/*
* Intel Wireless WiMAX Connection 2400m
* Generic (non-bus specific) TX handling
*
*
* Copyright (C) 2007-2008 Intel Corporation. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Intel Corporation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*
* Intel Corporation <linux-wimax@intel.com>
* Yanir Lubetkin <yanirx.lubetkin@intel.com>
* - Initial implementation
*
* Intel Corporation <linux-wimax@intel.com>
* Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
* - Rewritten to use a single FIFO to lower the memory allocation
* pressure and optimize cache hits when copying to the queue, as
* well as splitting out bus-specific code.
*
*
* Implements data transmission to the device; this is done through a
* software FIFO, as data/control frames can be coalesced (while the
* device is reading the previous tx transaction, others accumulate).
*
* A FIFO is used because at the end it is resource-cheaper that trying
* to implement scatter/gather over USB. As well, most traffic is going
* to be download (vs upload).
*
* The format for sending/receiving data to/from the i2400m is
* described in detail in rx.c:PROTOCOL FORMAT. In here we implement
* the transmission of that. This is split between a bus-independent
* part that just prepares everything and a bus-specific part that
* does the actual transmission over the bus to the device (in the
* bus-specific driver).
*
*
* The general format of a device-host transaction is MSG-HDR, PLD1,
* PLD2...PLDN, PL1, PL2,...PLN, PADDING.
*
* Because we need the send payload descriptors and then payloads and
* because it is kind of expensive to do scatterlists in USB (one URB
* per node), it becomes cheaper to append all the data to a FIFO
* (copying to a FIFO potentially in cache is cheaper).
*
* Then the bus-specific code takes the parts of that FIFO that are
* written and passes them to the device.
*
* So the concepts to keep in mind there are:
*
* We use a FIFO to queue the data in a linear buffer. We first append
* a MSG-HDR, space for I2400M_TX_PLD_MAX payload descriptors and then
* go appending payloads until we run out of space or of payload
* descriptors. Then we append padding to make the whole transaction a
* multiple of i2400m->bus_tx_block_size (as defined by the bus layer).
*
* - A TX message: a combination of a message header, payload
* descriptors and payloads.
*
* Open: it is marked as active (i2400m->tx_msg is valid) and we
* can keep adding payloads to it.
*
* Closed: we are not appending more payloads to this TX message
* (exahusted space in the queue, too many payloads or
* whichever). We have appended padding so the whole message
* length is aligned to i2400m->bus_tx_block_size (as set by the
* bus/transport layer).
*
* - Most of the time we keep a TX message open to which we append
* payloads.
*
* - If we are going to append and there is no more space (we are at
* the end of the FIFO), we close the message, mark the rest of the
* FIFO space unusable (skip_tail), create a new message at the
* beginning of the FIFO (if there is space) and append the message
* there.
*
* This is because we need to give linear TX messages to the bus
* engine. So we don't write a message to the remaining FIFO space
* until the tail and continue at the head of it.
*
* - We overload one of the fields in the message header to use it as
* 'size' of the TX message, so we can iterate over them. It also
* contains a flag that indicates if we have to skip it or not.
* When we send the buffer, we update that to its real on-the-wire
* value.
*
* - The MSG-HDR PLD1...PLD2 stuff has to be a size multiple of 16.
*
* It follows that if MSG-HDR says we have N messages, the whole
* header + descriptors is 16 + 4*N; for those to be a multiple of
* 16, it follows that N can be 4, 8, 12, ... (32, 48, 64, 80...
* bytes).
*
* So if we have only 1 payload, we have to submit a header that in
* all truth has space for 4.
*
* The implication is that we reserve space for 12 (64 bytes); but
* if we fill up only (eg) 2, our header becomes 32 bytes only. So
* the TX engine has to shift those 32 bytes of msg header and 2
* payloads and padding so that right after it the payloads start
* and the TX engine has to know about that.
*
* It is cheaper to move the header up than the whole payloads down.
*
* We do this in i2400m_tx_close(). See 'i2400m_msg_hdr->offset'.
*
* - Each payload has to be size-padded to 16 bytes; before appending
* it, we just do it.
*
* - The whole message has to be padded to i2400m->bus_tx_block_size;
* we do this at close time. Thus, when reserving space for the
* payload, we always make sure there is also free space for this
* padding that sooner or later will happen.
*
* When we append a message, we tell the bus specific code to kick in
* TXs. It will TX (in parallel) until the buffer is exhausted--hence
* the lockin we do. The TX code will only send a TX message at the
* time (which remember, might contain more than one payload). Of
* course, when the bus-specific driver attempts to TX a message that
* is still open, it gets closed first.
