Date:   Tue, 15 May 2018 13:51:10 +0800
From:   Anson Huang <Anson.Huang@....com>
To:     rjw@...ysocki.net, viresh.kumar@...aro.org
Cc:     Linux-imx@....com, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: [PATCH] cpufreq: add imx8mq-cpufreq driver

Add imx8mq-cpufreq driver for NXP i.MX8MQ SoC to support the
hardware specific frequency and voltage scaling requirements.

Signed-off-by: Anson Huang <Anson.Huang@....com>
---
 drivers/cpufreq/Kconfig.arm      |   8 ++
 drivers/cpufreq/Makefile         |   1 +
 drivers/cpufreq/imx8mq-cpufreq.c | 234 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 243 insertions(+)
 create mode 100644 drivers/cpufreq/imx8mq-cpufreq.c

diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index 96b35b8..ea8e2b6 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -105,6 +105,14 @@ config ARM_IMX6Q_CPUFREQ
 
 	  If in doubt, say N.
 
+config ARM_IMX8MQ_CPUFREQ
+	tristate "NXP i.MX8MQ cpufreq support"
+	select PM_OPP
+	help
+	  This adds cpufreq driver support for NXP i.MX8MQ SoC.
+
+	  If in doubt, say N.
+
 config ARM_KIRKWOOD_CPUFREQ
 	def_bool MACH_KIRKWOOD
 	help
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index 8d24ade..a3bc61c 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -59,6 +59,7 @@ obj-$(CONFIG_ARCH_DAVINCI)		+= davinci-cpufreq.o
 obj-$(CONFIG_ARM_EXYNOS5440_CPUFREQ)	+= exynos5440-cpufreq.o
 obj-$(CONFIG_ARM_HIGHBANK_CPUFREQ)	+= highbank-cpufreq.o
 obj-$(CONFIG_ARM_IMX6Q_CPUFREQ)		+= imx6q-cpufreq.o
+obj-$(CONFIG_ARM_IMX8MQ_CPUFREQ)	+= imx8mq-cpufreq.o
 obj-$(CONFIG_ARM_KIRKWOOD_CPUFREQ)	+= kirkwood-cpufreq.o
 obj-$(CONFIG_ARM_MEDIATEK_CPUFREQ)	+= mediatek-cpufreq.o
 obj-$(CONFIG_MACH_MVEBU_V7)		+= mvebu-cpufreq.o
diff --git a/drivers/cpufreq/imx8mq-cpufreq.c b/drivers/cpufreq/imx8mq-cpufreq.c
new file mode 100644
index 0000000..2aee6049
--- /dev/null
+++ b/drivers/cpufreq/imx8mq-cpufreq.c
@@ -0,0 +1,234 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2018 NXP
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/clk.h>
+#include <linux/cpu.h>
+#include <linux/cpufreq.h>
+#include <linux/cpu_cooling.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/pm_opp.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+#include <linux/suspend.h>
+
+static struct device *cpu_dev;
+static bool free_opp;
+static struct cpufreq_frequency_table *freq_table;
+static unsigned int transition_latency;
+static struct thermal_cooling_device *cdev;
+static struct regulator *arm_reg;
+static unsigned int max_freq;
+
+#define IMX8MQ_CPUFREQ_CLK_NUM		5
+
+enum IMX8MQ_CPUFREQ_CLKS {
+	A53,
+	A53_SRC,
+	ARM_PLL,
+	ARM_PLL_OUT,
+	SYS1_PLL_800M,
+};
+
+static struct clk_bulk_data clks[] = {
+	{ .id = "a53" },
+	{ .id = "a53_src" },
+	{ .id = "arm_pll" },
+	{ .id = "arm_pll_out" },
+	{ .id = "sys1_pll_800m" },
+};
+
+static int imx8mq_set_target(struct cpufreq_policy *policy, unsigned int index)
+{
+	struct dev_pm_opp *opp;
+	unsigned long freq_hz, volt;
+	unsigned int old_freq, new_freq;
+	int ret;
+
+	new_freq = freq_table[index].frequency;
+	freq_hz = new_freq * 1000;
+	old_freq = policy->cur;
+
+	opp = dev_pm_opp_find_freq_ceil(cpu_dev, &freq_hz);
+	if (IS_ERR(opp)) {
+		dev_err(cpu_dev, "failed to find OPP for %ld\n", freq_hz);
+		return PTR_ERR(opp);
+	}
+	volt = dev_pm_opp_get_voltage(opp);
+	dev_pm_opp_put(opp);
+
+	dev_dbg(cpu_dev, "%u MHz --> %u MHz\n",
+		old_freq / 1000, new_freq / 1000);
+
+	if (new_freq > old_freq) {
+		ret = regulator_set_voltage_tol(arm_reg, volt, 0);
+		if (ret) {
+			dev_err(cpu_dev, "failed to scale arm_reg up: %d\n",
+				ret);
+			return ret;
+		}
+	}
+
+	clk_set_parent(clks[A53_SRC].clk, clks[SYS1_PLL_800M].clk);
+	clk_set_rate(clks[ARM_PLL].clk, new_freq * 1000);
+	clk_set_parent(clks[A53_SRC].clk, clks[ARM_PLL_OUT].clk);
+
+	/* Ensure the arm clock divider is what we expect */
