Commit 4481d609 authored by Daniel Drake's avatar Daniel Drake Committed by Jeff Garzik

[PATCH] zd1211rw: Add UW2453 RF support

This patch adds support for another radio appearing in new devices: the
Ubec UW2453. It's more complicated than the other RF's we support, but
Ubec publish full tech specs so we're able to understand the vendor code
relatively well.

Now that we support UW2453, we also support Atheros' new USB chip: the
AR5007UG. From the little info we have, this appears to be just a
rebranded ZD1211B.

This RF code doesn't work very well -- lots more TX/RX errors than the
other RFs. However, the vendor driver doesn't do any better, so this is
all we can do for now.

[kune@deine-taler.de: bug fixes]
Signed-off-by: default avatarDaniel Drake <dsd@gentoo.org>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 9c8fc71d
......@@ -3,7 +3,7 @@ obj-$(CONFIG_ZD1211RW) += zd1211rw.o
zd1211rw-objs := zd_chip.o zd_ieee80211.o \
zd_mac.o zd_netdev.o \
zd_rf_al2230.o zd_rf_rf2959.o \
zd_rf_al7230b.o \
zd_rf_al7230b.o zd_rf_uw2453.o \
zd_rf.o zd_usb.o zd_util.o
ifeq ($(CONFIG_ZD1211RW_DEBUG),y)
......
......@@ -608,6 +608,9 @@ enum {
#define CR_ZD1211B_TXOP CTL_REG(0x0b20)
#define CR_ZD1211B_RETRY_MAX CTL_REG(0x0b28)
/* Used to detect PLL lock */
#define UW2453_INTR_REG ((zd_addr_t)0x85c1)
#define CWIN_SIZE 0x007f043f
......
......@@ -67,25 +67,23 @@ void zd_rf_clear(struct zd_rf *rf)
int zd_rf_init_hw(struct zd_rf *rf, u8 type)
{
int r, t;
int r = 0;
int t;
struct zd_chip *chip = zd_rf_to_chip(rf);
ZD_ASSERT(mutex_is_locked(&chip->mutex));
switch (type) {
case RF2959_RF:
r = zd_rf_init_rf2959(rf);
if (r)
return r;
break;
case AL2230_RF:
r = zd_rf_init_al2230(rf);
if (r)
return r;
break;
case AL7230B_RF:
r = zd_rf_init_al7230b(rf);
if (r)
return r;
break;
case UW2453_RF:
r = zd_rf_init_uw2453(rf);
break;
default:
dev_err(zd_chip_dev(chip),
......@@ -94,6 +92,9 @@ int zd_rf_init_hw(struct zd_rf *rf, u8 type)
return -ENODEV;
}
if (r)
return r;
rf->type = type;
r = zd_chip_lock_phy_regs(chip);
......
......@@ -89,5 +89,6 @@ static inline int zd_rf_should_update_pwr_int(struct zd_rf *rf)
int zd_rf_init_rf2959(struct zd_rf *rf);
int zd_rf_init_al2230(struct zd_rf *rf);
int zd_rf_init_al7230b(struct zd_rf *rf);
int zd_rf_init_uw2453(struct zd_rf *rf);
#endif /* _ZD_RF_H */
/* zd_rf_uw2453.c: Functions for the UW2453 RF controller
*
* 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
*/
#include <linux/kernel.h>
#include "zd_rf.h"
#include "zd_usb.h"
#include "zd_chip.h"
/* This RF programming code is based upon the code found in v2.16.0.0 of the
* ZyDAS vendor driver. Unlike other RF's, Ubec publish full technical specs
* for this RF on their website, so we're able to understand more than
* usual as to what is going on. Thumbs up for Ubec for doing that. */
/* The 3-wire serial interface provides access to 8 write-only registers.
* The data format is a 4 bit register address followed by a 20 bit value. */
#define UW2453_REGWRITE(reg, val) ((((reg) & 0xf) << 20) | ((val) & 0xfffff))
/* For channel tuning, we have to configure registers 1 (synthesizer), 2 (synth
* fractional divide ratio) and 3 (VCO config).
