Date:   Thu, 17 May 2018 22:43:52 +0530
From:   Taniya Das <tdas@...eaurora.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        Stephen Boyd <sboyd@...eaurora.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Amit Nischal <anischal@...eaurora.org>,
        devicetree@...r.kernel.org, amit.kucheria@...aro.org
Subject: Re: [v0 2/2] cpufreq: qcom-fw: Add support for QCOM cpufreq FW driver

Hi Viresh,

Thanks for the review comments, I have already fixed the resource 
comment in the v1 series which I sent across. I will fix the rest of the 
comments and send it for review.

On 5/17/2018 3:44 PM, Viresh Kumar wrote:
> On 17-05-18, 15:00, Taniya Das wrote:
>> The CPUfreq FW present in some QCOM chipsets offloads the steps necessary
>> for hanging the frequency of CPUs. The driver implements the cpufreq driver
>> interface for this firmware.
>>
>> Signed-off-by: Taniya Das <tdas@...eaurora.org>
>> ---
>>   drivers/cpufreq/Kconfig.arm       |   9 ++
>>   drivers/cpufreq/Makefile          |   1 +
>>   drivers/cpufreq/qcom-cpufreq-fw.c | 318 ++++++++++++++++++++++++++++++++++++++
>>   3 files changed, 328 insertions(+)
>>   create mode 100644 drivers/cpufreq/qcom-cpufreq-fw.c
>>
>> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
>> index 96b35b8..a50aa6e 100644
>> --- a/drivers/cpufreq/Kconfig.arm
>> +++ b/drivers/cpufreq/Kconfig.arm
>> @@ -301,3 +301,12 @@ config ARM_PXA2xx_CPUFREQ
>>   	  This add the CPUFreq driver support for Intel PXA2xx SOCs.
>>
>>   	  If in doubt, say N.
>> +
>> +config ARM_QCOM_CPUFREQ_FW
>> +	tristate "QCOM CPUFreq FW driver"
>> +	help
>> +	 Support for the CPUFreq FW driver.
>> +	 The CPUfreq FW preset in some QCOM chipsets offloads the steps
>> +	 necessary for changing the frequency of CPUs. The driver
>> +	 implements the cpufreq driver interface for this firmware.
>> +	 Say Y if you want to support CPUFreq FW.
>> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
>> index 8d24ade..a3edbce 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_FW)	+= qcom-cpufreq-fw.o
>>
>>
>>   ##################################################################################
>> diff --git a/drivers/cpufreq/qcom-cpufreq-fw.c b/drivers/cpufreq/qcom-cpufreq-fw.c
>> new file mode 100644
>> index 0000000..67996d5
>> --- /dev/null
>> +++ b/drivers/cpufreq/qcom-cpufreq-fw.c
>> @@ -0,0 +1,318 @@
>> +// 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 XO_RATE				19200000UL
>> +#define LUT_MAX_ENTRIES			40U
>> +#define CORE_COUNT_VAL(val)		((val & GENMASK(18, 16)) >> 16)
>> +#define LUT_ROW_SIZE			32
>> +
>> +struct cpufreq_qcom {
>> +	struct cpufreq_frequency_table *table;
>> +	struct device *dev;
>> +	void __iomem *perf_base;
>> +	void __iomem *lut_base;
>> +	cpumask_t related_cpus;
>> +	unsigned int max_cores;
>> +};
>> +
>> +static struct cpufreq_qcom *qcom_freq_domain_map[NR_CPUS];
>> +
>> +static int
>> +qcom_cpufreq_fw_target_index(struct cpufreq_policy *policy, unsigned int index)
>> +{
>> +	struct cpufreq_qcom *c = policy->driver_data;
>> +
>> +	if (index >= LUT_MAX_ENTRIES) {
>> +		dev_err(c->dev,
>> +		"Passing an index (%u) that's greater than max (%d)\n",
> 
> Alignment issues here. Run checkpatch --strict.
> 
>> +					index, LUT_MAX_ENTRIES - 1);
>> +		return -EINVAL;
>> +	}
>> +
>> +	writel_relaxed(index, c->perf_base);
>> +
>> +	/* Make sure the write goes through before proceeding */
>> +	mb();
>> +	return 0;
>> +}
>> +
>> +static unsigned int qcom_cpufreq_fw_get(unsigned int cpu)
>> +{
>> +	struct cpufreq_qcom *c;
>> +	unsigned int index;
>> +
>> +	c = qcom_freq_domain_map[cpu];
>> +	if (!c)
>> +		return -ENODEV;
>> +
>> +	index = readl_relaxed(c->perf_base);
>> +	index = min(index, LUT_MAX_ENTRIES - 1);
>> +
>> +	return c->table[index].frequency;
>> +}
>> +
>> +static int qcom_cpufreq_fw_cpu_init(struct cpufreq_policy *policy)
>> +{
>> +	struct cpufreq_qcom *c;
>> +	int ret;
>> +
>> +	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->table = c->table;
