1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Driver for Broadcom BCM2835 SoC temperature sensor
4  *
5  * Copyright (C) 2016 Martin Sperl
6  */
7 
8 #include <linux/clk.h>
9 #include <linux/debugfs.h>
10 #include <linux/device.h>
11 #include <linux/err.h>
12 #include <linux/io.h>
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/of.h>
16 #include <linux/of_address.h>
17 #include <linux/of_device.h>
18 #include <linux/platform_device.h>
19 #include <linux/thermal.h>
20 
21 #include "../thermal_hwmon.h"
22 
23 #define BCM2835_TS_TSENSCTL			0x00
24 #define BCM2835_TS_TSENSSTAT			0x04
25 
26 #define BCM2835_TS_TSENSCTL_PRWDW		BIT(0)
27 #define BCM2835_TS_TSENSCTL_RSTB		BIT(1)
28 
29 /*
30  * bandgap reference voltage in 6 mV increments
31  * 000b = 1178 mV, 001b = 1184 mV, ... 111b = 1220 mV
32  */
33 #define BCM2835_TS_TSENSCTL_CTRL_BITS		3
34 #define BCM2835_TS_TSENSCTL_CTRL_SHIFT		2
35 #define BCM2835_TS_TSENSCTL_CTRL_MASK		    \
36 	GENMASK(BCM2835_TS_TSENSCTL_CTRL_BITS +     \
37 		BCM2835_TS_TSENSCTL_CTRL_SHIFT - 1, \
38 		BCM2835_TS_TSENSCTL_CTRL_SHIFT)
39 #define BCM2835_TS_TSENSCTL_CTRL_DEFAULT	1
40 #define BCM2835_TS_TSENSCTL_EN_INT		BIT(5)
41 #define BCM2835_TS_TSENSCTL_DIRECT		BIT(6)
42 #define BCM2835_TS_TSENSCTL_CLR_INT		BIT(7)
43 #define BCM2835_TS_TSENSCTL_THOLD_SHIFT		8
44 #define BCM2835_TS_TSENSCTL_THOLD_BITS		10
45 #define BCM2835_TS_TSENSCTL_THOLD_MASK		     \
46 	GENMASK(BCM2835_TS_TSENSCTL_THOLD_BITS +     \
47 		BCM2835_TS_TSENSCTL_THOLD_SHIFT - 1, \
48 		BCM2835_TS_TSENSCTL_THOLD_SHIFT)
49 /*
50  * time how long the block to be asserted in reset
51  * which based on a clock counter (TSENS clock assumed)
52  */
53 #define BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT	18
54 #define BCM2835_TS_TSENSCTL_RSTDELAY_BITS	8
55 #define BCM2835_TS_TSENSCTL_REGULEN		BIT(26)
56 
57 #define BCM2835_TS_TSENSSTAT_DATA_BITS		10
58 #define BCM2835_TS_TSENSSTAT_DATA_SHIFT		0
59 #define BCM2835_TS_TSENSSTAT_DATA_MASK		     \
60 	GENMASK(BCM2835_TS_TSENSSTAT_DATA_BITS +     \
61 		BCM2835_TS_TSENSSTAT_DATA_SHIFT - 1, \
62 		BCM2835_TS_TSENSSTAT_DATA_SHIFT)
63 #define BCM2835_TS_TSENSSTAT_VALID		BIT(10)
64 #define BCM2835_TS_TSENSSTAT_INTERRUPT		BIT(11)
65 
66 struct bcm2835_thermal_data {
67 	struct thermal_zone_device *tz;
68 	void __iomem *regs;
69 	struct clk *clk;
70 	struct dentry *debugfsdir;
71 };
72 
73 static int bcm2835_thermal_adc2temp(u32 adc, int offset, int slope)
74 {
75 	return offset + slope * adc;
76 }
77 
78 static int bcm2835_thermal_temp2adc(int temp, int offset, int slope)
79 {
80 	temp -= offset;
81 	temp /= slope;
82 
83 	if (temp < 0)
84 		temp = 0;
85 	if (temp >= BIT(BCM2835_TS_TSENSSTAT_DATA_BITS))
86 		temp = BIT(BCM2835_TS_TSENSSTAT_DATA_BITS) - 1;
87 
88 	return temp;
89 }
90 
91 static int bcm2835_thermal_get_temp(struct thermal_zone_device *tz, int *temp)
92 {
93 	struct bcm2835_thermal_data *data = thermal_zone_device_priv(tz);
94 	u32 val = readl(data->regs + BCM2835_TS_TSENSSTAT);
95 
96 	if (!(val & BCM2835_TS_TSENSSTAT_VALID))
97 		return -EIO;
98 
99 	val &= BCM2835_TS_TSENSSTAT_DATA_MASK;
100 
101 	*temp = bcm2835_thermal_adc2temp(
102 		val,
