diff options
| -rw-r--r-- | drivers/net/wimax/i2400m/rx.c | 534 | ||||
| -rw-r--r-- | drivers/net/wimax/i2400m/tx.c | 817 |
2 files changed, 1351 insertions, 0 deletions
diff --git a/drivers/net/wimax/i2400m/rx.c b/drivers/net/wimax/i2400m/rx.c new file mode 100644 index 00000000000..6922022710a --- /dev/null +++ b/drivers/net/wimax/i2400m/rx.c @@ -0,0 +1,534 @@ +/* + * Intel Wireless WiMAX Connection 2400m + * Handle incoming traffic and deliver it to the control or data planes + * + * + * 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 + * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com> + * - Use skb_clone(), break up processing in chunks + * - Split transport/device specific + * - Make buffer size dynamic to exert less memory pressure + * + * + * This handles the RX path. + * + * We receive an RX message from the bus-specific driver, which + * contains one or more payloads that have potentially different + * destinataries (data or control paths). + * + * So we just take that payload from the transport specific code in + * the form of an skb, break it up in chunks (a cloned skb each in the + * case of network packets) and pass it to netdev or to the + * command/ack handler (and from there to the WiMAX stack). + * + * PROTOCOL FORMAT + * + * The format of the buffer is: + * + * HEADER (struct i2400m_msg_hdr) + * PAYLOAD DESCRIPTOR 0 (struct i2400m_pld) + * PAYLOAD DESCRIPTOR 1 + * ... + * PAYLOAD DESCRIPTOR N + * PAYLOAD 0 (raw bytes) + * PAYLOAD 1 + * ... + * PAYLOAD N + * + * See tx.c for a deeper description on alignment requirements and + * other fun facts of it. + * + * ROADMAP + * + * i2400m_rx + * i2400m_rx_msg_hdr_check + * i2400m_rx_pl_descr_check + * i2400m_rx_payload + * i2400m_net_rx + * i2400m_rx_ctl + * i2400m_msg_size_check + * i2400m_report_hook_work [in a workqueue] + * i2400m_report_hook + * wimax_msg_to_user + * i2400m_rx_ctl_ack + * wimax_msg_to_user_alloc + * i2400m_rx_trace + * i2400m_msg_size_check + * wimax_msg + */ +#include <linux/kernel.h> +#include <linux/if_arp.h> +#include <linux/netdevice.h> +#include <linux/workqueue.h> +#include "i2400m.h" + + +#define D_SUBMODULE rx +#include "debug-levels.h" + +struct i2400m_report_hook_args { + struct sk_buff *skb_rx; + const struct i2400m_l3l4_hdr *l3l4_hdr; + size_t size; +}; + + +/* + * Execute i2400m_report_hook in a workqueue + * + * Unpacks arguments from the deferred call, executes it and then + * drops the references. + * + * Obvious NOTE: References are needed because we are a separate + * thread; otherwise the buffer changes under us because it is + * released by the original caller. + */ +static +void i2400m_report_hook_work(struct work_struct *ws) +{ + struct i2400m_work *iw = + container_of(ws, struct i2400m_work, ws); + struct i2400m_report_hook_args *args = (void *) iw->pl; + i2400m_report_hook(iw->i2400m, args->l3l4_hdr, args->size); + kfree_skb(args->skb_rx); + i2400m_put(iw->i2400m); + kfree(iw); +} + + +/* + * Process an ack to a command + * + * @i2400m: device descriptor + * @payload: pointer to message + * @size: size of the message + * + * Pass the acknodledgment (in an skb) to the thread that is waiting + * for it in i2400m->msg_completion. + * + * We need to coordinate properly with the thread waiting for the + * ack. Check if it is waiting or if it is gone. We loose the spinlock + * to avoid allocating on atomic contexts (yeah, could use GFP_ATOMIC, + * but this is not so speed critical). + */ +static +void i2400m_rx_ctl_ack(struct