[PATCH] cpufreq: imx: Add cpufreq driver for imx7D/Solo SOC

[Bai Ping]

The i.MX7Dual/Solo is a new series of the i.MX SOC family.
The existing cpufreq driver for 'i.MX6' or 'cpufreq-dt' can
NOT match the requirement of this new SOC. This patch adds the
cpufreq driver for i.MX7Dual/Solo.

Signed-off-by: Bai Ping <b51503@xxxxxxxxxxxxx>
---
 drivers/cpufreq/Kconfig.arm     |  10 ++
 drivers/cpufreq/Makefile        |   1 +
 drivers/cpufreq/imx7d-cpufreq.c | 257 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 268 insertions(+)
 create mode 100644 drivers/cpufreq/imx7d-cpufreq.c

diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index 8014c23..adddfd7 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -67,6 +67,16 @@ config ARM_IMX6Q_CPUFREQ
 
 	  If in doubt, say N.
 
+config ARM_IMX7D_CPUFREQ
+	tristate "Freescale i.MX7 cpufreq support"
+	depends on ARCH_MXC
+	select PM_OPP
+	help
+	  This adds cpufreq driver support for Freescale i.MX7Dual/Solo
+	  series SoCs.
+
+	  If in doubt, say N.
+
 config ARM_INTEGRATOR
 	tristate "CPUfreq driver for ARM Integrator CPUs"
 	depends on ARCH_INTEGRATOR
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index c0af1a1..66723a0 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -55,6 +55,7 @@ obj-$(CONFIG_ARM_EXYNOS5440_CPUFREQ)	+= exynos5440-cpufreq.o
 obj-$(CONFIG_ARM_HIGHBANK_CPUFREQ)	+= highbank-cpufreq.o
 obj-$(CONFIG_ARM_HISI_ACPU_CPUFREQ)	+= hisi-acpu-cpufreq.o
 obj-$(CONFIG_ARM_IMX6Q_CPUFREQ)		+= imx6q-cpufreq.o
+obj-$(CONFIG_ARM_IMX7D_CPUFREQ)		+= imx7d-cpufreq.o
 obj-$(CONFIG_ARM_INTEGRATOR)		+= integrator-cpufreq.o
 obj-$(CONFIG_ARM_KIRKWOOD_CPUFREQ)	+= kirkwood-cpufreq.o
 obj-$(CONFIG_ARM_MT8173_CPUFREQ)	+= mt8173-cpufreq.o
diff --git a/drivers/cpufreq/imx7d-cpufreq.c b/drivers/cpufreq/imx7d-cpufreq.c
new file mode 100644
index 0000000..7506702
--- /dev/null
+++ b/drivers/cpufreq/imx7d-cpufreq.c
@@ -0,0 +1,257 @@
+/*
+ * Copyright (C) 2015 Freescale Semiconductor, Inc.
+ *
+ * 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/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>
+
+static struct clk *arm_clk;
+static struct clk *pll_arm;
+static struct clk *arm_src;
+static struct clk *pll_sys_main;
+
+static struct regulator *arm_reg;
+
+static struct device *cpu_dev;
+static bool free_opp;
+static struct cpufreq_frequency_table *freq_table;
+static unsigned int transition_latency;
+
+static int imx7d_set_target(struct cpufreq_policy *policy, unsigned int index)
+{
+	struct dev_pm_opp *opp;
+	unsigned long freq_hz, volt, volt_old;
+	unsigned int old_freq, new_freq;
+	int ret;
+
+	new_freq = freq_table[index].frequency;
+	freq_hz = new_freq * 1000;
+	old_freq = clk_get_rate(arm_clk) / 1000;
+
+	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);
+		return PTR_ERR(opp);
+	}
+	volt = dev_pm_opp_get_voltage(opp);
+	rcu_read_unlock();
+	volt_old = regulator_get_voltage(arm_reg);
+
+	dev_dbg(cpu_dev, "%u MHz, %ld mV --> %u MHz, %ld mV\n",
+		old_freq / 1000, volt_old / 1000,
+		new_freq / 1000, volt / 1000);
+
+	/* Scaling up? scale voltage before frequency */
+	if (new_freq > old_freq) {
+		ret = regulator_set_voltage_tol(arm_reg, volt, 0);
+		if (ret) {
+			dev_err(cpu_dev, "failed to scale vddarm up: %d\n", ret);
+			return ret;
+		}
+	}
+
+	/* before changing pll_arm rate, change the arm_src's soure
+	 * to pll_sys_main clk first.
+	 */
+	clk_set_parent(arm_src, pll_sys_main);
+	clk_set_rate(pll_arm, new_freq * 1000);
+	clk_set_parent(arm_src, pll_arm);
+
+	/* change the cpu frequency */
+	ret = clk_set_rate(arm_clk, new_freq * 1000);
+	if (ret) {
+		dev_err(cpu_dev, " failed to set clock rate: %d\n", ret);
