From nobody Tue Feb 10 04:23:42 2026 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 471C5C6FD1D for ; Mon, 20 Mar 2023 22:06:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229663AbjCTWGY (ORCPT ); Mon, 20 Mar 2023 18:06:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55150 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229455AbjCTWGV (ORCPT ); Mon, 20 Mar 2023 18:06:21 -0400 Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 196AC7EE8 for ; Mon, 20 Mar 2023 15:06:16 -0700 (PDT) Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 32KLCj8e012156; Mon, 20 Mar 2023 22:06:09 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding; s=pp1; bh=AV88f+76ahwOXTELtVaHbKx8Syz2qs3ENASHWyGOxMc=; b=gEHqOMhqLFy4irGTy2FU1yD4MqKAsn3+uD512vEookc22Tvj3vg7pN12NK1mirLDbvzi IJFeuvbNQlHnQURd5V6VvrYAPj5kzB6T6zlvE2nakWuwOW7ROUf6ES1BJekxXnbHfkQw t7rlpjLL+qfMpNiWqact06uLD81AsjZArYuZvLTO+qxd8yOFyIPu6RfoNhAeX3IHbHS5 AmJ3bTDmMON9tO132O6WdtbcxaeOg5yY7vpfxvp7wrefJL5rhCQdHO2zIccxXkSh3bBg dtobuY9j+ghvzkS3f5SpUjYEgiOMjzoDQv5u76u5xU7svWTgD2J8VmkRMn0rmdimFNxs pw== Received: from ppma04wdc.us.ibm.com (1a.90.2fa9.ip4.static.sl-reverse.com [169.47.144.26]) by mx0b-001b2d01.pphosted.com (PPS) with ESMTPS id 3pest030tw-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 20 Mar 2023 22:06:09 +0000 Received: from pps.filterd (ppma04wdc.us.ibm.com [127.0.0.1]) by ppma04wdc.us.ibm.com (8.17.1.19/8.17.1.19) with ESMTP id 32KJrSKQ022214; Mon, 20 Mar 2023 22:06:08 GMT Received: from smtprelay02.wdc07v.mail.ibm.com ([9.208.129.120]) by ppma04wdc.us.ibm.com (PPS) with ESMTPS id 3pd4x6y5se-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 20 Mar 2023 22:06:08 +0000 Received: from smtpav01.dal12v.mail.ibm.com (smtpav01.dal12v.mail.ibm.com [10.241.53.100]) by smtprelay02.wdc07v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 32KM67Lu24117836 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 20 Mar 2023 22:06:07 GMT Received: from smtpav01.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 81AA258058; Mon, 20 Mar 2023 22:06:07 +0000 (GMT) Received: from smtpav01.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CE46358057; Mon, 20 Mar 2023 22:06:06 +0000 (GMT) Received: from slate16.aus.stglabs.ibm.com (unknown [9.160.23.218]) by smtpav01.dal12v.mail.ibm.com (Postfix) with ESMTP; Mon, 20 Mar 2023 22:06:06 +0000 (GMT) From: Eddie James To: linux-kernel@vger.kernel.org Cc: arnd@arndb.de, gregkh@linuxfoundation.org, jdelvare@suse.de, Eddie James Subject: [PATCH] eeprom: ee1004: Enable devices on multiple busses Date: Mon, 20 Mar 2023 17:06:03 -0500 Message-Id: <20230320220603.442782-1-eajames@linux.ibm.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-GUID: PhwiY0B_-nwRB61Exccr_vrCcXnxLiBb X-Proofpoint-ORIG-GUID: PhwiY0B_-nwRB61Exccr_vrCcXnxLiBb X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-03-20_16,2023-03-20_02,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 phishscore=0 spamscore=0 mlxlogscore=999 impostorscore=0 bulkscore=0 clxscore=1011 priorityscore=1501 mlxscore=0 adultscore=0 lowpriorityscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2303150002 definitions=main-2303200187 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The driver previously prevented probing devices on more than one bus due to locking constraints with the special page addresses. This constraint can be removed by allocating a reference-counted bus structure containing the lock, rather than using global variables. Signed-off-by: Eddie James --- drivers/misc/eeprom/ee1004.c | 175 +++++++++++++++++++++-------------- 1 file changed, 106 insertions(+), 69 deletions(-) diff --git a/drivers/misc/eeprom/ee1004.c b/drivers/misc/eeprom/ee1004.c index c8c6deb7ed89..950813821087 100644 --- a/drivers/misc/eeprom/ee1004.c +++ b/drivers/misc/eeprom/ee1004.c @@ -9,12 +9,15 @@ * Copyright (C) 2008 Wolfram Sang, Pengutronix */ =20 +#include #include #include #include +#include #include #include #include +#include =20 /* * DDR4 memory modules use special EEPROMs following the Jedec EE1004 @@ -31,20 +34,24 @@ * over performance. */ =20 -#define EE1004_ADDR_SET_PAGE 0x36 +#define EE1004_ADDR_SET_PAGE0 0x36 +#define EE1004_ADDR_SET_PAGE1 0x37 #define EE1004_NUM_PAGES 2 #define EE1004_PAGE_SIZE 256 #define EE1004_PAGE_SHIFT 8 #define EE1004_EEPROM_SIZE (EE1004_PAGE_SIZE * EE1004_NUM_PAGES) =20 -/* - * Mutex protects ee1004_set_page and ee1004_dev_count, and must be held - * from page selection to end of read. - */ -static DEFINE_MUTEX(ee1004_bus_lock); -static struct i2c_client *ee1004_set_page[EE1004_NUM_PAGES]; -static unsigned int ee1004_dev_count; -static int ee1004_current_page; +struct ee1004_bus { + struct kref kref; + struct list_head list; + struct mutex lock; + struct i2c_adapter *adapter; + struct i2c_client *set_page_clients[EE1004_NUM_PAGES]; + int page; +}; + +static LIST_HEAD(ee1004_busses); +static DEFINE_MUTEX(ee1004_busses_lock); =20 static const struct i2c_device_id ee1004_ids[] =3D { { "ee1004", 0 }, @@ -54,11 +61,11 @@ MODULE_DEVICE_TABLE(i2c, ee1004_ids); =20 /*------------------------------------------------------------------------= -*/ =20 -static int ee1004_get_current_page(void) +static int ee1004_get_current_page(struct ee1004_bus *bus) { int err; =20 - err =3D i2c_smbus_read_byte(ee1004_set_page[0]); + err =3D i2c_smbus_read_byte(bus->set_page_clients[0]); if (err =3D=3D -ENXIO) { /* Nack means page 1 is selected */ return 1; @@ -72,33 +79,30 @@ static int ee1004_get_current_page(void) return 0; } =20 -static int ee1004_set_current_page(struct device *dev, int page) +static int ee1004_set_current_page(struct ee1004_bus *bus, int page) { int ret; =20 - if (page =3D=3D ee1004_current_page) + if (page =3D=3D bus->page) return 0; =20 /* Data is ignored */ - ret =3D i2c_smbus_write_byte(ee1004_set_page[page], 0x00); + ret =3D i2c_smbus_write_byte(bus->set_page_clients[page], 0x00); + /* * Don't give up just yet. Some memory modules will select the page * but not ack the command. Check which page is selected now. */ - if (ret =3D=3D -ENXIO && ee1004_get_current_page() =3D=3D page) + if (ret =3D=3D -ENXIO && ee1004_get_current_page(bus) =3D=3D page) ret =3D 0; - if (ret < 0) { - dev_err(dev, "Failed to select page %d (%d)\n", page, ret); + if (ret < 0) return ret; - } - - dev_dbg(dev, "Selected page %d\n", page); - ee1004_current_page =3D page; =20 + bus->page =3D page; return 0; } =20 -static ssize_t ee1004_eeprom_read(struct i2c_client *client, char *buf, +static ssize_t ee1004_eeprom_read(struct i2c_client *client, struct ee1004= _bus *bus, char *buf, unsigned int offset, size_t count) { int status, page; @@ -106,9 +110,11 @@ static ssize_t ee1004_eeprom_read(struct i2c_client *c= lient, char *buf, page =3D offset >> EE1004_PAGE_SHIFT; offset &=3D (1 << EE1004_PAGE_SHIFT) - 1; =20 - status =3D ee1004_set_current_page(&client->dev, page); - if (status) + status =3D ee1004_set_current_page(bus, page); + if (status) { + dev_err(&client->dev, "Failed to select page %d (%d)\n", page, status); return status; + } =20 /* Can't cross page boundaries */ if (offset + count > EE1004_PAGE_SIZE) @@ -125,6 +131,7 @@ static ssize_t eeprom_read(struct file *filp, struct ko= bject *kobj, char *buf, loff_t off, size_t count) { struct i2c_client *client =3D kobj_to_i2c_client(kobj); + struct ee1004_bus *bus =3D i2c_get_clientdata(client); size_t requested =3D count; int ret =3D 0; =20 @@ -132,10 +139,10 @@ static ssize_t eeprom_read(struct file *filp, struct = kobject *kobj, * Read data from chip, protecting against concurrent access to * other EE1004 SPD EEPROMs on the same adapter. */ - mutex_lock(&ee1004_bus_lock); + mutex_lock(&bus->lock); =20 while (count) { - ret =3D ee1004_eeprom_read(client, buf, off, count); + ret =3D ee1004_eeprom_read(client, bus, buf, off, count); if (ret < 0) goto out; =20 @@ -144,7 +151,7 @@ static ssize_t eeprom_read(struct file *filp, struct ko= bject *kobj, count -=3D ret; } out: - mutex_unlock(&ee1004_bus_lock); + mutex_unlock(&bus->lock); =20 return ret < 0 ? ret : requested; } @@ -158,18 +165,56 @@ static struct bin_attribute *ee1004_attrs[] =3D { =20 BIN_ATTRIBUTE_GROUPS(ee1004); =20 -static void ee1004_cleanup(int idx) +static void ee1004_bus_unregister(struct ee1004_bus *bus) { - if (--ee1004_dev_count =3D=3D 0) - while (--idx >=3D 0) { - i2c_unregister_device(ee1004_set_page[idx]); - ee1004_set_page[idx] =3D NULL; - } + i2c_unregister_device(bus->set_page_clients[1]); + i2c_unregister_device(bus->set_page_clients[0]); +} + +static void ee1004_bus_release(struct kref *kref) +{ + struct ee1004_bus *bus =3D container_of(kref, struct ee1004_bus, kref); + + ee1004_bus_unregister(bus); + + mutex_lock(&ee1004_busses_lock); + list_del(&bus->list); + mutex_unlock(&ee1004_busses_lock); + + kfree(bus); +} + +static int ee1004_bus_initialize(struct ee1004_bus *bus, struct i2c_adapte= r *adapter) +{ + bus->set_page_clients[0] =3D i2c_new_dummy_device(adapter, EE1004_ADDR_SE= T_PAGE0); + if (IS_ERR(bus->set_page_clients[0])) + return PTR_ERR(bus->set_page_clients[0]); + + bus->set_page_clients[1] =3D i2c_new_dummy_device(adapter, EE1004_ADDR_SE= T_PAGE1); + if (IS_ERR(bus->set_page_clients[1])) { + i2c_unregister_device(bus->set_page_clients[0]); + return PTR_ERR(bus->set_page_clients[1]); + } + + bus->page =3D ee1004_get_current_page(bus); + if (bus->page < 0) { + ee1004_bus_unregister(bus); + return bus->page; + } + + kref_init(&bus->kref); + list_add(&bus->list, &ee1004_busses); + mutex_init(&bus->lock); + bus->adapter =3D adapter; + + return 0; } =20 static int ee1004_probe(struct i2c_client *client) { - int err, cnr =3D 0; + struct ee1004_bus *bus; + bool found =3D false; + int rc =3D 0; =20 /* Make sure we can operate on this adapter */ if (!i2c_check_functionality(client->adapter, @@ -178,53 +223,45 @@ static int ee1004_probe(struct i2c_client *client) I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_READ_BYTE_DATA)) return -EPFNOSUPPORT; =20 - /* Use 2 dummy devices for page select command */ - mutex_lock(&ee1004_bus_lock); - if (++ee1004_dev_count =3D=3D 1) { - for (cnr =3D 0; cnr < EE1004_NUM_PAGES; cnr++) { - struct i2c_client *cl; - - cl =3D i2c_new_dummy_device(client->adapter, EE1004_ADDR_SET_PAGE + cnr= ); - if (IS_ERR(cl)) { - err =3D PTR_ERR(cl); - goto err_clients; - } - ee1004_set_page[cnr] =3D cl; + mutex_lock(&ee1004_busses_lock); + list_for_each_entry(bus, &ee1004_busses, list) { + if (bus->adapter =3D=3D client->adapter) { + kref_get(&bus->kref); + found =3D true; + break; + } + } + + if (!found) { + bus =3D kzalloc(sizeof(*bus), GFP_KERNEL); + if (!bus) { + rc =3D -ENOMEM; + goto unlock; } =20 - /* Remember current page to avoid unneeded page select */ - err =3D ee1004_get_current_page(); - if (err < 0) - goto err_clients; - dev_dbg(&client->dev, "Currently selected page: %d\n", err); - ee1004_current_page =3D err; - } else if (client->adapter !=3D ee1004_set_page[0]->adapter) { - dev_err(&client->dev, - "Driver only supports devices on a single I2C bus\n"); - err =3D -EOPNOTSUPP; - goto err_clients; + rc =3D ee1004_bus_initialize(bus, client->adapter); + if (rc) { + kfree(bus); + goto unlock; + } } - mutex_unlock(&ee1004_bus_lock); + + i2c_set_clientdata(client, bus); =20 dev_info(&client->dev, "%u byte EE1004-compliant SPD EEPROM, read-only\n", EE1004_EEPROM_SIZE); =20 - return 0; - - err_clients: - ee1004_cleanup(cnr); - mutex_unlock(&ee1004_bus_lock); - - return err; +unlock: + mutex_unlock(&ee1004_busses_lock); + return rc; } =20 static void ee1004_remove(struct i2c_client *client) { - /* Remove page select clients if this is the last device */ - mutex_lock(&ee1004_bus_lock); - ee1004_cleanup(EE1004_NUM_PAGES); - mutex_unlock(&ee1004_bus_lock); + struct ee1004_bus *bus =3D i2c_get_clientdata(client); + + kref_put(&bus->kref, ee1004_bus_release); } =20 /*------------------------------------------------------------------------= -*/ --=20 2.31.1