| /* The industrial I/O simple minimally locked ring buffer. |
| * |
| * Copyright (c) 2008 Jonathan Cameron |
| * |
| * This program is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 as published by |
| * the Free Software Foundation. |
| */ |
| |
| #include <linux/slab.h> |
| #include <linux/kernel.h> |
| #include <linux/module.h> |
| #include <linux/device.h> |
| #include <linux/workqueue.h> |
| #include "ring_sw.h" |
| #include "trigger.h" |
| |
| static inline int __iio_allocate_sw_ring_buffer(struct iio_sw_ring_buffer *ring, |
| int bytes_per_datum, int length) |
| { |
| if ((length == 0) || (bytes_per_datum == 0)) |
| return -EINVAL; |
| __iio_update_ring_buffer(&ring->buf, bytes_per_datum, length); |
| ring->data = kmalloc(length*ring->buf.bpd, GFP_ATOMIC); |
| ring->read_p = NULL; |
| ring->write_p = NULL; |
| ring->last_written_p = NULL; |
| ring->half_p = NULL; |
| return ring->data ? 0 : -ENOMEM; |
| } |
| |
| static inline void __iio_init_sw_ring_buffer(struct iio_sw_ring_buffer *ring) |
| { |
| spin_lock_init(&ring->use_lock); |
| } |
| |
| static inline void __iio_free_sw_ring_buffer(struct iio_sw_ring_buffer *ring) |
| { |
| kfree(ring->data); |
| } |
| |
| void iio_mark_sw_rb_in_use(struct iio_ring_buffer *r) |
| { |
| struct iio_sw_ring_buffer *ring = iio_to_sw_ring(r); |
| spin_lock(&ring->use_lock); |
| ring->use_count++; |
| spin_unlock(&ring->use_lock); |
| } |
| EXPORT_SYMBOL(iio_mark_sw_rb_in_use); |
| |
| void iio_unmark_sw_rb_in_use(struct iio_ring_buffer *r) |
| { |
| struct iio_sw_ring_buffer *ring = iio_to_sw_ring(r); |
| spin_lock(&ring->use_lock); |
| ring->use_count--; |
| spin_unlock(&ring->use_lock); |
| } |
| EXPORT_SYMBOL(iio_unmark_sw_rb_in_use); |
| |
| |
| /* Ring buffer related functionality */ |
| /* Store to ring is typically called in the bh of a data ready interrupt handler |
| * in the device driver */ |
| /* Lock always held if their is a chance this may be called */ |
| /* Only one of these per ring may run concurrently - enforced by drivers */ |
| static int iio_store_to_sw_ring(struct iio_sw_ring_buffer *ring, |
| unsigned char *data, s64 timestamp) |
| { |
| int ret = 0; |
| int code; |
| unsigned char *temp_ptr, *change_test_ptr; |
| |
| /* initial store */ |
| if (unlikely(ring->write_p == NULL)) { |
| ring->write_p = ring->data; |
| /* Doesn't actually matter if this is out of the set |
| * as long as the read pointer is valid before this |
| * passes it - guaranteed as set later in this function. |
| */ |
| ring->half_p = ring->data - ring->buf.length*ring->buf.bpd/2; |
| } |
| /* Copy data to where ever the current write pointer says */ |
| memcpy(ring->write_p, data, ring->buf.bpd); |
| barrier(); |
| /* Update the pointer used to get most recent value. |
| * Always valid as either points to latest or second latest value. |
| * Before this runs it is null and read attempts fail with -EAGAIN. |
| */ |
| ring->last_written_p = ring->write_p; |
| barrier(); |
| /* temp_ptr used to ensure we never have an invalid pointer |
| * it may be slightly lagging, but never invalid |
| */ |
| temp_ptr = ring->write_p + ring->buf.bpd; |
