blob: f8c08fb9891d7495fbfcf9705413727d554c3733 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2015-2017 Pengutronix, Uwe Kleine-K├Ânig <kernel@pengutronix.de>
*/
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include "siox.h"
/*
* The lowest bit in the SIOX status word signals if the in-device watchdog is
* ok. If the bit is set, the device is functional.
*
* On writing the watchdog timer is reset when this bit toggles.
*/
#define SIOX_STATUS_WDG 0x01
/*
* Bits 1 to 3 of the status word read as the bitwise negation of what was
* clocked in before. The value clocked in is changed in each cycle and so
* allows to detect transmit/receive problems.
*/
#define SIOX_STATUS_COUNTER 0x0e
/*
* Each Siox-Device has a 4 bit type number that is neither 0 nor 15. This is
* available in the upper nibble of the read status.
*
* On write these bits are DC.
*/
#define SIOX_STATUS_TYPE 0xf0
#define CREATE_TRACE_POINTS
#include <trace/events/siox.h>
static bool siox_is_registered;
static void siox_master_lock(struct siox_master *smaster)
{
mutex_lock(&smaster->lock);
}
static void siox_master_unlock(struct siox_master *smaster)
{
mutex_unlock(&smaster->lock);
}
static inline u8 siox_status_clean(u8 status_read, u8 status_written)
{
/*
* bits 3:1 of status sample the respective bit in the status
* byte written in the previous cycle but inverted. So if you wrote the
* status word as 0xa before (counter = 0b101), it is expected to get
* back the counter bits as 0b010.
*
* So given the last status written this function toggles the there
* unset counter bits in the read value such that the counter bits in
* the return value are all zero iff the bits were read as expected to
* simplify error detection.
*/
return status_read ^ (~status_written & 0xe);
}
static bool siox_device_counter_error(struct siox_device *sdevice,
u8 status_clean)
{
return (status_clean & SIOX_STATUS_COUNTER) != 0;
}
static bool siox_device_type_error(struct siox_device *sdevice, u8 status_clean)
{
u8 statustype = (status_clean & SIOX_STATUS_TYPE) >> 4;
/*
* If the device knows which value the type bits should have, check
* against this value otherwise just rule out the invalid values 0b0000
* and 0b1111.
*/
if (sdevice->statustype) {
if (statustype != sdevice->statustype)
return true;
} else {
switch (statustype) {
case 0:
case 0xf:
return true;
}
}
return false;
}
static bool siox_device_wdg_error(struct siox_device *sdevice, u8 status_clean)
{
return (status_clean & SIOX_STATUS_WDG) == 0;
}
/*
* If there is a type or counter error the device is called "unsynced".
*/
bool siox_device_synced(struct siox_device *sdevice)
{
if (siox_device_type_error(sdevice, sdevice->status_read_clean))
return false;
return !siox_device_counter_error(sdevice, sdevice->status_read_clean);
}
EXPORT_SYMBOL_GPL(siox_device_synced);
/*
* A device is called "connected" if it is synced and the watchdog is not
* asserted.
*/
bool siox_device_connected(struct siox_device *sdevice)
{
if (!siox_device_synced(sdevice))
return false;
return !siox_device_wdg_error(sdevice, sdevice->status_read_clean);
}
EXPORT_SYMBOL_GPL(siox_device_connected);
static void siox_poll(struct siox_master *smaster)
{
struct siox_device *sdevice;
size_t i = smaster->setbuf_len;
unsigned int devno = 0;
int unsync_error = 0;
smaster->last_poll = jiffies;
/*
* The counter bits change in each second cycle, the watchdog bit
* toggles each time.
* The counter bits hold values from [0, 6]. 7 would be possible
* theoretically but the protocol designer considered that a bad idea
* for reasons unknown today. (Maybe that's because then the status read
* back has only zeros in the counter bits then which might be confused
* with a stuck-at-0 error. But for the same reason (with s/0/1/) 0
* could be skipped.)
*/
if (++smaster->status > 0x0d)
smaster->status = 0;
memset(smaster->buf, 0, smaster->setbuf_len);
/* prepare data pushed out to devices in buf[0..setbuf_len) */
list_for_each_entry(sdevice, &smaster->devices, node) {
struct siox_driver *sdriver =
to_siox_driver(sdevice->dev.driver);
sdevice->status_written = smaster->status;
i -= sdevice->inbytes;
/*
* If the device or a previous one is unsynced, don't pet the
* watchdog. This is done to ensure that the device is kept in
* reset when something is wrong.