*
* We configure the RF to produce an interrupt when the PLL is locked onto
* the configured frequency. During initialization, we run through a variety
* of different VCO configurations on channel 1 until we detect a PLL lock.
* When this happens, we remember which VCO configuration produced the lock
* and use it later. Actually, we use the configuration *after* the one that
* produced the lock, which seems odd, but it works.
*
* If we do not see a PLL lock on any standard VCO config, we fall back on an
* autocal configuration, which has a fixed (as opposed to per-channel) VCO
* config and different synth values from the standard set (divide ratio
* is still shared with the standard set). */
/* The per-channel synth values for all standard VCO configurations. These get
* written to register 1. */
static const u8 uw2453_std_synth[] = {
RF_CHANNEL( 1) = 0x47,
RF_CHANNEL( 2) = 0x47,
RF_CHANNEL( 3) = 0x67,
RF_CHANNEL( 4) = 0x67,
RF_CHANNEL( 5) = 0x67,
RF_CHANNEL( 6) = 0x67,
RF_CHANNEL( 7) = 0x57,
RF_CHANNEL( 8) = 0x57,
RF_CHANNEL( 9) = 0x57,
RF_CHANNEL(10) = 0x57,
RF_CHANNEL(11) = 0x77,
RF_CHANNEL(12) = 0x77,
RF_CHANNEL(13) = 0x77,
RF_CHANNEL(14) = 0x4f,
};
/* This table stores the synthesizer fractional divide ratio for *all* VCO
* configurations (both standard and autocal). These get written to register 2.
*/
static const u16 uw2453_synth_divide[] = {
RF_CHANNEL( 1) = 0x999,
RF_CHANNEL( 2) = 0x99b,
RF_CHANNEL( 3) = 0x998,
RF_CHANNEL( 4) = 0x99a,
RF_CHANNEL( 5) = 0x999,
RF_CHANNEL( 6) = 0x99b,
RF_CHANNEL( 7) = 0x998,
RF_CHANNEL( 8) = 0x99a,
RF_CHANNEL( 9) = 0x999,
RF_CHANNEL(10) = 0x99b,
RF_CHANNEL(11) = 0x998,
RF_CHANNEL(12) = 0x99a,
RF_CHANNEL(13) = 0x999,
RF_CHANNEL(14) = 0xccc,
};
/* Here is the data for all the standard VCO configurations. We shrink our
* table a little by observing that both channels in a consecutive pair share
* the same value. We also observe that the high 4 bits ([0:3] in the specs)
* are all 'Reserved' and are always set to 0x4 - we chop them off in the data
* below. */
#define CHAN_TO_PAIRIDX(a) ((a - 1) / 2)
#define RF_CHANPAIR(a,b) [CHAN_TO_PAIRIDX(a)]
static const u16 uw2453_std_vco_cfg[][7] = {
{ /* table 1 */
RF_CHANPAIR( 1, 2) = 0x664d,
RF_CHANPAIR( 3, 4) = 0x604d,
RF_CHANPAIR( 5, 6) = 0x6675,
RF_CHANPAIR( 7, 8) = 0x6475,
RF_CHANPAIR( 9, 10) = 0x6655,
RF_CHANPAIR(11, 12) = 0x6455,
RF_CHANPAIR(13, 14) = 0x6665,
},
{ /* table 2 */
RF_CHANPAIR( 1, 2) = 0x666d,
RF_CHANPAIR( 3, 4) = 0x606d,
RF_CHANPAIR( 5, 6) = 0x664d,
RF_CHANPAIR( 7, 8) = 0x644d,
RF_CHANPAIR( 9, 10) = 0x6675,
RF_CHANPAIR(11, 12) = 0x6475,
RF_CHANPAIR(13, 14) = 0x6655,
},
{ /* table 3 */