*
* Gee, this is messy; well a picture. In the example below we have a
* partially full FIFO, with a closed message ready to be delivered
* (with a moved message header to make sure it is size-aligned to
* 16), TAIL room that was unusable (and thus is marked with a message
* header that says 'skip this') and at the head of the buffer, an
* incomplete message with a couple of payloads.
*
* N ___________________________________________________
* | |
* | TAIL room |
* | |
* | msg_hdr to skip (size |= 0x80000) |
* |---------------------------------------------------|-------
* | | /|\
* | | |
* | TX message padding | |
* | | |
* | | |
* |- - - - - - - - - - - - - - - - - - - - - - - - - -| |
* | | |
* | payload 1 | |
* | | N * tx_block_size
* | | |
* |- - - - - - - - - - - - - - - - - - - - - - - - - -| |
* | | |
* | payload 1 | |
* | | |
* | | |
* |- - - - - - - - - - - - - - - - - - - - - - - - - -|- -|- - - -
* | padding 3 /|\ | | /|\
* | padding 2 | | | |
* | pld 1 32 bytes (2 * 16) | | |
* | pld 0 | | | |
* | moved msg_hdr \|/ | \|/ |
* |- - - - - - - - - - - - - - - - - - - - - - - - - -|- - - |
* | | _PLD_SIZE
* | unused | |
* | | |
* |- - - - - - - - - - - - - - - - - - - - - - - - - -| |
* | msg_hdr (size X) [this message is closed] | \|/
* |===================================================|========== <=== OUT
* | |
* | |
* | |
* | Free rooom |
* | |
* | |
* | |
* | |
* | |
* | |
* | |
* | |
* | |
* |===================================================|========== <=== IN
* | |
* | |
* | |
* | |
* | payload 1 |
* | |
* | |
* |- - - - - - - - - - - - - - - - - - - - - - - - - -|
* | |
* | payload 0 |
* | |
* | |
* |- - - - - - - - - - - - - - - - - - - - - - - - - -|
* | pld 11 /|\ |
* | ... | |
* | pld 1 64 bytes (2 * 16) |
* | pld 0 | |
* | msg_hdr (size X) \|/ [message is open] |
* 0 ---------------------------------------------------
*
*
* ROADMAP
*
* i2400m_tx_setup() Called by i2400m_setup
* i2400m_tx_release() Called by i2400m_release()
*
* i2400m_tx() Called to send data or control frames
* i2400m_tx_fifo_push() Allocates append-space in the FIFO
* i2400m_tx_new() Opens a new message in the FIFO
* i2400m_tx_fits() Checks if a new payload fits in the message
* i2400m_tx_close() Closes an open message in the FIFO
* i2400m_tx_skip_tail() Marks unusable FIFO tail space
* i2400m->bus_tx_kick()
*
* Now i2400m->bus_tx_kick() is the the bus-specific driver backend
* implementation; that would do:
*
* i2400m->bus_tx_kick()
* i2400m_tx_msg_get() Gets first message ready to go
* ...sends it...
* i2400m_tx_msg_sent() Ack the message is sent; repeat from
* _tx_msg_get() until it returns NULL
* (FIFO empty).
*/
#include <linux/netdevice.h>
#include <linux/slab.h>
#include "i2400m.h"
#define D_SUBMODULE tx
#include "debug-levels.h"
enum {
/**
* TX Buffer size
*
* Doc says maximum transaction is 16KiB. If we had 16KiB en
* route and 16KiB being queued, it boils down to needing
* 32KiB.
* 32KiB is insufficient for 1400 MTU, hence increasing
* tx buffer size to 64KiB.
*/
I2400M_TX_BUF_SIZE = 65536,
/**
* Message header and payload descriptors have to be 16
* aligned (16 + 4 * N = 16 * M). If we take that average sent
* packets are MTU size (~1400-~1500) it follows that we could
* fit at most 10-11 payloads in one transaction. To meet the
* alignment requirement, that means we need to leave space
* for 12 (64 bytes). To simplify, we leave space for that. If
* at the end there are less, we pad up to the nearest
* multiple of 16.
*/
/*
* According to Intel Wimax i3200, i5x50 and i6x50 specification
* documents, the maximum number of payloads per message can be
* up to 60. Increasing the number of payloads to 60 per message
* helps to accommodate smaller payloads in a single transaction.
*/
I2400M_TX_PLD_MAX = 60,
I2400M_TX_PLD_SIZE = sizeof(struct i2400m_msg_hdr)
+ I2400M_TX_PLD_MAX * sizeof(struct i2400m_pld),
I2400M_TX_SKIP = 0x80000000,
/*
* According to Intel Wimax i3200, i5x50 and i6x50 specification
* documents, the maximum size of each message can be up to 16KiB.