*/
if (!siox_device_synced(sdevice))
unsync_error = 1;
if (sdriver && !unsync_error)
sdriver->set_data(sdevice, sdevice->status_written,
&smaster->buf[i + 1]);
else
/*
* Don't trigger watchdog if there is no driver or a
* sync problem
*/
sdevice->status_written &= ~SIOX_STATUS_WDG;
smaster->buf[i] = sdevice->status_written;
trace_siox_set_data(smaster, sdevice, devno, i);
devno++;
}
smaster->pushpull(smaster, smaster->setbuf_len, smaster->buf,
smaster->getbuf_len,
smaster->buf + smaster->setbuf_len);
unsync_error = 0;
/* interpret data pulled in from devices in buf[setbuf_len..] */
devno = 0;
i = smaster->setbuf_len;
list_for_each_entry(sdevice, &smaster->devices, node) {
struct siox_driver *sdriver =
to_siox_driver(sdevice->dev.driver);
u8 status = smaster->buf[i + sdevice->outbytes - 1];
u8 status_clean;
u8 prev_status_clean = sdevice->status_read_clean;
bool synced = true;
bool connected = true;
if (!siox_device_synced(sdevice))
unsync_error = 1;
/*
* If the watchdog bit wasn't toggled in this cycle, report the
* watchdog as active to give a consistent view for drivers and
* sysfs consumers.
*/
if (!sdriver || unsync_error)
status &= ~SIOX_STATUS_WDG;
status_clean =
siox_status_clean(status,
sdevice->status_written_lastcycle);
/* Check counter and type bits */
if (siox_device_counter_error(sdevice, status_clean) ||
siox_device_type_error(sdevice, status_clean)) {
bool prev_error;
synced = false;
/* only report a new error if the last cycle was ok */
prev_error =
siox_device_counter_error(sdevice,
prev_status_clean) ||
siox_device_type_error(sdevice,
prev_status_clean);
if (!prev_error) {
sdevice->status_errors++;
sysfs_notify_dirent(sdevice->status_errors_kn);
}
}
/* If the device is unsynced report the watchdog as active */
if (!synced) {
status &= ~SIOX_STATUS_WDG;
status_clean &= ~SIOX_STATUS_WDG;
}
if (siox_device_wdg_error(sdevice, status_clean))
connected = false;
/* The watchdog state changed just now */
if ((status_clean ^ prev_status_clean) & SIOX_STATUS_WDG) {
sysfs_notify_dirent(sdevice->watchdog_kn);
if (siox_device_wdg_error(sdevice, status_clean)) {
struct kernfs_node *wd_errs =
sdevice->watchdog_errors_kn;
sdevice->watchdog_errors++;
sysfs_notify_dirent(wd_errs);
}
}
if (connected != sdevice->connected)
sysfs_notify_dirent(sdevice->connected_kn);
sdevice->status_read_clean = status_clean;
sdevice->status_written_lastcycle = sdevice->status_written;
sdevice->connected = connected;
trace_siox_get_data(smaster, sdevice, devno, status_clean, i);
/* only give data read to driver if the device is connected */
if (sdriver && connected)
sdriver->get_data(sdevice, &smaster->buf[i]);
devno++;
i += sdevice->outbytes;
}
}
static int siox_poll_thread(void *data)
{
struct siox_master *smaster = data;
signed long timeout = 0;
get_device(&smaster->dev);
for (;;) {
if (kthread_should_stop()) {
put_device(&smaster->dev);
return 0;
}
siox_master_lock(smaster);
if (smaster->active) {
unsigned long next_poll =
smaster->last_poll + smaster->poll_interval;
if (time_is_before_eq_jiffies(next_poll))
siox_poll(smaster);
timeout = smaster->poll_interval -
(jiffies - smaster->last_poll);
} else {
timeout = MAX_SCHEDULE_TIMEOUT;
}
/*
* Set the task to idle while holding the lock. This makes sure
* that we don't sleep too long when the bus is reenabled before
* schedule_timeout is reached.
*/
if (timeout > 0)
set_current_state(TASK_IDLE);
siox_master_unlock(smaster);
if (timeout > 0)
schedule_timeout(timeout);
/*
* I'm not clear if/why it is important to set the state to
* RUNNING again, but it fixes a "do not call blocking ops when
* !TASK_RUNNING;"-warning.
