/* * cpu.c: clock scaling for the iMX * * Copyright (C) 2000 2001, The Delft University of Technology * Copyright (c) 2004 Sascha Hauer <sascha@saschahauer.de> * Copyright (C) 2006 Inky Lung <ilung@cwlinux.com> * Copyright (C) 2006 Pavel Pisa, PiKRON <ppisa@pikron.com> * * Based on SA1100 version written by: * - Johan Pouwelse (J.A.Pouwelse@its.tudelft.nl): initial version * - Erik Mouw (J.A.K.Mouw@its.tudelft.nl): * * 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 * */ /*#define DEBUG*/ #include <linux/kernel.h> #include <linux/types.h> #include <linux/init.h> #include <linux/cpufreq.h> #include <asm/system.h> #include <asm/hardware.h> #include "generic.h" #ifndef __val2mfld #define __val2mfld(mask,val) (((mask)&~((mask)<<1))*(val)&(mask)) #endif #ifndef __mfld2val #define __mfld2val(mask,val) (((val)&(mask))/((mask)&~((mask)<<1))) #endif #define CR_920T_CLOCK_MODE 0xC0000000 #define CR_920T_FASTBUS_MODE 0x00000000 #define CR_920T_ASYNC_MODE 0xC0000000 static u32 mpctl0_at_boot; static u32 bclk_div_at_boot; static void imx_set_async_mode(void) { adjust_cr(CR_920T_CLOCK_MODE, CR_920T_ASYNC_MODE); } static void imx_set_fastbus_mode(void) { adjust_cr(CR_920T_CLOCK_MODE, CR_920T_FASTBUS_MODE); } static void imx_set_mpctl0(u32 mpctl0) { unsigned long flags; if (mpctl0 == 0) { local_irq_save(flags); CSCR &= ~CSCR_MPEN; local_irq_restore(flags); return; } local_irq_save(flags); MPCTL0 = mpctl0; CSCR |= CSCR_MPEN; local_irq_restore(flags); } /** * imx_compute_mpctl - compute new PLL parameters * @new_mpctl: pointer to location assigned by new PLL control register value * @cur_mpctl: current PLL control register parameters * @f_ref: reference source frequency Hz * @freq: required frequency in Hz * @relation: is one of %CPUFREQ_RELATION_L (supremum) * and %CPUFREQ_RELATION_H (infimum) */ long imx_compute_mpctl(u32 *new_mpctl, u32 cur_mpctl, u32 f_ref, unsigned long freq, int relation) { u32 mfi; u32 mfn; u32 mfd; u32 pd; unsigned long long ll; long l; long quot; /* Fdppl=2*Fref*(MFI+MFN/(MFD+1))/(PD+1) */ /* PD=<0,15>, MFD=<1,1023>, MFI=<5,15> MFN=<0,1022> */ if (cur_mpctl) { mfd = ((cur_mpctl >> 16) & 0x3ff) + 1; pd = ((cur_mpctl >> 26) & 0xf) + 1; } else { pd=2; mfd=313; } /* pd=2; mfd=313; mfi=8; mfn=183; */ /* (MFI+MFN/(MFD)) = Fdppl / (2*Fref) * (PD); */ quot = (f_ref + (1 << 9)) >> 10; l = (freq * pd + quot) / (2 * quot); mfi = l >> 10; mfn = ((l & ((1 << 10) - 1)) * mfd + (1 << 9)) >> 10; mfd -= 1; pd -= 1; *new_mpctl = ((mfi & 0xf) << 10) | (mfn & 0x3ff) | ((mfd & 0x3ff) << 16) | ((pd & 0xf) << 26); ll = 2 * (unsigned long long)f_ref * ( (mfi<<16) + (mfn<<16) / (mfd+1) ); quot = (pd+1) * (1<<16); ll += quot / 2; do_div(ll, quot); freq = ll; pr_debug(KERN_DEBUG "imx: new PLL parameters pd=%d mfd=%d mfi=%d mfn=%d, freq=%ld\n", pd, mfd, mfi, mfn, freq); return freq; } static int imx_verify_speed(struct cpufreq_policy *policy) { if (policy->cpu != 0) return -EINVAL; cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, policy->cpuinfo.max_freq); return 0; } static unsigned int imx_get_speed(unsigned int cpu) { unsigned int freq; unsigned int cr; unsigned int cscr; unsigned int bclk_div; if (cpu) return 