[PATCH v2 3/4] ipmi: bt-i2c: added IPMI Block Transfer over I2C BMC side
Brendan Higgins
brendanhiggins at google.com
Sat Aug 5 11:18:54 AEST 2017
The IPMI definition of the Block Transfer protocol defines the hardware
registers and behavior in addition to the message format and messaging
semantics. This implements a new protocol that uses IPMI Block Transfer
messages and semantics on top of a standard I2C interface. This protocol
has the same BMC side file system interface as "ipmi-bt-host".
Signed-off-by: Brendan Higgins <brendanhiggins at google.com>
---
Changes for v2:
- None
---
drivers/char/Kconfig | 1 +
drivers/char/Makefile | 1 +
drivers/char/ipmi_bmc/Kconfig | 22 ++
drivers/char/ipmi_bmc/Makefile | 5 +
drivers/char/ipmi_bmc/ipmi_bmc_bt_i2c.c | 346 ++++++++++++++++++++++++++++++++
include/linux/ipmi_bmc.h | 76 +++++++
6 files changed, 451 insertions(+)
create mode 100644 drivers/char/ipmi_bmc/Kconfig
create mode 100644 drivers/char/ipmi_bmc/Makefile
create mode 100644 drivers/char/ipmi_bmc/ipmi_bmc_bt_i2c.c
create mode 100644 include/linux/ipmi_bmc.h
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index ccd239ab879f..2a6ca2325a45 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -195,6 +195,7 @@ config POWERNV_OP_PANEL
If unsure, say M here to build it as a module called powernv-op-panel.
source "drivers/char/ipmi/Kconfig"
+source "drivers/char/ipmi_bmc/Kconfig"
config DS1620
tristate "NetWinder thermometer support"
diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index 53e33720818c..9e143186fa30 100644
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -58,4 +58,5 @@ js-rtc-y = rtc.o
obj-$(CONFIG_TILE_SROM) += tile-srom.o
obj-$(CONFIG_XILLYBUS) += xillybus/
+obj-$(CONFIG_IPMI_BMC) += ipmi_bmc/
obj-$(CONFIG_POWERNV_OP_PANEL) += powernv-op-panel.o
diff --git a/drivers/char/ipmi_bmc/Kconfig b/drivers/char/ipmi_bmc/Kconfig
new file mode 100644
index 000000000000..26c8e0cb765c
--- /dev/null
+++ b/drivers/char/ipmi_bmc/Kconfig
@@ -0,0 +1,22 @@
+#
+# IPMI BMC configuration
+#
+
+menuconfig IPMI_BMC
+ tristate 'IPMI BMC core'
+ help
+ This enables the BMC-side IPMI drivers.
+
+ If unsure, say N.
+
+if IPMI_BMC
+
+config IPMI_BMC_BT_I2C
+ depends on I2C
+ select I2C_SLAVE
+ tristate 'Generic I2C BT IPMI BMC driver'
+ help
+ Provides a driver that uses IPMI Block Transfer messages and
+ semantics on top of plain old I2C.
+
+endif # IPMI_BMC
diff --git a/drivers/char/ipmi_bmc/Makefile b/drivers/char/ipmi_bmc/Makefile
new file mode 100644
index 000000000000..dfe5128f8158
--- /dev/null
+++ b/drivers/char/ipmi_bmc/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile for the ipmi bmc drivers.
+#
+
+obj-$(CONFIG_IPMI_BMC_BT_I2C) += ipmi_bmc_bt_i2c.o
diff --git a/drivers/char/ipmi_bmc/ipmi_bmc_bt_i2c.c b/drivers/char/ipmi_bmc/ipmi_bmc_bt_i2c.c
new file mode 100644
index 000000000000..686b83fa42a4
--- /dev/null
+++ b/drivers/char/ipmi_bmc/ipmi_bmc_bt_i2c.c
@@ -0,0 +1,346 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * 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.
+ */
+
+#include <linux/errno.h>
+#include <linux/i2c.h>
+#include <linux/ipmi_bmc.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/wait.h>
+
+#define PFX "IPMI BMC BT-I2C: "
+
+/*
+ * TODO: This is "bt-host" to match the bt-host driver; however, I think this is
+ * unclear in the context of a CPU side driver. Should probably name this
+ * and the DEVICE_NAME in bt-host to something like "bt-bmc" or "bt-slave".
