1 /*
2  *  R-Car Gen3 THS thermal sensor driver
3  *  Based on rcar_thermal.c and work from Hien Dang and Khiem Nguyen.
4  *
5  * Copyright (C) 2016 Renesas Electronics Corporation.
6  * Copyright (C) 2016 Sang Engineering
7  *
8  *  This program is free software; you can redistribute it and/or modify
9  *  it under the terms of the GNU General Public License as published by
10  *  the Free Software Foundation; version 2 of the License.
11  *
12  *  This program is distributed in the hope that it will be useful, but
13  *  WITHOUT ANY WARRANTY; without even the implied warranty of
14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15  *  General Public License for more details.
16  *
17  */
18 #include <linux/delay.h>
19 #include <linux/err.h>
20 #include <linux/interrupt.h>
21 #include <linux/io.h>
22 #include <linux/module.h>
23 #include <linux/mutex.h>
24 #include <linux/of_device.h>
25 #include <linux/platform_device.h>
26 #include <linux/pm_runtime.h>
27 #include <linux/thermal.h>
28 
29 /* Register offsets */
30 #define REG_GEN3_IRQSTR		0x04
31 #define REG_GEN3_IRQMSK		0x08
32 #define REG_GEN3_IRQCTL		0x0C
33 #define REG_GEN3_IRQEN		0x10
34 #define REG_GEN3_IRQTEMP1	0x14
35 #define REG_GEN3_IRQTEMP2	0x18
36 #define REG_GEN3_IRQTEMP3	0x1C
37 #define REG_GEN3_CTSR		0x20
38 #define REG_GEN3_THCTR		0x20
39 #define REG_GEN3_TEMP		0x28
40 #define REG_GEN3_THCODE1	0x50
41 #define REG_GEN3_THCODE2	0x54
42 #define REG_GEN3_THCODE3	0x58
43 
44 /* CTSR bits */
45 #define CTSR_PONM	BIT(8)
46 #define CTSR_AOUT	BIT(7)
47 #define CTSR_THBGR	BIT(5)
48 #define CTSR_VMEN	BIT(4)
49 #define CTSR_VMST	BIT(1)
50 #define CTSR_THSST	BIT(0)
51 
52 /* THCTR bits */
53 #define THCTR_PONM	BIT(6)
54 #define THCTR_THSST	BIT(0)
55 
56 #define CTEMP_MASK	0xFFF
57 
58 #define MCELSIUS(temp)	((temp) * 1000)
59 #define GEN3_FUSE_MASK	0xFFF
60 
61 #define TSC_MAX_NUM	3
62 
63 /* Structure for thermal temperature calculation */
64 struct equation_coefs {
65 	int a1;
66 	int b1;
67 	int a2;
68 	int b2;
69 };
70 
71 struct rcar_gen3_thermal_tsc {
72 	void __iomem *base;
73 	struct thermal_zone_device *zone;
74 	struct equation_coefs coef;
75 	struct mutex lock;
76 };
77 
78 struct rcar_gen3_thermal_priv {
79 	struct rcar_gen3_thermal_tsc *tscs[TSC_MAX_NUM];
80 };
81 
82 struct rcar_gen3_thermal_data {
83 	void (*thermal_init)(struct rcar_gen3_thermal_tsc *tsc);
84 };
85 
86 static inline u32 rcar_gen3_thermal_read(struct rcar_gen3_thermal_tsc *tsc,
87 					 u32 reg)
88 {
89 	return ioread32(tsc->base + reg);
90 }
91 
92 static inline void rcar_gen3_thermal_write(struct rcar_gen3_thermal_tsc *tsc,
93 					   u32 reg, u32 data)
94 {
95 	iowrite32(data, tsc->base + reg);
96 }
97 
98 /*
99  * Linear approximation for temperature
100  *
101  * [reg] = [temp] * a + b => [temp] = ([reg] - b) / a
102  *
103  * The constants a and b are calculated using two triplets of int values PTAT
104  * and THCODE. PTAT and THCODE can either be read from hardware or use hard
105  * coded values from driver. The formula to calculate a and b are taken from
106  * BSP and sparsely documented and understood.
107  *
108  * Examining the linear formula and the formula used to calculate constants a
109  * and b while knowing that the span for PTAT and THCODE values are between
110  * 0x000 and 0xfff the largest integer possible is 0xfff * 0xfff == 0xffe001.
111  * Integer also needs to be signed so that leaves 7 bits for binary
112  * fixed point scaling.
