Date:   Wed, 6 Sep 2017 17:30:25 +0530
From:   Tirupathi Reddy T <tirupath@...eaurora.org>
To:     Stephen Boyd <sboyd@...eaurora.org>
Cc:     mturquette@...libre.com, robh+dt@...nel.org, mark.rutland@....com,
        andy.gross@...aro.org, david.brown@...aro.org,
        linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-soc@...r.kernel.org
Subject: Re: [PATCH V2] clk: qcom: Add spmi_pmic clock divider support



On 9/2/2017 1:56 AM, Stephen Boyd wrote:
> On 08/31, Tirupathi Reddy wrote:
>> diff --git a/Documentation/devicetree/bindings/clock/clk-spmi-pmic-div.txt b/Documentation/devicetree/bindings/clock/clk-spmi-pmic-div.txt
>> new file mode 100644
>> index 0000000..48cb2f7
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/clock/clk-spmi-pmic-div.txt
>> @@ -0,0 +1,49 @@
>> +Qualcomm Technologies, Inc. SPMI PMIC clock divider (clkdiv)
>> +
>> +clkdiv configures the clock frequency of a set of outputs on the PMIC.
>> +These clocks are typically wired through alternate functions on
>> +gpio pins.
>> +
>> +=======================
>> +Supported Properties
> Just "Properties".
address in next patch set.
>
>> +=======================
>> +
>> +- compatible
>> +	Usage:      required
>> +	Value type: <string>
>> +	Definition: should be "qcom,spmi-pmic-clkdiv".
>> +
>> +- reg
>> +	Usage:      required
>> +	Value type: <prop-encoded-array>
>> +	Definition: Addresses and sizes for the memory of this CLKDIV
>> +		    peripheral.
>> +
>> +- clocks:
>> +	Usage: required
>> +	Value type: <prop-encoded-array>
>> +	Definition: reference to the xo clock.
>> +
>> +- clock-names:
>> +	Usage: required
>> +	Value type: <stringlist>
>> +	Definition: must be "xo".
>> +
>> +=======
>> +Example
>> +=======
>> +
>> +pm8998_clk_divs: qcom,clkdiv@0 {
> @5b00
address in next patch set.
>
>> +	compatible = "qcom,spmi-pmic-clkdiv";
>> +	reg = <0x5b00 0x300>;
> Drop the size
address in next patch set.
>
>> +	#clock-cells = <1>;
>> +	clocks = <&xo_board>;
>> +	clock-names = "xo";
>> +
>> +	assigned-clocks = <&pm8998_clk_divs CLKDIV1>,
>> +			  <&pm8998_clk_divs CLKDIV2>,
>> +			  <&pm8998_clk_divs CLKDIV3>;
>> +	assigned-clock-rates = <9600000>,
>> +			       <9600000>,
>> +			       <9600000>;
> Not sure we need this part in the example, but OK.
>
>> +};
>> diff --git a/drivers/clk/qcom/Kconfig b/drivers/clk/qcom/Kconfig
>> index 9f6c278..af5e489 100644
>> --- a/drivers/clk/qcom/Kconfig
>> +++ b/drivers/clk/qcom/Kconfig
>> @@ -196,3 +196,12 @@ config MSM_MMCC_8996
>>   	  Support for the multimedia clock controller on msm8996 devices.
>>   	  Say Y if you want to support multimedia devices such as display,
>>   	  graphics, video encode/decode, camera, etc.
>> +
>> +config CLOCK_SPMI_PMIC_DIV
> config SPMI_PMIC_CLKDIV?
address in next patch set.
>
>> +	tristate "spmi pmic clkdiv driver"
>> +	depends on (COMMON_CLK_QCOM && SPMI) || COMPILE_TEST
>> +	help
>> +	  This driver supports the clkdiv functionality on the Qualcomm
>> +	  Technologies, Inc. SPMI PMIC. It configures the frequency of
>> +	  clkdiv outputs on the PMIC. These clocks are typically wired
>> +	  through alternate functions on gpio pins.
