diff options
Diffstat (limited to 'drivers/char/ipmi/ssif_bmc.c')
| -rw-r--r-- | drivers/char/ipmi/ssif_bmc.c | 873 |
1 files changed, 873 insertions, 0 deletions
diff --git a/drivers/char/ipmi/ssif_bmc.c b/drivers/char/ipmi/ssif_bmc.c new file mode 100644 index 000000000000..caee848261e9 --- /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 <linux/i2c.h> +#include <linux/miscdevice.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/poll.h> +#include <linux/sched.h> +#include <linux/mutex.h> +#include <linux/spinlock.h> +#include <linux/timer.h> +#include <linux/jiffies.h> +#include <linux/ipmi_ssif_bmc.h> + +#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 |= EPOLLIN; + + 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) +{ + 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_new = ssif_bmc_probe, + .remove = ssif_bmc_remove, + .id_table = ssif_bmc_id, +}; + +module_i2c_driver(ssif_bmc_driver); + +MODULE_AUTHOR("Quan Nguyen <quan@os.amperecomputing.com>"); +MODULE_AUTHOR("Chuong Tran <chuong@os.amperecomputing.com>"); +MODULE_DESCRIPTION("Linux device driver of the BMC IPMI SSIF interface."); +MODULE_LICENSE("GPL"); |