*/
I2400M_TX_MSG_SIZE = 16384,
};
#define TAIL_FULL ((void *)~(unsigned long)NULL)
/*
* Calculate how much tail room is available
*
* Note the trick here. This path is ONLY caleed for Case A (see
* i2400m_tx_fifo_push() below), where we have:
*
* Case A
* N ___________
* | tail room |
* | |
* |<- IN ->|
* | |
* | data |
* | |
* |<- OUT ->|
* | |
* | head room |
* 0 -----------
*
* When calculating the tail_room, tx_in might get to be zero if
* i2400m->tx_in is right at the end of the buffer (really full
* buffer) if there is no head room. In this case, tail_room would be
* I2400M_TX_BUF_SIZE, although it is actually zero. Hence the final
* mod (%) operation. However, when doing this kind of optimization,
* i2400m->tx_in being zero would fail, so we treat is an a special
* case.
*/
static inline
size_t __i2400m_tx_tail_room(struct i2400m *i2400m)
{
size_t tail_room;
size_t tx_in;
if (unlikely(i2400m->tx_in == 0))
return I2400M_TX_BUF_SIZE;
tx_in = i2400m->tx_in % I2400M_TX_BUF_SIZE;
tail_room = I2400M_TX_BUF_SIZE - tx_in;
tail_room %= I2400M_TX_BUF_SIZE;
return tail_room;
}
/*
* Allocate @size bytes in the TX fifo, return a pointer to it
*
* @i2400m: device descriptor
* @size: size of the buffer we need to allocate
* @padding: ensure that there is at least this many bytes of free
* contiguous space in the fifo. This is needed because later on
* we might need to add padding.
* @try_head: specify either to allocate head room or tail room space
* in the TX FIFO. This boolean is required to avoids a system hang
* due to an infinite loop caused by i2400m_tx_fifo_push().
* The caller must always try to allocate tail room space first by
* calling this routine with try_head = 0. In case if there
* is not enough tail room space but there is enough head room space,
* (i2400m_tx_fifo_push() returns TAIL_FULL) try to allocate head
* room space, by calling this routine again with try_head = 1.
*
* Returns:
*
* Pointer to the allocated space. NULL if there is no
* space. TAIL_FULL if there is no space at the tail but there is at
* the head (Case B below).
*
* These are the two basic cases we need to keep an eye for -- it is
* much better explained in linux/kernel/kfifo.c, but this code
* basically does the same. No rocket science here.
*
* Case A Case B
* N ___________ ___________
* | tail room | | data |
* | | | |
* |<- IN ->| |<- OUT ->|
* | | | |
* | data | | room |
* | | | |
* |<- OUT ->| |<- IN ->|
* | | | |
* | head room | | data |
* 0 ----------- -----------
*
* We allocate only *contiguous* space.
*
* We can allocate only from 'room'. In Case B, it is simple; in case
* A, we only try from the tail room; if it is not enough, we just
* fail and return TAIL_FULL and let the caller figure out if we wants to
* skip the tail room and try to allocate from the head.
*
* There is a corner case, wherein i2400m_tx_new() can get into
* an infinite loop calling i2400m_tx_fifo_push().
* In certain situations, tx_in would have reached on the top of TX FIFO
* and i2400m_tx_tail_room() returns 0, as described below:
*
* N ___________ tail room is zero
* |<- IN ->|
* | |
* | |
* | |
* | data |
* |<- OUT ->|
* | |
* | |
* | head room |
* 0 -----------
* During such a time, where tail room is zero in the TX FIFO and if there
* is a request to add a payload to TX FIFO, which calls:
* i2400m_tx()
* ->calls i2400m_tx_close()
* ->calls i2400m_tx_skip_tail()
* goto try_new;
* ->calls i2400m_tx_new()
* |----> [try_head:]
* infinite loop | ->calls i2400m_tx_fifo_push()
* | if (tail_room < needed)
* | if (head_room => needed)
* | return TAIL_FULL;
* |<---- goto try_head;
*
* i2400m_tx() calls i2400m_tx_close() to close the message, since there
* is no tail room to accommodate the payload and calls
* i2400m_tx_skip_tail() to skip the tail space. Now i2400m_tx() calls
* i2400m_tx_new() to allocate space for new message header calling
* i2400m_tx_fifo_push() that returns TAIL_FULL, since there is no tail space
* to accommodate the message header, but there is enough head space.
* The i2400m_tx_new() keeps re-retrying by calling i2400m_tx_fifo_push()
* ending up in a loop causing system freeze.
*
* This corner case is avoided by using a try_head boolean,
* as an argument to i2400m_tx_fifo_push().
