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horizon.c
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horizon.c
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/*
Madge Horizon ATM Adapter driver.
Copyright (C) 1995-1999 Madge Networks Ltd.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
The GNU GPL is contained in /usr/doc/copyright/GPL on a Debian
system and in the file COPYING in the Linux kernel source.
*/
/*
IMPORTANT NOTE: Madge Networks no longer makes the adapters
supported by this driver and makes no commitment to maintain it.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/pci.h>
#include <linux/errno.h>
#include <linux/atm.h>
#include <linux/atmdev.h>
#include <linux/sonet.h>
#include <linux/skbuff.h>
#include <linux/time.h>
#include <linux/delay.h>
#include <linux/uio.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/wait.h>
#include <linux/slab.h>
#include <asm/io.h>
#include <linux/atomic.h>
#include <asm/uaccess.h>
#include <asm/string.h>
#include <asm/byteorder.h>
#include "horizon.h"
#define maintainer_string "Giuliano Procida at Madge Networks <gprocida@madge.com>"
#define description_string "Madge ATM Horizon [Ultra] driver"
#define version_string "1.2.1"
static inline void __init show_version (void) {
printk ("%s version %s\n", description_string, version_string);
}
/*
CREDITS
Driver and documentation by:
Chris Aston Madge Networks
Giuliano Procida Madge Networks
Simon Benham Madge Networks
Simon Johnson Madge Networks
Various Others Madge Networks
Some inspiration taken from other drivers by:
Alexandru Cucos UTBv
Kari Mettinen University of Helsinki
Werner Almesberger EPFL LRC
Theory of Operation
I Hardware, detection, initialisation and shutdown.
1. Supported Hardware
This driver should handle all variants of the PCI Madge ATM adapters
with the Horizon chipset. These are all PCI cards supporting PIO, BM
DMA and a form of MMIO (registers only, not internal RAM).
The driver is only known to work with SONET and UTP Horizon Ultra
cards at 155Mb/s. However, code is in place to deal with both the
original Horizon and 25Mb/s operation.
There are two revisions of the Horizon ASIC: the original and the
Ultra. Details of hardware bugs are in section III.
The ASIC version can be distinguished by chip markings but is NOT
indicated by the PCI revision (all adapters seem to have PCI rev 1).
I believe that:
Horizon => Collage 25 PCI Adapter (UTP and STP)
Horizon Ultra => Collage 155 PCI Client (UTP or SONET)
Ambassador x => Collage 155 PCI Server (completely different)
Horizon (25Mb/s) is fitted with UTP and STP connectors. It seems to
have a Madge B154 plus glue logic serializer. I have also found a
really ancient version of this with slightly different glue. It
comes with the revision 0 (140-025-01) ASIC.
Horizon Ultra (155Mb/s) is fitted with either a Pulse Medialink
output (UTP) or an HP HFBR 5205 output (SONET). It has either
Madge's SAMBA framer or a SUNI-lite device (early versions). It
comes with the revision 1 (140-027-01) ASIC.
2. Detection
All Horizon-based cards present with the same PCI Vendor and Device
IDs. The standard Linux 2.2 PCI API is used to locate any cards and
to enable bus-mastering (with appropriate latency).
ATM_LAYER_STATUS in the control register distinguishes between the
two possible physical layers (25 and 155). It is not clear whether
the 155 cards can also operate at 25Mbps. We rely on the fact that a
card operates at 155 if and only if it has the newer Horizon Ultra
ASIC.
For 155 cards the two possible framers are probed for and then set
up for loop-timing.
3. Initialisation
The card is reset and then put into a known state. The physical
layer is configured for normal operation at the appropriate speed;
in the case of the 155 cards, the framer is initialised with
line-based timing; the internal RAM is zeroed and the allocation of
buffers for RX and TX is made; the Burnt In Address is read and
copied to the ATM ESI; various policy settings for RX (VPI bits,
unknown VCs, oam cells) are made. Ideally all policy items should be
configurable at module load (if not actually on-demand), however,
only the vpi vs vci bit allocation can be specified at insmod.
4. Shutdown
This is in response to module_cleaup. No VCs are in use and the card
should be idle; it is reset.
