- 根目录:
- drivers
- cpufreq
- sa1110-cpufreq.c
/*
* linux/arch/arm/mach-sa1100/cpu-sa1110.c
*
* Copyright (C) 2001 Russell King
*
* 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.
*
* Note: there are two erratas that apply to the SA1110 here:
* 7 - SDRAM auto-power-up failure (rev A0)
* 13 - Corruption of internal register reads/writes following
* SDRAM reads (rev A0, B0, B1)
*
* We ignore rev. A0 and B0 devices; I don't think they're worth supporting.
*
* The SDRAM type can be passed on the command line as cpu_sa1110.sdram=type
*/
#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <asm/cputype.h>
#include <asm/mach-types.h>
#include <mach/generic.h>
#include <mach/hardware.h>
#undef DEBUG
struct sdram_params {
const char name[20];
u_char rows; /* bits */
u_char cas_latency; /* cycles */
u_char tck; /* clock cycle time (ns) */
u_char trcd; /* activate to r/w (ns) */
u_char trp; /* precharge to activate (ns) */
u_char twr; /* write recovery time (ns) */
u_short refresh; /* refresh time for array (us) */
};
struct sdram_info {
u_int mdcnfg;
u_int mdrefr;
u_int mdcas[3];
};
static struct sdram_params sdram_tbl[] __initdata = {
{ /* Toshiba TC59SM716 CL2 */
.name = "TC59SM716-CL2",
.rows = 12,
.tck = 10,
.trcd = 20,
.trp = 20,
.twr = 10,
.refresh = 64000,
.cas_latency = 2,
}, { /* Toshiba TC59SM716 CL3 */
.name = "TC59SM716-CL3",
.rows = 12,
.tck = 8,
.trcd = 20,
.trp = 20,
.twr = 8,
.refresh = 64000,
.cas_latency = 3,
}, { /* Samsung K4S641632D TC75 */
.name = "K4S641632D",
.rows = 14,
.tck = 9,
.trcd = 27,
.trp = 20,
.twr = 9,
.refresh = 64000,
.cas_latency = 3,
}, { /* Samsung K4S281632B-1H */
.name = "K4S281632B-1H",
.rows = 12,
.tck = 10,
.trp = 20,
.twr = 10,
.refresh = 64000,
.cas_latency = 3,
}, { /* Samsung KM416S4030CT */
.name = "KM416S4030CT",
.rows = 13,
.tck = 8,
.trcd = 24, /* 3 CLKs */
.trp = 24, /* 3 CLKs */
.twr = 16, /* Trdl: 2 CLKs */
.refresh = 64000,
.cas_latency = 3,
}, { /* Winbond W982516AH75L CL3 */
.name = "W982516AH75L",
.rows = 16,
.tck = 8,
.trcd = 20,
.trp = 20,
.twr = 8,
.refresh = 64000,
.cas_latency = 3,
}, { /* Micron MT48LC8M16A2TG-75 */
.name = "MT48LC8M16A2TG-75",
.rows = 12,
.tck = 8,
.trcd = 20,
.trp = 20,
.twr = 8,
.refresh = 64000,
.cas_latency = 3,
},
};
static struct sdram_params sdram_params;
/*
* Given a period in ns and frequency in khz, calculate the number of
* cycles of frequency in period. Note that we round up to the next
* cycle, even if we are only slightly over.
*/
static inline u_int ns_to_cycles(u_int ns, u_int khz)
{
return (ns * khz + 999999) / 1000000;
}
/*
* Create the MDCAS register bit pattern.
*/
static inline void set_mdcas(u_int *mdcas, int delayed, u_int rcd)
{
u_int shift;
rcd = 2 * rcd - 1;
shift = delayed + 1 + rcd;
mdcas[0] = (1 << rcd) - 1;
mdcas[0] |= 0x55555555 << shift;
mdcas[1] = mdcas[2] = 0x55555555 << (shift & 1);
}
static void
sdram_calculate_timing(struct sdram_info *sd, u_int cpu_khz,
struct sdram_params *sdram)
{
u_int mem_khz, sd_khz, trp, twr;
mem_khz = cpu_khz / 2;
sd_khz = mem_khz;
/*
* If SDCLK would invalidate the SDRAM timings,
* run SDCLK at half speed.
*
* CPU steppings prior to B2 must either run the memory at
* half speed or use delayed read latching (errata 13).
*/
if ((ns_to_cycles(sdram->tck, sd_khz) > 1) ||
(CPU_REVISION < CPU_SA1110_B2 && sd_khz < 62000))
sd_khz /= 2;
sd->mdcnfg = MDCNFG & 0x007f007f;
twr = ns_to_cycles(sdram->twr, mem_khz);
/* trp should always be >1 */
trp = ns_to_cycles(sdram->trp, mem_khz) - 1;
if (trp < 1)
trp = 1;
sd->mdcnfg |= trp << 8;
sd->mdcnfg |= trp << 24;
sd->mdcnfg |= sdram->cas_latency << 12;
sd->mdcnfg |= sdram->cas_latency << 28;
sd->mdcnfg |= twr << 14;
sd->mdcnfg |= twr << 30;
sd->mdrefr = MDREFR & 0xffbffff0;
sd->mdrefr |= 7;
if (sd_khz != mem_khz)
sd->mdrefr |= MDREFR_K1DB2;
/* initial number of '1's in MDCAS + 1 */
set_mdcas(sd->mdcas, sd_khz >= 62000,
ns_to_cycles(sdram->trcd, mem_khz));
#ifdef DEBUG
printk(KERN_DEBUG "MDCNFG: %08x MDREFR: %08x MDCAS0: %08x MDCAS1: %08x MDCAS2: %08x\n",
sd->mdcnfg, sd->mdrefr, sd->mdcas[0], sd->mdcas[1],
sd->mdcas[2]);
#endif
}
/*
* Set the SDRAM refresh rate.
