259b93b21a
Probing of regulators can be a slow operation and can contribute to slower boot times. This is especially true if a regulator is turned on at probe time (with regulator-boot-on or regulator-always-on) and the regulator requires delays (off-on-time, ramp time, etc). While the overall kernel is not ready to switch to async probe by default, as per the discussion on the mailing lists [1] it is believed that the regulator subsystem is in good shape and we can move regulator drivers over wholesale. There is no way to just magically opt in all regulators (regulators are just normal drivers like platform_driver), so we set PROBE_PREFER_ASYNCHRONOUS for all regulators found in 'drivers/regulator' individually. Given the number of drivers touched and the impossibility to test this ahead of time, it wouldn't be shocking at all if this caused a regression for someone. If there is a regression caused by this patch, it's likely to be one of the cases talked about in [1]. As a "quick fix", drivers involved in the regression could be fixed by changing them to PROBE_FORCE_SYNCHRONOUS. That being said, the correct fix would be to directly fix the problem that caused the issue with async probe. The approach here follows a similar approach that was used for the mmc subsystem several years ago [2]. In fact, I ran nearly the same python script to auto-generate the changes. The only thing I changed was to search for "i2c_driver", "spmi_driver", and "spi_driver" in addition to "platform_driver". [1] https://lore.kernel.org/r/06db017f-e985-4434-8d1d-02ca2100cca0@sirena.org.uk [2] https://lore.kernel.org/r/20200903232441.2694866-1-dianders@chromium.org/ Signed-off-by: Douglas Anderson <dianders@chromium.org> Link: https://lore.kernel.org/r/20230316125351.1.I2a4677392a38db5758dee0788b2cea5872562a82@changeid Signed-off-by: Mark Brown <broonie@kernel.org>
102 lines
2.7 KiB
C
102 lines
2.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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//
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// Copyright (C) 2012 ARM Limited
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#define DRVNAME "vexpress-regulator"
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#define pr_fmt(fmt) DRVNAME ": " fmt
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/module.h>
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#include <linux/of_device.h>
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#include <linux/regulator/driver.h>
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#include <linux/regulator/machine.h>
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#include <linux/regulator/of_regulator.h>
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#include <linux/vexpress.h>
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static int vexpress_regulator_get_voltage(struct regulator_dev *regdev)
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{
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unsigned int uV;
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int err = regmap_read(regdev->regmap, 0, &uV);
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return err ? err : uV;
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}
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static int vexpress_regulator_set_voltage(struct regulator_dev *regdev,
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int min_uV, int max_uV, unsigned *selector)
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{
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return regmap_write(regdev->regmap, 0, min_uV);
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}
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static const struct regulator_ops vexpress_regulator_ops_ro = {
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.get_voltage = vexpress_regulator_get_voltage,
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};
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static const struct regulator_ops vexpress_regulator_ops = {
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.get_voltage = vexpress_regulator_get_voltage,
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.set_voltage = vexpress_regulator_set_voltage,
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};
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static int vexpress_regulator_probe(struct platform_device *pdev)
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{
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struct regulator_desc *desc;
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struct regulator_init_data *init_data;
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struct regulator_config config = { };
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struct regulator_dev *rdev;
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struct regmap *regmap;
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desc = devm_kzalloc(&pdev->dev, sizeof(*desc), GFP_KERNEL);
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if (!desc)
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return -ENOMEM;
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regmap = devm_regmap_init_vexpress_config(&pdev->dev);
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if (IS_ERR(regmap))
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return PTR_ERR(regmap);
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desc->name = dev_name(&pdev->dev);
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desc->type = REGULATOR_VOLTAGE;
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desc->owner = THIS_MODULE;
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desc->continuous_voltage_range = true;
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init_data = of_get_regulator_init_data(&pdev->dev, pdev->dev.of_node,
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desc);
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if (!init_data)
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return -EINVAL;
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init_data->constraints.apply_uV = 0;
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if (init_data->constraints.min_uV && init_data->constraints.max_uV)
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desc->ops = &vexpress_regulator_ops;
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else
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desc->ops = &vexpress_regulator_ops_ro;
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config.regmap = regmap;
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config.dev = &pdev->dev;
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config.init_data = init_data;
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config.of_node = pdev->dev.of_node;
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rdev = devm_regulator_register(&pdev->dev, desc, &config);
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return PTR_ERR_OR_ZERO(rdev);
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}
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static const struct of_device_id vexpress_regulator_of_match[] = {
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{ .compatible = "arm,vexpress-volt", },
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{ }
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};
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MODULE_DEVICE_TABLE(of, vexpress_regulator_of_match);
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static struct platform_driver vexpress_regulator_driver = {
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.probe = vexpress_regulator_probe,
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.driver = {
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.name = DRVNAME,
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.probe_type = PROBE_PREFER_ASYNCHRONOUS,
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.of_match_table = vexpress_regulator_of_match,
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},
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};
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module_platform_driver(vexpress_regulator_driver);
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MODULE_AUTHOR("Pawel Moll <pawel.moll@arm.com>");
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MODULE_DESCRIPTION("Versatile Express regulator");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:vexpress-regulator");
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