/*
   * Copyright (C) 2013-2015 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/busfreq-imx6.h>
  #include <linux/clk.h>
  #include <linux/cpu.h>
  #include <linux/cpufreq.h>
  #include <linux/delay.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/suspend.h>
  
  #define PU_SOC_VOLTAGE_NORMAL	1250000
  #define PU_SOC_VOLTAGE_HIGH	1275000
  #define FREQ_1P2_GHZ		1200000000
  #define FREQ_396_MHZ		396000
  
  static struct regulator *arm_reg;
  static struct regulator *pu_reg;
  static struct regulator *soc_reg;
  
  static struct clk *arm_clk;
  static struct clk *pll1_sys_clk;
  static struct clk *pll1_sw_clk;
  static struct clk *step_clk;
  static struct clk *pll2_pfd2_396m_clk;
  static struct clk *pll1_bypass;
  static struct clk *pll1_bypass_src;
  static struct clk *pll1;
  
  static struct device *cpu_dev;
  static struct cpufreq_frequency_table *freq_table;
  static unsigned int transition_latency;
  static struct mutex set_cpufreq_lock;
  static u32 *imx6_soc_volt;
  static u32 soc_opp_count;
  
  static int imx6q_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;
  
  	mutex_lock(&set_cpufreq_lock);
  
  	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
  ", freq_hz);
  		mutex_unlock(&set_cpufreq_lock);
  		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
  ",
  		old_freq / 1000, volt_old / 1000,
  		new_freq / 1000, volt / 1000);
  	/*
  	 * CPU freq is increasing, so need to ensure
  	 * that bus frequency is increased too.
  	 */
  	if (old_freq <= FREQ_396_MHZ && new_freq > FREQ_396_MHZ)
  		request_bus_freq(BUS_FREQ_HIGH);
  
  	/* scaling up?  scale voltage before frequency */
  	if (new_freq > old_freq) {
  		if (!IS_ERR(pu_reg) && regulator_is_enabled(pu_reg)) {
  			ret = regulator_set_voltage_tol(pu_reg,
  				imx6_soc_volt[index], 0);
  			if (ret) {
  				dev_err(cpu_dev,
  					"failed to scale vddpu up: %d
  ", ret);
  				mutex_unlock(&set_cpufreq_lock);
  				return ret;
  			}
  		}
  		ret = regulator_set_voltage_tol(soc_reg, imx6_soc_volt[index], 0);
  		if (ret) {
  			dev_err(cpu_dev, "failed to scale vddsoc up: %d
  ", ret);
  			mutex_unlock(&set_cpufreq_lock);
  			return ret;
  		}
  		ret = regulator_set_voltage_tol(arm_reg, volt, 0);
  		if (ret) {
  			dev_err(cpu_dev,
  				"failed to scale vddarm up: %d
  ", ret);
  			mutex_unlock(&set_cpufreq_lock);
  			return ret;
  		}
  	}
  
  	/*
  	 * The setpoints are selected per PLL/PDF frequencies, so we need to
  	 * reprogram PLL for frequency scaling.  The procedure of reprogramming
  	 * PLL1 is as below.
  	 *
  	 *  - Enable pll2_pfd2_396m_clk and reparent pll1_sw_clk to it
  	 *  - Reprogram pll1_sys_clk and reparent pll1_sw_clk back to it
  	 *  - Disable pll2_pfd2_396m_clk
  	 */
  	clk_set_parent(step_clk, pll2_pfd2_396m_clk);
  	clk_set_parent(pll1_sw_clk, step_clk);
  	if (freq_hz > clk_get_rate(pll2_pfd2_396m_clk)) {
  		clk_set_rate(pll1, new_freq * 1000);
  		/*
  		  * Ensure pll1_bypass is set back to pll1.
  		  */
  		clk_set_parent(pll1_bypass, pll1);
  		clk_set_parent(pll1_sw_clk, pll1_sys_clk);
  	} else
  		/*
  		  * Need to ensure that PLL1 is bypassed and enabled
  		  * before ARM-PODF is set.
  		  */
  		clk_set_parent(pll1_bypass, pll1_bypass_src);
  