+	ret = clk_set_rate(clks[A53].clk, new_freq * 1000);
+	if (ret)
+		dev_err(cpu_dev, "failed to set clock rate: %d\n", ret);
+
+	if (new_freq < old_freq) {
+		ret = regulator_set_voltage_tol(arm_reg, volt, 0);
+		if (ret) {
+			dev_err(cpu_dev, "failed to scale arm_reg down: %d\n",
+				ret);
+			return ret;
+		}
+	}
+
+	return ret;
+}
+
+static void imx8mq_cpufreq_ready(struct cpufreq_policy *policy)
+{
+	cdev = of_cpufreq_cooling_register(policy);
+}
+
+static int imx8mq_cpufreq_init(struct cpufreq_policy *policy)
+{
+	int ret;
+
+	policy->clk = clks[A53].clk;
+	ret = cpufreq_generic_init(policy, freq_table, transition_latency);
+	policy->suspend_freq = max_freq;
+
+	return ret;
+}
+
+static struct cpufreq_driver imx8mq_cpufreq_driver = {
+	.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+	.verify = cpufreq_generic_frequency_table_verify,
+	.target_index = imx8mq_set_target,
+	.get = cpufreq_generic_get,
+	.init = imx8mq_cpufreq_init,
+	.name = "imx8mq-cpufreq",
+	.ready = imx8mq_cpufreq_ready,
+	.attr = cpufreq_generic_attr,
+	.suspend = cpufreq_generic_suspend,
+};
+
+static int imx8mq_cpufreq_probe(struct platform_device *pdev)
+{
+	struct device_node *np;
+	int ret, num;
+
+	cpu_dev = get_cpu_device(0);
+	if (!cpu_dev) {
+		pr_err("failed to get cpu0 device\n");
+		return -ENODEV;
+	}
+
+	np = of_node_get(cpu_dev->of_node);
+	if (!np) {
+		dev_err(cpu_dev, "failed to find cpu0 node\n");
+		return -ENOENT;
+	}
+
+	ret = clk_bulk_get(cpu_dev, IMX8MQ_CPUFREQ_CLK_NUM, clks);
+	if (ret)
+		goto put_node;
+
+	arm_reg = regulator_get(cpu_dev, "arm");
+	if (PTR_ERR(arm_reg) == -EPROBE_DEFER) {
+		ret = -EPROBE_DEFER;
+		dev_dbg(cpu_dev, "regulator not ready, defer\n");
+		goto put_reg;
+	}
+	if (IS_ERR(arm_reg)) {
+		dev_err(cpu_dev, "failed to get regulator\n");
+		ret = -ENOENT;
+		goto put_reg;
+	}
+
+	/*
+	 * We expect an OPP table supplied by platform.
+	 * Just, in case the platform did not supply the OPP
+	 * table, it will try to get it.
+	 */
+	num = dev_pm_opp_get_opp_count(cpu_dev);
+	if (num < 0) {
+		ret = dev_pm_opp_of_add_table(cpu_dev);
+		if (ret < 0) {
+			dev_err(cpu_dev, "failed to init OPP table: %d\n", ret);
+			goto put_clk;
+		}
+	}
+	free_opp = true;
+
+	ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
+	if (ret) {
+		dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
+		goto out_free_opp;
+	}
+	max_freq = freq_table[--num].frequency;
+
+	if (of_property_read_u32(np, "clock-latency", &transition_latency))
+		transition_latency = CPUFREQ_ETERNAL;
+
+	ret = cpufreq_register_driver(&imx8mq_cpufreq_driver);
+	if (ret) {
+		dev_err(cpu_dev, "failed register driver: %d\n", ret);
+		goto free_freq_table;
+	}
+
+	of_node_put(np);
+	return 0;
+
+free_freq_table:
+	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
+out_free_opp:
+	dev_pm_opp_of_remove_table(cpu_dev);
+put_clk:
+	clk_bulk_put(IMX8MQ_CPUFREQ_CLK_NUM, clks);
+put_reg:
+	if (!IS_ERR(arm_reg))
+		regulator_put(arm_reg);
+put_node:
+	of_node_put(np);
+	return ret;
+}
+
+static int imx8mq_cpufreq_remove(struct platform_device *pdev)
+{
+	cpufreq_cooling_unregister(cdev);
+	cpufreq_unregister_driver(&imx8mq_cpufreq_driver);
+	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
+	if (free_opp)
+		dev_pm_opp_of_remove_table(cpu_dev);
+	regulator_put(arm_reg);
+	clk_bulk_put(IMX8MQ_CPUFREQ_CLK_NUM, clks);
+
+	return 0;
+}
+
+static struct platform_driver imx8mq_cpufreq_platdrv = {
+	.driver = {
+		.name	= "imx8mq-cpufreq",
+	},
+	.probe		= imx8mq_cpufreq_probe,
+	.remove		= imx8mq_cpufreq_remove,
+};
+module_platform_driver(imx8mq_cpufreq_platdrv);
+
+MODULE_AUTHOR("Anson Huang <Anson.Huang@....com>");
+MODULE_DESCRIPTION("Freescale i.MX8MQ cpufreq driver");
+MODULE_LICENSE("GPL");
-- 
2.7.4

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