[PATCH v13 2/2] cpufreq: qcom-hw: Add support for QCOM cpufreq HW driver

[Taniya Das <tdas@codeaurora.org>]

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: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Taniya Das <tdas@codeaurora.org>
---
 drivers/cpufreq/Kconfig.arm       |  11 ++
 drivers/cpufreq/Makefile          |   1 +
 drivers/cpufreq/qcom-cpufreq-hw.c | 308 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 320 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..08c071b 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -61,6 +61,7 @@ obj-$(CONFIG_MACH_MVEBU_V7)		+= mvebu-cpufreq.o
 obj-$(CONFIG_ARM_OMAP2PLUS_CPUFREQ)	+= omap-cpufreq.o
 obj-$(CONFIG_ARM_PXA2xx_CPUFREQ)	+= pxa2xx-cpufreq.o
 obj-$(CONFIG_PXA3xx)			+= pxa3xx-cpufreq.o
+obj-$(CONFIG_ARM_QCOM_CPUFREQ_HW)	+= qcom-cpufreq-hw.o
 obj-$(CONFIG_ARM_QCOM_CPUFREQ_KRYO)	+= qcom-cpufreq-kryo.o
 obj-$(CONFIG_ARM_S3C2410_CPUFREQ)	+= s3c2410-cpufreq.o
 obj-$(CONFIG_ARM_S3C2412_CPUFREQ)	+= s3c2412-cpufreq.o
diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
new file mode 100644
index 0000000..d83939a
--- /dev/null
+++ b/drivers/cpufreq/qcom-cpufreq-hw.c
@@ -0,0 +1,308 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/bitfield.h>
+#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>
+#include <linux/slab.h>
+
+#define LUT_MAX_ENTRIES			40U
+#define LUT_SRC				GENMASK(31, 30)
+#define LUT_L_VAL			GENMASK(7, 0)
+#define LUT_CORE_COUNT			GENMASK(18, 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
+
+static unsigned long cpu_hw_rate, xo_rate;
+static struct platform_device *global_pdev;
+
+static int qcom_cpufreq_hw_target_index(struct cpufreq_policy *policy,
+					unsigned int index)
+{
+	void __iomem *perf_state_reg = policy->driver_data;
+
+	writel_relaxed(index, perf_state_reg);
+
+	return 0;
+}
+
+static unsigned int qcom_cpufreq_hw_get(unsigned int cpu)
+{
+	void __iomem *perf_state_reg;
+	struct cpufreq_policy *policy;
+	unsigned int index;
+
+	policy = cpufreq_cpu_get_raw(cpu);
+	if (!policy)
+		return 0;
+
+	perf_state_reg = policy->driver_data;
+
+	index = readl_relaxed(perf_state_reg);
+	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)
+{
+	void __iomem *perf_state_reg = policy->driver_data;
+	int index;
+
+	index = policy->cached_resolved_idx;
+	if (index < 0)
+		return 0;
+
+	writel_relaxed(index, perf_state_reg);
+
+	return policy->freq_table[index].frequency;
+}
+
+static int qcom_cpufreq_hw_read_lut(struct device *dev,
+				    struct cpufreq_policy *policy,
+				    void __iomem *base)
+{
+	u32 data, src, lval, i, core_count, prev_cc = 0, prev_freq = 0, freq;
+	unsigned int max_cores = cpumask_weight(policy->cpus);
+	struct cpufreq_frequency_table	*table;
+
+	table = kcalloc(LUT_MAX_ENTRIES + 1, sizeof(*table), GFP_KERNEL);
+	if (!table)
+		return -ENOMEM;
+
+	for (i = 0; i < LUT_MAX_ENTRIES; i++) {
+		data = readl_relaxed(base + REG_LUT_TABLE + i * LUT_ROW_SIZE);
+		src = FIELD_GET(LUT_SRC, data);
+		lval = FIELD_GET(LUT_L_VAL, data);
+		core_count = FIELD_GET(LUT_CORE_COUNT, data);
+
+		if (src)
+			freq = xo_rate * lval / 1000;
+		else
+			freq = cpu_hw_rate / 1000;
+
+		/* Ignore boosts in the middle of the table */
+		if (core_count != max_cores) {
+			table[i].frequency = CPUFREQ_ENTRY_INVALID;
+		} else {
+			table[i].frequency = freq;
+			dev_dbg(dev, "index=%d freq=%d, core_count %d\n", i,
+				freq, core_count);
+		}
+
+		/*
+		 * Two of the same frequencies with the same core counts means
+		 * end of table
+		 */
+		if (i > 0 && prev_freq == freq && prev_cc == core_count) {