  
  	/* Ensure the arm clock divider is what we expect */
  	ret = clk_set_rate(arm_clk, new_freq * 1000);
  	if (ret) {
  		dev_err(cpu_dev, "failed to set clock rate: %d
  ", ret);
  		regulator_set_voltage_tol(arm_reg, volt_old, 0);
  		mutex_unlock(&set_cpufreq_lock);
  		return ret;
  	}
  
  	/* scaling down?  scale 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
  ", ret);
  			ret = 0;
  		}
  		ret = regulator_set_voltage_tol(soc_reg, imx6_soc_volt[index], 0);
  		if (ret) {
  			dev_warn(cpu_dev, "failed to scale vddsoc down: %d
  ", ret);
  			ret = 0;
  		}
  		if (!IS_ERR(pu_reg) && regulator_is_enabled(pu_reg)) {
  			ret = regulator_set_voltage_tol(pu_reg,
  				imx6_soc_volt[index], 0);
  			if (ret) {
  				dev_warn(cpu_dev,
  					"failed to scale vddpu down: %d
  ",
  					ret);
  				ret = 0;
  			}
  		}
  	}
  	/*
  	 * If CPU is dropped to the lowest level, release the need
  	 * for a high bus frequency.
  	 */
  	if (old_freq > FREQ_396_MHZ && new_freq <= FREQ_396_MHZ)
  		release_bus_freq(BUS_FREQ_HIGH);
  
  	mutex_unlock(&set_cpufreq_lock);
  	return 0;
  }
  
  static int imx6q_cpufreq_init(struct cpufreq_policy *policy)
  {
  	int ret;
  
  	policy->clk = arm_clk;
  	policy->cur = clk_get_rate(arm_clk) / 1000;
  
  	ret = cpufreq_generic_init(policy, freq_table, transition_latency);
  	if (ret) {
  		dev_err(cpu_dev, "imx6 cpufreq init failed!
  ");
  		return ret;
  	}
  	if (policy->cur > FREQ_396_MHZ)
  		request_bus_freq(BUS_FREQ_HIGH);
  	return 0;
  }
  
  static struct cpufreq_driver imx6q_cpufreq_driver = {
  	.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
  	.verify = cpufreq_generic_frequency_table_verify,
  	.target_index = imx6q_set_target,
  	.get = cpufreq_generic_get,
  	.init = imx6q_cpufreq_init,
  	.exit = cpufreq_generic_exit,
  	.name = "imx6q-cpufreq",
  	.attr = cpufreq_generic_attr,
  };
  
  static int imx6_cpufreq_pm_notify(struct notifier_block *nb,
  	unsigned long event, void *dummy)
  {
  	struct cpufreq_policy *data = cpufreq_cpu_get(0);
  	static u32 cpufreq_policy_min_pre_suspend;
  
  	/*
  	 * During suspend/resume, When cpufreq driver try to increase
  	 * voltage/freq, it needs to control I2C/SPI to communicate
  	 * with external PMIC to adjust voltage, but these I2C/SPI
  	 * devices may be already suspended, to avoid such scenario,
  	 * we just increase cpufreq to highest setpoint before suspend.
  	 */
  	switch (event) {
  	case PM_SUSPEND_PREPARE:
  		cpufreq_policy_min_pre_suspend = data->user_policy.min;
  		data->user_policy.min = data->user_policy.max;
  		break;
  	case PM_POST_SUSPEND:
  		data->user_policy.min = cpufreq_policy_min_pre_suspend;
  		break;
  	default:
  		break;
  	}
  
  	cpufreq_update_policy(0);
  