II Driver software (as it should be)
0. Traffic Parameters
The traffic classes (not an enumeration) are currently: ATM_NONE (no
traffic), ATM_UBR, ATM_CBR, ATM_VBR and ATM_ABR, ATM_ANYCLASS
(compatible with everything). Together with (perhaps only some of)
the following items they make up the traffic specification.
struct atm_trafprm {
unsigned char traffic_class; traffic class (ATM_UBR, ...)
int max_pcr; maximum PCR in cells per second
int pcr; desired PCR in cells per second
int min_pcr; minimum PCR in cells per second
int max_cdv; maximum CDV in microseconds
int max_sdu; maximum SDU in bytes
};
Note that these denote bandwidth available not bandwidth used; the
possibilities according to ATMF are:
Real Time (cdv and max CDT given)
CBR(pcr) pcr bandwidth always available
rtVBR(pcr,scr,mbs) scr bandwidth always available, up to pcr at mbs too
Non Real Time
nrtVBR(pcr,scr,mbs) scr bandwidth always available, up to pcr at mbs too
UBR()
ABR(mcr,pcr) mcr bandwidth always available, up to pcr (depending) too
mbs is max burst size (bucket)
pcr and scr have associated cdvt values
mcr is like scr but has no cdtv
cdtv may differ at each hop
Some of the above items are qos items (as opposed to traffic
parameters). We have nothing to do with qos. All except ABR can have
their traffic parameters converted to GCRA parameters. The GCRA may
be implemented as a (real-number) leaky bucket. The GCRA can be used
in complicated ways by switches and in simpler ways by end-stations.
It can be used both to filter incoming cells and shape out-going
cells.
ATM Linux actually supports:
ATM_NONE() (no traffic in this direction)
ATM_UBR(max_frame_size)
ATM_CBR(max/min_pcr, max_cdv, max_frame_size)
0 or ATM_MAX_PCR are used to indicate maximum available PCR
A traffic specification consists of the AAL type and separate
traffic specifications for either direction. In ATM Linux it is:
struct atm_qos {
struct atm_trafprm txtp;
struct atm_trafprm rxtp;
unsigned char aal;
};
AAL types are:
ATM_NO_AAL AAL not specified
ATM_AAL0 "raw" ATM cells
ATM_AAL1 AAL1 (CBR)
ATM_AAL2 AAL2 (VBR)
ATM_AAL34 AAL3/4 (data)
ATM_AAL5 AAL5 (data)
ATM_SAAL signaling AAL
The Horizon has support for AAL frame types: 0, 3/4 and 5. However,
it does not implement AAL 3/4 SAR and it has a different notion of
"raw cell" to ATM Linux's (48 bytes vs. 52 bytes) so neither are
supported by this driver.
The Horizon has limited support for ABR (including UBR), VBR and
CBR. Each TX channel has a bucket (containing up to 31 cell units)
and two timers (PCR and SCR) associated with it that can be used to
govern cell emissions and host notification (in the case of ABR this
is presumably so that RM cells may be emitted at appropriate times).
The timers may either be disabled or may be set to any of 240 values
(determined by the clock crystal, a fixed (?) per-device divider, a
configurable divider and a configurable timer preload value).
At the moment only UBR and CBR are supported by the driver. VBR will
be supported as soon as ATM for Linux supports it. ABR support is
very unlikely as RM cell handling is completely up to the driver.
1. TX (TX channel setup and TX transfer)
The TX half of the driver owns the TX Horizon registers. The TX
component in the IRQ handler is the BM completion handler. This can
only be entered when tx_busy is true (enforced by hardware). The
other TX component can only be entered when tx_busy is false
(enforced by driver). So TX is single-threaded.
Apart from a minor optimisation to not re-select the last channel,
the TX send component works as follows:
Atomic test and set tx_busy until we succeed; we should implement
some sort of timeout so that tx_busy will never be stuck at true.
If no TX channel is set up for this VC we wait for an idle one (if
necessary) and set it up.
At this point we have a TX channel ready for use. We wait for enough
buffers to become available then start a TX transmit (set the TX
descriptor, schedule transfer, exit).
The IRQ component handles TX completion (stats, free buffer, tx_busy
unset, exit). We also re-schedule further transfers for the same
frame if needed.
TX setup in more detail:
TX open is a nop, the relevant information is held in the hrz_vcc
(vcc->dev_data) structure and is "cached" on the card.
TX close gets the TX lock and clears the channel from the "cache".
