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Thu, 29 Sep 2022 08:03:57 +0000 From: Quan Nguyen To: Randy Dunlap , Wolfram Sang , Corey Minyard , Rob Herring , Krzysztof Kozlowski , Brendan Higgins , Benjamin Herrenschmidt , Joel Stanley , Andrew Jeffery , openipmi-developer@lists.sourceforge.net, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org, openbmc@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-aspeed@lists.ozlabs.org, Open Source Submission Cc: Phong Vo , thang@os.amperecomputing.com, Quan Nguyen Subject: [PATCH v9 1/3] ipmi: ssif_bmc: Add SSIF BMC driver Date: Thu, 29 Sep 2022 15:03:24 +0700 Message-Id: <20220929080326.752907-2-quan@os.amperecomputing.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220929080326.752907-1-quan@os.amperecomputing.com> References: <20220929080326.752907-1-quan@os.amperecomputing.com> X-ClientProxiedBy: SI2P153CA0002.APCP153.PROD.OUTLOOK.COM (2603:1096:4:140::16) To SJ0PR01MB7282.prod.exchangelabs.com (2603:10b6:a03:3f2::24) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ0PR01MB7282:EE_|CY4PR01MB2631:EE_ X-MS-Office365-Filtering-Correlation-Id: 9e101ede-61cf-44b7-572d-08daa1f128aa X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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Thanks Dan for the copy_from_user() fix in the link below. Link: https://lore.kernel.org/linux-arm-kernel/20220310114119.13736-4-quan@os.amperecomputing.com/ Signed-off-by: Quan Nguyen --- v9: + Fix dependence with I2C subsystem [Randy] + Remove useless error handling path [CJ] + Update comment for SSIF_ABORTING state [CJ] + Fix "unknown type name --u8" [kernel test robot] + Fix ssif_bmc_remove() to return void to align with recent kernel change [Quan] v8: + Dropped ssif_bmc.h file and move its content to ssif_bmc.c [Corey] + Add struct ipmi_ssif_msg to include/uapi/linux/ipmi_ssif_bmc.h header file [Corey] + Use unsigned int for len field in struct ipmi_ssif_msg [Corey] + Avoid using packed structure [Corey] + Add comment to clarify the logic flow [Corey] + Fix multipart read end with len=0 issue [Corey] + Refactor code handle the too big request message [Corey] + Fix code indentation issue [Corey] + Clean buffer before receiving request to avoid garbage [Quan] + Fix the license to SPDX-License-Identifier: GPL-2.0-only [Quan] v7: + Remove unneccessary del_timer() in response_timeout() [Corey] + Change compatible string from "ampere,ssif-bmc" to "ssif-bmc" [Jae] + Add MODULE_DEVICE_TABLE(of, ssif_bmc_match), fix blank line [Jae] + Dropped the use of ssif_msg_len() macro, use the len directly [Quan] + Solve possible issue if both response timer and ssif_bmc_write() occurred at the same time [Corey] + Fix wrong return type of ssif_bmc_poll() [kernel robot test] + Refactor and introduce ssif_part_buffer struct to replace the response_buf to manage each send/receive part of ssif [Quan] + Change SSIF_BAD_SMBUS state to SSIF_ABORTING state [Corey] + Support abort feature to skip the current bad request/response and wait until next new request [Corey] + Refactor the PEC calculation to avoid the re-calculate the PEC on each I2C_SLAVE_WRITE_RECEIVED event [Quan] + Fix the use of error-proned idx [Corey] + Defer the test for valid SMBus command until the read/write part is determined [Quan] + Change/split unsupported_smbus_cmd() to supported_[write|read]_cmd() [Corey] + Abort the request if somehow its size exceeded 255 bytes [Quan] v6: + Drop the use of slave_enable() [Wolfram] + Make i2c-aspeed to issue RxCmdLast command on all I2C_SLAVE_WRITE_REQUESTED event to assert NAK when slave busy [Quan] + Make i2c slave to return -EBUSY when it's busy [Quan] + Drop the aborting feature as return Completion Code 0xFF may stop host to retry and make ipmi_ssif.so fails to load [Quan] + Add timer to recover slave from busy state when no response [Quan] + Clean request/response buffer appropriately [Quan] + Add some minor change on error and warning messages [Quan] v5: + None v4: + Send response with Completion code 0xFF when aborting [Quan] + Added bounding check on SMBus writes and the whole request [Dan] + Moved buffer to end of struct ssif_bmc_ctx to avoid context corruption if somehow buffer is written past the end [Dan] + Return -EINVAL if userspace buffer too small, dont silence truncate [Corey, Joel] + Not necessary to check NONBLOCK in lock [Corey] + Enforce one user at a time [Joel] + Reject write with invalid response length from userspace [Corey] + Add state machines for better ssif bmc state handling [Quan] + Drop ssif_bmc_aspeed.c and make ssif_bmc.c is generic SSIF BMC driver [Quan] + Change compatible string "aspeed,ast2500-ssif-bmc" to "ampere,ssif-bmc" [Quan] + Abort current request with invalid SMBus write or invalid command [Quan] + Abort all request if there is pending response [Quan] + Changed