linux/drivers/cpufreq/tegra194-cpufreq.c
Jon Hunter f45f89a778 cpufreq: tegra194: Rename tegra194_get_speed_common function
The function tegra194_get_speed_common() uses hardware timers to
calculate the current CPUFREQ and so rename this function to be
tegra194_calculate_speed() to reflect what it does.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
2020-12-07 13:02:44 +05:30

433 lines
11 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved
*/
#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>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <asm/smp_plat.h>
#include <soc/tegra/bpmp.h>
#include <soc/tegra/bpmp-abi.h>
#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
/* cpufreq transisition latency */
#define TEGRA_CPUFREQ_TRANSITION_LATENCY (300 * 1000) /* unit in nanoseconds */
enum cluster {
CLUSTER0,
CLUSTER1,
CLUSTER2,
CLUSTER3,
MAX_CLUSTERS,
};
struct tegra194_cpufreq_data {
void __iomem *regs;
size_t num_clusters;
struct cpufreq_frequency_table **tables;
};
struct tegra_cpu_ctr {
u32 cpu;
u32 coreclk_cnt, last_coreclk_cnt;
u32 refclk_cnt, last_refclk_cnt;
};
struct read_counters_work {
struct work_struct work;
struct tegra_cpu_ctr c;
};
static struct workqueue_struct *read_counters_wq;
static void get_cpu_cluster(void *cluster)
{
u64 mpidr = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;
*((uint32_t *)cluster) = MPIDR_AFFINITY_LEVEL(mpidr, 1);
}
/*
* Read per-core Read-only system register NVFREQ_FEEDBACK_EL1.
* The register provides frequency feedback information to
* determine the average actual frequency a core has run at over
* a period of time.
* [31:0] PLLP counter: Counts at fixed frequency (408 MHz)
* [63:32] Core clock counter: counts on every core clock cycle
* where the core is architecturally clocking
*/
static u64 read_freq_feedback(void)
{
u64 val = 0;
asm volatile("mrs %0, s3_0_c15_c0_5" : "=r" (val) : );
return val;
}
static inline u32 map_ndiv_to_freq(struct mrq_cpu_ndiv_limits_response
*nltbl, u16 ndiv)
{
return nltbl->ref_clk_hz / KHZ * ndiv / (nltbl->pdiv * nltbl->mdiv);
}
static void tegra_read_counters(struct work_struct *work)
{
struct read_counters_work *read_counters_work;
struct tegra_cpu_ctr *c;
u64 val;
/*
* ref_clk_counter(32 bit counter) runs on constant clk,
* pll_p(408MHz).
* It will take = 2 ^ 32 / 408 MHz to overflow ref clk counter
* = 10526880 usec = 10.527 sec to overflow
*
* Like wise core_clk_counter(32 bit counter) runs on core clock.
* It's synchronized to crab_clk (cpu_crab_clk) which runs at
* freq of cluster. Assuming max cluster clock ~2000MHz,
* It will take = 2 ^ 32 / 2000 MHz to overflow core clk counter
* = ~2.147 sec to overflow
*/
read_counters_work = container_of(work, struct read_counters_work,
work);
c = &read_counters_work->c;
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);
}
/*
* Return instantaneous cpu speed
* Instantaneous freq is calculated as -
* -Takes sample on every query of getting the freq.
* - Read core and ref clock counters;
* - Delay for X us
* - Read above cycle counters again
* - Calculates freq by subtracting current and previous counters
* divided by the delay time or eqv. of ref_clk_counter in delta time
* - Return Kcycles/second, freq in KHz
*
* delta time period = x sec
* = delta ref_clk_counter / (408 * 10^6) sec
* freq in Hz = cycles/sec
* = (delta cycles / x sec
* = (delta cycles * 408 * 10^6) / delta ref_clk_counter
* in KHz = (delta cycles * 408 * 10^3) / delta ref_clk_counter
*
* @cpu - logical cpu whose freq to be updated
* Returns freq in KHz on success, 0 if cpu is offline
*/
static unsigned int tegra194_calculate_speed(u32 cpu)
{
struct read_counters_work read_counters_work;
struct tegra_cpu_ctr c;
u32 delta_refcnt;
u32 delta_ccnt;
u32 rate_mhz;
/*
* udelay() is required to reconstruct cpu frequency over an
* observation window. Using workqueue to call udelay() with
* interrupts enabled.
