drivers/pwm/pwm-lpss-platform.c

Source file repositories/reference/linux-study-clean/drivers/pwm/pwm-lpss-platform.c

File Facts

System
Linux kernel
Corpus path
drivers/pwm/pwm-lpss-platform.c
Extension
.c
Size
2534 bytes
Lines
83
Domain
Driver Families
Bucket
drivers/pwm
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Intel Low Power Subsystem PWM controller driver
 *
 * Copyright (C) 2014, Intel Corporation
 *
 * Derived from the original pwm-lpss.c
 */

#include <linux/kernel.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/property.h>

#include "pwm-lpss.h"


static int pwm_lpss_probe_platform(struct platform_device *pdev)
{
	const struct pwm_lpss_boardinfo *info;
	struct pwm_chip *chip;
	void __iomem *base;

	info = device_get_match_data(&pdev->dev);
	if (!info)
		return -ENODEV;

	base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(base))
		return PTR_ERR(base);

	chip = devm_pwm_lpss_probe(&pdev->dev, base, info);
	if (IS_ERR(chip))
		return PTR_ERR(chip);

	/*
	 * On Cherry Trail devices the GFX0._PS0 AML checks if the controller
	 * is on and if it is not on it turns it on and restores what it
	 * believes is the correct state to the PWM controller.
	 * Because of this we must disallow direct-complete, which keeps the
	 * controller (runtime)suspended on resume, to avoid 2 issues:
	 * 1. The controller getting turned on without the linux-pm code
	 *    knowing about this. On devices where the controller is unused
	 *    this causes it to stay on during the next suspend causing high
	 *    battery drain (because S0i3 is not reached)
	 * 2. The state restoring code unexpectedly messing with the controller
	 *
	 * Leaving the controller runtime-suspended (skipping runtime-resume +
	 * normal-suspend) during suspend is fine.
	 */
	if (info->other_devices_aml_touches_pwm_regs)
		dev_pm_set_driver_flags(&pdev->dev, DPM_FLAG_NO_DIRECT_COMPLETE|
						    DPM_FLAG_SMART_SUSPEND);

	pm_runtime_set_active(&pdev->dev);
	return devm_pm_runtime_enable(&pdev->dev);
}

static const struct acpi_device_id pwm_lpss_acpi_match[] = {
	{ "80860F09", (unsigned long)&pwm_lpss_byt_info },
	{ "80862288", (unsigned long)&pwm_lpss_bsw_info },
	{ "80862289", (unsigned long)&pwm_lpss_bsw_info },
	{ "80865AC8", (unsigned long)&pwm_lpss_bxt_info },
	{ },
};
MODULE_DEVICE_TABLE(acpi, pwm_lpss_acpi_match);

static struct platform_driver pwm_lpss_driver_platform = {
	.driver = {
		.name = "pwm-lpss",
		.acpi_match_table = pwm_lpss_acpi_match,
	},
	.probe = pwm_lpss_probe_platform,
};
module_platform_driver(pwm_lpss_driver_platform);

MODULE_DESCRIPTION("PWM platform driver for Intel LPSS");
MODULE_LICENSE("GPL v2");
MODULE_IMPORT_NS("PWM_LPSS");
MODULE_ALIAS("platform:pwm-lpss");

Annotation

Implementation Notes