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
66struct bcm2835_thermal_data {
67 struct thermal_zone_device *tz;
68 void __iomem *regs;
69 struct clk *clk;
70 struct dentry *debugfsdir;
71};
72
73static int bcm2835_thermal_adc2temp(u32 adc, int offset, int slope)
74{
75 return offset + slope * adc;
76}
77
78static 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
91static int bcm2835_thermal_get_temp(struct thermal_zone_device *tz, int *temp)
92{
93 struct bcm2835_thermal_data *data = thermal_zone_device_priv(tzd: tz);
94 u32 val = readl(addr: 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 adc: val,
103 offset: thermal_zone_get_offset(tz: data->tz),
104 slope: thermal_zone_get_slope(tz: data->tz));
105
106 return 0;
107}
108
109static 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
120static 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(name: "bcm2835_thermal", NULL);
126
127 regset = devm_kzalloc(dev: &pdev->dev, size: 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(name: "regset", mode: 0444, parent: data->debugfsdir, regset);
136}
137
138static 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
150static 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};
162MODULE_DEVICE_TABLE(of, bcm2835_thermal_of_match_table);
163
164static 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(dev: &pdev->dev, size: sizeof(*data), GFP_KERNEL);
174 if (!data)
175 return -ENOMEM;
176
177 match = of_match_device(matches: bcm2835_thermal_of_match_table,
178 dev: &pdev->dev);
179 if (!match)
180 return -EINVAL;
181
182 data->regs = devm_platform_get_and_ioremap_resource(pdev, index: 0, NULL);
183 if (IS_ERR(ptr: data->regs)) {
184 err = PTR_ERR(ptr: data->regs);
185 return err;
186 }
187
188 data->clk = devm_clk_get(dev: &pdev->dev, NULL);
189 if (IS_ERR(ptr: data->clk)) {
190 err = PTR_ERR(ptr: 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 err = clk_prepare_enable(clk: data->clk);
197 if (err)
198 return err;
199
200 rate = clk_get_rate(clk: data->clk);
201 if ((rate < 1920000) || (rate > 5000000))
202 dev_warn(&pdev->dev,
203 "Clock %pCn running at %lu Hz is outside of the recommended range: 1.92 to 5MHz\n",
204 data->clk, rate);
205
206 /* register of thermal sensor and get info from DT */
207 tz = devm_thermal_of_zone_register(dev: &pdev->dev, id: 0, data,
208 ops: &bcm2835_thermal_ops);
209 if (IS_ERR(ptr: tz)) {
210 err = PTR_ERR(ptr: tz);
211 dev_err(&pdev->dev,
212 "Failed to register the thermal device: %d\n",
213 err);
214 goto err_clk;
215 }
216
217 /*
218 * right now the FW does set up the HW-block, so we are not
219 * touching the configuration registers.
220 * But if the HW is not enabled, then set it up
221 * using "sane" values used by the firmware right now.
222 */
223 val = readl(addr: data->regs + BCM2835_TS_TSENSCTL);
224 if (!(val & BCM2835_TS_TSENSCTL_RSTB)) {
225 struct thermal_trip trip;
226 int offset, slope;
227
228 slope = thermal_zone_get_slope(tz);
229 offset = thermal_zone_get_offset(tz);
230 /*
231 * For now we deal only with critical, otherwise
232 * would need to iterate
233 */
234 err = thermal_zone_get_trip(tz, trip_id: 0, trip: &trip);
235 if (err < 0) {
236 dev_err(&pdev->dev,
237 "Not able to read trip_temp: %d\n",
238 err);
239 goto err_tz;
240 }
241
242 /* set bandgap reference voltage and enable voltage regulator */
243 val = (BCM2835_TS_TSENSCTL_CTRL_DEFAULT <<
244 BCM2835_TS_TSENSCTL_CTRL_SHIFT) |
245 BCM2835_TS_TSENSCTL_REGULEN;
246
247 /* use the recommended reset duration */
248 val |= (0xFE << BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT);
249
250 /* trip_adc value from info */
251 val |= bcm2835_thermal_temp2adc(temp: trip.temperature,
252 offset,
253 slope)
254 << BCM2835_TS_TSENSCTL_THOLD_SHIFT;
255
256 /* write the value back to the register as 2 steps */
257 writel(val, addr: data->regs + BCM2835_TS_TSENSCTL);
258 val |= BCM2835_TS_TSENSCTL_RSTB;
259 writel(val, addr: data->regs + BCM2835_TS_TSENSCTL);
260 }
261
262 data->tz = tz;
263
264 platform_set_drvdata(pdev, data);
265
266 /*
267 * Thermal_zone doesn't enable hwmon as default,
268 * enable it here
269 */
270 err = thermal_add_hwmon_sysfs(tz);
271 if (err)
272 goto err_tz;
273
274 bcm2835_thermal_debugfs(pdev);
275
276 return 0;
277err_tz:
278 devm_thermal_of_zone_unregister(dev: &pdev->dev, tz);
279err_clk:
280 clk_disable_unprepare(clk: data->clk);
281
282 return err;
283}
284
285static void bcm2835_thermal_remove(struct platform_device *pdev)
286{
287 struct bcm2835_thermal_data *data = platform_get_drvdata(pdev);
288
289 debugfs_remove_recursive(dentry: data->debugfsdir);
290 clk_disable_unprepare(clk: data->clk);
291}
292
293static struct platform_driver bcm2835_thermal_driver = {
294 .probe = bcm2835_thermal_probe,
295 .remove_new = bcm2835_thermal_remove,
296 .driver = {
297 .name = "bcm2835_thermal",
298 .of_match_table = bcm2835_thermal_of_match_table,
299 },
300};
301module_platform_driver(bcm2835_thermal_driver);
302
303MODULE_AUTHOR("Martin Sperl");
304MODULE_DESCRIPTION("Thermal driver for bcm2835 chip");
305MODULE_LICENSE("GPL");
306

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source code of linux/drivers/thermal/broadcom/bcm2835_thermal.c