*/
read_counters_work.c.cpu = cpu;
INIT_WORK_ONSTACK(&read_counters_work.work, tegra_read_counters);
queue_work_on(cpu, read_counters_wq, &read_counters_work.work);
flush_work(&read_counters_work.work);
c = read_counters_work.c;
if (c.coreclk_cnt < c.last_coreclk_cnt)
delta_ccnt = c.coreclk_cnt + (MAX_CNT - c.last_coreclk_cnt);
else
delta_ccnt = c.coreclk_cnt - c.last_coreclk_cnt;
if (!delta_ccnt)
return 0;
/* ref clock is 32 bits */
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 (!delta_refcnt) {
pr_debug("cpufreq: %d is idle, delta_refcnt: 0\n", cpu);
return 0;
}
rate_mhz = ((unsigned long)(delta_ccnt * REF_CLK_MHZ)) / delta_refcnt;
return (rate_mhz * KHZ); /* in KHz */
}
static void get_cpu_ndiv(void *ndiv)
{
u64 ndiv_val;
asm volatile("mrs %0, s3_0_c15_c0_4" : "=r" (ndiv_val) : );
*(u64 *)ndiv = ndiv_val;
}
static void set_cpu_ndiv(void *data)
{
struct cpufreq_frequency_table *tbl = data;
u64 ndiv_val = (u64)tbl->driver_data;
asm volatile("msr s3_0_c15_c0_4, %0" : : "r" (ndiv_val));
}
static unsigned int tegra194_get_speed(u32 cpu)
{
struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
struct cpufreq_frequency_table *pos;
unsigned int rate;
u64 ndiv;
int ret;
u32 cl;
smp_call_function_single(cpu, get_cpu_cluster, &cl, true);
/* reconstruct actual cpu freq using counters */
rate = tegra194_calculate_speed(cpu);
/* get last written ndiv value */
ret = smp_call_function_single(cpu, get_cpu_ndiv, &ndiv, true);
if (WARN_ON_ONCE(ret))
return rate;
/*
* If the reconstructed frequency has acceptable delta from
* the last written value, then return freq corresponding
* to the last written ndiv value from freq_table. This is
* done to return consistent value.
*/
cpufreq_for_each_valid_entry(pos, data->tables[cl]) {
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);
} else {
rate = pos->frequency;
}
break;
}
return rate;
}
static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
{
struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
u32 cpu;
u32 cl;
smp_call_function_single(policy->cpu, get_cpu_cluster, &cl, true);
if (cl >= data->num_clusters)
return -EINVAL;
/* set same policy for all cpus in a cluster */
for (cpu = (cl * 2); cpu < ((cl + 1) * 2); cpu++)
cpumask_set_cpu(cpu, policy->cpus);
policy->freq_table = data->tables[cl];
policy->cpuinfo.transition_latency = TEGRA_CPUFREQ_TRANSITION_LATENCY;
return 0;
}
static int tegra194_cpufreq_set_target(struct cpufreq_policy *policy,
unsigned int index)
{
struct cpufreq_frequency_table *tbl = policy->freq_table + index;
/*
* Each core writes frequency in per core register. Then both cores
* in a cluster run at same frequency which is the maximum frequency
* request out of the values requested by both cores in that cluster.
*/
on_each_cpu_mask(policy->cpus, set_cpu_ndiv, tbl, true);
return 0;
}
static struct cpufreq_driver tegra194_cpufreq_driver = {
.name = "tegra194",
.flags = CPUFREQ_STICKY | CPUFREQ_CONST_LOOPS |
CPUFREQ_NEED_INITIAL_FREQ_CHECK,
.verify = cpufreq_generic_frequency_table_verify,
.target_index = tegra194_cpufreq_set_target,
.get = tegra194_get_speed,
.init = tegra194_cpufreq_init,
.attr = cpufreq_generic_attr,
};
static void tegra194_cpufreq_free_resources(void)
{
destroy_workqueue(read_counters_wq);
}
static struct cpufreq_frequency_table *
init_freq_table(struct platform_device *pdev, struct tegra_bpmp *bpmp,
unsigned int cluster_id)
{
struct cpufreq_frequency_table *freq_table;
struct mrq_cpu_ndiv_limits_response resp;
unsigned int num_freqs, ndiv, delta_ndiv;
struct mrq_cpu_ndiv_limits_request req;
struct tegra_bpmp_message msg;
u16 freq_table_step_size;
int err, index;
memset(&req, 0, sizeof(req));
req.cluster_id = cluster_id;
memset(&msg, 0, sizeof(msg));
msg.mrq = MRQ_CPU_NDIV_LIMITS;
msg.tx.data = &req;
msg.tx.size = sizeof(req);
msg.rx.data = &resp;
msg.rx.size = sizeof(resp);
err = tegra_bpmp_transfer(bpmp, &msg);
if (err)
return ERR_PTR(err);
/*
* Make sure frequency table step is a multiple of mdiv to match
* vhint table granularity.
