Date:   Sun, 28 Nov 2021 01:38:34 +0200
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Hans de Goede <hdegoede@redhat.com>
Cc:     "Rafael J . Wysocki" <rjw@rjwysocki.net>,
        Mark Gross <markgross@kernel.org>,
        Andy Shevchenko <andy@infradead.org>,
        Wolfram Sang <wsa@the-dreams.de>,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        Daniel Scally <djrscally@gmail.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Mark Brown <broonie@kernel.org>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>, Len Brown <lenb@kernel.org>,
        linux-acpi@vger.kernel.org, platform-driver-x86@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        Kate Hsuan <hpa@redhat.com>, linux-media@vger.kernel.org,
        linux-clk@vger.kernel.org,
        Andy Shevchenko <andy.shevchenko@gmail.com>
Subject: Re: [PATCH v6 05/15] regulator: Introduce tps68470-regulator driver
Message-ID: <YaLBeq0+0A6R2FZG@pendragon.ideasonboard.com>
References: <20211125165412.535063-1-hdegoede@redhat.com>
 <20211125165412.535063-6-hdegoede@redhat.com>
 <YaAdIG+2MZPsdI+F@pendragon.ideasonboard.com>
 <19aeff06-d397-5f88-6d07-f76a2073b682@redhat.com>
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In-Reply-To: <19aeff06-d397-5f88-6d07-f76a2073b682@redhat.com>
Precedence: bulk

