mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-12 13:55:32 +00:00
31c143f712
At the moment, the WWAN core provides wwan_port_txon/off() to implement blocking writes. The tx() port operation should not block, instead wwan_port_txon/off() should be called when the TX queue is full or has free space again. However, in some cases it is not straightforward to make use of that functionality. For example, the RPMSG API used by rpmsg_wwan_ctrl.c does not provide any way to be notified when the TX queue has space again. Instead, it only provides the following operations: - rpmsg_send(): blocking write (wait until there is space) - rpmsg_trysend(): non-blocking write (return error if no space) - rpmsg_poll(): set poll flags depending on TX queue state Generally that's totally sufficient for implementing a char device, but it does not fit well to the currently provided WWAN port ops. Most of the time, using the non-blocking rpmsg_trysend() in the WWAN tx() port operation works just fine. However, with high-frequent writes to the char device it is possible to trigger a situation where this causes issues. For example, consider the following (somewhat unrealistic) example: # dd if=/dev/zero bs=1000 of=/dev/wwan0qmi0 dd: error writing '/dev/wwan0qmi0': Resource temporarily unavailable 1+0 records out This fails immediately after writing the first record. It's likely only a matter of time until this triggers issues for some real application (e.g. ModemManager sending a lot of large QMI packets). The rpmsg_char device does not have this problem, because it uses rpmsg_trysend() and rpmsg_poll() to support non-blocking operations. Make it possible to use the same in the RPMSG WWAN driver by adding two new optional wwan_port_ops: - tx_blocking(): send data blocking if allowed - tx_poll(): set additional TX poll flags This integrates nicely with the RPMSG API and does not require any change in existing WWAN drivers. With these changes, the dd example above blocks instead of exiting with an error. Cc: Loic Poulain <loic.poulain@linaro.org> Signed-off-by: Stephan Gerhold <stephan@gerhold.net> Signed-off-by: David S. Miller <davem@davemloft.net>
152 lines
4.6 KiB
C
152 lines
4.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
|
|
/* Copyright (c) 2021, Linaro Ltd <loic.poulain@linaro.org> */
|
|
|
|
#ifndef __WWAN_H
|
|
#define __WWAN_H
|
|
|
|
#include <linux/device.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/poll.h>
|
|
#include <linux/skbuff.h>
|
|
#include <linux/netlink.h>
|
|
|
|
/**
|
|
* enum wwan_port_type - WWAN port types
|
|
* @WWAN_PORT_AT: AT commands
|
|
* @WWAN_PORT_MBIM: Mobile Broadband Interface Model control
|
|
* @WWAN_PORT_QMI: Qcom modem/MSM interface for modem control
|
|
* @WWAN_PORT_QCDM: Qcom Modem diagnostic interface
|
|
* @WWAN_PORT_FIREHOSE: XML based command protocol
|
|
*
|
|
* @WWAN_PORT_MAX: Highest supported port types
|
|
* @WWAN_PORT_UNKNOWN: Special value to indicate an unknown port type
|
|
* @__WWAN_PORT_MAX: Internal use
|
|
*/
|
|
enum wwan_port_type {
|
|
WWAN_PORT_AT,
|
|
WWAN_PORT_MBIM,
|
|
WWAN_PORT_QMI,
|
|
WWAN_PORT_QCDM,
|
|
WWAN_PORT_FIREHOSE,
|
|
|
|
/* Add new port types above this line */
|
|
|
|
__WWAN_PORT_MAX,
|
|
WWAN_PORT_MAX = __WWAN_PORT_MAX - 1,
|
|
WWAN_PORT_UNKNOWN,
|
|
};
|
|
|
|
struct wwan_port;
|
|
|
|
/** struct wwan_port_ops - The WWAN port operations
|
|
* @start: The routine for starting the WWAN port device.
|
|
* @stop: The routine for stopping the WWAN port device.
|
|
* @tx: Non-blocking routine that sends WWAN port protocol data to the device.
|
|
* @tx_blocking: Optional blocking routine that sends WWAN port protocol data
|
|
* to the device.
|
|
* @tx_poll: Optional routine that sets additional TX poll flags.
|
|
*
|
|
* The wwan_port_ops structure contains a list of low-level operations
|
|
* that control a WWAN port device. All functions are mandatory unless specified.
