[PATCH 1/2] cpufreq: Add i.mx8mq support

[Abel Vesa]

From: Anson Huang <Anson.Huang@xxxxxxx>

Add i.MX8MQ cpufreq support, current version of
EVK board does NOT support voltage scale, but next
version will add this support, so this driver only
supports cpu frequency scale, voltage scale will
be added later once new board available.

A53 CPU clock normally is from ARM_PLL, but during
ARM_PLL relock window, it will be switched to
SYS1_PLL_800M to avoid clock missing, and after
arm pll relock done, it will be switched back.

Signed-off-by: Anson Huang <anson.huang@xxxxxxx>
Signed-off-by: Abel Vesa <abel.vesa@xxxxxxx>
---
 drivers/cpufreq/Kconfig.arm      |   8 ++
 drivers/cpufreq/Makefile         |   1 +
 drivers/cpufreq/imx8mq-cpufreq.c | 223 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 232 insertions(+)
 create mode 100644 drivers/cpufreq/imx8mq-cpufreq.c

diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index 179a1d3..9d8001c 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -92,6 +92,14 @@ 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 series SoCs.
+
+	  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 689b26c..fe5416c 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -56,6 +56,7 @@ obj-$(CONFIG_ACPI_CPPC_CPUFREQ)		+= cppc_cpufreq.o
 obj-$(CONFIG_ARCH_DAVINCI)		+= davinci-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..ee24fab
--- /dev/null
+++ b/drivers/cpufreq/imx8mq-cpufreq.c
@@ -0,0 +1,223 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 NXP
+ */
+
+#include <linux/clk.h>
+#include <linux/cpu.h>
+#include <linux/cpufreq.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/pm_opp.h>
+#include <linux/platform_device.h>
+#include <linux/suspend.h>
+
+static struct device *cpu_dev;
+static bool free_opp;
+static struct cpufreq_frequency_table *freq_table;
+static struct mutex set_cpufreq_lock;
+static unsigned int transition_latency;
+static unsigned int suspend_freq;
+static struct clk *a53_clk;
+static struct clk *arm_a53_src_clk;
+static struct clk *arm_pll_clk;
+static struct clk *arm_pll_out_clk;
+static struct clk *sys1_pll_800m_clk;
+
+static int imx8mq_set_target(struct cpufreq_policy *policy, unsigned int index)
+{
+	struct dev_pm_opp *opp;
+	unsigned long freq_hz;
+	unsigned int old_freq, new_freq;
+	int ret;
+
+	mutex_lock(&set_cpufreq_lock);
+
+	new_freq = freq_table[index].frequency;
+	freq_hz = new_freq * 1000;
+	old_freq = policy->cur;
+
+	rcu_read_lock();
+	opp = dev_pm_opp_find_freq_ceil(cpu_dev, &freq_hz);
+	if (IS_ERR(opp)) {
+		rcu_read_unlock();
+		dev_err(cpu_dev, "failed to find OPP for %ld\n", freq_hz);
+		mutex_unlock(&set_cpufreq_lock);
+		return PTR_ERR(opp);
+	}
+	rcu_read_unlock();
+
+	dev_dbg(cpu_dev, "%u MHz --> %u MHz\n",
+		old_freq / 1000, new_freq / 1000);
+
+	clk_set_parent(arm_a53_src_clk, sys1_pll_800m_clk);
+	clk_set_rate(arm_pll_clk, new_freq * 1000);
+	clk_set_parent(arm_a53_src_clk, arm_pll_out_clk);
+
+	/* Ensure the arm clock divider is what we expect */
+	ret = clk_set_rate(a53_clk, new_freq * 1000);
+	if (ret)
+		dev_err(cpu_dev, "failed to set clock rate: %d\n", ret);
+
+	mutex_unlock(&set_cpufreq_lock);
+	return ret;
+}
+
+static int imx8mq_cpufreq_init(struct cpufreq_policy *policy)
+{
+	int ret;
+
+	policy->clk = a53_clk;
+	policy->cur = clk_get_rate(a53_clk) / 1000;
+	policy->suspend_freq = suspend_freq;
+
+	ret = cpufreq_generic_init(policy, freq_table, transition_latency);
+	if (ret) {
+		dev_err(cpu_dev, "imx8mq cpufreq init failed!\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+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",
+	.attr = cpufreq_generic_attr,
+#ifdef CONFIG_PM
+	.suspend = cpufreq_generic_suspend,
+#endif
+};
+
+static int imx8mq_cpufreq_probe(struct platform_device *pdev)
+{
+	struct device_node *np;
+	int num, ret;
+
+	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;
+	}
+
+	a53_clk = clk_get(cpu_dev, "a53");
+	arm_a53_src_clk = clk_get(cpu_dev, "arm_a53_src");
+	arm_pll_clk = clk_get(cpu_dev, "arm_pll");
+	arm_pll_out_clk = clk_get(cpu_dev, "arm_pll_out");
+	sys1_pll_800m_clk = clk_get(cpu_dev, "sys1_pll_800m");
+	if (IS_ERR(a53_clk) || IS_ERR(arm_a53_src_clk)
+		|| IS_ERR(arm_pll_out_clk) || IS_ERR(arm_pll_clk)
+		|| IS_ERR(sys1_pll_800m_clk)) {
+		dev_err(cpu_dev, "failed to get clocks\n");
+		ret = -ENOENT;
+		goto put_clk;
+	}
+
+	/*
+	 * We expect an OPP table supplied by platform.
+	 * Just, incase 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;
+		}
+
+		/* Because we have added the OPPs here, we must free them */
+		free_opp = true;
+
+		num = dev_pm_opp_get_opp_count(cpu_dev);
+		if (num < 0) {
+			ret = num;
+			dev_err(cpu_dev, "no OPP table is found: %d\n", ret);
+			goto out_free_opp;
+		}
+	}
+
+	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;
+	}
+
+	/* use MAX freq to suspend */
+	suspend_freq = freq_table[num - 1].frequency;
+
+	if (of_property_read_u32(np, "clock-latency", &transition_latency))
+		transition_latency = CPUFREQ_ETERNAL;
+
+	mutex_init(&set_cpufreq_lock);
+
+	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);
+	dev_info(cpu_dev, "registered imx8mq-cpufreq\n");
+
+	return 0;
+
+free_freq_table:
+	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
+out_free_opp:
+	if (free_opp)
+		dev_pm_opp_of_remove_table(cpu_dev);
+put_clk:
+	if (!IS_ERR(a53_clk))
+		clk_put(a53_clk);
+	if (!IS_ERR(arm_a53_src_clk))
+		clk_put(arm_a53_src_clk);
+	if (!IS_ERR(arm_pll_clk))
+		clk_put(arm_pll_clk);
+	if (!IS_ERR(arm_pll_out_clk))
+		clk_put(arm_pll_out_clk);
+	if (!IS_ERR(sys1_pll_800m_clk))
+		clk_put(sys1_pll_800m_clk);
+	of_node_put(np);
+	return ret;
+}
+
+static int imx8mq_cpufreq_remove(struct platform_device *pdev)
+{
+	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);
+	clk_put(a53_clk);
+	clk_put(arm_a53_src_clk);
+	clk_put(arm_pll_clk);
+	clk_put(arm_pll_out_clk);
+	clk_put(sys1_pll_800m_clk);
+
+	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@xxxxxxx>");
+MODULE_DESCRIPTION("Freescale i.MX8MQ cpufreq driver");
+MODULE_LICENSE("GPL");
-- 
2.7.4