Re: [PATCH v10 2/2] cpufreq: qcom-hw: Add support for QCOM cpufreq HW driver
From: Taniya Das
Date: Sat Dec 01 2018 - 22:47:08 EST
Hello Matthias,
On 11/22/2018 12:11 AM, Matthias Kaehlcke wrote:
Hi Taniya,
thanks for respinning, a few nits inline.
On Wed, Nov 21, 2018 at 04:12:47PM +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@xxxxxxxxxxxxxx>
Signed-off-by: Taniya Das <tdas@xxxxxxxxxxxxxx>
---
drivers/cpufreq/Kconfig.arm | 11 ++
drivers/cpufreq/Makefile | 1 +
drivers/cpufreq/qcom-cpufreq-hw.c | 346 ++++++++++++++++++++++++++++++++++++++
3 files changed, 358 insertions(+)
create mode 100644 drivers/cpufreq/qcom-cpufreq-hw.c
diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index 4e1131e..688f102 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -114,6 +114,17 @@ config ARM_QCOM_CPUFREQ_KRYO
If in doubt, say N.
+config ARM_QCOM_CPUFREQ_HW
+ tristate "QCOM CPUFreq HW driver"
+ depends on ARCH_QCOM || COMPILE_TEST
+ 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.
+
config ARM_S3C_CPUFREQ
bool
help
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index d5ee456..789b2e0 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -62,6 +62,7 @@ obj-$(CONFIG_ARM_OMAP2PLUS_CPUFREQ) += omap-cpufreq.o
obj-$(CONFIG_ARM_PXA2xx_CPUFREQ) += pxa2xx-cpufreq.o
obj-$(CONFIG_PXA3xx) += pxa3xx-cpufreq.o
obj-$(CONFIG_ARM_QCOM_CPUFREQ_KRYO) += qcom-cpufreq-kryo.o
+obj-$(CONFIG_ARM_QCOM_CPUFREQ_HW) += qcom-cpufreq-hw.o
obj-$(CONFIG_ARM_S3C2410_CPUFREQ) += s3c2410-cpufreq.o
obj-$(CONFIG_ARM_S3C2412_CPUFREQ) += s3c2412-cpufreq.o
obj-$(CONFIG_ARM_S3C2416_CPUFREQ) += s3c2416-cpufreq.o
diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
new file mode 100644
index 0000000..6390e85
--- /dev/null
+++ b/drivers/cpufreq/qcom-cpufreq-hw.c
@@ -0,0 +1,346 @@
+// 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 LUT_MAX_ENTRIES 40U
+#define CORE_COUNT_VAL(val) (((val) & (GENMASK(18, 16))) >> 16)
+#define LUT_ROW_SIZE 32
+#define CLK_HW_DIV 2
+
+/* Register offsets */
+#define REG_ENABLE 0x0
+#define REG_LUT_TABLE 0x110
+#define REG_PERF_STATE 0x920
+
+struct cpufreq_qcom {
+ struct cpufreq_frequency_table *table;
+ void __iomem *perf_base;
nit: is this really a base address? It's the address of the perf state
register, right? Better name it 'perf_state_reg'/'reg_perf_state' or
similar (just 'perf_state' might be confusing, I'd expect a variable
with this name to hold a state, not an address).
I have updated the name to "perf_state_reg".
+ cpumask_t related_cpus;
+ unsigned int max_cores;
+ unsigned long xo_rate;
+ unsigned long cpu_hw_rate;
+};
+
+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->perf_base);
+
+ 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->perf_base);
+ 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->perf_base);
+
+ 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, void __iomem *base)
+{
+ 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(base + REG_LUT_TABLE + 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 = c->cpu_hw_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;
+
+ /*
+ * Two of the same frequencies with the same core counts means
+ * end of table.