| /* End of ring, back to the beginning */ |
| if (temp_ptr == ring->data + ring->buf.length*ring->buf.bpd) |
| temp_ptr = ring->data; |
| /* Update the write pointer |
| * always valid as long as this is the only function able to write. |
| * Care needed with smp systems to ensure more than one ring fill |
| * is never scheduled. |
| */ |
| ring->write_p = temp_ptr; |
| |
| if (ring->read_p == NULL) |
| ring->read_p = ring->data; |
| /* Buffer full - move the read pointer and create / escalate |
| * ring event */ |
| /* Tricky case - if the read pointer moves before we adjust it. |
| * Handle by not pushing if it has moved - may result in occasional |
| * unnecessary buffer full events when it wasn't quite true. |
| */ |
| else if (ring->write_p == ring->read_p) { |
| change_test_ptr = ring->read_p; |
| temp_ptr = change_test_ptr + ring->buf.bpd; |
| if (temp_ptr |
| == ring->data + ring->buf.length*ring->buf.bpd) { |
| temp_ptr = ring->data; |
| } |
| /* We are moving pointer on one because the ring is full. Any |
| * change to the read pointer will be this or greater. |
| */ |
| if (change_test_ptr == ring->read_p) |
| ring->read_p = temp_ptr; |
| |
| spin_lock(&ring->buf.shared_ev_pointer.lock); |
| |
| ret = iio_push_or_escallate_ring_event(&ring->buf, |
| IIO_EVENT_CODE_RING_100_FULL, timestamp); |
| spin_unlock(&ring->buf.shared_ev_pointer.lock); |
| if (ret) |
| goto error_ret; |
| } |
| /* investigate if our event barrier has been passed */ |
| /* There are definite 'issues' with this and chances of |
| * simultaneous read */ |
| /* Also need to use loop count to ensure this only happens once */ |
| ring->half_p += ring->buf.bpd; |
| if (ring->half_p == ring->data + ring->buf.length*ring->buf.bpd) |
| ring->half_p = ring->data; |
| if (ring->half_p == ring->read_p) { |
| spin_lock(&ring->buf.shared_ev_pointer.lock); |
| code = IIO_EVENT_CODE_RING_50_FULL; |
| ret = __iio_push_event(&ring->buf.ev_int, |
| code, |
| timestamp, |
| &ring->buf.shared_ev_pointer); |
| spin_unlock(&ring->buf.shared_ev_pointer.lock); |
| } |
| error_ret: |
| return ret; |
| } |
| |
| int iio_rip_sw_rb(struct iio_ring_buffer *r, |
| size_t count, u8 **data, int *dead_offset) |
| { |
| struct iio_sw_ring_buffer *ring = iio_to_sw_ring(r); |
| |
| u8 *initial_read_p, *initial_write_p, *current_read_p, *end_read_p; |
| int ret, max_copied; |
| int bytes_to_rip; |
| |
| /* A userspace program has probably made an error if it tries to |
| * read something that is not a whole number of bpds. |
| * Return an error. |
| */ |
| if (count % ring->buf.bpd) { |
| ret = -EINVAL; |
| printk(KERN_INFO "Ring buffer read request not whole number of" |
| "samples: Request bytes %zd, Current bpd %d\n", |
| count, ring->buf.bpd); |
| goto error_ret; |
| } |
| /* Limit size to whole of ring buffer */ |
| bytes_to_rip = min((size_t)(ring->buf.bpd*ring->buf.length), count); |
| |
| *data = kmalloc(bytes_to_rip, GFP_KERNEL); |
| if (*data == NULL) { |
| ret = -ENOMEM; |
| goto error_ret; |
| } |
| |
| /* build local copy */ |
| initial_read_p = ring->read_p; |
