xref: /openbmc/linux/drivers/hwmon/sparx5-temp.c (revision dc881144)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Sparx5 SoC temperature sensor driver
3  *
4  * Copyright (C) 2020 Lars Povlsen <lars.povlsen@microchip.com>
5  */
6 
7 #include <linux/bitfield.h>
8 #include <linux/clk.h>
9 #include <linux/hwmon.h>
10 #include <linux/init.h>
11 #include <linux/io.h>
12 #include <linux/mod_devicetable.h>
13 #include <linux/module.h>
14 #include <linux/platform_device.h>
15 
16 #define TEMP_CTRL		0
17 #define TEMP_CFG		4
18 #define  TEMP_CFG_CYCLES	GENMASK(24, 15)
19 #define  TEMP_CFG_ENA		BIT(0)
20 #define TEMP_STAT		8
21 #define  TEMP_STAT_VALID	BIT(12)
22 #define  TEMP_STAT_TEMP		GENMASK(11, 0)
23 
24 struct s5_hwmon {
25 	void __iomem *base;
26 	struct clk *clk;
27 };
28 
s5_temp_enable(struct s5_hwmon * hwmon)29 static void s5_temp_enable(struct s5_hwmon *hwmon)
30 {
31 	u32 val = readl(hwmon->base + TEMP_CFG);
32 	u32 clk = clk_get_rate(hwmon->clk) / USEC_PER_SEC;
33 
34 	val &= ~TEMP_CFG_CYCLES;
35 	val |= FIELD_PREP(TEMP_CFG_CYCLES, clk);
36 	val |= TEMP_CFG_ENA;
37 
38 	writel(val, hwmon->base + TEMP_CFG);
39 }
40 
s5_read(struct device * dev,enum hwmon_sensor_types type,u32 attr,int channel,long * temp)41 static int s5_read(struct device *dev, enum hwmon_sensor_types type,
42 		   u32 attr, int channel, long *temp)
43 {
44 	struct s5_hwmon *hwmon = dev_get_drvdata(dev);
45 	int rc = 0, value;
46 	u32 stat;
47 
48 	switch (attr) {
49 	case hwmon_temp_input:
50 		stat = readl_relaxed(hwmon->base + TEMP_STAT);
51 		if (!(stat & TEMP_STAT_VALID))
52 			return -EAGAIN;
53 		value = stat & TEMP_STAT_TEMP;
54 		/*
55 		 * From register documentation:
56 		 * Temp(C) = TEMP_SENSOR_STAT.TEMP / 4096 * 352.2 - 109.4
57 		 */
58 		value = DIV_ROUND_CLOSEST(value * 3522, 4096) - 1094;
59 		/*
60 		 * Scale down by 10 from above and multiply by 1000 to
61 		 * have millidegrees as specified by the hwmon sysfs
62 		 * interface.
63 		 */
64 		value *= 100;
65 		*temp = value;
66 		break;
67 	default:
68 		rc = -EOPNOTSUPP;
69 		break;
70 	}
71 
72 	return rc;
73 }
74 
s5_is_visible(const void * _data,enum hwmon_sensor_types type,u32 attr,int channel)75 static umode_t s5_is_visible(const void *_data, enum hwmon_sensor_types type,
76 			     u32 attr, int channel)
77 {
78 	if (type != hwmon_temp)
79 		return 0;
80 
81 	switch (attr) {
82 	case hwmon_temp_input:
83 		return 0444;
84 	default:
85 		return 0;
86 	}
87 }
88 
89 static const struct hwmon_channel_info * const s5_info[] = {
90 	HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
91 	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
92 	NULL
93 };
94 
95 static const struct hwmon_ops s5_hwmon_ops = {
96 	.is_visible = s5_is_visible,
97 	.read = s5_read,
98 };
99 
100 static const struct hwmon_chip_info s5_chip_info = {
101 	.ops = &s5_hwmon_ops,
102 	.info = s5_info,
103 };
104 
s5_temp_probe(struct platform_device * pdev)105 static int s5_temp_probe(struct platform_device *pdev)
106 {
107 	struct device *hwmon_dev;
108 	struct s5_hwmon *hwmon;
109 
110 	hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
111 	if (!hwmon)
112 		return -ENOMEM;
113 
114 	hwmon->base = devm_platform_ioremap_resource(pdev, 0);
115 	if (IS_ERR(hwmon->base))
116 		return PTR_ERR(hwmon->base);
117 
118 	hwmon->clk = devm_clk_get_enabled(&pdev->dev, NULL);
119 	if (IS_ERR(hwmon->clk))
120 		return PTR_ERR(hwmon->clk);
121 
122 	s5_temp_enable(hwmon);
123 
124 	hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
125 							 "s5_temp",
126 							 hwmon,
127 							 &s5_chip_info,
128 							 NULL);
129 
130 	return PTR_ERR_OR_ZERO(hwmon_dev);
131 }
132 
133 static const struct of_device_id s5_temp_match[] = {
134 	{ .compatible = "microchip,sparx5-temp" },
135 	{},
136 };
137 MODULE_DEVICE_TABLE(of, s5_temp_match);
138 
139 static struct platform_driver s5_temp_driver = {
140 	.probe = s5_temp_probe,
141 	.driver = {
142 		.name = "sparx5-temp",
143 		.of_match_table = s5_temp_match,
144 	},
145 };
146 
147 module_platform_driver(s5_temp_driver);
148 
149 MODULE_AUTHOR("Lars Povlsen <lars.povlsen@microchip.com>");
150 MODULE_DESCRIPTION("Sparx5 SoC temperature sensor driver");
151 MODULE_LICENSE("GPL");
152