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09c434b8 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
0b58c08b MG |
2 | #include <linux/io.h> |
3 | #include <linux/delay.h> | |
4 | #include <linux/module.h> | |
5 | #include <linux/thermal.h> | |
6 | #include <linux/platform_device.h> | |
7 | ||
8 | /* | |
9 | * According to a data sheet draft, "this temperature sensor uses a bandgap | |
10 | * type of circuit to compare a voltage which has a negative temperature | |
11 | * coefficient with a voltage that is proportional to absolute temperature. | |
12 | * A resistor bank allows 41 different temperature thresholds to be selected | |
13 | * and the logic output will then indicate whether the actual die temperature | |
14 | * lies above or below the selected threshold." | |
15 | */ | |
16 | ||
17 | #define TEMPSI_CMD 0 | |
18 | #define TEMPSI_RES 4 | |
19 | #define TEMPSI_CFG 8 | |
20 | ||
21 | #define CMD_OFF 0 | |
22 | #define CMD_ON 1 | |
23 | #define CMD_READ 2 | |
24 | ||
25 | #define IDX_MIN 15 | |
26 | #define IDX_MAX 40 | |
27 | ||
28 | struct tango_thermal_priv { | |
29 | void __iomem *base; | |
30 | int thresh_idx; | |
31 | }; | |
32 | ||
33 | static bool temp_above_thresh(void __iomem *base, int thresh_idx) | |
34 | { | |
35 | writel(CMD_READ | thresh_idx << 8, base + TEMPSI_CMD); | |
36 | usleep_range(10, 20); | |
37 | writel(CMD_READ | thresh_idx << 8, base + TEMPSI_CMD); | |
38 | ||
39 | return readl(base + TEMPSI_RES); | |
40 | } | |
41 | ||
42 | static int tango_get_temp(void *arg, int *res) | |
43 | { | |
44 | struct tango_thermal_priv *priv = arg; | |
45 | int idx = priv->thresh_idx; | |
46 | ||
47 | if (temp_above_thresh(priv->base, idx)) { | |
48 | /* Search upward by incrementing thresh_idx */ | |
49 | while (idx < IDX_MAX && temp_above_thresh(priv->base, ++idx)) | |
50 | cpu_relax(); | |
51 | idx = idx - 1; /* always return lower bound */ | |
52 | } else { | |
53 | /* Search downward by decrementing thresh_idx */ | |
54 | while (idx > IDX_MIN && !temp_above_thresh(priv->base, --idx)) | |
55 | cpu_relax(); | |
56 | } | |
57 | ||
58 | *res = (idx * 9 / 2 - 38) * 1000; /* millidegrees Celsius */ | |
59 | priv->thresh_idx = idx; | |
60 | ||
61 | return 0; | |
62 | } | |
63 | ||
64 | static const struct thermal_zone_of_device_ops ops = { | |
65 | .get_temp = tango_get_temp, | |
66 | }; | |
67 | ||
9dfe1a2f MG |
68 | static void tango_thermal_init(struct tango_thermal_priv *priv) |
69 | { | |
70 | writel(0, priv->base + TEMPSI_CFG); | |
71 | writel(CMD_ON, priv->base + TEMPSI_CMD); | |
72 | } | |
73 | ||
0b58c08b MG |
74 | static int tango_thermal_probe(struct platform_device *pdev) |
75 | { | |
76 | struct resource *res; | |
77 | struct tango_thermal_priv *priv; | |
78 | struct thermal_zone_device *tzdev; | |
79 | ||
80 | priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); | |
81 | if (!priv) | |
82 | return -ENOMEM; | |
83 | ||
84 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
85 | priv->base = devm_ioremap_resource(&pdev->dev, res); | |
86 | if (IS_ERR(priv->base)) | |
87 | return PTR_ERR(priv->base); | |
88 | ||
9dfe1a2f | 89 | platform_set_drvdata(pdev, priv); |
0b58c08b | 90 | priv->thresh_idx = IDX_MIN; |
9dfe1a2f | 91 | tango_thermal_init(priv); |
0b58c08b MG |
92 | |
93 | tzdev = devm_thermal_zone_of_sensor_register(&pdev->dev, 0, priv, &ops); | |
bba07c13 | 94 | return PTR_ERR_OR_ZERO(tzdev); |
0b58c08b MG |
95 | } |
96 | ||
9dfe1a2f MG |
97 | static int __maybe_unused tango_thermal_resume(struct device *dev) |
98 | { | |
99 | tango_thermal_init(dev_get_drvdata(dev)); | |
100 | return 0; | |
101 | } | |
102 | ||
103 | static SIMPLE_DEV_PM_OPS(tango_thermal_pm, NULL, tango_thermal_resume); | |
104 | ||
0b58c08b MG |
105 | static const struct of_device_id tango_sensor_ids[] = { |
106 | { | |
107 | .compatible = "sigma,smp8758-thermal", | |
108 | }, | |
109 | { /* sentinel */ } | |
110 | }; | |
26d9339d | 111 | MODULE_DEVICE_TABLE(of, tango_sensor_ids); |
0b58c08b MG |
112 | |
113 | static struct platform_driver tango_thermal_driver = { | |
114 | .probe = tango_thermal_probe, | |
115 | .driver = { | |
116 | .name = "tango-thermal", | |
117 | .of_match_table = tango_sensor_ids, | |
9dfe1a2f | 118 | .pm = &tango_thermal_pm, |
0b58c08b MG |
119 | }, |
120 | }; | |
121 | ||
122 | module_platform_driver(tango_thermal_driver); | |
123 | ||
124 | MODULE_LICENSE("GPL"); | |
125 | MODULE_AUTHOR("Sigma Designs"); | |
126 | MODULE_DESCRIPTION("Tango temperature sensor"); |