+ */
+#define DEVICE_NAME "ipmi-bt-host"
+
+static const unsigned long request_queue_max_len = 256;
+
+struct bt_request_elem {
+ struct list_head list;
+ struct bt_msg request;
+};
+
+struct bt_i2c_slave {
+ struct i2c_client *client;
+ struct miscdevice miscdev;
+ struct bt_msg request;
+ struct list_head request_queue;
+ atomic_t request_queue_len;
+ struct bt_msg response;
+ bool response_in_progress;
+ size_t msg_idx;
+ spinlock_t lock;
+ wait_queue_head_t wait_queue;
+ struct mutex file_mutex;
+};
+
+static int receive_bt_request(struct bt_i2c_slave *bt_slave, bool non_blocking,
+ struct bt_msg *bt_request)
+{
+ int res;
+ unsigned long flags;
+ struct bt_request_elem *queue_elem;
+
+ if (!non_blocking) {
+try_again:
+ res = wait_event_interruptible(
+ bt_slave->wait_queue,
+ atomic_read(&bt_slave->request_queue_len));
+ if (res)
+ return res;
+ }
+
+ spin_lock_irqsave(&bt_slave->lock, flags);
+ if (!atomic_read(&bt_slave->request_queue_len)) {
+ spin_unlock_irqrestore(&bt_slave->lock, flags);
+ if (non_blocking)
+ return -EAGAIN;
+ goto try_again;
+ }
+
+ if (list_empty(&bt_slave->request_queue)) {
+ pr_err(PFX "request_queue was empty despite nonzero request_queue_len\n");
+ return -EIO;
+ }
+ queue_elem = list_first_entry(&bt_slave->request_queue,
+ struct bt_request_elem, list);
+ memcpy(bt_request, &queue_elem->request, sizeof(*bt_request));
+ list_del(&queue_elem->list);
+ kfree(queue_elem);
+ atomic_dec(&bt_slave->request_queue_len);
+ spin_unlock_irqrestore(&bt_slave->lock, flags);
+ return 0;
+}
+
+static int send_bt_response(struct bt_i2c_slave *bt_slave, bool non_blocking,
+ struct bt_msg *bt_response)
+{
+ int res;
+ unsigned long flags;
+
+ if (!non_blocking) {
+try_again:
+ res = wait_event_interruptible(bt_slave->wait_queue,
+ !bt_slave->response_in_progress);
+ if (res)
+ return res;
+ }
+
+ spin_lock_irqsave(&bt_slave->lock, flags);
+ if (bt_slave->response_in_progress) {
+ spin_unlock_irqrestore(&bt_slave->lock, flags);
+ if (non_blocking)
+ return -EAGAIN;
+ goto try_again;
+ }
+
+ memcpy(&bt_slave->response, bt_response, sizeof(*bt_response));
+ bt_slave->response_in_progress = true;
+ spin_unlock_irqrestore(&bt_slave->lock, flags);
+ return 0;
+}
+
+static inline struct bt_i2c_slave *to_bt_i2c_slave(struct file *file)
+{
+ return container_of(file->private_data, struct bt_i2c_slave, miscdev);
+}
+
+static ssize_t bt_read(struct file *file, char __user *buf, size_t count,
+ loff_t *ppos)
+{
+ struct bt_i2c_slave *bt_slave = to_bt_i2c_slave(file);
+ struct bt_msg msg;
+ ssize_t ret;
+
+ mutex_lock(&bt_slave->file_mutex);
+ ret = receive_bt_request(bt_slave, file->f_flags & O_NONBLOCK, &msg);
+ if (ret < 0)
+ goto out;
+ count = min_t(size_t, count, bt_msg_len(&msg));
+ if (copy_to_user(buf, &msg, count)) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+out:
+ mutex_unlock(&bt_slave->file_mutex);
