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/*
Copyright (C) 2014 Michał Masłowski <mtjm@mtjm.eu>
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 3 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, see <http://www.gnu.org/licenses/>.
*/
/* Try several backlight PWM frequencies and duty cycles to see which
expose the noise on X60 with coreboot.
*/
#include <assert.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <pci/pci.h>
static struct pci_access *pacc;
static uint32_t *map;
static int fd;
#define REGISTER 0x61254
static void
init (void)
{
fd = -1;
/* Find the device. */
struct pci_dev *dev;
pacc = pci_alloc ();
pacc->writeable = 1;
pci_init (pacc);
pci_scan_bus (pacc);
for (dev = pacc->devices; dev != NULL; dev = dev->next)
{
pci_fill_info (dev, PCI_FILL_IDENT | PCI_FILL_BASES);
if (dev->vendor_id != 0x8086 || dev->device_id != 0x27a2)
continue;
break;
}
if (dev == NULL)
{
fprintf (stderr, "Device not found.\n");
goto fail;
}
/* Map a part of its MMIO. */
fd = open ("/dev/mem", O_RDWR);
if (fd == -1)
{
fprintf (stderr, "Cannot open memory. Are you root?\n");
goto fail;
}
map = mmap (NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED, fd, dev->base_addr[0] + (REGISTER & (~4095)));
if (map != MAP_FAILED)
return;
else
perror ("mmap failed");
fail:
if (pacc != NULL)
pci_cleanup (pacc);
if (fd != -1)
close (fd);
exit (1);
}
static void
set_pwm (uint16_t freq, uint16_t duty)
{
assert (duty <= freq);
map[((REGISTER - 4) & 4095) >> 2] = 0x80000000;
map[(REGISTER & 4095) >> 2] = ((freq | 1) << 16) | duty;
}
int
main (void)
{
init ();
int exponent = 8;
int diff = 0;
int divisor = 2;
uint16_t freq = 0x61;
uint16_t duties[] = {
#if 1
// i945
0xf,
0x13,
0x19,
0x1f,
0x23,
0x29,
0x2f,
0x35,
0x39,
0x3f,
0x45,
0x4b,
0x4f,
0x55,
0x5b,
0x61
#else
// gm45
0x2,
0x4,
0x5,
0x7,
0x9,
0xb,
0xd,
0x11,
0x14,
0x17,
0x1c,
0x20,
0x27,
0x31,
0x41,
0x61,
#endif
};
#if 1
for (unsigned int di = 0; di < sizeof (duties) / sizeof (duties[0]); di++)
{
uint16_t duty = duties[di];
#else
for (uint16_t duty = 0; duty < 0x61; duty++)
{
#endif
#if 0
}
#endif
uint16_t pwm_freq = (freq + diff) << exponent;
pwm_freq += (pwm_freq >> divisor);
//pwm_freq |= 0x33;
uint16_t pwm_duty = (duty + diff) << exponent;
pwm_duty += (pwm_duty >> divisor);
//pwm_duty |= 0x32;
set_pwm (pwm_freq, pwm_duty);
sleep (1);
}
if (pacc != NULL)
pci_cleanup (pacc);
if (map != NULL)
munmap (map, 4096);
if (fd != -1)
close (fd);
return 0;
}
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