Hi Hans,

On Fri, Nov 26, 2021 at 12:22:35PM +0100, Hans de Goede wrote:
> On 11/26/21 00:32, Laurent Pinchart wrote:
> > On Thu, Nov 25, 2021 at 05:54:02PM +0100, Hans de Goede wrote:
> >> The TPS68470 PMIC provides Clocks, GPIOs and Regulators. At present in
> >> the kernel the Regulators and Clocks are controlled by an OpRegion
> >> driver designed to work with power control methods defined in ACPI, but
> >> some platforms lack those methods, meaning drivers need to be able to
> >> consume the resources of these chips through the usual frameworks.
> >>
> >> This commit adds a driver for the regulators provided by the tps68470,
> >> and is designed to bind to the platform_device registered by the
> >> intel_skl_int3472 module.
> >>
> >> This is based on this out of tree driver written by Intel:
> >> https://github.com/intel/linux-intel-lts/blob/4.14/base/drivers/regulator/tps68470-regulator.c
> >> with various cleanups added.
> >>
> >> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> >> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> >> ---
> >> Changes in v6:
> >> - Drop the unused volt_table argument from the TPS68470_REGULATOR() macro
> >> - While working on VCM (voice coil motor) support for the camera-module behind
> >>   this PMIC I learned that the VIO voltage is always on. Instead of pointing its
> >>   enable_reg and enable_mask at the same register-bits as the VSIO regulator
> >>   (which is wrong), add a new tps68470_always_on_reg_ops struct without
> >>   is_enabled, enable and disable ops and use that for the VIO regulator.
> >>
> >> Changes in v5:
> >> - Small comment / code cleanups based on review from Andy
> >>
> >> Changes in v4:
> >> - Make the top comment block use c++ style comments
> >> - Drop the bogus builtin regulator_init_data
> >> - Add || COMPILE_TEST to Kconfig snippet
> >> - Make the driver enable the PMIC clk when enabling the Core buck
> >>   regulator, this switching regulator needs the PLL to be on
> >>
> >> Changes in v2:
> >> - Update the comment on why a subsys_initcall is used to register the drv
> >> - Make struct regulator_ops const
> >> ---
> >>  drivers/regulator/Kconfig              |   9 ++
> >>  drivers/regulator/Makefile             |   1 +
> >>  drivers/regulator/tps68470-regulator.c | 201 +++++++++++++++++++++++++
> >>  3 files changed, 211 insertions(+)
> >>  create mode 100644 drivers/regulator/tps68470-regulator.c
> >>
> >> diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
> >> index 6be9b1c8a615..ebe46e09510e 100644
> >> --- a/drivers/regulator/Kconfig
> >> +++ b/drivers/regulator/Kconfig
> >> @@ -1339,6 +1339,15 @@ config REGULATOR_TPS65912
> >>  	help
> >>  	    This driver supports TPS65912 voltage regulator chip.
> >>  
> >> +config REGULATOR_TPS68470
> >> +	tristate "TI TPS68470 PMIC Regulators Driver"
> >> +	depends on INTEL_SKL_INT3472 || COMPILE_TEST
> >> +	help
> >> +	  This driver adds support for the TPS68470 PMIC to register
> >> +	  regulators against the usual framework.
> >> +
> >> +	  The module will be called "tps68470-regulator".
> >> +
> >>  config REGULATOR_TWL4030
> >>  	tristate "TI TWL4030/TWL5030/TWL6030/TPS659x0 PMIC"
> >>  	depends on TWL4030_CORE
> >> diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
> >> index b07d2a22df0b..257331d2caed 100644
> >> --- a/drivers/regulator/Makefile
> >> +++ b/drivers/regulator/Makefile
> >> @@ -159,6 +159,7 @@ obj-$(CONFIG_REGULATOR_TPS6586X) += tps6586x-regulator.o
> >>  obj-$(CONFIG_REGULATOR_TPS65910) += tps65910-regulator.o
> >>  obj-$(CONFIG_REGULATOR_TPS65912) += tps65912-regulator.o
> >>  obj-$(CONFIG_REGULATOR_TPS65132) += tps65132-regulator.o
> >> +obj-$(CONFIG_REGULATOR_TPS68470) += tps68470-regulator.o
> >>  obj-$(CONFIG_REGULATOR_TWL4030) += twl-regulator.o twl6030-regulator.o
> >>  obj-$(CONFIG_REGULATOR_UNIPHIER) += uniphier-regulator.o
> >>  obj-$(CONFIG_REGULATOR_VCTRL) += vctrl-regulator.o
> >> diff --git a/drivers/regulator/tps68470-regulator.c b/drivers/regulator/tps68470-regulator.c
> >> new file mode 100644
> >> index 000000000000..9ad2d1eae8fe
> >> --- /dev/null
> >> +++ b/drivers/regulator/tps68470-regulator.c
> >> @@ -0,0 +1,201 @@
> >> +// SPDX-License-Identifier: GPL-2.0
> >> +//
> >> +// Regulator driver for TPS68470 PMIC
> >> +//
> >> +// Copyright (c) 2021 Red Hat Inc.
> >> +// Copyright (C) 2018 Intel Corporation
> >> +//
> >> +// Authors:
> >> +//	Hans de Goede <hdegoede@redhat.com>
> >> +//	Zaikuo Wang <zaikuo.wang@intel.com>
> >> +//	Tianshu Qiu <tian.shu.qiu@intel.com>
> >> +//	Jian Xu Zheng <jian.xu.zheng@intel.com>
> >> +//	Yuning Pu <yuning.pu@intel.com>