i2400m *i2400m, + const void *payload, size_t size) +{ + struct device *dev = i2400m_dev(i2400m); + struct wimax_dev *wimax_dev = &i2400m->wimax_dev; + unsigned long flags; + struct sk_buff *ack_skb; + + /* Anyone waiting for an answer? */ + spin_lock_irqsave(&i2400m->rx_lock, flags); + if (i2400m->ack_skb != ERR_PTR(-EINPROGRESS)) { + dev_err(dev, "Huh? reply to command with no waiters\n"); + goto error_no_waiter; + } + spin_unlock_irqrestore(&i2400m->rx_lock, flags); + + ack_skb = wimax_msg_alloc(wimax_dev, NULL, payload, size, GFP_KERNEL); + + /* Check waiter didn't time out waiting for the answer... */ + spin_lock_irqsave(&i2400m->rx_lock, flags); + if (i2400m->ack_skb != ERR_PTR(-EINPROGRESS)) { + d_printf(1, dev, "Huh? waiter for command reply cancelled\n"); + goto error_waiter_cancelled; + } + if (ack_skb == NULL) { + dev_err(dev, "CMD/GET/SET ack: cannot allocate SKB\n"); + i2400m->ack_skb = ERR_PTR(-ENOMEM); + } else + i2400m->ack_skb = ack_skb; + spin_unlock_irqrestore(&i2400m->rx_lock, flags); + complete(&i2400m->msg_completion); + return; + +error_waiter_cancelled: + if (ack_skb) + kfree_skb(ack_skb); +error_no_waiter: + spin_unlock_irqrestore(&i2400m->rx_lock, flags); + return; +} + + +/* + * Receive and process a control payload + * + * @i2400m: device descriptor + * @skb_rx: skb that contains the payload (for reference counting) + * @payload: pointer to message + * @size: size of the message + * + * There are two types of control RX messages: reports (asynchronous, + * like your every day interrupts) and 'acks' (reponses to a command, + * get or set request). + * + * If it is a report, we run hooks on it (to extract information for + * things we need to do in the driver) and then pass it over to the + * WiMAX stack to send it to user space. + * + * NOTE: report processing is done in a workqueue specific to the + * generic driver, to avoid deadlocks in the system. + * + * If it is not a report, it is an ack to a previously executed + * command, set or get, so wake up whoever is waiting for it from + * i2400m_msg_to_dev(). i2400m_rx_ctl_ack() takes care of that. + * + * Note that the sizes we pass to other functions from here are the + * sizes of the _l3l4_hdr + payload, not full buffer sizes, as we have + * verified in _msg_size_check() that they are congruent. + * + * For reports: We can't clone the original skb where the data is + * because we need to send this up via netlink; netlink has to add + * headers and we can't overwrite what's preceeding the payload...as + * it is another message. So we just dup them. + */ +static +void i2400m_rx_ctl(struct i2400m *i2400m, struct sk_buff *skb_rx, + const void *payload, size_t size) +{ + int result; + struct device *dev = i2400m_dev(i2400m); + const struct i2400m_l3l4_hdr *l3l4_hdr = payload; + unsigned msg_type; + + result = i2400m_msg_size_check(i2400m, l3l4_hdr, size); + if (result < 0) { + dev_err(dev, "HW BUG? device sent a bad message: %d\n", + result); + goto error_check; + } + msg_type = le16_to_cpu(l3l4_hdr->type); + d_printf(1, dev, "%s 0x%04x: %zu bytes\n", + msg_type & I2400M_MT_REPORT_MASK ? "REPORT" : "CMD/SET/GET", + msg_type, size); + d_dump(2, dev, l3l4_hdr, size); + if (msg_type & I2400M_MT_REPORT_MASK) { + /* These hooks have to be ran serialized; as well, the + * handling might force the execution of commands, and + * that might cause reentrancy issues with + * bus-specific subdrivers and workqueues. So we run + * it in a separate workqueue. */ + struct i2400m_report_hook_args args = { + .skb_rx = skb_rx, + .l3l4_hdr = l3l4_hdr, + .size = size + }; + if (unlikely(i2400m->ready == 0)) /* only send if up */ + return; + skb_get(skb_rx); + i2400m_queue_work(i2400m, i2400m_report_hook_work, + GFP_KERNEL, &args, sizeof(args)); + result = wimax_msg(&i2400m->wimax_dev, NULL, l3l4_hdr, size, + GFP_KERNEL); + if (result < 0) + dev_err(dev, "error sending report to userspace: %d\n", + result); + } else /* an ack to a CMD, GET or SET */ + i2400m_rx_ctl_ack(i2400m, payload, size); +error_check: + return; +} + + + + +/* + * Receive and send up a trace + * + * @i2400m: device descriptor + * @skb_rx: skb that contains the trace (for reference counting) + * @payload: pointer to trace message inside the skb + * @size: size of the message + * + * THe i2400m might produce trace information (diagnostics) and we + * send them through a different kernel-to-user pipe (to avoid + * clogging it). + * + * As in i2400m_rx_ctl(), we can't clone the original skb where the + * data is because we need to send this up via netlink; netlink has to + * add headers and we can't overwrite what's preceeding the + * payload...as it is another message. So we just dup them. + */ +static +void i2400m_rx_trace(struct i2400m *i2400m, + const void *payload, size_t size) +{ + int result; + struct device *dev = i2400m_dev(i2400m); + struct wimax_dev *wimax_dev = &i2400m->wimax_dev; + const struct i2400m_l3l4_hdr *l3l4_hdr = payload; + unsigned msg_type; + + result = i2400m_msg_size_check(i2400m, l3l4_hdr, size); + if (result < 0) { + dev_err(dev, "HW BUG? device sent a bad trace message: %d\n", + result); + goto error_check; + } + msg_type = le16_to_cpu(l3l4_hdr->type); + d_printf(1, dev, "Trace %s 0x%04x: %zu bytes\n", + msg_type & I2400M_MT_REPORT_MASK ? "REPORT" : "CMD/SET/GET", + msg_type, size); + d_dump(2, dev, l3l4_hdr, size); + if (unlikely(i2400m->ready == 0)) /* only send if up */ + return; + result = wimax_msg(wimax_dev, "trace", l3l4_hdr, size, GFP_KERNEL); + if (result < 0) + dev_err(dev, "error sending trace to userspace: %d\n", + result); +error_check: + return; +} + + +/* + * Act on a received payload + * + * @i2400m: device instance + * @skb_rx: skb where the transaction was received + * @single: 1 if there is only one payload, 0 otherwise + * @pld: payload descriptor + * @payload: payload data + * + * Upon reception of a payload, look at its guts in the payload + * descriptor and decide what to do with it. + */ +static +void i2400m_rx_payload(struct i2400m *i2400m, struct sk_buff *skb_rx, + unsigned single, const struct i2400m_pld *pld, + const void *payload) +{ + struct device *dev = i2400m_dev(i2400m); + size_t pl_size = i2400m_pld_size(pld); + enum i2400m_pt pl_type = i2400m_pld_type(pld); + + switch (pl_type) { + case I2400M_PT_DATA: + d_printf(3, dev, "RX: data payload %zu bytes\n", pl_size); + i2400m_net_rx(i2400m, skb_rx, single, payload, pl_size); + break; + case I2400M_PT_CTRL: + i2400m_rx_ctl(i2400m, skb_rx, payload, pl_size); + break; + case I2400M_PT_TRACE: + i2400m_rx_trace(i2400m, payload, pl_size); + break; + default: /* Anything else shouldn't come to the host */ + if (printk_ratelimit()) + dev_err(dev, "RX: HW BUG? unexpected payload type %u\n", + pl_type); + } +} + + +/* + * Check a received transaction's message header + * + * @i2400m: device descriptor + * @msg_hdr: message header + * @buf_size: size of the received buffer + * + * Check that the declarations done by a RX buffer message