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Message-ID: <97b9cde0-b33e-503e-ad29-e3c85adc26c4@codeaurora.org>
Date: Sun, 23 Sep 2018 15:18:20 +0530
From: Taniya Das <tdas@...eaurora.org>
To: Matthias Kaehlcke <mka@...omium.org>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>,
Viresh Kumar <viresh.kumar@...aro.org>,
linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
Stephen Boyd <sboyd@...nel.org>,
Rajendra Nayak <rnayak@...eaurora.org>,
Amit Nischal <anischal@...eaurora.org>,
devicetree@...r.kernel.org, robh@...nel.org,
skannan@...eaurora.org, amit.kucheria@...aro.org,
evgreen@...gle.com
Subject: Re: [PATCH v7 2/2] cpufreq: qcom-hw: Add support for QCOM cpufreq HW
driver
On 9/11/2018 1:00 AM, Matthias Kaehlcke wrote:
> On Tue, Jul 24, 2018 at 04:12:50PM +0530, Taniya Das wrote:
>> The CPUfreq HW present in some QCOM chipsets offloads the steps necessary
>> for changing the frequency of CPUs. The driver implements the cpufreq
>> driver interface for this hardware engine.
>>
>> Signed-off-by: Saravana Kannan <skannan@...eaurora.org>
>> Signed-off-by: Taniya Das <tdas@...eaurora.org>
>> ---
>> drivers/cpufreq/Kconfig.arm | 11 ++
>> drivers/cpufreq/Makefile | 1 +
>> drivers/cpufreq/qcom-cpufreq-hw.c | 348 ++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 360 insertions(+)
>> create mode 100644 drivers/cpufreq/qcom-cpufreq-hw.c
>>
>> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
>> index 0cd8eb7..93a9d72 100644
>> --- a/drivers/cpufreq/Kconfig.arm
>> +++ b/drivers/cpufreq/Kconfig.arm
>> @@ -298,3 +298,14 @@ config ARM_PXA2xx_CPUFREQ
>> This add the CPUFreq driver support for Intel PXA2xx SOCs.
>>
>> If in doubt, say N.
>> +
>> +config ARM_QCOM_CPUFREQ_HW
>> + bool "QCOM CPUFreq HW driver"
>> + depends on ARCH_QCOM
>> + help
>> + Support for the CPUFreq HW driver.
>> + Some QCOM chipsets have a HW engine to offload the steps
>> + necessary for changing the frequency of the CPUs. Firmware loaded
>> + in this engine exposes a programming interface to the OS.
>> + The driver implements the cpufreq interface for this HW engine.
>> + Say Y if you want to support CPUFreq HW.
>> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
>> index c1ffeab..ca48a1d 100644
>> --- a/drivers/cpufreq/Makefile
>> +++ b/drivers/cpufreq/Makefile
>> @@ -85,6 +85,7 @@ obj-$(CONFIG_ARM_TEGRA124_CPUFREQ) += tegra124-cpufreq.o
>> obj-$(CONFIG_ARM_TEGRA186_CPUFREQ) += tegra186-cpufreq.o
>> obj-$(CONFIG_ARM_TI_CPUFREQ) += ti-cpufreq.o
>> obj-$(CONFIG_ARM_VEXPRESS_SPC_CPUFREQ) += vexpress-spc-cpufreq.o
>> +obj-$(CONFIG_ARM_QCOM_CPUFREQ_HW) += qcom-cpufreq-hw.o
>>
>>
>> ##################################################################################
>> diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
>> new file mode 100644
>> index 0000000..ea8f7d1
>> --- /dev/null
>> +++ b/drivers/cpufreq/qcom-cpufreq-hw.c
>> @@ -0,0 +1,348 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (c) 2018, The Linux Foundation. All rights reserved.
