by Quan Nguyen

[permalink] [raw]

Subject: Re: [PATCH v3 2/7] ipmi: ssif_bmc: Add SSIF BMC driver

On 19/05/2021 19:30, Corey Minyard wrote:
> On Wed, May 19, 2021 at 02:49:29PM +0700, 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.
>>
>> Signed-off-by: Quan Nguyen <[email protected]>
>> ---
>> 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()/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 | 11 +
>> drivers/char/ipmi/Makefile | 1 +
>> drivers/char/ipmi/ssif_bmc.c | 605 +++++++++++++++++++++++++++++++++++
>> drivers/char/ipmi/ssif_bmc.h | 93 ++++++
>> 4 files changed, 710 insertions(+)
>> create mode 100644 drivers/char/ipmi/ssif_bmc.c
>> create mode 100644 drivers/char/ipmi/ssif_bmc.h
>>
>> diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig
>> index 07847d9a459a..ad5c5161bcd6 100644
>> --- a/drivers/char/ipmi/Kconfig
>> +++ b/drivers/char/ipmi/Kconfig
>> @@ -133,6 +133,17 @@ 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"
>> + select I2C
>> + select 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 0822adc2ec41..d04a214d74c4 100644
>> --- a/drivers/char/ipmi/Makefile
>> +++ b/drivers/char/ipmi/Makefile
>> @@ -27,3 +27,4 @@ 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..d0ea7059b1db
>> --- /dev/null
>> +++ b/drivers/char/ipmi/ssif_bmc.c
>> @@ -0,0 +1,605 @@
>> +// SPDX-License-Identifier: GPL-2.0+
>> +/*
>> + * The driver for BMC side of SSIF interface
>> + *
>> + * Copyright (c) 2021, 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 "ssif_bmc.h"
>> +
>> +/* 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 ssif_msg msg;
>> + unsigned long flags;
>> + ssize_t ret;
>> +
>> + spin_lock_irqsave(&ssif_bmc->lock, flags);
>> + while (!ssif_bmc->request_available) {
>> + if (file->f_flags & O_NONBLOCK) {
>
> There is no real need to check this under the lock. It would simplify
> the end of this function if you checked this outside the lock.
>
Thanks for your reviewing.

Will apply change like below in next version:

spin_lock_irqsave(&ssif_bmc->lock, flags);
while (!ssif_bmc->request_available) {
- if (file->f_flags & O_NONBLOCK) {
- ret = -EAGAIN;
- goto out_unlock;
- }
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)

>> + ret = -EAGAIN;
>> + goto out_unlock;
>> + }
>> + spin_unlock_irqrestore(&ssif_bmc->lock, flags);
>> + ret = wait_event_interruptible(ssif_bmc->wait_queue,
>> + ssif_bmc->request_available);
>> + if (ret)
>> + return ret;
>> + spin_lock_irqsave(&ssif_bmc->lock, flags);
>> + }
>> +
>> + count = min_t(ssize_t, ssif_msg_len(&ssif_bmc->request),
>> + min_t(ssize_t, sizeof(struct ssif_msg), count));
>
> Just curious, what happens if userland supplies a buffer that is too
> small? Is data lost? In that case, I would think returning an error
> here would be the better thing, as opposed to silently truncating the
> message.
>
Will return -EINVAL if buffer is too small in next version

>> + 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);
>> + goto out;
>> +
>> +out_unlock:
>> + spin_unlock_irqrestore(&ssif_bmc->lock, flags);
>> +out:
>> + 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 ssif_msg msg;
>> + unsigned long flags;
>> + ssize_t ret;
>> +
>> + if (count > sizeof(struct ssif_msg))
>> + return -EINVAL;
>> +
>> + ret = copy_from_user(&msg, buf, count);
>> + if (ret)
>> + return ret;
>> +
>> + if (!msg.len || count < ssif_msg_len(&msg))
>> + return -EINVAL;
>> +
>> + spin_lock_irqsave(&ssif_bmc->lock, flags);
>> + while (ssif_bmc->response_in_progress) {
>> + if (file->f_flags & O_NONBLOCK) {
>
> Same comment as O_NONBLOCK before.
>
Will apply this follow the above in ssif_bmc_read()