+ if (ret < 0)
+ return ret;
+ else
+ return count;
+}
+
+static ssize_t bt_write(struct file *file, const char __user *buf, size_t count,
+ loff_t *ppos)
+{
+ struct bt_i2c_slave *bt_slave = to_bt_i2c_slave(file);
+ struct bt_msg msg;
+ ssize_t ret;
+
+ if (count > sizeof(msg))
+ return -EINVAL;
+
+ if (copy_from_user(&msg, buf, count) || count < bt_msg_len(&msg))
+ return -EINVAL;
+
+ mutex_lock(&bt_slave->file_mutex);
+ ret = send_bt_response(bt_slave, file->f_flags & O_NONBLOCK, &msg);
+ mutex_unlock(&bt_slave->file_mutex);
+
+ if (ret < 0)
+ return ret;
+ else
+ return count;
+}
+
+static unsigned int bt_poll(struct file *file, poll_table *wait)
+{
+ struct bt_i2c_slave *bt_slave = to_bt_i2c_slave(file);
+ unsigned int mask = 0;
+
+ mutex_lock(&bt_slave->file_mutex);
+ poll_wait(file, &bt_slave->wait_queue, wait);
+
+ if (atomic_read(&bt_slave->request_queue_len))
+ mask |= POLLIN;
+ if (!bt_slave->response_in_progress)
+ mask |= POLLOUT;
+ mutex_unlock(&bt_slave->file_mutex);
+ return mask;
+}
+
+static const struct file_operations bt_fops = {
+ .owner = THIS_MODULE,
+ .read = bt_read,
+ .write = bt_write,
+ .poll = bt_poll,
+};
+
+/* Called with bt_slave->lock held. */
+static int handle_request(struct bt_i2c_slave *bt_slave)
+{
+ struct bt_request_elem *queue_elem;
+
+ if (atomic_read(&bt_slave->request_queue_len) >= request_queue_max_len)
+ return -EFAULT;
+ queue_elem = kmalloc(sizeof(*queue_elem), GFP_KERNEL);
+ if (!queue_elem)
+ return -ENOMEM;
+ memcpy(&queue_elem->request, &bt_slave->request, sizeof(struct bt_msg));
+ list_add(&queue_elem->list, &bt_slave->request_queue);
+ atomic_inc(&bt_slave->request_queue_len);
+ wake_up_all(&bt_slave->wait_queue);
+ return 0;
+}
+
+/* Called with bt_slave->lock held. */
+static int complete_response(struct bt_i2c_slave *bt_slave)
+{
+ /* Invalidate response in buffer to denote it having been sent. */
+ bt_slave->response.len = 0;
+ bt_slave->response_in_progress = false;
+ wake_up_all(&bt_slave->wait_queue);
+ return 0;
+}
+
+static int bt_i2c_slave_cb(struct i2c_client *client,
+ enum i2c_slave_event event, u8 *val)
+{
+ struct bt_i2c_slave *bt_slave = i2c_get_clientdata(client);
+ u8 *buf;
+
+ spin_lock(&bt_slave->lock);
+ switch (event) {
+ case I2C_SLAVE_WRITE_REQUESTED:
+ bt_slave->msg_idx = 0;
+ break;
+
+ case I2C_SLAVE_WRITE_RECEIVED:
+ buf = (u8 *) &bt_slave->request;
+ if (bt_slave->msg_idx >= sizeof(struct bt_msg))
+ break;
+
+ buf[bt_slave->msg_idx++] = *val;
+ if (bt_slave->msg_idx >= bt_msg_len(&bt_slave->request))
+ handle_request(bt_slave);
+ break;
+
+ case I2C_SLAVE_READ_REQUESTED:
+ buf = (u8 *) &bt_slave->response;
+ bt_slave->msg_idx = 0;
+ *val = buf[bt_slave->msg_idx];
+ /*
+ * Do not increment buffer_idx here, because we don't know if
+ * this byte will be actually used. Read Linux I2C slave docs
+ * for details.