*/
static inline void sdram_set_refresh(u_int dri)
{
MDREFR = (MDREFR & 0xffff000f) | (dri << 4);
(void) MDREFR;
}
/*
* Update the refresh period. We do this such that we always refresh
* the SDRAMs within their permissible period. The refresh period is
* always a multiple of the memory clock (fixed at cpu_clock / 2).
*
* FIXME: we don't currently take account of burst accesses here,
* but neither do Intels DM nor Angel.
*/
static void
sdram_update_refresh(u_int cpu_khz, struct sdram_params *sdram)
{
u_int ns_row = (sdram->refresh * 1000) >> sdram->rows;
u_int dri = ns_to_cycles(ns_row, cpu_khz / 2) / 32;
#ifdef DEBUG
mdelay(250);
printk(KERN_DEBUG "new dri value = %d\n", dri);
#endif
sdram_set_refresh(dri);
}
/*
* Ok, set the CPU frequency.
*/
static int sa1110_target(struct cpufreq_policy *policy, unsigned int ppcr)
{
struct sdram_params *sdram = &sdram_params;
struct sdram_info sd;
unsigned long flags;
unsigned int unused;
sdram_calculate_timing(&sd, sa11x0_freq_table[ppcr].frequency, sdram);
#if 0
/*
* These values are wrong according to the SA1110 documentation
* and errata, but they seem to work. Need to get a storage
* scope on to the SDRAM signals to work out why.
*/
if (policy->max < 147500) {
sd.mdrefr |= MDREFR_K1DB2;
sd.mdcas[0] = 0xaaaaaa7f;
} else {
sd.mdrefr &= ~MDREFR_K1DB2;
sd.mdcas[0] = 0xaaaaaa9f;
}
sd.mdcas[1] = 0xaaaaaaaa;
sd.mdcas[2] = 0xaaaaaaaa;
#endif
/*
* The clock could be going away for some time. Set the SDRAMs
* to refresh rapidly (every 64 memory clock cycles). To get
* through the whole array, we need to wait 262144 mclk cycles.
* We wait 20ms to be safe.
*/
sdram_set_refresh(2);
if (!irqs_disabled())
msleep(20);
else
mdelay(20);
/*
* Reprogram the DRAM timings with interrupts disabled, and
* ensure that we are doing this within a complete cache line.
* This means that we won't access SDRAM for the duration of
* the programming.
*/
local_irq_save(flags);
asm("mcr p15, 0, %0, c7, c10, 4" : : "r" (0));
udelay(10);
__asm__ __volatile__("\n\
b 2f \n\
.align 5 \n\
1: str %3, [%1, #0] @ MDCNFG \n\
str %4, [%1, #28] @ MDREFR \n\
str %5, [%1, #4] @ MDCAS0 \n\
str %6, [%1, #8] @ MDCAS1 \n\
str %7, [%1, #12] @ MDCAS2 \n\
str %8, [%2, #0] @ PPCR \n\
ldr %0, [%1, #0] \n\
b 3f \n\
2: b 1b \n\
3: nop \n\
nop"
: "=&r" (unused)
: "r" (&MDCNFG), "r" (&PPCR), "0" (sd.mdcnfg),
"r" (sd.mdrefr), "r" (sd.mdcas[0]),
"r" (sd.mdcas[1]), "r" (sd.mdcas[2]), "r" (ppcr));
local_irq_restore(flags);
/*
* Now, return the SDRAM refresh back to normal.
*/
sdram_update_refresh(sa11x0_freq_table[ppcr].frequency, sdram);
return 0;
}
static int __init sa1110_cpu_init(struct cpufreq_policy *policy)
{
return cpufreq_generic_init(policy, sa11x0_freq_table, CPUFREQ_ETERNAL);
}
/* sa1110_driver needs __refdata because it must remain after init registers
* it with cpufreq_register_driver() */
static struct cpufreq_driver sa1110_driver __refdata = {
.flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
.verify = cpufreq_generic_frequency_table_verify,
.target_index = sa1110_target,
.get = sa11x0_getspeed,
.init = sa1110_cpu_init,
.name = "sa1110",
};
static struct sdram_params *sa1110_find_sdram(const char *name)
{
struct sdram_params *sdram;
for (sdram = sdram_tbl; sdram < sdram_tbl + ARRAY_SIZE(sdram_tbl);
sdram++)
if (strcmp(name, sdram->name) == 0)
return sdram;
return NULL;
}
static char sdram_name[16];
static int __init sa1110_clk_init(void)
{
struct sdram_params *sdram;
const char *name = sdram_name;
if (!cpu_is_sa1110())
return -ENODEV;
if (!name[0]) {
if (machine_is_assabet())
name = "TC59SM716-CL3";
if (machine_is_pt_system3())
name = "K4S641632D";
if (machine_is_h3100())
name = "KM416S4030CT";
if (machine_is_jornada720() || machine_is_h3600())
name = "K4S281632B-1H";
if (machine_is_nanoengine())
name = "MT48LC8M16A2TG-75";
}
sdram = sa1110_find_sdram(name);
if (sdram) {
printk(KERN_DEBUG "SDRAM: tck: %d trcd: %d trp: %d"
" twr: %d refresh: %d cas_latency: %d\n",
sdram->tck, sdram->trcd, sdram->trp,
sdram->twr, sdram->refresh, sdram->cas_latency);
memcpy(&sdram_params, sdram, sizeof(sdram_params));
return cpufreq_register_driver(&sa1110_driver);
}
return 0;
}
module_param_string(sdram, sdram_name, sizeof(sdram_name), 0);
arch_initcall(sa1110_clk_init);