2022-08-02 Analyze RK817 output 32k clock PMIC_32KOUT_WIFI to WiFi module clock register devm_clk_hw_register

一、RK817 输出32k clock PMIC_32KOUT_WIFI给WiFi模块,原理图如下

 

 二、查看datasheet,控制这个clk输出在0xf2寄存器.

 三、clk驱动在 kernel\drivers\clk\clk-rk808.c,其实就是通过i2c控制寄存器f2 enable 32k clk output.

/*
 * Clkout driver for Rockchip RK808
 *
 * Copyright (c) 2014, Fuzhou Rockchip Electronics Co., Ltd
 *
 * Author:Chris Zhong <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 */

#include <linux/clk-provider.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/mfd/rk808.h>
#include <linux/i2c.h>

struct rk808_clkout {
	struct rk808 *rk808;
	struct clk_hw		clkout1_hw;
	struct clk_hw		clkout2_hw;
};

static unsigned long rk808_clkout_recalc_rate(struct clk_hw *hw,
					      unsigned long parent_rate)
{
	return 32768;
}

static int rk808_clkout2_enable(struct clk_hw *hw, bool enable)
{
	struct rk808_clkout *rk808_clkout = container_of(hw,
							 struct rk808_clkout,
							 clkout2_hw);
	struct rk808 *rk808 = rk808_clkout->rk808;

	return regmap_update_bits(rk808->regmap, RK808_CLK32OUT_REG,
				  CLK32KOUT2_EN, enable ? CLK32KOUT2_EN : 0);
}

static int rk808_clkout2_prepare(struct clk_hw *hw)
{
	return rk808_clkout2_enable(hw, true);
}

static void rk808_clkout2_unprepare(struct clk_hw *hw)
{
	rk808_clkout2_enable(hw, false);
}

static int rk808_clkout2_is_prepared(struct clk_hw *hw)
{
	struct rk808_clkout *rk808_clkout = container_of(hw,
							 struct rk808_clkout,
							 clkout2_hw);
	struct rk808 *rk808 = rk808_clkout->rk808;
	uint32_t val;

	int ret = regmap_read(rk808->regmap, RK808_CLK32OUT_REG, &val);

	if (ret < 0)
		return ret;

	return (val & CLK32KOUT2_EN) ? 1 : 0;
}

static const struct clk_ops rk808_clkout1_ops = {
	.recalc_rate = rk808_clkout_recalc_rate,
};

static const struct clk_ops rk808_clkout2_ops = {
	.prepare = rk808_clkout2_prepare,
	.unprepare = rk808_clkout2_unprepare,
	.is_prepared = rk808_clkout2_is_prepared,
	.recalc_rate = rk808_clkout_recalc_rate,
};

static struct clk_hw *
of_clk_rk808_get(struct of_phandle_args *clkspec, void *data)
{
	struct rk808_clkout *rk808_clkout = data;
	unsigned int idx = clkspec->args[0];

	if (idx >= 2) {
		pr_err("%s: invalid index %u\n", __func__, idx);
		return ERR_PTR(-EINVAL);
	}

	return idx ? &rk808_clkout->clkout2_hw : &rk808_clkout->clkout1_hw;
}

static int rk817_clkout2_enable(struct clk_hw *hw, bool enable)
{
	struct rk808_clkout *rk808_clkout = container_of(hw,
							 struct rk808_clkout,
							 clkout2_hw);
	struct rk808 *rk808 = rk808_clkout->rk808;

	return regmap_update_bits(rk808->regmap, RK817_SYS_CFG(1),
				  RK817_CLK32KOUT2_EN,
				  enable ? RK817_CLK32KOUT2_EN : 0);
}

static int rk817_clkout2_prepare(struct clk_hw *hw)
{
	return rk817_clkout2_enable(hw, true);
}

static void rk817_clkout2_unprepare(struct clk_hw *hw)
{
	rk817_clkout2_enable(hw, false);
}