>> +	policy->driver_data = c;
>> +
>> +	return ret;
>> +}
>> +
>> +static struct freq_attr *qcom_cpufreq_fw_attr[] = {
>> +	&cpufreq_freq_attr_scaling_available_freqs,
>> +	&cpufreq_freq_attr_scaling_boost_freqs,
>> +	NULL
>> +};
>> +
>> +static struct cpufreq_driver cpufreq_qcom_fw_driver = {
>> +	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK |
>> +			  CPUFREQ_HAVE_GOVERNOR_PER_POLICY,
>> +	.verify		= cpufreq_generic_frequency_table_verify,
>> +	.target_index	= qcom_cpufreq_fw_target_index,
>> +	.get		= qcom_cpufreq_fw_get,
>> +	.init		= qcom_cpufreq_fw_cpu_init,
>> +	.name		= "qcom-cpufreq-fw",
>> +	.attr		= qcom_cpufreq_fw_attr,
>> +	.boost_enabled	= true,
>> +};
>> +
>> +static int qcom_read_lut(struct platform_device *pdev,
>> +			struct cpufreq_qcom *c)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	u32 data, src, lval, i, core_count, prev_cc = 0;
>> +
>> +	c->table = devm_kcalloc(dev, LUT_MAX_ENTRIES + 1,
>> +				sizeof(*c->table), GFP_KERNEL);
>> +	if (!c->table)
>> +		return -ENOMEM;
>> +
>> +	for (i = 0; i < LUT_MAX_ENTRIES; i++) {
>> +		data = readl_relaxed(c->lut_base + i * LUT_ROW_SIZE);
>> +		src = ((data & GENMASK(31, 30)) >> 30);
>> +		lval = (data & GENMASK(7, 0));
>> +		core_count = CORE_COUNT_VAL(data);
> 
> Why do you need this here ? And why do below in case this doesn't
> match max-cores count ?
> 
>> +
>> +		if (!src)
>> +			c->table[i].frequency = INIT_RATE / 1000;
>> +		else
>> +			c->table[i].frequency = XO_RATE * lval / 1000;
>> +
>> +		c->table[i].driver_data = 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)
>> +			c->table[i].frequency = CPUFREQ_ENTRY_INVALID;
>> +
>> +		/*
>> +		 * Two of the same frequencies with the same core counts means
>> +		 * end of table.
>> +		 */
>> +		if (i > 0 && c->table[i - 1].driver_data ==
>> +					c->table[i].driver_data
>> +					&& prev_cc == core_count) {
>> +			struct cpufreq_frequency_table *prev = &c->table[i - 1];
>> +
>> +			if (prev->frequency == CPUFREQ_ENTRY_INVALID) {
>> +				prev->flags = CPUFREQ_BOOST_FREQ;
>> +				prev->frequency = prev->driver_data;
>> +			}
>> +
>> +			break;
>> +		}
>> +		prev_cc = core_count;
>> +	}
>> +	c->table[i].frequency = CPUFREQ_TABLE_END;
>> +
>> +	return 0;
>> +}
>> +
>> +static int qcom_get_related_cpus(struct device_node *np, struct cpumask *m)
>> +{
>> +	struct device_node *dev_phandle;
>> +	struct device *cpu_dev;
>> +	int cpu, i = 0, ret = -ENOENT;
>> +
>> +	dev_phandle = of_parse_phandle(np, "qcom,cpulist", i++);
> 
> TBH, I am not a great fan of the CPU phandle list you have created
> here. Lets see what Rob has to say on this.
> 
>> +	while (dev_phandle) {
>> +		for_each_possible_cpu(cpu) {
>> +			cpu_dev = get_cpu_device(cpu);
>> +			if (cpu_dev && cpu_dev->of_node == dev_phandle) {
>> +				cpumask_set_cpu(cpu, m);
>> +				ret = 0;
> 
> Maybe just remove this line ...
> 
>> +				break;
>> +			}
>> +		}
>> +		dev_phandle = of_parse_phandle(np, "qcom,cpulist", i++);
>> +	}
>> +
>> +	return ret;
> 
> and check for empty cpumask for an error here.
> 
>> +}
>> +
>> +static int qcom_cpu_resources_init(struct platform_device *pdev,
>> +						struct device_node *np)
> 
> You may want to align these properly. Try running checkpatch with
> --strict option.
> 
>> +{
>> +	struct cpufreq_qcom *c;
>> +	struct resource res;
>> +	struct device *dev = &pdev->dev;
>> +	void __iomem *en_base;
>> +	int cpu, index = 0, ret;
> 
> Why initialize index here ?
> 
>> +
>> +	c = devm_kzalloc(dev, sizeof(*c), GFP_KERNEL);
> 
> Check for a valid 'c' here ?
> 
>> +
>> +	res = platform_get_resource_byname(dev, IORESOURCE_MEM, "en_base");
> 
> You are assigning a pointer to a structure here :(
> 
>> +	if (!res) {
>> +		dev_err(dev, "Enable base not defined for %s\n", np->name);
>> +		return ret;
>> +	}
>> +
>> +	en_base = devm_ioremap(dev, res->start, resource_size(res));
> 
> You don't get a build error for doing res->start here ? Looks like you