>> diff --git a/drivers/clk/qcom/Makefile b/drivers/clk/qcom/Makefile
>> index 3f3aff2..ee8c91c 100644
>> --- a/drivers/clk/qcom/Makefile
>> +++ b/drivers/clk/qcom/Makefile
>> @@ -15,6 +15,7 @@ clk-qcom-$(CONFIG_QCOM_GDSC) += gdsc.o
>>   # Keep alphabetically sorted by config
>>   obj-$(CONFIG_APQ_GCC_8084) += gcc-apq8084.o
>>   obj-$(CONFIG_APQ_MMCC_8084) += mmcc-apq8084.o
>> +obj-$(CONFIG_CLOCK_SPMI_PMIC_DIV) += clk-spmi-pmic-div.o
>>   obj-$(CONFIG_IPQ_GCC_4019) += gcc-ipq4019.o
>>   obj-$(CONFIG_IPQ_GCC_806X) += gcc-ipq806x.o
>>   obj-$(CONFIG_IPQ_GCC_8074) += gcc-ipq8074.o
>> diff --git a/drivers/clk/qcom/clk-spmi-pmic-div.c b/drivers/clk/qcom/clk-spmi-pmic-div.c
>> new file mode 100644
>> index 0000000..24461fb
>> --- /dev/null
>> +++ b/drivers/clk/qcom/clk-spmi-pmic-div.c
>> @@ -0,0 +1,327 @@
>> +/* Copyright (c) 2017, The Linux Foundation. All rights reserved.
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 and
>> + * only version 2 as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that 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/bitops.h>
>> +#include <linux/clk.h>
>> +#include <linux/clk-provider.h>
>> +#include <linux/delay.h>
>> +#include <linux/err.h>
>> +#include <linux/log2.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
> Needed?
remove it in next patch set.
>
>> +#include <linux/platform_device.h>
>> +#include <linux/regmap.h>
>> +#include <linux/slab.h>
>> +#include <linux/types.h>
>> +
>> +#include <dt-bindings/clock/spmi_pmic_clk_div.h>
>> +
>> +#define REG_DIV_CTL1			0x43
>> +#define DIV_CTL1_DIV_FACTOR_MASK	GENMASK(2, 0)
>> +
>> +#define REG_EN_CTL			0x46
>> +#define REG_EN_MASK			BIT(7)
>> +#define REG_EN_SET			BIT(7)
> Why do we need this define? Just test if the mask comes out to be
> non-zero instead.
okay. address in next patch set.
>
>> +
>> +#define ENABLE_DELAY_NS(cxo_ns, div)	((2 + 3 * div) * cxo_ns)
>> +#define DISABLE_DELAY_NS(cxo_ns, div)	((3 * div) * cxo_ns)
>> +
>> +#define CLK_SPMI_PMIC_DIV_OFFSET	1
>> +
>> +#define CLKDIV_XO_DIV_1_0		0
>> +#define CLKDIV_XO_DIV_1			1
>> +#define CLKDIV_XO_DIV_2			2
>> +#define CLKDIV_XO_DIV_4			3
>> +#define CLKDIV_XO_DIV_8			4
>> +#define CLKDIV_XO_DIV_16		5
>> +#define CLKDIV_XO_DIV_32		6
>> +#define CLKDIV_XO_DIV_64		7
>> +#define CLKDIV_MAX_ALLOWED		8
>> +
>> +struct clkdiv {
>> +	struct regmap		*regmap;
>> +	u16			base;
>> +
>> +	/* clock properties */
>> +	struct clk_hw		hw;
>> +	unsigned int		div_factor;
>> +	unsigned int		cxo_period_ns;
>> +};
>> +
>> +struct spmi_pmic_div_clk_cc {
>> +	struct clk_hw	**div_clks;
> I don't understand this design. Shouldn't we just allocate an
> array of clkdiv structure?
This design is for addressing the invalid value passed in 
spmi_pmic_div_clk_hw_get().
>
>> +	int		nclks;
>> +};
>> +
>> +static inline struct clkdiv *to_clkdiv(struct clk_hw *hw)
>> +{
>> +	return container_of(hw, struct clkdiv, hw);
>> +}
>> +
>> +static inline unsigned int div_factor_to_div(unsigned int div_factor)
>> +{
>> +	if (div_factor == CLKDIV_XO_DIV_1_0)
>> +		return 1;
>> +
>> +	return 1 << (div_factor - CLK_SPMI_PMIC_DIV_OFFSET);
>> +}
>> +
>> +static inline unsigned int div_to_div_factor(unsigned int div)
>> +{
>> +	return ilog2(div) + CLK_SPMI_PMIC_DIV_OFFSET;
> Maybe we should do the clamp here?
okay. address in next patch set.
