From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 45A32C4332F for ; Tue, 28 Dec 2021 16:13:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235605AbhL1QNG (ORCPT ); Tue, 28 Dec 2021 11:13:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51298 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235159AbhL1QNF (ORCPT ); Tue, 28 Dec 2021 11:13:05 -0500 Received: from mail-oi1-x22e.google.com (mail-oi1-x22e.google.com [IPv6:2607:f8b0:4864:20::22e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EC391C061574; Tue, 28 Dec 2021 08:13:04 -0800 (PST) Received: by mail-oi1-x22e.google.com with SMTP id j185so30644649oif.8; Tue, 28 Dec 2021 08:13:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=/ukpbqUPRKCiL2g1rOk/6sHlHqKZ+9llkskT8hxgjaM=; b=bKjo0yrekGcOAAM2/35nFFyk6qZibP/haZZnH0BrTPTst/pFSItAJ6E8O8Nakwa4AX Mh8SUO2VNsvbL0zFDClJIeaDTcQWqgZ0FeFvbfPEkoNFF2507q6Tt9nSelRIOMWCArGH NA4fFjCjWiwWFNesOWOSP4qoZk1DLoXD9WonqlyuPBZlH3n9X6JTEoYnkQbf3qP0vxcw 6WUbQ+bq5Ulg/JoRClhrag3ckbYhiUSwOgtZzW/Ig2tkl6wYw5+F6fH5xM0N6moO3A4k Z+ZQPK5XmHDwRjxZNcJcIN/CispeDKhHrZ+BIQC3j3xgt8qMOZvBb7yfH1EEEiWmwiLQ UzmA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:subject:to:cc:references:from:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=/ukpbqUPRKCiL2g1rOk/6sHlHqKZ+9llkskT8hxgjaM=; b=hY6zNCfIJlWCCFNjVPP8OK2JqGPdtQAONO7281t1ov0u0wLiXALfsNuW6jUjwxWTAX XJ99fpQmthi41qSyUMipMsSSxSMhRgR0oLXWxl2lA/ZGqEnycidnRQ4p6xXaxXQGsdzx K0kcOYkccXtPdLmzg6rvYYZJH3Wtwc5Fg47FY5Em4D/YSqRYcjdtpwkvIQKu4YKusneZ +S2R+0hH9vdAt/nK1u+6nFaqmgsDNXA20zzaKh9nZNwupOJU9EwdoKPdpw3lYz5Kf5GV /ELDAhBUT5sRs0QSOft4MOfrtxeJRiSVBTS+lMnj4OdgXQJFXznfdM9tA3GBZBezDZL3 VeYA== X-Gm-Message-State: AOAM531vI3wmfKGggDKagyrpazMEn+izSTZZaopK1e14Dp/x5PumV1f+ +/psOzxX2kDLj5/gC+QDdzmrEE0Fp2w= X-Google-Smtp-Source: ABdhPJwuGPrHR/Q1COPYTA2Jdhc4J0fJX4xcP7k2wQ+Zw7m5kIHodvhNJt5qX83MRxilZkfd0yjIsQ== X-Received: by 2002:a05:6808:181c:: with SMTP id bh28mr15259097oib.31.1640707984047; Tue, 28 Dec 2021 08:13:04 -0800 (PST) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id e26sm3102024oog.46.2021.12.28.08.13.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 28 Dec 2021 08:13:03 -0800 (PST) Sender: Guenter Roeck Subject: Re: [PATCH v2 1/1] hwmon: Add debugfs register access To: Cosmin Tanislav Cc: cosmin.tanislav@analog.com, Jean Delvare , Jonathan Corbet , linux-hwmon@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org References: <20211227224201.508331-1-demonsingur@gmail.com> <20211227224201.508331-2-demonsingur@gmail.com> From: Guenter Roeck Message-ID: Date: Tue, 28 Dec 2021 08:13:01 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20211227224201.508331-2-demonsingur@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/27/21 2:42 PM, Cosmin Tanislav wrote: > From: Cosmin Tanislav > > Similar to IIO, create a device directory inside debugfs > mount point, and create a direct_reg_access file inside > that directory, if debugfs_reg_access callback is defined > inside hwmon_ops. > Patch looks good afaics. I don't want to apply it now (ie for 5.17), though, because it is getting close and we don't have a use case. If you have one in mind, I'd suggest to submit it together with this patch, or