1 // SPDX-License-Identifier: GPL-2.0+
3 * Driver for Broadcom BCM2835 SoC temperature sensor
5 * Copyright (C) 2016 Martin Sperl
9 #include <linux/debugfs.h>
10 #include <linux/device.h>
11 #include <linux/err.h>
13 #include <linux/kernel.h>
14 #include <linux/module.h>
16 #include <linux/of_address.h>
17 #include <linux/of_device.h>
18 #include <linux/platform_device.h>
19 #include <linux/thermal.h>
21 #include "../thermal_hwmon.h"
23 #define BCM2835_TS_TSENSCTL 0x00
24 #define BCM2835_TS_TSENSSTAT 0x04
26 #define BCM2835_TS_TSENSCTL_PRWDW BIT(0)
27 #define BCM2835_TS_TSENSCTL_RSTB BIT(1)
30 * bandgap reference voltage in 6 mV increments
31 * 000b = 1178 mV, 001b = 1184 mV, ... 111b = 1220 mV
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)
50 * time how long the block to be asserted in reset
51 * which based on a clock counter (TSENS clock assumed)
53 #define BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT 18
54 #define BCM2835_TS_TSENSCTL_RSTDELAY_BITS 8
55 #define BCM2835_TS_TSENSCTL_REGULEN BIT(26)
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)
66 struct bcm2835_thermal_data {
67 struct thermal_zone_device *tz;
70 struct dentry *debugfsdir;
73 static int bcm2835_thermal_adc2temp(u32 adc, int offset, int slope)
75 return offset + slope * adc;
78 static int bcm2835_thermal_temp2adc(int temp, int offset, int slope)
85 if (temp >= BIT(BCM2835_TS_TSENSSTAT_DATA_BITS))
86 temp = BIT(BCM2835_TS_TSENSSTAT_DATA_BITS) - 1;
91 static int bcm2835_thermal_get_temp(struct thermal_zone_device *tz, int *temp)
93 struct bcm2835_thermal_data *data = thermal_zone_device_priv(tz);
94 u32 val = readl(data->regs + BCM2835_TS_TSENSSTAT);
96 if (!(val & BCM2835_TS_TSENSSTAT_VALID))
99 val &= BCM2835_TS_TSENSSTAT_DATA_MASK;
101 *temp = bcm2835_thermal_adc2temp(
103 thermal_zone_get_offset(data->tz),
104 thermal_zone_get_slope(data->tz));
109 static const struct debugfs_reg32 bcm2835_thermal_regs[] = {
120 static void bcm2835_thermal_debugfs(struct platform_device *pdev)
122 struct bcm2835_thermal_data *data = platform_get_drvdata(pdev);
123 struct debugfs_regset32 *regset;
125 data->debugfsdir = debugfs_create_dir("bcm2835_thermal", NULL);
127 regset = devm_kzalloc(&pdev->dev, sizeof(*regset), GFP_KERNEL);
131 regset->regs = bcm2835_thermal_regs;
132 regset->nregs = ARRAY_SIZE(bcm2835_thermal_regs);
133 regset->base = data->regs;
135 debugfs_create_regset32("regset", 0444, data->debugfsdir, regset);
138 static const struct thermal_zone_device_ops bcm2835_thermal_ops = {
139 .get_temp = bcm2835_thermal_get_temp,
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
150 static const struct of_device_id bcm2835_thermal_of_match_table[] = {
152 .compatible = "brcm,bcm2835-thermal",
155 .compatible = "brcm,bcm2836-thermal",
158 .compatible = "brcm,bcm2837-thermal",
162 MODULE_DEVICE_TABLE(of, bcm2835_thermal_of_match_table);
164 static int bcm2835_thermal_probe(struct platform_device *pdev)
166 const struct of_device_id *match;
167 struct thermal_zone_device *tz;
168 struct bcm2835_thermal_data *data;
173 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
177 match = of_match_device(bcm2835_thermal_of_match_table,
182 data->regs = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
183 if (IS_ERR(data->regs)) {
184 err = PTR_ERR(data->regs);
188 data->clk = devm_clk_get(&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);
196 err = clk_prepare_enable(data->clk);
200 rate = clk_get_rate(data->clk);
201 if ((rate < 1920000) || (rate > 5000000))
203 "Clock %pCn running at %lu Hz is outside of the recommended range: 1.92 to 5MHz\n",
206 /* register of thermal sensor and get info from DT */
207 tz = devm_thermal_of_zone_register(&pdev->dev, 0, data,
208 &bcm2835_thermal_ops);
212 "Failed to register the thermal device: %d\n",
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.
223 val = readl(data->regs + BCM2835_TS_TSENSCTL);
224 if (!(val & BCM2835_TS_TSENSCTL_RSTB)) {
225 struct thermal_trip trip;
228 slope = thermal_zone_get_slope(tz);
229 offset = thermal_zone_get_offset(tz);
231 * For now we deal only with critical, otherwise
232 * would need to iterate
234 err = thermal_zone_get_trip(tz, 0, &trip);
237 "Not able to read trip_temp: %d\n",
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;
247 /* use the recommended reset duration */
248 val |= (0xFE << BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT);
250 /* trip_adc value from info */
251 val |= bcm2835_thermal_temp2adc(trip.temperature,
254 << BCM2835_TS_TSENSCTL_THOLD_SHIFT;
256 /* write the value back to the register as 2 steps */
257 writel(val, data->regs + BCM2835_TS_TSENSCTL);
258 val |= BCM2835_TS_TSENSCTL_RSTB;
259 writel(val, data->regs + BCM2835_TS_TSENSCTL);
264 platform_set_drvdata(pdev, data);
267 * Thermal_zone doesn't enable hwmon as default,
270 err = thermal_add_hwmon_sysfs(tz);
274 bcm2835_thermal_debugfs(pdev);
278 devm_thermal_of_zone_unregister(&pdev->dev, tz);
280 clk_disable_unprepare(data->clk);
285 static void bcm2835_thermal_remove(struct platform_device *pdev)
287 struct bcm2835_thermal_data *data = platform_get_drvdata(pdev);
289 debugfs_remove_recursive(data->debugfsdir);
290 clk_disable_unprepare(data->clk);
293 static struct platform_driver bcm2835_thermal_driver = {
294 .probe = bcm2835_thermal_probe,
295 .remove_new = bcm2835_thermal_remove,
297 .name = "bcm2835_thermal",
298 .of_match_table = bcm2835_thermal_of_match_table,
301 module_platform_driver(bcm2835_thermal_driver);
303 MODULE_AUTHOR("Martin Sperl");
304 MODULE_DESCRIPTION("Thermal driver for bcm2835 chip");
305 MODULE_LICENSE("GPL");