*/
set_current_state(TASK_RUNNING);
}
}
static int __siox_start(struct siox_master *smaster)
{
if (!(smaster->setbuf_len + smaster->getbuf_len))
return -ENODEV;
if (!smaster->buf)
return -ENOMEM;
if (smaster->active)
return 0;
smaster->active = 1;
wake_up_process(smaster->poll_thread);
return 1;
}
static int siox_start(struct siox_master *smaster)
{
int ret;
siox_master_lock(smaster);
ret = __siox_start(smaster);
siox_master_unlock(smaster);
return ret;
}
static int __siox_stop(struct siox_master *smaster)
{
if (smaster->active) {
struct siox_device *sdevice;
smaster->active = 0;
list_for_each_entry(sdevice, &smaster->devices, node) {
if (sdevice->connected)
sysfs_notify_dirent(sdevice->connected_kn);
sdevice->connected = false;
}
return 1;
}
return 0;
}
static int siox_stop(struct siox_master *smaster)
{
int ret;
siox_master_lock(smaster);
ret = __siox_stop(smaster);
siox_master_unlock(smaster);
return ret;
}
static ssize_t type_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct siox_device *sdev = to_siox_device(dev);
return sprintf(buf, "%s\n", sdev->type);
}
static DEVICE_ATTR_RO(type);
static ssize_t inbytes_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct siox_device *sdev = to_siox_device(dev);
return sprintf(buf, "%zu\n", sdev->inbytes);
}
static DEVICE_ATTR_RO(inbytes);
static ssize_t outbytes_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct siox_device *sdev = to_siox_device(dev);
return sprintf(buf, "%zu\n", sdev->outbytes);
}
static DEVICE_ATTR_RO(outbytes);
static ssize_t status_errors_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct siox_device *sdev = to_siox_device(dev);
unsigned int status_errors;
siox_master_lock(sdev->smaster);
status_errors = sdev->status_errors;
siox_master_unlock(sdev->smaster);
return sprintf(buf, "%u\n", status_errors);
}
static DEVICE_ATTR_RO(status_errors);
static ssize_t connected_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct siox_device *sdev = to_siox_device(dev);
bool connected;
siox_master_lock(sdev->smaster);
connected = sdev->connected;
siox_master_unlock(sdev->smaster);
return sprintf(buf, "%u\n", connected);
}
static DEVICE_ATTR_RO(connected);
static ssize_t watchdog_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct siox_device *sdev = to_siox_device(dev);
u8 status;
siox_master_lock(sdev->smaster);
status = sdev->status_read_clean;
siox_master_unlock(sdev->smaster);
return sprintf(buf, "%d\n", status & SIOX_STATUS_WDG);
}
static DEVICE_ATTR_RO(watchdog);
static ssize_t watchdog_errors_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct siox_device *sdev = to_siox_device(dev);
unsigned int watchdog_errors;
siox_master_lock(sdev->smaster);
watchdog_errors = sdev->watchdog_errors;
siox_master_unlock(sdev->smaster);
return sprintf(buf, "%u\n", watchdog_errors);
}
static DEVICE_ATTR_RO(watchdog_errors);
static struct attribute *siox_device_attrs[] = {
&dev_attr_type.attr,
&dev_attr_inbytes.attr,
&dev_attr_outbytes.attr,
&dev_attr_status_errors.attr,
&dev_attr_connected.attr,
&dev_attr_watchdog.attr,
&dev_attr_watchdog_errors.attr,
NULL
};
ATTRIBUTE_GROUPS(siox_device);
static void siox_device_release(struct device *dev)
{
struct siox_device *sdevice = to_siox_device(dev);
kfree(sdevice);
}
static struct device_type siox_device_type = {
.groups = siox_device_groups,
.release = siox_device_release,
};
static int siox_match(struct device *dev, struct device_driver *drv)
{
if (dev->type != &siox_device_type)
return 0;
/* up to now there is only a single driver so keeping this simple */
return 1;
}
static struct bus_type siox_bus_type = {
.name = "siox",
.match = siox_match,
};
static int siox_driver_probe(struct device *dev)
{
struct siox_driver *sdriver = to_siox_driver(dev->driver);
struct siox_device *sdevice = to_siox_device(dev);
int ret;
ret = sdriver->probe(sdevice);
return ret;
}
static int siox_driver_remove(struct device *dev)
{
struct siox_driver *sdriver =
container_of(dev->driver, struct siox_driver, driver);
struct siox_device *sdevice = to_siox_device(dev);
int ret;
ret = sdriver->remove(sdevice);