>
>> +}
>> +
>> +static bool is_spmi_pmic_clkdiv_enabled(struct clkdiv *clkdiv)
>> +{
>> +	unsigned int val = 0;
>> +
>> +	regmap_read(clkdiv->regmap, clkdiv->base + REG_EN_CTL,
>> +			 &val);
>> +	return ((val & REG_EN_MASK) == REG_EN_SET) ? true : false;
>> +}
>> +
>> +static int spmi_pmic_clkdiv_set_enable_state(struct clkdiv *clkdiv,
>> +			bool enable_state)
>> +{
>> +	int rc;
>> +
>> +	rc = regmap_update_bits(clkdiv->regmap, clkdiv->base + REG_EN_CTL,
>> +				REG_EN_MASK,
>> +				(enable_state == true) ? REG_EN_SET : 0);
>> +	if (rc)
>> +		return rc;
>> +
>> +	if (enable_state == true)
>> +		ndelay(ENABLE_DELAY_NS(clkdiv->cxo_period_ns,
>> +				div_factor_to_div(clkdiv->div_factor)));
>> +	else
>> +		ndelay(DISABLE_DELAY_NS(clkdiv->cxo_period_ns,
>> +				div_factor_to_div(clkdiv->div_factor)));
>> +
>> +	return rc;
>> +}
>> +
>> +static int spmi_pmic_clkdiv_config_freq_div(struct clkdiv *clkdiv,
>> +			unsigned int div)
>> +{
>> +	unsigned int div_factor;
>> +	bool enabled;
>> +	int rc;
>> +
>> +	div_factor = div_to_div_factor(div);
>> +	if (div_factor <= 0 || div_factor >= CLKDIV_MAX_ALLOWED)
> div_factor is unsigned. It can't be less than 0.
okay. address in next patch set.
>
>> +		return -EINVAL;
>> +
>> +	enabled = is_spmi_pmic_clkdiv_enabled(clkdiv);
>> +	if (enabled) {
>> +		rc = spmi_pmic_clkdiv_set_enable_state(clkdiv, false);
>> +		if (rc)
>> +			return rc;
> This races with clk_enable() on the same clk. You'll need some
> sort of local lock to make sure set_rate() and enable don't race
> with each other.
okay. address in next patch set.
>> +	}
>> +
>> +	rc = regmap_update_bits(clkdiv->regmap,
>> +				clkdiv->base + REG_DIV_CTL1,
>> +				DIV_CTL1_DIV_FACTOR_MASK, div_factor);
>> +	if (rc)
>> +		return rc;
>> +
>> +	clkdiv->div_factor = div_factor;
>> +
>> +	if (enabled)
>> +		rc = spmi_pmic_clkdiv_set_enable_state(clkdiv, true);
>> +
>> +	return rc;
>> +}
>> +
>> +static int clk_spmi_pmic_div_enable(struct clk_hw *hw)
>> +{
>> +	struct clkdiv *clkdiv = to_clkdiv(hw);
>> +
>> +	return spmi_pmic_clkdiv_set_enable_state(clkdiv, true);
>> +}
>> +
>> +static void clk_spmi_pmic_div_disable(struct clk_hw *hw)
>> +{
>> +	struct clkdiv *clkdiv = to_clkdiv(hw);
>> +
>> +	spmi_pmic_clkdiv_set_enable_state(clkdiv, false);
>> +}
>> +
>> +static long clk_spmi_pmic_div_round_rate(struct clk_hw *hw, unsigned long rate,
>> +			unsigned long *parent_rate)
>> +{
>> +	unsigned long new_rate;
>> +	unsigned int div, div_factor;
>> +
>> +	div = DIV_ROUND_UP(*parent_rate, rate);
>> +	div_factor = div_to_div_factor(div);
>> +	if (div_factor >= CLKDIV_MAX_ALLOWED)
>> +		div_factor = CLKDIV_MAX_ALLOWED - 1;
> min()?
okay. address in next patch set.
>
>> +	new_rate = *parent_rate / div_factor_to_div(div_factor);
>> +
>> +	return new_rate;
>> +}
>> +
>> +static unsigned long clk_spmi_pmic_div_recalc_rate(struct clk_hw *hw,
>> +			unsigned long parent_rate)
>> +{
>> +	struct clkdiv *clkdiv = to_clkdiv(hw);
>> +	unsigned long rate;
>> +
>> +	rate = parent_rate / div_factor_to_div(clkdiv->div_factor);
>> +
>> +	return rate;
>> +}
>> +
>> +static int clk_spmi_pmic_div_set_rate(struct clk_hw *hw, unsigned long rate,
>> +			unsigned long parent_rate)
>> +{
>> +	struct clkdiv *clkdiv = to_clkdiv(hw);
>> +	int rc = 0;
> Please don't assign variables that are then reassigned right
> after.
okay. address in next patch set.
