[RFC 1/2] misc: bt: added IPMI Block Transfer over I2C master and slave
Brendan Higgins
brendanhiggins at google.com
Fri Sep 9 07:28:49 AEST 2016
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 "bt-host".
Signed-off-by: Brendan Higgins <brendanhiggins at google.com>
---
drivers/misc/Kconfig | 23 ++++
drivers/misc/Makefile | 2 +
drivers/misc/bt-i2c-master.c | 199 +++++++++++++++++++++++++++
drivers/misc/bt-i2c-slave.c | 317 +++++++++++++++++++++++++++++++++++++++++++
drivers/misc/bt.h | 19 +++
5 files changed, 560 insertions(+)
create mode 100644 drivers/misc/bt-i2c-master.c
create mode 100644 drivers/misc/bt-i2c-slave.c
create mode 100644 drivers/misc/bt.h
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 4617ddc..1c7e3a9 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -809,6 +809,29 @@ config ASPEED_BT_IPMI_HOST
help
Support for the Aspeed BT ipmi host.
+config BT_I2C_SLAVE
+ depends on !ASPEED_BT_IPMI_HOST && I2C_SLAVE
+ tristate "BT I2C IPMI slave driver"
+ default "n"
+ ---help---
+ Block Transfer over I2C defines a new IPMI compatible interface that
+ uses Block Transfer messages and semantics on top of plain old I2C.
+
+ This adds support for the slave side of the protocol (only really
+ useful for BMCs (Baseboard Management Controllers)).
+
+config BT_I2C_MASTER
+ depends on I2C
+ tristate "BT I2C IPMI master driver"
+ default "n"
+ ---help---
+ Block Transfer over I2C defines a new IPMI compatible interface that
+ uses Block Transfer messages and semantics on top of plain old I2C.
+
+ This adds support for master side of the protocol (this is most likely
+ what you want if you are compiling for a regular CPU, only useful if
+ your computer has a BMC that speaks the slave side of this protocol).
+
source "drivers/misc/c2port/Kconfig"
source "drivers/misc/eeprom/Kconfig"
source "drivers/misc/cb710/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 724861b..b642ed8 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -58,3 +58,5 @@ obj-$(CONFIG_VEXPRESS_SYSCFG) += vexpress-syscfg.o
obj-$(CONFIG_CXL_BASE) += cxl/
obj-$(CONFIG_PANEL) += panel.o
obj-$(CONFIG_ASPEED_BT_IPMI_HOST) += bt-host.o
+obj-$(CONFIG_BT_I2C_SLAVE) += bt-i2c-slave.o
+obj-$(CONFIG_BT_I2C_MASTER) += bt-i2c-master.o
diff --git a/drivers/misc/bt-i2c-master.c b/drivers/misc/bt-i2c-master.c
new file mode 100644
index 0000000..22142d6
--- /dev/null
+++ b/drivers/misc/bt-i2c-master.c
@@ -0,0 +1,199 @@
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/errno.h>
+#include <linux/poll.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/miscdevice.h>
+#include <linux/timer.h>
+#include <linux/jiffies.h>
+
+#include "bt.h"
+
+#define DEVICE_NAME "bt-master"
+
+struct bt_i2c_master {
+ struct i2c_client *client;
+ struct miscdevice miscdev;
+ struct mutex file_mutex;
+};
+
+static const unsigned long write_timeout = 25;
+
+static int send_bt_request(struct bt_i2c_master *bt_master,
+ struct bt_msg *bt_request)
+{
+ struct i2c_client *client = bt_master->client;
+ u8 *buf = (u8 *) bt_request;
+ unsigned long timeout, read_time;
+ int ret;
+
+ timeout = jiffies + msecs_to_jiffies(write_timeout);
+ do {
+ read_time = jiffies;
+ ret = i2c_master_send(client, buf, bt_msg_len(bt_request));
+ if (ret >= 0)
+ return 0;
+ usleep_range(1000, 1500);
+ } while (time_before(read_time, timeout));
+ return ret;
+}
+
+static int receive_bt_response(struct bt_i2c_master *bt_master,
+ struct bt_msg *bt_response)
+{
+ struct i2c_client *client = bt_master->client;
+ u8 *buf = (u8 *) bt_response;
+ u8 len = 0;
+ unsigned long timeout, read_time;
+ int ret;
+
+ /*
+ * Slave may not NACK when not ready, so we peek at the first byte to
+ * see if it is a valid length.