validate_pec() to validate_request() [Quan] + Add unsupported_smbus_cmd() to handle unknown SMBus command [Quan] + Print internal state string for ease investigating issue [Quan] + Move to READY state on SLAVE_STOP event [Quan] + Change initilize_transfer() to process_smbus_cmd() [Quan] + Introduce functions for each slave event [Quan] v3: + Removed redundant license info [Joel] + Switched to use traditional if-else [Joel] + Removed unused ssif_bmc_ioctl() [Joel] + Made handle_request()/complete_response() to return void [Joel] + Refactored send_ssif_bmc_response() and receive_ssif_bmc_request() [Corey] + Removed mutex [Corey] + Use spin_lock/unlock_irqsave/restore in callback [Corey] + Removed the unnecessary memset [Corey] + Switch to use dev_err() [Corey] v2: + Fixed compiling error with COMPILE_TEST for arc drivers/char/ipmi/Kconfig | 10 + drivers/char/ipmi/Makefile | 1 + drivers/char/ipmi/ssif_bmc.c | 873 +++++++++++++++++++++++++++++ include/uapi/linux/ipmi_ssif_bmc.h | 18 + 4 files changed, 902 insertions(+) create mode 100644 drivers/char/ipmi/ssif_bmc.c create mode 100644 include/uapi/linux/ipmi_ssif_bmc.h diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig index 39565cf74b2c..b6c0d35fc1a5 100644 --- a/drivers/char/ipmi/Kconfig +++ b/drivers/char/ipmi/Kconfig @@ -169,6 +169,16 @@ config ASPEED_BT_IPMI_BMC found on Aspeed SOCs (AST2400 and AST2500). The driver implements the BMC side of the BT interface. +config SSIF_IPMI_BMC + tristate "SSIF IPMI BMC driver" + depends on I2C && I2C_SLAVE + help + This enables the IPMI SMBus system interface (SSIF) at the + management (BMC) side. + + The driver implements the BMC side of the SMBus system + interface (SSIF). + config IPMB_DEVICE_INTERFACE tristate 'IPMB Interface handler' depends on I2C diff --git a/drivers/char/ipmi/Makefile b/drivers/char/ipmi/Makefile index 7ce790efad92..cb6138b8ded9 100644 --- a/drivers/char/ipmi/Makefile +++ b/drivers/char/ipmi/Makefile @@ -30,3 +30,4 @@ obj-$(CONFIG_ASPEED_BT_IPMI_BMC) += bt-bmc.o obj-$(CONFIG_ASPEED_KCS_IPMI_BMC) += kcs_bmc_aspeed.o obj-$(CONFIG_NPCM7XX_KCS_IPMI_BMC) += kcs_bmc_npcm7xx.o obj-$(CONFIG_IPMB_DEVICE_INTERFACE) += ipmb_dev_int.o +obj-$(CONFIG_SSIF_IPMI_BMC) += ssif_bmc.o diff --git a/drivers/char/ipmi/ssif_bmc.c b/drivers/char/ipmi/ssif_bmc.c new file mode 100644 index 000000000000..a7bb4b99000e --- /dev/null +++ b/drivers/char/ipmi/ssif_bmc.c @@ -0,0 +1,873 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * The driver for BMC side of SSIF interface + * + * Copyright (c) 2022, Ampere Computing LLC + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define DEVICE_NAME "ipmi-ssif-host" + +#define GET_8BIT_ADDR(addr_7bit) (((addr_7bit) << 1) & 0xff) + +/* A standard SMBus Transaction is limited to 32 data bytes */ +#define MAX_PAYLOAD_PER_TRANSACTION 32 +/* Transaction includes the address, the command, the length and the PEC byte */ +#define MAX_TRANSACTION (MAX_PAYLOAD_PER_TRANSACTION + 4) + +#define MAX_IPMI_DATA_PER_START_TRANSACTION 30 +#define MAX_IPMI_DATA_PER_MIDDLE_TRANSACTION 31 + +#define SSIF_IPMI_SINGLEPART_WRITE 0x2 +#define SSIF_IPMI_SINGLEPART_READ 0x3 +#define SSIF_IPMI_MULTIPART_WRITE_START 0x6 +#define SSIF_IPMI_MULTIPART_WRITE_MIDDLE 0x7 +#define SSIF_IPMI_MULTIPART_WRITE_END 0x8 +#define SSIF_IPMI_MULTIPART_READ_START 0x3 +#define SSIF_IPMI_MULTIPART_READ_MIDDLE 0x9 + +/* + * IPMI 2.0 Spec, section 12.7 SSIF Timing, + * Request-to-Response Time is T6max(250ms) - T1max(20ms) - 3ms = 227ms + * Recover ssif_bmc from busy state if it takes up to 500ms + */ +#define RESPONSE_TIMEOUT 500 /* ms */ + +struct ssif_part_buffer { + u8 address; + u8 smbus_cmd; + u8 length; + u8 payload[MAX_PAYLOAD_PER_TRANSACTION]; + u8 pec; + u8 index; +}; + +/* + * SSIF internal states: + * SSIF_READY 0x00 : Ready state + * SSIF_START 0x01 : Start smbus transaction + * SSIF_SMBUS_CMD 0x02 : Received SMBus command + * SSIF_REQ_RECVING 0x03 : Receiving request + * SSIF_RES_SENDING 0x04 : Sending response + * SSIF_ABORTING 0x05 : Aborting state + */ +enum ssif_state { + SSIF_READY, + SSIF_START, + SSIF_SMBUS_CMD, + SSIF_REQ_RECVING, + SSIF_RES_SENDING, + SSIF_ABORTING, + SSIF_STATE_MAX +}; + +struct ssif_bmc_ctx { + struct i2c_client *client; + struct miscdevice miscdev; + int msg_idx; + bool pec_support; + /* ssif bmc spinlock */ + spinlock_t lock; + wait_queue_head_t wait_queue; + u8 running; + enum ssif_state state; + /* Timeout waiting for response */ + struct timer_list response_timer; + bool response_timer_inited; + /* Flag to identify a Multi-part Read Transaction */ + bool is_singlepart_read; + u8 nbytes_processed; + u8 remain_len; + u8 recv_len; + /* Block Number of a Multi-part Read Transaction */ + u8 block_num; + bool request_available; + bool response_in_progress; + bool busy; + bool aborting; + /* Buffer for SSIF Transaction