return ret;
}
static void siox_driver_shutdown(struct device *dev)
{
struct siox_driver *sdriver =
container_of(dev->driver, struct siox_driver, driver);
struct siox_device *sdevice = to_siox_device(dev);
sdriver->shutdown(sdevice);
}
static ssize_t active_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct siox_master *smaster = to_siox_master(dev);
return sprintf(buf, "%d\n", smaster->active);
}
static ssize_t active_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct siox_master *smaster = to_siox_master(dev);
int ret;
int active;
ret = kstrtoint(buf, 0, &active);
if (ret < 0)
return ret;
if (active)
ret = siox_start(smaster);
else
ret = siox_stop(smaster);
if (ret < 0)
return ret;
return count;
}
static DEVICE_ATTR_RW(active);
static struct siox_device *siox_device_add(struct siox_master *smaster,
const char *type, size_t inbytes,
size_t outbytes, u8 statustype);
static ssize_t device_add_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct siox_master *smaster = to_siox_master(dev);
int ret;
char type[20] = "";
size_t inbytes = 0, outbytes = 0;
u8 statustype = 0;
ret = sscanf(buf, "%19s %zu %zu %hhu", type, &inbytes,
&outbytes, &statustype);
if (ret != 3 && ret != 4)
return -EINVAL;
if (strcmp(type, "siox-12x8") || inbytes != 2 || outbytes != 4)
return -EINVAL;
siox_device_add(smaster, "siox-12x8", inbytes, outbytes, statustype);
return count;
}
static DEVICE_ATTR_WO(device_add);
static void siox_device_remove(struct siox_master *smaster);
static ssize_t device_remove_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct siox_master *smaster = to_siox_master(dev);
/* XXX? require to write <type> <inbytes> <outbytes> */
siox_device_remove(smaster);
return count;
}
static DEVICE_ATTR_WO(device_remove);
static ssize_t poll_interval_ns_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct siox_master *smaster = to_siox_master(dev);
return sprintf(buf, "%lld\n", jiffies_to_nsecs(smaster->poll_interval));
}
static ssize_t poll_interval_ns_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct siox_master *smaster = to_siox_master(dev);
int ret;
u64 val;
ret = kstrtou64(buf, 0, &val);
if (ret < 0)
return ret;
siox_master_lock(smaster);
smaster->poll_interval = nsecs_to_jiffies(val);
siox_master_unlock(smaster);
return count;
}
static DEVICE_ATTR_RW(poll_interval_ns);
static struct attribute *siox_master_attrs[] = {
&dev_attr_active.attr,
&dev_attr_device_add.attr,
&dev_attr_device_remove.attr,
&dev_attr_poll_interval_ns.attr,
NULL
};
ATTRIBUTE_GROUPS(siox_master);
static void siox_master_release(struct device *dev)
{
struct siox_master *smaster = to_siox_master(dev);
kfree(smaster);
}
static struct device_type siox_master_type = {
.groups = siox_master_groups,
.release = siox_master_release,
};
struct siox_master *siox_master_alloc(struct device *dev,
size_t size)
{
struct siox_master *smaster;
if (!dev)
return NULL;
smaster = kzalloc(sizeof(*smaster) + size, GFP_KERNEL);
if (!smaster)
return NULL;
device_initialize(&smaster->dev);
smaster->busno = -1;
smaster->dev.bus = &siox_bus_type;
smaster->dev.type = &siox_master_type;
smaster->dev.parent = dev;
smaster->poll_interval = DIV_ROUND_UP(HZ, 40);
dev_set_drvdata(&smaster->dev, &smaster[1]);
return smaster;
}
EXPORT_SYMBOL_GPL(siox_master_alloc);
int siox_master_register(struct siox_master *smaster)
{
int ret;
if (!siox_is_registered)
return -EPROBE_DEFER;
if (!smaster->pushpull)
return -EINVAL;
dev_set_name(&smaster->dev, "siox-%d", smaster->busno);
mutex_init(&smaster->lock);
INIT_LIST_HEAD(&smaster->devices);
smaster->last_poll = jiffies;
smaster->poll_thread = kthread_run(siox_poll_thread, smaster,
"siox-%d", smaster->busno);
if (IS_ERR(smaster->poll_thread)) {
smaster->active = 0;
return PTR_ERR(smaster->poll_thread);
}
ret = device_add(&smaster->dev);
if (ret)
kthread_stop(smaster->poll_thread);
return ret;
}
EXPORT_SYMBOL_GPL(siox_master_register);
void siox_master_unregister(struct siox_master *smaster)
{
/* remove device */
device_del(&smaster->dev);
siox_master_lock(smaster);
__siox_stop(smaster);
while (smaster->num_devices) {