>> + ret = -EAGAIN;
>> + goto out_unlock;
>> + }
>> + spin_unlock_irqrestore(&ssif_bmc->lock, flags);
>> + ret = wait_event_interruptible(ssif_bmc->wait_queue,
>> + !ssif_bmc->response_in_progress);
>> + if (ret)
>> + goto out;
>> + spin_lock_irqsave(&ssif_bmc->lock, flags);
>> + }
>> +
>> + memcpy(&ssif_bmc->response, &msg, count);
>> + ssif_bmc->is_singlepart_read = (ssif_msg_len(&msg) <= MAX_PAYLOAD_PER_TRANSACTION + 1);
>> + ssif_bmc->response_in_progress = true;
>> + if (ssif_bmc->set_ssif_bmc_status)
>> + ssif_bmc->set_ssif_bmc_status(ssif_bmc, SSIF_BMC_READY);
>> +
>> +out_unlock:
>> + spin_unlock_irqrestore(&ssif_bmc->lock, flags);
>> +
>> +out:
>> + 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 unsigned int ssif_bmc_poll(struct file *file, poll_table *wait)
>> +{
>> + struct ssif_bmc_ctx *ssif_bmc = to_ssif_bmc(file);
>> + unsigned int mask = 0;
>> +
>> + poll_wait(file, &ssif_bmc->wait_queue, wait);
>> +
>> + spin_lock_irq(&ssif_bmc->lock);
>> + /*
>> + * The request message is now available so 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 handle_request(struct ssif_bmc_ctx *ssif_bmc)
>> +{
>> + if (ssif_bmc->set_ssif_bmc_status)
>> + ssif_bmc->set_ssif_bmc_status(ssif_bmc, SSIF_BMC_BUSY);
>> +
>> + /* Request message is available to process */
>> + ssif_bmc->request_available = true;
>> + /*
>> + * This is the new READ request.
>> + */
>> + wake_up_all(&ssif_bmc->wait_queue);
>> +}
>> +
>> +/* 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;
>> + wake_up_all(&ssif_bmc->wait_queue);
>> +}
>> +
>> +static void set_multipart_response_buffer(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
>> +{
>> + u8 response_len = 0;
>> + int idx = 0;
>> + u8 data_len;
>> +
>> + data_len = ssif_bmc->response.len;
>> + switch (ssif_bmc->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.
>> + */
>> + *val = MAX_PAYLOAD_PER_TRANSACTION;
>> + ssif_bmc->remain_len = data_len - MAX_IPMI_DATA_PER_START_TRANSACTION;
>> + ssif_bmc->block_num = 0;
>> +
>> + ssif_bmc->response_buf[idx++] = 0x00; /* Start Flag */
>> + ssif_bmc->response_buf[idx++] = 0x01; /* Start Flag */
>> + ssif_bmc->response_buf[idx++] = ssif_bmc->response.netfn_lun;
>> + ssif_bmc->response_buf[idx++] = ssif_bmc->response.cmd;
>> + ssif_bmc->response_buf[idx++] = ssif_bmc->response.payload[0];
>> +
>> + response_len = MAX_PAYLOAD_PER_TRANSACTION - idx;
>> +
>> + memcpy(&ssif_bmc->response_buf[idx], &ssif_bmc->response.payload[1],
>> + response_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
>> + *
>> + */
>> + *val = ssif_bmc->remain_len + 1;
>> + ssif_bmc->block_num = 0xFF;
>> + ssif_bmc->response_buf[idx++] = ssif_bmc->block_num;
>> + response_len = ssif_bmc->remain_len;
>> + /* Clean the buffer */
>> + memset(&ssif_bmc->response_buf[idx], 0, MAX_PAYLOAD_PER_TRANSACTION - idx);
>> + } 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
>> + */
>> + *val = MAX_PAYLOAD_PER_TRANSACTION;
>> + ssif_bmc->remain_len -= MAX_IPMI_DATA_PER_MIDDLE_TRANSACTION;
>> + response_len = MAX_IPMI_DATA_PER_MIDDLE_TRANSACTION;
