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alistair23-linux/drivers/parport/daisy.c
Linus Torvalds a3ac7917b7 Revert "parport: daisy: use new parport device model" 
This reverts commit 1aec421120.

Steven Rostedt reports that it causes a hang at bootup and bisected it
to this commit.

The troigger is apparently a module alias for "parport_lowlevel" that
points to "parport_pc", which causes a hang with

    modprobe -q -- parport_lowlevel

blocking forever with a backtrace like this:

    wait_for_completion_killable+0x1c/0x28
    call_usermodehelper_exec+0xa7/0x108
    __request_module+0x351/0x3d8
    get_lowlevel_driver+0x28/0x41 [parport]
    __parport_register_driver+0x39/0x1f4 [parport]
    daisy_drv_init+0x31/0x4f [parport]
    parport_bus_init+0x5d/0x7b [parport]
    parport_default_proc_register+0x26/0x1000 [parport]
    do_one_initcall+0xc2/0x1e0
    do_init_module+0x50/0x1d4
    load_module+0x1c2e/0x21b3
    sys_init_module+0xef/0x117

Supid says:
 "Due to the new device model daisy driver will now try to find the
  parallel ports while trying to register its driver so that it can bind
  with them. Now, since daisy driver is loaded while parport bus is
  initialising the list of parport is still empty and it tries to load
  the lowlevel driver, which has an alias set to parport_pc, now causes
  a deadlock"

But I don't think the daisy driver should be loaded by the parport
initialization in the first place, so let's revert the whole change.

If the daisy driver can just initialize separately on its own (like a
driver should), instead of hooking into the parport init sequence
directly, this issue probably would go away.

Reported-and-bisected-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reported-by: Michal Kubecek <mkubecek@suse.cz>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-25 14:49:00 -07:00