part*/ + struct ssif_part_buffer part_buf; + struct ipmi_ssif_msg response; + struct ipmi_ssif_msg request; +}; + +static inline struct ssif_bmc_ctx *to_ssif_bmc(struct file *file) +{ + return container_of(file->private_data, struct ssif_bmc_ctx, miscdev); +} + +static const char *state_to_string(enum ssif_state state) +{ + switch (state) { + case SSIF_READY: + return "SSIF_READY"; + case SSIF_START: + return "SSIF_START"; + case SSIF_SMBUS_CMD: + return "SSIF_SMBUS_CMD"; + case SSIF_REQ_RECVING: + return "SSIF_REQ_RECVING"; + case SSIF_RES_SENDING: + return "SSIF_RES_SENDING"; + case SSIF_ABORTING: + return "SSIF_ABORTING"; + default: + return "SSIF_STATE_UNKNOWN"; + } +} + +/* Handle SSIF message that will be sent to user */ +static ssize_t ssif_bmc_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) +{ + struct ssif_bmc_ctx *ssif_bmc = to_ssif_bmc(file); + struct ipmi_ssif_msg msg; + unsigned long flags; + ssize_t ret; + + spin_lock_irqsave(&ssif_bmc->lock, flags); + while (!ssif_bmc->request_available) { + spin_unlock_irqrestore(&ssif_bmc->lock, flags); + if (file->f_flags & O_NONBLOCK) + return -EAGAIN; + ret = wait_event_interruptible(ssif_bmc->wait_queue, + ssif_bmc->request_available); + if (ret) + return ret; + spin_lock_irqsave(&ssif_bmc->lock, flags); + } + + if (count < min_t(ssize_t, + sizeof_field(struct ipmi_ssif_msg, len) + ssif_bmc->request.len, + sizeof(struct ipmi_ssif_msg))) { + spin_unlock_irqrestore(&ssif_bmc->lock, flags); + ret = -EINVAL; + } else { + count = min_t(ssize_t, + sizeof_field(struct ipmi_ssif_msg, len) + ssif_bmc->request.len, + sizeof(struct ipmi_ssif_msg)); + memcpy(&msg, &ssif_bmc->request, count); + ssif_bmc->request_available = false; + spin_unlock_irqrestore(&ssif_bmc->lock, flags); + + ret = copy_to_user(buf, &msg, count); + } + + return (ret < 0) ? ret : count; +} + +/* Handle SSIF message that is written by user */ +static ssize_t ssif_bmc_write(struct file *file, const char __user *buf, size_t count, + loff_t *ppos) +{ + struct ssif_bmc_ctx *ssif_bmc = to_ssif_bmc(file); + struct ipmi_ssif_msg msg; + unsigned long flags; + ssize_t ret; + + if (count > sizeof(struct ipmi_ssif_msg)) + return -EINVAL; + + if (copy_from_user(&msg, buf, count)) + return -EFAULT; + + if (!msg.len || count < sizeof_field(struct ipmi_ssif_msg, len) + msg.len) + return -EINVAL; + + spin_lock_irqsave(&ssif_bmc->lock, flags); + while (ssif_bmc->response_in_progress) { + spin_unlock_irqrestore(&ssif_bmc->lock, flags); + if (file->f_flags & O_NONBLOCK) + return -EAGAIN; + ret = wait_event_interruptible(ssif_bmc->wait_queue, + !ssif_bmc->response_in_progress); + if (ret) + return ret; + spin_lock_irqsave(&ssif_bmc->lock, flags); + } + + /* + * The write must complete before the response timeout fired, otherwise + * the response is aborted and wait for next request + * Return -EINVAL if the response is aborted + */ + ret = (ssif_bmc->response_timer_inited) ? 0 : -EINVAL; + if (ret) + goto exit; + + del_timer(&ssif_bmc->response_timer); + ssif_bmc->response_timer_inited = false; + + memcpy(&ssif_bmc->response, &msg, count); + ssif_bmc->is_singlepart_read = (msg.len <= MAX_PAYLOAD_PER_TRANSACTION); + + ssif_bmc->response_in_progress = true; + + /* ssif_bmc not busy */ + ssif_bmc->busy = false; + + /* Clean old request buffer */ + memset(&ssif_bmc->request, 0, sizeof(struct ipmi_ssif_msg)); +exit: + spin_unlock_irqrestore(&ssif_bmc->lock, flags); + + return (ret < 0) ? ret : count; +} + +static int ssif_bmc_open(struct inode *inode, struct file *file) +{ + struct ssif_bmc_ctx *ssif_bmc = to_ssif_bmc(file); + int ret = 0; + + spin_lock_irq(&ssif_bmc->lock); + if (!ssif_bmc->running) + ssif_bmc->running = 1; + else + ret = -EBUSY; + spin_unlock_irq(&ssif_bmc->lock); + + return ret; +} + +static __poll_t ssif_bmc_poll(struct file *file, poll_table *wait) +{ + struct ssif_bmc_ctx *ssif_bmc = to_ssif_bmc(file); + __poll_t mask = 0; + + poll_wait(file, &ssif_bmc->wait_queue, wait); + + spin_lock_irq(&ssif_bmc->lock); + /* The request is available, userspace application can get the request */ + if (ssif_bmc->request_available) + mask |= POLLIN; + + spin_unlock_irq(&ssif_bmc->lock); + + return mask; +} + +static int ssif_bmc_release(struct inode *inode, struct file *file) +{ + struct ssif_bmc_ctx *ssif_bmc = to_ssif_bmc(file); + + spin_lock_irq(&ssif_bmc->lock); + ssif_bmc->running = 0; + spin_unlock_irq(&ssif_bmc->lock); + + return 0; +} + +/* + * System calls to device interface for user apps + */ +static const struct file_operations ssif_bmc_fops = { + .owner = THIS_MODULE, + .open = ssif_bmc_open, + .read = ssif_bmc_read, + .write = ssif_bmc_write, + .release = ssif_bmc_release, + .poll = ssif_bmc_poll, +}; + +/* Called with ssif_bmc->lock held. */ +static void complete_response(struct ssif_bmc_ctx *ssif_bmc) +{ + /* Invalidate