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) {
+ 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));
+ 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) {
+ 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))
+ 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;
+ case SSIF_IPMI_MULTIPART_WRITE_START:
+ /* Reset length to zero */
+ if (ssif_bmc->msg_idx == 1)
+ ssif_bmc->request.len = 0;
+
+ fallthrough;
+ case SSIF_IPMI_MULTIPART_WRITE_MIDDLE:
+ case SSIF_IPMI_MULTIPART_WRITE_END:
+ /* 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
