soc: samsung: Add Exynos Adaptive Supply Voltage driver

The Adaptive Supply Voltage (ASV) driver adjusts CPU cluster operating
points depending on exact revision of an SoC retrieved from the CHIPID
block or the OTP memory.  This allows for some power saving as for some
CPU clock frequencies we can lower CPU cluster's supply voltage comparing
to safe values common to all the SoC revisions.

This patch adds support for Exynos5422/5800 SoC, it is partially based
on code from https://github.com/hardkernel/linux repository,
branch odroidxu4-4.14.y, files: arch/arm/mach-exynos/exynos5422-asv.[ch].

Tested on Odroid XU3, XU4, XU3 Lite.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

1 files changed, 177 insertions, 0 deletions

diff --git a/drivers/soc/samsung/exynos-asv.c b/drivers/soc/samsung/exynos-asv.c
new file mode 100644
index 000000000000..8abf4dfaa5c5
--- /dev/null
+++ b/drivers/soc/samsung/exynos-asv.c
@@ -0,0 +1,177 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019 Samsung Electronics Co., Ltd.
+ *	      http://www.samsung.com/
+ * Author: Sylwester Nawrocki <s.nawrocki@samsung.com>
+ *
+ * Samsung Exynos SoC Adaptive Supply Voltage support
+ */
+
+#include <linux/cpu.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_opp.h>
+#include <linux/regmap.h>
+#include <linux/soc/samsung/exynos-chipid.h>
+
+#include "exynos-asv.h"
+#include "exynos5422-asv.h"
+
+#define MHZ 1000000U
+
+static int exynos_asv_update_cpu_opps(struct exynos_asv *asv,
+				      struct device *cpu)
+{
+	struct exynos_asv_subsys *subsys = NULL;
+	struct dev_pm_opp *opp;
+	unsigned int opp_freq;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(asv->subsys); i++) {
+		if (of_device_is_compatible(cpu->of_node,
+					    asv->subsys[i].cpu_dt_compat)) {
+			subsys = &asv->subsys[i];
+			break;
+		}
+	}
+	if (!subsys)
+		return -EINVAL;
+
+	for (i = 0; i < subsys->table.num_rows; i++) {
+		unsigned int new_volt, volt;
+		int ret;
+
+		opp_freq = exynos_asv_opp_get_frequency(subsys, i);
+
+		opp = dev_pm_opp_find_freq_exact(cpu, opp_freq * MHZ, true);
+		if (IS_ERR(opp)) {
+			dev_info(asv->dev, "cpu%d opp%d, freq: %u missing\n",
+				 cpu->id, i, opp_freq);
+
+			continue;
+		}
+
+		volt = dev_pm_opp_get_voltage(opp);
+		new_volt = asv->opp_get_voltage(subsys, i, volt);
+		dev_pm_opp_put(opp);
+
+		if (new_volt == volt)
+			continue;
+
+		ret = dev_pm_opp_adjust_voltage(cpu, opp_freq * MHZ,
+						new_volt, new_volt, new_volt);
+		if (ret < 0)
+			dev_err(asv->dev,
+				"Failed to adjust OPP %u Hz/%u uV for cpu%d\n",
+				opp_freq, new_volt, cpu->id);
+		else
+			dev_dbg(asv->dev,
+				"Adjusted OPP %u Hz/%u -> %u uV, cpu%d\n",
+				opp_freq, volt, new_volt, cpu->id);
+	}
+
+	return 0;
+}
+
+static int exynos_asv_update_opps(struct exynos_asv *asv)
+{
+	struct opp_table *last_opp_table = NULL;
+	struct device *cpu;
+	int ret, cpuid;
+
+	for_each_possible_cpu(cpuid) {
+		struct opp_table *opp_table;
+
+		cpu = get_cpu_device(cpuid);
+		if (!cpu)
+			continue;
+
+		opp_table = dev_pm_opp_get_opp_table(cpu);
+		if (IS_ERR(opp_table))
+			continue;
+
+		if (!last_opp_table || opp_table != last_opp_table) {
+			last_opp_table = opp_table;
+
+			ret = exynos_asv_update_cpu_opps(asv, cpu);
+			if (ret < 0)
+				dev_err(asv->dev, "Couldn't udate OPPs for cpu%d\n",
+					cpuid);
+		}
+
+		dev_pm_opp_put_opp_table(opp_table);
+	}
+
+	return	0;
+}
+
+static int exynos_asv_probe(struct platform_device *pdev)
+{
+	int (*probe_func)(struct exynos_asv *asv);
+	struct exynos_asv *asv;
+	struct device *cpu_dev;
+	u32 product_id = 0;
+	int ret, i;
+
+	cpu_dev = get_cpu_device(0);
+	ret = dev_pm_opp_get_opp_count(cpu_dev);
+	if (ret < 0)
+		return -EPROBE_DEFER;
+
+	asv = devm_kzalloc(&pdev->dev, sizeof(*asv), GFP_KERNEL);
+	if (!asv)
+		return -ENOMEM;
+
+	asv->chipid_regmap = device_node_to_regmap(pdev->dev.of_node);
+	if (IS_ERR(asv->chipid_regmap)) {
+		dev_err(&pdev->dev, "Could not find syscon regmap\n");
+		return PTR_ERR(asv->chipid_regmap);
+	}
+
+	regmap_read(asv->chipid_regmap, EXYNOS_CHIPID_REG_PRO_ID, &product_id);
+
+	switch (product_id & EXYNOS_MASK) {
+	case 0xE5422000:
+		probe_func = exynos5422_asv_init;
+		break;
+	default:
+		return -ENODEV;
+	}
+
+	ret = of_property_read_u32(pdev->dev.of_node, "samsung,asv-bin",
+				   &asv->of_bin);
+	if (ret < 0)
+		asv->of_bin = -EINVAL;
+
+	asv->dev = &pdev->dev;
+	dev_set_drvdata(&pdev->dev, asv);
+
+	for (i = 0; i < ARRAY_SIZE(asv->subsys); i++)
+		asv->subsys[i].asv = asv;
+
+	ret = probe_func(asv);
+	if (ret < 0)
+		return ret;
+
+	return exynos_asv_update_opps(asv);
+}
+
+static const struct of_device_id exynos_asv_of_device_ids[] = {
+	{ .compatible = "samsung,exynos4210-chipid" },
+	{}
+};
+
+static struct platform_driver exynos_asv_driver = {
+	.driver = {
+		.name = "exynos-asv",
+		.of_match_table = exynos_asv_of_device_ids,
+	},
+	.probe	= exynos_asv_probe,
+};
+module_platform_driver(exynos_asv_driver);