2. RX (Data Available and RX transfer)
The RX half of the driver owns the RX registers. There are two RX
components in the IRQ handler: the data available handler deals with
fresh data that has arrived on the card, the BM completion handler
is very similar to the TX completion handler. The data available
handler grabs the rx_lock and it is only released once the data has
been discarded or completely transferred to the host. The BM
completion handler only runs when the lock is held; the data
available handler is locked out over the same period.
Data available on the card triggers an interrupt. If the data is not
suitable for our existing RX channels or we cannot allocate a buffer
it is flushed. Otherwise an RX receive is scheduled. Multiple RX
transfers may be scheduled for the same frame.
RX setup in more detail:
RX open...
RX close...
III Hardware Bugs
0. Byte vs Word addressing of adapter RAM.
A design feature; see the .h file (especially the memory map).
1. Bus Master Data Transfers (original Horizon only, fixed in Ultra)
The host must not start a transmit direction transfer at a
non-four-byte boundary in host memory. Instead the host should
perform a byte, or a two byte, or one byte followed by two byte
transfer in order to start the rest of the transfer on a four byte
boundary. RX is OK.
Simultaneous transmit and receive direction bus master transfers are
not allowed.
The simplest solution to these two is to always do PIO (never DMA)
in the TX direction on the original Horizon. More complicated
solutions are likely to hurt my brain.
2. Loss of buffer on close VC
When a VC is being closed, the buffer associated with it is not
returned to the pool. The host must store the reference to this
buffer and when opening a new VC then give it to that new VC.
The host intervention currently consists of stacking such a buffer
pointer at VC close and checking the stack at VC open.
3. Failure to close a VC
If a VC is currently receiving a frame then closing the VC may fail
and the frame continues to be received.
The solution is to make sure any received frames are flushed when
ready. This is currently done just before the solution to 2.
4. PCI bus (original Horizon only, fixed in Ultra)
Reading from the data port prior to initialisation will hang the PCI
bus. Just don't do that then! We don't.
IV To Do List
. Timer code may be broken.
. Allow users to specify buffer allocation split for TX and RX.
. Deal once and for all with buggy VC close.
. Handle interrupted and/or non-blocking operations.
. Change some macros to functions and move from .h to .c.
. Try to limit the number of TX frames each VC may have queued, in
order to reduce the chances of TX buffer exhaustion.
. Implement VBR (bucket and timers not understood) and ABR (need to
do RM cells manually); also no Linux support for either.
. Implement QoS changes on open VCs (involves extracting parts of VC open
and close into separate functions and using them to make changes).
*/
/********** globals **********/
static void do_housekeeping (unsigned long arg);
static unsigned short debug = 0;
static unsigned short vpi_bits = 0;
static int max_tx_size = 9000;
static int max_rx_size = 9000;
static unsigned char pci_lat = 0;
/********** access functions **********/
/* Read / Write Horizon registers */
static inline void wr_regl (const hrz_dev * dev, unsigned char reg, u32 data) {
outl (cpu_to_le32 (data), dev->iobase + reg);
}
static inline u32 rd_regl (const hrz_dev * dev, unsigned char reg) {
return le32_to_cpu (inl (dev->iobase + reg));
}
static inline void wr_regw (const hrz_dev * dev, unsigned char reg, u16 data) {
outw (cpu_to_le16 (data), dev->iobase + reg);
}
static inline u16 rd_regw (const hrz_dev * dev, unsigned char reg) {
return le16_to_cpu (inw (dev->iobase + reg));
}
static inline void wrs_regb (const hrz_dev * dev, unsigned char reg, void * addr, u32 len) {
outsb (dev->iobase + reg, addr, len);
}
static inline void rds_regb (const hrz_dev * dev, unsigned char reg, void * addr, u32 len) {
insb (dev->iobase + reg, addr, len);
}
/* Read / Write to a given address in Horizon buffer memory.
