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Tue, 21 Mar 2023 15:16:49 +0000 (GMT) From: Eddie James To: linux-kernel@vger.kernel.org Cc: linux-aspeed@lists.ozlabs.org, devicetree@vger.kernel.org, andrew@aj.id.au, joel@jms.id.au, krzysztof.kozlowski+dt@linaro.org, robh+dt@kernel.org, arnd@arndb.de, gregkh@linuxfoundation.org, Eddie James Subject: [PATCH v2 1/4] eeprom: ee1004: Enable devices on multiple busses Date: Tue, 21 Mar 2023 10:16:39 -0500 Message-Id: <20230321151642.461618-2-eajames@linux.ibm.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20230321151642.461618-1-eajames@linux.ibm.com> References: <20230321151642.461618-1-eajames@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: zLSjT5HD4Kbb_31fCD-c9IZnScW7idoq X-Proofpoint-ORIG-GUID: zLSjT5HD4Kbb_31fCD-c9IZnScW7idoq 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=2023-03-21_11,2023-03-21_01,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 malwarescore=0 adultscore=0 phishscore=0 lowpriorityscore=0 suspectscore=0 mlxscore=0 spamscore=0 bulkscore=0 priorityscore=1501 mlxlogscore=999 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2303150002 definitions=main-2303210118 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 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-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1760993349947209110?= X-GMAIL-MSGID: =?utf-8?q?1760993349947209110?= 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 */ +#include #include #include #include +#include #include #include #include +#include /* * DDR4 memory modules use special EEPROMs following the Jedec EE1004 @@ -31,20 +34,24 @@ * over performance. */ -#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) -/* - * 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); static const struct i2c_device_id ee1004_ids[] = { { "ee1004", 0 }, @@ -54,11 +61,11 @@ MODULE_DEVICE_TABLE(i2c, ee1004_ids); /*-------------------------------------------------------------------------*/ -static int ee1004_get_current_page(void) +static int ee1004_get_current_page(struct ee1004_bus *bus) { int err; - err = i2c_smbus_read_byte(ee1004_set_page[0]); + err = i2c_smbus_read_byte(bus->set_page_clients[0]); if (err == -ENXIO) { /* Nack means page 1 is selected */ return 1; @@ -72,33 +79,30 @@ static int ee1004_get_current_page(void) return 0; } -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; - if (page == ee1004_current_page) + if (page == bus->page) return 0; /* Data is ignored */ - ret = i2c_smbus_write_byte(ee1004_set_page[page], 0x00); + ret = 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 == -ENXIO && ee1004_get_current_page() == page) + if (ret == -ENXIO && ee1004_get_current_page(bus) == page) ret = 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 = page; + bus->page = page; return 0; } -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 *client, char *buf, page = offset >> EE1004_PAGE_SHIFT; offset &= (1 << EE1004_PAGE_SHIFT) - 1; - status = ee1004_set_current_page(&client->dev, page); - if (status) + status = ee1004_set_current_page(bus, page); + if (status) { + dev_err(&client->dev, "Failed to select page %d (%d)\n", page, status); return status; + } /* Can't cross page boundaries */ if (offset + count > EE1004_PAGE_SIZE) @@ -125,6 +131,7 @@ static ssize_t eeprom_read(struct file *filp, struct kobject *kobj, char *buf, loff_t off, size_t count) { struct i2c_client *client = kobj_to_i2c_client(kobj); + struct ee1004_bus *bus = i2c_get_clientdata(client); size_t requested = count; int ret = 0; @@ -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); while (count) { - ret = ee1004_eeprom_read(client, buf, off, count); + ret = ee1004_eeprom_read(client, bus, buf, off, count); if (ret < 0) goto out; @@ -144,7 +151,7 @@ static ssize_t eeprom_read(struct file *filp, struct kobject *kobj, count -= ret; } out: - mutex_unlock(&ee1004_bus_lock); + mutex_unlock(&bus->lock); return ret < 0 ? ret : requested; } @@ -158,18 +165,56 @@ static struct bin_attribute *ee1004_attrs[] = { BIN_ATTRIBUTE_GROUPS(ee1004); -static void ee1004_cleanup(int idx) +static void ee1004_bus_unregister(struct ee1004_bus *bus) { - if (--ee1004_dev_count == 0) - while (--idx >= 0) { - i2c_unregister_device(ee1004_set_page[idx]); - ee1004_set_page[idx] = 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 = 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_adapter *adapter) +{ + bus->set_page_clients[0] = i2c_new_dummy_device(adapter, EE1004_ADDR_SET_PAGE0); + if (IS_ERR(bus->set_page_clients[0])) + return PTR_ERR(bus->set_page_clients[0]); + + bus->set_page_clients[1] = i2c_new_dummy_device(adapter, EE1004_ADDR_SET_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 = 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 = adapter; + + return 0; } static int ee1004_probe(struct i2c_client *client) { - int err, cnr = 0; + struct ee1004_bus *bus; + bool found = false; + int rc = 0; /* 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; - /* Use 2 dummy devices for page select command */ - mutex_lock(&ee1004_bus_lock); - if (++ee1004_dev_count == 1) { - for (cnr = 0; cnr < EE1004_NUM_PAGES; cnr++) { - struct i2c_client *cl; - - cl = i2c_new_dummy_device(client->adapter, EE1004_ADDR_SET_PAGE + cnr); - if (IS_ERR(cl)) { - err = PTR_ERR(cl); - goto err_clients; - } - ee1004_set_page[cnr] = cl; + mutex_lock(&ee1004_busses_lock); + list_for_each_entry(bus, &ee1004_busses, list) { + if (bus->adapter == client->adapter) { + kref_get(&bus->kref); + found = true; + break; + } + } + + if (!found) { + bus = kzalloc(sizeof(*bus), GFP_KERNEL); + if (!bus) { + rc = -ENOMEM; + goto unlock; } - /* Remember current page to avoid unneeded page select */ - err = ee1004_get_current_page(); - if (err < 0) - goto err_clients; - dev_dbg(&client->dev, "Currently selected page: %d\n", err); - ee1004_current_page = err; - } else if (client->adapter != ee1004_set_page[0]->adapter) { - dev_err(&client->dev, - "Driver only supports devices on a single I2C bus\n"); - err = -EOPNOTSUPP; - goto err_clients; + rc = ee1004_bus_initialize(bus, client->adapter); + if (rc) { + kfree(bus); + goto unlock; + } } - mutex_unlock(&ee1004_bus_lock); + + i2c_set_clientdata(client, bus); dev_info(&client->dev, "%u byte EE1004-compliant SPD EEPROM, read-only\n", EE1004_EEPROM_SIZE); - return 0; - - err_clients: - ee1004_cleanup(cnr); - mutex_unlock(&ee1004_bus_lock); - - return err; +unlock: + mutex_unlock(&ee1004_busses_lock); + return rc; } 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 = i2c_get_clientdata(client); + + kref_put(&bus->kref, ee1004_bus_release); } /*-------------------------------------------------------------------------*/