diff options
Diffstat (limited to 'drivers/staging/greybus/raw.c')
-rw-r--r-- | drivers/staging/greybus/raw.c | 381 |
1 files changed, 381 insertions, 0 deletions
diff --git a/drivers/staging/greybus/raw.c b/drivers/staging/greybus/raw.c new file mode 100644 index 0000000..729d258 --- /dev/null +++ b/drivers/staging/greybus/raw.c @@ -0,0 +1,381 @@ +/* + * Greybus driver for the Raw protocol + * + * Copyright 2015 Google Inc. + * Copyright 2015 Linaro Ltd. + * + * Released under the GPLv2 only. + */ +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/sizes.h> +#include <linux/cdev.h> +#include <linux/fs.h> +#include <linux/idr.h> +#include <linux/uaccess.h> + +#include "greybus.h" + +struct gb_raw { + struct gb_connection *connection; + + struct list_head list; + int list_data; + struct mutex list_lock; + dev_t dev; + struct cdev cdev; + struct device *device; +}; + +struct raw_data { + struct list_head entry; + u32 len; + u8 data[0]; +}; + +static struct class *raw_class; +static int raw_major; +static const struct file_operations raw_fops; +static DEFINE_IDA(minors); + +/* Number of minor devices this driver supports */ +#define NUM_MINORS 256 + +/* Maximum size of any one send data buffer we support */ +#define MAX_PACKET_SIZE (PAGE_SIZE * 2) + +/* + * Maximum size of the data in the receive buffer we allow before we start to + * drop messages on the floor + */ +#define MAX_DATA_SIZE (MAX_PACKET_SIZE * 8) + +/* + * Add the raw data message to the list of received messages. + */ +static int receive_data(struct gb_raw *raw, u32 len, u8 *data) +{ + struct raw_data *raw_data; + struct device *dev = &raw->connection->bundle->dev; + int retval = 0; + + if (len > MAX_PACKET_SIZE) { + dev_err(dev, "Too big of a data packet, rejected\n"); + return -EINVAL; + } + + mutex_lock(&raw->list_lock); + if ((raw->list_data + len) > MAX_DATA_SIZE) { + dev_err(dev, "Too much data in receive buffer, now dropping packets\n"); + retval = -EINVAL; + goto exit; + } + + raw_data = kmalloc(sizeof(*raw_data) + len, GFP_KERNEL); + if (!raw_data) { + retval = -ENOMEM; + goto exit; + } + + raw->list_data += len; + raw_data->len = len; + memcpy(&raw_data->data[0], data, len); + + list_add_tail(&raw_data->entry, &raw->list); +exit: + mutex_unlock(&raw->list_lock); + return retval; +} + +static int gb_raw_request_handler(struct gb_operation *op) +{ + struct gb_connection *connection = op->connection; + struct device *dev = &connection->bundle->dev; + struct gb_raw *raw = greybus_get_drvdata(connection->bundle); + struct gb_raw_send_request *receive; + u32 len; + + if (op->type != GB_RAW_TYPE_SEND) { + dev_err(dev, "unknown request type 0x%02x\n", op->type); + return -EINVAL; + } + + /* Verify size of payload */ + if (op->request->payload_size < sizeof(*receive)) { + dev_err(dev, "raw receive request too small (%zu < %zu)\n", + op->request->payload_size, sizeof(*receive)); + return -EINVAL; + } + receive = op->request->payload; + len = le32_to_cpu(receive->len); + if (len != (int)(op->request->payload_size - sizeof(__le32))) { + dev_err(dev, "raw receive request wrong size %d vs %d\n", len, + (int)(op->request->payload_size - sizeof(__le32))); + return -EINVAL; + } + if (len == 0) { + dev_err(dev, "raw receive request of 0 bytes?\n"); + return -EINVAL; + } + + return receive_data(raw, len, receive->data); +} + +static int gb_raw_send(struct gb_raw *raw, u32 len, const char __user *data) +{ + struct gb_connection *connection = raw->connection; + struct gb_raw_send_request *request; + int retval; + + request = kmalloc(len + sizeof(*request), GFP_KERNEL); + if (!request) + return -ENOMEM; + + if (copy_from_user(&request->data[0], data, len)) { + kfree(request); + return -EFAULT; + } + + request->len = cpu_to_le32(len); + + retval = gb_operation_sync(connection, GB_RAW_TYPE_SEND, + request, len + sizeof(*request), + NULL, 0); + + kfree(request); + return retval; +} + +static int gb_raw_probe(struct gb_bundle *bundle, + const struct greybus_bundle_id *id) +{ + struct greybus_descriptor_cport *cport_desc; + struct gb_connection *connection; + struct gb_raw *raw; + int retval; + int minor; + + if (bundle->num_cports != 1) + return -ENODEV; + + cport_desc = &bundle->cport_desc[0]; + if (cport_desc->protocol_id != GREYBUS_PROTOCOL_RAW) + return -ENODEV; + + raw = kzalloc(sizeof(*raw), GFP_KERNEL); + if (!raw) + return -ENOMEM; + + connection = gb_connection_create(bundle, le16_to_cpu(cport_desc->id), + gb_raw_request_handler); + if (IS_ERR(connection)) { + retval = PTR_ERR(connection); + goto