*
* Note:
*
* Assumes i2400m->tx_lock is taken, and we use that as a barrier
*
* The indexes keep increasing and we reset them to zero when we
* pop data off the queue
*/
static
void *i2400m_tx_fifo_push(struct i2400m *i2400m, size_t size,
size_t padding, bool try_head)
{
struct device *dev = i2400m_dev(i2400m);
size_t room, tail_room, needed_size;
void *ptr;
needed_size = size + padding;
room = I2400M_TX_BUF_SIZE - (i2400m->tx_in - i2400m->tx_out);
if (room < needed_size) { /* this takes care of Case B */
d_printf(2, dev, "fifo push %zu/%zu: no space\n",
size, padding);
return NULL;
}
/* Is there space at the tail? */
tail_room = __i2400m_tx_tail_room(i2400m);
if (!try_head && tail_room < needed_size) {
/*
* If the tail room space is not enough to push the message
* in the TX FIFO, then there are two possibilities:
* 1. There is enough head room space to accommodate
* this message in the TX FIFO.
* 2. There is not enough space in the head room and
* in tail room of the TX FIFO to accommodate the message.
* In the case (1), return TAIL_FULL so that the caller
* can figure out, if the caller wants to push the message
* into the head room space.
* In the case (2), return NULL, indicating that the TX FIFO
* cannot accommodate the message.
*/
if (room - tail_room >= needed_size) {
d_printf(2, dev, "fifo push %zu/%zu: tail full\n",
size, padding);
return TAIL_FULL; /* There might be head space */
} else {
d_printf(2, dev, "fifo push %zu/%zu: no head space\n",
size, padding);
return NULL; /* There is no space */
}
}
ptr = i2400m->tx_buf + i2400m->tx_in % I2400M_TX_BUF_SIZE;
d_printf(2, dev, "fifo push %zu/%zu: at @%zu\n", size, padding,
i2400m->tx_in % I2400M_TX_BUF_SIZE);
i2400m->tx_in += size;
return ptr;
}
/*
* Mark the tail of the FIFO buffer as 'to-skip'
*
* We should never hit the BUG_ON() because all the sizes we push to
* the FIFO are padded to be a multiple of 16 -- the size of *msg
* (I2400M_PL_PAD for the payloads, I2400M_TX_PLD_SIZE for the
* header).
*
* Tail room can get to be zero if a message was opened when there was
* space only for a header. _tx_close() will mark it as to-skip (as it
* will have no payloads) and there will be no more space to flush, so
* nothing has to be done here. This is probably cheaper than ensuring
* in _tx_new() that there is some space for payloads...as we could
* always possibly hit the same problem if the payload wouldn't fit.
*
* Note:
*
* Assumes i2400m->tx_lock is taken, and we use that as a barrier
*
* This path is only taken for Case A FIFO situations [see
* i2400m_tx_fifo_push()]
*/
static
void i2400m_tx_skip_tail(struct i2400m *i2400m)
{
struct device *dev = i2400m_dev(i2400m);
size_t tx_in = i2400m->tx_in % I2400M_TX_BUF_SIZE;
size_t tail_room = __i2400m_tx_tail_room(i2400m);
struct i2400m_msg_hdr *msg = i2400m->tx_buf + tx_in;
if (unlikely(tail_room == 0))
return;
BUG_ON(tail_room < sizeof(*msg));
msg->size = tail_room | I2400M_TX_SKIP;
d_printf(2, dev, "skip tail: skipping %zu bytes @%zu\n",
tail_room, tx_in);
i2400m->tx_in += tail_room;
}
/*
* Check if a skb will fit in the TX queue's current active TX
* message (if there are still descriptors left unused).
*
* Returns:
* 0 if the message won't fit, 1 if it will.
*
* Note:
*
* Assumes a TX message is active (i2400m->tx_msg).
*
* Assumes i2400m->tx_lock is taken, and we use that as a barrier
*/
static
unsigned i2400m_tx_fits(struct i2400m *i2400m)
{
struct i2400m_msg_hdr *msg_hdr = i2400m->tx_msg;
return le16_to_cpu(msg_hdr->num_pls) < I2400M_TX_PLD_MAX;
}
/*
* Start a new TX message header in the queue.
*
* Reserve memory from the base FIFO engine and then just initialize
* the message header.
*
* We allocate the biggest TX message header we might need (one that'd
* fit I2400M_TX_PLD_MAX payloads) -- when it is closed it will be
* 'ironed it out' and the unneeded parts removed.
*
* NOTE:
*
* Assumes that the previous message is CLOSED (eg: either
* there was none or 'i2400m_tx_close()' was called on it).