|
|
*/
|
|
struct wwan_port_ops {
|
|
int (*start)(struct wwan_port *port);
|
|
void (*stop)(struct wwan_port *port);
|
|
int (*tx)(struct wwan_port *port, struct sk_buff *skb);
|
|
|
|
/* Optional operations */
|
|
int (*tx_blocking)(struct wwan_port *port, struct sk_buff *skb);
|
|
__poll_t (*tx_poll)(struct wwan_port *port, struct file *filp,
|
|
poll_table *wait);
|
|
};
|
|
|
|
/**
|
|
* wwan_create_port - Add a new WWAN port
|
|
* @parent: Device to use as parent and shared by all WWAN ports
|
|
* @type: WWAN port type
|
|
* @ops: WWAN port operations
|
|
* @drvdata: Pointer to caller driver data
|
|
*
|
|
* Allocate and register a new WWAN port. The port will be automatically exposed
|
|
* to user as a character device and attached to the right virtual WWAN device,
|
|
* based on the parent pointer. The parent pointer is the device shared by all
|
|
* components of a same WWAN modem (e.g. USB dev, PCI dev, MHI controller...).
|
|
*
|
|
* drvdata will be placed in the WWAN port device driver data and can be
|
|
* retrieved with wwan_port_get_drvdata().
|
|
*
|
|
* This function must be balanced with a call to wwan_remove_port().
|
|
*
|
|
* Returns a valid pointer to wwan_port on success or PTR_ERR on failure
|
|
*/
|
|
struct wwan_port *wwan_create_port(struct device *parent,
|
|
enum wwan_port_type type,
|
|
const struct wwan_port_ops *ops,
|
|
void *drvdata);
|
|
|
|
/**
|
|
* wwan_remove_port - Remove a WWAN port
|
|
* @port: WWAN port to remove
|
|
*
|
|
* Remove a previously created port.
|
|
*/
|
|
void wwan_remove_port(struct wwan_port *port);
|
|
|
|
/**
|
|
* wwan_port_rx - Receive data from the WWAN port
|
|
* @port: WWAN port for which data is received
|
|
* @skb: Pointer to the rx buffer
|
|
*
|
|
* A port driver calls this function upon data reception (MBIM, AT...).
|
|
*/
|
|
void wwan_port_rx(struct wwan_port *port, struct sk_buff *skb);
|
|
|
|
/**
|
|
* wwan_port_txoff - Stop TX on WWAN port
|
|
* @port: WWAN port for which TX must be stopped
|
|
*
|
|
* Used for TX flow control, a port driver calls this function to indicate TX
|
|
* is temporary unavailable (e.g. due to ring buffer fullness).
|
|
*/
|
|
void wwan_port_txoff(struct wwan_port *port);
|
|
|
|
|
|
/**
|
|
* wwan_port_txon - Restart TX on WWAN port
|
|
* @port: WWAN port for which TX must be restarted
|
|
*
|
|
* Used for TX flow control, a port driver calls this function to indicate TX
|
|
* is available again.
|
|
*/
|
|
void wwan_port_txon(struct wwan_port *port);
|
|
|
|
/**
|
|
* wwan_port_get_drvdata - Retrieve driver data from a WWAN port
|
|
* @port: Related WWAN port
|
|
*/
|
|
void *wwan_port_get_drvdata(struct wwan_port *port);
|
|
|
|
/**
|
|
* struct wwan_ops - WWAN device ops
|
|
* @owner: module owner of the WWAN ops
|
|
* @priv_size: size of private netdev data area
|
|
* @setup: set up a new netdev
|
|
* @newlink: register the new netdev
|
|
* @dellink: remove the given netdev
|
|
*/
|
|
struct wwan_ops {
|
|
struct module *owner;
|
|
unsigned int priv_size;
|
|
void (*setup)(struct net_device *dev);
|
|
int (*newlink)(void *ctxt, struct net_device *dev,
|
|
u32 if_id, struct netlink_ext_ack *extack);
|
|
void (*dellink)(void *ctxt, struct net_device *dev,
|
|
struct list_head *head);
|
|
};
|
|
|
|
int wwan_register_ops(struct device *parent, const struct wwan_ops *ops,
|
|
void *ctxt);
|
|
|
|
void wwan_unregister_ops(struct device *parent);
|
|
|
|
#endif /* __WWAN_H */
|