struct siox_device *sdevice;
sdevice = container_of(smaster->devices.prev,
struct siox_device, node);
list_del(&sdevice->node);
smaster->num_devices--;
siox_master_unlock(smaster);
device_unregister(&sdevice->dev);
siox_master_lock(smaster);
}
siox_master_unlock(smaster);
put_device(&smaster->dev);
}
EXPORT_SYMBOL_GPL(siox_master_unregister);
static struct siox_device *siox_device_add(struct siox_master *smaster,
const char *type, size_t inbytes,
size_t outbytes, u8 statustype)
{
struct siox_device *sdevice;
int ret;
size_t buf_len;
sdevice = kzalloc(sizeof(*sdevice), GFP_KERNEL);
if (!sdevice)
return ERR_PTR(-ENOMEM);
sdevice->type = type;
sdevice->inbytes = inbytes;
sdevice->outbytes = outbytes;
sdevice->statustype = statustype;
sdevice->smaster = smaster;
sdevice->dev.parent = &smaster->dev;
sdevice->dev.bus = &siox_bus_type;
sdevice->dev.type = &siox_device_type;
siox_master_lock(smaster);
dev_set_name(&sdevice->dev, "siox-%d-%d",
smaster->busno, smaster->num_devices);
buf_len = smaster->setbuf_len + inbytes +
smaster->getbuf_len + outbytes;
if (smaster->buf_len < buf_len) {
u8 *buf = krealloc(smaster->buf, buf_len, GFP_KERNEL);
if (!buf) {
dev_err(&smaster->dev,
"failed to realloc buffer to %zu\n", buf_len);
ret = -ENOMEM;
goto err_buf_alloc;
}
smaster->buf_len = buf_len;
smaster->buf = buf;
}
ret = device_register(&sdevice->dev);
if (ret) {
dev_err(&smaster->dev, "failed to register device: %d\n", ret);
goto err_device_register;
}
smaster->num_devices++;
list_add_tail(&sdevice->node, &smaster->devices);
smaster->setbuf_len += sdevice->inbytes;
smaster->getbuf_len += sdevice->outbytes;
sdevice->status_errors_kn = sysfs_get_dirent(sdevice->dev.kobj.sd,
"status_errors");
sdevice->watchdog_kn = sysfs_get_dirent(sdevice->dev.kobj.sd,
"watchdog");
sdevice->watchdog_errors_kn = sysfs_get_dirent(sdevice->dev.kobj.sd,
"watchdog_errors");
sdevice->connected_kn = sysfs_get_dirent(sdevice->dev.kobj.sd,
"connected");
siox_master_unlock(smaster);
return sdevice;
err_device_register:
/* don't care to make the buffer smaller again */
err_buf_alloc:
siox_master_unlock(smaster);
kfree(sdevice);
return ERR_PTR(ret);
}
static void siox_device_remove(struct siox_master *smaster)
{
struct siox_device *sdevice;
siox_master_lock(smaster);
if (!smaster->num_devices) {
siox_master_unlock(smaster);
return;
}
sdevice = container_of(smaster->devices.prev, struct siox_device, node);
list_del(&sdevice->node);
smaster->num_devices--;
smaster->setbuf_len -= sdevice->inbytes;
smaster->getbuf_len -= sdevice->outbytes;
if (!smaster->num_devices)
__siox_stop(smaster);
siox_master_unlock(smaster);
/*
* This must be done without holding the master lock because we're
* called from device_remove_store which also holds a sysfs mutex.
* device_unregister tries to aquire the same lock.
*/
device_unregister(&sdevice->dev);
}
int __siox_driver_register(struct siox_driver *sdriver, struct module *owner)
{
int ret;
if (unlikely(!siox_is_registered))
return -EPROBE_DEFER;
if (!sdriver->set_data && !sdriver->get_data) {
pr_err("Driver %s doesn't provide needed callbacks\n",
sdriver->driver.name);
return -EINVAL;
}
sdriver->driver.owner = owner;
sdriver->driver.bus = &siox_bus_type;
if (sdriver->probe)
sdriver->driver.probe = siox_driver_probe;
if (sdriver->remove)
sdriver->driver.remove = siox_driver_remove;
if (sdriver->shutdown)
sdriver->driver.shutdown = siox_driver_shutdown;
ret = driver_register(&sdriver->driver);
if (ret)
pr_err("Failed to register siox driver %s (%d)\n",
sdriver->driver.name, ret);
return ret;
}
EXPORT_SYMBOL_GPL(__siox_driver_register);
static int __init siox_init(void)
{
int ret;
ret = bus_register(&siox_bus_type);
if (ret) {
pr_err("Registration of SIOX bus type failed: %d\n", ret);
return ret;
}
siox_is_registered = true;
return 0;
}
subsys_initcall(siox_init);
static void __exit siox_exit(void)
{
bus_unregister(&siox_bus_type);
}
module_exit(siox_exit);
MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>");
MODULE_DESCRIPTION("Eckelmann SIOX driver core");
MODULE_LICENSE("GPL v2");