diff options
Diffstat (limited to 'drivers/cpufreq/tegra194-cpufreq.c')
| -rw-r--r-- | drivers/cpufreq/tegra194-cpufreq.c | 394 |
1 files changed, 394 insertions, 0 deletions
diff --git a/drivers/cpufreq/tegra194-cpufreq.c b/drivers/cpufreq/tegra194-cpufreq.c new file mode 100644 index 000000000..e1d931c45 --- /dev/null +++ b/drivers/cpufreq/tegra194-cpufreq.c @@ -0,0 +1,394 @@ +// 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 US_DELAY_MIN 2 +#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 delay; + 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(c->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_get_speed_common(u32 cpu, u32 delay) +{ + 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; + read_counters_work.c.delay = delay; + 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 unsigned int tegra194_get_speed(u32 cpu) +{ + return tegra194_get_speed_common(cpu, US_DELAY); +} + +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; + + /* boot freq */ + policy->cur = tegra194_get_speed_common(policy->cpu, US_DELAY_MIN); + + /* 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 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 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"); |