/*
* Copyright (C) 2008 Scientific-Atlanta, Inc.
*
* 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 file comes from kernel/csrc-r4k.c
*/
#include <linux/clocksource.h>
#include <linux/init.h>
#include <asm/time.h> /* Not included in linux/time.h */
#include <asm/mach-powertv/asic_regs.h>
#include "powertv-clock.h"
/* MIPS PLL Register Definitions */
#define PLL_GET_M(x) (((x) >> 8) & 0x000000FF)
#define PLL_GET_N(x) (((x) >> 16) & 0x000000FF)
#define PLL_GET_P(x) (((x) >> 24) & 0x00000007)
/*
* returns: Clock frequency in kHz
*/
unsigned int __init mips_get_pll_freq(void)
{
unsigned int pll_reg, m, n, p;
unsigned int fin = 54000; /* Base frequency in kHz */
unsigned int fout;
/* Read PLL register setting */
pll_reg = asic_read(mips_pll_setup);
m = PLL_GET_M(pll_reg);
n = PLL_GET_N(pll_reg);
p = PLL_GET_P(pll_reg);
pr_info("MIPS PLL Register:0x%x M=%d N=%d P=%d\n", pll_reg, m, n, p);
/* Calculate clock frequency = (2 * N * 54MHz) / (M * (2**P)) */
fout = ((2 * n * fin) / (m * (0x01 << p)));
pr_info("MIPS Clock Freq=%d kHz\n", fout);
return fout;
}
static cycle_t c0_hpt_read(struct clocksource *cs)
{
return read_c0_count();
}
static struct clocksource clocksource_mips = {
.name = "powertv-counter",
.read = c0_hpt_read,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static void __init powertv_c0_hpt_clocksource_init(void)
{
unsigned int pll_freq = mips_get_pll_freq();
pr_info("CPU frequency %d.%02d MHz\n", pll_freq / 1000,
(pll_freq % 1000) * 100 / 1000);
mips_hpt_frequency = pll_freq / 2 * 1000;
clocksource_mips.rating = 200 + mips_hpt_frequency / 10000000;
clocksource_set_clock(&clocksource_mips, mips_hpt_frequency);
clocksource_register(&clocksource_mips);
}
/**
* struct tim_c - free running counter
* @hi: High 16 bits of the counter
* @lo: Low 32 bits of the counter
*
* Lays out the structure of the free running counter in memory. This counter
* increments at a rate of 27 MHz/8 on all platforms.
*/
struct tim_c {
unsigned int hi;
unsigned int lo;
};
static struct tim_c *tim_c;
static cycle_t tim_c_read(struct clocksource *cs)
{
unsigned int hi;
unsigned int next_hi;
unsigned int lo;
hi = readl(&tim_c->hi);
for (;;) {
lo = readl(&tim_c->lo);
next_hi = readl(&tim_c->hi);
if (next_hi == hi)
break;
hi = next_hi;
}
pr_crit("%s: read %llx\n", __func__, ((u64) hi << 32) | lo);
return ((u64) hi << 32) | lo;
}
#define TIM_C_SIZE 48 /* # bits in the timer */
static struct clocksource clocksource_tim_c = {
.name = "powertv-tim_c",
.read = tim_c_read,
.mask = CLOCKSOURCE_MASK(TIM_C_SIZE),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
/**
* powertv_tim_c_clocksource_init - set up a clock source for the TIM_C clock
*
* The hard part here is coming up with a constant k and shift s such that
* the 48-bit TIM_C value multiplied by k doesn't overflow and that value,
* when shifted right by s, yields the corresponding number of nanoseconds.
* We know that TIM_C counts at 27 MHz/8, so each cycle corresponds to
* 1 / (27,000,000/8) seconds. Multiply that by a billion and you get the
* number of nanoseconds. Since the TIM_C value has 48 bits and the math is
* done in 64 bits, avoiding an overflow means that k must be less than
* 64 - 48 = 16 bits.
*/
static void __init powertv_tim_c_clocksource_init(void)
{
int prescale;
unsigned long dividend;
unsigned long k;
int s;
const int max_k_bits = (64 - 48) - 1;
const unsigned long billion = 1000000000;
const unsigned long counts_per_second = 27000000 / 8;
prescale = BITS_PER_LONG - ilog2(billion) - 1;
dividend = billion << prescale;
k = dividend / counts_per_second;
s = ilog2(k) - max_k_bits;
if (s < 0)
s = prescale;
else {
k >>= s;
s += prescale;
}
clocksource_tim_c.mult = k;
clocksource_tim_c.shift = s;
clocksource_tim_c.rating = 200;
clocksource_register(&clocksource_tim_c);
tim_c = (struct tim_c *) asic_reg_addr(tim_ch);
}
/**
powertv_clocksource_init - initialize all clocksources
*/
void __init powertv_clocksource_init(void)
{
powertv_c0_hpt_clocksource_init();
powertv_tim_c_clocksource_init();
}