Interrupts must be disabled between the address register and data
port accesses as these must form an atomic operation. */
static inline void wr_mem (const hrz_dev * dev, HDW * addr, u32 data) {
// wr_regl (dev, MEM_WR_ADDR_REG_OFF, (u32) addr);
wr_regl (dev, MEM_WR_ADDR_REG_OFF, (addr - (HDW *) 0) * sizeof(HDW));
wr_regl (dev, MEMORY_PORT_OFF, data);
}
static inline u32 rd_mem (const hrz_dev * dev, HDW * addr) {
// wr_regl (dev, MEM_RD_ADDR_REG_OFF, (u32) addr);
wr_regl (dev, MEM_RD_ADDR_REG_OFF, (addr - (HDW *) 0) * sizeof(HDW));
return rd_regl (dev, MEMORY_PORT_OFF);
}
static inline void wr_framer (const hrz_dev * dev, u32 addr, u32 data) {
wr_regl (dev, MEM_WR_ADDR_REG_OFF, (u32) addr | 0x80000000);
wr_regl (dev, MEMORY_PORT_OFF, data);
}
static inline u32 rd_framer (const hrz_dev * dev, u32 addr) {
wr_regl (dev, MEM_RD_ADDR_REG_OFF, (u32) addr | 0x80000000);
return rd_regl (dev, MEMORY_PORT_OFF);
}
/********** specialised access functions **********/
/* RX */
static inline void FLUSH_RX_CHANNEL (hrz_dev * dev, u16 channel) {
wr_regw (dev, RX_CHANNEL_PORT_OFF, FLUSH_CHANNEL | channel);
return;
}
static void WAIT_FLUSH_RX_COMPLETE (hrz_dev * dev) {
while (rd_regw (dev, RX_CHANNEL_PORT_OFF) & FLUSH_CHANNEL)
;
return;
}
static inline void SELECT_RX_CHANNEL (hrz_dev * dev, u16 channel) {
wr_regw (dev, RX_CHANNEL_PORT_OFF, channel);
return;
}
static void WAIT_UPDATE_COMPLETE (hrz_dev * dev) {
while (rd_regw (dev, RX_CHANNEL_PORT_OFF) & RX_CHANNEL_UPDATE_IN_PROGRESS)
;
return;
}
/* TX */
static inline void SELECT_TX_CHANNEL (hrz_dev * dev, u16 tx_channel) {
wr_regl (dev, TX_CHANNEL_PORT_OFF, tx_channel);
return;
}
/* Update or query one configuration parameter of a particular channel. */
static inline void update_tx_channel_config (hrz_dev * dev, short chan, u8 mode, u16 value) {
wr_regw (dev, TX_CHANNEL_CONFIG_COMMAND_OFF,
chan * TX_CHANNEL_CONFIG_MULT | mode);
wr_regw (dev, TX_CHANNEL_CONFIG_DATA_OFF, value);
return;
}
static inline u16 query_tx_channel_config (hrz_dev * dev, short chan, u8 mode) {
wr_regw (dev, TX_CHANNEL_CONFIG_COMMAND_OFF,
chan * TX_CHANNEL_CONFIG_MULT | mode);
return rd_regw (dev, TX_CHANNEL_CONFIG_DATA_OFF);
}
/********** dump functions **********/
static inline void dump_skb (char * prefix, unsigned int vc, struct sk_buff * skb) {
#ifdef DEBUG_HORIZON
unsigned int i;
unsigned char * data = skb->data;
PRINTDB (DBG_DATA, "%s(%u) ", prefix, vc);
for (i=0; i<skb->len && i < 256;i++)
PRINTDM (DBG_DATA, "%02x ", data[i]);
PRINTDE (DBG_DATA,"");
#else
(void) prefix;
(void) vc;
(void) skb;
#endif
return;
}
static inline void dump_regs (hrz_dev * dev) {
#ifdef DEBUG_HORIZON
PRINTD (DBG_REGS, "CONTROL 0: %#x", rd_regl (dev, CONTROL_0_REG));
PRINTD (DBG_REGS, "RX CONFIG: %#x", rd_regw (dev, RX_CONFIG_OFF));
PRINTD (DBG_REGS, "TX CONFIG: %#x", rd_regw (dev, TX_CONFIG_OFF));
PRINTD (DBG_REGS, "TX STATUS: %#x", rd_regw (dev, TX_STATUS_OFF));
PRINTD (DBG_REGS, "IRQ ENBLE: %#x", rd_regl (dev, INT_ENABLE_REG_OFF));
PRINTD (DBG_REGS, "IRQ SORCE: %#x", rd_regl (dev, INT_SOURCE_REG_OFF));
#else
(void) dev;
#endif
return;
}
static inline void dump_framer (hrz_dev * dev) {
#ifdef DEBUG_HORIZON
unsigned int i;
PRINTDB (DBG_REGS, "framer registers:");
for (i = 0; i < 0x10; ++i)
PRINTDM (DBG_REGS, " %02x", rd_framer (dev, i));
PRINTDE (DBG_REGS,"");
#else
(void) dev;
