2019-05-27 14:55:01 +08:00
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// SPDX-License-Identifier: GPL-2.0-or-later
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2010-02-12 18:18:08 +08:00
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/*
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* dummy.c
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*
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* Copyright 2010 Wolfson Microelectronics PLC.
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*
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* Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
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*
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* This is useful for systems with mixed controllable and
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* non-controllable regulators, as well as for allowing testing on
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* systems with no controllable regulators.
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*/
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#include <linux/err.h>
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2011-07-18 03:48:22 +08:00
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#include <linux/export.h>
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2010-02-12 18:18:08 +08:00
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#include <linux/platform_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 "dummy.h"
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struct regulator_dev *dummy_regulator_rdev;
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2020-09-13 16:41:10 +08:00
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static const struct regulator_init_data dummy_initdata = {
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2014-02-25 18:03:46 +08:00
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.constraints = {
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.always_on = 1,
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},
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};
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2010-02-12 18:18:08 +08:00
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2020-09-13 16:41:10 +08:00
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static const struct regulator_ops dummy_ops;
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2010-02-12 18:18:08 +08:00
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2014-10-27 23:44:11 +08:00
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static const struct regulator_desc dummy_desc = {
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2012-08-08 03:01:37 +08:00
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.name = "regulator-dummy",
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2010-02-12 18:18:08 +08:00
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.id = -1,
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.type = REGULATOR_VOLTAGE,
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.owner = THIS_MODULE,
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.ops = &dummy_ops,
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};
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2012-11-20 02:22:22 +08:00
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static int dummy_regulator_probe(struct platform_device *pdev)
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2011-06-08 06:36:18 +08:00
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{
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2012-04-04 07:50:22 +08:00
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struct regulator_config config = { };
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2011-06-08 06:36:18 +08:00
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int ret;
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2012-05-09 01:08:43 +08:00
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config.dev = &pdev->dev;
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2012-04-04 07:50:22 +08:00
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config.init_data = &dummy_initdata;
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2021-09-25 11:55:07 +08:00
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dummy_regulator_rdev = devm_regulator_register(&pdev->dev, &dummy_desc,
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&config);
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2011-06-08 06:36:18 +08:00
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if (IS_ERR(dummy_regulator_rdev)) {
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ret = PTR_ERR(dummy_regulator_rdev);
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pr_err("Failed to register regulator: %d\n", ret);
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return ret;
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}
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return 0;
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}
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static struct platform_driver dummy_regulator_driver = {
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.probe = dummy_regulator_probe,
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.driver = {
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.name = "reg-dummy",
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regulator: Set PROBE_PREFER_ASYNCHRONOUS for drivers that existed in 4.14
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>
2023-03-17 03:54:38 +08:00
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.probe_type = PROBE_PREFER_ASYNCHRONOUS,
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2011-06-08 06:36:18 +08:00
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},
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};
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2010-02-12 18:18:08 +08:00
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static struct platform_device *dummy_pdev;
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void __init regulator_dummy_init(void)
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{
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int ret;
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dummy_pdev = platform_device_alloc("reg-dummy", -1);
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if (!dummy_pdev) {
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pr_err("Failed to allocate dummy regulator device\n");
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return;
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}
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ret = platform_device_add(dummy_pdev);
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if (ret != 0) {
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pr_err("Failed to register dummy regulator device: %d\n", ret);
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platform_device_put(dummy_pdev);
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return;
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}
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2011-06-08 06:36:18 +08:00
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ret = platform_driver_register(&dummy_regulator_driver);
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if (ret != 0) {
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pr_err("Failed to register dummy regulator driver: %d\n", ret);
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2010-02-12 18:18:08 +08:00
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platform_device_unregister(dummy_pdev);
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}
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}
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