RF_CHANPAIR( 1, 2) = 0x665d,
RF_CHANPAIR( 3, 4) = 0x605d,
RF_CHANPAIR( 5, 6) = 0x666d,
RF_CHANPAIR( 7, 8) = 0x646d,
RF_CHANPAIR( 9, 10) = 0x664d,
RF_CHANPAIR(11, 12) = 0x644d,
RF_CHANPAIR(13, 14) = 0x6675,
},
{ /* table 4 */
RF_CHANPAIR( 1, 2) = 0x667d,
RF_CHANPAIR( 3, 4) = 0x607d,
RF_CHANPAIR( 5, 6) = 0x665d,
RF_CHANPAIR( 7, 8) = 0x645d,
RF_CHANPAIR( 9, 10) = 0x666d,
RF_CHANPAIR(11, 12) = 0x646d,
RF_CHANPAIR(13, 14) = 0x664d,
},
{ /* table 5 */
RF_CHANPAIR( 1, 2) = 0x6643,
RF_CHANPAIR( 3, 4) = 0x6043,
RF_CHANPAIR( 5, 6) = 0x667d,
RF_CHANPAIR( 7, 8) = 0x647d,
RF_CHANPAIR( 9, 10) = 0x665d,
RF_CHANPAIR(11, 12) = 0x645d,
RF_CHANPAIR(13, 14) = 0x666d,
},
{ /* table 6 */
RF_CHANPAIR( 1, 2) = 0x6663,
RF_CHANPAIR( 3, 4) = 0x6063,
RF_CHANPAIR( 5, 6) = 0x6643,
RF_CHANPAIR( 7, 8) = 0x6443,
RF_CHANPAIR( 9, 10) = 0x667d,
RF_CHANPAIR(11, 12) = 0x647d,
RF_CHANPAIR(13, 14) = 0x665d,
},
{ /* table 7 */
RF_CHANPAIR( 1, 2) = 0x6653,
RF_CHANPAIR( 3, 4) = 0x6053,
RF_CHANPAIR( 5, 6) = 0x6663,
RF_CHANPAIR( 7, 8) = 0x6463,
RF_CHANPAIR( 9, 10) = 0x6643,
RF_CHANPAIR(11, 12) = 0x6443,
RF_CHANPAIR(13, 14) = 0x667d,
},
{ /* table 8 */
RF_CHANPAIR( 1, 2) = 0x6673,
RF_CHANPAIR( 3, 4) = 0x6073,
RF_CHANPAIR( 5, 6) = 0x6653,
RF_CHANPAIR( 7, 8) = 0x6453,
RF_CHANPAIR( 9, 10) = 0x6663,
RF_CHANPAIR(11, 12) = 0x6463,
RF_CHANPAIR(13, 14) = 0x6643,
},
{ /* table 9 */
RF_CHANPAIR( 1, 2) = 0x664b,
RF_CHANPAIR( 3, 4) = 0x604b,
RF_CHANPAIR( 5, 6) = 0x6673,
RF_CHANPAIR( 7, 8) = 0x6473,
RF_CHANPAIR( 9, 10) = 0x6653,
RF_CHANPAIR(11, 12) = 0x6453,
RF_CHANPAIR(13, 14) = 0x6663,
},
{ /* table 10 */
RF_CHANPAIR( 1, 2) = 0x666b,
RF_CHANPAIR( 3, 4) = 0x606b,
RF_CHANPAIR( 5, 6) = 0x664b,
RF_CHANPAIR( 7, 8) = 0x644b,
RF_CHANPAIR( 9, 10) = 0x6673,
RF_CHANPAIR(11, 12) = 0x6473,
RF_CHANPAIR(13, 14) = 0x6653,
},
{ /* table 11 */
RF_CHANPAIR( 1, 2) = 0x665b,
RF_CHANPAIR( 3, 4) = 0x605b,
RF_CHANPAIR( 5, 6) = 0x666b,
RF_CHANPAIR( 7, 8) = 0x646b,
RF_CHANPAIR( 9, 10) = 0x664b,
RF_CHANPAIR(11, 12) = 0x644b,
RF_CHANPAIR(13, 14) = 0x6673,
},
};
/* The per-channel synth values for autocal. These get written to register 1. */
static const u16 uw2453_autocal_synth[] = {
RF_CHANNEL( 1) = 0x6847,
RF_CHANNEL( 2) = 0x6847,
RF_CHANNEL( 3) = 0x6867,
RF_CHANNEL( 4) = 0x6867,
RF_CHANNEL( 5) = 0x6867,
RF_CHANNEL( 6) = 0x6867,
RF_CHANNEL( 7) = 0x6857,
RF_CHANNEL( 8) = 0x6857,
RF_CHANNEL( 9) = 0x6857,
RF_CHANNEL(10) = 0x6857,
RF_CHANNEL(11) = 0x6877,
RF_CHANNEL(12) = 0x6877,
RF_CHANNEL(13) = 0x6877,
RF_CHANNEL(14) = 0x684f,
};
/* The VCO configuration for autocal (all channels) */
static const u16 UW2453_AUTOCAL_VCO_CFG = 0x6662;
/* TX gain settings. The array index corresponds to the TX power integration
