diff options
Diffstat (limited to 'drivers/cpufreq/s3c2416-cpufreq.c')
| -rw-r--r-- | drivers/cpufreq/s3c2416-cpufreq.c | 492 |
1 files changed, 492 insertions, 0 deletions
diff --git a/drivers/cpufreq/s3c2416-cpufreq.c b/drivers/cpufreq/s3c2416-cpufreq.c new file mode 100644 index 000000000..5c221bc90 --- /dev/null +++ b/drivers/cpufreq/s3c2416-cpufreq.c @@ -0,0 +1,492 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * S3C2416/2450 CPUfreq Support + * + * Copyright 2011 Heiko Stuebner <heiko@sntech.de> + * + * based on s3c64xx_cpufreq.c + * + * Copyright 2009 Wolfson Microelectronics plc + */ + +#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/reboot.h> +#include <linux/module.h> + +static DEFINE_MUTEX(cpufreq_lock); + +struct s3c2416_data { + struct clk *armdiv; + struct clk *armclk; + struct clk *hclk; + + unsigned long regulator_latency; +#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE + struct regulator *vddarm; +#endif + + struct cpufreq_frequency_table *freq_table; + + bool is_dvs; + bool disable_dvs; +}; + +static struct s3c2416_data s3c2416_cpufreq; + +struct s3c2416_dvfs { + unsigned int vddarm_min; + unsigned int vddarm_max; +}; + +/* pseudo-frequency for dvs mode */ +#define FREQ_DVS 132333 + +/* frequency to sleep and reboot in + * it's essential to leave dvs, as some boards do not reconfigure the + * regulator on reboot + */ +#define FREQ_SLEEP 133333 + +/* Sources for the ARMCLK */ +#define SOURCE_HCLK 0 +#define SOURCE_ARMDIV 1 + +#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE +/* S3C2416 only supports changing the voltage in the dvs-mode. + * Voltages down to 1.0V seem to work, so we take what the regulator + * can get us. + */ +static struct s3c2416_dvfs s3c2416_dvfs_table[] = { + [SOURCE_HCLK] = { 950000, 1250000 }, + [SOURCE_ARMDIV] = { 1250000, 1350000 }, +}; +#endif + +static struct cpufreq_frequency_table s3c2416_freq_table[] = { + { 0, SOURCE_HCLK, FREQ_DVS }, + { 0, SOURCE_ARMDIV, 133333 }, + { 0, SOURCE_ARMDIV, 266666 }, + { 0, SOURCE_ARMDIV, 400000 }, + { 0, 0, CPUFREQ_TABLE_END }, +}; + +static struct cpufreq_frequency_table s3c2450_freq_table[] = { + { 0, SOURCE_HCLK, FREQ_DVS }, + { 0, SOURCE_ARMDIV, 133500 }, + { 0, SOURCE_ARMDIV, 267000 }, + { 0, SOURCE_ARMDIV, 534000 }, + { 0, 0, CPUFREQ_TABLE_END }, +}; + +static unsigned int s3c2416_cpufreq_get_speed(unsigned int cpu) +{ + struct s3c2416_data *s3c_freq = &s3c2416_cpufreq; + + if (cpu != 0) + return 0; + + /* return our pseudo-frequency when in dvs mode */ + if (s3c_freq->is_dvs) + return FREQ_DVS; + + return clk_get_rate(s3c_freq->armclk) / 1000; +} + +static int s3c2416_cpufreq_set_armdiv(struct s3c2416_data *s3c_freq, + unsigned int freq) +{ + int ret; + + if (clk_get_rate(s3c_freq->armdiv) / 1000 != freq) { + ret = clk_set_rate(s3c_freq->armdiv, freq * 1000); + if (ret < 0) { + pr_err("cpufreq: Failed to set armdiv rate %dkHz: %d\n", + freq, ret); + return ret; + } + } + + return 0; +} + +static int s3c2416_cpufreq_enter_dvs(struct s3c2416_data *s3c_freq, int idx) +{ +#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE + struct s3c2416_dvfs *dvfs; +#endif + int ret; + + if (s3c_freq->is_dvs) { + pr_debug("cpufreq: already in dvs mode, nothing to do\n"); + return 