1// SPDX-License-Identifier: GPL-2.0-or-later
  2/* Lantiq cpu temperature sensor driver
  3 *
  4 * Copyright (C) 2017 Florian Eckert <fe@dev.tdt.de>
  5 */
  6
  7#include <linux/bitops.h>
  8#include <linux/delay.h>
  9#include <linux/hwmon.h>
 10#include <linux/hwmon-sysfs.h>
 11#include <linux/init.h>
 12#include <linux/mod_devicetable.h>
 13#include <linux/module.h>
 14#include <linux/platform_device.h>
 15
 16#include <lantiq_soc.h>
 17
 18/* gphy1 configuration register contains cpu temperature */
 19#define CGU_GPHY1_CR   0x0040
 20#define CGU_TEMP_PD    BIT(19)
 21
 22static void ltq_cputemp_enable(void)
 23{
 24	ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) | CGU_TEMP_PD, CGU_GPHY1_CR);
 25}
 26
 27static void ltq_cputemp_disable(void *data)
 28{
 29	ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) & ~CGU_TEMP_PD, CGU_GPHY1_CR);
 30}
 31
 32static int ltq_read(struct device *dev, enum hwmon_sensor_types type,
 33		    u32 attr, int channel, long *temp)
 34{
 35	int value;
 36
 37	switch (attr) {
 38	case hwmon_temp_input:
 39		/* get the temperature including one decimal place */
 40		value = (ltq_cgu_r32(CGU_GPHY1_CR) >> 9) & 0x01FF;
 41		value = value * 5;
 42		/* range -38 to +154 °C, register value zero is -38.0 °C */
 43		value -= 380;
 44		/* scale temp to millidegree */
 45		value = value * 100;
 46		break;
 47	default:
 48		return -EOPNOTSUPP;
 49	}
 50
 51	*temp = value;
 52	return 0;
 53}
 54
 55static umode_t ltq_is_visible(const void *_data, enum hwmon_sensor_types type,
 56			      u32 attr, int channel)
 57{
 58	if (type != hwmon_temp)
 59		return 0;
 60
 61	switch (attr) {
 62	case hwmon_temp_input:
 63		return 0444;
 64	default:
 65		return 0;
 66	}
 67}
 68
 69static const struct hwmon_channel_info * const ltq_info[] = {
 70	HWMON_CHANNEL_INFO(chip,
 71			   HWMON_C_REGISTER_TZ),
 72	HWMON_CHANNEL_INFO(temp,
 73			   HWMON_T_INPUT),
 74	NULL
 75};
 76
 77static const struct hwmon_ops ltq_hwmon_ops = {
 78	.is_visible = ltq_is_visible,
 79	.read = ltq_read,
 80};
 81
 82static const struct hwmon_chip_info ltq_chip_info = {
 83	.ops = &ltq_hwmon_ops,
 84	.info = ltq_info,
 85};
 86
 87static int ltq_cputemp_probe(struct platform_device *pdev)
 88{
 89	struct device *hwmon_dev;
 90	int err = 0;
 91
 92	/* available on vr9 v1.2 SoCs only */
 93	if (ltq_soc_type() != SOC_TYPE_VR9_2)
 94		return -ENODEV;
 95
 96	err = devm_add_action(&pdev->dev, ltq_cputemp_disable, NULL);
 97	if (err)
 98		return err;
 99
100	ltq_cputemp_enable();
101
102	hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
103							 "ltq_cputemp",
104							 NULL,
105							 &ltq_chip_info,
106							 NULL);
107
108	if (IS_ERR(hwmon_dev)) {
109		dev_err(&pdev->dev, "Failed to register as hwmon device");
110		return PTR_ERR(hwmon_dev);
111	}
112
113	return 0;
114}
115
116const struct of_device_id ltq_cputemp_match[] = {
117	{ .compatible = "lantiq,cputemp" },
118	{},
119};
120MODULE_DEVICE_TABLE(of, ltq_cputemp_match);
121
122static struct platform_driver ltq_cputemp_driver = {
123	.probe = ltq_cputemp_probe,
124	.driver = {
125		.name = "ltq-cputemp",
126		.of_match_table = ltq_cputemp_match,
127	},
128};
129
130module_platform_driver(ltq_cputemp_driver);
131
132MODULE_AUTHOR("Florian Eckert <fe@dev.tdt.de>");
133MODULE_DESCRIPTION("Lantiq cpu temperature sensor driver");
134MODULE_LICENSE("GPL");