*
* Assumes i2400m->tx_lock is taken, and we use that as a barrier
*/
static
void i2400m_tx_new(struct i2400m *i2400m)
{
struct device *dev = i2400m_dev(i2400m);
struct i2400m_msg_hdr *tx_msg;
bool try_head = 0;
BUG_ON(i2400m->tx_msg != NULL);
/*
* In certain situations, TX queue might have enough space to
* accommodate the new message header I2400M_TX_PLD_SIZE, but
* might not have enough space to accommodate the payloads.
* Adding bus_tx_room_min padding while allocating a new TX message
* increases the possibilities of including at least one payload of the
* size <= bus_tx_room_min.
*/
try_head:
tx_msg = i2400m_tx_fifo_push(i2400m, I2400M_TX_PLD_SIZE,
i2400m->bus_tx_room_min, try_head);
if (tx_msg == NULL)
goto out;
else if (tx_msg == TAIL_FULL) {
i2400m_tx_skip_tail(i2400m);
d_printf(2, dev, "new TX message: tail full, trying head\n");
try_head = 1;
goto try_head;
}
memset(tx_msg, 0, I2400M_TX_PLD_SIZE);
tx_msg->size = I2400M_TX_PLD_SIZE;
out:
i2400m->tx_msg = tx_msg;
d_printf(2, dev, "new TX message: %p @%zu\n",
tx_msg, (void *) tx_msg - i2400m->tx_buf);
}
/*
* Finalize the current TX message header
*
* Sets the message header to be at the proper location depending on
* how many descriptors we have (check documentation at the file's
* header for more info on that).
*
* Appends padding bytes to make sure the whole TX message (counting
* from the 'relocated' message header) is aligned to
* tx_block_size. We assume the _append() code has left enough space
* in the FIFO for that. If there are no payloads, just pass, as it
* won't be transferred.
*
* The amount of padding bytes depends on how many payloads are in the
* TX message, as the "msg header and payload descriptors" will be
* shifted up in the buffer.
*/
static
void i2400m_tx_close(struct i2400m *i2400m)
{
struct device *dev = i2400m_dev(i2400m);
struct i2400m_msg_hdr *tx_msg = i2400m->tx_msg;
struct i2400m_msg_hdr *tx_msg_moved;
size_t aligned_size, padding, hdr_size;
void *pad_buf;
unsigned num_pls;
if (tx_msg->size & I2400M_TX_SKIP) /* a skipper? nothing to do */
goto out;
num_pls = le16_to_cpu(tx_msg->num_pls);
/* We can get this situation when a new message was started
* and there was no space to add payloads before hitting the
tail (and taking padding into consideration). */
if (num_pls == 0) {
tx_msg->size |= I2400M_TX_SKIP;
goto out;
}
/* Relocate the message header
*
* Find the current header size, align it to 16 and if we need
* to move it so the tail is next to the payloads, move it and
* set the offset.
*
* If it moved, this header is good only for transmission; the
* original one (it is kept if we moved) is still used to
* figure out where the next TX message starts (and where the
* offset to the moved header is).
*/
hdr_size = sizeof(*tx_msg)
+ le16_to_cpu(tx_msg->num_pls) * sizeof(tx_msg->pld[0]);
hdr_size = ALIGN(hdr_size, I2400M_PL_ALIGN);
tx_msg->offset = I2400M_TX_PLD_SIZE - hdr_size;
tx_msg_moved = (void *) tx_msg + tx_msg->offset;
memmove(tx_msg_moved, tx_msg, hdr_size);
tx_msg_moved->size -= tx_msg->offset;
/*
* Now figure out how much we have to add to the (moved!)
* message so the size is a multiple of i2400m->bus_tx_block_size.
*/
aligned_size = ALIGN(tx_msg_moved->size, i2400m->bus_tx_block_size);
padding = aligned_size - tx_msg_moved->size;
if (padding > 0) {
pad_buf = i2400m_tx_fifo_push(i2400m, padding, 0, 0);
if (unlikely(WARN_ON(pad_buf == NULL
|| pad_buf == TAIL_FULL))) {
/* This should not happen -- append should verify
* there is always space left at least to append
* tx_block_size */
dev_err(dev,
"SW BUG! Possible data leakage from memory the "
"device should not read for padding - "
"size %lu aligned_size %zu tx_buf %p in "
"%zu out %zu\n",
(unsigned long) tx_msg_moved->size,
aligned_size, i2400m->tx_buf, i2400m->tx_in,
i2400m->tx_out);
} else
memset(pad_buf, 0xad, padding);
}
tx_msg_moved->padding = cpu_to_le16(padding);
tx_msg_moved->size += padding;
if (tx_msg != tx_msg_moved)
tx_msg->size += padding;
out:
i2400m->tx_msg = NULL;
}
/**
* i2400m_tx - send the data in a buffer to the device
*
* @buf: pointer to the buffer to transmit
*
* @buf_len: buffer size
*
* @pl_type: type of the payload we are sending.