error_free; + } + + INIT_LIST_HEAD(&raw->list); + mutex_init(&raw->list_lock); + + raw->connection = connection; + greybus_set_drvdata(bundle, raw); + + minor = ida_simple_get(&minors, 0, 0, GFP_KERNEL); + if (minor < 0) { + retval = minor; + goto error_connection_destroy; + } + + raw->dev = MKDEV(raw_major, minor); + cdev_init(&raw->cdev, &raw_fops); + + retval = gb_connection_enable(connection); + if (retval) + goto error_remove_ida; + + retval = cdev_add(&raw->cdev, raw->dev, 1); + if (retval) + goto error_connection_disable; + + raw->device = device_create(raw_class, &connection->bundle->dev, + raw->dev, raw, "gb!raw%d", minor); + if (IS_ERR(raw->device)) { + retval = PTR_ERR(raw->device); + goto error_del_cdev; + } + + return 0; + +error_del_cdev: + cdev_del(&raw->cdev); + +error_connection_disable: + gb_connection_disable(connection); + +error_remove_ida: + ida_simple_remove(&minors, minor); + +error_connection_destroy: + gb_connection_destroy(connection); + +error_free: + kfree(raw); + return retval; +} + +static void gb_raw_disconnect(struct gb_bundle *bundle) +{ + struct gb_raw *raw = greybus_get_drvdata(bundle); + struct gb_connection *connection = raw->connection; + struct raw_data *raw_data; + struct raw_data *temp; + + // FIXME - handle removing a connection when the char device node is open. + device_destroy(raw_class, raw->dev); + cdev_del(&raw->cdev); + gb_connection_disable(connection); + ida_simple_remove(&minors, MINOR(raw->dev)); + gb_connection_destroy(connection); + + mutex_lock(&raw->list_lock); + list_for_each_entry_safe(raw_data, temp, &raw->list, entry) { + list_del(&raw_data->entry); + kfree(raw_data); + } + mutex_unlock(&raw->list_lock); + + kfree(raw); +} + +/* + * Character device node interfaces. + * + * Note, we are using read/write to only allow a single read/write per message. + * This means for read(), you have to provide a big enough buffer for the full + * message to be copied into. If the buffer isn't big enough, the read() will + * fail with -ENOSPC. + */ + +static int raw_open(struct inode *inode, struct file *file) +{ + struct cdev *cdev = inode->i_cdev; + struct gb_raw *raw = container_of(cdev, struct gb_raw, cdev); + + file->private_data = raw; + return 0; +} + +static ssize_t raw_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + struct gb_raw *raw = file->private_data; + int retval; + + if (!count) + return 0; + + if (count > MAX_PACKET_SIZE) + return -E2BIG; + + retval = gb_raw_send(raw, count, buf); + if (retval) + return retval; + + return count; +} + +static ssize_t raw_read(struct file *file, char __user *buf, size_t count, + loff_t *ppos) +{ + struct gb_raw *raw = file->private_data; + int retval = 0; + struct raw_data *raw_data; + + mutex_lock(&raw->list_lock); + if (list_empty(&raw->list)) + goto exit; + + raw_data = list_first_entry(&raw->list, struct raw_data, entry); + if (raw_data->len > count) { + retval = -ENOSPC; + goto exit; + } + + if (copy_to_user(buf, &raw_data->data[0], raw_data->len)) { + retval = -EFAULT; + goto exit; + } + + list_del(&raw_data->entry); + raw->list_data -= raw_data->len; + retval = raw_data->len; + kfree(raw_data); + +exit: + mutex_unlock(&raw->list_lock); + return retval; +} + +static const struct file_operations raw_fops = { + .owner = THIS_MODULE, + .write = raw_write, + .read = raw_read, + .open = raw_open, + .llseek = noop_llseek, +}; + +static const struct greybus_bundle_id gb_raw_id_table[] = { + { GREYBUS_DEVICE_CLASS(GREYBUS_CLASS_RAW) }, + { } +}; +MODULE_DEVICE_TABLE(greybus, gb_raw_id_table); + +static struct greybus_driver gb_raw_driver = { + .name = "raw", + .probe = gb_raw_probe, + .disconnect = gb_raw_disconnect, + .id_table = gb_raw_id_table, +}; + +static int raw_init(void) +{ + dev_t dev; + int retval; + + raw_class = class_create(THIS_MODULE, "gb_raw"); + if (IS_ERR(raw_class)) { + retval = PTR_ERR(raw_class); + goto error_class; + } + + retval = alloc_chrdev_region(&dev, 0, NUM_MINORS, "gb_raw"); + if (retval < 0) + goto error_chrdev; + + raw_major = MAJOR(dev); + + retval = greybus_register(&gb_raw_driver); + if (retval) + goto error_gb; + + return 0; + +error_gb: + unregister_chrdev_region(dev, NUM_MINORS); +error_chrdev: + class_destroy(raw_class); +error_class: + return retval; +} +module_init(raw_init); + +static void __exit raw_exit(void) +{ + greybus_deregister(&gb_raw_driver); + unregister_chrdev_region(MKDEV(raw_major, 0), NUM_MINORS); + class_destroy(raw_class); + ida_destroy(&minors); +} +module_exit(raw_exit); + +MODULE_LICENSE("GPL v2"); |