static int rk817_clkout2_is_prepared(struct clk_hw *hw)
{
	struct rk808_clkout *rk808_clkout = container_of(hw,
							 struct rk808_clkout,
							 clkout2_hw);
	struct rk808 *rk808 = rk808_clkout->rk808;
	unsigned int val;

	int ret = regmap_read(rk808->regmap, RK817_SYS_CFG(1), &val);

	if (ret < 0)
		return 0;

	return (val & RK817_CLK32KOUT2_EN) ? 1 : 0;
}

static const struct clk_ops rk817_clkout2_ops = {
	.prepare = rk817_clkout2_prepare,
	.unprepare = rk817_clkout2_unprepare,
	.is_prepared = rk817_clkout2_is_prepared,
	.recalc_rate = rk808_clkout_recalc_rate,
};

static const struct clk_ops *rkpmic_get_ops(long variant)
{
	switch (variant) {
	case RK809_ID:
	case RK817_ID:
		return &rk817_clkout2_ops;
	/*
	 * For the default case, it match the following PMIC type.
	 * RK805_ID
	 * RK808_ID
	 * RK818_ID
	 */
	default:
		return &rk808_clkout2_ops;
	}
}

static int rk808_clkout_probe(struct platform_device *pdev)
{
	struct rk808 *rk808 = dev_get_drvdata(pdev->dev.parent);
	struct i2c_client *client = rk808->i2c;
	struct device_node *node = client->dev.of_node;
	struct clk_init_data init = {};
	struct rk808_clkout *rk808_clkout;
	int ret;

	rk808_clkout = devm_kzalloc(&client->dev,
				    sizeof(*rk808_clkout), GFP_KERNEL);
	if (!rk808_clkout)
		return -ENOMEM;

	rk808_clkout->rk808 = rk808;

	init.parent_names = NULL;
	init.num_parents = 0;
	init.name = "rk808-clkout1";
	init.ops = &rk808_clkout1_ops;
	rk808_clkout->clkout1_hw.init = &init;

	/* optional override of the clockname */
	of_property_read_string_index(node, "clock-output-names",
				      0, &init.name);

	ret = devm_clk_hw_register(&client->dev, &rk808_clkout->clkout1_hw);
	if (ret)
		return ret;

	init.name = "rk808-clkout2";
	init.ops = rkpmic_get_ops(rk808->variant);
	rk808_clkout->clkout2_hw.init = &init;

	/* optional override of the clockname */
	of_property_read_string_index(node, "clock-output-names",
				      1, &init.name);

	ret = devm_clk_hw_register(&client->dev, &rk808_clkout->clkout2_hw);
	if (ret)
		return ret;

	return of_clk_add_hw_provider(node, of_clk_rk808_get, rk808_clkout);
}

static int rk808_clkout_remove(struct platform_device *pdev)
{
	struct rk808 *rk808 = dev_get_drvdata(pdev->dev.parent);
	struct i2c_client *client = rk808->i2c;
	struct device_node *node = client->dev.of_node;

	of_clk_del_provider(node);

	return 0;
}

static struct platform_driver rk808_clkout_driver = {
	.probe = rk808_clkout_probe,
	.remove = rk808_clkout_remove,
	.driver		= {
		.name	= "rk808-clkout",
	},
};

module_platform_driver(rk808_clkout_driver);

MODULE_DESCRIPTION("Clkout driver for the rk808 series PMICs");
MODULE_AUTHOR("Chris Zhong <[email protected]>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:rk808-clkout");

四、用cat d/clk/clk_summary 命令查看是否注册成功

 五、rk817中clock相关的dts配置

 六、需要用到clk的WIFI驱动的dts的配置

 七、获取clock并使能

 

八、使能该clk后,0xf2寄存器CLK32KOUT_EN会变1.

九、有价值的参考文章

RK808 32KCan't get the hour hand_AndroidDiff的博客-CSDN博客