[PATCH v10 1/3] ipmi: ssif_bmc: Add SSIF BMC driver
Quan Nguyen
quan at os.amperecomputing.com
Mon Oct 10 12:28:24 AEDT 2022
On 07/10/2022 20:26, Graeme Gregory wrote:
>
> On 04/10/2022 10:31, Quan Nguyen wrote:
>> The SMBus system interface (SSIF) IPMI BMC driver can be used to perform
>> in-band IPMI communication with their host in management (BMC) side.
>>
>> 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 <quan at os.amperecomputing.com>
>
> I have been testing this on our hardware and I don't seem to be able to
> get this driver working. I was using an older version.
>
> I have hacked ssifbridged to deal with the change in len from u8 to
> unsigned int.
>
> It works as long as I only ever send SSIF commands, any attempt to read
> a response crashes the state machine and the driver never recovers. No
> further SSIF comms is possible! (slave doesnt even ACK writes).
>
> A couple of comments below on possible state machine errors.
>
> Its possible I am doing something wrong!
>
Thanks Graeme for the test and the comments.
What's your testing hardware?
This was tested with Aspeed ast2500 and ast2600 with the patch series
[1] below applied.
If you use the same hw, could you pick the series and see if any thing
improve ?
[1]
https://lore.kernel.org/all/20210616031046.2317-1-quan@os.amperecomputing.com/
>> ---
>> v10:
>> + None
>>
>> 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 <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 |= 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 ||
> Is this actually correct? The state machine seems to set this as the
> default state and in my testing we seem to always reach here with the
> state == SSIF_READY?
The I2C_SLAVE_READ_REQUESTED event is expected to come on SSIF_SMBUS_CMD
state where Slave has already received and validated the SMBus command,
in this case is the I2C_SLAVE_READ_REQUESTED event if the SMBus command
indeed is the READ command. You can see the check supported_read_cmd()
below.
If Slave see the I2C_SLAVE_READ_REQUESTED event on other states, it will
transition to SSIF_ABORTING state that discard everything until there is
a new transaction come.
On READ, the sequence of Slave event should be as below:
I2C_SLAVE_WRITE_REQUESTED (addr) => I2C_SLAVE_WRITE_RECEIVED (SMBus cmd)
=> I2C_SLAVE_READ_REQUESTED (Slave feed the first byte) =>
I2C_SLAVE_READ_PROCESSED (Slave 2nd byte) => .... => I2C_SLAVE_STOP
>> + 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 ||
> Same comment as above?
Same here, I2C_SLAVE_READ_PROCESSED is expected to come after the
I2C_SLAVE_READ_REQUESTED or other I2C_SLAVE_READ_PROCESSED. ie: when the
state is SSIF_RES_SENDING.
If it comes when Slave in states other than SSIF_RES_SENDING, the Slave
will transition to SSIF_ABORTING state.
>> + 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 :
>> + 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 <quan at os.amperecomputing.com>");
>> +MODULE_AUTHOR("Chuong Tran <chuong at os.amperecomputing.com>");
>> +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 <linux/types.h>
>> +
>> +/* 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 */
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