#endif
return;
}
/********** VPI/VCI <-> (RX) channel conversions **********/
/* RX channels are 10 bit integers, these fns are quite paranoid */
static inline int channel_to_vpivci (const u16 channel, short * vpi, int * vci) {
unsigned short vci_bits = 10 - vpi_bits;
if ((channel & RX_CHANNEL_MASK) == channel) {
*vci = channel & ((~0)<<vci_bits);
*vpi = channel >> vci_bits;
return channel ? 0 : -EINVAL;
}
return -EINVAL;
}
static inline int vpivci_to_channel (u16 * channel, const short vpi, const int vci) {
unsigned short vci_bits = 10 - vpi_bits;
if (0 <= vpi && vpi < 1<<vpi_bits && 0 <= vci && vci < 1<<vci_bits) {
*channel = vpi<<vci_bits | vci;
return *channel ? 0 : -EINVAL;
}
return -EINVAL;
}
/********** decode RX queue entries **********/
static inline u16 rx_q_entry_to_length (u32 x) {
return x & RX_Q_ENTRY_LENGTH_MASK;
}
static inline u16 rx_q_entry_to_rx_channel (u32 x) {
return (x>>RX_Q_ENTRY_CHANNEL_SHIFT) & RX_CHANNEL_MASK;
}
/* Cell Transmit Rate Values
*
* the cell transmit rate (cells per sec) can be set to a variety of
* different values by specifying two parameters: a timer preload from
* 1 to 16 (stored as 0 to 15) and a clock divider (2 to the power of
* an exponent from 0 to 14; the special value 15 disables the timer).
*
* cellrate = baserate / (preload * 2^divider)
*
* The maximum cell rate that can be specified is therefore just the
* base rate. Halving the preload is equivalent to adding 1 to the
* divider and so values 1 to 8 of the preload are redundant except
* in the case of a maximal divider (14).
*
* Given a desired cell rate, an algorithm to determine the preload
* and divider is:
*
* a) x = baserate / cellrate, want p * 2^d = x (as far as possible)
* b) if x > 16 * 2^14 then set p = 16, d = 14 (min rate), done
* if x <= 16 then set p = x, d = 0 (high rates), done
* c) now have 16 < x <= 2^18, or 1 < x/16 <= 2^14 and we want to
* know n such that 2^(n-1) < x/16 <= 2^n, so slide a bit until
* we find the range (n will be between 1 and 14), set d = n
* d) Also have 8 < x/2^n <= 16, so set p nearest x/2^n
*
* The algorithm used below is a minor variant of the above.
*
* The base rate is derived from the oscillator frequency (Hz) using a
* fixed divider:
*
* baserate = freq / 32 in the case of some Unknown Card
* baserate = freq / 8 in the case of the Horizon 25
* baserate = freq / 8 in the case of the Horizon Ultra 155
*
* The Horizon cards have oscillators and base rates as follows:
*
* Card Oscillator Base Rate
* Unknown Card 33 MHz 1.03125 MHz (33 MHz = PCI freq)
* Horizon 25 32 MHz 4 MHz
* Horizon Ultra 155 40 MHz 5 MHz
*
* The following defines give the base rates in Hz. These were
* previously a factor of 100 larger, no doubt someone was using
* cps*100.
*/
#define BR_UKN 1031250l
#define BR_HRZ 4000000l
#define BR_ULT 5000000l
// d is an exponent
#define CR_MIND 0
#define CR_MAXD 14
// p ranges from 1 to a power of 2
#define CR_MAXPEXP 4
static int make_rate (const hrz_dev * dev, u32 c, rounding r,
u16 * bits, unsigned int * actual)
{
// note: rounding the rate down means rounding 'p' up
const unsigned long br = test_bit(ultra, &dev->flags) ? BR_ULT : BR_HRZ;
u32 div = CR_MIND;
u32 pre;
// br_exp and br_man are used to avoid overflowing (c*maxp*2^d) in
// the tests below. We could think harder about exact possibilities
// of failure...
