[PATCH v3 3/3] cpufreq: qcom-hw: Add CPU clock provider support

[Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>]

Qcom CPUFreq hardware (EPSS/OSM) controls clock and voltage to the CPU
cores. But this relationship is not represented with the clk framework
so far.

So, let's make the qcom-cpufreq-hw driver a clock provider. This makes the
clock producer/consumer relationship cleaner and is also useful for CPU
related frameworks like OPP to know the frequency at which the CPUs are
running.

The clock frequency provided by the driver is for each frequency domain.
We cannot get the frequency of each CPU core because, not all platforms
support per-core DCVS feature.

Also the frequency supplied by the driver is the actual frequency that
comes out of the EPSS/OSM block after the DCVS operation. This frequency is
not same as what the CPUFreq framework has set but it is the one that gets
supplied to the CPUs after throttling by LMh.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
---
 drivers/cpufreq/qcom-cpufreq-hw.c | 43 +++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
index 76f840636828..b824f1bb04f4 100644
--- a/drivers/cpufreq/qcom-cpufreq-hw.c
+++ b/drivers/cpufreq/qcom-cpufreq-hw.c
@@ -4,6 +4,7 @@
  */
 
 #include <linux/bitfield.h>
+#include <linux/clk-provider.h>
 #include <linux/cpufreq.h>
 #include <linux/init.h>
 #include <linux/interconnect.h>
@@ -53,6 +54,7 @@ struct qcom_cpufreq_data {
 	bool cancel_throttle;
 	struct delayed_work throttle_work;
 	struct cpufreq_policy *policy;
+	struct clk_hw cpu_clk;
 
 	bool per_core_dcvs;
 };
@@ -601,8 +603,20 @@ static struct cpufreq_driver cpufreq_qcom_hw_driver = {
 	.ready		= qcom_cpufreq_ready,
 };
 
+static unsigned long qcom_cpufreq_hw_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
+{
+	struct qcom_cpufreq_data *data = container_of(hw, struct qcom_cpufreq_data, cpu_clk);
+
+	return qcom_lmh_get_throttle_freq(data) / HZ_PER_KHZ;
+}
+
+static const struct clk_ops qcom_cpufreq_hw_clk_ops = {
+	.recalc_rate = qcom_cpufreq_hw_recalc_rate,
+};
+
 static int qcom_cpufreq_hw_driver_probe(struct platform_device *pdev)
 {
+	struct clk_hw_onecell_data *clk_data;
 	struct device *dev = &pdev->dev;
 	struct device *cpu_dev;
 	struct clk *clk;
@@ -645,8 +659,16 @@ static int qcom_cpufreq_hw_driver_probe(struct platform_device *pdev)
 
 	qcom_cpufreq.soc_data = of_device_get_match_data(dev);
 
+	clk_data = devm_kzalloc(dev, struct_size(clk_data, hws, num_domains), GFP_KERNEL);
+	if (!clk_data)
+		return -ENOMEM;
+
+	clk_data->num = num_domains;
+
 	for (i = 0; i < num_domains; i++) {
 		struct qcom_cpufreq_data *data = &qcom_cpufreq.data[i];
+		struct clk_init_data init = {};
+		const char *clk_name;
 		struct resource *res;
 		void __iomem *base;
 
@@ -658,6 +680,27 @@ static int qcom_cpufreq_hw_driver_probe(struct platform_device *pdev)
 
 		data->base = base;
 		data->res = res;
+
+		/* Register CPU clock for each frequency domain */
+		clk_name = devm_kasprintf(dev, GFP_KERNEL, "qcom_cpufreq%d", i);
+		init.name = clk_name;
+		init.flags = CLK_GET_RATE_NOCACHE;
+		init.ops = &qcom_cpufreq_hw_clk_ops;
+		data->cpu_clk.init = &init;
+
+		ret = devm_clk_hw_register(dev, &data->cpu_clk);
+		if (ret < 0) {
+			dev_err(dev, "Failed to register Qcom CPUFreq clock\n");
+			return ret;
+		}
+
+		clk_data->hws[i] = &data->cpu_clk;
+	}
+
+	ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get, clk_data);
+	if (ret < 0) {
+		dev_err(dev, "Failed to add Qcom CPUFreq clock provider\n");
+		return ret;
 	}
 
 	ret = cpufreq_register_driver(&cpufreq_qcom_hw_driver);
-- 
2.25.1