*
* Returns:
* 0 if ok, < 0 errno code on error (-ENOSPC, if there is no more
* room for the message in the queue).
*
* Appends the buffer to the TX FIFO and notifies the bus-specific
* part of the driver that there is new data ready to transmit.
* Once this function returns, the buffer has been copied, so it can
* be reused.
*
* The steps followed to append are explained in detail in the file
* header.
*
* Whenever we write to a message, we increase msg->size, so it
* reflects exactly how big the message is. This is needed so that if
* we concatenate two messages before they can be sent, the code that
* sends the messages can find the boundaries (and it will replace the
* size with the real barker before sending).
*
* Note:
*
* Cold and warm reset payloads need to be sent as a single
* payload, so we handle that.
*/
int i2400m_tx(struct i2400m *i2400m, const void *buf, size_t buf_len,
enum i2400m_pt pl_type)
{
int result = -ENOSPC;
struct device *dev = i2400m_dev(i2400m);
unsigned long flags;
size_t padded_len;
void *ptr;
bool try_head = 0;
unsigned is_singleton = pl_type == I2400M_PT_RESET_WARM
|| pl_type == I2400M_PT_RESET_COLD;
d_fnstart(3, dev, "(i2400m %p skb %p [%zu bytes] pt %u)\n",
i2400m, buf, buf_len, pl_type);
padded_len = ALIGN(buf_len, I2400M_PL_ALIGN);
d_printf(5, dev, "padded_len %zd buf_len %zd\n", padded_len, buf_len);
/* If there is no current TX message, create one; if the
* current one is out of payload slots or we have a singleton,
* close it and start a new one */
spin_lock_irqsave(&i2400m->tx_lock, flags);
/* If tx_buf is NULL, device is shutdown */
if (i2400m->tx_buf == NULL) {
result = -ESHUTDOWN;
goto error_tx_new;
}
try_new:
if (unlikely(i2400m->tx_msg == NULL))
i2400m_tx_new(i2400m);
else if (unlikely(!i2400m_tx_fits(i2400m)
|| (is_singleton && i2400m->tx_msg->num_pls != 0))) {
d_printf(2, dev, "closing TX message (fits %u singleton "
"%u num_pls %u)\n", i2400m_tx_fits(i2400m),
is_singleton, i2400m->tx_msg->num_pls);
i2400m_tx_close(i2400m);
i2400m_tx_new(i2400m);
}
if (i2400m->tx_msg == NULL)
goto error_tx_new;
/*
* Check if this skb will fit in the TX queue's current active
* TX message. The total message size must not exceed the maximum
* size of each message I2400M_TX_MSG_SIZE. If it exceeds,
* close the current message and push this skb into the new message.
*/
if (i2400m->tx_msg->size + padded_len > I2400M_TX_MSG_SIZE) {
d_printf(2, dev, "TX: message too big, going new\n");
i2400m_tx_close(i2400m);
i2400m_tx_new(i2400m);
}
if (i2400m->tx_msg == NULL)
goto error_tx_new;
/* So we have a current message header; now append space for
* the message -- if there is not enough, try the head */
ptr = i2400m_tx_fifo_push(i2400m, padded_len,
i2400m->bus_tx_block_size, try_head);
if (ptr == TAIL_FULL) { /* Tail is full, try head */
d_printf(2, dev, "pl append: tail full\n");
i2400m_tx_close(i2400m);
i2400m_tx_skip_tail(i2400m);
try_head = 1;
goto try_new;
} else if (ptr == NULL) { /* All full */
result = -ENOSPC;
d_printf(2, dev, "pl append: all full\n");
} else { /* Got space, copy it, set padding */
struct i2400m_msg_hdr *tx_msg = i2400m->tx_msg;
unsigned num_pls = le16_to_cpu(tx_msg->num_pls);
memcpy(ptr, buf, buf_len);
memset(ptr + buf_len, 0xad, padded_len - buf_len);
i2400m_pld_set(&tx_msg->pld[num_pls], buf_len, pl_type);
d_printf(3, dev, "pld 0x%08x (type 0x%1x len 0x%04zx\n",
le32_to_cpu(tx_msg->pld[num_pls].val),
pl_type, buf_len);
tx_msg->num_pls = le16_to_cpu(num_pls+1);
tx_msg->size += padded_len;
d_printf(2, dev, "TX: appended %zu b (up to %u b) pl #%u\n",
padded_len, tx_msg->size, num_pls+1);
d_printf(2, dev,
"TX: appended hdr @%zu %zu b pl #%u @%zu %zu/%zu b\n",
(void *)tx_msg - i2400m->tx_buf, (size_t)tx_msg->size,
num_pls+1, ptr - i2400m->tx_buf, buf_len, padded_len);
result = 0;
if (is_singleton)
i2400m_tx_close(i2400m);
}
error_tx_new:
spin_unlock_irqrestore(&i2400m->tx_lock, flags);
/* kick in most cases, except when the TX subsys is down, as
* it might free space */
if (likely(result != -ESHUTDOWN))
i2400m->bus_tx_kick(i2400m);
d_fnend(3, dev, "(i2400m %p skb %p [%zu bytes] pt %u) = %d\n",
i2400m, buf, buf_len, pl_type, result);
return result;
}
EXPORT_SYMBOL_GPL(i2400m_tx);
/**
* i2400m_tx_msg_get - Get the first TX message in the FIFO to start sending it
*
* @i2400m: device descriptors
* @bus_size: where to place the size of the TX message
*
* Called by the bus-specific driver to get the first TX message at
* the FIF that is ready for transmission.