| if (unlikely(initial_read_p == NULL)) { /* No data here as yet */ |
| ret = 0; |
| goto error_free_data_cpy; |
| } |
| |
| initial_write_p = ring->write_p; |
| |
| /* Need a consistent pair */ |
| while ((initial_read_p != ring->read_p) |
| || (initial_write_p != ring->write_p)) { |
| initial_read_p = ring->read_p; |
| initial_write_p = ring->write_p; |
| } |
| if (initial_write_p == initial_read_p) { |
| /* No new data available.*/ |
| ret = 0; |
| goto error_free_data_cpy; |
| } |
| |
| if (initial_write_p >= initial_read_p + bytes_to_rip) { |
| /* write_p is greater than necessary, all is easy */ |
| max_copied = bytes_to_rip; |
| memcpy(*data, initial_read_p, max_copied); |
| end_read_p = initial_read_p + max_copied; |
| } else if (initial_write_p > initial_read_p) { |
| /*not enough data to cpy */ |
| max_copied = initial_write_p - initial_read_p; |
| memcpy(*data, initial_read_p, max_copied); |
| end_read_p = initial_write_p; |
| } else { |
| /* going through 'end' of ring buffer */ |
| max_copied = ring->data |
| + ring->buf.length*ring->buf.bpd - initial_read_p; |
| memcpy(*data, initial_read_p, max_copied); |
| /* possible we are done if we align precisely with end */ |
| if (max_copied == bytes_to_rip) |
| end_read_p = ring->data; |
| else if (initial_write_p |
| > ring->data + bytes_to_rip - max_copied) { |
| /* enough data to finish */ |
| memcpy(*data + max_copied, ring->data, |
| bytes_to_rip - max_copied); |
| max_copied = bytes_to_rip; |
| end_read_p = ring->data + (bytes_to_rip - max_copied); |
| } else { /* not enough data */ |
| memcpy(*data + max_copied, ring->data, |
| initial_write_p - ring->data); |
| max_copied += initial_write_p - ring->data; |
| end_read_p = initial_write_p; |
| } |
| } |
| /* Now to verify which section was cleanly copied - i.e. how far |
| * read pointer has been pushed */ |
| current_read_p = ring->read_p; |
| |
| if (initial_read_p <= current_read_p) |
| *dead_offset = current_read_p - initial_read_p; |
| else |
| *dead_offset = ring->buf.length*ring->buf.bpd |
| - (initial_read_p - current_read_p); |
| |
| /* possible issue if the initial write has been lapped or indeed |
| * the point we were reading to has been passed */ |
| /* No valid data read. |
| * In this case the read pointer is already correct having been |
| * pushed further than we would look. */ |
| if (max_copied - *dead_offset < 0) { |
| ret = 0; |
| goto error_free_data_cpy; |
| } |
| |
| /* setup the next read position */ |
| /* Beware, this may fail due to concurrency fun and games. |
| * Possible that sufficient fill commands have run to push the read |
| * pointer past where we would be after the rip. If this occurs, leave |
| * it be. |
| */ |
| /* Tricky - deal with loops */ |
| |
| while (ring->read_p != end_read_p) |
| ring->read_p = end_read_p; |
| |
| return max_copied - *dead_offset; |
| |
| error_free_data_cpy: |
| kfree(*data); |
| error_ret: |
| return ret; |
| } |
| EXPORT_SYMBOL(iio_rip_sw_rb); |
| |
| int iio_store_to_sw_rb(struct iio_ring_buffer *r, u8 *data, s64 timestamp) |
| { |
| struct iio_sw_ring_buffer *ring = iio_to_sw_ring(r); |