we'll have to wait until there is a user. Guenter > Signed-off-by: Cosmin Tanislav > --- > Documentation/hwmon/hwmon-kernel-api.rst | 9 +++ > drivers/hwmon/hwmon.c | 97 ++++++++++++++++++++++++ > include/linux/hwmon.h | 12 +++ > 3 files changed, 118 insertions(+) > > diff --git a/Documentation/hwmon/hwmon-kernel-api.rst b/Documentation/hwmon/hwmon-kernel-api.rst > index c41eb6108103..d568a0bfa5fb 100644 > --- a/Documentation/hwmon/hwmon-kernel-api.rst > +++ b/Documentation/hwmon/hwmon-kernel-api.rst > @@ -136,6 +136,8 @@ The list of hwmon operations is defined as:: > u32 attr, int, long *); > int (*write)(struct device *, enum hwmon_sensor_types type, > u32 attr, int, long); > + int (*reg_access)(struct device *dev, unsigned int reg, > + unsigned int writeval, unsigned int *readval); > }; > > It defines the following operations. > @@ -152,6 +154,13 @@ It defines the following operations. > Pointer to a function for writing a value to the chip. This function is > optional, but must be provided if any writeable attributes exist. > > +* reg_access: > + Pointer to a function for writing or reading a register to the chip. > + This function is optional. > + WARNING: Drivers implementing this function must block any access that > + may cause issues such as power loss, board resets, flash corruption or > + bricking. > + > Each sensor channel is described with struct hwmon_channel_info, which is > defined as follows:: > > diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c > index 3501a3ead4ba..027e5fc33114 100644 > --- a/drivers/hwmon/hwmon.c > +++ b/drivers/hwmon/hwmon.c > @@ -10,6 +10,7 @@ > #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > > #include > +#include > #include > #include > #include > @@ -35,6 +36,9 @@ struct hwmon_device { > struct list_head tzdata; > struct attribute_group group; > const struct attribute_group **groups; > + unsigned int cached_reg_addr; > + char read_buf[20]; > + unsigned int read_buf_len; > }; > > #define to_hwmon_device(d) container_of(d, struct hwmon_device, dev) > @@ -64,6 +68,90 @@ struct hwmon_thermal_data { > struct thermal_zone_device *tzd;/* thermal zone device */ > }; > > +static struct dentry *hwmon_debugfs_dentry; > + > +static ssize_t hwmon_debugfs_read_reg(struct file *file, > + char __user *userbuf, > + size_t count, loff_t *ppos) > +{ > + struct hwmon_device *hwdev = file->private_data; > + unsigned int val; > + int ret; > + > + if (*ppos > 0) > + return simple_read_from_buffer(userbuf, count, ppos, > + hwdev->read_buf, > + hwdev->read_buf_len); > + > + ret = hwdev->chip->ops->reg_access(&hwdev->dev, hwdev->cached_reg_addr, > + 0, &val); > + if (ret) > + return ret; > + > + hwdev->read_buf_len = snprintf(hwdev->read_buf, sizeof(hwdev->read_buf), > + "0x%X\n", val); > + > + return simple_read_from_buffer(userbuf, count, ppos, hwdev->read_buf, > + hwdev->read_buf_len); > +} > + > +static ssize_t hwmon_debugfs_write_reg(struct file *file, > + const char __user *userbuf, > + size_t count, loff_t *ppos) > +{ > + struct hwmon_device *hwdev = file->private_data; > + unsigned int reg, val; > + char buf[80]; > + int ret; > + > + count = min_t(size_t, count, sizeof(buf) - 1); > + if (copy_from_user(buf, userbuf, count)) > + return -EFAULT; > + > + buf[count] = 0; > + > + ret = sscanf(buf, "%i %i", ®, &val); > + > + switch (ret) { > + case 1: > + hwdev->cached_reg_addr = reg; > + break; > + case 2: > + hwdev->cached_reg_addr = reg; > + ret = hwdev->chip->ops->reg_access(&hwdev->dev, reg, val, NULL); > + if (ret) > + return ret; > + break; > + default: > + return -EINVAL; > + } > + > + return count; > +} > + > +static const struct file_operations hwmon_debugfs_reg_fops = { > + .open = simple_open, > + .read = hwmon_debugfs_read_reg, > + .write = hwmon_debugfs_write_reg, > +}; > + > +static void hwmon_device_register_debugfs(struct hwmon_device *hwdev) > +{ > + struct dentry *dir = debugfs_create_dir(dev_name(&hwdev->dev), > + hwmon_debugfs_dentry); > + > + debugfs_create_file("direct_reg_access", 0644, dir, hwdev, > + &hwmon_debugfs_reg_fops); > +} > + > +static void hwmon_device_unregister_debugfs(struct hwmon_device *hwdev) > +{ > + struct dentry *dir = debugfs_lookup(dev_name(&hwdev->dev), > + hwmon_debugfs_dentry); > + > + debugfs_remove_recursive(dir); > +} > + > static ssize_t > name_show(struct device *dev, struct device_attribute *attr, char *buf) > { > @@ -114,6 +202,8 @@ static void hwmon_dev_release(struct device *dev) > { > struct hwmon_device *hwdev = to_hwmon_device(dev); > > + hwmon_device_unregister_debugfs(hwdev); > + > if (hwdev->group.attrs) > hwmon_free_attrs(hwdev->group.attrs); > kfree(hwdev->groups); > @@ -817,6 +907,9 @@ __hwmon_device_register(struct device *dev, const char *name, void *drvdata, > } > } > > + if (chip && chip->ops->reg_access) > + hwmon_device_register_debugfs(hwdev); > + > return hdev; > > free_hwmon: > @@ -1062,12 +1155,16 @@ static int __init hwmon_init(void) > pr_err("couldn't register hwmon sysfs class\n"); > return err; > } > + > + hwmon_debugfs_dentry = debugfs_create_dir("hwmon", NULL); > + > return 0; > } > > static void __exit hwmon_exit(void) > { > class_unregister(&hwmon_class); > + debugfs_remove(hwmon_debugfs_dentry); > } > > subsys_initcall(hwmon_init); > diff --git a/include/linux/hwmon.h b/include/linux/hwmon.h > index fad1f1df26df..587fb2931ac1 100644 > --- a/include/linux/hwmon.h > +++ b/include/linux/hwmon.h > @@ -390,6 +390,16 @@ enum hwmon_intrusion_attributes { > * Channel number > * @val: Value to write > * The function returns 0 on success or a negative error number. > + * @reg_access: > + * Callback to read or write register values. > + * Parameters are: > + * @dev: Pointer to hardware monitoring device > + * @reg: Register address to read or write > + * @writeval: > + * Value to write to register. 0 when reading. > + * @readval: > + * Pointer to value read from register. NULL when writing. > + * The function returns 0 on success or a negative error number. > */ > struct hwmon_ops { > umode_t (*is_visible)(const void *drvdata, enum hwmon_sensor_types type, > @@ -400,6 +410,8 @@ struct hwmon_ops { > u32 attr, int channel, const char **str); > int (*write)(struct device *dev, enum hwmon_sensor_types type, > u32 attr, int channel, long val); > + int (*reg_access)(struct device *dev, unsigned int reg, > + unsigned int writeval, unsigned int *readval); > }; > > /** >