*
* It sets the state in @i2400m to indicate the bus-specific driver is
* transferring that message (i2400m->tx_msg_size).
*
* Once the transfer is completed, call i2400m_tx_msg_sent().
*
* Notes:
*
* The size of the TX message to be transmitted might be smaller than
* that of the TX message in the FIFO (in case the header was
* shorter). Hence, we copy it in @bus_size, for the bus layer to
* use. We keep the message's size in i2400m->tx_msg_size so that
* when the bus later is done transferring we know how much to
* advance the fifo.
*
* We collect statistics here as all the data is available and we
* assume it is going to work [see i2400m_tx_msg_sent()].
*/
struct i2400m_msg_hdr *i2400m_tx_msg_get(struct i2400m *i2400m,
size_t *bus_size)
{
struct device *dev = i2400m_dev(i2400m);
struct i2400m_msg_hdr *tx_msg, *tx_msg_moved;
unsigned long flags, pls;
d_fnstart(3, dev, "(i2400m %p bus_size %p)\n", i2400m, bus_size);
spin_lock_irqsave(&i2400m->tx_lock, flags);
tx_msg_moved = NULL;
if (i2400m->tx_buf == NULL)
goto out_unlock;
skip:
tx_msg_moved = NULL;
if (i2400m->tx_in == i2400m->tx_out) { /* Empty FIFO? */
i2400m->tx_in = 0;
i2400m->tx_out = 0;
d_printf(2, dev, "TX: FIFO empty: resetting\n");
goto out_unlock;
}
tx_msg = i2400m->tx_buf + i2400m->tx_out % I2400M_TX_BUF_SIZE;
if (tx_msg->size & I2400M_TX_SKIP) { /* skip? */
d_printf(2, dev, "TX: skip: msg @%zu (%zu b)\n",
i2400m->tx_out % I2400M_TX_BUF_SIZE,
(size_t) tx_msg->size & ~I2400M_TX_SKIP);
i2400m->tx_out += tx_msg->size & ~I2400M_TX_SKIP;
goto skip;
}
if (tx_msg->num_pls == 0) { /* No payloads? */
if (tx_msg == i2400m->tx_msg) { /* open, we are done */
d_printf(2, dev,
"TX: FIFO empty: open msg w/o payloads @%zu\n",
(void *) tx_msg - i2400m->tx_buf);
tx_msg = NULL;
goto out_unlock;
} else { /* closed, skip it */
d_printf(2, dev,
"TX: skip msg w/o payloads @%zu (%zu b)\n",
(void *) tx_msg - i2400m->tx_buf,
(size_t) tx_msg->size);
i2400m->tx_out += tx_msg->size & ~I2400M_TX_SKIP;
goto skip;
}
}
if (tx_msg == i2400m->tx_msg) /* open msg? */
i2400m_tx_close(i2400m);
/* Now we have a valid TX message (with payloads) to TX */
tx_msg_moved = (void *) tx_msg + tx_msg->offset;
i2400m->tx_msg_size = tx_msg->size;
*bus_size = tx_msg_moved->size;
d_printf(2, dev, "TX: pid %d msg hdr at @%zu offset +@%zu "
"size %zu bus_size %zu\n",
current->pid, (void *) tx_msg - i2400m->tx_buf,
(size_t) tx_msg->offset, (size_t) tx_msg->size,
(size_t) tx_msg_moved->size);
tx_msg_moved->barker = le32_to_cpu(I2400M_H2D_PREVIEW_BARKER);
tx_msg_moved->sequence = le32_to_cpu(i2400m->tx_sequence++);
pls = le32_to_cpu(tx_msg_moved->num_pls);
i2400m->tx_pl_num += pls; /* Update stats */
if (pls > i2400m->tx_pl_max)
i2400m->tx_pl_max = pls;
if (pls < i2400m->tx_pl_min)
i2400m->tx_pl_min = pls;
i2400m->tx_num++;
i2400m->tx_size_acc += *bus_size;
if (*bus_size < i2400m->tx_size_min)
i2400m->tx_size_min = *bus_size;
if (*bus_size > i2400m->tx_size_max)
i2400m->tx_size_max = *bus_size;
out_unlock:
spin_unlock_irqrestore(&i2400m->tx_lock, flags);
d_fnstart(3, dev, "(i2400m %p bus_size %p [%zu]) = %p\n",
i2400m, bus_size, *bus_size, tx_msg_moved);
return tx_msg_moved;
}
EXPORT_SYMBOL_GPL(i2400m_tx_msg_get);
/**
* i2400m_tx_msg_sent - indicate the transmission of a TX message
*
* @i2400m: device descriptor
*
* Called by the bus-specific driver when a message has been sent;
* this pops it from the FIFO; and as there is space, start the queue
* in case it was stopped.