| return iio_store_to_sw_ring(ring, data, timestamp); |
| } |
| EXPORT_SYMBOL(iio_store_to_sw_rb); |
| |
| static int iio_read_last_from_sw_ring(struct iio_sw_ring_buffer *ring, |
| unsigned char *data) |
| { |
| unsigned char *last_written_p_copy; |
| |
| iio_mark_sw_rb_in_use(&ring->buf); |
| again: |
| barrier(); |
| last_written_p_copy = ring->last_written_p; |
| barrier(); /*unnessecary? */ |
| /* Check there is anything here */ |
| if (last_written_p_copy == NULL) |
| return -EAGAIN; |
| memcpy(data, last_written_p_copy, ring->buf.bpd); |
| |
| if (unlikely(ring->last_written_p != last_written_p_copy)) |
| goto again; |
| |
| iio_unmark_sw_rb_in_use(&ring->buf); |
| return 0; |
| } |
| |
| int iio_read_last_from_sw_rb(struct iio_ring_buffer *r, |
| unsigned char *data) |
| { |
| return iio_read_last_from_sw_ring(iio_to_sw_ring(r), data); |
| } |
| EXPORT_SYMBOL(iio_read_last_from_sw_rb); |
| |
| int iio_request_update_sw_rb(struct iio_ring_buffer *r) |
| { |
| int ret = 0; |
| struct iio_sw_ring_buffer *ring = iio_to_sw_ring(r); |
| |
| spin_lock(&ring->use_lock); |
| if (!ring->update_needed) |
| goto error_ret; |
| if (ring->use_count) { |
| ret = -EAGAIN; |
| goto error_ret; |
| } |
| __iio_free_sw_ring_buffer(ring); |
| ret = __iio_allocate_sw_ring_buffer(ring, ring->buf.bpd, |
| ring->buf.length); |
| error_ret: |
| spin_unlock(&ring->use_lock); |
| return ret; |
| } |
| EXPORT_SYMBOL(iio_request_update_sw_rb); |
| |
| int iio_get_bpd_sw_rb(struct iio_ring_buffer *r) |
| { |
| struct iio_sw_ring_buffer *ring = iio_to_sw_ring(r); |
| return ring->buf.bpd; |
| } |
| EXPORT_SYMBOL(iio_get_bpd_sw_rb); |
| |
| int iio_set_bpd_sw_rb(struct iio_ring_buffer *r, size_t bpd) |
| { |
| if (r->bpd != bpd) { |
| r->bpd = bpd; |
| if (r->access.mark_param_change) |
| r->access.mark_param_change(r); |
| } |
| return 0; |
| } |
| EXPORT_SYMBOL(iio_set_bpd_sw_rb); |
| |
| int iio_get_length_sw_rb(struct iio_ring_buffer *r) |
| { |
| return r->length; |
| } |
| EXPORT_SYMBOL(iio_get_length_sw_rb); |
| |
| int iio_set_length_sw_rb(struct iio_ring_buffer *r, int length) |
| { |
| if (r->length != length) { |
| r->length = length; |
| if (r->access.mark_param_change) |
| r->access.mark_param_change(r); |
| } |
| return 0; |
| } |
| EXPORT_SYMBOL(iio_set_length_sw_rb); |
| |
| int iio_mark_update_needed_sw_rb(struct iio_ring_buffer *r) |
| { |
| struct iio_sw_ring_buffer *ring = iio_to_sw_ring(r); |
| ring->update_needed = true; |
| return 0; |
| } |
| EXPORT_SYMBOL(iio_mark_update_needed_sw_rb); |
| |
| static void iio_sw_rb_release(struct device *dev) |
| { |
| struct iio_ring_buffer *r = to_iio_ring_buffer(dev); |
| kfree(iio_to_sw_ring(r)); |
| } |
| |
| static IIO_RING_ENABLE_ATTR; |
| static IIO_RING_BPS_ATTR; |
| static IIO_RING_LENGTH_ATTR; |
| |
| /* Standard set of ring buffer attributes */ |
| static struct attribute *iio_ring_attributes[] = { |
| &dev_attr_length.attr, |
| &dev_attr_bps.attr, |
| &dev_attr_ring_enable.attr, |
| NULL, |
| }; |
| |
| static struct attribute_group iio_ring_attribute_group = { |
| .attrs = iio_ring_attributes, |
| }; |
| |