>
>> +
>> +	rc = spmi_pmic_clkdiv_config_freq_div(clkdiv, parent_rate / rate);
>> +
> And also just return things when you can instead of assigning
> them to local variables to return after.
okay. address in next patch set.
>
>> +	return rc;
>> +}
>> +
>> +static const struct clk_ops clk_spmi_pmic_div_ops = {
>> +	.enable = clk_spmi_pmic_div_enable,
>> +	.disable = clk_spmi_pmic_div_disable,
>> +	.set_rate = clk_spmi_pmic_div_set_rate,
>> +	.recalc_rate = clk_spmi_pmic_div_recalc_rate,
>> +	.round_rate = clk_spmi_pmic_div_round_rate,
>> +};
>> +
>> +static struct clk_hw *spmi_pmic_div_clk_hw_get(struct of_phandle_args *clkspec,
>> +				      void *data)
>> +{
>> +	struct spmi_pmic_div_clk_cc *clk_cc = data;
>> +	unsigned int idx = clkspec->args[0];
>> +
>> +	if (idx >= clk_cc->nclks) {
>> +		pr_err("%s: invalid index %u\n", __func__, idx);
>> +		return ERR_PTR(-EINVAL);
>> +	}
>> +
>> +	return clk_cc->div_clks[idx];
>> +}
>> +
>> +#define SPMI_PMIC_DIV_CLK_ADDRESS_RANGE	0x100
> SPMI_PMIC_DIV_CLK_SIZE?
okay. address in next patch set.
>
>> +#define SPMI_PMIC_DIV_CLK_ID_OFFSET	1
>> +
>> +static int spmi_pmic_clkdiv_probe(struct platform_device *pdev)
>> +{
>> +	struct spmi_pmic_div_clk_cc *clk_cc;
>> +	struct clk_init_data init = {0};
> Drop the 0 part.
okay. address in next patch set.
>
>> +	struct clkdiv *clkdiv;
>> +	struct clk *cxo;
>> +	struct regmap *regmap;
>> +	struct device *dev = &pdev->dev;
>> +	const char *parent_name;
>> +	int nclks, i, rc, cxo_hz;
>> +	u32 reg[2], start, size;
>> +
>> +	rc = of_property_read_u32_array(dev->of_node, "reg", reg, 2);
> Oh hm... I think I suggested we count the size, but that may not
> work. The SPMI node has #address-cells = 1 and #size-cells = 0.
> So the reg property will only have one cell and it will be the
> offset. We could count the interrupts. Or we could count
> clock-output-names. Or we can match a certain PMIC compatible
> string and then know the size from some hardcoded number in this
> driver.
okay. address in next patch set.
>
>> +	if (rc < 0) {
>> +		dev_err(dev, "reg property reading failed\n");
>> +		return rc;
>> +	}
>> +	start = reg[0];
>> +	size = reg[1];
>> +
>> +	nclks = size / SPMI_PMIC_DIV_CLK_ADDRESS_RANGE;
>> +	if (nclks == 0) {
>> +		dev_err(dev, "no div clocks assigned\n");
> This should never happen?
okay. remove it in next patch set.
>
>> +		return -ENODEV;
>> +	}
>> +
>> +	regmap = dev_get_regmap(dev->parent, NULL);
>> +	if (!regmap) {
>> +		dev_err(dev, "Couldn't get parent's regmap\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	clkdiv = devm_kcalloc(dev, nclks, sizeof(*clkdiv), GFP_KERNEL);
>> +	if (!clkdiv)
>> +		return -ENOMEM;
>> +
>> +	clk_cc = devm_kzalloc(&pdev->dev, sizeof(*clk_cc), GFP_KERNEL);
>> +	if (!clk_cc)
>> +		return -ENOMEM;
>> +
>> +	clk_cc->div_clks = devm_kcalloc(&pdev->dev, nclks,
>> +					sizeof(*clk_cc->div_clks), GFP_KERNEL);
>> +	if (!clk_cc->div_clks)
>> +		return -ENOMEM;
>> +
>> +	/* Read parent clock rate */
> That's obvious.
okay. remove it in next patch set.
>
>> +	cxo = of_clk_get(dev->of_node, 0);
> Just use clk_get() instead? This is a platform driver after all.
okay. address in next patch set.