  	return NOTIFY_OK;
  }
  
  static struct notifier_block imx6_cpufreq_pm_notifier = {
  	.notifier_call = imx6_cpufreq_pm_notify,
  };
  
  static int imx6q_cpufreq_probe(struct platform_device *pdev)
  {
  	struct device_node *np;
  	struct dev_pm_opp *opp;
  	unsigned long min_volt, max_volt;
  	int num, ret;
  	const struct property *prop;
  	const __be32 *val;
  	u32 nr, j, i = 0;
  
  	cpu_dev = get_cpu_device(0);
  	if (!cpu_dev) {
  		pr_err("failed to get cpu0 device
  ");
  		return -ENODEV;
  	}
  
  	np = of_node_get(cpu_dev->of_node);
  	if (!np) {
  		dev_err(cpu_dev, "failed to find cpu0 node
  ");
  		return -ENOENT;
  	}
  
  	arm_clk = devm_clk_get(cpu_dev, "arm");
  	pll1_sys_clk = devm_clk_get(cpu_dev, "pll1_sys");
  	pll1_sw_clk = devm_clk_get(cpu_dev, "pll1_sw");
  	step_clk = devm_clk_get(cpu_dev, "step");
  	pll2_pfd2_396m_clk = devm_clk_get(cpu_dev, "pll2_pfd2_396m");
  	pll1_bypass = devm_clk_get(cpu_dev, "pll1_bypass");
  	pll1 = devm_clk_get(cpu_dev, "pll1");
  	pll1_bypass_src = devm_clk_get(cpu_dev, "pll1_bypass_src");
  
  	if (IS_ERR(arm_clk) || IS_ERR(pll1_sys_clk) || IS_ERR(pll1_sw_clk) ||
  	    IS_ERR(step_clk) || IS_ERR(pll2_pfd2_396m_clk) ||
  	    IS_ERR(pll1_bypass) || IS_ERR(pll1) ||
  	    IS_ERR(pll1_bypass_src)) {
  		dev_err(cpu_dev, "failed to get clocks
  ");
  		ret = -ENOENT;
  		goto put_node;
  	}
  
  	arm_reg = devm_regulator_get_optional(cpu_dev, "arm");
  	pu_reg = devm_regulator_get_optional(cpu_dev, "pu");
  	soc_reg = devm_regulator_get_optional(cpu_dev, "soc");
  	if (IS_ERR(arm_reg) || IS_ERR(soc_reg)) {
  		dev_err(cpu_dev, "failed to get regulators
  ");
  		ret = -ENOENT;
  		goto put_node;
  	}
  
  	/*
  	 * soc_reg sync  with arm_reg if arm shares the same regulator
  	 * with soc. Otherwise, regulator common framework will refuse to update
  	 * this consumer's voltage right now while another consumer voltage
  	 * still keep in old one. For example, imx6sx-sdb with pfuze200 in
  	 * ldo-bypass mode.
  	 */
  	of_property_read_u32(np, "fsl,arm-soc-shared", &i);
  	if (i == 1)
  		soc_reg = arm_reg;
  	/*
  	 * 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 = of_init_opp_table(cpu_dev);
  		if (ret < 0) {
  			dev_err(cpu_dev, "failed to init OPP table: %d
  ", ret);
  			goto put_node;
  		}
  
  		num = dev_pm_opp_get_opp_count(cpu_dev);
  		if (num < 0) {
  			ret = num;
  			dev_err(cpu_dev, "no OPP table is found: %d
  ", ret);
  			goto put_node;
  		}
  	}
  
  	ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
  	if (ret) {
  		dev_err(cpu_dev, "failed to init cpufreq table: %d
  ", ret);
  		goto put_node;
  	}
  
