Re: [PATCH v7 2/2] cpufreq: qcom-hw: Add support for QCOM cpufreq HW driver
From: Matthias Kaehlcke <mka@chromium.org>
Date: 2018-08-29 18:01:27
Also in:
linux-pm, lkml
Hi Taniya, On Tue, Jul 24, 2018 at 04:12:50PM +0530, Taniya Das wrote:
quoted hunk ↗ jump to hunk
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 <redacted> Signed-off-by: Taniya Das <redacted> --- 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.cdiff --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;
'dev' is not used and can be removed.
...
+static int qcom_cpu_resources_init(struct platform_device *pdev,
+ struct device_node *np, unsigned int cpu,
+ unsigned long xo_rate)
+{
+ struct cpufreq_qcom *c;
+ struct resource res;
+ struct device *dev = &pdev->dev;
+ const u16 *offsets;
+ int ret, i, cpu_first, cpu_r;
+ void __iomem *base;
+
+ if (qcom_freq_domain_map[cpu])
+ return 0;
+
+ c = devm_kzalloc(dev, sizeof(*c), GFP_KERNEL);
+ if (!c)
+ return -ENOMEM;
+
+ offsets = of_device_get_match_data(&pdev->dev);
+ if (!offsets)
+ return -EINVAL;
+
+ if (of_address_to_resource(np, 0, &res))
+ return -ENOMEM;
+
+ base = devm_ioremap_resource(dev, &res);
+ if (!base)
+ return -ENOMEM;
+
+ for (i = REG_ENABLE; i < REG_ARRAY_SIZE; i++)
+ c->reg_bases[i] = base + offsets[i];
+
+ /* HW should be in enabled state to proceed */
+ if (!(readl_relaxed(c->reg_bases[REG_ENABLE]) & 0x1)) {
+ dev_err(dev, "%s cpufreq hardware not enabled\n", np->name);
+ return -ENODEV;
+ }
+
+ ret = qcom_get_related_cpus(np, &c->related_cpus);
+ if (ret) {
+ dev_err(dev, "%s failed to get related CPUs\n", np->name);
+ return ret;
+ }
+
+ c->max_cores = cpumask_weight(&c->related_cpus);
+ if (!c->max_cores)
+ return -ENOENT;
+
+ c->xo_rate = xo_rate;
+
+ ret = qcom_cpufreq_hw_read_lut(pdev, c);
+ if (ret) {
+ dev_err(dev, "%s failed to read LUT\n", np->name);
+ return ret;
+ }
+
+ qcom_freq_domain_map[cpu] = c;
+
+ /* Related CPUs */
+ cpu_first = cpumask_first(&c->related_cpus);
+
+ for_each_cpu(cpu_r, &c->related_cpus) {
+ if (cpu_r != cpu_first)
+ qcom_freq_domain_map[cpu_r] =
+ qcom_freq_domain_map[cpu_first];
+ }The above ten lines could be simplified to: for_each_cpu(cpu_r, &c->related_cpus) qcom_freq_domain_map[cpu_r] = c;
...
+static int __init qcom_cpufreq_hw_init(void)
+{
+ return platform_driver_register(&qcom_cpufreq_hw_driver);
+}
+subsys_initcall(qcom_cpufreq_hw_init);Is subsys_initcall used for a particular reason? It will cause problems when registering cooling devices, since the thermal device class is initialized through an fs_initcall, which are executed later. Most cpufreq drivers use module_init, device_initcall or late_initcall, can't this driver use one of those? Cheers Matthias