>
>> +	if (IS_ERR(cxo)) {
>> +		rc = PTR_ERR(cxo);
>> +		if (rc != -EPROBE_DEFER)
>> +			dev_err(dev, "failed to get xo clock");
>> +		return rc;
>> +	}
>> +	cxo_hz = clk_get_rate(cxo);
>> +	clk_put(cxo);
>> +
>> +	parent_name = of_clk_get_parent_name(dev->of_node, 0);
>> +	if (!parent_name) {
>> +		dev_err(dev, "missing parent clock\n");
>> +		return -ENODEV;
>> +	}
>> +	dev_dbg(dev, "parent is: %s\n", parent_name);
> Remove?
okay. address in next patch set.
>
>> +
>> +	init.parent_names = &parent_name;
>> +	init.num_parents = parent_name ? 1 : 0;
>> +	init.ops = &clk_spmi_pmic_div_ops;
>> +	init.flags = 0;
>> +
>> +	for (i = 0; i < nclks; i++) {
>> +		clkdiv[i].base = start + i * SPMI_PMIC_DIV_CLK_ADDRESS_RANGE;
>> +		clkdiv[i].regmap = regmap;
>> +		clkdiv[i].cxo_period_ns = NSEC_PER_SEC / cxo_hz;
>> +		init.name = kasprintf(GFP_KERNEL, "div_clk%d",
>> +				     i + SPMI_PMIC_DIV_CLK_ID_OFFSET);
> We don't need a define for 1.
>
>> +		clkdiv[i].hw.init = &init;
>> +		rc = devm_clk_hw_register(dev, &clkdiv[i].hw);
>> +		if (rc)
> We leak init.name here.
>
>> +			return rc;
>> +
>> +		clk_cc->div_clks[i] = &clkdiv[i].hw;
>> +		kfree(init.name); /* clock framework made a copy of the name */
>> +	}
>> +
>> +	clk_cc->nclks = nclks;
>> +	rc = of_clk_add_hw_provider(pdev->dev.of_node, spmi_pmic_div_clk_hw_get,
>> +				    clk_cc);
> Urgh, we really need this devmified. Patch coming tomorrow. For
> now, you need a remove function for driver unbinding to
> unregister the provider.
okay. address in next patch set.
>> +	return rc;
>> +}
>> +
>> +static const struct of_device_id spmi_pmic_clkdiv_match_table[] = {
>> +	{ .compatible = "qcom,spmi-pmic-clkdiv" },
> I'm not sure we call it this in other places. How about
> qcom,spmi-clkdiv and then have specific one for the pmic as well
> in case we ever care in the future like qcom,pm8916-clkdiv, etc.
okay. address in next patch set.
>
>> +	{}
>> +};
>> +MODULE_DEVICE_TABLE(of, spmi_pmic_clkdiv_match_table);
>> +
>> +static struct platform_driver spmi_pmic_clkdiv_driver = {
>> +	.driver		= {
>> +		.name	= "qcom,spmi-pmic-clkdiv",
>> +		.of_match_table = spmi_pmic_clkdiv_match_table,
>> +	},
>> +	.probe		= spmi_pmic_clkdiv_probe,
>> +};
>> +module_platform_driver(spmi_pmic_clkdiv_driver);
>> +
>> +MODULE_DESCRIPTION("spmi pmic clkdiv driver");
> QCOM SPMI PMIC clkdiv driver?
okay. address in next patch set.
>
>> +MODULE_LICENSE("GPL v2");
>> diff --git a/include/dt-bindings/clock/spmi_pmic_clk_div.h b/include/dt-bindings/clock/spmi_pmic_clk_div.h
>> new file mode 100644
>> index 0000000..25d035d
>> --- /dev/null
>> +++ b/include/dt-bindings/clock/spmi_pmic_clk_div.h
>> @@ -0,0 +1,21 @@
>> +/*
>> + * Copyright (c) 2017, The Linux Foundation. All rights reserved.
>> + *
>> + * This software is licensed under the terms of the GNU General Public
>> + * License version 2, as published by the Free Software Foundation, and
>> + * may be copied, distributed, and modified under those terms.
>> + *
>> + * This program is distributed in the hope that 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.
>> + */
>> +
>> +#ifndef _DT_BINDINGS_SPMI_PMIC_CLK_DIV_H
>> +#define _DT_BINDINGS_SPMI_PMIC_CLK_DIV_H
>> +
>> +#define CLKDIV1		0
> 1 is 0...
>
>> +#define CLKDIV2		1
> 2 is 1...
>
>> +#define CLKDIV3		2
> How about we offset the index once and then drop the header file?
okay. address in next patch set.
>

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