483 lines
12 KiB
C
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/*
* IEEE 1284.3 Parallel port daisy chain and multiplexor code
*
* Copyright (C) 1999, 2000 Tim Waugh <tim@cyberelk.demon.co.uk>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* ??-12-1998: Initial implementation.
* 31-01-1999: Make port-cloning transparent.
* 13-02-1999: Move DeviceID technique from parport_probe.
* 13-03-1999: Get DeviceID from non-IEEE 1284.3 devices too.
* 22-02-2000: Count devices that are actually detected.
*
* Any part of this program may be used in documents licensed under
* the GNU Free Documentation License, Version 1.1 or any later version
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/parport.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/sched/signal.h>
#include <asm/current.h>
#include <linux/uaccess.h>
#undef DEBUG
#ifdef DEBUG
#define DPRINTK(stuff...) printk(stuff)
#else
#define DPRINTK(stuff...)
#endif
static struct daisydev {
struct daisydev *next;
struct parport *port;
int daisy;
int devnum;
} *topology = NULL;
static DEFINE_SPINLOCK(topology_lock);
static int numdevs;
/* Forward-declaration of lower-level functions. */
static int mux_present(struct parport *port);
static int num_mux_ports(struct parport *port);
static int select_port(struct parport *port);
static int assign_addrs(struct parport *port);
/* Add a device to the discovered topology. */
static void add_dev(int devnum, struct parport *port, int daisy)
{
struct daisydev *newdev, **p;
newdev = kmalloc(sizeof(struct daisydev), GFP_KERNEL);
if (newdev) {
newdev->port = port;
newdev->daisy = daisy;
newdev->devnum = devnum;
spin_lock(&topology_lock);
for (p = &topology; *p && (*p)->devnum<devnum; p = &(*p)->next)
;
newdev->next = *p;
*p = newdev;
spin_unlock(&topology_lock);
}
}
/* Clone a parport (actually, make an alias). */
static struct parport *clone_parport(struct parport *real, int muxport)
{
struct parport *extra = parport_register_port(real->base,
real->irq,
real->dma,
real->ops);
if (extra) {
extra->portnum = real->portnum;
extra->physport = real;
extra->muxport = muxport;
real->slaves[muxport-1] = extra;
}
return extra;
}
/* Discover the IEEE1284.3 topology on a port -- muxes and daisy chains.
* Return value is number of devices actually detected. */
int parport_daisy_init(struct parport *port)
{
int detected = 0;
char *deviceid;
static const char *th[] = { /*0*/"th", "st", "nd", "rd", "th" };
int num_ports;
int i;
int last_try = 0;
again:
/* Because this is called before any other devices exist,
* we don't have to claim exclusive access. */
/* If mux present on normal port, need to create new
* parports for each extra port. */
if (port->muxport < 0 && mux_present(port) &&
/* don't be fooled: a mux must have 2 or 4 ports. */
((num_ports = num_mux_ports(port)) == 2 || num_ports == 4)) {
/* Leave original as port zero. */
port->muxport = 0;
printk(KERN_INFO
"%s: 1st (default) port of %d-way multiplexor\n",
port->name, num_ports);
for (i = 1; i < num_ports; i++) {
/* Clone the port. */
struct parport *extra = clone_parport(port, i);
if (!extra) {
if (signal_pending(current))
break;
schedule();
continue;
}
printk(KERN_INFO
"%s: %d%s port of %d-way multiplexor on %s\n",
extra->name, i + 1, th[i + 1], num_ports,
port->name);
/* Analyse that port too. We won't recurse
forever because of the 'port->muxport < 0'
test above. */
parport_daisy_init(extra);
}
}
if (port->muxport >= 0)
select_port(port);
parport_daisy_deselect_all(port);
detected += assign_addrs(port);
/* Count the potential legacy device at the end. */
add_dev(numdevs++, port, -1);
/* Find out the legacy device's IEEE 1284 device ID. */
deviceid = kmalloc(1024, GFP_KERNEL);
if (deviceid) {
if (parport_device_id(numdevs - 1, deviceid, 1024) > 2)
detected++;
kfree(deviceid);
}
if (!detected && !last_try) {