103 		thermal_zone_get_offset(data->tz),
104 		thermal_zone_get_slope(data->tz));
105 
106 	return 0;
107 }
108 
109 static const struct debugfs_reg32 bcm2835_thermal_regs[] = {
110 	{
111 		.name = "ctl",
112 		.offset = 0
113 	},
114 	{
115 		.name = "stat",
116 		.offset = 4
117 	}
118 };
119 
120 static void bcm2835_thermal_debugfs(struct platform_device *pdev)
121 {
122 	struct bcm2835_thermal_data *data = platform_get_drvdata(pdev);
123 	struct debugfs_regset32 *regset;
124 
125 	data->debugfsdir = debugfs_create_dir("bcm2835_thermal", NULL);
126 
127 	regset = devm_kzalloc(&pdev->dev, sizeof(*regset), GFP_KERNEL);
128 	if (!regset)
129 		return;
130 
131 	regset->regs = bcm2835_thermal_regs;
132 	regset->nregs = ARRAY_SIZE(bcm2835_thermal_regs);
133 	regset->base = data->regs;
134 
135 	debugfs_create_regset32("regset", 0444, data->debugfsdir, regset);
136 }
137 
138 static const struct thermal_zone_device_ops bcm2835_thermal_ops = {
139 	.get_temp = bcm2835_thermal_get_temp,
140 };
141 
142 /*
143  * Note: as per Raspberry Foundation FAQ
144  * (https://www.raspberrypi.org/help/faqs/#performanceOperatingTemperature)
145  * the recommended temperature range for the SoC -40C to +85C
146  * so the trip limit is set to 80C.
147  * this applies to all the BCM283X SoC
148  */
149 
150 static const struct of_device_id bcm2835_thermal_of_match_table[] = {
151 	{
152 		.compatible = "brcm,bcm2835-thermal",
153 	},
154 	{
155 		.compatible = "brcm,bcm2836-thermal",
156 	},
157 	{
158 		.compatible = "brcm,bcm2837-thermal",
159 	},
160 	{},
161 };
162 MODULE_DEVICE_TABLE(of, bcm2835_thermal_of_match_table);
163 
164 static int bcm2835_thermal_probe(struct platform_device *pdev)
165 {
166 	const struct of_device_id *match;
167 	struct thermal_zone_device *tz;
168 	struct bcm2835_thermal_data *data;
169 	int err = 0;
170 	u32 val;
171 	unsigned long rate;
172 
173 	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
174 	if (!data)
175 		return -ENOMEM;
176 
177 	match = of_match_device(bcm2835_thermal_of_match_table,
178 				&pdev->dev);
179 	if (!match)
180 		return -EINVAL;
181 
182 	data->regs = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
183 	if (IS_ERR(data->regs)) {
184 		err = PTR_ERR(data->regs);
185 		return err;
186 	}
187 
188 	data->clk = devm_clk_get_enabled(&pdev->dev, NULL);
189 	if (IS_ERR(data->clk)) {
190 		err = PTR_ERR(data->clk);
191 		if (err != -EPROBE_DEFER)
192 			dev_err(&pdev->dev, "Could not get clk: %d\n", err);
193 		return err;
194 	}
195 
196 	rate = clk_get_rate(data->clk);
197 	if ((rate < 1920000) || (rate > 5000000))
198 		dev_warn(&pdev->dev,
199 			 "Clock %pCn running at %lu Hz is outside of the recommended range: 1.92 to 5MHz\n",
200 			 data->clk, rate);
201 
202 	/* register of thermal sensor and get info from DT */
203 	tz = devm_thermal_of_zone_register(&pdev->dev, 0, data,
204 					   &bcm2835_thermal_ops);
205 	if (IS_ERR(tz)) {
206 		err = PTR_ERR(tz);
207 		dev_err(&pdev->dev,
208 			"Failed to register the thermal device: %d\n",
209 			err);
210 		return err;
211 	}
212 
213 	/*
214 	 * right now the FW does set up the HW-block, so we are not
215 	 * touching the configuration registers.