0; cscr = CSCR; bclk_div = __mfld2val(CSCR_BCLK_DIV, cscr) + 1; cr = get_cr(); if((cr & CR_920T_CLOCK_MODE) == CR_920T_FASTBUS_MODE) { freq = imx_get_system_clk(); freq = (freq + bclk_div/2) / bclk_div; } else { freq = imx_get_mcu_clk(); if (cscr & CSCR_MPU_PRESC) freq /= 2; } freq = (freq + 500) / 1000; return freq; } static int imx_set_target(struct cpufreq_policy *policy, unsigned int target_freq, unsigned int relation) { struct cpufreq_freqs freqs; u32 mpctl0 = 0; u32 cscr; unsigned long flags; long freq; long sysclk; unsigned int bclk_div = bclk_div_at_boot; /* * Some governors do not respects CPU and policy lower limits * which leads to bad things (division by zero etc), ensure * that such things do not happen. */ if(target_freq < policy->cpuinfo.min_freq) target_freq = policy->cpuinfo.min_freq; if(target_freq < policy->min) target_freq = policy->min; freq = target_freq * 1000; pr_debug(KERN_DEBUG "imx: requested frequency %ld Hz, mpctl0 at boot 0x%08x\n", freq, mpctl0_at_boot); sysclk = imx_get_system_clk(); if (freq > sysclk / bclk_div_at_boot + 1000000) { freq = imx_compute_mpctl(&mpctl0, mpctl0_at_boot, CLK32 * 512, freq, relation); if (freq < 0) { printk(KERN_WARNING "imx: target frequency %ld Hz cannot be set\n", freq); return -EINVAL; } } else { if(freq + 1000 < sysclk) { if (relation == CPUFREQ_RELATION_L) bclk_div = (sysclk - 1000) / freq; else bclk_div = (sysclk + freq + 1000) / freq; if(bclk_div > 16) bclk_div = 16; if(bclk_div < bclk_div_at_boot) bclk_div = bclk_div_at_boot; } freq = (sysclk + bclk_div / 2) / bclk_div; } freqs.old = imx_get_speed(0); freqs.new = (freq + 500) / 1000; freqs.cpu = 0; freqs.flags = 0; cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); local_irq_save(flags); imx_set_fastbus_mode(); imx_set_mpctl0(mpctl0); cscr = CSCR; cscr &= ~CSCR_BCLK_DIV; cscr |= __val2mfld(CSCR_BCLK_DIV, bclk_div - 1); CSCR = cscr; if(mpctl0) { CSCR |= CSCR_MPLL_RESTART; /* Wait until MPLL is stabilized */ while( CSCR & CSCR_MPLL_RESTART ); imx_set_async_mode(); } local_irq_restore(flags); cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); pr_debug(KERN_INFO "imx: set frequency %ld Hz, running from %s\n", freq, mpctl0? "MPLL": "SPLL"); return 0; } static int __init imx_cpufreq_driver_init(struct cpufreq_policy *policy) { printk(KERN_INFO "i.MX cpu freq change driver v1.0\n"); if (policy->cpu != 0) return -EINVAL; policy->cur = policy->min = policy->max = imx_get_speed(0); policy->cpuinfo.min_freq = 8000; policy->cpuinfo.max_freq = 200000; /* Manual states, that PLL stabilizes in two CLK32 periods */ policy->cpuinfo.transition_latency = 4 * 1000000000LL / CLK32; return 0; } static struct cpufreq_driver imx_driver = { .flags = CPUFREQ_STICKY, .verify = imx_verify_speed, .target = imx_set_target, .get = imx_get_speed, .init = imx_cpufreq_driver_init, .name = "imx", }; static int __init imx_cpufreq_init(void) { bclk_div_at_boot = __mfld2val(CSCR_BCLK_DIV, CSCR) + 1; mpctl0_at_boot = 0; if((CSCR & CSCR_MPEN) && ((get_cr() & CR_920T_CLOCK_MODE) != CR_920T_FASTBUS_MODE)) mpctl0_at_boot = MPCTL0; return cpufreq_register_driver(&imx_driver); } arch_initcall(imx_cpufreq_init);