>> + ssif_bmc->response_buf[idx++] = ssif_bmc->block_num;
>> + ssif_bmc->block_num++;
>> + }
>> +
>> + memcpy(&ssif_bmc->response_buf[idx],
>> + ssif_bmc->response.payload + 1 + ssif_bmc->nbytes_processed,
>> + response_len);
>> + break;
>> +
>> + default:
>> + /* Do not expect to go to this case */
>> + dev_err(&ssif_bmc->client->dev,
>> + "Error: Unexpected SMBus command received 0x%x\n", ssif_bmc->smbus_cmd);
>> + break;
>> + }
>> +
>> + ssif_bmc->nbytes_processed += response_len;
>> +}
>> +
>> +/* Process the IPMI response that will be read by master */
>> +static void handle_read_processed(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
>> +{
>> + u8 *buf;
>> + u8 pec_len, addr, len;
>> + u8 pec = 0;
>> +
>> + pec_len = ssif_bmc->pec_support ? 1 : 0;
>> + /* PEC - Start Read Address */
>> + addr = GET_8BIT_ADDR(ssif_bmc->client->addr);
>> + pec = i2c_smbus_pec(pec, &addr, 1);
>> + /* PEC - SSIF Command */
>> + pec = i2c_smbus_pec(pec, &ssif_bmc->smbus_cmd, 1);
>> + /* PEC - Restart Write Address */
>> + addr = addr | 0x01;
>> + pec = i2c_smbus_pec(pec, &addr, 1);
>> +
>> + if (ssif_bmc->is_singlepart_read) {
>> + /* Single-part Read processing */
>> + buf = (u8 *)&ssif_bmc->response;
>> +
>> + if (ssif_bmc->response.len && ssif_bmc->msg_idx < ssif_bmc->response.len) {
>> + ssif_bmc->msg_idx++;
>> + *val = buf[ssif_bmc->msg_idx];
>> + } else if (ssif_bmc->response.len && ssif_bmc->msg_idx == ssif_bmc->response.len) {
>> + ssif_bmc->msg_idx++;
>> + *val = i2c_smbus_pec(pec, buf, ssif_msg_len(&ssif_bmc->response));
>> + } else {
>> + *val = 0;
>> + }
>> + /* Invalidate response buffer to denote it is sent */
>> + if (ssif_bmc->msg_idx + 1 >= (ssif_msg_len(&ssif_bmc->response) + pec_len))
>> + complete_response(ssif_bmc);
>> + } else {
>> + /* Multi-part Read processing */
>> + switch (ssif_bmc->smbus_cmd) {
>> + case SSIF_IPMI_MULTIPART_READ_START:
>> + case SSIF_IPMI_MULTIPART_READ_MIDDLE:
>> + buf = (u8 *)&ssif_bmc->response_buf;
>> + *val = buf[ssif_bmc->msg_idx];
>> + ssif_bmc->msg_idx++;
>> + break;
>> + default:
>> + /* Do not expect to go to this case */
>> + dev_err(&ssif_bmc->client->dev,
>> + "Error: Unexpected SMBus command received 0x%x\n",
>> + ssif_bmc->smbus_cmd);
>> + break;
>> + }
>> + len = (ssif_bmc->block_num == 0xFF) ?
>> + ssif_bmc->remain_len + 1 : MAX_PAYLOAD_PER_TRANSACTION;
>> + if (ssif_bmc->msg_idx == (len + 1)) {
>> + pec = i2c_smbus_pec(pec, &len, 1);
>> + *val = i2c_smbus_pec(pec, ssif_bmc->response_buf, len);
>> + }
>> + /* Invalidate response buffer to denote last response is sent */
>> + if (ssif_bmc->block_num == 0xFF &&
>> + ssif_bmc->msg_idx > (ssif_bmc->remain_len + pec_len)) {
>> + complete_response(ssif_bmc);
>> + }
>> + }
>> +}
>> +
>> +static void handle_write_received(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
>> +{
>> + u8 *buf;
>> + u8 smbus_cmd;
>> +
>> + buf = (u8 *)&ssif_bmc->request;
>> + if (ssif_bmc->msg_idx >= sizeof(struct ssif_msg))
>
> Shouldn't you abort the message if you get too much data? Otherwise you
> get silent truncation.
>
Will try to abort bad request in next version.