0; + } + + pr_debug("cpufreq: switching armclk to hclk (%lukHz)\n", + clk_get_rate(s3c_freq->hclk) / 1000); + ret = clk_set_parent(s3c_freq->armclk, s3c_freq->hclk); + if (ret < 0) { + pr_err("cpufreq: Failed to switch armclk to hclk: %d\n", ret); + return ret; + } + +#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE + /* changing the core voltage is only allowed when in dvs mode */ + if (s3c_freq->vddarm) { + dvfs = &s3c2416_dvfs_table[idx]; + + pr_debug("cpufreq: setting regulator to %d-%d\n", + dvfs->vddarm_min, dvfs->vddarm_max); + ret = regulator_set_voltage(s3c_freq->vddarm, + dvfs->vddarm_min, + dvfs->vddarm_max); + + /* when lowering the voltage failed, there is nothing to do */ + if (ret != 0) + pr_err("cpufreq: Failed to set VDDARM: %d\n", ret); + } +#endif + + s3c_freq->is_dvs = 1; + + return 0; +} + +static int s3c2416_cpufreq_leave_dvs(struct s3c2416_data *s3c_freq, int idx) +{ +#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE + struct s3c2416_dvfs *dvfs; +#endif + int ret; + + if (!s3c_freq->is_dvs) { + pr_debug("cpufreq: not in dvs mode, so can't leave\n"); + return 0; + } + +#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE + if (s3c_freq->vddarm) { + dvfs = &s3c2416_dvfs_table[idx]; + + pr_debug("cpufreq: setting regulator to %d-%d\n", + dvfs->vddarm_min, dvfs->vddarm_max); + ret = regulator_set_voltage(s3c_freq->vddarm, + dvfs->vddarm_min, + dvfs->vddarm_max); + if (ret != 0) { + pr_err("cpufreq: Failed to set VDDARM: %d\n", ret); + return ret; + } + } +#endif + + /* force armdiv to hclk frequency for transition from dvs*/ + if (clk_get_rate(s3c_freq->armdiv) > clk_get_rate(s3c_freq->hclk)) { + pr_debug("cpufreq: force armdiv to hclk frequency (%lukHz)\n", + clk_get_rate(s3c_freq->hclk) / 1000); + ret = s3c2416_cpufreq_set_armdiv(s3c_freq, + clk_get_rate(s3c_freq->hclk) / 1000); + if (ret < 0) { + pr_err("cpufreq: Failed to set the armdiv to %lukHz: %d\n", + clk_get_rate(s3c_freq->hclk) / 1000, ret); + return ret; + } + } + + pr_debug("cpufreq: switching armclk parent to armdiv (%lukHz)\n", + clk_get_rate(s3c_freq->armdiv) / 1000); + + ret = clk_set_parent(s3c_freq->armclk, s3c_freq->armdiv); + if (ret < 0) { + pr_err("cpufreq: Failed to switch armclk clock parent to armdiv: %d\n", + ret); + return ret; + } + + s3c_freq->is_dvs = 0; + + return 0; +} + +static int s3c2416_cpufreq_set_target(struct cpufreq_policy *policy, + unsigned int index) +{ + struct s3c2416_data *s3c_freq = &s3c2416_cpufreq; + unsigned int new_freq; + int idx, ret, to_dvs = 0; + + mutex_lock(&cpufreq_lock); + + idx = s3c_freq->freq_table[index].driver_data; + + if (idx == SOURCE_HCLK) + to_dvs = 1; + + /* switching to dvs when it's not allowed */ + if (to_dvs && s3c_freq->disable_dvs) { + pr_debug("cpufreq: entering dvs mode not allowed\n"); + ret = -EINVAL; + goto out; + } + + /* When leavin dvs mode, always switch the armdiv to the hclk rate + * The S3C2416 has stability issues when switching directly to + * higher frequencies. + */ + new_freq = (s3c_freq->is_dvs && !to_dvs) + ? clk_get_rate(s3c_freq->hclk) / 1000 + : s3c_freq->freq_table[index].frequency; + + if (to_dvs) { + pr_debug("cpufreq: enter dvs\n"); + ret = s3c2416_cpufreq_enter_dvs(s3c_freq, idx); + } else if (s3c_freq->is_dvs) { + pr_debug("cpufreq: leave dvs\n"); + ret = s3c2416_cpufreq_leave_dvs(s3c_freq, idx); + } else { + pr_debug("cpufreq: change armdiv to %dkHz\n", new_freq); + ret = s3c2416_cpufreq_set_armdiv(s3c_freq, new_freq); + } + +out: + mutex_unlock(&cpufreq_lock); + + return ret; +} + +#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE +static void s3c2416_cpufreq_cfg_regulator(struct s3c2416_data *s3c_freq) +{ + int count, v, i, found; + struct cpufreq_frequency_table *pos; + struct s3c2416_dvfs *dvfs; + + count = regulator_count_voltages(s3c_freq->vddarm); + if (count < 0) { + pr_err("cpufreq: Unable to check supported voltages\n"); + return; + } + + if (!count) + goto out; + + cpufreq_for_each_valid_entry(pos, s3c_freq->freq_table) { + dvfs = &s3c2416_dvfs_table[pos->driver_data]; + found = 0; + + /* Check only the min-voltage, more is always ok on S3C2416 */ + for (i = 0; i < count; i++) { + v = regulator_list_voltage(s3c_freq->vddarm, i); + if (v >= dvfs->vddarm_min) + found = 1; + } + + if (!found) { + pr_debug("cpufreq: %dkHz unsupported by regulator\n", + pos->frequency); + pos->frequency = CPUFREQ_ENTRY_INVALID; + } + } + +out: + /* Guessed */ + s3c_freq->regulator_latency = 1 * 1000 * 1000; +} +#endif + +static int s3c2416_cpufreq_reboot_notifier_evt(struct notifier_block *this, + unsigned long event, void *ptr) +{ + struct s3c2416_data *s3c_freq = &s3c2416_cpufreq; + int ret; + struct cpufreq_policy *policy; + + mutex_lock(&cpufreq_lock); + + /* disable further changes */ + s3c_freq->disable_dvs = 1; + + mutex_unlock(&cpufreq_lock); + + /* some boards don't reconfigure the regulator on reboot, which + * could lead to undervolting the cpu when the clock is reset. + * Therefore we always leave the DVS mode on reboot. + */ + if (s3c_freq->is_dvs) { + pr_debug("cpufreq: leave dvs on reboot\n"); + + policy = cpufreq_cpu_get(0); + if (!policy) { + pr_debug("cpufreq: get no policy for cpu0\n"); + return NOTIFY_BAD; + } + + ret = cpufreq_driver_target(policy, FREQ_SLEEP, 0); + cpufreq_cpu_put(policy); + + if (ret < 0) + return NOTIFY_BAD; + } + + return NOTIFY_DONE; +} + +static struct notifier_block s3c2416_cpufreq_reboot_notifier = { + .notifier_call = s3c2416_cpufreq_reboot_notifier_evt, +}; + +static int s3c2416_cpufreq_driver_init(struct cpufreq_policy *policy) +{ + struct s3c2416_data *s3c_freq = &s3c2416_cpufreq; + struct cpufreq_frequency_table *pos; + struct clk *msysclk; + unsigned long rate; + int ret; + + if (policy->cpu != 0) + return -EINVAL; + + msysclk = clk_get(NULL, "msysclk"); + if (IS_ERR(msysclk)) { + ret = PTR_ERR(msysclk); + pr_err("cpufreq: Unable to obtain msysclk: %d\n", ret); + return ret; + } + + /* + * S3C2416 and S3C2450 share the same processor-ID and also provide no + * other means to distinguish them other than through the rate of + * msysclk. On S3C2416 msysclk runs at 800MHz and on S3C2450 at 533MHz. + */ + rate = clk_get_rate(msysclk); + if (rate == 800 * 1000 * 1000) { + pr_info("cpufreq: msysclk running at %lukHz, using S3C2416 frequency table\n", + rate / 1000); + s3c_freq->freq_table = s3c2416_freq_table; + policy->cpuinfo.max_freq = 400000; + } else if (rate / 1000 == 534000) { + pr_info("cpufreq: msysclk running at %lukHz, using