diff options
Diffstat (limited to 'drivers/cpufreq/tegra194-cpufreq.c')
| -rw-r--r-- | drivers/cpufreq/tegra194-cpufreq.c | 72 |
1 files changed, 55 insertions, 17 deletions
diff --git a/drivers/cpufreq/tegra194-cpufreq.c b/drivers/cpufreq/tegra194-cpufreq.c index f6a8e6cf6d94..9dae6195e0e7 100644 --- a/drivers/cpufreq/tegra194-cpufreq.c +++ b/drivers/cpufreq/tegra194-cpufreq.c @@ -5,7 +5,6 @@ #include <linux/cpu.h> #include <linux/cpufreq.h> -#include <linux/delay.h> #include <linux/dma-mapping.h> #include <linux/module.h> #include <linux/of.h> @@ -21,10 +20,11 @@ #define KHZ 1000 #define REF_CLK_MHZ 408 /* 408 MHz */ -#define US_DELAY 500 #define CPUFREQ_TBL_STEP_HZ (50 * KHZ * KHZ) #define MAX_CNT ~0U +#define MAX_DELTA_KHZ 115200 + #define NDIV_MASK 0x1FF #define CORE_OFFSET(cpu) (cpu * 8) @@ -68,6 +68,7 @@ struct tegra_cpufreq_soc { int maxcpus_per_cluster; unsigned int num_clusters; phys_addr_t actmon_cntr_base; + u32 refclk_delta_min; }; struct tegra194_cpufreq_data { @@ -149,6 +150,8 @@ static void tegra234_read_counters(struct tegra_cpu_ctr *c) { struct tegra194_cpufreq_data *data = cpufreq_get_driver_data(); void __iomem *actmon_reg; + u32 delta_refcnt; + int cnt = 0; u64 val; actmon_reg = CORE_ACTMON_CNTR_REG(data, data->cpu_data[c->cpu].clusterid, @@ -157,10 +160,25 @@ static void tegra234_read_counters(struct tegra_cpu_ctr *c) val = readq(actmon_reg); c->last_refclk_cnt = upper_32_bits(val); c->last_coreclk_cnt = lower_32_bits(val); - udelay(US_DELAY); - val = readq(actmon_reg); - c->refclk_cnt = upper_32_bits(val); - c->coreclk_cnt = lower_32_bits(val); + + /* + * The sampling window is based on the minimum number of reference + * clock cycles which is known to give a stable value of CPU frequency. + */ + do { + val = readq(actmon_reg); + c->refclk_cnt = upper_32_bits(val); + c->coreclk_cnt = lower_32_bits(val); + if (c->refclk_cnt < c->last_refclk_cnt) + delta_refcnt = c->refclk_cnt + (MAX_CNT - c->last_refclk_cnt); + else + delta_refcnt = c->refclk_cnt - c->last_refclk_cnt; + if (++cnt >= 0xFFFF) { + pr_warn("cpufreq: problem with refclk on cpu:%d, delta_refcnt:%u, cnt:%d\n", + c->cpu, delta_refcnt, cnt); + break; + } + } while (delta_refcnt < data->soc->refclk_delta_min); } static struct tegra_cpufreq_ops tegra234_cpufreq_ops = { @@ -175,6 +193,7 @@ static const struct tegra_cpufreq_soc tegra234_cpufreq_soc = { .actmon_cntr_base = 0x9000, .maxcpus_per_cluster = 4, .num_clusters = 3, + .refclk_delta_min = 16000, }; static const struct tegra_cpufreq_soc tegra239_cpufreq_soc = { @@ -182,6 +201,7 @@ static const struct tegra_cpufreq_soc tegra239_cpufreq_soc = { .actmon_cntr_base = 0x4000, .maxcpus_per_cluster = 8, .num_clusters = 1, + .refclk_delta_min = 16000, }; static void tegra194_get_cpu_cluster_id(u32 cpu, u32 *cpuid, u32 *clusterid) @@ -222,15 +242,33 @@ static inline u32 map_ndiv_to_freq(struct mrq_cpu_ndiv_limits_response static void tegra194_read_counters(struct tegra_cpu_ctr *c) { + struct tegra194_cpufreq_data *data = cpufreq_get_driver_data(); + u32 delta_refcnt; + int cnt = 0; u64 val; val = read_freq_feedback(); c->last_refclk_cnt = lower_32_bits(val); c->last_coreclk_cnt = upper_32_bits(val); - udelay(US_DELAY); - val = read_freq_feedback(); - c->refclk_cnt = lower_32_bits(val); - c->coreclk_cnt = upper_32_bits(val); + + /* + * The sampling window is based on the minimum number of reference + * clock cycles which is known to give a stable value of CPU frequency. + */ + do { + val = read_freq_feedback(); + c->refclk_cnt = lower_32_bits(val); + c->coreclk_cnt = upper_32_bits(val); + if (c->refclk_cnt < c->last_refclk_cnt) + delta_refcnt = c->refclk_cnt + (MAX_CNT - c->last_refclk_cnt); + else + delta_refcnt = c->refclk_cnt - c->last_refclk_cnt; + if (++cnt >= 0xFFFF) { + pr_warn("cpufreq: problem with refclk on cpu:%d, delta_refcnt:%u, cnt:%d\n", + c->cpu, delta_refcnt, cnt); + break; + } + } while (delta_refcnt < data->soc->refclk_delta_min); } static void tegra_read_counters(struct work_struct *work) @@ -288,9 +326,8 @@ static unsigned int tegra194_calculate_speed(u32 cpu) u32 rate_mhz; /* - * udelay() is required to reconstruct cpu frequency over an - * observation window. Using workqueue to call udelay() with - * interrupts enabled. + * Reconstruct cpu frequency over an observation/sampling window. + * Using workqueue to keep interrupts enabled during the interval. */ read_counters_work.c.cpu = cpu; INIT_WORK_ONSTACK(&read_counters_work.work, tegra_read_counters); @@ -372,9 +409,9 @@ static unsigned int tegra194_get_speed(u32 cpu) if (pos->driver_data != ndiv) continue; - if (abs(pos->frequency - rate) > 115200) { - pr_warn("cpufreq: cpu%d,cur:%u,set:%u,set ndiv:%llu\n", - cpu, rate, pos->frequency, ndiv); + if (abs(pos->frequency - rate) > MAX_DELTA_KHZ) { + pr_warn("cpufreq: cpu%d,cur:%u,set:%u,delta:%d,set ndiv:%llu\n", + cpu, rate, pos->frequency, abs(rate - pos->frequency), ndiv); } else { rate = pos->frequency; } @@ -568,6 +605,7 @@ static const struct tegra_cpufreq_soc tegra194_cpufreq_soc = { .ops = &tegra194_cpufreq_ops, .maxcpus_per_cluster = 2, .num_clusters = 4, + .refclk_delta_min = 16000, }; static void tegra194_cpufreq_free_resources(void) @@ -684,7 +722,7 @@ static int tegra194_cpufreq_probe(struct platform_device *pdev) soc = of_device_get_match_data(&pdev->dev); - if (soc->ops && soc->maxcpus_per_cluster && soc->num_clusters) { + if (soc->ops && soc->maxcpus_per_cluster && soc->num_clusters && soc->refclk_delta_min) { data->soc = soc; } else { dev_err(&pdev->dev, "soc data missing\n"); |