>> + return;
>> +
>> + smbus_cmd = ssif_bmc->smbus_cmd;
>> + switch (smbus_cmd) {
>> + case SSIF_IPMI_SINGLEPART_WRITE:
>> + /* Single-part write */
>> + buf[ssif_bmc->msg_idx - 1] = *val;
>> + ssif_bmc->msg_idx++;
>> +
>> + break;
>
> Generally you put the space after the break, not before. You did this
> right before, but didn't from here down in the file.
>
Will fix them in next version.

>> + case SSIF_IPMI_MULTIPART_WRITE_START:
>> + /* Reset length to zero */
>> + if (ssif_bmc->msg_idx == 1)
>> + ssif_bmc->request.len = 0;
>
> What happens if you get this and you are in the middle of a message?
>
As per specs, this message should be discarded. This part is still
missing. I'll try to add this feature in next version.

>> +
>> + fallthrough;
>> + case SSIF_IPMI_MULTIPART_WRITE_MIDDLE:
>> + case SSIF_IPMI_MULTIPART_WRITE_END:
>
> What happens if you get these and you are not in a message?
>
Same as my comment above.

>> + /* Multi-part write, 2nd byte received is length */
>> + if (ssif_bmc->msg_idx == 1) {
>> + ssif_bmc->request.len += *val;
>> + ssif_bmc->recv_len = *val;
>> + } else {
>> + buf[ssif_bmc->msg_idx - 1 +
>> + ssif_bmc->request.len - ssif_bmc->recv_len] = *val;
>> + }
>> +
>> + ssif_bmc->msg_idx++;
>> +
>> + break;
>> + default:
>> + /* Do not expect to go to this case */
>> + dev_err(&ssif_bmc->client->dev,
>> + "Error: Unexpected SMBus command received 0x%x\n", ssif_bmc->smbus_cmd);
>> + break;
>> + }
>> +}
>> +
>> +static bool validate_pec(struct ssif_bmc_ctx *ssif_bmc)
>> +{
>> + u8 rpec = 0, cpec = 0;
>> + bool ret = true;
>> + u8 addr, index;
>> + u8 *buf;
>> +
>> + buf = (u8 *)&ssif_bmc->request;
>> + switch (ssif_bmc->smbus_cmd) {
>> + case SSIF_IPMI_SINGLEPART_WRITE:
>> + if ((ssif_bmc->msg_idx - 1) == ssif_msg_len(&ssif_bmc->request)) {
>> + /* PEC is not included */
>> + ssif_bmc->pec_support = false;
>> + return true;
>> + }
>> +
>> + if ((ssif_bmc->msg_idx - 1) != (ssif_msg_len(&ssif_bmc->request) + 1))
>> + goto error;
>> +
>> + /* PEC is included */
>> + ssif_bmc->pec_support = true;
>> + rpec = buf[ssif_bmc->msg_idx - 2];
>> + addr = GET_8BIT_ADDR(ssif_bmc->client->addr);
>> + cpec = i2c_smbus_pec(cpec, &addr, 1);
>> + cpec = i2c_smbus_pec(cpec, &ssif_bmc->smbus_cmd, 1);
>> + cpec = i2c_smbus_pec(cpec, buf, ssif_msg_len(&ssif_bmc->request));
>> + if (rpec != cpec) {
>> + dev_err(&ssif_bmc->client->dev, "Bad PEC 0x%02x vs. 0x%02x\n", rpec, cpec);
>> + ret = false;
>> + }
>> +
>> + break;
>> + case SSIF_IPMI_MULTIPART_WRITE_START:
>> + case SSIF_IPMI_MULTIPART_WRITE_MIDDLE:
>> + case SSIF_IPMI_MULTIPART_WRITE_END:
>> + index = ssif_bmc->request.len - ssif_bmc->recv_len;