+ */
+ while (len == 0) {
+ i2c_master_recv(client, &len, 1);
+ if (len != 0)
+ break;
+ usleep_range(1000, 1500);
+
+ /* Signal received: quit syscall. */
+ if (signal_pending(current))
+ return -ERESTARTSYS;
+ }
+
+ timeout = jiffies + msecs_to_jiffies(write_timeout);
+ do {
+ read_time = jiffies;
+ ret = i2c_master_recv(client, buf, len + 1);
+ if (ret >= 0)
+ return 0;
+ usleep_range(1000, 1500);
+ } while (time_before(read_time, timeout));
+ return ret;
+}
+
+static inline struct bt_i2c_master *to_bt_i2c_master(struct file *file)
+{
+ return container_of(file->private_data, struct bt_i2c_master, miscdev);
+}
+
+static ssize_t bt_read(struct file *file, char __user *buf, size_t count,
+ loff_t *ppos)
+{
+ struct bt_i2c_master *bt_master = to_bt_i2c_master(file);
+ struct bt_msg msg;
+ int ret;
+
+ mutex_lock(&bt_master->file_mutex);
+ ret = receive_bt_response(bt_master, &msg);
+ if (ret < 0)
+ goto out;
+ count = min(count, bt_msg_len(&msg));
+ if (copy_to_user(buf, &msg, count)) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+out:
+ mutex_unlock(&bt_master->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_master *bt_master = to_bt_i2c_master(file);
+ struct bt_msg msg;
+ int ret;
+
+ mutex_lock(&bt_master->file_mutex);
+ if (count > sizeof(struct bt_msg)) {
+ ret = -EFAULT;
+ goto out;
+ }
+ if (copy_from_user(&msg, buf, count) || count < bt_msg_len(&msg)) {
+ ret = -EFAULT;
+ goto out;
+ }
+ ret = send_bt_request(bt_master, &msg);
+ if (ret < 0)
+ goto out;
+
+out:
+ mutex_unlock(&bt_master->file_mutex);
+ if (ret < 0)
+ return ret;
+ else
+ return count;
+}
+
+static const struct file_operations bt_fops = {
+ .owner = THIS_MODULE,
+ .read = bt_read,
+ .write = bt_write,
+};
+
+static int bt_i2c_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct bt_i2c_master *bt_master;
+ int ret;
+
+ bt_master = devm_kzalloc(&client->dev, sizeof(struct bt_i2c_master),
+ GFP_KERNEL);
+ if (!bt_master)
+ return -ENOMEM;
+
+ mutex_init(&bt_master->file_mutex);
+ bt_master->client = client;
+ i2c_set_clientdata(client, bt_master);
+
+ bt_master->miscdev.minor = MISC_DYNAMIC_MINOR;
+ bt_master->miscdev.name = DEVICE_NAME;
+ bt_master->miscdev.fops = &bt_fops;
+ bt_master->miscdev.parent = &client->dev;
+ ret = misc_register(&bt_master->miscdev);
+ if (ret < 0)
+ return ret;
+ return 0;
+}
+
+static int bt_i2c_remove(struct i2c_client *client)
+{
+ struct bt_i2c_master *bt_master = i2c_get_clientdata(client);
+
+ misc_deregister(&bt_master->miscdev);
+ return 0;
+}
+
+static const struct i2c_device_id bt_i2c_id[] = {
+ {"bt-i2c-master", 0},
+ {},
+};
+MODULE_DEVICE_TABLE(i2c, bt_i2c_id);
+
+static struct i2c_driver bt_i2c_driver = {
+ .driver = {
+ .name = "bt-i2c-master",
+ },
+ .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("IPMI Block Transfer over I2C master.");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/misc/bt-i2c-slave.c b/drivers/misc/bt-i2c-slave.c
new file mode 100644
index 0000000..1a90e05
--- /dev/null
+++ b/drivers/misc/bt-i2c-slave.c
@@ -0,0 +1,317 @@
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/errno.h>
+#include <linux/poll.h>
+#include <linux/spinlock.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/miscdevice.h>
+#include <linux/timer.h>
+#include <linux/jiffies.h>
+