+ */
+ if (i > 0 && c->table[i - 1].frequency ==
+ c->table[i].frequency && prev_cc == core_count) {
+ struct cpufreq_frequency_table *prev = &c->table[i - 1];
+
+ if (prev_freq == CPUFREQ_ENTRY_INVALID)
+ prev->flags = CPUFREQ_BOOST_FREQ;
+ break;
+ }
+ prev_cc = core_count;
+ prev_freq = cur_freq;
+ }
+
+ c->table[i].frequency = CPUFREQ_TABLE_END;
+
+ return 0;
+}
+
+static int qcom_get_related_cpus(int index, struct cpumask *m)
+{
+ struct device_node *cpu_np;
+ struct of_phandle_args args;
+ int cpu, ret;
+
+ for_each_possible_cpu(cpu) {
+ cpu_np = of_cpu_device_node_get(cpu);
+ if (!cpu_np)
+ continue;
+
+ ret = of_parse_phandle_with_args(cpu_np, "qcom,freq-domain",
+ "#freq-domain-cells", 0,
+ &args);
+ of_node_put(cpu_np);
+ if (ret < 0)
+ continue;
+
+ if (index == args.args[0])
+ cpumask_set_cpu(cpu, m);
+ }
+
+ return 0;
+}
+
+static int qcom_cpu_resources_init(struct platform_device *pdev,
+ unsigned int cpu, int index,
+ unsigned long xo_rate,
+ unsigned long cpu_hw_rate)
+{
+ struct cpufreq_qcom *c;
+ struct resource *res;
+ struct device *dev = &pdev->dev;
+ void __iomem *base;
+ int ret, cpu_r;
+
+ if (qcom_freq_domain_map[cpu])
+ return 0;
+
+ c = devm_kzalloc(dev, sizeof(*c), GFP_KERNEL);
+ if (!c)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, index);
+ base = devm_ioremap_resource(dev, res);
+ if (IS_ERR(base))
+ return PTR_ERR(base);
+
+ /* HW should be in enabled state to proceed */
+ if (!(readl_relaxed(base + REG_ENABLE) & 0x1)) {
+ dev_err(dev, "Domain-%d cpufreq hardware not enabled\n", index);
+ return -ENODEV;
+ }
+
+ ret = qcom_get_related_cpus(index, &c->related_cpus);
+ if (ret) {
+ dev_err(dev, "Domain-%d failed to get related CPUs\n", index);
+ return ret;
+ }
+
+ c->max_cores = cpumask_weight(&c->related_cpus);
+ if (!c->max_cores)
+ return -ENOENT;
+
+ c->xo_rate = xo_rate;
+ c->cpu_hw_rate = cpu_hw_rate;
+ c->perf_base = base + REG_PERF_STATE;
+
+ ret = qcom_cpufreq_hw_read_lut(pdev, c, base);
+ if (ret) {
+ dev_err(dev, "Domain-%d failed to read LUT\n", index);
+ return ret;
+ }
+
+ for_each_cpu(cpu_r, &c->related_cpus)
+ qcom_freq_domain_map[cpu_r] = c;
+
+ return 0;
+}
+
+static int qcom_resources_init(struct platform_device *pdev)
+{
+ struct device_node *cpu_np;
+ struct of_phandle_args args;
+ struct clk *clk;
+ unsigned int cpu;
+ unsigned long xo_rate, cpu_hw_rate;
+ int ret;
+
+ clk = clk_get(&pdev->dev, "xo");
+ if (IS_ERR(clk))
+ return PTR_ERR(clk);
+
+ xo_rate = clk_get_rate(clk);
+
+ clk_put(clk);
+
+ clk = clk_get(&pdev->dev, "gcc_cpuss_gpll0_clk_src");
As commented on the binding patch, I'm not sure if this is the correct
name for this clock input from the POV of this IP block. Just a doubt
at this point, I don't have/find the hardware documentation to suggest
something better.
The clock name used in the latest series is "alternate".
+ if (IS_ERR(clk))
+ return PTR_ERR(clk);
+
+ cpu_hw_rate = clk_get_rate(clk) / CLK_HW_DIV;
+
+ clk_put(clk);
+
+ for_each_possible_cpu(cpu) {
+ cpu_np = of_cpu_device_node_get(cpu);
+ if (!cpu_np) {
+ dev_dbg(&pdev->dev, "Failed to get cpu %d device\n",
+ cpu);
+ continue;
+ }
+
+ ret = of_parse_phandle_with_args(cpu_np, "qcom,freq-domain",
+ "#freq-domain-cells", 0,
+ &args);
+ of_node_put(cpu_np);
+ if (ret < 0)
+ return ret;
+
+ ret = qcom_cpu_resources_init(pdev, cpu, args.args[0],
+ xo_rate, cpu_hw_rate);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int qcom_cpufreq_hw_driver_probe(struct platform_device *pdev)
+{
+ int rc;
+
+ /* 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_hw_driver);
+ if (rc) {
+ dev_err(&pdev->dev, "CPUFreq HW driver failed to register\n");
+ return rc;
+ }
+
+ dev_dbg(&pdev->dev, "QCOM CPUFreq HW driver initialized\n");
+
+ return 0;
+}
+
+static const struct of_device_id qcom_cpufreq_hw_match[] = {
+ { .compatible = "qcom,cpufreq-hw" },
+ {}
+};
+
+static struct platform_driver qcom_cpufreq_hw_driver = {
+ .probe = qcom_cpufreq_hw_driver_probe,
+ .driver = {
+ .name = "qcom-cpufreq-hw",
+ .of_match_table = qcom_cpufreq_hw_match,
+ },
+};
+
+static int __init qcom_cpufreq_hw_init(void)
+{
+ return platform_driver_register(&qcom_cpufreq_hw_driver);
+}
+subsys_initcall(qcom_cpufreq_hw_init);
I'm still not convinced that a subsys_initcall is needed (instead of
module_init or device_initcall), as mentioned in the review of v7
it causes problems when registering CPU cooling devices, but we can
also fix this when support for cooling devices is added ;-)
Yes, sure, we could revisit this.
+static void __exit qcom_cpufreq_hw_exit(void)
+{
+ cpufreq_unregister_driver(&cpufreq_qcom_hw_driver);
+ platform_driver_unregister(&qcom_cpufreq_hw_driver);
+}
+module_exit(qcom_cpufreq_hw_exit);
+
+MODULE_DESCRIPTION("QTI CPUFREQ HW Driver");
nit: make it 'QCOM CPUFreq HW driver' for consistency?
Thanks, have taken care in the latest patch.
Cheers
Matthias
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