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