+#include "bt.h"
+
+/*
+ * 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 "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;
+ atomic_t 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) {
+ unsigned long flags;
+ struct bt_request_elem *queue_elem;
+
+ if (!atomic_read(&bt_slave->request_queue_len) && non_blocking)
+ return -EAGAIN;
+ else if (!non_blocking)
+ wait_event_interruptible(
+ bt_slave->wait_queue,
+ atomic_read(&bt_slave->request_queue_len));
+
+ spin_lock_irqsave(&bt_slave->lock, flags);
+ queue_elem = list_first_entry(&bt_slave->request_queue,
+ struct bt_request_elem, list);
+ memcpy(bt_request, &queue_elem->request, sizeof(struct bt_msg));
+ 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) {
+ unsigned long flags;
+
+ if (non_blocking && atomic_read(&bt_slave->response_in_progress))
+ return -EAGAIN;
+ else if (!non_blocking)
+ wait_event_interruptible(
+ bt_slave->wait_queue,
+ !atomic_read(&bt_slave->response_in_progress));
+
+ spin_lock_irqsave(&bt_slave->lock, flags);
+ memcpy(&bt_slave->response, bt_response, sizeof(struct bt_msg));
+ atomic_set(&bt_slave->response_in_progress, 0);
+ 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(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(struct bt_msg))
+ return -EFAULT;
+
+ if (copy_from_user(&msg, buf, count) || count < bt_msg_len(&msg))
+ return -EFAULT;
+
+ 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 long bt_ioctl(struct file *file, unsigned int cmd, unsigned long param)
+{
+ return 0;
+}
+
+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 (!atomic_read(&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,
+ .unlocked_ioctl = bt_ioctl,
+};
+
+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(struct bt_request_elem), GFP_KERNEL);
+ 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;
+}
+
+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;
+ atomic_set(&bt_slave->response_in_progress, 1);
+ 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_i2c_slave))
+ 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(struct bt_i2c_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);
+ atomic_set(&bt_slave->response_in_progress, 0);
+ 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 < 0)
+ return ret;
+
+ bt_slave->client = client;
+ i2c_set_clientdata(client, bt_slave);
+ ret = i2c_slave_register(client, bt_i2c_slave_cb);
+ if (ret < 0) {
+ 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[] = {
+ {"bt-i2c-slave", 0},
+ {},
+};
+MODULE_DEVICE_TABLE(i2c, bt_i2c_id);
+
+static struct i2c_driver bt_i2c_driver = {
+ .driver = {
+ .name = "bt-i2c-slave",
+ },
+ .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("IPMI Block Transfer over I2C slave.");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/misc/bt.h b/drivers/misc/bt.h
new file mode 100644
index 0000000..c0c2881
--- /dev/null
+++ b/drivers/misc/bt.h
@@ -0,0 +1,19 @@
+#ifndef _DRIVERS_MISC_BT_H
+#define _DRIVERS_MISC_BT_H
+
+#include <linux/types.h>
+
+struct bt_msg {
+ u8 len;
+ u8 netfn_lun;
+ u8 seq;
+ u8 cmd;
+ u8 payload[252];
+};
+
+static inline u32 bt_msg_len(struct bt_msg *bt_request)
+{
+ return bt_request->len + 1;
+}
+
+#endif /* _DRIVERS_MISC_BT_H */
--
2.8.0.rc3.226.g39d4020
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