tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
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(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
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 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
141static 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
153static 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};
165MODULE_DEVICE_TABLE(of, bcm2835_thermal_of_match_table);
166
167static 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;
283err_tz:
284 thermal_zone_of_sensor_unregister(&pdev->dev, tz);
285err_clk:
286 clk_disable_unprepare(data->clk);
287
288 return err;
289}
290
291static 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
303static 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};
311module_platform_driver(bcm2835_thermal_driver);
312
313MODULE_AUTHOR("Martin Sperl");
314MODULE_DESCRIPTION("Thermal driver for bcm2835 chip");
315MODULE_LICENSE("GPL");