response in buffer to denote it having been sent. */ + ssif_bmc->response.len = 0; + ssif_bmc->response_in_progress = false; + ssif_bmc->nbytes_processed = 0; + ssif_bmc->remain_len = 0; + ssif_bmc->busy = false; + memset(&ssif_bmc->part_buf, 0, sizeof(struct ssif_part_buffer)); + wake_up_all(&ssif_bmc->wait_queue); +} + +static void response_timeout(struct timer_list *t) +{ + struct ssif_bmc_ctx *ssif_bmc = from_timer(ssif_bmc, t, response_timer); + unsigned long flags; + + spin_lock_irqsave(&ssif_bmc->lock, flags); + + /* Do nothing if the response is in progress */ + if (!ssif_bmc->response_in_progress) { + /* Recover ssif_bmc from busy */ + ssif_bmc->busy = false; + ssif_bmc->response_timer_inited = false; + /* Set aborting flag */ + ssif_bmc->aborting = true; + } + + spin_unlock_irqrestore(&ssif_bmc->lock, flags); +} + +/* Called with ssif_bmc->lock held. */ +static void handle_request(struct ssif_bmc_ctx *ssif_bmc) +{ + /* set ssif_bmc to busy waiting for response */ + ssif_bmc->busy = true; + /* Request message is available to process */ + ssif_bmc->request_available = true; + /* Clean old response buffer */ + memset(&ssif_bmc->response, 0, sizeof(struct ipmi_ssif_msg)); + /* This is the new READ request.*/ + wake_up_all(&ssif_bmc->wait_queue); + + /* Armed timer to recover slave from busy state in case of no response */ + if (!ssif_bmc->response_timer_inited) { + timer_setup(&ssif_bmc->response_timer, response_timeout, 0); + ssif_bmc->response_timer_inited = true; + } + mod_timer(&ssif_bmc->response_timer, jiffies + msecs_to_jiffies(RESPONSE_TIMEOUT)); +} + +static void calculate_response_part_pec(struct ssif_part_buffer *part) +{ + u8 addr = part->address; + + /* PEC - Start Read Address */ + part->pec = i2c_smbus_pec(0, &addr, 1); + /* PEC - SSIF Command */ + part->pec = i2c_smbus_pec(part->pec, &part->smbus_cmd, 1); + /* PEC - Restart Write Address */ + addr = addr | 0x01; + part->pec = i2c_smbus_pec(part->pec, &addr, 1); + part->pec = i2c_smbus_pec(part->pec, &part->length, 1); + if (part->length) + part->pec = i2c_smbus_pec(part->pec, part->payload, part->length); +} + +static void set_singlepart_response_buffer(struct ssif_bmc_ctx *ssif_bmc) +{ + struct ssif_part_buffer *part = &ssif_bmc->part_buf; + + part->address = GET_8BIT_ADDR(ssif_bmc->client->addr); + part->length = (u8)ssif_bmc->response.len; + + /* Clear the rest to 0 */ + memset(part->payload + part->length, 0, MAX_PAYLOAD_PER_TRANSACTION - part->length); + memcpy(&part->payload[0], &ssif_bmc->response.payload[0], part->length); +} + +static void set_multipart_response_buffer(struct ssif_bmc_ctx *ssif_bmc) +{ + struct ssif_part_buffer *part = &ssif_bmc->part_buf; + u8 part_len = 0; + + part->address = GET_8BIT_ADDR(ssif_bmc->client->addr); + switch (part->smbus_cmd) { + case SSIF_IPMI_MULTIPART_READ_START: + /* + * Read Start length is 32 bytes. + * Read Start transfer first 30 bytes of IPMI response + * and 2 special code 0x00, 0x01. + */ + ssif_bmc->nbytes_processed = 0; + ssif_bmc->block_num = 0; + part->length = MAX_PAYLOAD_PER_TRANSACTION; + part_len = MAX_IPMI_DATA_PER_START_TRANSACTION; + ssif_bmc->remain_len = ssif_bmc->response.len - part_len; + + part->payload[0] = 0x00; /* Start Flag */ + part->payload[1] = 0x01; /* Start Flag */ + + memcpy(&part->payload[2], &ssif_bmc->response.payload[0], part_len); + break; + + case SSIF_IPMI_MULTIPART_READ_MIDDLE: + /* + * IPMI READ Middle or READ End messages can carry up to 31 bytes + * IPMI data plus block number byte. + */ + if (ssif_bmc->remain_len <= MAX_IPMI_DATA_PER_MIDDLE_TRANSACTION) { + /* + * This is READ End message + * Return length is the remaining response data length + * plus block number + * Block number 0xFF is to indicate this is last message + * + */ + /* Clean the buffer */ + memset(&part->payload[0], 0, MAX_PAYLOAD_PER_TRANSACTION); + part->length = ssif_bmc->remain_len + 1; + part_len = ssif_bmc->remain_len; + ssif_bmc->block_num = 0xFF; + part->payload[0] = ssif_bmc->block_num; + } else { + /* + * This is READ Middle message + * Response length is the maximum SMBUS transfer length + * Block number byte is incremented + * Return length is maximum SMBUS transfer length + */ + part->length = MAX_PAYLOAD_PER_TRANSACTION; + part_len = MAX_IPMI_DATA_PER_MIDDLE_TRANSACTION; + part->payload[0] = ssif_bmc->block_num; + ssif_bmc->block_num++; + } + + ssif_bmc->remain_len -= part_len; + memcpy(&part->payload[1], ssif_bmc->response.payload + ssif_bmc->nbytes_processed, + part_len); + break; + + default: + /* Do not expect to go to this case */ + dev_err(&ssif_bmc->client->dev, "%s: Unexpected SMBus command 0x%x\n", + __func__, part->smbus_cmd); + break; + } + + ssif_bmc->nbytes_processed += part_len; +} + +static bool supported_read_cmd(u8 cmd) +{ + if (cmd == SSIF_IPMI_SINGLEPART_READ || + cmd == SSIF_IPMI_MULTIPART_READ_START || + cmd == SSIF_IPMI_MULTIPART_READ_MIDDLE) + return true; + + return false; +} + +static bool supported_write_cmd(u8 cmd) +{ + if (cmd == SSIF_IPMI_SINGLEPART_WRITE || + cmd == SSIF_IPMI_MULTIPART_WRITE_START || + cmd == SSIF_IPMI_MULTIPART_WRITE_MIDDLE || + cmd == SSIF_IPMI_MULTIPART_WRITE_END) + return true; + + return false; +} + +/* Process the IPMI response that will be read by master */ +static void handle_read_processed(struct ssif_bmc_ctx *ssif_bmc, u8 *val) +{ + struct ssif_part_buffer *part = &ssif_bmc->part_buf; + + /* msg_idx start from 0 */ + if (part->index < part->length) + *val = part->payload[part->index]; + else if (part->index == part->length && ssif_bmc->pec_support) + *val = part->pec; + else + *val = 0; + + part->index++; +} + +static void handle_write_received(struct ssif_bmc_ctx *ssif_bmc, u8 *val) +{ + /* + * The msg_idx must be 1 when first enter SSIF_REQ_RECVING state + * And it would never exceeded 36 bytes included the 32 bytes max payload + + * the address + the command + the len and the PEC. + */ + if (ssif_bmc->msg_idx < 1 || ssif_bmc->msg_idx > MAX_TRANSACTION) + return; + + if (ssif_bmc->msg_idx == 1) { + ssif_bmc->part_buf.length = *val; + ssif_bmc->part_buf.index = 0; + } else { + ssif_bmc->part_buf.payload[ssif_bmc->part_buf.index++] = *val; + } + + ssif_bmc->msg_idx++; +} + +static bool validate_request_part(struct ssif_bmc_ctx *ssif_bmc) +{ + struct ssif_part_buffer *part = &ssif_bmc->part_buf; + bool ret = true; + u8 cpec; + u8 addr; + + if (part->index == part->length) { + /* PEC is not included */ + ssif_bmc->pec_support = false; + ret = true; + goto exit; + } + + if (part->index != part->length + 1) { + ret = false; + goto exit; + } + + /* PEC is included */ + ssif_bmc->pec_support = true; + part->pec = part->payload[part->length]; + addr = GET_8BIT_ADDR(ssif_bmc->client->addr); + cpec = i2c_smbus_pec(0, &addr, 1); + cpec = i2c_smbus_pec(cpec, &part->smbus_cmd, 1); + cpec = i2c_smbus_pec(cpec, &part->length, 1); + /* + * As SMBus specification does not allow the length + * (byte count) in the Write-Block protocol to be zero. + * Therefore, it is illegal to have the last Middle + * transaction in the sequence carry 32-byte and have + * a length of ‘0’ in the End transaction. + * But some users may try to use this way and we should + * prevent ssif_bmc driver broken in this case. + */ + if (part->length) + cpec = i2c_smbus_pec(cpec, part->payload, part->length); + + if (cpec != part->pec) + ret = false; + +exit: + return ret; +} + +static void process_request_part(struct ssif_bmc_ctx *ssif_bmc) +{ + struct ssif_part_buffer *part = &ssif_bmc->part_buf; + unsigned int len; + + switch (part->smbus_cmd) { + case SSIF_IPMI_SINGLEPART_WRITE: + /* save the whole part to request*/ + ssif_bmc->request.len = part->length; + memcpy(ssif_bmc->request.payload, part->payload, part->length); + + break; + case SSIF_IPMI_MULTIPART_WRITE_START: + ssif_bmc->request.len = 0; + + fallthrough; + case SSIF_IPMI_MULTIPART_WRITE_MIDDLE: + case SSIF_IPMI_MULTIPART_WRITE_END: + len = ssif_bmc->request.len + part->length; + /* Do the bound check here, not allow the request len exceed 254 bytes */ + if (len > IPMI_SSIF_PAYLOAD_MAX) { + dev_warn(&ssif_bmc->client->dev, + "Warn: Request exceeded 254 bytes, aborting"); + /* Request too long, aborting */ + ssif_bmc->aborting = true; + } else { + memcpy(ssif_bmc->request.payload + ssif_bmc->request.len, + part->payload, part->length); + ssif_bmc->request.len += part->length; + } + break; + default: + /* Do not expect to go to this case */ + dev_err(&ssif_bmc->client->dev, "%s: Unexpected SMBus command 0x%x\n", + __func__, part->smbus_cmd); + break; + } +} + +static void process_smbus_cmd(struct ssif_bmc_ctx *ssif_bmc, u8 *val) +{ + /* SMBUS command can vary (single or multi-part) */ + ssif_bmc->part_buf.smbus_cmd = *val; + ssif_bmc->msg_idx = 1; + memset(&ssif_bmc->part_buf.payload[0], 0, MAX_PAYLOAD_PER_TRANSACTION); + + if (*val == SSIF_IPMI_SINGLEPART_WRITE || *val == SSIF_IPMI_MULTIPART_WRITE_START) { + /* + * The response maybe not come in-time, causing host SSIF driver + * to timeout and resend a new request. In such case check for + * pending response and clear it + */ + if (ssif_bmc->response_in_progress) + complete_response(ssif_bmc); + + /* This is new request, flip aborting flag if set */ + if (ssif_bmc->aborting) + ssif_bmc->aborting = false; + } +} + +static void on_read_requested_event(struct ssif_bmc_ctx *ssif_bmc, u8 *val) +{ + if (ssif_bmc->state == SSIF_READY || + ssif_bmc->state == SSIF_START || + ssif_bmc->state == SSIF_REQ_RECVING || + ssif_bmc->state == SSIF_RES_SENDING) { + dev_warn(&ssif_bmc->client->dev, + "Warn: %s unexpected READ REQUESTED in state=%s\n", + __func__, state_to_string(ssif_bmc->state)); + ssif_bmc->state = SSIF_ABORTING; + *val = 0; + return; + + } else if (ssif_bmc->state == SSIF_SMBUS_CMD) { + if (!supported_read_cmd(ssif_bmc->part_buf.smbus_cmd)) { + dev_warn(&ssif_bmc->client->dev, "Warn: Unknown SMBus read command=0x%x", + ssif_bmc->part_buf.smbus_cmd); + ssif_bmc->aborting = true; + } + + if (ssif_bmc->aborting) + ssif_bmc->state = SSIF_ABORTING; + else + ssif_bmc->state = SSIF_RES_SENDING; + } + + ssif_bmc->msg_idx = 0; + + /* Send 0 if there is nothing to send */ + if (!ssif_bmc->response_in_progress || ssif_bmc->state == SSIF_ABORTING) { + *val = 0; + return; + } + + if (ssif_bmc->is_singlepart_read) + set_singlepart_response_buffer(ssif_bmc); + else + set_multipart_response_buffer(ssif_bmc); + + calculate_response_part_pec(&ssif_bmc->part_buf); + ssif_bmc->part_buf.index = 0; + *val = ssif_bmc->part_buf.length; +} + +static void on_read_processed_event(struct ssif_bmc_ctx *ssif_bmc, u8 *val) +{ + if (ssif_bmc->state == SSIF_READY || + ssif_bmc->state == SSIF_START || + ssif_bmc->state == SSIF_REQ_RECVING || + ssif_bmc->state == SSIF_SMBUS_CMD) { + dev_warn(&ssif_bmc->client->dev, + "Warn: %s unexpected READ PROCESSED in state=%s\n", + __func__, state_to_string(ssif_bmc->state)); + ssif_bmc->state = SSIF_ABORTING; + *val = 0; + return; + } + + /* Send 0 if there is nothing to send */ + if (!ssif_bmc->response_in_progress || ssif_bmc->state == SSIF_ABORTING) { + *val = 0; + return; + } + + handle_read_processed(ssif_bmc, val); +} + +static void on_write_requested_event(struct ssif_bmc_ctx *ssif_bmc, u8 *val) +{ + if (ssif_bmc->state == SSIF_READY || ssif_bmc->state == SSIF_SMBUS_CMD) { + ssif_bmc->state = SSIF_START; + + } else if (ssif_bmc->state == SSIF_START || + ssif_bmc->state == SSIF_REQ_RECVING || + ssif_bmc->state == SSIF_RES_SENDING) { + dev_warn(&ssif_bmc->client->dev, + "Warn: %s unexpected WRITE REQUEST in state=%s\n", + __func__, state_to_string(ssif_bmc->state)); + ssif_bmc->state = SSIF_ABORTING; + return; + } + + ssif_bmc->msg_idx = 0; + ssif_bmc->part_buf.address = *val; +} + +static void on_write_received_event(struct ssif_bmc_ctx *ssif_bmc, u8 *val) +{ + if (ssif_bmc->state == SSIF_READY || + ssif_bmc->state == SSIF_RES_SENDING) { + dev_warn(&ssif_bmc->client->dev, + "Warn: %s unexpected WRITE RECEIVED in state=%s\n", + __func__, state_to_string(ssif_bmc->state)); + ssif_bmc->state = SSIF_ABORTING; + + } else if (ssif_bmc->state == SSIF_START) { + ssif_bmc->state = SSIF_SMBUS_CMD; + + } else if (ssif_bmc->state == SSIF_SMBUS_CMD) { + if (!supported_write_cmd(ssif_bmc->part_buf.smbus_cmd)) { + dev_warn(&ssif_bmc->client->dev, "Warn: Unknown SMBus write command=0x%x", + ssif_bmc->part_buf.smbus_cmd); + ssif_bmc->aborting = true; + } + + if (ssif_bmc->aborting) + ssif_bmc->state = SSIF_ABORTING; + else + ssif_bmc->state = SSIF_REQ_RECVING; + } + + /* This is response sending state */ + if (ssif_bmc->state == SSIF_REQ_RECVING) + handle_write_received(ssif_bmc, val); + else if (ssif_bmc->state == SSIF_SMBUS_CMD) + process_smbus_cmd(ssif_bmc, val); +} + +static void on_stop_event(struct ssif_bmc_ctx *ssif_bmc, u8 *val) +{ + if (ssif_bmc->state == SSIF_READY || + ssif_bmc->state == SSIF_START || + ssif_bmc->state == SSIF_SMBUS_CMD || + ssif_bmc->state == SSIF_ABORTING) { + dev_warn(&ssif_bmc->client->dev, + "Warn: %s unexpected SLAVE STOP in state=%s\n", + __func__, state_to_string(ssif_bmc->state)); + ssif_bmc->state = SSIF_READY; + + } else if (ssif_bmc->state == SSIF_REQ_RECVING) { + if (validate_request_part(ssif_bmc)) { + process_request_part(ssif_bmc); + if (ssif_bmc->part_buf.smbus_cmd == SSIF_IPMI_SINGLEPART_WRITE || + ssif_bmc->part_buf.smbus_cmd == SSIF_IPMI_MULTIPART_WRITE_END) + handle_request(ssif_bmc); + ssif_bmc->state = SSIF_READY; + } else { + /* + * A BMC that receives an invalid request drop the data for the write + * transaction and any further transactions (read or write) until + * the next valid read or write Start transaction is received + */ + dev_err(&ssif_bmc->client->dev, "Error: invalid pec\n"); + ssif_bmc->aborting = true; + } + } else if (ssif_bmc->state == SSIF_RES_SENDING) { + if (ssif_bmc->is_singlepart_read || ssif_bmc->block_num == 0xFF) + /* Invalidate response buffer to denote it is sent */ + complete_response(ssif_bmc); + ssif_bmc->state = SSIF_READY; + } + + /* Reset message index */ + ssif_bmc->msg_idx = 0; +} + +/* + * Callback function to handle I2C slave events + */ +static int ssif_bmc_cb(struct i2c_client *client, enum i2c_slave_event event, u8 *val) +{ + unsigned long flags; + struct ssif_bmc_ctx *ssif_bmc = i2c_get_clientdata(client); + int ret = 0; + + spin_lock_irqsave(&ssif_bmc->lock, flags); + + switch (event) { + case I2C_SLAVE_READ_REQUESTED: + on_read_requested_event(ssif_bmc, val); + break; + + case I2C_SLAVE_WRITE_REQUESTED: + on_write_requested_event(ssif_bmc, val); + break; + + case