> sent a driver upstream which doesn't even build.
> 
>> +	if (!en_base) {
>> +		dev_err(dev, "Unable to map %s en-base\n", np->name);
>> +		return -ENOMEM;
>> +	}
>> +
>> +	/* FW should be enabled state to proceed */
>> +	if (!(readl_relaxed(en_base) & 0x1)) {
>> +		dev_err(dev, "%s firmware not enabled\n", np->name);
>> +		return -ENODEV;
>> +	}
>> +
>> +	devm_iounmap(&pdev->dev, en_base);
>> +
>> +	index = of_property_match_string(np, "reg-names", "perf_base");
>> +	if (index < 0)
>> +		return index;
>> +
>> +	if (of_address_to_resource(np, index, &res))
>> +		return -ENOMEM;
>> +
>> +	c->perf_base = devm_ioremap(dev, res.start, resource_size(&res));
>> +	if (!c->perf_base) {
>> +		dev_err(dev, "Unable to map %s perf-base\n", np->name);
>> +		return -ENOMEM;
>> +	}
>> +
>> +	index = of_property_match_string(np, "reg-names", "lut_base");
>> +	if (index < 0)
>> +		return index;
>> +
>> +	if (of_address_to_resource(np, index, &res))
>> +		return -ENOMEM;
>> +
>> +	c->lut_base = devm_ioremap(dev, res.start, resource_size(&res));
>> +	if (!c->lut_base) {
>> +		dev_err(dev, "Unable to map %s lut-base\n", np->name);
>> +		return -ENOMEM;
>> +	}
>> +
>> +	ret = qcom_get_related_cpus(np, &c->related_cpus);
>> +	if (ret) {
>> +		dev_err(dev, "%s failed to get core phandles\n", np->name);
>> +		return ret;
>> +	}
>> +
>> +	c->max_cores = cpumask_weight(&c->related_cpus);
>> +
>> +	ret = qcom_read_lut(pdev, c);
>> +	if (ret) {
>> +		dev_err(dev, "%s failed to read LUT\n", np->name);
>> +		return ret;
>> +	}
>> +
>> +	for_each_cpu(cpu, &c->related_cpus)
>> +		qcom_freq_domain_map[cpu] = c;
>> +
>> +	return 0;
>> +}
>> +
>> +static int qcom_resources_init(struct platform_device *pdev)
>> +{
>> +	struct device_node *np;
>> +	int ret = -ENODEV;
>> +
>> +	for_each_available_child_of_node(pdev->dev.of_node, np) {
>> +		if (of_device_is_compatible(np, "cpufreq")) {
>> +			ret = qcom_cpu_resources_init(pdev, np);
>> +			if (ret)
>> +				return ret;
>> +		}
>> +	}
>> +
>> +	return ret;
> 
> Don't initialize ret to -ENODEV, rather return -ENODEV directly here.
> That makes it more readable.
> 
>> +}
>> +
>> +static int qcom_cpufreq_fw_driver_probe(struct platform_device *pdev)
>> +{
>> +	int rc = 0;
> 
> Don't need to initialize to 0 here.
> 
>> +
>> +	/* Get the bases of cpufreq for domains */
>> +	rc = qcom_resources_init(pdev);
>> +	if (rc) {
>> +		dev_err(&pdev->dev, "CPUFreq resource init failed\n");
>> +		return rc;
>> +	}
>> +
>> +	rc = cpufreq_register_driver(&cpufreq_qcom_fw_driver);
>> +	if (rc) {
>> +		dev_err(&pdev->dev, "CPUFreq FW driver failed to register\n");
>> +		return rc;
>> +	}
>> +
>> +	dev_info(&pdev->dev, "QCOM CPUFreq FW driver inited\n");
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct of_device_id match_table[] = {
>> +	{ .compatible = "qcom,cpufreq-fw" },
>> +	{}
>> +};
>> +
>> +static struct platform_driver qcom_cpufreq_fw_driver = {
>> +	.probe = qcom_cpufreq_fw_driver_probe,
>> +	.driver = {
>> +		.name = "qcom-cpufreq-fw",
>> +		.of_match_table = match_table,
>> +		.owner = THIS_MODULE,
>> +	},
>> +};
>> +
>> +static int __init qcom_cpufreq_fw_init(void)
>> +{
>> +	return platform_driver_register(&qcom_cpufreq_fw_driver);
>> +}
>> +subsys_initcall(qcom_cpufreq_fw_init);
> 
> Why this for a driver which can be built as a module ? You really want
> it to be built as a module ?
> 
>> +
>> +static void __exit qcom_cpufreq_fw_exit(void)
>> +{
>> +	platform_driver_unregister(&qcom_cpufreq_fw_driver);
>> +}
> 
> But you don't unregister the cpufreq driver ?
> 
>> +module_exit(qcom_cpufreq_fw_exit);
>> +
>> +MODULE_DESCRIPTION("QCOM CPU Frequency FW");
>> +MODULE_LICENSE("GPL v2");
>> --
>> Qualcomm INDIA, on behalf of Qualcomm Innovation Center, Inc.is a member
>> of the Code Aurora Forum, hosted by the  Linux Foundation.
> 

-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation.

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