[v3,13/28] soc: qcom: Add driver for Qualcomm Krait L2 cache scaling

diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
index e597799e8121..01090b7a3c06 100644
--- a/drivers/soc/qcom/Kconfig
+++ b/drivers/soc/qcom/Kconfig
@@ -70,6 +70,15 @@  config QCOM_LLCC
 	  SDM845. This provides interfaces to clients that use the LLCC.
 	  Say yes here to enable LLCC slice driver.
 
+config QCOM_KRAIT_L2_CACHE
+	tristate "Qualcomm Krait L2 cache scaling"
+	depends on ARCH_QCOM && ARM || COMPILE_TEST
+	select INTERCONNECT
+	select INTERCONNECT_CLK
+	default ARM_QCOM_CPUFREQ_NVMEM
+	help
+	  The driver for scaling the L2 cache frequency on Qualcomm Krait platforms.
+
 config QCOM_KRYO_L2_ACCESSORS
 	bool
 	depends on (ARCH_QCOM || COMPILE_TEST) && ARM64
diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
index 99114c71092b..cdd1cc96e9f9 100644
--- a/drivers/soc/qcom/Makefile
+++ b/drivers/soc/qcom/Makefile
@@ -31,6 +31,7 @@  obj-$(CONFIG_QCOM_APR) += apr.o
 obj-$(CONFIG_QCOM_LLCC) += llcc-qcom.o
 obj-$(CONFIG_QCOM_RPMHPD) += rpmhpd.o
 obj-$(CONFIG_QCOM_RPMPD) += rpmpd.o
+obj-$(CONFIG_QCOM_KRAIT_L2_CACHE) += krait-l2-cache.o
 obj-$(CONFIG_QCOM_KRYO_L2_ACCESSORS) +=	kryo-l2-accessors.o
 obj-$(CONFIG_QCOM_ICC_BWMON)	+= icc-bwmon.o
 qcom_ice-objs			+= ice.o
diff --git a/drivers/soc/qcom/krait-l2-cache.c b/drivers/soc/qcom/krait-l2-cache.c
new file mode 100644
index 000000000000..c493da50ab65
--- /dev/null
+++ b/drivers/soc/qcom/krait-l2-cache.c
@@ -0,0 +1,167 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2023, Linaro Ltd.
+ */
+
+#include <linux/clk.h>
+#include <linux/interconnect-clk.h>
+#include <linux/interconnect-provider.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_opp.h>
+#include <linux/regulator/consumer.h>
+
+#include <dt-bindings/soc/qcom,krait-l2-cache.h>
+
+/* Random ID that doesn't clash with main qnoc and OSM */
+#define L2_MASTER_NODE 2000
+
+static int krait_l2_set_one_supply(struct device *dev,
+				   struct regulator *reg,
+				   struct dev_pm_opp_supply *supply)
+{
+	int ret;
+
+	dev_dbg(dev, "%s: voltages (mV): %lu %lu %lu\n", __func__,
+		supply->u_volt_min, supply->u_volt, supply->u_volt_max);
+
+	ret = regulator_set_voltage_triplet(reg,
+					    supply->u_volt_min,
+					    supply->u_volt,
+					    supply->u_volt_max);
+	if (ret) {
+		dev_err(dev, "%s: failed to set voltage (%lu %lu %lu mV): %d\n",
+			__func__, supply->u_volt_min, supply->u_volt,
+			supply->u_volt_max, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+/* vdd-mem and vdd-dig */
+#define NUM_SUPPLIES 2
+static int krait_l2_config_regulators(struct device *dev,
+				      struct dev_pm_opp *old_opp,
+				      struct dev_pm_opp *new_opp,
+				      struct regulator **regulators,
+				      unsigned int count)
+{
+	struct dev_pm_opp_supply supplies[NUM_SUPPLIES];
+	unsigned long old_freq, freq;
+	unsigned int i;
+	int ret;
+
+	if (WARN_ON_ONCE(count != NUM_SUPPLIES))
+		return -EINVAL;
+
+	ret = dev_pm_opp_get_supplies(new_opp, supplies);
+	if (WARN_ON(ret))
+		return ret;
+
+	old_freq = dev_pm_opp_get_freq(old_opp);
+	freq = dev_pm_opp_get_freq(new_opp);
+
+	WARN_ON(!old_freq || !freq);
+	if (freq > old_freq) {
+		for (i = 0; i < count; i++) {
+			ret = krait_l2_set_one_supply(dev, regulators[i], &supplies[i]);
+			if (ret)
+				goto restore_backwards;
+		}
+	} else {
+		for (i = count; i > 0; i--) {
+			ret = krait_l2_set_one_supply(dev, regulators[i - 1], &supplies[i - 1]);
+			if (ret)
+				goto restore_forward;
+		}
+	}
+
+	return 0;
+
+restore_backwards:
+
+	dev_pm_opp_get_supplies(old_opp, supplies);
+
+	for (; i > 0; i--)
+		krait_l2_set_one_supply(dev, regulators[i - 1], &supplies[i - 1]);
+
+	return ret;
+
+restore_forward:
+
+	dev_pm_opp_get_supplies(old_opp, supplies);
+
+	for ( ; i < count; i++)
+		krait_l2_set_one_supply(dev, regulators[i], &supplies[i]);
+
+	return ret;
+}
+
+static int krait_l2_probe(struct platform_device *pdev)
+{
+	struct dev_pm_opp_config krait_l2_cfg = {
+		.clk_names = (const char * const[]) { NULL, NULL },
+		.config_regulators = krait_l2_config_regulators,
+		.regulator_names = (const char * const[]) { "vdd-mem", "vdd-dig", NULL },
+	};
+	struct icc_clk_data data[] = {
+		{ .name = "l2", .opp = true},
+	};
+
+	struct device *dev = &pdev->dev;
+	struct icc_provider *provider;
+	struct clk *clk;
+	int ret;
+
+	clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	ret = devm_pm_opp_set_config(dev, &krait_l2_cfg);
+	if (ret)
+		return ret;
+
+	ret = devm_pm_opp_of_add_table(dev);
+	if (ret)
+		return ret;
+
+	data[0].clk = clk;
+	provider = icc_clk_register(dev, L2_MASTER_NODE, ARRAY_SIZE(data), data);
+	if (IS_ERR(provider))
+		return PTR_ERR(provider);
+
+	platform_set_drvdata(pdev, provider);
+
+	return 0;
+}
+
+static int krait_l2_remove(struct platform_device *pdev)
+{
+	struct icc_provider *provider = platform_get_drvdata(pdev);
+
+	icc_clk_unregister(provider);
+
+	return 0;
+}
+
+static const struct of_device_id krait_l2_match_table[] = {
+	{ .compatible = "qcom,krait-l2-cache" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, krait_l2_match_table);
+
+static struct platform_driver krait_l2_driver = {
+	.probe = krait_l2_probe,
+	.remove = krait_l2_remove,
+	.driver = {
+		.name = "qcom-krait-l2",
+		.of_match_table = krait_l2_match_table,
+		.sync_state = icc_sync_state,
+	},
+};
+
+module_platform_driver(krait_l2_driver);
+
+MODULE_DESCRIPTION("Qualcomm Krait L2 scaling driver");
+MODULE_LICENSE("GPL v2");