+		regulator_set_voltage_tol(arm_reg, volt_old, 0);
+		return ret;
+	}
+
+	/* scaling down? scaling voltage after frequency */
+	if (new_freq < old_freq) {
+		ret = regulator_set_voltage_tol(arm_reg, volt, 0);
+		if (ret) {
+			dev_warn(cpu_dev, "failed to scale vddarm down: %d\n", ret);
+			ret = 0;
+		}
+	}
+
+	return 0;
+}
+
+static int imx7d_cpufreq_init(struct cpufreq_policy *policy)
+{
+	policy->clk = arm_clk;
+	policy->cur = clk_get_rate(arm_clk) / 1000;
+
+	return  cpufreq_generic_init(policy, freq_table, transition_latency);
+}
+
+static struct cpufreq_driver imx7d_cpufreq_driver = {
+	.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+	.verify = cpufreq_generic_frequency_table_verify,
+	.target_index = imx7d_set_target,
+	.get = cpufreq_generic_get,
+	.init = imx7d_cpufreq_init,
+	.name = "imx7d-cpufreq",
+	.attr = cpufreq_generic_attr,
+};
+
+static int imx7d_cpufreq_probe(struct platform_device *pdev)
+{
+	struct device_node *np;
+	struct dev_pm_opp *opp;
+	unsigned long min_volt, max_volt;
+	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 the cpu0 node\n");
+		return -ENOENT;
+	}
+
+	arm_clk = clk_get(cpu_dev, "arm");
+	arm_src	= clk_get(cpu_dev, "arm_root_src");
+	pll_arm = clk_get(cpu_dev, "pll_arm");
+	pll_sys_main = clk_get(cpu_dev, "pll_sys_main");
+
+	if (IS_ERR(arm_clk) || IS_ERR(arm_src) || IS_ERR(pll_arm) ||
+	    IS_ERR(pll_sys_main)) {
+		dev_err(cpu_dev, "failed to get clocks\n");
+		ret = -ENOENT;
+		goto put_clk;
+	}
+
+	arm_reg = devm_regulator_get(cpu_dev, "arm");
+	if (IS_ERR(arm_reg)) {
+		ret = PTR_ERR(arm_reg);
+		if (ret != -EPROBE_DEFER)
+			dev_err(cpu_dev, "failed to get the regulator\n");
+
+		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_reg;
+		}
+
+		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;
+	}
+
+	if (of_property_read_u32(np, "clock-latency", &transition_latency))
+		transition_latency = CPUFREQ_ETERNAL;
+
+	/* OPP is maintained in order of increasing frequency, and
+	 * freq_table initialized from OPP is therefore sorted in the
+	 * same order
+	 */
+	rcu_read_lock();
+	opp = dev_pm_opp_find_freq_exact(cpu_dev,
+				freq_table[0].frequency * 1000, true);
+	min_volt = dev_pm_opp_get_voltage(opp);
+	opp = dev_pm_opp_find_freq_exact(cpu_dev,
+				freq_table[--num].frequency * 1000, true);
+	max_volt = dev_pm_opp_get_voltage(opp);
+	rcu_read_unlock();
+	ret = regulator_set_voltage_time(arm_reg, min_volt, max_volt);
+	if (ret > 0)
+		transition_latency += ret * 1000;
+
+	ret = cpufreq_register_driver(&imx7d_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:
+	if (free_opp)
+		dev_pm_opp_of_remove_table(cpu_dev);
+put_reg:
+	if (!IS_ERR(arm_reg))
+		regulator_put(arm_reg);
+put_clk:
+	if (!IS_ERR(arm_clk))
+		clk_put(arm_clk);
+	if (!IS_ERR(arm_src))
+		clk_put(arm_src);
+	if (!IS_ERR(pll_arm))
+		clk_put(pll_arm);
+	if (!IS_ERR(pll_sys_main))
+		clk_put(pll_sys_main);
+	of_node_put(np);
+
+	return ret;
+}
+
+static int imx7d_cpufreq_remove(struct platform_device *pdev)
+{
+	cpufreq_unregister_driver(&imx7d_cpufreq_driver);
+	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
+	dev_pm_opp_of_remove_table(cpu_dev);
+
+	regulator_put(arm_reg);
+
+	clk_put(arm_clk);
+	clk_put(arm_src);
+	clk_put(pll_arm);
+	clk_put(pll_sys_main);
+
+	return 0;
+}
+
+static struct platform_driver imx7d_cpufreq_platdrv = {
+	.driver = {
+		.name	= "imx7d-cpufreq",
+		.owner	= THIS_MODULE,
+	},
+	.probe		= imx7d_cpufreq_probe,
+	.remove		= imx7d_cpufreq_remove,
+};
+
+module_platform_driver(imx7d_cpufreq_platdrv);
+
+MODULE_DESCRIPTION("Freescale i.MX7D cpufreq driver");
+MODULE_LICENSE("GPL");
-- 
1.9.1

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