/*
* Copyright (c) 2006-2009 Simtec Electronics
* http://armlinux.simtec.co.uk/
* Ben Dooks <ben@simtec.co.uk>
* Vincent Sanders <vince@simtec.co.uk>
*
* S3C2440/S3C2442 CPU Frequency scaling
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/cpufreq.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <asm/mach/arch.h>
#include <asm/mach/map.h>
#include <mach/regs-clock.h>
#include <plat/cpu.h>
#include <plat/cpu-freq-core.h>
#include <plat/clock.h>
static struct clk *xtal;
static struct clk *fclk;
static struct clk *hclk;
static struct clk *armclk;
/* HDIV: 1, 2, 3, 4, 6, 8 */
static inline int within_khz(unsigned long a, unsigned long b)
{
long diff = a - b;
return (diff >= -1000 && diff <= 1000);
}
/**
* s3c2440_cpufreq_calcdivs - calculate divider settings
* @cfg: The cpu frequency settings.
*
* Calcualte the divider values for the given frequency settings
* specified in @cfg. The values are stored in @cfg for later use
* by the relevant set routine if the request settings can be reached.
*/
static int s3c2440_cpufreq_calcdivs(struct s3c_cpufreq_config *cfg)
{
unsigned int hdiv, pdiv;
unsigned long hclk, fclk, armclk;
unsigned long hclk_max;
fclk = cfg->freq.fclk;
armclk = cfg->freq.armclk;
hclk_max = cfg->max.hclk;
s3c_freq_dbg("%s: fclk is %lu, armclk %lu, max hclk %lu\n",
__func__, fclk, armclk, hclk_max);
if (armclk > fclk) {
printk(KERN_WARNING "%s: armclk > fclk\n", __func__);
armclk = fclk;
}
/* if we are in DVS, we need HCLK to be <= ARMCLK */
if (armclk < fclk && armclk < hclk_max)
hclk_max = armclk;
for (hdiv = 1; hdiv < 9; hdiv++) {
if (hdiv == 5 || hdiv == 7)
hdiv++;
hclk = (fclk / hdiv);
if (hclk <= hclk_max || within_khz(hclk, hclk_max))
break;
}
s3c_freq_dbg("%s: hclk %lu, div %d\n", __func__, hclk, hdiv);
if (hdiv > 8)
goto invalid;
pdiv = (hclk > cfg->max.pclk) ? 2 : 1;
if ((hclk / pdiv) > cfg->max.pclk)
pdiv++;
s3c_freq_dbg("%s: pdiv %d\n", __func__, pdiv);
if (pdiv > 2)
goto invalid;
pdiv *= hdiv;
/* calculate a valid armclk */
if (armclk < hclk)
armclk = hclk;
/* if we're running armclk lower than fclk, this really means
* that the system should go into dvs mode, which means that
* armclk is connected to hclk. */
if (armclk < fclk) {
cfg->divs.dvs = 1;
armclk = hclk;
} else
cfg->divs.dvs = 0;
cfg->freq.armclk = armclk;
/* store the result, and then return */
cfg->divs.h_divisor = hdiv;
cfg->divs.p_divisor = pdiv;
return 0;
invalid:
return -EINVAL;
}
#define CAMDIVN_HCLK_HALF (S3C2440_CAMDIVN_HCLK3_HALF | \
S3C2440_CAMDIVN_HCLK4_HALF)
/**
* s3c2440_cpufreq_setdivs - set the cpu frequency divider settings
* @cfg: The cpu frequency settings.
*
* Set the divisors from the settings in @cfg, which where generated
* during the calculation phase by s3c2440_cpufreq_calcdivs().
*/
static void s3c2440_cpufreq_setdivs(struct s3c_cpufreq_config *cfg)
{
unsigned long clkdiv, camdiv;
s3c_freq_dbg("%s: divsiors: h=%d, p=%d\n", __func__,
cfg->divs.h_divisor, cfg->divs.p_divisor);
clkdiv = __raw_readl(S3C2410_CLKDIVN);
camdiv = __raw_readl(S3C2440_CAMDIVN);
clkdiv &= ~(S3C2440_CLKDIVN_HDIVN_MASK | S3C2440_CLKDIVN_PDIVN);
camdiv &= ~CAMDIVN_HCLK_HALF;
switch (cfg->divs.h_divisor) {
case 1:
clkdiv |= S3C2440_CLKDIVN_HDIVN_1;
break;
case 2:
clkdiv |= S3C2440_CLKDIVN_HDIVN_2;
break;
case 6:
camdiv |= S3C2440_CAMDIVN_HCLK3_HALF;
case 3:
clkdiv |= S3C2440_CLKDIVN_HDIVN_3_6;
break;
case 8:
camdiv |= S3C2440_CAMDIVN_HCLK4_HALF;
case 4:
clkdiv |= S3C2440_CLKDIVN_HDIVN_4_8;
break;
default:
BUG(); /* we don't expect to get here. */
}
if (cfg->divs.p_divisor != cfg->divs.h_divisor)
clkdiv |= S3C2440_CLKDIVN_PDIVN;
/* todo - set pclk. */
/* Write the divisors first with hclk intentionally halved so that
* when we write clkdiv we will under-frequency instead of over. We
* then make a short delay and remove the hclk halving if necessary.
