forked from rrcarlosr/Jetpack
110 lines
2.7 KiB
C
110 lines
2.7 KiB
C
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/*
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* Copyright (c) 2017, NVIDIA CORPORATION. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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*/
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/err.h>
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#include <linux/pwm.h>
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#include <linux/hwmon.h>
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#include <linux/hwmon-sysfs.h>
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struct pwm_hwmon_tach {
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struct device *dev;
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struct pwm_device *pwm;
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struct device *hwmon;
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};
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static ssize_t show_rpm(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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struct pwm_hwmon_tach *ptt = dev_get_drvdata(dev);
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struct pwm_device *pwm = ptt->pwm;
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struct pwm_capture result;
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unsigned int rpm = 0;
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int ret;
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ret = pwm_capture(pwm, &result, 0);
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if (ret < 0) {
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dev_err(ptt->dev, "Failed to capture PWM: %d\n", ret);
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return ret;
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}
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if (result.period)
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rpm = DIV_ROUND_CLOSEST_ULL(60ULL * NSEC_PER_SEC,
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result.period);
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return sprintf(buf, "%u\n", rpm);
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}
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static SENSOR_DEVICE_ATTR(rpm, 0444, show_rpm, NULL, 0);
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static struct attribute *pwm_tach_attrs[] = {
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&sensor_dev_attr_rpm.dev_attr.attr,
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NULL,
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};
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ATTRIBUTE_GROUPS(pwm_tach);
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static int pwm_tach_probe(struct platform_device *pdev)
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{
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struct pwm_hwmon_tach *ptt;
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ptt = devm_kzalloc(&pdev->dev, sizeof(*ptt), GFP_KERNEL);
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if (!ptt)
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return -ENOMEM;
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ptt->dev = &pdev->dev;
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platform_set_drvdata(pdev, ptt);
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dev_set_drvdata(&pdev->dev, ptt);
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ptt->pwm = devm_of_pwm_get(&pdev->dev, pdev->dev.of_node, NULL);
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if (IS_ERR(ptt->pwm)) {
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dev_err(&pdev->dev, "Failed to get pwm: %ld\n",
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PTR_ERR(ptt->pwm));
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return PTR_ERR(ptt->pwm);
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}
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ptt->hwmon = devm_hwmon_device_register_with_groups(&pdev->dev,
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"pwm_tach", ptt, pwm_tach_groups);
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if (IS_ERR(ptt->hwmon)) {
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dev_err(&pdev->dev, "Failed to register hwmon device: %d\n",
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PTR_ERR_OR_ZERO(ptt->hwmon));
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return PTR_ERR_OR_ZERO(ptt->hwmon);
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}
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return 0;
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}
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static const struct of_device_id pwm_tach_of_match[] = {
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{ .compatible = "generic-pwm-tachometer" },
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{}
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};
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MODULE_DEVICE_TABLE(of, tach_of_match);
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static struct platform_driver pwm_tach_driver = {
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.driver = {
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.name = "generic-pwm-tachometer",
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.of_match_table = pwm_tach_of_match,
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},
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.probe = pwm_tach_probe,
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};
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module_platform_driver(pwm_tach_driver);
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MODULE_DESCRIPTION("PWM based Generic Tachometer driver");
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MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
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MODULE_AUTHOR("R Raj Kumar <rrajk@nvidia.com>");
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MODULE_LICENSE("GPL v2");
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