unsigned long br_man = br;
unsigned int br_exp = 0;
PRINTD (DBG_QOS|DBG_FLOW, "make_rate b=%lu, c=%u, %s", br, c,
r == round_up ? "up" : r == round_down ? "down" : "nearest");
// avoid div by zero
if (!c) {
PRINTD (DBG_QOS|DBG_ERR, "zero rate is not allowed!");
return -EINVAL;
}
while (br_exp < CR_MAXPEXP + CR_MIND && (br_man % 2 == 0)) {
br_man = br_man >> 1;
++br_exp;
}
// (br >>br_exp) <<br_exp == br and
// br_exp <= CR_MAXPEXP+CR_MIND
if (br_man <= (c << (CR_MAXPEXP+CR_MIND-br_exp))) {
// Equivalent to: B <= (c << (MAXPEXP+MIND))
// take care of rounding
switch (r) {
case round_down:
pre = DIV_ROUND_UP(br, c<<div);
// but p must be non-zero
if (!pre)
pre = 1;
break;
case round_nearest:
pre = DIV_ROUND_CLOSEST(br, c<<div);
// but p must be non-zero
if (!pre)
pre = 1;
break;
default: /* round_up */
pre = br/(c<<div);
// but p must be non-zero
if (!pre)
return -EINVAL;
}
PRINTD (DBG_QOS, "A: p=%u, d=%u", pre, div);
goto got_it;
}
// at this point we have
// d == MIND and (c << (MAXPEXP+MIND)) < B
while (div < CR_MAXD) {
div++;
if (br_man <= (c << (CR_MAXPEXP+div-br_exp))) {
// Equivalent to: B <= (c << (MAXPEXP+d))
// c << (MAXPEXP+d-1) < B <= c << (MAXPEXP+d)
// 1 << (MAXPEXP-1) < B/2^d/c <= 1 << MAXPEXP
// MAXP/2 < B/c2^d <= MAXP
// take care of rounding
switch (r) {
case round_down:
pre = DIV_ROUND_UP(br, c<<div);
break;
case round_nearest:
pre = DIV_ROUND_CLOSEST(br, c<<div);
break;
default: /* round_up */
pre = br/(c<<div);
}
PRINTD (DBG_QOS, "B: p=%u, d=%u", pre, div);
goto got_it;
}
}
// at this point we have
// d == MAXD and (c << (MAXPEXP+MAXD)) < B
// but we cannot go any higher
// take care of rounding
if (r == round_down)
return -EINVAL;
pre = 1 << CR_MAXPEXP;
PRINTD (DBG_QOS, "C: p=%u, d=%u", pre, div);
got_it:
// paranoia
if (div > CR_MAXD || (!pre) || pre > 1<<CR_MAXPEXP) {
PRINTD (DBG_QOS, "set_cr internal failure: d=%u p=%u",
div, pre);
return -EINVAL;
} else {
if (bits)
*bits = (div<<CLOCK_SELECT_SHIFT) | (pre-1);
if (actual) {
*actual = DIV_ROUND_UP(br, pre<<div);
PRINTD (DBG_QOS, "actual rate: %u", *actual);
}
return 0;
}
}
static int make_rate_with_tolerance (const hrz_dev * dev, u32 c, rounding r, unsigned int tol,
u16 * bit_pattern, unsigned int * actual) {
unsigned int my_actual;
PRINTD (DBG_QOS|DBG_FLOW, "make_rate_with_tolerance c=%u, %s, tol=%u",
c, (r == round_up) ? "up" : (r == round_down) ? "down" : "nearest", tol);
if (!actual)
// actual rate is not returned
actual = &my_actual;
if (make_rate (dev, c, round_nearest, bit_pattern, actual))
// should never happen as round_nearest always succeeds
return -1;
if (c - tol <= *actual && *actual <= c + tol)
// within tolerance
return 0;
else
// intolerant, try rounding instead
return make_rate (dev, c, r, bit_pattern, actual);
}
/********** Listen on a VC **********/
static int hrz_open_rx (hrz_dev * dev, u16 channel) {
// is there any guarantee that we don't get two simulataneous
// identical calls of this function from different processes? yes
// rate_lock
unsigned long flags;
u32 channel_type; // u16?
u16 buf_ptr = RX_CHANNEL_IDLE;
rx_ch_desc * rx_desc = &memmap->rx_descs[channel];
PRINTD (DBG_FLOW, "hrz_open_rx %x", channel);
spin_lock_irqsave (&dev->mem_lock, flags);
channel_type = rd_mem (dev, &rx_desc->wr_buf_type) & BUFFER_PTR_MASK;
spin_unlock_irqrestore (&dev->mem_lock, flags);
// very serious error, should never occur
if (channel_type != RX_CHANNEL_DISABLED) {
PRINTD (DBG_ERR|DBG_VCC, "RX channel for VC already open");
return -EBUSY; // clean up?