I2C_SLAVE_READ_PROCESSED: + on_read_processed_event(ssif_bmc, val); + break; + + case I2C_SLAVE_WRITE_RECEIVED: + on_write_received_event(ssif_bmc, val); + break; + + case I2C_SLAVE_STOP: + on_stop_event(ssif_bmc, val); + break; + + default: + dev_warn(&ssif_bmc->client->dev, "Warn: Unknown i2c slave event\n"); + break; + } + + if (!ssif_bmc->aborting && ssif_bmc->busy) + ret = -EBUSY; + + spin_unlock_irqrestore(&ssif_bmc->lock, flags); + + return ret; +} + +static int ssif_bmc_probe(struct i2c_client *client, const struct i2c_device_id *id) +{ + struct ssif_bmc_ctx *ssif_bmc; + int ret; + + ssif_bmc = devm_kzalloc(&client->dev, sizeof(*ssif_bmc), GFP_KERNEL); + if (!ssif_bmc) + return -ENOMEM; + + spin_lock_init(&ssif_bmc->lock); + + init_waitqueue_head(&ssif_bmc->wait_queue); + ssif_bmc->request_available = false; + ssif_bmc->response_in_progress = false; + ssif_bmc->busy = false; + ssif_bmc->response_timer_inited = false; + + /* Register misc device interface */ + ssif_bmc->miscdev.minor = MISC_DYNAMIC_MINOR; + ssif_bmc->miscdev.name = DEVICE_NAME; + ssif_bmc->miscdev.fops = &ssif_bmc_fops; + ssif_bmc->miscdev.parent = &client->dev; + ret = misc_register(&ssif_bmc->miscdev); + if (ret) + return ret; + + ssif_bmc->client = client; + ssif_bmc->client->flags |= I2C_CLIENT_SLAVE; + + /* Register I2C slave */ + i2c_set_clientdata(client, ssif_bmc); + ret = i2c_slave_register(client, ssif_bmc_cb); + if (ret) + misc_deregister(&ssif_bmc->miscdev); + + return ret; +} + +static void ssif_bmc_remove(struct i2c_client *client) +{ + struct ssif_bmc_ctx *ssif_bmc = i2c_get_clientdata(client); + + i2c_slave_unregister(client); + misc_deregister(&ssif_bmc->miscdev); +} + +static const struct of_device_id ssif_bmc_match[] = { + { .compatible = "ssif-bmc" }, + { }, +}; +MODULE_DEVICE_TABLE(of, ssif_bmc_match); + +static const struct i2c_device_id ssif_bmc_id[] = { + { DEVICE_NAME, 0 }, + { }, +}; +MODULE_DEVICE_TABLE(i2c, ssif_bmc_id); + +static struct i2c_driver ssif_bmc_driver = { + .driver = { + .name = DEVICE_NAME, + .of_match_table = ssif_bmc_match, + }, + .probe = ssif_bmc_probe, + .remove = ssif_bmc_remove, + .id_table = ssif_bmc_id, +}; + +module_i2c_driver(ssif_bmc_driver); + +MODULE_AUTHOR("Quan Nguyen "); +MODULE_AUTHOR("Chuong Tran "); +MODULE_DESCRIPTION("Linux device driver of the BMC IPMI SSIF interface."); +MODULE_LICENSE("GPL"); diff --git a/include/uapi/linux/ipmi_ssif_bmc.h b/include/uapi/linux/ipmi_ssif_bmc.h new file mode 100644 index 000000000000..1c6a753dad08 --- /dev/null +++ b/include/uapi/linux/ipmi_ssif_bmc.h @@ -0,0 +1,18 @@ +/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note*/ +/* + * Copyright (c) 2022, Ampere Computing LLC. + */ + +#ifndef _UAPI_LINUX_IPMI_SSIF_BMC_H +#define _UAPI_LINUX_IPMI_SSIF_BMC_H + +#include + +/* Max length of ipmi ssif message included netfn and cmd field */ +#define IPMI_SSIF_PAYLOAD_MAX 254 +struct ipmi_ssif_msg { + unsigned int len; + __u8 payload[IPMI_SSIF_PAYLOAD_MAX]; +}; + +#endif /* _UAPI_LINUX_IPMI_SSIF_BMC_H */ From patchwork Thu Sep 29 08:03:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Quan Nguyen X-Patchwork-Id: 611936 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 31C91C07E9D for ; Thu, 29 Sep 2022 08:04:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235391AbiI2IEZ (ORCPT ); Thu, 29 Sep 2022 04:04:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50378 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235316AbiI2IEK (ORCPT ); Thu, 29 Sep 2022 04:04:10 -0400 Received: from NAM12-DM6-obe.outbound.protection.outlook.com (mail-dm6nam12on2131.outbound.protection.outlook.com [40.107.243.131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 74CD82A734; 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Thu, 29 Sep 2022 08:04:02 +0000 From: Quan Nguyen To: Randy Dunlap , Wolfram Sang , Corey Minyard , Rob Herring , Krzysztof Kozlowski , Brendan Higgins , Benjamin Herrenschmidt , Joel Stanley , Andrew Jeffery , openipmi-developer@lists.sourceforge.net, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org, openbmc@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-aspeed@lists.ozlabs.org, Open Source Submission Cc: Phong Vo , thang@os.amperecomputing.com, Quan Nguyen , Rob Herring Subject: [PATCH v9 2/3] bindings: ipmi: Add binding for SSIF BMC driver Date: Thu, 29 Sep 2022 15:03:25 +0700 Message-Id: <20220929080326.752907-3-quan@os.amperecomputing.