+			struct cpufreq_frequency_table *prev = &table[i - 1];
+
+			/*
+			 * Only treat the last frequency that might be a boost
+			 * as the boost frequency
+			 */
+			if (prev_cc != max_cores) {
+				prev->frequency = prev_freq;
+				prev->flags = CPUFREQ_BOOST_FREQ;
+			}
+
+			break;
+		}
+
+		prev_cc = core_count;
+		prev_freq = freq;
+	}
+
+	table[i].frequency = CPUFREQ_TABLE_END;
+	policy->freq_table = table;
+
+	return 0;
+}
+
+static void 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);
+	}
+}
+
+static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
+{
+	struct device *dev = &global_pdev->dev;
+	struct of_phandle_args args;
+	struct device_node *cpu_np;
+	struct resource *res;
+	void __iomem *base;
+	int ret, index;
+
+	cpu_np = of_cpu_device_node_get(policy->cpu);
+	if (!cpu_np)
+		return -EINVAL;
+
+	ret = of_parse_phandle_with_args(cpu_np, "qcom,freq-domain",
+					 "#freq-domain-cells", 0, &args);
+	of_node_put(cpu_np);
+	if (ret)
+		return ret;
+
+	index = args.args[0];
+
+	res = platform_get_resource(global_pdev, IORESOURCE_MEM, index);
+	if (!res)
+		return -ENODEV;
+
+	base = devm_ioremap(dev, res->start, resource_size(res));
+	if (!base)
+		return -ENOMEM;
+
+	/* 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);
+		ret = -ENODEV;
+		goto error;
+	}
+
+	qcom_get_related_cpus(index, policy->cpus);
+	if (!cpumask_weight(policy->cpus)) {
+		dev_err(dev, "Domain-%d failed to get related CPUs\n", index);
+		ret = -ENOENT;
+		goto error;
+	}
+
+	policy->driver_data = base + REG_PERF_STATE;
+
+	ret = qcom_cpufreq_hw_read_lut(dev, policy, base);
+	if (ret) {
+		dev_err(dev, "Domain-%d failed to read LUT\n", index);
+		goto error;
+	}
+
+	policy->fast_switch_possible = true;
+
+	return 0;
+error:
+	devm_iounmap(dev, base);
+	return ret;
+}
+
+static int qcom_cpufreq_hw_cpu_exit(struct cpufreq_policy *policy)
+{
+	void __iomem *base = policy->driver_data - REG_PERF_STATE;
+
+	kfree(policy->freq_table);
+	devm_iounmap(&global_pdev->dev, base);
+
+	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,
+	.exit		= qcom_cpufreq_hw_cpu_exit,
+	.fast_switch    = qcom_cpufreq_hw_fast_switch,
+	.name		= "qcom-cpufreq-hw",
+	.attr		= qcom_cpufreq_hw_attr,
+};
+
+static int qcom_cpufreq_hw_driver_probe(struct platform_device *pdev)
+{
+	struct clk *clk;
+	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, "alternate");
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	cpu_hw_rate = clk_get_rate(clk) / CLK_HW_DIV;
+	clk_put(clk);
+
+	global_pdev = pdev;
+
+	ret = cpufreq_register_driver(&cpufreq_qcom_hw_driver);
+	if (ret)
+		dev_err(&pdev->dev, "CPUFreq HW driver failed to register\n");
+	else
+		dev_dbg(&pdev->dev, "QCOM CPUFreq HW driver initialized\n");
+
+	return ret;
+}
+
+static int qcom_cpufreq_hw_driver_remove(struct platform_device *pdev)
+{
+	return cpufreq_unregister_driver(&cpufreq_qcom_hw_driver);
+}
+
+static const struct of_device_id qcom_cpufreq_hw_match[] = {
+	{ .compatible = "qcom,cpufreq-hw" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, qcom_cpufreq_hw_match);
+
+static struct platform_driver qcom_cpufreq_hw_driver = {
+	.probe = qcom_cpufreq_hw_driver_probe,
+	.remove = qcom_cpufreq_hw_driver_remove,
+	.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);
+
+static void __exit qcom_cpufreq_hw_exit(void)
+{
+	platform_driver_unregister(&qcom_cpufreq_hw_driver);
+}
+module_exit(qcom_cpufreq_hw_exit);
+
+MODULE_DESCRIPTION("QCOM CPUFREQ HW Driver");
+MODULE_LICENSE("GPL v2");
--
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