}
// Give back spare buffer
if (dev->noof_spare_buffers) {
buf_ptr = dev->spare_buffers[--dev->noof_spare_buffers];
PRINTD (DBG_VCC, "using a spare buffer: %u", buf_ptr);
// should never occur
if (buf_ptr == RX_CHANNEL_DISABLED || buf_ptr == RX_CHANNEL_IDLE) {
// but easy to recover from
PRINTD (DBG_ERR|DBG_VCC, "bad spare buffer pointer, using IDLE");
buf_ptr = RX_CHANNEL_IDLE;
}
} else {
PRINTD (DBG_VCC, "using IDLE buffer pointer");
}
// Channel is currently disabled so change its status to idle
// do we really need to save the flags again?
spin_lock_irqsave (&dev->mem_lock, flags);
wr_mem (dev, &rx_desc->wr_buf_type,
buf_ptr | CHANNEL_TYPE_AAL5 | FIRST_CELL_OF_AAL5_FRAME);
if (buf_ptr != RX_CHANNEL_IDLE)
wr_mem (dev, &rx_desc->rd_buf_type, buf_ptr);
spin_unlock_irqrestore (&dev->mem_lock, flags);
// rxer->rate = make_rate (qos->peak_cells);
PRINTD (DBG_FLOW, "hrz_open_rx ok");
return 0;
}
#if 0
/********** change vc rate for a given vc **********/
static void hrz_change_vc_qos (ATM_RXER * rxer, MAAL_QOS * qos) {
rxer->rate = make_rate (qos->peak_cells);
}
#endif
/********** free an skb (as per ATM device driver documentation) **********/
static void hrz_kfree_skb (struct sk_buff * skb) {
if (ATM_SKB(skb)->vcc->pop) {
ATM_SKB(skb)->vcc->pop (ATM_SKB(skb)->vcc, skb);
} else {
dev_kfree_skb_any (skb);
}
}
/********** cancel listen on a VC **********/
static void hrz_close_rx (hrz_dev * dev, u16 vc) {
unsigned long flags;
u32 value;
u32 r1, r2;
rx_ch_desc * rx_desc = &memmap->rx_descs[vc];
int was_idle = 0;
spin_lock_irqsave (&dev->mem_lock, flags);
value = rd_mem (dev, &rx_desc->wr_buf_type) & BUFFER_PTR_MASK;
spin_unlock_irqrestore (&dev->mem_lock, flags);
if (value == RX_CHANNEL_DISABLED) {
// I suppose this could happen once we deal with _NONE traffic properly
PRINTD (DBG_VCC, "closing VC: RX channel %u already disabled", vc);
return;
}
if (value == RX_CHANNEL_IDLE)
was_idle = 1;
spin_lock_irqsave (&dev->mem_lock, flags);
for (;;) {
wr_mem (dev, &rx_desc->wr_buf_type, RX_CHANNEL_DISABLED);
if ((rd_mem (dev, &rx_desc->wr_buf_type) & BUFFER_PTR_MASK) == RX_CHANNEL_DISABLED)
break;
was_idle = 0;
}
if (was_idle) {
spin_unlock_irqrestore (&dev->mem_lock, flags);
return;
}
WAIT_FLUSH_RX_COMPLETE(dev);
// XXX Is this all really necessary? We can rely on the rx_data_av
// handler to discard frames that remain queued for delivery. If the
// worry is that immediately reopening the channel (perhaps by a
// different process) may cause some data to be mis-delivered then
// there may still be a simpler solution (such as busy-waiting on
// rx_busy once the channel is disabled or before a new one is
// opened - does this leave any holes?). Arguably setting up and
// tearing down the TX and RX halves of each virtual circuit could
// most safely be done within ?x_busy protected regions.
// OK, current changes are that Simon's marker is disabled and we DO
// look for NULL rxer elsewhere. The code here seems flush frames
// and then remember the last dead cell belonging to the channel
// just disabled - the cell gets relinked at the next vc_open.
// However, when all VCs are closed or only a few opened there are a
// handful of buffers that are unusable.
// Does anyone feel like documenting spare_buffers properly?
// Does anyone feel like fixing this in a nicer way?