S3C2450 frequency table\n", + rate / 1000); + s3c_freq->freq_table = s3c2450_freq_table; + policy->cpuinfo.max_freq = 534000; + } + + /* not needed anymore */ + clk_put(msysclk); + + if (s3c_freq->freq_table == NULL) { + pr_err("cpufreq: No frequency information for this CPU, msysclk at %lukHz\n", + rate / 1000); + return -ENODEV; + } + + s3c_freq->is_dvs = 0; + + s3c_freq->armdiv = clk_get(NULL, "armdiv"); + if (IS_ERR(s3c_freq->armdiv)) { + ret = PTR_ERR(s3c_freq->armdiv); + pr_err("cpufreq: Unable to obtain ARMDIV: %d\n", ret); + return ret; + } + + s3c_freq->hclk = clk_get(NULL, "hclk"); + if (IS_ERR(s3c_freq->hclk)) { + ret = PTR_ERR(s3c_freq->hclk); + pr_err("cpufreq: Unable to obtain HCLK: %d\n", ret); + goto err_hclk; + } + + /* chech hclk rate, we only support the common 133MHz for now + * hclk could also run at 66MHz, but this not often used + */ + rate = clk_get_rate(s3c_freq->hclk); + if (rate < 133 * 1000 * 1000) { + pr_err("cpufreq: HCLK not at 133MHz\n"); + ret = -EINVAL; + goto err_armclk; + } + + s3c_freq->armclk = clk_get(NULL, "armclk"); + if (IS_ERR(s3c_freq->armclk)) { + ret = PTR_ERR(s3c_freq->armclk); + pr_err("cpufreq: Unable to obtain ARMCLK: %d\n", ret); + goto err_armclk; + } + +#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE + s3c_freq->vddarm = regulator_get(NULL, "vddarm"); + if (IS_ERR(s3c_freq->vddarm)) { + ret = PTR_ERR(s3c_freq->vddarm); + pr_err("cpufreq: Failed to obtain VDDARM: %d\n", ret); + goto err_vddarm; + } + + s3c2416_cpufreq_cfg_regulator(s3c_freq); +#else + s3c_freq->regulator_latency = 0; +#endif + + cpufreq_for_each_entry(pos, s3c_freq->freq_table) { + /* special handling for dvs mode */ + if (pos->driver_data == 0) { + if (!s3c_freq->hclk) { + pr_debug("cpufreq: %dkHz unsupported as it would need unavailable dvs mode\n", + pos->frequency); + pos->frequency = CPUFREQ_ENTRY_INVALID; + } else { + continue; + } + } + + /* Check for frequencies we can generate */ + rate = clk_round_rate(s3c_freq->armdiv, + pos->frequency * 1000); + rate /= 1000; + if (rate != pos->frequency) { + pr_debug("cpufreq: %dkHz unsupported by clock (clk_round_rate return %lu)\n", + pos->frequency, rate); + pos->frequency = CPUFREQ_ENTRY_INVALID; + } + } + + /* Datasheet says PLL stabalisation time must be at least 300us, + * so but add some fudge. (reference in LOCKCON0 register description) + */ + cpufreq_generic_init(policy, s3c_freq->freq_table, + (500 * 1000) + s3c_freq->regulator_latency); + register_reboot_notifier(&s3c2416_cpufreq_reboot_notifier); + + return 0; + +#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE +err_vddarm: + clk_put(s3c_freq->armclk); +#endif +err_armclk: + clk_put(s3c_freq->hclk); +err_hclk: + clk_put(s3c_freq->armdiv); + + return ret; +} + +static struct cpufreq_driver s3c2416_cpufreq_driver = { + .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK, + .verify = cpufreq_generic_frequency_table_verify, + .target_index = s3c2416_cpufreq_set_target, + .get = s3c2416_cpufreq_get_speed, + .init = s3c2416_cpufreq_driver_init, + .name = "s3c2416", + .attr = cpufreq_generic_attr, +}; + +static int __init s3c2416_cpufreq_init(void) +{ + return cpufreq_register_driver(&s3c2416_cpufreq_driver); +} +module_init(s3c2416_cpufreq_init); |