>> + if ((ssif_bmc->msg_idx - 1 + index) == ssif_msg_len(&ssif_bmc->request)) {
>> + /* PEC is not included */
>> + ssif_bmc->pec_support = false;
>> + return true;
>> + }
>> +
>> + if ((ssif_bmc->msg_idx - 1 + index) != (ssif_msg_len(&ssif_bmc->request) + 1))
>> + goto error;
>> +
>> + /* PEC is included */
>> + ssif_bmc->pec_support = true;
>> + rpec = buf[ssif_bmc->msg_idx - 2 + index];
>> + addr = GET_8BIT_ADDR(ssif_bmc->client->addr);
>> + cpec = i2c_smbus_pec(cpec, &addr, 1);
>> + cpec = i2c_smbus_pec(cpec, &ssif_bmc->smbus_cmd, 1);
>> + cpec = i2c_smbus_pec(cpec, &ssif_bmc->recv_len, 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-bytes 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 (ssif_bmc->recv_len != 0)
>> + cpec = i2c_smbus_pec(cpec, buf + 1 + index, ssif_bmc->recv_len);
>> +
>> + if (rpec != cpec) {
>> + dev_err(&ssif_bmc->client->dev, "Bad PEC 0x%02x vs. 0x%02x\n", rpec, cpec);
>> + ret = false;
>> + }
>> +
>> + break;
>> + default:
>> + break;
>> + }
>> +
>> + return ret;
>> +error:
>> + /* Do not expect to go to this case */
>> + dev_err(&ssif_bmc->client->dev,
>> + "Error: Unexpected length received %d\n", ssif_msg_len(&ssif_bmc->request));
>> +
>> + return false;
>> +}
>> +
>> +static void complete_write_received(struct ssif_bmc_ctx *ssif_bmc)
>> +{
>> + u8 cmd = ssif_bmc->smbus_cmd;
>> +
>> + /* A BMC that receives an invalid PEC shall 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
>> + */
>> + if (!validate_pec(ssif_bmc)) {
>> + dev_err(&ssif_bmc->client->dev, "Received invalid PEC\n");
>> + return;
>> + }
>> +
>> + if (cmd == SSIF_IPMI_SINGLEPART_WRITE || cmd == SSIF_IPMI_MULTIPART_WRITE_END)
>> + handle_request(ssif_bmc);
>> +}
>> +
>> +static void initialize_transfer(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
>> +{
>> + /* SMBUS command can vary (single or multi-part) */
>> + ssif_bmc->smbus_cmd = *val;
>> + ssif_bmc->msg_idx++;
>> +
>> + if (ssif_bmc->smbus_cmd == SSIF_IPMI_SINGLEPART_WRITE ||
>> + ssif_bmc->smbus_cmd == SSIF_IPMI_MULTIPART_WRITE_START) {
>> + /*
>> + * The response can be delayed in BMC causing host SSIF driver
>> + * to timeout and send a new request once BMC slave is ready.
>> + * In that case check for pending response and clear it
>> + */
>> + if (ssif_bmc->response_in_progress) {
>> + dev_err(&ssif_bmc->client->dev,
>> + "Warn: SSIF new request with pending response");
>> + complete_response(ssif_bmc);
>> + }
>> + } else if (unlikely(ssif_bmc->smbus_cmd != SSIF_IPMI_SINGLEPART_READ &&
>> + ssif_bmc->smbus_cmd != SSIF_IPMI_MULTIPART_WRITE_MIDDLE &&
>> + ssif_bmc->smbus_cmd != SSIF_IPMI_MULTIPART_WRITE_END &&
>> + ssif_bmc->smbus_cmd != SSIF_IPMI_MULTIPART_READ_START &&