/* No devices were detected. Perhaps they are in some
funny state; let's try to reset them and see if
they wake up. */
parport_daisy_fini(port);
parport_write_control(port, PARPORT_CONTROL_SELECT);
udelay(50);
parport_write_control(port,
PARPORT_CONTROL_SELECT |
PARPORT_CONTROL_INIT);
udelay(50);
last_try = 1;
goto again;
}
return detected;
}
/* Forget about devices on a physical port. */
void parport_daisy_fini(struct parport *port)
{
struct daisydev **p;
spin_lock(&topology_lock);
p = &topology;
while (*p) {
struct daisydev *dev = *p;
if (dev->port != port) {
p = &dev->next;
continue;
}
*p = dev->next;
kfree(dev);
}
/* Gaps in the numbering could be handled better. How should
someone enumerate through all IEEE1284.3 devices in the
topology?. */
if (!topology) numdevs = 0;
spin_unlock(&topology_lock);
return;
}
/**
* parport_open - find a device by canonical device number
* @devnum: canonical device number
* @name: name to associate with the device
*
* This function is similar to parport_register_device(), except
* that it locates a device by its number rather than by the port
* it is attached to.
*
* All parameters except for @devnum are the same as for
* parport_register_device(). The return value is the same as
* for parport_register_device().
**/
struct pardevice *parport_open(int devnum, const char *name)
{
struct daisydev *p = topology;
struct parport *port;
struct pardevice *dev;
int daisy;
spin_lock(&topology_lock);
while (p && p->devnum != devnum)
p = p->next;
if (!p) {
spin_unlock(&topology_lock);
return NULL;
}
daisy = p->daisy;
port = parport_get_port(p->port);
spin_unlock(&topology_lock);
dev = parport_register_device(port, name, NULL, NULL, NULL, 0, NULL);
parport_put_port(port);
if (!dev)
return NULL;
dev->daisy = daisy;
/* Check that there really is a device to select. */
if (daisy >= 0) {
int selected;
parport_claim_or_block(dev);
selected = port->daisy;
parport_release(dev);
if (selected != daisy) {
/* No corresponding device. */
parport_unregister_device(dev);
return NULL;
}
}
return dev;
}
/**
* parport_close - close a device opened with parport_open()
* @dev: device to close
*
* This is to parport_open() as parport_unregister_device() is to
* parport_register_device().
**/
void parport_close(struct pardevice *dev)
{
parport_unregister_device(dev);
}
/* Send a daisy-chain-style CPP command packet. */
static int cpp_daisy(struct parport *port, int cmd)
{
unsigned char s;
parport_data_forward(port);
parport_write_data(port, 0xaa); udelay(2);
parport_write_data(port, 0x55); udelay(2);
parport_write_data(port, 0x00); udelay(2);
parport_write_data(port, 0xff); udelay(2);
s = parport_read_status(port) & (PARPORT_STATUS_BUSY
| PARPORT_STATUS_PAPEROUT
| PARPORT_STATUS_SELECT
| PARPORT_STATUS_ERROR);
if (s != (PARPORT_STATUS_BUSY
| PARPORT_STATUS_PAPEROUT
| PARPORT_STATUS_SELECT
| PARPORT_STATUS_ERROR)) {
DPRINTK(KERN_DEBUG "%s: cpp_daisy: aa5500ff(%02x)\n",
port->name, s);
return -ENXIO;
}
parport_write_data(port, 0x87); udelay(2);
s = parport_read_status(port) & (PARPORT_STATUS_BUSY
| PARPORT_STATUS_PAPEROUT
| PARPORT_STATUS_SELECT
| PARPORT_STATUS_ERROR);
if (s != (PARPORT_STATUS_SELECT | PARPORT_STATUS_ERROR)) {
DPRINTK(KERN_DEBUG "%s: cpp_daisy: aa5500ff87(%02x)\n",
port->name, s);
return -ENXIO;
}
parport_write_data(port, 0x78); udelay(2);
parport_write_data(port, cmd); udelay(2);
parport_frob_control(port,
PARPORT_CONTROL_STROBE,
PARPORT_CONTROL_STROBE);
udelay(1);
s = parport_read_status(port);
parport_frob_control(port, PARPORT_CONTROL_STROBE, 0);
udelay(1);
parport_write_data(port, 0xff); udelay(2);
return s;
}
/* Send a mux-style CPP command packet. */
static int cpp_mux(struct parport *port, int cmd)
{
unsigned char s;
int rc;
parport_data_forward(port);
parport_write_data(port, 0xaa); udelay(2);
parport_write_data(port, 0x55); udelay(2);
parport_write_data(port, 0xf0); udelay(2);