>> + */
>> +
>> +#include <linux/cpufreq.h>
>> +#include <linux/init.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/of_address.h>
>> +#include <linux/of_platform.h>
>> +
>> +#define INIT_RATE 300000000UL
>> +#define LUT_MAX_ENTRIES 40U
>> +#define CORE_COUNT_VAL(val) (((val) & (GENMASK(18, 16))) >> 16)
>> +#define LUT_ROW_SIZE 32
>> +
>> +enum {
>> + REG_ENABLE,
>> + REG_LUT_TABLE,
>> + REG_PERF_STATE,
>> +
>> + REG_ARRAY_SIZE,
>> +};
>> +
>> +struct cpufreq_qcom {
>> + struct cpufreq_frequency_table *table;
>> + struct device *dev;
>> + void __iomem *reg_bases[REG_ARRAY_SIZE];
>> + cpumask_t related_cpus;
>> + unsigned int max_cores;
>> + unsigned long xo_rate;
>> +};
>> +
>> +static const u16 cpufreq_qcom_std_offsets[REG_ARRAY_SIZE] = {
>> + [REG_ENABLE] = 0x0,
>> + [REG_LUT_TABLE] = 0x110,
>> + [REG_PERF_STATE] = 0x920,
>> +};
>> +
>> +static struct cpufreq_qcom *qcom_freq_domain_map[NR_CPUS];
>> +
>> +static int
>> +qcom_cpufreq_hw_target_index(struct cpufreq_policy *policy,
>> + unsigned int index)
>> +{
>> + struct cpufreq_qcom *c = policy->driver_data;
>> +
>> + writel_relaxed(index, c->reg_bases[REG_PERF_STATE]);
>> +
>> + return 0;
>> +}
>> +
>> +static unsigned int qcom_cpufreq_hw_get(unsigned int cpu)
>> +{
>> + struct cpufreq_qcom *c;
>> + struct cpufreq_policy *policy;
>> + unsigned int index;
>> +
>> + policy = cpufreq_cpu_get_raw(cpu);
>> + if (!policy)
>> + return 0;
>> +
>> + c = policy->driver_data;
>> +
>> + index = readl_relaxed(c->reg_bases[REG_PERF_STATE]);
>> + index = min(index, LUT_MAX_ENTRIES - 1);
>> +
>> + return policy->freq_table[index].frequency;
>> +}
>> +
>> +static unsigned int
>> +qcom_cpufreq_hw_fast_switch(struct cpufreq_policy *policy,
>> + unsigned int target_freq)
>> +{
>> + struct cpufreq_qcom *c = policy->driver_data;
>> + int index;
>> +
>> + index = policy->cached_resolved_idx;
>> + if (index < 0)
>> + return 0;
>> +
>> + writel_relaxed(index, c->reg_bases[REG_PERF_STATE]);
>> +
>> + return policy->freq_table[index].frequency;
>> +}
>> +
>> +static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
>> +{
>> + struct cpufreq_qcom *c;
>> +
>> + c = qcom_freq_domain_map[policy->cpu];
>> + if (!c) {
>> + pr_err("No scaling support for CPU%d\n", policy->cpu);
>> + return -ENODEV;
>> + }
>> +
>> + cpumask_copy(policy->cpus, &c->related_cpus);
>> +
>> + policy->fast_switch_possible = true;
>> + policy->freq_table = c->table;
>> + policy->driver_data = c;
>> +
>> + return 0;
>> +}
>> +
>> +static struct freq_attr *qcom_cpufreq_hw_attr[] = {
>> + &cpufreq_freq_attr_scaling_available_freqs,
>> + &cpufreq_freq_attr_scaling_boost_freqs,
>> + NULL
>> +};
>> +
>> +static struct cpufreq_driver cpufreq_qcom_hw_driver = {
>> + .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK |
>> + CPUFREQ_HAVE_GOVERNOR_PER_POLICY,
>> + .verify = cpufreq_generic_frequency_table_verify,
>> + .target_index = qcom_cpufreq_hw_target_index,
>> + .get = qcom_cpufreq_hw_get,
>> + .init = qcom_cpufreq_hw_cpu_init,
>> + .fast_switch = qcom_cpufreq_hw_fast_switch,
>> + .name = "qcom-cpufreq-hw",
>> + .attr = qcom_cpufreq_hw_attr,
>> + .boost_enabled = true,
>> +};
>> +
>> +static int qcom_cpufreq_hw_read_lut(struct platform_device *pdev,
>> + struct cpufreq_qcom *c)
>> +{
>> + struct device *dev = &pdev->dev;
>> + void __iomem *base;
>> + u32 data, src, lval, i, core_count, prev_cc, prev_freq, cur_freq;
>> +
>> + c->table = devm_kcalloc(dev, LUT_MAX_ENTRIES + 1,
>> + sizeof(*c->table), GFP_KERNEL);
>> + if (!c->table)
>> + return -ENOMEM;
>> +
>> + base = c->reg_bases[REG_LUT_TABLE];
>> +
>> + for (i = 0; i < LUT_MAX_ENTRIES; i++) {
>> + data = readl_relaxed(base + i * LUT_ROW_SIZE);
>> + src = (data & GENMASK(31, 30)) >> 30;
>> + lval = data & GENMASK(7, 0);
>> + core_count = CORE_COUNT_VAL(data);
>> +
>> + if (src)
>> + c->table[i].frequency = c->xo_rate * lval / 1000;
>> + else
>> + c->table[i].frequency = INIT_RATE / 1000;
>> +
>> + cur_freq = c->table[i].frequency;
>> +
>> + dev_dbg(dev, "index=%d freq=%d, core_count %d\n",
>> + i, c->table[i].frequency, core_count);
>> +
>> + if (core_count != c->max_cores)
>> + cur_freq = CPUFREQ_ENTRY_INVALID;
>> +
>
> I noticed that the 'power_allocator' thermal governor currently can't
> be used with this driver since there is no OPP table with frequency and
> voltage information. Does the LUT contain information about the
> voltage or is there another mechanism to retrieve it?
>
No, currently there is no way of reading the voltage information.
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