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tty: n_gsm: add ioctl for DLC specific parameter configuration 

Parameter negotiation has been introduced with
commit 92f1f0c329 ("tty: n_gsm: add parameter negotiation support")

However, means to set individual parameters per DLCI are not yet
implemented. Furthermore, it is currently not possible to keep a DLCI half
open until the user application sets the right parameters for it. This is
required to allow a user application to set its specific parameters before
the underlying link is established. Otherwise, the link is opened and
re-established right afterwards if the user application sets incompatible
parameters. This may be an unexpected behavior for the peer.

Add parameter 'wait_config' to 'gsm_config' to support setups where the
DLCI specific user application sets its specific parameters after open()
and before the link gets fully established. Setting this to zero disables
the user application specific DLCI configuration option.

Add the ioctls 'GSMIOC_GETCONF_DLCI' and 'GSMIOC_SETCONF_DLCI' for the
ldisc and virtual ttys. This gets/sets the DLCI specific parameters and may
trigger a reconnect of the DLCI if incompatible values have been set. Only
the parameters for the DLCI associated with the virtual tty can be set or
retrieved if called on these.

Add remark within the documentation to introduce the new ioctls.

Link: https://lore.kernel.org/oe-kbuild-all/202302281856.S9Lz4gHB-lkp@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20230315105354.6234-1-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Daniel Starke 2023-03-15 11:53:52 +01:00 committed by Greg Kroah-Hartman
parent cb95de8d43
commit 4ca589661d
3 changed files with 207 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
Documentation/driver-api/tty/n_gsm.rst
View File

@ -29,6 +29,8 @@ Config Initiator
#. Configure the mux using ``GSMIOC_GETCONF``/``GSMIOC_SETCONF`` ioctl.
#. Configure DLCs using ``GSMIOC_GETCONF_DLCI``/``GSMIOC_SETCONF_DLCI`` ioctl for non-defaults.
#. Obtain base gsmtty number for the used serial port.
Major parts of the initialization program
@ -120,6 +122,8 @@ Config Requester
#. Configure the mux using ``GSMIOC_GETCONF``/``GSMIOC_SETCONF`` ioctl.
#. Configure DLCs using ``GSMIOC_GETCONF_DLCI``/``GSMIOC_SETCONF_DLCI`` ioctl for non-defaults.
#. Obtain base gsmtty number for the used serial port::
#include <stdio.h>

