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(void *d, int *temp)
92 {
93 	struct bcm2835_thermal_data *data = d;
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 thermal_zone_device *tz = platform_get_drvdata(pdev);
123 	struct bcm2835_thermal_data *data = tz->devdata;
124 	struct debugfs_regset32 *regset;
125 
126 	data->debugfsdir = debugfs_create_dir("bcm2835_thermal", NULL);
127 	if (!data->debugfsdir)
128 		return;
129 
130 	regset = devm_kzalloc(&pdev->dev, sizeof(*regset), GFP_KERNEL);
131 	if (!regset)
132 		return;
133 
134 	regset->regs = bcm2835_thermal_regs;
135 	regset->nregs = ARRAY_SIZE(bcm2835_thermal_regs);
136 	regset->base = data->regs;
137 
138 	debugfs_create_regset32("regset", 0444, data->debugfsdir, regset);
139 }
140 
141 static const struct thermal_zone_of_device_ops bcm2835_thermal_ops = {
142 	.get_temp = bcm2835_thermal_get_temp,
143 };
144 
145 /*
146  * Note: as per Raspberry Foundation FAQ
147  * (https://www.raspberrypi.org/help/faqs/#performanceOperatingTemperature)
148  * the recommended temperature range for the SoC -40C to +85C
149  * so the trip limit is set to 80C.
150  * this applies to all the BCM283X SoC
151  */
152 
153 static const struct of_device_id bcm2835_thermal_of_match_table[] = {
154 	{
155 		.compatible = "brcm,bcm2835-thermal",
156 	},
157 	{
158 		.compatible = "brcm,bcm2836-thermal",
159 	},
160 	{
161 		.compatible = "brcm,bcm2837-thermal",
162 	},
163 	{},
164 };
165 MODULE_DEVICE_TABLE(of, bcm2835_thermal_of_match_table);
166 
167 static int bcm2835_thermal_probe(struct platform_device *pdev)
168 {
169 	const struct of_device_id *match;
170 	struct thermal_zone_device *tz;
171 	struct bcm2835_thermal_data *data;
172 	struct resource *res;
173 	int err = 0;
174 	u32 val;
175 	unsigned long rate;
176 
177 	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
178 	if (!data)
179 		return -ENOMEM;
180 
181 	match = of_match_device(bcm2835_thermal_of_match_table,
182 				&pdev->dev);
183 	if (!match)
184 		return -EINVAL;
185 
186 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
187 	data->regs = devm_ioremap_resource(&pdev->dev, res);
188 	if (IS_ERR(data->regs)) {
189 		err = PTR_ERR(data->regs);
190 		dev_err(&pdev->dev, "Could not get registers: %d\n", err);
191 		return err;
192 	}
193 
194 	data->clk = devm_clk_get(&pdev->dev, NULL);
195 	if (IS_ERR(data->clk)) {
196 		err = PTR_ERR(data->clk);
197 		if (err != -EPROBE_DEFER)
198 			dev_err(&pdev->dev, "Could not get clk: %d\n", err);
199 		return err;
200 	}
201 
202 	err = clk_prepare_enable(data->clk);
203 	if (err)
204 		return err;
205 
206 	rate = clk_get_rate(data->clk);
207 	if ((rate < 1920000) || (rate > 5000000))
208 		dev_warn(&pdev->dev,
209 			 "Clock %pCn running at %lu Hz is outside of the recommended range: 1.92 to 5MHz\n",
210 			 data->clk, rate);
211 
212 	/* register of thermal sensor and get info from DT */
213 	tz = thermal_zone_of_sensor_register(&pdev->dev, 0, data,
214 					     &bcm2835_thermal_ops);
215 	if (IS_ERR(tz)) {
216 		err = PTR_ERR(tz);
217 		dev_err(&pdev->dev,
218 			"Failed to register the thermal device: %d\n",
219 			err);
220 		goto err_clk;
221 	}
222 
223 	/*
224 	 * right now the FW does set up the HW-block, so we are not
225 	 * touching the configuration registers.
226 	 * But if the HW is not enabled, then set it up
227 	 * using "sane" values used by the firmware right now.
228 	 */
229 	val = readl(data->regs + BCM2835_TS_TSENSCTL);
230 	if (!(val & BCM2835_TS_TSENSCTL_RSTB)) {
231 		int trip_temp, offset, slope;
232 
233 		slope = thermal_zone_get_slope(tz);
234 		offset = thermal_zone_get_offset(tz);
235 		/*
236 		 * For now we deal only with critical, otherwise
237 		 * would need to iterate
238 		 */
239 		err = tz->ops->get_trip_temp(tz, 0, &trip_temp);
240 		if (err < 0) {
241 			dev_err(&pdev->dev,
242 				"Not able to read trip_temp: %d\n",
243 				err);
244 			goto err_tz;
245 		}
246 
247 		/* set bandgap reference voltage and enable voltage regulator */
248 		val = (BCM2835_TS_TSENSCTL_CTRL_DEFAULT <<
249 		       BCM2835_TS_TSENSCTL_CTRL_SHIFT) |
250 		      BCM2835_TS_TSENSCTL_REGULEN;
251 
252 		/* use the recommended reset duration */
253 		val |= (0xFE << BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT);
254 
255 		/*  trip_adc value from info */
256 		val |= bcm2835_thermal_temp2adc(trip_temp,
257 						offset,
258 						slope)
259 			<< BCM2835_TS_TSENSCTL_THOLD_SHIFT;
260 
261 		/* write the value back to the register as 2 steps */
262 		writel(val, data->regs + BCM2835_TS_TSENSCTL);
263 		val |= BCM2835_TS_TSENSCTL_RSTB;
264 		writel(val, data->regs + BCM2835_TS_TSENSCTL);
265 	}
266 
267 	data->tz = tz;
268 
269 	platform_set_drvdata(pdev, tz);
270 
271 	/*
272 	 * Thermal_zone doesn't enable hwmon as default,
273 	 * enable it here
274 	 */
275 	tz->tzp->no_hwmon = false;
276 	err = thermal_add_hwmon_sysfs(tz);
277 	if (err)
278 		goto err_tz;
279 
280 	bcm2835_thermal_debugfs(pdev);
281 
282 	return 0;
283 err_tz:
284 	thermal_zone_of_sensor_unregister(&pdev->dev, tz);
285 err_clk:
286 	clk_disable_unprepare(data->clk);
287 
288 	return err;
289 }
290 
291 static int bcm2835_thermal_remove(struct platform_device *pdev)
292 {
293 	struct thermal_zone_device *tz = platform_get_drvdata(pdev);
294 	struct bcm2835_thermal_data *data = tz->devdata;
295 
296 	debugfs_remove_recursive(data->debugfsdir);
297 	thermal_zone_of_sensor_unregister(&pdev->dev, tz);
298 	clk_disable_unprepare(data->clk);
299 
300 	return 0;
301 }
302 
303 static struct platform_driver bcm2835_thermal_driver = {
304 	.probe = bcm2835_thermal_probe,
305 	.remove = bcm2835_thermal_remove,
306 	.driver = {
307 		.name = "bcm2835_thermal",
308 		.of_match_table = bcm2835_thermal_of_match_table,
309 	},
310 };
311 module_platform_driver(bcm2835_thermal_driver);
312 
313 MODULE_AUTHOR("Martin Sperl");
314 MODULE_DESCRIPTION("Thermal driver for bcm2835 chip");
315 MODULE_LICENSE("GPL");
316