*
* Should be called even if the message send failed and we are
* dropping this TX message.
*/
void i2400m_tx_msg_sent(struct i2400m *i2400m)
{
unsigned n;
unsigned long flags;
struct device *dev = i2400m_dev(i2400m);
d_fnstart(3, dev, "(i2400m %p)\n", i2400m);
spin_lock_irqsave(&i2400m->tx_lock, flags);
if (i2400m->tx_buf == NULL)
goto out_unlock;
i2400m->tx_out += i2400m->tx_msg_size;
d_printf(2, dev, "TX: sent %zu b\n", (size_t) i2400m->tx_msg_size);
i2400m->tx_msg_size = 0;
BUG_ON(i2400m->tx_out > i2400m->tx_in);
/* level them FIFO markers off */
n = i2400m->tx_out / I2400M_TX_BUF_SIZE;
i2400m->tx_out %= I2400M_TX_BUF_SIZE;
i2400m->tx_in -= n * I2400M_TX_BUF_SIZE;
out_unlock:
spin_unlock_irqrestore(&i2400m->tx_lock, flags);
d_fnend(3, dev, "(i2400m %p) = void\n", i2400m);
}
EXPORT_SYMBOL_GPL(i2400m_tx_msg_sent);
/**
* i2400m_tx_setup - Initialize the TX queue and infrastructure
*
* Make sure we reset the TX sequence to zero, as when this function
* is called, the firmware has been just restarted. Same rational
* for tx_in, tx_out, tx_msg_size and tx_msg. We reset them since
* the memory for TX queue is reallocated.
*/
int i2400m_tx_setup(struct i2400m *i2400m)
{
int result = 0;
void *tx_buf;
unsigned long flags;
/* Do this here only once -- can't do on
* i2400m_hard_start_xmit() as we'll cause race conditions if
* the WS was scheduled on another CPU */
INIT_WORK(&i2400m->wake_tx_ws, i2400m_wake_tx_work);
tx_buf = kmalloc(I2400M_TX_BUF_SIZE, GFP_ATOMIC);
if (tx_buf == NULL) {
result = -ENOMEM;
goto error_kmalloc;
}
/*
* Fail the build if we can't fit at least two maximum size messages
* on the TX FIFO [one being delivered while one is constructed].
*/
BUILD_BUG_ON(2 * I2400M_TX_MSG_SIZE > I2400M_TX_BUF_SIZE);
spin_lock_irqsave(&i2400m->tx_lock, flags);
i2400m->tx_sequence = 0;
i2400m->tx_in = 0;
i2400m->tx_out = 0;
i2400m->tx_msg_size = 0;
i2400m->tx_msg = NULL;
i2400m->tx_buf = tx_buf;
spin_unlock_irqrestore(&i2400m->tx_lock, flags);
/* Huh? the bus layer has to define this... */
BUG_ON(i2400m->bus_tx_block_size == 0);
error_kmalloc:
return result;
}
/**
* i2400m_tx_release - Tear down the TX queue and infrastructure
*/
void i2400m_tx_release(struct i2400m *i2400m)
{
unsigned long flags;
spin_lock_irqsave(&i2400m->tx_lock, flags);
kfree(i2400m->tx_buf);
i2400m->tx_buf = NULL;
spin_unlock_irqrestore(&i2400m->tx_lock, flags);
}