  	/* Make imx6_soc_volt array's size same as arm opp number */
  	imx6_soc_volt = devm_kzalloc(cpu_dev, sizeof(*imx6_soc_volt) * num, GFP_KERNEL);
  	if (imx6_soc_volt == NULL) {
  		ret = -ENOMEM;
  		goto free_freq_table;
  	}
  
  	prop = of_find_property(np, "fsl,soc-operating-points", NULL);
  	if (!prop || !prop->value)
  		goto soc_opp_out;
  
  	/*
  	 * Each OPP is a set of tuples consisting of frequency and
  	 * voltage like <freq-kHz vol-uV>.
  	 */
  	nr = prop->length / sizeof(u32);
  	if (nr % 2 || (nr / 2) < num)
  		goto soc_opp_out;
  
  	for (j = 0; j < num; j++) {
  		val = prop->value;
  		for (i = 0; i < nr / 2; i++) {
  			unsigned long freq = be32_to_cpup(val++);
  			unsigned long volt = be32_to_cpup(val++);
  			if (freq_table[j].frequency == freq) {
  				imx6_soc_volt[soc_opp_count++] = volt;
  #ifdef CONFIG_MX6_VPU_352M
  				if (freq == 792000) {
  					pr_info("increase SOC/PU voltage for VPU352MHz
  ");
  					imx6_soc_volt[soc_opp_count - 1] = 1250000;
  				}
  #endif
  				break;
  			}
  		}
  	}
  
  soc_opp_out:
  	/* use fixed soc opp volt if no valid soc opp info found in dtb */
  	if (soc_opp_count != num) {
  		dev_warn(cpu_dev, "can NOT find valid fsl,soc-operating-points property in dtb, use default value!
  ");
  		for (j = 0; j < num; j++)
  			imx6_soc_volt[j] = PU_SOC_VOLTAGE_NORMAL;
  		if (freq_table[num - 1].frequency * 1000 == FREQ_1P2_GHZ)
  			imx6_soc_volt[num - 1] = PU_SOC_VOLTAGE_HIGH;
  	}
  
  	if (of_property_read_u32(np, "clock-latency", &transition_latency))
  		transition_latency = CPUFREQ_ETERNAL;
  
  	/*
  	 * Calculate the ramp time for max voltage change in the
  	 * VDDSOC and VDDPU regulators.
  	 */
  	ret = regulator_set_voltage_time(soc_reg, imx6_soc_volt[0], imx6_soc_volt[num - 1]);
  	if (ret > 0)
  		transition_latency += ret * 1000;
  	if (!IS_ERR(pu_reg)) {
  		ret = regulator_set_voltage_time(pu_reg, imx6_soc_volt[0],
  			imx6_soc_volt[num - 1]);
  		if (ret > 0)
  			transition_latency += ret * 1000;
  	}
  
  	/*
  	 * OPP is maintained in order of increasing frequency, and
  	 * freq_table initialised 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(&imx6q_cpufreq_driver);
  	if (ret) {
  		dev_err(cpu_dev, "failed register driver: %d
  ", ret);
  		goto free_freq_table;
  	}
  
  	mutex_init(&set_cpufreq_lock);
  	register_pm_notifier(&imx6_cpufreq_pm_notifier);
  
  	of_node_put(np);
  	return 0;
  
  free_freq_table:
  	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
  put_node:
  	of_node_put(np);
  	return ret;
  }
  
  static int imx6q_cpufreq_remove(struct platform_device *pdev)
  {
  	cpufreq_unregister_driver(&imx6q_cpufreq_driver);
  	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
  
  	return 0;
  }
  
  static struct platform_driver imx6q_cpufreq_platdrv = {
  	.driver = {
  		.name	= "imx6q-cpufreq",
  		.owner	= THIS_MODULE,
  	},
  	.probe		= imx6q_cpufreq_probe,
  	.remove		= imx6q_cpufreq_remove,
  };
  module_platform_driver(imx6q_cpufreq_platdrv);
  
  MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
  MODULE_DESCRIPTION("Freescale i.MX6Q cpufreq driver");
  MODULE_LICENSE("GPL");