Re: [PATCH v3 2/7] ipmi: ssif_bmc: Add SSIF BMC driver
From: Quan Nguyen
Date: Thu May 20 2021 - 10:19:44 EST
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 <quan@xxxxxxxxxxxxxxxxxxxxxx>
---
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 <chuong@xxxxxxxxxxxxxxxxxxxxxx>");
+MODULE_AUTHOR("Quan Nguyen <quan@xxxxxxxxxxxxxxxxxxxxxx>");
+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