> >> +//	Rajmohan Mani <rajmohan.mani@intel.com>
> >> +
> >> +#include <linux/clk.h>
> >> +#include <linux/device.h>
> >> +#include <linux/err.h>
> >> +#include <linux/init.h>
> >> +#include <linux/kernel.h>
> >> +#include <linux/mfd/tps68470.h>
> >> +#include <linux/module.h>
> >> +#include <linux/platform_data/tps68470.h>
> >> +#include <linux/platform_device.h>
> >> +#include <linux/regulator/driver.h>
> >> +#include <linux/regulator/machine.h>
> >> +
> >> +struct tps68470_regulator_data {
> >> +	struct clk *clk;
> >> +};
> >> +
> >> +#define TPS68470_REGULATOR(_name, _id, _ops, _n,			\
> >> +			   _vr, _vm, _er, _em, _lr, _nlr)		\
> >> +	[TPS68470_ ## _name] = {					\
> >> +		.name			= # _name,			\
> >> +		.id			= _id,				\
> >> +		.ops			= &_ops,			\
> >> +		.n_voltages		= _n,				\
> >> +		.type			= REGULATOR_VOLTAGE,		\
> >> +		.owner			= THIS_MODULE,			\
> >> +		.vsel_reg		= _vr,				\
> >> +		.vsel_mask		= _vm,				\
> >> +		.enable_reg		= _er,				\
> >> +		.enable_mask		= _em,				\
> >> +		.linear_ranges		= _lr,				\
> >> +		.n_linear_ranges	= _nlr,				\
> >> +	}
> >> +
> >> +static const struct linear_range tps68470_ldo_ranges[] = {
> >> +	REGULATOR_LINEAR_RANGE(875000, 0, 125, 17800),
> >> +};
> >> +
> >> +static const struct linear_range tps68470_core_ranges[] = {
> >> +	REGULATOR_LINEAR_RANGE(900000, 0, 42, 25000),
> >> +};
> >> +
> >> +static int tps68470_regulator_enable(struct regulator_dev *rdev)
> >> +{
> >> +	struct tps68470_regulator_data *data = rdev->reg_data;
> >> +	int ret;
> >> +
> >> +	/* The Core buck regulator needs the PMIC's PLL to be enabled */
> >> +	if (rdev->desc->id == TPS68470_CORE) {
> >> +		ret = clk_prepare_enable(data->clk);
> >> +		if (ret) {
> >> +			dev_err(&rdev->dev, "Error enabling TPS68470 clock\n");
> >> +			return ret;
> >> +		}
> >> +	}
> >> +
> >> +	return regulator_enable_regmap(rdev);
> >> +}
> >> +
> >> +static int tps68470_regulator_disable(struct regulator_dev *rdev)
> >> +{
> >> +	struct tps68470_regulator_data *data = rdev->reg_data;
> >> +
> >> +	if (rdev->desc->id == TPS68470_CORE)
> >> +		clk_disable_unprepare(data->clk);
> >> +
> >> +	return regulator_disable_regmap(rdev);
> >> +}
> >> +
> >> +/* Operations permitted on DCDCx, LDO2, LDO3 and LDO4 */
> >> +static const struct regulator_ops tps68470_regulator_ops = {
> >> +	.is_enabled		= regulator_is_enabled_regmap,
> >> +	.enable			= tps68470_regulator_enable,
> >> +	.disable		= tps68470_regulator_disable,
> >> +	.get_voltage_sel	= regulator_get_voltage_sel_regmap,
> >> +	.set_voltage_sel	= regulator_set_voltage_sel_regmap,
> >> +	.list_voltage		= regulator_list_voltage_linear_range,
> >> +	.map_voltage		= regulator_map_voltage_linear_range,
> >> +};
> >> +
> >> +static const struct regulator_ops tps68470_always_on_reg_ops = {
> >> +	.get_voltage_sel	= regulator_get_voltage_sel_regmap,
> >> +	.set_voltage_sel	= regulator_set_voltage_sel_regmap,
> >> +	.list_voltage		= regulator_list_voltage_linear_range,
> >> +	.map_voltage		= regulator_map_voltage_linear_range,
> >> +};
> >> +
> >> +static const struct regulator_desc regulators[] = {
> >> +	TPS68470_REGULATOR(CORE, TPS68470_CORE, tps68470_regulator_ops, 43,
> >> +			   TPS68470_REG_VDVAL, TPS68470_VDVAL_DVOLT_MASK,
> >> +			   TPS68470_REG_VDCTL, TPS68470_VDCTL_EN_MASK,
> >> +			   tps68470_core_ranges, ARRAY_SIZE(tps68470_core_ranges)),
> >> +	TPS68470_REGULATOR(ANA, TPS68470_ANA, tps68470_regulator_ops, 126,
> >> +			   TPS68470_REG_VAVAL, TPS68470_VAVAL_AVOLT_MASK,
> >> +			   TPS68470_REG_VACTL, TPS68470_VACTL_EN_MASK,
> >> +			   tps68470_ldo_ranges, ARRAY_SIZE(tps68470_ldo_ranges)),
> >> +	TPS68470_REGULATOR(VCM, TPS68470_VCM, tps68470_regulator_ops, 126,
> >> +			   TPS68470_REG_VCMVAL, TPS68470_VCMVAL_VCVOLT_MASK,
> >> +			   TPS68470_REG_VCMCTL, TPS68470_VCMCTL_EN_MASK,
> >> +			   tps68470_ldo_ranges, ARRAY_SIZE(tps68470_ldo_ranges)),
> >> +	TPS68470_REGULATOR(VIO, TPS68470_VIO, tps68470_always_on_reg_ops, 126,
> >> +			   TPS68470_REG_VIOVAL, TPS68470_VIOVAL_IOVOLT_MASK,
> >> +			   0, 0,
> >> +			   tps68470_ldo_ranges, ARRAY_SIZE(tps68470_ldo_ranges)),
> >> +/*
> >> + * (1) This regulator must have the same voltage as VIO if S_IO LDO is used to
> >> + *     power a sensor/VCM which I2C is daisy chained behind the PMIC.
> >> + * (2) If there is no I2C daisy chain it can be set freely.
> >> + */
> > 
> > Do we need safety checks for this ?
> 
> There really is no way to deal this condition needs to matches inside the driver,
> this should be enforced by setting proper constraints on the 2 regulators where
> the PMIC is used with a sensor I2C daisy chained behind it.

