summaryrefslogtreecommitdiff
path: root/drivers/thermal/broadcom/bcm2835_thermal.c
blob: 0ecf80890c84feb857d65ee90f83fcb183ade3db (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
/*
 * Driver for Broadcom BCM2835 SoC temperature sensor
 *
 * Copyright (C) 2016 Martin Sperl
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/clk.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/thermal.h>

#define BCM2835_TS_TSENSCTL			0x00
#define BCM2835_TS_TSENSSTAT			0x04

#define BCM2835_TS_TSENSCTL_PRWDW		BIT(0)
#define BCM2835_TS_TSENSCTL_RSTB		BIT(1)

/*
 * bandgap reference voltage in 6 mV increments
 * 000b = 1178 mV, 001b = 1184 mV, ... 111b = 1220 mV
 */
#define BCM2835_TS_TSENSCTL_CTRL_BITS		3
#define BCM2835_TS_TSENSCTL_CTRL_SHIFT		2
#define BCM2835_TS_TSENSCTL_CTRL_MASK		    \
	GENMASK(BCM2835_TS_TSENSCTL_CTRL_BITS +     \
		BCM2835_TS_TSENSCTL_CTRL_SHIFT - 1, \
		BCM2835_TS_TSENSCTL_CTRL_SHIFT)
#define BCM2835_TS_TSENSCTL_CTRL_DEFAULT	1
#define BCM2835_TS_TSENSCTL_EN_INT		BIT(5)
#define BCM2835_TS_TSENSCTL_DIRECT		BIT(6)
#define BCM2835_TS_TSENSCTL_CLR_INT		BIT(7)
#define BCM2835_TS_TSENSCTL_THOLD_SHIFT		8
#define BCM2835_TS_TSENSCTL_THOLD_BITS		10
#define BCM2835_TS_TSENSCTL_THOLD_MASK		     \
	GENMASK(BCM2835_TS_TSENSCTL_THOLD_BITS +     \
		BCM2835_TS_TSENSCTL_THOLD_SHIFT - 1, \
		BCM2835_TS_TSENSCTL_THOLD_SHIFT)
/*
 * time how long the block to be asserted in reset
 * which based on a clock counter (TSENS clock assumed)
 */
#define BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT	18
#define BCM2835_TS_TSENSCTL_RSTDELAY_BITS	8
#define BCM2835_TS_TSENSCTL_REGULEN		BIT(26)

#define BCM2835_TS_TSENSSTAT_DATA_BITS		10
#define BCM2835_TS_TSENSSTAT_DATA_SHIFT		0
#define BCM2835_TS_TSENSSTAT_DATA_MASK		     \
	GENMASK(BCM2835_TS_TSENSSTAT_DATA_BITS +     \
		BCM2835_TS_TSENSSTAT_DATA_SHIFT - 1, \
		BCM2835_TS_TSENSSTAT_DATA_SHIFT)
#define BCM2835_TS_TSENSSTAT_VALID		BIT(10)
#define BCM2835_TS_TSENSSTAT_INTERRUPT		BIT(11)

struct bcm2835_thermal_data {
	struct thermal_zone_device *tz;
	void __iomem *regs;
	struct clk *clk;
	struct dentry *debugfsdir;
};

static int bcm2835_thermal_adc2temp(u32 adc, int offset, int slope)
{
	return offset + slope * adc;
}

static int bcm2835_thermal_temp2adc(int temp, int offset, int slope)
{
	temp -= offset;
	temp /= slope;

	if (temp < 0)
		temp = 0;
	if (temp >= BIT(BCM2835_TS_TSENSSTAT_DATA_BITS))
		temp = BIT(BCM2835_TS_TSENSSTAT_DATA_BITS) - 1;

	return temp;
}

static int bcm2835_thermal_get_temp(void *d, int *temp)
{
	struct bcm2835_thermal_data *data = d;
	u32 val = readl(data->regs + BCM2835_TS_TSENSSTAT);

	if (!(val & BCM2835_TS_TSENSSTAT_VALID))
		return -EIO;

	val &= BCM2835_TS_TSENSSTAT_DATA_MASK;

	*temp = bcm2835_thermal_adc2temp(
		val,
		thermal_zone_get_offset(data->tz),
		thermal_zone_get_slope(data->tz));

	return 0;
}

static const struct debugfs_reg32 bcm2835_thermal_regs[] = {
	{
		.name = "ctl",
		.offset = 0
	},
	{
		.name = "stat",
		.offset = 4
	}
};

static void bcm2835_thermal_debugfs(struct platform_device *pdev)
{
	struct thermal_zone_device *tz = platform_get_drvdata(pdev);
	struct bcm2835_thermal_data *data = tz->devdata;
	struct debugfs_regset32 *regset;

	data->debugfsdir = debugfs_create_dir("bcm2835_thermal", NULL);
	if (!data->debugfsdir)
		return;

	regset = devm_kzalloc(&pdev->dev, sizeof(*regset), GFP_KERNEL);
	if (!regset)
		return;

	regset->regs = bcm2835_thermal_regs;
	regset->nregs = ARRAY_SIZE(bcm2835_thermal_regs);
	regset->base = data->regs;

	debugfs_create_regset32("regset", 0444, data->debugfsdir, regset);
}

static struct thermal_zone_of_device_ops bcm2835_thermal_ops = {
	.get_temp = bcm2835_thermal_get_temp,
};

