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Message-ID: <20180711203717.GS129942@google.com>
Date: Wed, 11 Jul 2018 13:37:17 -0700
From: Matthias Kaehlcke <mka@...omium.org>
To: Taniya Das <tdas@...eaurora.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>,
devicetree@...r.kernel.org, robh@...nel.org, skannan@...eaurora.org
Subject: Re: [PATCH v4 2/2] cpufreq: qcom-fw: Add support for QCOM cpufreq FW
driver
Hi,
On Tue, Jun 12, 2018 at 04:32:35PM +0530, Taniya Das wrote:
> The CPUfreq FW present in some QCOM chipsets offloads the steps necessary
> for changing the frequency of CPUs. The driver implements the cpufreq
> driver interface for this firmware.
>
> Signed-off-by: Saravana Kannan <skannan@...eaurora.org>
> Signed-off-by: Taniya Das <tdas@...eaurora.org>
> ---
> drivers/cpufreq/Kconfig.arm | 9 +
> drivers/cpufreq/Makefile | 1 +
> drivers/cpufreq/qcom-cpufreq-fw.c | 336 ++++++++++++++++++++++++++++++++++++++
> 3 files changed, 346 insertions(+)
> create mode 100644 drivers/cpufreq/qcom-cpufreq-fw.c
>
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index 52f5f1a..2683716 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -312,3 +312,12 @@ config ARM_PXA2xx_CPUFREQ
> This add the CPUFreq driver support for Intel PXA2xx SOCs.
>
> If in doubt, say N.
> +
> +config ARM_QCOM_CPUFREQ_FW
> + bool "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 fb4a2ec..34691a2 100644
> --- a/drivers/cpufreq/Makefile
> +++ b/drivers/cpufreq/Makefile
> @@ -86,6 +86,7 @@ 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..62f4452
> --- /dev/null
> +++ b/drivers/cpufreq/qcom-cpufreq-fw.c
> @@ -0,0 +1,336 @@
> +// 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;
Why *max*_cores? This seems to be the number of CPUs in a cluster and
qcom_read_lut() expects the core count read from the LUT to match
exactly.
> +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, prev_freq, cur_freq;
> +
> + 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);
> +
> + if (!src)
> + c->table[i].frequency = INIT_RATE / 1000;
> + else
> + c->table[i].frequency = XO_RATE * lval / 1000;
nit: any particular reason to use negative logic here? Why not check
for 'src[ != NULL]', which also seems to be the more common case.
> +static int qcom_get_related_cpus(struct device_node *np, struct cpumask *m)
> +{
> + struct device_node *cpu_np, *freq_np;
> + int cpu;
> +
> + for_each_possible_cpu(cpu) {
> + cpu_np = of_cpu_device_node_get(cpu);
> + if (!cpu_np)
> + continue;
> + freq_np = of_parse_phandle(cpu_np, "qcom,freq-domain", 0);
> + if (!freq_np)
> + continue;
> + if (freq_np == np)
> + cpumask_set_cpu(cpu, m);
missing 'of_node_put(cpu_np)'. You might want to do it at the end of
the loop and use a 'goto' above instead of 'continue'.
> +static int qcom_cpu_resources_init(struct platform_device *pdev,
> + struct device_node *np, unsigned int cpu)
> +{
> + struct cpufreq_qcom *c;
> + struct resource res;
> + struct device *dev = &pdev->dev;
> + void __iomem *en_base;
> + int index, ret;
> +
> + c = devm_kzalloc(dev, sizeof(*c), GFP_KERNEL);
> + if (!c)
> + return -ENOMEM;
> +
> + index = of_property_match_string(np, "reg-names", "enable");
> + if (index < 0)
> + return index;
> +
> + if (of_address_to_resource(np, index, &res))
> + return -ENOMEM;
> +
> + en_base = devm_ioremap(dev, res.start, resource_size(&res));
> + if (!en_base) {
> + dev_err(dev, "Unable to map %s enable-base\n", np->name);
> + return -ENOMEM;
> + }
> +
> + /* FW should be in 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");
> + 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");
> + 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;
> + }
The of_property_match_string() - of_address_to_resource() -
devm_ioremap() pattern is repeated 3x. In case the binding doesn't
change (there is discussion on the DT patch) you might want to move
this to a helper.
> +static int qcom_resources_init(struct platform_device *pdev)
> +{
> + struct device_node *np, *cpu_np;
> + unsigned int cpu;
> + int ret;
> +
> + for_each_possible_cpu(cpu) {
> + cpu_np = of_cpu_device_node_get(cpu);
> + if (!cpu_np) {
> + dev_err(&pdev->dev, "Failed to get cpu %d device\n",
> + cpu);
> + continue;
> + }
> +
> + np = of_parse_phandle(cpu_np, "qcom,freq-domain", 0);
> + if (!np) {
> + dev_err(&pdev->dev, "Failed to get freq-domain device\n");
of_node_put(cpu_np);
> + return -EINVAL;
> + }
> +
> + of_node_put(cpu_np);
> +
> + ret = qcom_cpu_resources_init(pdev, np, cpu);
> + if (ret)
> + return ret;
> + }
> +
> + return 0;
Cheers
Matthias
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