*/
__raw_writel(camdiv | CAMDIVN_HCLK_HALF, S3C2440_CAMDIVN);
__raw_writel(clkdiv, S3C2410_CLKDIVN);
ndelay(20);
__raw_writel(camdiv, S3C2440_CAMDIVN);
clk_set_parent(armclk, cfg->divs.dvs ? hclk : fclk);
}
static int run_freq_for(unsigned long max_hclk, unsigned long fclk,
int *divs,
struct cpufreq_frequency_table *table,
size_t table_size)
{
unsigned long freq;
int index = 0;
int div;
for (div = *divs; div > 0; div = *divs++) {
freq = fclk / div;
if (freq > max_hclk && div != 1)
continue;
freq /= 1000; /* table is in kHz */
index = s3c_cpufreq_addfreq(table, index, table_size, freq);
if (index < 0)
break;
}
return index;
}
static int hclk_divs[] = { 1, 2, 3, 4, 6, 8, -1 };
static int s3c2440_cpufreq_calctable(struct s3c_cpufreq_config *cfg,
struct cpufreq_frequency_table *table,
size_t table_size)
{
int ret;
WARN_ON(cfg->info == NULL);
WARN_ON(cfg->board == NULL);
ret = run_freq_for(cfg->info->max.hclk,
cfg->info->max.fclk,
hclk_divs,
table, table_size);
s3c_freq_dbg("%s: returning %d\n", __func__, ret);
return ret;
}
static struct s3c_cpufreq_info s3c2440_cpufreq_info = {
.max = {
.fclk = 400000000,
.hclk = 133333333,
.pclk = 66666666,
},
.locktime_m = 300,
.locktime_u = 300,
.locktime_bits = 16,
.name = "s3c244x",
.calc_iotiming = s3c2410_iotiming_calc,
.set_iotiming = s3c2410_iotiming_set,
.get_iotiming = s3c2410_iotiming_get,
.set_fvco = s3c2410_set_fvco,
.set_refresh = s3c2410_cpufreq_setrefresh,
.set_divs = s3c2440_cpufreq_setdivs,
.calc_divs = s3c2440_cpufreq_calcdivs,
.calc_freqtable = s3c2440_cpufreq_calctable,
.resume_clocks = s3c244x_setup_clocks,
.debug_io_show = s3c_cpufreq_debugfs_call(s3c2410_iotiming_debugfs),
};
static int s3c2440_cpufreq_add(struct device *dev,
struct subsys_interface *sif)
{
xtal = s3c_cpufreq_clk_get(NULL, "xtal");
hclk = s3c_cpufreq_clk_get(NULL, "hclk");
fclk = s3c_cpufreq_clk_get(NULL, "fclk");
armclk = s3c_cpufreq_clk_get(NULL, "armclk");
if (IS_ERR(xtal) || IS_ERR(hclk) || IS_ERR(fclk) || IS_ERR(armclk)) {
printk(KERN_ERR "%s: failed to get clocks\n", __func__);
return -ENOENT;
}
return s3c_cpufreq_register(&s3c2440_cpufreq_info);
}
static struct subsys_interface s3c2440_cpufreq_interface = {
.name = "s3c2440_cpufreq",
.subsys = &s3c2440_subsys,
.add_dev = s3c2440_cpufreq_add,
};
static int s3c2440_cpufreq_init(void)
{
return subsys_interface_register(&s3c2440_cpufreq_interface);
}
/* arch_initcall adds the clocks we need, so use subsys_initcall. */
subsys_initcall(s3c2440_cpufreq_init);
static struct subsys_interface s3c2442_cpufreq_interface = {
.name = "s3c2442_cpufreq",
.subsys = &s3c2442_subsys,
.add_dev = s3c2440_cpufreq_add,
};
static int s3c2442_cpufreq_init(void)
{
return subsys_interface_register(&s3c2442_cpufreq_interface);
}
subsys_initcall(s3c2442_cpufreq_init);
