diff options
Diffstat (limited to 'drivers/cpufreq/sa1110-cpufreq.c')
| -rw-r--r-- | drivers/cpufreq/sa1110-cpufreq.c | 375 |
1 files changed, 375 insertions, 0 deletions
diff --git a/drivers/cpufreq/sa1110-cpufreq.c b/drivers/cpufreq/sa1110-cpufreq.c new file mode 100644 index 000000000..66e5fb088 --- /dev/null +++ b/drivers/cpufreq/sa1110-cpufreq.c @@ -0,0 +1,375 @@ +/* + * 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) || + (read_cpuid_revision() < ARM_CPU_REV_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, 0); +} + +/* 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 | + CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING, + .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); |