header are + * sane and consistent with the amount of data that was received. + */ +static +int i2400m_rx_msg_hdr_check(struct i2400m *i2400m, + const struct i2400m_msg_hdr *msg_hdr, + size_t buf_size) +{ + int result = -EIO; + struct device *dev = i2400m_dev(i2400m); + if (buf_size < sizeof(*msg_hdr)) { + dev_err(dev, "RX: HW BUG? message with short header (%zu " + "vs %zu bytes expected)\n", buf_size, sizeof(*msg_hdr)); + goto error; + } + if (msg_hdr->barker != cpu_to_le32(I2400M_D2H_MSG_BARKER)) { + dev_err(dev, "RX: HW BUG? message received with unknown " + "barker 0x%08x (buf_size %zu bytes)\n", + le32_to_cpu(msg_hdr->barker), buf_size); + goto error; + } + if (msg_hdr->num_pls == 0) { + dev_err(dev, "RX: HW BUG? zero payload packets in message\n"); + goto error; + } + if (le16_to_cpu(msg_hdr->num_pls) > I2400M_MAX_PLS_IN_MSG) { + dev_err(dev, "RX: HW BUG? message contains more payload " + "than maximum; ignoring.\n"); + goto error; + } + result = 0; +error: + return result; +} + + +/* + * Check a payload descriptor against the received data + * + * @i2400m: device descriptor + * @pld: payload descriptor + * @pl_itr: offset (in bytes) in the received buffer the payload is + * located + * @buf_size: size of the received buffer + * + * Given a payload descriptor (part of a RX buffer), check it is sane + * and that the data it declares fits in the buffer. + */ +static +int i2400m_rx_pl_descr_check(struct i2400m *i2400m, + const struct i2400m_pld *pld, + size_t pl_itr, size_t buf_size) +{ + int result = -EIO; + struct device *dev = i2400m_dev(i2400m); + size_t pl_size = i2400m_pld_size(pld); + enum i2400m_pt pl_type = i2400m_pld_type(pld); + + if (pl_size > i2400m->bus_pl_size_max) { + dev_err(dev, "RX: HW BUG? payload @%zu: size %zu is " + "bigger than maximum %zu; ignoring message\n", + pl_itr, pl_size, i2400m->bus_pl_size_max); + goto error; + } + if (pl_itr + pl_size > buf_size) { /* enough? */ + dev_err(dev, "RX: HW BUG? payload @%zu: size %zu " + "goes beyond the received buffer " + "size (%zu bytes); ignoring message\n", + pl_itr, pl_size, buf_size); + goto error; + } + if (pl_type >= I2400M_PT_ILLEGAL) { + dev_err(dev, "RX: HW BUG? illegal payload type %u; " + "ignoring message\n", pl_type); + goto error; + } + result = 0; +error: + return result; +} + + +/** + * i2400m_rx - Receive a buffer of data from the device + * + * @i2400m: device descriptor + * @skb: skbuff where the data has been received + * + * Parse in a buffer of data that contains an RX message sent from the + * device. See the file header for the format. Run all checks on the + * buffer header, then run over each payload's descriptors, verify + * their consistency and act on each payload's contents. If + * everything is succesful, update the device's statistics. + * + * Note: You need to set the skb to contain only the length of the + * received buffer; for that, use skb_trim(skb, RECEIVED_SIZE). + * + * Returns: + * + * 0 if ok, < 0 errno on error + * + * If ok, this function owns now the skb and the caller DOESN'T have + * to run kfree_skb() on it. However, on error, the caller still owns + * the skb and it is responsible for releasing it. + */ +int i2400m_rx(struct i2400m *i2400m, struct sk_buff *skb) +{ + int i, result; + struct device *dev = i2400m_dev(i2400m); + const struct i2400m_msg_hdr *msg_hdr; + size_t pl_itr, pl_size, skb_len; + unsigned long flags; + unsigned num_pls; + + skb_len = skb->len; + d_fnstart(4, dev, "(i2400m %p skb %p [size %zu])\n", + i2400m, skb, skb_len); + result = -EIO; + msg_hdr = (void *) skb->data; + result = i2400m_rx_msg_hdr_check(i2400m, msg_hdr, skb->len); + if (result < 0) + goto error_msg_hdr_check; + result = -EIO; + num_pls = le16_to_cpu(msg_hdr->num_pls); + pl_itr = sizeof(*msg_hdr) + /* Check payload descriptor(s) */ + num_pls * sizeof(msg_hdr->pld[0]); + pl_itr = ALIGN(pl_itr, I2400M_PL_PAD); + if (pl_itr > skb->len) { /* got all the payload descriptors? */ + dev_err(dev, "RX: HW BUG? message too short (%u bytes) for " + "%u payload descriptors (%zu each, total %zu)\n", + skb->len, num_pls, sizeof(msg_hdr->pld[0]), pl_itr); + goto error_pl_descr_short; + } + /* Walk each payload payload--check we really got it */ + for (i = 0; i < num_pls; i++) { + /* work around old gcc warnings */ + pl_size = i2400m_pld_size(&msg_hdr->pld[i]); + result = i2400m_rx_pl_descr_check(i2400m, &msg_hdr->pld[i], + pl_itr, skb->len); + if (result < 0) + goto error_pl_descr_check; + i2400m_rx_payload(i2400m, skb, num_pls == 1, &msg_hdr->pld[i], + skb->data + pl_itr); + pl_itr += ALIGN(pl_size, I2400M_PL_PAD); + cond_resched(); /* Don't monopolize */ + } + kfree_skb(skb); + /* Update device statistics */ + spin_lock_irqsave(&i2400m->rx_lock, flags); + i2400m->rx_pl_num += i; + if (i > i2400m->rx_pl_max) + i2400m->rx_pl_max = i; + if (i < i2400m->rx_pl_min) + i2400m->rx_pl_min = i; + i2400m->rx_num++; + i2400m->rx_size_acc += skb->len; + if (skb->len < i2400m->rx_size_min) + i2400m->rx_size_min = skb->len; + if (skb->len > i2400m->rx_size_max) + i2400m->rx_size_max = skb->len; + spin_unlock_irqrestore(&i2400m->rx_lock, flags); +error_pl_descr_check: +error_pl_descr_short: +error_msg_hdr_check: + d_fnend(4, dev, "(i2400m %p skb %p [size %zu]) = %d\n", + i2400m, skb, skb_len, result); + return result; +} +EXPORT_SYMBOL_GPL(i2400m_rx); diff --git a/drivers/net/wimax/i2400m/tx.c b/drivers/net/wimax/i2400m/tx.c new file mode 100644 index 00000000000..613a88ffd65 --- /dev/null +++ b/drivers/net/wimax/i2400m/tx.c @@ -0,0 +1,817 @@ +/* + * 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 + * imcomplete 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 "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. + */ + I2400M_TX_BUF_SIZE = 32768, + /** + * 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. + */ + I2400M_TX_PLD_MAX = 12, + I2400M_TX_PLD_SIZE = sizeof(struct i2400m_msg_hdr) + + I2400M_TX_PLD_MAX * sizeof(struct i2400m_pld), + I2400M_TX_SKIP = 0x80000000, +}; + +#define TAIL_FULL ((void *)~(unsigned long)NULL) + +/* + * 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. + * + * 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. + * + * 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) +{ + 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_BUF_SIZE - i2400m->tx_in % I2400M_TX_BUF_SIZE; + if (tail_room < needed_size) { + if (i2400m->tx_out % I2400M_TX_BUF_SIZE + < i2400m->tx_in % I2400M_TX_BUF_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). + * + * Note: + * + * Assumes i2400m->tx_lock is taken, and we use that as a barrier + */ +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_BUF_SIZE - tx_in; + struct i2400m_msg_hdr *msg = i2400m->tx_buf + tx_in; + 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; + BUG_ON(i2400m->tx_msg != NULL); +try_head: + tx_msg = i2400m_tx_fifo_push(i2400m, I2400M_TX_PLD_SIZE, 0); + 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"); + 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 |