diff options
Diffstat (limited to 'kernel/drivers/cpufreq/s3c64xx-cpufreq.c')
| -rw-r--r-- | kernel/drivers/cpufreq/s3c64xx-cpufreq.c | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/kernel/drivers/cpufreq/s3c64xx-cpufreq.c b/kernel/drivers/cpufreq/s3c64xx-cpufreq.c new file mode 100644 index 000000000..176e84cc3 --- /dev/null +++ b/kernel/drivers/cpufreq/s3c64xx-cpufreq.c @@ -0,0 +1,227 @@ +/* + * Copyright 2009 Wolfson Microelectronics plc + * + * S3C64xx CPUfreq Support + * + * 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. + */ + +#define pr_fmt(fmt) "cpufreq: " fmt + +#include <linux/kernel.h> +#include <linux/types.h> +#include <linux/init.h> +#include <linux/cpufreq.h> +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/regulator/consumer.h> +#include <linux/module.h> + +static struct regulator *vddarm; +static unsigned long regulator_latency; + +#ifdef CONFIG_CPU_S3C6410 +struct s3c64xx_dvfs { + unsigned int vddarm_min; + unsigned int vddarm_max; +}; + +static struct s3c64xx_dvfs s3c64xx_dvfs_table[] = { + [0] = { 1000000, 1150000 }, + [1] = { 1050000, 1150000 }, + [2] = { 1100000, 1150000 }, + [3] = { 1200000, 1350000 }, + [4] = { 1300000, 1350000 }, +}; + +static struct cpufreq_frequency_table s3c64xx_freq_table[] = { + { 0, 0, 66000 }, + { 0, 0, 100000 }, + { 0, 0, 133000 }, + { 0, 1, 200000 }, + { 0, 1, 222000 }, + { 0, 1, 266000 }, + { 0, 2, 333000 }, + { 0, 2, 400000 }, + { 0, 2, 532000 }, + { 0, 2, 533000 }, + { 0, 3, 667000 }, + { 0, 4, 800000 }, + { 0, 0, CPUFREQ_TABLE_END }, +}; +#endif + +static int s3c64xx_cpufreq_set_target(struct cpufreq_policy *policy, + unsigned int index) +{ + struct s3c64xx_dvfs *dvfs; + unsigned int old_freq, new_freq; + int ret; + + old_freq = clk_get_rate(policy->clk) / 1000; + new_freq = s3c64xx_freq_table[index].frequency; + dvfs = &s3c64xx_dvfs_table[s3c64xx_freq_table[index].driver_data]; + +#ifdef CONFIG_REGULATOR + if (vddarm && new_freq > old_freq) { + ret = regulator_set_voltage(vddarm, + dvfs->vddarm_min, + dvfs->vddarm_max); + if (ret != 0) { + pr_err("Failed to set VDDARM for %dkHz: %d\n", + new_freq, ret); + return ret; + } + } +#endif + + ret = clk_set_rate(policy->clk, new_freq * 1000); + if (ret < 0) { + pr_err("Failed to set rate %dkHz: %d\n", + new_freq, ret); + return ret; + } + +#ifdef CONFIG_REGULATOR + if (vddarm && new_freq < old_freq) { + ret = regulator_set_voltage(vddarm, + dvfs->vddarm_min, + dvfs->vddarm_max); + if (ret != 0) { + pr_err("Failed to set VDDARM for %dkHz: %d\n", + new_freq, ret); + if (clk_set_rate(policy->clk, old_freq * 1000) < 0) + pr_err("Failed to restore original clock rate\n"); + + return ret; + } + } +#endif + + pr_debug("Set actual frequency %lukHz\n", + clk_get_rate(policy->clk) / 1000); + + return 0; +} + +#ifdef CONFIG_REGULATOR +static void __init s3c64xx_cpufreq_config_regulator(void) +{ + int count, v, i, found; + struct cpufreq_frequency_table *freq; + struct s3c64xx_dvfs *dvfs; + + count = regulator_count_voltages(vddarm); + if (count < 0) { + pr_err("Unable to check supported voltages\n"); + } + + if (!count) + goto out; + + cpufreq_for_each_valid_entry(freq, s3c64xx_freq_table) { + dvfs = &s3c64xx_dvfs_table[freq->driver_data]; + found = 0; + + for (i = 0; i < count; i++) { + v = regulator_list_voltage(vddarm, i); + if (v >= dvfs->vddarm_min && v <= dvfs->vddarm_max) + found = 1; + } + + if (!found) { + pr_debug("%dkHz unsupported by regulator\n", + freq->frequency); + freq->frequency = CPUFREQ_ENTRY_INVALID; + } + } + +out: + /* Guess based on having to do an I2C/SPI write; in future we + * will be able to query the regulator performance here. */ + regulator_latency = 1 * 1000 * 1000; +} +#endif + +static int s3c64xx_cpufreq_driver_init(struct cpufreq_policy *policy) +{ + int ret; + struct cpufreq_frequency_table *freq; + + if (policy->cpu != 0) + return -EINVAL; + + if (s3c64xx_freq_table == NULL) { + pr_err("No frequency information for this CPU\n"); + return -ENODEV; + } + + policy->clk = clk_get(NULL, "armclk"); + if (IS_ERR(policy->clk)) { + pr_err("Unable to obtain ARMCLK: %ld\n", + PTR_ERR(policy->clk)); + return PTR_ERR(policy->clk); + } + +#ifdef CONFIG_REGULATOR + vddarm = regulator_get(NULL, "vddarm"); + if (IS_ERR(vddarm)) { + ret = PTR_ERR(vddarm); + pr_err("Failed to obtain VDDARM: %d\n", ret); + pr_err("Only frequency scaling available\n"); + vddarm = NULL; + } else { + s3c64xx_cpufreq_config_regulator(); + } +#endif + + cpufreq_for_each_entry(freq, s3c64xx_freq_table) { + unsigned long r; + + /* Check for frequencies we can generate */ + r = clk_round_rate(policy->clk, freq->frequency * 1000); + r /= 1000; + if (r != freq->frequency) { + pr_debug("%dkHz unsupported by clock\n", + freq->frequency); + freq->frequency = CPUFREQ_ENTRY_INVALID; + } + + /* If we have no regulator then assume startup + * frequency is the maximum we can support. */ + if (!vddarm && freq->frequency > clk_get_rate(policy->clk) / 1000) + freq->frequency = CPUFREQ_ENTRY_INVALID; + } + + /* Datasheet says PLL stabalisation time (if we were to use + * the PLLs, which we don't currently) is ~300us worst case, + * but add some fudge. + */ + ret = cpufreq_generic_init(policy, s3c64xx_freq_table, + (500 * 1000) + regulator_latency); + if (ret != 0) { + pr_err("Failed to configure frequency table: %d\n", + ret); + regulator_put(vddarm); + clk_put(policy->clk); + } + + return ret; +} + +static struct cpufreq_driver s3c64xx_cpufreq_driver = { + .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK, + .verify = cpufreq_generic_frequency_table_verify, + .target_index = s3c64xx_cpufreq_set_target, + .get = cpufreq_generic_get, + .init = s3c64xx_cpufreq_driver_init, + .name = "s3c", +}; + +static int __init s3c64xx_cpufreq_init(void) +{ + return cpufreq_register_driver(&s3c64xx_cpufreq_driver); +} +module_init(s3c64xx_cpufreq_init); |