216 	 * But if the HW is not enabled, then set it up
217 	 * using "sane" values used by the firmware right now.
218 	 */
219 	val = readl(data->regs + BCM2835_TS_TSENSCTL);
220 	if (!(val & BCM2835_TS_TSENSCTL_RSTB)) {
221 		struct thermal_trip trip;
222 		int offset, slope;
223 
224 		slope = thermal_zone_get_slope(tz);
225 		offset = thermal_zone_get_offset(tz);
226 		/*
227 		 * For now we deal only with critical, otherwise
228 		 * would need to iterate
229 		 */
230 		err = thermal_zone_get_trip(tz, 0, &trip);
231 		if (err < 0) {
232 			dev_err(&pdev->dev,
233 				"Not able to read trip_temp: %d\n",
234 				err);
235 			return err;
236 		}
237 
238 		/* set bandgap reference voltage and enable voltage regulator */
239 		val = (BCM2835_TS_TSENSCTL_CTRL_DEFAULT <<
240 		       BCM2835_TS_TSENSCTL_CTRL_SHIFT) |
241 		      BCM2835_TS_TSENSCTL_REGULEN;
242 
243 		/* use the recommended reset duration */
244 		val |= (0xFE << BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT);
245 
246 		/*  trip_adc value from info */
247 		val |= bcm2835_thermal_temp2adc(trip.temperature,
248 						offset,
249 						slope)
250 			<< BCM2835_TS_TSENSCTL_THOLD_SHIFT;
251 
252 		/* write the value back to the register as 2 steps */
253 		writel(val, data->regs + BCM2835_TS_TSENSCTL);
254 		val |= BCM2835_TS_TSENSCTL_RSTB;
255 		writel(val, data->regs + BCM2835_TS_TSENSCTL);
256 	}
257 
258 	data->tz = tz;
259 
260 	platform_set_drvdata(pdev, data);
261 
262 	/*
263 	 * Thermal_zone doesn't enable hwmon as default,
264 	 * enable it here
265 	 */
266 	err = thermal_add_hwmon_sysfs(tz);
267 	if (err)
268 		return err;
269 
270 	bcm2835_thermal_debugfs(pdev);
271 
272 	return 0;
273 }
274 
275 static void bcm2835_thermal_remove(struct platform_device *pdev)
276 {
277 	struct bcm2835_thermal_data *data = platform_get_drvdata(pdev);
278 
279 	debugfs_remove_recursive(data->debugfsdir);
280 }
281 
282 static struct platform_driver bcm2835_thermal_driver = {
283 	.probe = bcm2835_thermal_probe,
284 	.remove_new = bcm2835_thermal_remove,
285 	.driver = {
286 		.name = "bcm2835_thermal",
287 		.of_match_table = bcm2835_thermal_of_match_table,
288 	},
289 };
290 module_platform_driver(bcm2835_thermal_driver);
291 
292 MODULE_AUTHOR("Martin Sperl");
293 MODULE_DESCRIPTION("Thermal driver for bcm2835 chip");
294 MODULE_LICENSE("GPL");
295