* values found in the EEPROM. The values get written to register 7. */
static u32 uw2453_txgain[] = {
[0x00] = 0x0e313,
[0x01] = 0x0fb13,
[0x02] = 0x0e093,
[0x03] = 0x0f893,
[0x04] = 0x0ea93,
[0x05] = 0x1f093,
[0x06] = 0x1f493,
[0x07] = 0x1f693,
[0x08] = 0x1f393,
[0x09] = 0x1f35b,
[0x0a] = 0x1e6db,
[0x0b] = 0x1ff3f,
[0x0c] = 0x1ffff,
[0x0d] = 0x361d7,
[0x0e] = 0x37fbf,
[0x0f] = 0x3ff8b,
[0x10] = 0x3ff33,
[0x11] = 0x3fb3f,
[0x12] = 0x3ffff,
};
/* RF-specific structure */
struct uw2453_priv {
/* index into synth/VCO config tables where PLL lock was found
* -1 means autocal */
int config;
};
#define UW2453_PRIV(rf) ((struct uw2453_priv *) (rf)->priv)
static int uw2453_synth_set_channel(struct zd_chip *chip, int channel,
bool autocal)
{
int r;
int idx = channel - 1;
u32 val;
if (autocal)
val = UW2453_REGWRITE(1, uw2453_autocal_synth[idx]);
else
val = UW2453_REGWRITE(1, uw2453_std_synth[idx]);
r = zd_rfwrite_locked(chip, val, RF_RV_BITS);
if (r)
return r;
return zd_rfwrite_locked(chip,
UW2453_REGWRITE(2, uw2453_synth_divide[idx]), RF_RV_BITS);
}
static int uw2453_write_vco_cfg(struct zd_chip *chip, u16 value)
{
/* vendor driver always sets these upper bits even though the specs say
* they are reserved */
u32 val = 0x40000 | value;
return zd_rfwrite_locked(chip, UW2453_REGWRITE(3, val), RF_RV_BITS);
}
static int uw2453_init_mode(struct zd_chip *chip)
{
static const u32 rv[] = {
UW2453_REGWRITE(0, 0x25f98), /* enter IDLE mode */
UW2453_REGWRITE(0, 0x25f9a), /* enter CAL_VCO mode */
UW2453_REGWRITE(0, 0x25f94), /* enter RX/TX mode */
UW2453_REGWRITE(0, 0x27fd4), /* power down RSSI circuit */
};
return zd_rfwritev_locked(chip, rv, ARRAY_SIZE(rv), RF_RV_BITS);
}
static int uw2453_set_tx_gain_level(struct zd_chip *chip, int channel)
{
u8 int_value = chip->pwr_int_values[channel - 1];
if (int_value >= ARRAY_SIZE(uw2453_txgain)) {
dev_dbg_f(zd_chip_dev(chip), "can't configure TX gain for "
"int value %x on channel %d\n", int_value, channel);
return 0;
}
return zd_rfwrite_locked(chip,
UW2453_REGWRITE(7, uw2453_txgain[int_value]), RF_RV_BITS);
}
static int uw2453_init_hw(struct zd_rf *rf)
{
int i, r;
int found_config = -1;
u16 intr_status;
struct zd_chip *chip = zd_rf_to_chip(rf);
static const struct zd_ioreq16 ioreqs[] = {
{ CR10, 0x89 }, { CR15, 0x20 },
{ CR17, 0x28 }, /* 6112 no change */
{ CR23, 0x38 }, { CR24, 0x20 }, { CR26, 0x93 },
{ CR27, 0x15 }, { CR28, 0x3e }, { CR29, 0x00 },
{ CR33, 0x28 }, { CR34, 0x30 },
{ CR35, 0x43 }, /* 6112 3e->43 */
{ CR41, 0x24 }, { CR44, 0x32 },
{ CR46, 0x92 }, /* 6112 96->92 */
{ CR47, 0x1e },
{ CR48, 0x04 }, /* 5602 Roger */
{ CR49, 0xfa }, { CR79, 0x58 }, { CR80, 0x30 },