/*
 * Note: as per Raspberry Foundation FAQ
 * (https://www.raspberrypi.org/help/faqs/#performanceOperatingTemperature)
 * the recommended temperature range for the SoC -40C to +85C
 * so the trip limit is set to 80C.
 * this applies to all the BCM283X SoC
 */

static const struct of_device_id bcm2835_thermal_of_match_table[] = {
	{
		.compatible = "brcm,bcm2835-thermal",
	},
	{
		.compatible = "brcm,bcm2836-thermal",
	},
	{
		.compatible = "brcm,bcm2837-thermal",
	},
	{},
};
MODULE_DEVICE_TABLE(of, bcm2835_thermal_of_match_table);

static int bcm2835_thermal_probe(struct platform_device *pdev)
{
	const struct of_device_id *match;
	struct thermal_zone_device *tz;
	struct bcm2835_thermal_data *data;
	struct resource *res;
	int err = 0;
	u32 val;
	unsigned long rate;

	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	match = of_match_device(bcm2835_thermal_of_match_table,
				&pdev->dev);
	if (!match)
		return -EINVAL;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	data->regs = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(data->regs)) {
		err = PTR_ERR(data->regs);
		dev_err(&pdev->dev, "Could not get registers: %d\n", err);
		return err;
	}

	data->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(data->clk)) {
		err = PTR_ERR(data->clk);
		if (err != -EPROBE_DEFER)
			dev_err(&pdev->dev, "Could not get clk: %d\n", err);
		return err;
	}

	err = clk_prepare_enable(data->clk);
	if (err)
		return err;

	rate = clk_get_rate(data->clk);
	if ((rate < 1920000) || (rate > 5000000))
		dev_warn(&pdev->dev,
			 "Clock %pCn running at %pCr Hz is outside of the recommended range: 1.92 to 5MHz\n",
			 data->clk, data->clk);

	/* register of thermal sensor and get info from DT */
	tz = thermal_zone_of_sensor_register(&pdev->dev, 0, data,
					     &bcm2835_thermal_ops);
	if (IS_ERR(tz)) {
		err = PTR_ERR(tz);
		dev_err(&pdev->dev,
			"Failed to register the thermal device: %d\n",
			err);
		goto err_clk;
	}

	/*
	 * right now the FW does set up the HW-block, so we are not
	 * touching the configuration registers.
	 * But if the HW is not enabled, then set it up
	 * using "sane" values used by the firmware right now.
	 */
	val = readl(data->regs + BCM2835_TS_TSENSCTL);
	if (!(val & BCM2835_TS_TSENSCTL_RSTB)) {
		int trip_temp, offset, slope;

		slope = thermal_zone_get_slope(tz);
		offset = thermal_zone_get_offset(tz);
		/*
		 * For now we deal only with critical, otherwise
		 * would need to iterate
		 */
		err = tz->ops->get_trip_temp(tz, 0, &trip_temp);
		if (err < 0) {
			err = PTR_ERR(tz);
			dev_err(&pdev->dev,
				"Not able to read trip_temp: %d\n",
				err);
			goto err_tz;
		}

		/* set bandgap reference voltage and enable voltage regulator */
		val = (BCM2835_TS_TSENSCTL_CTRL_DEFAULT <<
		       BCM2835_TS_TSENSCTL_CTRL_SHIFT) |
		      BCM2835_TS_TSENSCTL_REGULEN;

		/* use the recommended reset duration */
		val |= (0xFE << BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT);

		/*  trip_adc value from info */
		val |= bcm2835_thermal_temp2adc(trip_temp,
						offset,
						slope)
			<< BCM2835_TS_TSENSCTL_THOLD_SHIFT;

		/* write the value back to the register as 2 steps */
		writel(val, data->regs + BCM2835_TS_TSENSCTL);
		val |= BCM2835_TS_TSENSCTL_RSTB;
		writel(val, data->regs + BCM2835_TS_TSENSCTL);
	}

	data->tz = tz;

	platform_set_drvdata(pdev, tz);

	bcm2835_thermal_debugfs(pdev);

	return 0;
err_tz:
	thermal_zone_of_sensor_unregister(&pdev->dev, tz);
err_clk:
	clk_disable_unprepare(data->clk);

	return err;
}

static int bcm2835_thermal_remove(struct platform_device *pdev)
{
	struct thermal_zone_device *tz = platform_get_drvdata(pdev);
	struct bcm2835_thermal_data *data = tz->devdata;

	debugfs_remove_recursive(data->debugfsdir);
	thermal_zone_of_sensor_unregister(&pdev->dev, tz);
	clk_disable_unprepare(data->clk);

	return 0;
}

static struct platform_driver bcm2835_thermal_driver = {
	.probe = bcm2835_thermal_probe,
	.remove = bcm2835_thermal_remove,
	.driver = {
		.name = "bcm2835_thermal",
		.of_match_table = bcm2835_thermal_of_match_table,
	},
};
module_platform_driver(bcm2835_thermal_driver);

MODULE_AUTHOR("Martin Sperl");
MODULE_DESCRIPTION("Thermal driver for bcm2835 chip");
MODULE_LICENSE("GPL");