Right. I tend to be cautious here, as incorrect settings can destroy the
hardware. We should err on the side of too many safety checks rather
than too few. I was thinking that the cio2-bridge driver could set a
daisy-chaining flag, which could trigger additional checks here, but it
wouldn't protect against someone experimenting to support a new device
and setting different voltages without the daisy-chaining flag.

My biggest worry is that someone with an unsupported machine may start
by copying and pasting an existing configuration to try it out, and fry
their hardware.

> >> +	TPS68470_REGULATOR(VSIO, TPS68470_VSIO, tps68470_regulator_ops, 126,
> >> +			   TPS68470_REG_VSIOVAL, TPS68470_VSIOVAL_IOVOLT_MASK,
> >> +			   TPS68470_REG_S_I2C_CTL, TPS68470_S_I2C_CTL_EN_MASK,
> >> +			   tps68470_ldo_ranges, ARRAY_SIZE(tps68470_ldo_ranges)),
> >> +	TPS68470_REGULATOR(AUX1, TPS68470_AUX1, tps68470_regulator_ops, 126,
> >> +			   TPS68470_REG_VAUX1VAL, TPS68470_VAUX1VAL_AUX1VOLT_MASK,
> >> +			   TPS68470_REG_VAUX1CTL, TPS68470_VAUX1CTL_EN_MASK,
> >> +			   tps68470_ldo_ranges, ARRAY_SIZE(tps68470_ldo_ranges)),
> >> +	TPS68470_REGULATOR(AUX2, TPS68470_AUX2, tps68470_regulator_ops, 126,
> >> +			   TPS68470_REG_VAUX2VAL, TPS68470_VAUX2VAL_AUX2VOLT_MASK,
> >> +			   TPS68470_REG_VAUX2CTL, TPS68470_VAUX2CTL_EN_MASK,
> >> +			   tps68470_ldo_ranges, ARRAY_SIZE(tps68470_ldo_ranges)),
> >> +};
> >> +
> >> +static int tps68470_regulator_probe(struct platform_device *pdev)
> >> +{
> >> +	struct device *dev = &pdev->dev;
> >> +	struct tps68470_regulator_platform_data *pdata = dev_get_platdata(dev);
> >> +	struct tps68470_regulator_data *data;
> >> +	struct regulator_config config = { };
> >> +	struct regulator_dev *rdev;
> >> +	int i;
> >> +
> >> +	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> >> +	if (!data)
> >> +		return -ENOMEM;
> >> +
> >> +	data->clk = devm_clk_get(dev, "tps68470-clk");
> >> +	if (IS_ERR(data->clk))
> >> +		return dev_err_probe(dev, PTR_ERR(data->clk), "getting tps68470-clk\n");
> >> +
> >> +	config.dev = dev->parent;
> >> +	config.regmap = dev_get_drvdata(dev->parent);
> >> +	config.driver_data = data;
> >> +
> >> +	for (i = 0; i < TPS68470_NUM_REGULATORS; i++) {
> >> +		if (pdata)
> >> +			config.init_data = pdata->reg_init_data[i];
> >> +		else
> >> +			config.init_data = NULL;
> >> +
> >> +		rdev = devm_regulator_register(dev, &regulators[i], &config);
> >> +		if (IS_ERR(rdev))
> >> +			return dev_err_probe(dev, PTR_ERR(data->clk),
> > 
> > This should be PTR_ERR(rdev).
> 
> Good catch, thanks. Fixed for v7.
> 
> >> +					     "registering %s regulator\n",
> >> +					     regulators[i].name);
> >> +	}
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static struct platform_driver tps68470_regulator_driver = {
> >> +	.driver = {
> >> +		.name = "tps68470-regulator",
> >> +	},
> >> +	.probe = tps68470_regulator_probe,
> >> +};
> >> +
> >> +/*
> >> + * The ACPI tps68470 probe-ordering depends on the clk/gpio/regulator drivers
> >> + * registering before the drivers for the camera-sensors which use them bind.
> >> + * subsys_initcall() ensures this when the drivers are builtin.
> >> + */
> >> +static int __init tps68470_regulator_init(void)
> >> +{
> >> +	return platform_driver_register(&tps68470_regulator_driver);
> >> +}
> >> +subsys_initcall(tps68470_regulator_init);
> >> +
> >> +static void __exit tps68470_regulator_exit(void)
> >> +{
> >> +	platform_driver_unregister(&tps68470_regulator_driver);
> >> +}
> >> +module_exit(tps68470_regulator_exit);
> >> +
> >> +MODULE_ALIAS("platform:tps68470-regulator");
> >> +MODULE_DESCRIPTION("TPS68470 voltage regulator driver");
> >> +MODULE_LICENSE("GPL v2");

-- 
Regards,

Laurent Pinchart