{ CR81, 0x30 }, { CR87, 0x0a }, { CR89, 0x04 },
{ CR91, 0x00 }, { CR92, 0x0a }, { CR98, 0x8d },
{ CR99, 0x28 }, { CR100, 0x02 },
{ CR101, 0x09 }, /* 6112 13->1f 6220 1f->13 6407 13->9 */
{ CR102, 0x27 },
{ CR106, 0x1c }, /* 5d07 5112 1f->1c 6220 1c->1f 6221 1f->1c */
{ CR107, 0x1c }, /* 6220 1c->1a 5221 1a->1c */
{ CR109, 0x13 },
{ CR110, 0x1f }, /* 6112 13->1f 6221 1f->13 6407 13->0x09 */
{ CR111, 0x13 }, { CR112, 0x1f }, { CR113, 0x27 },
{ CR114, 0x23 }, /* 6221 27->23 */
{ CR115, 0x24 }, /* 6112 24->1c 6220 1c->24 */
{ CR116, 0x24 }, /* 6220 1c->24 */
{ CR117, 0xfa }, /* 6112 fa->f8 6220 f8->f4 6220 f4->fa */
{ CR118, 0xf0 }, /* 5d07 6112 f0->f2 6220 f2->f0 */
{ CR119, 0x1a }, /* 6112 1a->10 6220 10->14 6220 14->1a */
{ CR120, 0x4f },
{ CR121, 0x1f }, /* 6220 4f->1f */
{ CR122, 0xf0 }, { CR123, 0x57 }, { CR125, 0xad },
{ CR126, 0x6c }, { CR127, 0x03 },
{ CR128, 0x14 }, /* 6302 12->11 */
{ CR129, 0x12 }, /* 6301 10->0f */
{ CR130, 0x10 }, { CR137, 0x50 }, { CR138, 0xa8 },
{ CR144, 0xac }, { CR146, 0x20 }, { CR252, 0xff },
{ CR253, 0xff },
};
static const u32 rv[] = {
UW2453_REGWRITE(4, 0x2b), /* configure reciever gain */
UW2453_REGWRITE(5, 0x19e4f), /* configure transmitter gain */
UW2453_REGWRITE(6, 0xf81ad), /* enable RX/TX filter tuning */
UW2453_REGWRITE(7, 0x3fffe), /* disable TX gain in test mode */
/* enter CAL_FIL mode, TX gain set by registers, RX gain set by pins,
* RSSI circuit powered down, reduced RSSI range */
UW2453_REGWRITE(0, 0x25f9c), /* 5d01 cal_fil */
/* synthesizer configuration for channel 1 */
UW2453_REGWRITE(1, 0x47),
UW2453_REGWRITE(2, 0x999),
/* disable manual VCO band selection */
UW2453_REGWRITE(3, 0x7602),
/* enable manual VCO band selection, configure current level */
UW2453_REGWRITE(3, 0x46063),
};
r = zd_iowrite16a_locked(chip, ioreqs, ARRAY_SIZE(ioreqs));
if (r)
return r;
r = zd_rfwritev_locked(chip, rv, ARRAY_SIZE(rv), RF_RV_BITS);
if (r)
return r;
r = uw2453_init_mode(chip);
if (r)
return r;
/* Try all standard VCO configuration settings on channel 1 */
for (i = 0; i < ARRAY_SIZE(uw2453_std_vco_cfg) - 1; i++) {
/* Configure synthesizer for channel 1 */
r = uw2453_synth_set_channel(chip, 1, false);
if (r)
return r;
/* Write VCO config */
r = uw2453_write_vco_cfg(chip, uw2453_std_vco_cfg[i][0]);
if (r)
return r;
/* ack interrupt event */
r = zd_iowrite16_locked(chip, 0x0f, UW2453_INTR_REG);
if (r)
return r;
/* check interrupt status */
r = zd_ioread16_locked(chip, &intr_status, UW2453_INTR_REG);
if (r)
return r;
if (!intr_status & 0xf) {
dev_dbg_f(zd_chip_dev(chip),
"PLL locked on configuration %d\n", i);
found_config = i;
break;
}
}