192
drivers/tty/n_gsm.c
View File

@ -128,6 +128,7 @@ struct gsm_msg {
enum gsm_dlci_state {
DLCI_CLOSED,
DLCI_WAITING_CONFIG, /* Waiting for DLCI configuration from user */
DLCI_CONFIGURE, /* Sending PN (for adaption > 1) */
DLCI_OPENING, /* Sending SABM not seen UA */
DLCI_OPEN, /* SABM/UA complete */
@ -330,6 +331,7 @@ struct gsm_mux {
unsigned int t3; /* Power wake-up timer in seconds. */
int n2; /* Retry count */
u8 k; /* Window size */
bool wait_config; /* Wait for configuration by ioctl before DLCI open */
u32 keep_alive; /* Control channel keep-alive in 10ms */
/* Statistics (not currently exposed) */
@ -451,6 +453,7 @@ static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk);
static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len,
u8 ctrl);
static int gsm_send_packet(struct gsm_mux *gsm, struct gsm_msg *msg);
static struct gsm_dlci *gsm_dlci_alloc(struct gsm_mux *gsm, int addr);
static void gsmld_write_trigger(struct gsm_mux *gsm);
static void gsmld_write_task(struct work_struct *work);
@ -2280,6 +2283,7 @@ static void gsm_dlci_begin_open(struct gsm_dlci *dlci)
switch (dlci->state) {
case DLCI_CLOSED:
case DLCI_WAITING_CONFIG:
case DLCI_CLOSING:
dlci->retries = gsm->n2;
if (!need_pn) {
@ -2311,6 +2315,7 @@ static void gsm_dlci_set_opening(struct gsm_dlci *dlci)
{
switch (dlci->state) {
case DLCI_CLOSED:
case DLCI_WAITING_CONFIG:
case DLCI_CLOSING:
dlci->state = DLCI_OPENING;
break;
@ -2319,6 +2324,24 @@ static void gsm_dlci_set_opening(struct gsm_dlci *dlci)
}
}
/**
* gsm_dlci_set_wait_config - wait for channel configuration
* @dlci: DLCI to configure
*
* Wait for a DLCI configuration from the application.
*/
static void gsm_dlci_set_wait_config(struct gsm_dlci *dlci)
{
switch (dlci->state) {
case DLCI_CLOSED:
case DLCI_CLOSING:
dlci->state = DLCI_WAITING_CONFIG;
break;
default:
break;
}
}
/**
* gsm_dlci_begin_close - start channel open procedure
* @dlci: DLCI to open
@ -2453,6 +2476,128 @@ static void gsm_kick_timer(struct timer_list *t)
pr_info("%s TX queue stalled\n", __func__);
}
/**
* gsm_dlci_copy_config_values - copy DLCI configuration
* @dlci: source DLCI
* @dc: configuration structure to fill
*/
static void gsm_dlci_copy_config_values(struct gsm_dlci *dlci, struct gsm_dlci_config *dc)
{
memset(dc, 0, sizeof(*dc));
dc->channel = (u32)dlci->addr;
dc->adaption = (u32)dlci->adaption;
dc->mtu = (u32)dlci->mtu;
dc->priority = (u32)dlci->prio;
if (dlci->ftype == UIH)
dc->i = 1;
else
dc->i = 2;
dc->k = (u32)dlci->k;
}
/**
* gsm_dlci_config - configure DLCI from configuration
* @dlci: DLCI to configure
* @dc: DLCI configuration
* @open: open DLCI after configuration?
*/
static int gsm_dlci_config(struct gsm_dlci *dlci, struct gsm_dlci_config *dc, int open)
{
struct gsm_mux *gsm;
bool need_restart = false;
bool need_open = false;
unsigned int i;
/*
* Check that userspace doesn't put stuff in here to prevent breakages
* in the future.
*/
for (i = 0; i < ARRAY_SIZE(dc->reserved); i++)
if (dc->reserved[i])
return -EINVAL;
if (!dlci)
return -EINVAL;
gsm = dlci->gsm;
/* Stuff we don't support yet - I frame transport */
if (dc->adaption != 1 && dc->adaption != 2)
return -EOPNOTSUPP;
if (dc->mtu > MAX_MTU || dc->mtu < MIN_MTU || dc->mtu > gsm->mru)
return -EINVAL;
if (dc->priority >= 64)
return -EINVAL;
if (dc->i == 0 || dc->i > 2) /* UIH and UI only */
return -EINVAL;
if (dc->k > 7)
return -EINVAL;
/*
* See what is needed for reconfiguration
*/
/* Framing fields */
if (dc->adaption != dlci->adaption)
need_restart = true;
if (dc->mtu != dlci->mtu)
need_restart = true;
if (dc->i != dlci->ftype)
need_restart = true;
/* Requires care */
if (dc->priority != dlci->prio)
need_restart = true;
if ((open && gsm->wait_config) || need_restart)
need_open = true;
if (dlci->state == DLCI_WAITING_CONFIG) {
need_restart = false;
need_open = true;
}
/*
* Close down what is needed, restart and initiate the new
* configuration.
*/
if (need_restart) {
gsm_dlci_begin_close(dlci);
wait_event_interruptible(gsm->event, dlci->state == DLCI_CLOSED);
if (signal_pending(current))
return -EINTR;
}
/*
* Setup the new configuration values
*/
dlci->adaption = (int)dc->adaption;
if (dc->mtu)
dlci->mtu = (unsigned int)dc->mtu;
else
dlci->mtu = gsm->mtu;
if (dc->priority)
dlci->prio = (u8)dc->priority;
else
dlci->prio = roundup(dlci->addr + 1, 8) - 1;
if (dc->i == 1)
dlci->ftype = UIH;
else if (dc->i == 2)
dlci->ftype = UI;
if (dc->k)
dlci->k = (u8)dc->k;
else
dlci->k = gsm->k;
if (need_open) {
if (gsm->initiator)
gsm_dlci_begin_open(dlci);
else
gsm_dlci_set_opening(dlci);
}
return 0;
}
/*
* Allocate/Free DLCI channels
*/
@ -3078,6 +3223,7 @@ static struct gsm_mux *gsm_alloc_mux(void)
gsm->mru = 64; /* Default to encoding 1 so these should be 64 */
gsm->mtu = 64;
gsm->dead = true; /* Avoid early tty opens */
gsm->wait_config = false; /* Disabled */
gsm->keep_alive = 0; /* Disabled */
/* Store the instance to the mux array or abort if no space is
@ -3218,6 +3364,7 @@ static void gsm_copy_config_ext_values(struct gsm_mux *gsm,
struct gsm_config_ext *ce)
{
memset(ce, 0, sizeof(*ce));
ce->wait_config = gsm->wait_config ? 1 : 0;
ce->keep_alive = gsm->keep_alive;
}
@ -3233,7 +3380,12 @@ static int gsm_config_ext(struct gsm_mux *gsm, struct gsm_config_ext *ce)
if (ce->reserved[i])
return -EINVAL;
/*
* Setup the new configuration values
*/
gsm->wait_config = ce->wait_config ? true : false;
gsm->keep_alive = ce->keep_alive;
return 0;
}
@ -3436,6 +3588,14 @@ static int gsmld_open(struct tty_struct *tty)
gsm->encoding = GSM_ADV_OPT;
gsmld_attach_gsm(tty, gsm);
/* The mux will not be activated yet, we wait for correct
* configuration first.
*/
if (gsm->encoding == GSM_BASIC_OPT)
gsm->receive = gsm0_receive;
else
gsm->receive = gsm1_receive;
return 0;
}
@ -4008,7 +4168,6 @@ static int gsmtty_open(struct tty_struct *tty, struct file *filp)
{
struct gsm_dlci *dlci = tty->driver_data;
struct tty_port *port = &dlci->port;
struct gsm_mux *gsm = dlci->gsm;
port->count++;
tty_port_tty_set(port, tty);
@ -4018,10 +4177,15 @@ static int gsmtty_open(struct tty_struct *tty, struct file *filp)
a DM straight back. This is ok as that will have caused a hangup */
tty_port_set_initialized(port, true);
/* Start sending off SABM messages */
if (gsm->initiator)
gsm_dlci_begin_open(dlci);
else
gsm_dlci_set_opening(dlci);
if (!dlci->gsm->wait_config) {
/* Start sending off SABM messages */
if (dlci->gsm->initiator)
gsm_dlci_begin_open(dlci);
else
gsm_dlci_set_opening(dlci);
} else {
gsm_dlci_set_wait_config(dlci);
}
/* And wait for virtual carrier */
return tty_port_block_til_ready(port, tty, filp);
}
@ -4142,6 +4306,7 @@ static int gsmtty_ioctl(struct tty_struct *tty,
{
struct gsm_dlci *dlci = tty->driver_data;
struct gsm_netconfig nc;
struct gsm_dlci_config dc;
int index;
if (dlci->state == DLCI_CLOSED)
@ -4165,6 +4330,23 @@ static int gsmtty_ioctl(struct tty_struct *tty,
gsm_destroy_network(dlci);
mutex_unlock(&dlci->mutex);
return 0;
case GSMIOC_GETCONF_DLCI:
if (copy_from_user(&dc, (void __user *)arg, sizeof(dc)))
return -EFAULT;
if (dc.channel != dlci->addr)
return -EPERM;
gsm_dlci_copy_config_values(dlci, &dc);
if (copy_to_user((void __user *)arg, &dc, sizeof(dc)))
return -EFAULT;
return 0;
case GSMIOC_SETCONF_DLCI:
if (copy_from_user(&dc, (void __user *)arg, sizeof(dc)))
return -EFAULT;
if (dc.channel >= NUM_DLCI)
return -EINVAL;
if (dc.channel != 0 && dc.channel != dlci->addr)
return -EPERM;
return gsm_dlci_config(dlci, &dc, 1);
case TIOCMIWAIT:
return gsm_wait_modem_change(dlci, (u32)arg);
default:

17
include/uapi/linux/gsmmux.h
View File

@ -43,10 +43,25 @@ struct gsm_config_ext {
__u32 keep_alive; /* Control channel keep-alive in 1/100th of a
* second (0 to disable)
*/
__u32 reserved[7]; /* For future use, must be initialized to zero */
__u32 wait_config; /* Wait for DLCI config before opening virtual link? */
__u32 reserved[6]; /* For future use, must be initialized to zero */
};
#define GSMIOC_GETCONF_EXT _IOR('G', 5, struct gsm_config_ext)
#define GSMIOC_SETCONF_EXT _IOW('G', 6, struct gsm_config_ext)
/* Set channel accordingly before calling GSMIOC_GETCONF_DLCI. */
struct gsm_dlci_config {
__u32 channel; /* DLCI (0 for the associated DLCI) */
__u32 adaption; /* Convergence layer type */
__u32 mtu; /* Maximum transfer unit */
__u32 priority; /* Priority (0 for default value) */
__u32 i; /* Frame type (1 = UIH, 2 = UI) */
__u32 k; /* Window size (0 for default value) */
__u32 reserved[8]; /* For future use, must be initialized to zero */
};
#define GSMIOC_GETCONF_DLCI _IOWR('G', 7, struct gsm_dlci_config)
#define GSMIOC_SETCONF_DLCI _IOW('G', 8, struct gsm_dlci_config)
#endif