>> + ssif_bmc->smbus_cmd != SSIF_IPMI_MULTIPART_READ_MIDDLE)) {
>> + /* Unknown command, clear it */
>> + dev_err(&ssif_bmc->client->dev, "Warn: Unknown SMBus command");
>> + complete_response(ssif_bmc);
>> + }
>> +}
>> +
>> +/*
>> + * 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);
>> +
>> + spin_lock_irqsave(&ssif_bmc->lock, flags);
>> +
>> + /* I2C Event Handler:
>> + * I2C_SLAVE_READ_REQUESTED 0x0
>> + * I2C_SLAVE_WRITE_REQUESTED 0x1
>> + * I2C_SLAVE_READ_PROCESSED 0x2
>> + * I2C_SLAVE_WRITE_RECEIVED 0x3
>> + * I2C_SLAVE_STOP 0x4
>> + */
>> + switch (event) {
>> + case I2C_SLAVE_READ_REQUESTED:
>> + ssif_bmc->msg_idx = 0;
>> + if (ssif_bmc->is_singlepart_read)
>> + *val = ssif_bmc->response.len;
>> + else
>> + set_multipart_response_buffer(ssif_bmc, val);
>> + break;
>> +
>> + case I2C_SLAVE_WRITE_REQUESTED:
>> + ssif_bmc->msg_idx = 0;
>> + break;
>> +
>> + case I2C_SLAVE_READ_PROCESSED:
>> + handle_read_processed(ssif_bmc, val);
>> + break;
>> +
>> + case I2C_SLAVE_WRITE_RECEIVED:
>> + if (ssif_bmc->msg_idx)
>> + handle_write_received(ssif_bmc, val);
>> + else
>> + initialize_transfer(ssif_bmc, val);
>> +
>> + break;
>> +
>> + case I2C_SLAVE_STOP:
>> + if (ssif_bmc->last_event == I2C_SLAVE_WRITE_RECEIVED)
>> + complete_write_received(ssif_bmc);
>> + /* Reset message index */
>> + ssif_bmc->msg_idx = 0;
>> + break;
>> +
>> + default:
>> + break;
>> + }
>> + ssif_bmc->last_event = event;
>> + spin_unlock_irqrestore(&ssif_bmc->lock, flags);
>> +
>> + return 0;
>> +}
>> +
>> +struct ssif_bmc_ctx *ssif_bmc_alloc(struct i2c_client *client, int sizeof_priv)
>> +{
>> + struct ssif_bmc_ctx *ssif_bmc;
>> + int ret;
>> +
>> + ssif_bmc = devm_kzalloc(&client->dev, sizeof(*ssif_bmc) + sizeof_priv, GFP_KERNEL);
>> + if (!ssif_bmc)
>> + return ERR_PTR(-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;
>> +
>> + /* 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)
>> + goto out;
>> +
>> + 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);
>> + goto out;
>> + }
>> +
>> + return ssif_bmc;
>> +
>> +out:
>> + devm_kfree(&client->dev, ssif_bmc);
>> + return ERR_PTR(ret);
>> +}
>> +EXPORT_SYMBOL(ssif_bmc_alloc);
>> +
>> +MODULE_AUTHOR("Chuong Tran <[email protected]>");
>> +MODULE_AUTHOR("Quan Nguyen <[email protected]>");
>> +MODULE_DESCRIPTION("Linux device driver of the BMC IPMI SSIF interface.");
>> +MODULE_LICENSE("GPL v2");
>> diff --git a/drivers/char/ipmi/ssif_bmc.h b/drivers/char/ipmi/ssif_bmc.h
>> new file mode 100644
>> index 000000000000..eab540061f14
>> --- /dev/null
>> +++ b/drivers/char/ipmi/ssif_bmc.h
>> @@ -0,0 +1,93 @@
>> +/* SPDX-License-Identifier: GPL-2.0+ */
>> +/*
>> + * The driver for BMC side of SSIF interface
>> + *