if (found_config == -1) {
/* autocal */
dev_dbg_f(zd_chip_dev(chip),
"PLL did not lock, using autocal\n");
r = uw2453_synth_set_channel(chip, 1, true);
if (r)
return r;
r = uw2453_write_vco_cfg(chip, UW2453_AUTOCAL_VCO_CFG);
if (r)
return r;
}
/* To match the vendor driver behaviour, we use the configuration after
* the one that produced a lock. */
UW2453_PRIV(rf)->config = found_config + 1;
return zd_iowrite16_locked(chip, 0x06, CR203);
}
static int uw2453_set_channel(struct zd_rf *rf, u8 channel)
{
int r;
u16 vco_cfg;
int config = UW2453_PRIV(rf)->config;
bool autocal = (config == -1);
struct zd_chip *chip = zd_rf_to_chip(rf);
static const struct zd_ioreq16 ioreqs[] = {
{ CR80, 0x30 }, { CR81, 0x30 }, { CR79, 0x58 },
{ CR12, 0xf0 }, { CR77, 0x1b }, { CR78, 0x58 },
};
r = uw2453_synth_set_channel(chip, channel, autocal);
if (r)
return r;
if (autocal)
vco_cfg = UW2453_AUTOCAL_VCO_CFG;
else
vco_cfg = uw2453_std_vco_cfg[config][CHAN_TO_PAIRIDX(channel)];
r = uw2453_write_vco_cfg(chip, vco_cfg);
if (r)
return r;
r = uw2453_init_mode(chip);
if (r)
return r;
r = zd_iowrite16a_locked(chip, ioreqs, ARRAY_SIZE(ioreqs));
if (r)
return r;
r = uw2453_set_tx_gain_level(chip, channel);
if (r)
return r;
return zd_iowrite16_locked(chip, 0x06, CR203);
}
static int uw2453_switch_radio_on(struct zd_rf *rf)
{
int r;
struct zd_chip *chip = zd_rf_to_chip(rf);
struct zd_ioreq16 ioreqs[] = {
{ CR11, 0x00 }, { CR251, 0x3f },
};
/* enter RXTX mode */
r = zd_rfwrite_locked(chip, UW2453_REGWRITE(0, 0x25f94), RF_RV_BITS);
if (r)
return r;
if (chip->is_zd1211b)
ioreqs[1].value = 0x7f;
return zd_iowrite16a_locked(chip, ioreqs, ARRAY_SIZE(ioreqs));
}
static int uw2453_switch_radio_off(struct zd_rf *rf)
{
int r;
struct zd_chip *chip = zd_rf_to_chip(rf);
static const struct zd_ioreq16 ioreqs[] = {
{ CR11, 0x04 }, { CR251, 0x2f },
};
/* enter IDLE mode */
/* FIXME: shouldn't we go to SLEEP? sent email to zydas */
r = zd_rfwrite_locked(chip, UW2453_REGWRITE(0, 0x25f90), RF_RV_BITS);
if (r)
return r;
return zd_iowrite16a_locked(chip, ioreqs, ARRAY_SIZE(ioreqs));
}
static void uw2453_clear(struct zd_rf *rf)
{
kfree(rf->priv);
}
int zd_rf_init_uw2453(struct zd_rf *rf)
{
rf->init_hw = uw2453_init_hw;
rf->set_channel = uw2453_set_channel;
rf->switch_radio_on = uw2453_switch_radio_on;
rf->switch_radio_off = uw2453_switch_radio_off;
rf->patch_6m_band_edge = zd_rf_generic_patch_6m;
rf->clear = uw2453_clear;
/* we have our own TX integration code */
rf->update_channel_int = 0;
rf->priv = kmalloc(sizeof(struct uw2453_priv), GFP_KERNEL);
if (rf->priv == NULL)
return -ENOMEM;
return 0;
}
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