diff options
Diffstat (limited to 'drivers/siox/siox-core.c')
| -rw-r--r-- | drivers/siox/siox-core.c | 936 |
1 files changed, 936 insertions, 0 deletions
diff --git a/drivers/siox/siox-core.c b/drivers/siox/siox-core.c new file mode 100644 index 000000000..e0ffef6e9 --- /dev/null +++ b/drivers/siox/siox-core.c @@ -0,0 +1,936 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2015-2017 Pengutronix, Uwe Kleine-König <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 */ + put_device(&sdevice->dev); + sdevice = NULL; + +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"); |