parport_write_data(port, 0x0f); udelay(2);
parport_write_data(port, 0x52); udelay(2);
parport_write_data(port, 0xad); udelay(2);
parport_write_data(port, cmd); udelay(2);
s = parport_read_status(port);
if (!(s & PARPORT_STATUS_ACK)) {
DPRINTK(KERN_DEBUG "%s: cpp_mux: aa55f00f52ad%02x(%02x)\n",
port->name, cmd, s);
return -EIO;
}
rc = (((s & PARPORT_STATUS_SELECT ? 1 : 0) << 0) |
((s & PARPORT_STATUS_PAPEROUT ? 1 : 0) << 1) |
((s & PARPORT_STATUS_BUSY ? 0 : 1) << 2) |
((s & PARPORT_STATUS_ERROR ? 0 : 1) << 3));
return rc;
}
void parport_daisy_deselect_all(struct parport *port)
{
cpp_daisy(port, 0x30);
}
int parport_daisy_select(struct parport *port, int daisy, int mode)
{
switch (mode)
{
// For these modes we should switch to EPP mode:
case IEEE1284_MODE_EPP:
case IEEE1284_MODE_EPPSL:
case IEEE1284_MODE_EPPSWE:
return !(cpp_daisy(port, 0x20 + daisy) &
PARPORT_STATUS_ERROR);
// For these modes we should switch to ECP mode:
case IEEE1284_MODE_ECP:
case IEEE1284_MODE_ECPRLE:
case IEEE1284_MODE_ECPSWE:
return !(cpp_daisy(port, 0xd0 + daisy) &
PARPORT_STATUS_ERROR);
// Nothing was told for BECP in Daisy chain specification.
// May be it's wise to use ECP?
case IEEE1284_MODE_BECP:
// Others use compat mode
case IEEE1284_MODE_NIBBLE:
case IEEE1284_MODE_BYTE:
case IEEE1284_MODE_COMPAT:
default:
return !(cpp_daisy(port, 0xe0 + daisy) &
PARPORT_STATUS_ERROR);
}
}
static int mux_present(struct parport *port)
{
return cpp_mux(port, 0x51) == 3;
}
static int num_mux_ports(struct parport *port)
{
return cpp_mux(port, 0x58);
}
static int select_port(struct parport *port)
{
int muxport = port->muxport;
return cpp_mux(port, 0x60 + muxport) == muxport;
}
static int assign_addrs(struct parport *port)
{
unsigned char s;
unsigned char daisy;
int thisdev = numdevs;
int detected;
char *deviceid;
parport_data_forward(port);
parport_write_data(port, 0xaa); udelay(2);
parport_write_data(port, 0x55); udelay(2);
parport_write_data(port, 0x00); udelay(2);
parport_write_data(port, 0xff); udelay(2);
s = parport_read_status(port) & (PARPORT_STATUS_BUSY
| PARPORT_STATUS_PAPEROUT
| PARPORT_STATUS_SELECT
| PARPORT_STATUS_ERROR);
if (s != (PARPORT_STATUS_BUSY
| PARPORT_STATUS_PAPEROUT
| PARPORT_STATUS_SELECT
| PARPORT_STATUS_ERROR)) {
DPRINTK(KERN_DEBUG "%s: assign_addrs: aa5500ff(%02x)\n",
port->name, s);
return 0;
}
parport_write_data(port, 0x87); udelay(2);
s = parport_read_status(port) & (PARPORT_STATUS_BUSY
| PARPORT_STATUS_PAPEROUT
| PARPORT_STATUS_SELECT
| PARPORT_STATUS_ERROR);
if (s != (PARPORT_STATUS_SELECT | PARPORT_STATUS_ERROR)) {
DPRINTK(KERN_DEBUG "%s: assign_addrs: aa5500ff87(%02x)\n",
port->name, s);
return 0;
}
parport_write_data(port, 0x78); udelay(2);
s = parport_read_status(port);
for (daisy = 0;
(s & (PARPORT_STATUS_PAPEROUT|PARPORT_STATUS_SELECT))
== (PARPORT_STATUS_PAPEROUT|PARPORT_STATUS_SELECT)
&& daisy < 4;
++daisy) {
parport_write_data(port, daisy);
udelay(2);
parport_frob_control(port,
PARPORT_CONTROL_STROBE,
PARPORT_CONTROL_STROBE);
udelay(1);
parport_frob_control(port, PARPORT_CONTROL_STROBE, 0);
udelay(1);
add_dev(numdevs++, port, daisy);
/* See if this device thought it was the last in the
* chain. */
if (!(s & PARPORT_STATUS_BUSY))
break;
/* We are seeing pass through status now. We see
last_dev from next device or if last_dev does not
work status lines from some non-daisy chain
device. */
s = parport_read_status(port);
}
parport_write_data(port, 0xff); udelay(2);
detected = numdevs - thisdev;
DPRINTK(KERN_DEBUG "%s: Found %d daisy-chained devices\n", port->name,
detected);
/* Ask the new devices to introduce themselves. */
deviceid = kmalloc(1024, GFP_KERNEL);
if (!deviceid) return 0;
for (daisy = 0; thisdev < numdevs; thisdev++, daisy++)
parport_device_id(thisdev, deviceid, 1024);
kfree(deviceid);
return detected;
}
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