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220929080326.752907-1-quan@os.amperecomputing.com> References: <20220929080326.752907-1-quan@os.amperecomputing.com> X-ClientProxiedBy: SI2P153CA0002.APCP153.PROD.OUTLOOK.COM (2603:1096:4:140::16) To SJ0PR01MB7282.prod.exchangelabs.com (2603:10b6:a03:3f2::24) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ0PR01MB7282:EE_|LV2PR01MB7885:EE_ X-MS-Office365-Filtering-Correlation-Id: a84d68aa-4932-4590-672e-08daa1f12bfb X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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Signed-off-by: Quan Nguyen Reviewed-by: Rob Herring --- v9: + Update missing Reviewed-by tag from v7 [Rob] v8: + None v7: + Change compatible string from "ampere,ssif-bmc" to "ssif-bmc" [Jae] v6: + None v5: + None v4: + Fix warning with dt_binding_check [Rob] + Change aspeed-ssif-bmc.yaml to ssif-bmc.yaml [Quan] v3: + Switched to use DT schema format [Rob] v2: + None .../devicetree/bindings/ipmi/ssif-bmc.yaml | 38 +++++++++++++++++++ 1 file changed, 38 insertions(+) create mode 100644 Documentation/devicetree/bindings/ipmi/ssif-bmc.yaml diff --git a/Documentation/devicetree/bindings/ipmi/ssif-bmc.yaml b/Documentation/devicetree/bindings/ipmi/ssif-bmc.yaml new file mode 100644 index 000000000000..02b662d780bb --- /dev/null +++ b/Documentation/devicetree/bindings/ipmi/ssif-bmc.yaml @@ -0,0 +1,38 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/ipmi/ssif-bmc.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: SSIF IPMI BMC interface + +description: SSIF IPMI BMC device bindings + +maintainers: + - Quan Nguyen + +properties: + compatible: + enum: + - ssif-bmc + + reg: + maxItems: 1 + +required: + - compatible + - reg + +additionalProperties: false + +examples: + - | + i2c { + #address-cells = <1>; + #size-cells = <0>; + + ssif-bmc@10 { + compatible = "ssif-bmc"; + reg = <0x10>; + }; + }; From patchwork Thu Sep 29 08:03:26 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Quan Nguyen X-Patchwork-Id: 610692 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 CE9BFC6FA82 for ; Thu, 29 Sep 2022 08:04:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235370AbiI2IE0 (ORCPT ); Thu, 29 Sep 2022 04:04:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50718 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235349AbiI2IEY (ORCPT ); Thu, 29 Sep 2022 04:04:24 -0400 Received: from NAM12-DM6-obe.outbound.protection.outlook.com (mail-dm6nam12on2131.outbound.protection.outlook.com [40.107.243.131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5EBA437FAF; 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Thu, 29 Sep 2022 08:04:08 +0000 From: Quan Nguyen To: Randy Dunlap , Wolfram Sang , Corey Minyard , Rob Herring , Krzysztof Kozlowski , Brendan Higgins , Benjamin Herrenschmidt , Joel Stanley , Andrew Jeffery , openipmi-developer@lists.sourceforge.net, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org, openbmc@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-aspeed@lists.ozlabs.org, Open Source Submission Cc: Phong Vo , thang@os.amperecomputing.com, Quan Nguyen Subject: [PATCH v9 3/3] i2c: aspeed: Assert NAK when slave is busy Date: Thu, 29 Sep 2022 15:03:26 +0700 Message-Id: <20220929080326.752907-4-quan@os.amperecomputing.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220929080326.752907-1-quan@os.amperecomputing.com> References: <20220929080326.752907-1-quan@os.amperecomputing.com> X-ClientProxiedBy: SI2P153CA0002.APCP153.PROD.OUTLOOK.COM (2603:1096:4:140::16) To SJ0PR01MB7282.prod.exchangelabs.com (2603:10b6:a03:3f2::24) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ0PR01MB7282:EE_|LV2PR01MB7885:EE_ X-MS-Office365-Filtering-Correlation-Id: 8d3a2bbf-9b77-43a6-b866-08daa1f12f21 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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But as the backend driver is busy and unable to process any request from Master, issue RxCmdLast for Slave to auto send NACK on next incoming byte. Signed-off-by: Quan Nguyen --- v9: + Update commit message and add comment to explain the effect of issuing RxCmdLast when Slave busy [Quan] v7 -> v8: + None v6: + New introduced in v6 [Quan] drivers/i2c/busses/i2c-aspeed.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c index 185dedfebbac..3d70f1ce6c6a 100644 --- a/drivers/i2c/busses/i2c-aspeed.c +++ b/drivers/i2c/busses/i2c-aspeed.c @@ -244,6 +244,7 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status) u32 command, irq_handled = 0; struct i2c_client *slave = bus->slave; u8 value; + int ret; if (!slave) return 0; @@ -311,7 +312,13 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status) break; case ASPEED_I2C_SLAVE_WRITE_REQUESTED: bus->slave_state = ASPEED_I2C_SLAVE_WRITE_RECEIVED; - i2c_slave_event(slave, I2C_SLAVE_WRITE_REQUESTED, &value); + ret = i2c_slave_event(slave, I2C_SLAVE_WRITE_REQUESTED, &value); + /* + * Slave ACK's on this address phase already but as the backend driver insists it + * is busy, turn on RxCmdLast for Slave to NACK on the next Rx byte. + */ + if (ret == -EBUSY) + writel(ASPEED_I2CD_M_S_RX_CMD_LAST, bus->base + ASPEED_I2C_CMD_REG); break; case ASPEED_I2C_SLAVE_WRITE_RECEIVED: i2c_slave_event(slave, I2C_SLAVE_WRITE_RECEIVED, &value);