diff options
Diffstat (limited to 'arch/arm/plat-s3c24xx/s3c2440-cpufreq.c')
| -rw-r--r-- | arch/arm/plat-s3c24xx/s3c2440-cpufreq.c | 309 |
1 files changed, 309 insertions, 0 deletions
diff --git a/arch/arm/plat-s3c24xx/s3c2440-cpufreq.c b/arch/arm/plat-s3c24xx/s3c2440-cpufreq.c new file mode 100644 index 00000000000..c177a20319e --- /dev/null +++ b/arch/arm/plat-s3c24xx/s3c2440-cpufreq.c @@ -0,0 +1,309 @@ +/* linux/arch/arm/plat-s3c24xx/s3c2440-cpufreq.c + * + * Copyright (c) 2006,2008,2009 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/sysdev.h> +#include <linux/delay.h> +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/io.h> + +#include <mach/hardware.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. + */ +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; +} + +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, +}; + +static int s3c2440_cpufreq_add(struct sys_device *sysdev) +{ + 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 sysdev_driver s3c2440_cpufreq_driver = { + .add = s3c2440_cpufreq_add, +}; + +static int s3c2440_cpufreq_init(void) +{ + return sysdev_driver_register(&s3c2440_sysclass, + &s3c2440_cpufreq_driver); +} + +/* arch_initcall adds the clocks we need, so use subsys_initcall. */ +subsys_initcall(s3c2440_cpufreq_init); + +static struct sysdev_driver s3c2442_cpufreq_driver = { + .add = s3c2440_cpufreq_add, +}; + +static int s3c2442_cpufreq_init(void) +{ + return sysdev_driver_register(&s3c2442_sysclass, + &s3c2442_cpufreq_driver); +} + +subsys_initcall(s3c2442_cpufreq_init); |