| static const struct attribute_group *iio_ring_attribute_groups[] = { |
| &iio_ring_attribute_group, |
| NULL |
| }; |
| |
| static struct device_type iio_sw_ring_type = { |
| .release = iio_sw_rb_release, |
| .groups = iio_ring_attribute_groups, |
| }; |
| |
| struct iio_ring_buffer *iio_sw_rb_allocate(struct iio_dev *indio_dev) |
| { |
| struct iio_ring_buffer *buf; |
| struct iio_sw_ring_buffer *ring; |
| |
| ring = kzalloc(sizeof *ring, GFP_KERNEL); |
| if (!ring) |
| return NULL; |
| buf = &ring->buf; |
| iio_ring_buffer_init(buf, indio_dev); |
| __iio_init_sw_ring_buffer(ring); |
| buf->dev.type = &iio_sw_ring_type; |
| device_initialize(&buf->dev); |
| buf->dev.parent = &indio_dev->dev; |
| buf->dev.bus = &iio_bus_type; |
| dev_set_drvdata(&buf->dev, (void *)buf); |
| |
| return buf; |
| } |
| EXPORT_SYMBOL(iio_sw_rb_allocate); |
| |
| void iio_sw_rb_free(struct iio_ring_buffer *r) |
| { |
| if (r) |
| iio_put_ring_buffer(r); |
| } |
| EXPORT_SYMBOL(iio_sw_rb_free); |
| |
| int iio_sw_ring_preenable(struct iio_dev *indio_dev) |
| { |
| size_t size; |
| dev_dbg(&indio_dev->dev, "%s\n", __func__); |
| /* Check if there are any scan elements enabled, if not fail*/ |
| if (!(indio_dev->scan_count || indio_dev->scan_timestamp)) |
| return -EINVAL; |
| if (indio_dev->scan_timestamp) |
| if (indio_dev->scan_count) |
| /* Timestamp (aligned to s64) and data */ |
| size = (((indio_dev->scan_count * indio_dev->ring->bpe) |
| + sizeof(s64) - 1) |
| & ~(sizeof(s64) - 1)) |
| + sizeof(s64); |
| else /* Timestamp only */ |
| size = sizeof(s64); |
| else /* Data only */ |
| size = indio_dev->scan_count * indio_dev->ring->bpe; |
| indio_dev->ring->access.set_bpd(indio_dev->ring, size); |
| |
| return 0; |
| } |
| EXPORT_SYMBOL(iio_sw_ring_preenable); |
| |
| void iio_sw_trigger_bh_to_ring(struct work_struct *work_s) |
| { |
| struct iio_sw_ring_helper_state *st |
| = container_of(work_s, struct iio_sw_ring_helper_state, |
| work_trigger_to_ring); |
| int len = 0; |
| size_t datasize = st->indio_dev |
| ->ring->access.get_bpd(st->indio_dev->ring); |
| char *data = kmalloc(datasize, GFP_KERNEL); |
| |
| if (data == NULL) { |
| dev_err(st->indio_dev->dev.parent, |
| "memory alloc failed in ring bh"); |
| return; |
| } |
| |
| if (st->indio_dev->scan_count) |
| len = st->get_ring_element(st, data); |
| |
| /* Guaranteed to be aligned with 8 byte boundary */ |
| if (st->indio_dev->scan_timestamp) |
| *(s64 *)(((u32)data + len |
| + sizeof(s64) - 1) & ~(sizeof(s64) - 1)) |
| = st->last_timestamp; |
| st->indio_dev->ring->access.store_to(st->indio_dev->ring, |
| (u8 *)data, |
| st->last_timestamp); |
| |
| iio_trigger_notify_done(st->indio_dev->trig); |
| kfree(data); |
| |
| return; |
| } |
| EXPORT_SYMBOL(iio_sw_trigger_bh_to_ring); |
| |
| void iio_sw_poll_func_th(struct iio_dev *indio_dev, s64 time) |
| { struct iio_sw_ring_helper_state *h |
| = iio_dev_get_devdata(indio_dev); |
| h->last_timestamp = time; |
| schedule_work(&h->work_trigger_to_ring); |
| } |
| EXPORT_SYMBOL(iio_sw_poll_func_th); |
| |
| MODULE_DESCRIPTION("Industrialio I/O software ring buffer"); |
| MODULE_LICENSE("GPL"); |