>> + * Copyright (c) 2021, Ampere Computing LLC
>> + *
>> + * This program is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU General Public License as
>> + * published by the Free Software Foundation; either version 2 of
>> + * the License, or (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> + * GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program. If not, see <https://www.gnu.org/licenses/>.
>> + */
>> +#ifndef __SSIF_BMC_H__
>> +#define __SSIF_BMC_H__
>> +
>> +#define DEVICE_NAME "ipmi-ssif-host"
>> +
>> +#define GET_8BIT_ADDR(addr_7bit) (((addr_7bit) << 1) & 0xff)
>> +
>> +#define MSG_PAYLOAD_LEN_MAX 252
>> +
>> +/* A standard SMBus Transaction is limited to 32 data bytes */
>> +#define MAX_PAYLOAD_PER_TRANSACTION 32
>> +
>> +#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
>> +
>> +struct ssif_msg {
>> + u8 len;
>> + u8 netfn_lun;
>> + u8 cmd;
>> + u8 payload[MSG_PAYLOAD_LEN_MAX];
>> +} __packed;
>> +
>> +static inline u32 ssif_msg_len(struct ssif_msg *ssif_msg)
>> +{
>> + return ssif_msg->len + 1;
>> +}
>> +
>> +#define SSIF_BMC_BUSY 0x01
>> +#define SSIF_BMC_READY 0x02
>> +
>> +struct ssif_bmc_ctx {
>> + struct i2c_client *client;
>> + struct miscdevice miscdev;
>> + u8 running;
>> + u8 smbus_cmd;
>> + struct ssif_msg request;
>> + bool request_available;
>> + struct ssif_msg response;
>> + bool response_in_progress;
>> + /* Response buffer for Multi-part Read Transaction */
>> + u8 response_buf[MAX_PAYLOAD_PER_TRANSACTION];
>> + /* 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;
>> + size_t msg_idx;
>> + enum i2c_slave_event last_event;
>> + bool pec_support;
>> + /* spinlock */
>> + spinlock_t lock;
>> + wait_queue_head_t wait_queue;
>> + void (*set_ssif_bmc_status)(struct ssif_bmc_ctx *ssif_bmc, unsigned int flags);
>> + void *priv;
>> +};
>> +
>> +static inline struct ssif_bmc_ctx *to_ssif_bmc(struct file *file)
>> +{
>> + return container_of(file->private_data, struct ssif_bmc_ctx, miscdev);
>> +}
>> +
>> +struct ssif_bmc_ctx *ssif_bmc_alloc(struct i2c_client *client, int sizeof_priv);
>> +
>> +#endif /* __SSIF_BMC_H__ */
>> --
>> 2.28.0
>>

2021-06-25 15:06:32

by Wolfram Sang

[permalink] [raw]

Subject: Re: [PATCH v3 1/7] i2c: i2c-core-smbus: Expose PEC calculate function for generic use

On Wed, May 19, 2021 at 02:49:28PM +0700, Quan Nguyen wrote:
> Expose the PEC calculation i2c_smbus_pec() for generic use.
>
> Signed-off-by: Quan Nguyen <[email protected]>

You are the second one who wanted this exported. I agree it makes sense
for slave drivers. So, I'll skip the required user because two are in
flight. Applied to for-next, thanks!

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