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
bcm2835_thermal_adc2temp(u32 adc,int offset,int slope)73 static int bcm2835_thermal_adc2temp(u32 adc, int offset, int slope)
74 {
75 return offset + slope * adc;
76 }
77
bcm2835_thermal_temp2adc(int temp,int offset,int slope)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
bcm2835_thermal_get_temp(struct thermal_zone_device * tz,int * temp)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
bcm2835_thermal_debugfs(struct platform_device * pdev)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
bcm2835_thermal_probe(struct platform_device * pdev)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
bcm2835_thermal_remove(struct platform_device * pdev)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