV_XFER: > + ret = i3cdev_ioctl_priv_xfers(i3cdev->i3c, udata); > + break; > + default: > + return -ENOTTY; > + } > + > + return ret; > +} > + > +static int i3cdev_open(struct inode *inode, struct file *file) > +{ > + struct i3cdev_data *i3cdev = container_of(inode->i_cdev, > + struct i3cdev_data, > + cdev); > + file->private_data = i3cdev; > + > + return 0; > +} > + > +static int i3cdev_release(struct inode *inode, struct file *file) > +{ > + file->private_data = NULL; > + > + return 0; > +} > + > +static const struct file_operations i3cdev_fops = { > + .owner = THIS_MODULE, > + .read = i3cdev_read, > + .write = i3cdev_write, > + .unlocked_ioctl = i3cdev_ioctl, > + .compat_ioctl = compat_ptr_ioctl, > + .open = i3cdev_open, > + .release = i3cdev_release, > +}; > + > +/* ------------------------------------------------------------------------- */ > + > +static struct class *i3cdev_class; > + > +static int i3cdev_probe(struct i3c_device *i3c) > +{ > + struct device *dev = i3cdev_to_dev(i3c); > + struct i3cdev_data *i3cdev; > + int ret; > + int id; > + > + i3cdev = devm_kzalloc(dev, sizeof(*i3cdev), GFP_KERNEL); > + if (!i3cdev) > + return -ENOMEM; > + > + ret = ida_simple_get(&i3cdev_ida, 0, MAX_I3CDEV_DEVS, GFP_KERNEL); > + if (ret < 0) { > + dev_err(dev, "no minor number available!\n"); > + return ret; > + } > + > + i3cdev->i3c = i3c; > + i3cdev->devt = MKDEV(MAJOR(i3cdev_first_chrdev), > + MINOR(i3cdev_first_chrdev) + ret); > + i3cdev_set_drvdata(i3c, i3cdev); > + cdev_init(&i3cdev->cdev, &i3cdev_fops); > + i3cdev->cdev.owner = THIS_MODULE; > + ret = cdev_add(&i3cdev->cdev, i3cdev->devt, 1); > + if (ret) > + goto error_free_id; > + > + i3cdev->dev = device_create(i3cdev_class, dev, i3cdev->devt, > + NULL, "i3cdev%d", id); > + if (IS_ERR(i3cdev->dev)) { > + ret = PTR_ERR(i3cdev->dev); > + goto error_free_cdev; > + } > + > + return 0; > + > +error_free_cdev: > + cdev_del(&i3cdev->cdev); > +error_free_id: > + ida_free(&i3cdev_ida, > + MINOR(i3cdev->devt) - MINOR(i3cdev_first_chrdev)); > + return ret; > +} > + > +static int i3cdev_remove(struct i3c_device *i3c) > +{ > + struct i3cdev_data *i3cdev; > + > + i3cdev = i3cdev_get_drvdata(i3c); > + > + device_destroy(i3cdev_class, i3cdev->devt); > + cdev_del(&i3cdev->cdev); > + ida_simple_remove(&i3cdev_ida, > + MINOR(i3cdev->devt) - MINOR(i3cdev_first_chrdev)); > + > + return 0; > +} > + > +static const struct i3c_device_id i3cdev_ids[] = { > + { /* Sentinel */ }, > +}; > + > +static struct i3c_driver i3cdev_driver = { > + .probe = i3cdev_probe, > + .remove = i3cdev_remove, > + .id_table = i3cdev_ids, > +}; > + > +static int __init i3cdev_init(void) > +{ > + int ret; > + > + ret = alloc_chrdev_region(&i3cdev_first_chrdev, 0, MAX_I3CDEV_DEVS, > + "i3cdev"); > + if (ret) > + return ret; > + > + i3cdev_class = class_create(THIS_MODULE, "i3cdev"); > + if (IS_ERR(i3cdev_class)) > + goto err_unreg_chrdev_region; > + > + ret = i3c_driver_register(&i3cdev_driver); > + if (ret) > + goto err_destroy_class; > + > + return 0; > + > +err_destroy_class: > + class_destroy(i3cdev_class); > +err_unreg_chrdev_region: > + unregister_chrdev_region(i3cdev_first_chrdev, MAX_I3CDEV_DEVS); > + return ret; > +} > +module_init(i3cdev_init); > + > +static void __exit i3cdev_exit(void) > +{ > + i3c_driver_unregister(&i3cdev_driver); > + class_destroy(i3cdev_class); > + unregister_chrdev_region(i3cdev_first_chrdev, MAX_I3CDEV_DEVS); > +} > +module_exit(i3cdev_exit); > + > +MODULE_AUTHOR("Vitor Soares "); > +MODULE_DESCRIPTION("I3C /dev entries driver"); > +MODULE_LICENSE("GPL"); > diff --git a/include/uapi/linux/i3c/i3cdev.h b/include/uapi/linux/i3c/i3cdev.h > new file mode 100644 > index 000000000000..305dc029ca2d > --- /dev/null > +++ b/include/uapi/linux/i3c/i3cdev.h > @@ -0,0 +1,38 @@ > +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ > +/* > + * Copyright (c) 2020 Synopsys, Inc. and/or its affiliates. > + * > + * Author: Vitor Soares > + */ > + > +#ifndef _UAPI_I3C_DEV_H_ > +#define _UAPI_I3C_DEV_H_ > + > +#include > +#include > + > +/* IOCTL commands */ > +#define I3C_DEV_IOC_MAGIC 0x07 > + > +/** > + * struct i3c_ioc_priv_xfer - I3C SDR ioctl private transfer > + * @data: Holds pointer to userspace buffer with transmit data. > + * @len: Length of data buffer buffers, in bytes. > + * @rnw: encodes the transfer direction. true for a read, false for a write > + */ > +struct i3cdev_priv_xfer { > + __u64 data; > + __u16 len; > + __u8 rnw; > + __u8 pad[5]; > +}; > + > +struct i3cdev_priv_xfers { > + __u64 nxfers; > + __u64 xfers; > +}; > + > +#define I3CDEV_PRIV_XFER \ > + _IOWR(I3C_DEV_IOC_MAGIC, 0, struct i3cdev_priv_xfers) > + > +#endif _______________________________________________ linux-i3c mailing list linux-i3c@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-i3c