// Flush any data which is left in the channel
for (;;) {
// Change the rx channel port to something different to the RX
// channel we are trying to close to force Horizon to flush the rx
// channel read and write pointers.
u16 other = vc^(RX_CHANS/2);
SELECT_RX_CHANNEL (dev, other);
WAIT_UPDATE_COMPLETE (dev);
r1 = rd_mem (dev, &rx_desc->rd_buf_type);
// Select this RX channel. Flush doesn't seem to work unless we
// select an RX channel before hand
SELECT_RX_CHANNEL (dev, vc);
WAIT_UPDATE_COMPLETE (dev);
// Attempt to flush a frame on this RX channel
FLUSH_RX_CHANNEL (dev, vc);
WAIT_FLUSH_RX_COMPLETE (dev);
// Force Horizon to flush rx channel read and write pointers as before
SELECT_RX_CHANNEL (dev, other);
WAIT_UPDATE_COMPLETE (dev);
r2 = rd_mem (dev, &rx_desc->rd_buf_type);
PRINTD (DBG_VCC|DBG_RX, "r1 = %u, r2 = %u", r1, r2);
if (r1 == r2) {
dev->spare_buffers[dev->noof_spare_buffers++] = (u16)r1;
break;
}
}
#if 0
{
rx_q_entry * wr_ptr = &memmap->rx_q_entries[rd_regw (dev, RX_QUEUE_WR_PTR_OFF)];
rx_q_entry * rd_ptr = dev->rx_q_entry;
PRINTD (DBG_VCC|DBG_RX, "rd_ptr = %u, wr_ptr = %u", rd_ptr, wr_ptr);
while (rd_ptr != wr_ptr) {
u32 x = rd_mem (dev, (HDW *) rd_ptr);
if (vc == rx_q_entry_to_rx_channel (x)) {
x |= SIMONS_DODGEY_MARKER;
PRINTD (DBG_RX|DBG_VCC|DBG_WARN, "marking a frame as dodgey");
wr_mem (dev, (HDW *) rd_ptr, x);
}
if (rd_ptr == dev->rx_q_wrap)
rd_ptr = dev->rx_q_reset;
else
rd_ptr++;
}
}
#endif
spin_unlock_irqrestore (&dev->mem_lock, flags);
return;
}
/********** schedule RX transfers **********/
// Note on tail recursion: a GCC developer said that it is not likely
// to be fixed soon, so do not define TAILRECUSRIONWORKS unless you
// are sure it does as you may otherwise overflow the kernel stack.
// giving this fn a return value would help GCC, allegedly
static void rx_schedule (hrz_dev * dev, int irq) {
unsigned int rx_bytes;
int pio_instead = 0;
#ifndef TAILRECURSIONWORKS
pio_instead = 1;
while (pio_instead) {
#endif
// bytes waiting for RX transfer
rx_bytes = dev->rx_bytes;
#if 0
spin_count = 0;
while (rd_regl (dev, MASTER_RX_COUNT_REG_OFF)) {
PRINTD (DBG_RX|DBG_WARN, "RX error: other PCI Bus Master RX still in progress!");
if (++spin_count > 10) {
PRINTD (DBG_RX|DBG_ERR, "spun out waiting PCI Bus Master RX completion");
wr_regl (dev, MASTER_RX_COUNT_REG_OFF, 0);
clear_bit (rx_busy, &dev->flags);
hrz_kfree_skb (dev->rx_skb);
return;
}
}
#endif
// this code follows the TX code but (at the moment) there is only
// one region - the skb itself. I don't know if this will change,
// but it doesn't hurt to have the code here, disabled.
if (rx_bytes) {
// start next transfer within same region
if (rx_bytes <= MAX_PIO_COUNT) {
PRINTD (DBG_RX|DBG_BUS, "(pio)");
pio_instead = 1;
}
if (rx_bytes <= MAX_TRANSFER_COUNT) {
PRINTD (DBG_RX|DBG_BUS, "(simple or last multi)");
dev->rx_bytes = 0;
} else {
PRINTD (DBG_RX|DBG_BUS, "(continuing multi)");
dev->rx_bytes = rx_bytes - MAX_TRANSFER_COUNT;
rx_bytes = MAX_TRANSFER_COUNT;
}
} else {
// rx_bytes == 0 -- we're between regions
// regions remaining to transfer
#if 0
unsigned int rx_regions = dev->rx_regions;
#else
unsigned int rx_regions = 0;
#endif