*/
freq_table_step_size = resp.mdiv *
DIV_ROUND_UP(CPUFREQ_TBL_STEP_HZ, resp.ref_clk_hz);
dev_dbg(&pdev->dev, "cluster %d: frequency table step size: %d\n",
cluster_id, freq_table_step_size);
delta_ndiv = resp.ndiv_max - resp.ndiv_min;
if (unlikely(delta_ndiv == 0)) {
num_freqs = 1;
} else {
/* We store both ndiv_min and ndiv_max hence the +1 */
num_freqs = delta_ndiv / freq_table_step_size + 1;
}
num_freqs += (delta_ndiv % freq_table_step_size) ? 1 : 0;
freq_table = devm_kcalloc(&pdev->dev, num_freqs + 1,
sizeof(*freq_table), GFP_KERNEL);
if (!freq_table)
return ERR_PTR(-ENOMEM);
for (index = 0, ndiv = resp.ndiv_min;
ndiv < resp.ndiv_max;
index++, ndiv += freq_table_step_size) {
freq_table[index].driver_data = ndiv;
freq_table[index].frequency = map_ndiv_to_freq(&resp, ndiv);
}
freq_table[index].driver_data = resp.ndiv_max;
freq_table[index++].frequency = map_ndiv_to_freq(&resp, resp.ndiv_max);
freq_table[index].frequency = CPUFREQ_TABLE_END;
return freq_table;
}
static int tegra194_cpufreq_probe(struct platform_device *pdev)
{
struct tegra194_cpufreq_data *data;
struct tegra_bpmp *bpmp;
int err, i;
data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
data->num_clusters = MAX_CLUSTERS;
data->tables = devm_kcalloc(&pdev->dev, data->num_clusters,
sizeof(*data->tables), GFP_KERNEL);
if (!data->tables)
return -ENOMEM;
platform_set_drvdata(pdev, data);
bpmp = tegra_bpmp_get(&pdev->dev);
if (IS_ERR(bpmp))
return PTR_ERR(bpmp);
read_counters_wq = alloc_workqueue("read_counters_wq", __WQ_LEGACY, 1);
if (!read_counters_wq) {
dev_err(&pdev->dev, "fail to create_workqueue\n");
err = -EINVAL;
goto put_bpmp;
}
for (i = 0; i < data->num_clusters; i++) {
data->tables[i] = init_freq_table(pdev, bpmp, i);
if (IS_ERR(data->tables[i])) {
err = PTR_ERR(data->tables[i]);
goto err_free_res;
}
}
tegra194_cpufreq_driver.driver_data = data;
err = cpufreq_register_driver(&tegra194_cpufreq_driver);
if (!err)
goto put_bpmp;
err_free_res:
tegra194_cpufreq_free_resources();
put_bpmp:
tegra_bpmp_put(bpmp);
return err;
}
static int tegra194_cpufreq_remove(struct platform_device *pdev)
{
cpufreq_unregister_driver(&tegra194_cpufreq_driver);
tegra194_cpufreq_free_resources();
return 0;
}
static const struct of_device_id tegra194_cpufreq_of_match[] = {
{ .compatible = "nvidia,tegra194-ccplex", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, tegra194_cpufreq_of_match);
static struct platform_driver tegra194_ccplex_driver = {
.driver = {
.name = "tegra194-cpufreq",
.of_match_table = tegra194_cpufreq_of_match,
},
.probe = tegra194_cpufreq_probe,
.remove = tegra194_cpufreq_remove,
};
module_platform_driver(tegra194_ccplex_driver);
MODULE_AUTHOR("Mikko Perttunen <mperttunen@nvidia.com>");
MODULE_AUTHOR("Sumit Gupta <sumitg@nvidia.com>");
MODULE_DESCRIPTION("NVIDIA Tegra194 cpufreq driver");
MODULE_LICENSE("GPL v2");