+ */
+ break;
+
+ case I2C_SLAVE_READ_PROCESSED:
+ buf = (u8 *) &bt_slave->response;
+ if (bt_slave->response.len &&
+ bt_slave->msg_idx < bt_msg_len(&bt_slave->response)) {
+ *val = buf[++bt_slave->msg_idx];
+ } else {
+ *val = 0;
+ }
+ if (bt_slave->msg_idx + 1 >= bt_msg_len(&bt_slave->response))
+ complete_response(bt_slave);
+ break;
+
+ case I2C_SLAVE_STOP:
+ bt_slave->msg_idx = 0;
+ break;
+
+ default:
+ break;
+ }
+ spin_unlock(&bt_slave->lock);
+
+ return 0;
+}
+
+static int bt_i2c_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct bt_i2c_slave *bt_slave;
+ int ret;
+
+ bt_slave = devm_kzalloc(&client->dev, sizeof(*bt_slave),
+ GFP_KERNEL);
+ if (!bt_slave)
+ return -ENOMEM;
+
+ spin_lock_init(&bt_slave->lock);
+ init_waitqueue_head(&bt_slave->wait_queue);
+ atomic_set(&bt_slave->request_queue_len, 0);
+ bt_slave->response_in_progress = false;
+ INIT_LIST_HEAD(&bt_slave->request_queue);
+
+ mutex_init(&bt_slave->file_mutex);
+
+ bt_slave->miscdev.minor = MISC_DYNAMIC_MINOR;
+ bt_slave->miscdev.name = DEVICE_NAME;
+ bt_slave->miscdev.fops = &bt_fops;
+ bt_slave->miscdev.parent = &client->dev;
+ ret = misc_register(&bt_slave->miscdev);
+ if (ret)
+ return ret;
+
+ bt_slave->client = client;
+ i2c_set_clientdata(client, bt_slave);
+ ret = i2c_slave_register(client, bt_i2c_slave_cb);
+ if (ret) {
+ misc_deregister(&bt_slave->miscdev);
+ return ret;
+ }
+
+ return 0;
+}
+
+static int bt_i2c_remove(struct i2c_client *client)
+{
+ struct bt_i2c_slave *bt_slave = i2c_get_clientdata(client);
+
+ i2c_slave_unregister(client);
+ misc_deregister(&bt_slave->miscdev);
+ return 0;
+}
+
+static const struct i2c_device_id bt_i2c_id[] = {
+ {"ipmi-bmc-bt-i2c", 0},
+ {},
+};
+MODULE_DEVICE_TABLE(i2c, bt_i2c_id);
+
+static struct i2c_driver bt_i2c_driver = {
+ .driver = {
+ .name = "ipmi-bmc-bt-i2c",
+ },
+ .probe = bt_i2c_probe,
+ .remove = bt_i2c_remove,
+ .id_table = bt_i2c_id,
+};
+module_i2c_driver(bt_i2c_driver);
+
+MODULE_AUTHOR("Brendan Higgins <brendanhiggins at google.com>");
+MODULE_DESCRIPTION("BMC-side IPMI Block Transfer over I2C.");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/ipmi_bmc.h b/include/linux/ipmi_bmc.h
new file mode 100644
index 000000000000..d0885c0bf190
--- /dev/null
+++ b/include/linux/ipmi_bmc.h
@@ -0,0 +1,76 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * 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.
+ */
+
+#ifndef __LINUX_IPMI_BMC_H
+#define __LINUX_IPMI_BMC_H
+
+#include <linux/bug.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/types.h>
+
+#define BT_MSG_PAYLOAD_LEN_MAX 252
+
+/**
+ * struct bt_msg - Block Transfer IPMI message.
+ * @len: Length of the message, not including this field.
+ * @netfn_lun: 6-bit netfn field definining the category of message and 2-bit
+ * lun field used for routing.
+ * @seq: Sequence number used to associate requests with responses.
+ * @cmd: Command within a netfn category.
+ * @payload: Variable length field. May have specific requirements based on
+ * netfn/cmd pair.
+ *
+ * Use bt_msg_len() to determine the total length of a message (including
+ * the @len field) rather than reading it directly.
+ */
+struct bt_msg {
+ u8 len;
+ u8 netfn_lun;
+ u8 seq;
+ u8 cmd;
+ u8 payload[BT_MSG_PAYLOAD_LEN_MAX];
+} __packed;
+
+/**
+ * bt_msg_len() - Determine the total length of a Block Transfer message.
+ * @bt_msg: Pointer to the message.
+ *
+ * This function calculates the length of an IPMI Block Transfer message
+ * including the length field itself.
+ *
+ * Return: Length of @bt_msg.
+ */
+static inline u32 bt_msg_len(struct bt_msg *bt_msg)
+{
+ return bt_msg->len + 1;
+}
+
+/**
+ * bt_msg_payload_to_len() - Calculate the len field of a Block Transfer message
+ * given the length of the payload.
+ * @payload_len: Length of the payload.
+ *
+ * Return: len field of the Block Transfer message which contains this payload.
+ */
+static inline u8 bt_msg_payload_to_len(u8 payload_len)
+{
+ if (unlikely(payload_len > BT_MSG_PAYLOAD_LEN_MAX)) {
+ payload_len = BT_MSG_PAYLOAD_LEN_MAX;
+ WARN(1, "BT message payload is too large. Truncating to %u.\n",
+ BT_MSG_PAYLOAD_LEN_MAX);
+ }
+ return payload_len + 3;
+}
+
+#endif /* __LINUX_IPMI_BMC_H */
--
2.14.0.rc1.383.gd1ce394fe2-goog
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