From 3c8cd0cce9ab8a25dbcf519cb0de00d2716f8379 Mon Sep 17 00:00:00 2001 From: Pavel Pisa Date: Wed, 6 Dec 2006 17:25:04 +0100 Subject: [PATCH] [ARM] 3992/1: i.MX/MX1 CPU Frequency scaling support Support to change MX1 CPU frequency at runtime. Tested on PiKRON's PiMX1 board and seems to be fully stable up to 200 MHz end even as low as 8 MHz. Signed-off-by: Pavel Pisa Signed-off-by: Russell King --- arch/arm/Kconfig | 11 +- arch/arm/mach-imx/Makefile | 2 + arch/arm/mach-imx/cpufreq.c | 287 ++++++++++++++++++++++++++++ include/asm-arm/arch-imx/imx-regs.h | 10 +- 4 files changed, 306 insertions(+), 4 deletions(-) create mode 100644 arch/arm/mach-imx/cpufreq.c diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 1a59110784..63e7c0c582 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -732,7 +732,7 @@ config XIP_PHYS_ADDR endmenu -if (ARCH_SA1100 || ARCH_INTEGRATOR || ARCH_OMAP) +if (ARCH_SA1100 || ARCH_INTEGRATOR || ARCH_OMAP || ARCH_IMX ) menu "CPU Frequency scaling" @@ -759,6 +759,15 @@ config CPU_FREQ_INTEGRATOR If in doubt, say Y. +config CPU_FREQ_IMX + tristate "CPUfreq driver for i.MX CPUs" + depends on ARCH_IMX && CPU_FREQ + default n + help + This enables the CPUfreq driver for i.MX CPUs. + + If in doubt, say N. + endmenu endif diff --git a/arch/arm/mach-imx/Makefile b/arch/arm/mach-imx/Makefile index 0b27d79f2e..02272aa36e 100644 --- a/arch/arm/mach-imx/Makefile +++ b/arch/arm/mach-imx/Makefile @@ -9,6 +9,8 @@ obj-y += irq.o time.o dma.o generic.o +obj-$(CONFIG_CPU_FREQ_IMX) += cpufreq.o + # Specific board support obj-$(CONFIG_ARCH_MX1ADS) += mx1ads.o diff --git a/arch/arm/mach-imx/cpufreq.c b/arch/arm/mach-imx/cpufreq.c new file mode 100644 index 0000000000..ac5f998956 --- /dev/null +++ b/arch/arm/mach-imx/cpufreq.c @@ -0,0 +1,287 @@ +/* + * cpu.c: clock scaling for the iMX + * + * Copyright (C) 2000 2001, The Delft University of Technology + * Copyright (c) 2004 Sascha Hauer + * Copyright (C) 2006 Inky Lung + * Copyright (C) 2006 Pavel Pisa, PiKRON + * + * 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 +#include +#include +#include +#include + +#include + +#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 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 + * @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, unsigned long freq, int relation) +{ + u32 f_ref = (CSCR & CSCR_SYSTEM_SEL) ? 16000000 : (CLK32 * 512); + 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 = 1; + + 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 + 1000000) { + freq = imx_compute_mpctl(&mpctl0, mpctl0_at_boot, 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; + } + 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 stablized */ + 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->governor = CPUFREQ_DEFAULT_GOVERNOR; + policy->cpuinfo.min_freq = 8000; + policy->cpuinfo.max_freq = 200000; + policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL; + 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) +{ + + 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); + diff --git a/include/asm-arm/arch-imx/imx-regs.h b/include/asm-arm/arch-imx/imx-regs.h index a6912b3d86..e56a4e247d 100644 --- a/include/asm-arm/arch-imx/imx-regs.h +++ b/include/asm-arm/arch-imx/imx-regs.h @@ -41,7 +41,13 @@ /* PLL registers */ #define CSCR __REG(IMX_PLL_BASE) /* Clock Source Control Register */ -#define CSCR_SYSTEM_SEL (1<<16) +#define CSCR_SPLL_RESTART (1<<22) +#define CSCR_MPLL_RESTART (1<<21) +#define CSCR_SYSTEM_SEL (1<<16) +#define CSCR_BCLK_DIV (0xf<<10) +#define CSCR_MPU_PRESC (1<<15) +#define CSCR_SPEN (1<<1) +#define CSCR_MPEN (1<<0) #define MPCTL0 __REG(IMX_PLL_BASE + 0x4) /* MCU PLL Control Register 0 */ #define MPCTL1 __REG(IMX_PLL_BASE + 0x8) /* MCU PLL and System Clock Register 1 */ @@ -49,8 +55,6 @@ #define SPCTL1 __REG(IMX_PLL_BASE + 0x10) /* System PLL Control Register 1 */ #define PCDR __REG(IMX_PLL_BASE + 0x20) /* Peripheral Clock Divider Register */ -#define CSCR_MPLL_RESTART (1<<21) - /* * GPIO Module and I/O Multiplexer * x = 0..3 for reg_A, reg_B, reg_C, reg_D -- 2.39.5