Messages in this thread | | | Subject | Re: [PATCH v5 2/2] cpufreq: qcom-hw: Add support for QCOM cpufreq HW driver | From | Taniya Das <> | Date | Tue, 17 Jul 2018 11:27:22 +0530 |
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Hello Matthias,
Thanks for your review comments.
On 7/13/2018 5:49 AM, Matthias Kaehlcke wrote: > Hi, > > On Thu, Jul 12, 2018 at 11:35:45PM +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@codeaurora.org> >> Signed-off-by: Taniya Das <tdas@codeaurora.org> >> --- >> drivers/cpufreq/Kconfig.arm | 10 ++ >> drivers/cpufreq/Makefile | 1 + >> drivers/cpufreq/qcom-cpufreq-hw.c | 344 ++++++++++++++++++++++++++++++++++++++ >> 3 files changed, 355 insertions(+) >> create mode 100644 drivers/cpufreq/qcom-cpufreq-hw.c >> >> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm >> index 52f5f1a..141ec3e 100644 >> --- a/drivers/cpufreq/Kconfig.arm >> +++ b/drivers/cpufreq/Kconfig.arm >> @@ -312,3 +312,13 @@ 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" >> + 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 interafce to the High-level OS. >> + The driver implements the cpufreq driver 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 fb4a2ec..1226a3e 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_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..fa25a95 >> --- /dev/null >> +++ b/drivers/cpufreq/qcom-cpufreq-hw.c >> @@ -0,0 +1,344 @@ >> +// 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 >> + >> +enum { >> + REG_ENABLE, >> + REG_LUT_TABLE, >> + REG_PERF_STATE, >> + >> + REG_ARRAY_SIZE, >> +}; >> + >> +struct cpufreq_qcom { >> + struct cpufreq_frequency_table *table; >> + struct device *dev; >> + const u16 *reg_offset; >> + void __iomem *base; >> + cpumask_t related_cpus; >> + unsigned int max_cores; > > Same comment as on v4: > > 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. Maybe it's the name from the datasheet? Should it still be > 'num_cores' or similer? >
Your understanding is correct. I would prefer to leave the naming as 'max_cores'.
>> +static struct cpufreq_qcom *qcom_freq_domain_map[NR_CPUS]; > > It would be an option to limit this to the number of CPU clusters and > allocate it dynamically when the driver is initialized (key = first > core in the cluster). Probably not worth the hassle with the limited > number of cores though. > >> +static int qcom_read_lut(struct platform_device *pdev, >> + struct cpufreq_qcom *c) >> +{ >> + struct device *dev = &pdev->dev; >> + unsigned int offset; >> + 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; >> + >> + offset = c->reg_offset[REG_LUT_TABLE]; >> + >> + for (i = 0; i < LUT_MAX_ENTRIES; i++) { >> + data = readl_relaxed(c->base + offset + i * LUT_ROW_SIZE); >> + src = ((data & GENMASK(31, 30)) >> 30); >> + lval = (data & GENMASK(7, 0)); >> + core_count = CORE_COUNT_VAL(data); >> + >> + if (src == 0) >> + c->table[i].frequency = INIT_RATE / 1000; >> + else >> + c->table[i].frequency = XO_RATE * lval / 1000; > > You changed the condition from '!src' to 'src == 0'. My suggestion on > v4 was in part about a negative condition, but also about the > order. If it doesn't obstruct the code otherwise I think for an if-else > branch it is good practice to handle the more common case first and > then the 'exception'. I would expect most entries to have an actual > rate. Just a nit in any case, feel free to ignore if you prefer as is. >
Thanks, Sure, I would take care of it in the next series.
>> +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; >> + unsigned int offset, cpu_r; >> + int ret; >> + >> + c = devm_kzalloc(dev, sizeof(*c), GFP_KERNEL); >> + if (!c) >> + return -ENOMEM; >> + >> + c->reg_offset = of_device_get_match_data(&pdev->dev); >> + if (!c->reg_offset) >> + return -EINVAL; >> + >> + if (of_address_to_resource(np, 0, &res)) >> + return -ENOMEM; >> + >> + c->base = devm_ioremap(dev, res.start, resource_size(&res)); >> + if (!c->base) { >> + dev_err(dev, "Unable to map %s base\n", np->name); >> + return -ENOMEM; >> + } >> + >> + offset = c->reg_offset[REG_ENABLE]; >> + >> + /* HW should be in enabled state to proceed */ >> + if (!(readl_relaxed(c->base + offset) & 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; >> + >> + ret = qcom_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; > > If the general code structure remains as is (see my comment below) > the assignment could be done in a 'if (cpu == cpu_r)' branch instead > of first assigning and then overwriting it for 'cpu != cpu_r'. > >> + >> + /* Related CPUs to keep a single copy */ >> + cpu_r = cpumask_first(&c->related_cpus); >> + if (cpu != cpu_r) { >> + qcom_freq_domain_map[cpu] = qcom_freq_domain_map[cpu_r]; >> + devm_kfree(dev, c); >> + } > > Couldn't we do this at the beginning of the function instead of going > through allocation, ioremap, read_lut for every core only to throw the > information away later for the 'related' CPUs? > > qcom_cpu_resources_init() is called with increasing 'cpu' values, hence the > 'first' CPU of the cluster is already initialized when the 'related' > ones are processed. >
I would be moving the code to the beginning of the function.
>> + return 0; >> +} >> + >> +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; >> +} > > Thanks > > Matthias >
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