113  */
114 
115 #define FIXPT_SHIFT 7
116 #define FIXPT_INT(_x) ((_x) << FIXPT_SHIFT)
117 #define FIXPT_DIV(_a, _b) DIV_ROUND_CLOSEST(((_a) << FIXPT_SHIFT), (_b))
118 #define FIXPT_TO_MCELSIUS(_x) ((_x) * 1000 >> FIXPT_SHIFT)
119 
120 #define RCAR3_THERMAL_GRAN 500 /* mili Celsius */
121 
122 /* no idea where these constants come from */
123 #define TJ_1 96
124 #define TJ_3 -41
125 
126 static void rcar_gen3_thermal_calc_coefs(struct equation_coefs *coef,
127 					 int *ptat, int *thcode)
128 {
129 	int tj_2;
130 
131 	/* TODO: Find documentation and document constant calculation formula */
132 
133 	/*
134 	 * Division is not scaled in BSP and if scaled it might overflow
135 	 * the dividend (4095 * 4095 << 14 > INT_MAX) so keep it unscaled
136 	 */
137 	tj_2 = (FIXPT_INT((ptat[1] - ptat[2]) * 137)
138 		/ (ptat[0] - ptat[2])) - FIXPT_INT(41);
139 
140 	coef->a1 = FIXPT_DIV(FIXPT_INT(thcode[1] - thcode[2]),
141 			     tj_2 - FIXPT_INT(TJ_3));
142 	coef->b1 = FIXPT_INT(thcode[2]) - coef->a1 * TJ_3;
143 
144 	coef->a2 = FIXPT_DIV(FIXPT_INT(thcode[1] - thcode[0]),
145 			     tj_2 - FIXPT_INT(TJ_1));
146 	coef->b2 = FIXPT_INT(thcode[0]) - coef->a2 * TJ_1;
147 }
148 
149 static int rcar_gen3_thermal_round(int temp)
150 {
151 	int result, round_offs;
152 
153 	round_offs = temp >= 0 ? RCAR3_THERMAL_GRAN / 2 :
154 		-RCAR3_THERMAL_GRAN / 2;
155 	result = (temp + round_offs) / RCAR3_THERMAL_GRAN;
156 	return result * RCAR3_THERMAL_GRAN;
157 }
158 
159 static int rcar_gen3_thermal_get_temp(void *devdata, int *temp)
160 {
161 	struct rcar_gen3_thermal_tsc *tsc = devdata;
162 	int mcelsius, val1, val2;
163 	u32 reg;
164 
165 	/* Read register and convert to mili Celsius */
166 	mutex_lock(&tsc->lock);
167 
168 	reg = rcar_gen3_thermal_read(tsc, REG_GEN3_TEMP) & CTEMP_MASK;
169 
170 	val1 = FIXPT_DIV(FIXPT_INT(reg) - tsc->coef.b1, tsc->coef.a1);
171 	val2 = FIXPT_DIV(FIXPT_INT(reg) - tsc->coef.b2, tsc->coef.a2);
172 	mcelsius = FIXPT_TO_MCELSIUS((val1 + val2) / 2);
173 
174 	mutex_unlock(&tsc->lock);
175 
176 	/* Make sure we are inside specifications */
177 	if ((mcelsius < MCELSIUS(-40)) || (mcelsius > MCELSIUS(125)))
178 		return -EIO;
179 
180 	/* Round value to device granularity setting */
181 	*temp = rcar_gen3_thermal_round(mcelsius);
182 
183 	return 0;
184 }
185 
186 static struct thermal_zone_of_device_ops rcar_gen3_tz_of_ops = {
187 	.get_temp	= rcar_gen3_thermal_get_temp,
188 };
189 
190 static void r8a7795_thermal_init(struct rcar_gen3_thermal_tsc *tsc)
191 {
192 	rcar_gen3_thermal_write(tsc, REG_GEN3_CTSR,  CTSR_THBGR);
193 	rcar_gen3_thermal_write(tsc, REG_GEN3_CTSR,  0x0);
194 
195 	usleep_range(1000, 2000);
196 
197 	rcar_gen3_thermal_write(tsc, REG_GEN3_CTSR, CTSR_PONM);
198 	rcar_gen3_thermal_write(tsc, REG_GEN3_IRQCTL, 0x3F);
199 	rcar_gen3_thermal_write(tsc, REG_GEN3_CTSR,
200 				CTSR_PONM | CTSR_AOUT | CTSR_THBGR | CTSR_VMEN);
201 
202 	usleep_range(100, 200);
203 
204 	rcar_gen3_thermal_write(tsc, REG_GEN3_CTSR,
205 				CTSR_PONM | CTSR_AOUT | CTSR_THBGR | CTSR_VMEN |
206 				CTSR_VMST | CTSR_THSST);
207 
208 	usleep_range(1000, 2000);
209 }
210 
211 static void r8a7796_thermal_init(struct rcar_gen3_thermal_tsc *tsc)
212 {
213 	u32 reg_val;
214 
215 	reg_val = rcar_gen3_thermal_read(tsc, REG_GEN3_THCTR);
216 	reg_val &= ~THCTR_PONM;
217 	rcar_gen3_thermal_write(tsc, REG_GEN3_THCTR, reg_val);
218 
219 	usleep_range(1000, 2000);
220 
221 	rcar_gen3_thermal_write(tsc, REG_GEN3_IRQCTL, 0x3F);
222 	reg_val = rcar_gen3_thermal_read(tsc, REG_GEN3_THCTR);
223 	reg_val |= THCTR_THSST;
224 	rcar_gen3_thermal_write(tsc, REG_GEN3_THCTR, reg_val);
225 }
226 
227 static const struct rcar_gen3_thermal_data r8a7795_data = {
228 	.thermal_init = r8a7795_thermal_init,
229 };
230 
231 static const struct rcar_gen3_thermal_data r8a7796_data = {
232 	.thermal_init = r8a7796_thermal_init,
233 };
234 
235 static const struct of_device_id rcar_gen3_thermal_dt_ids[] = {
236 	{ .compatible = "renesas,r8a7795-thermal", .data = &r8a7795_data},
237 	{ .compatible = "renesas,r8a7796-thermal", .data = &r8a7796_data},
238 	{},
239 };
240 MODULE_DEVICE_TABLE(of, rcar_gen3_thermal_dt_ids);
241 
242 static int rcar_gen3_thermal_remove(struct platform_device *pdev)
243 {
244 	struct device *dev = &pdev->dev;
245 
246 	pm_runtime_put(dev);
247 	pm_runtime_disable(dev);
248 
249 	return 0;
250 }
251 
252 static int rcar_gen3_thermal_probe(struct platform_device *pdev)
253 {
254 	struct rcar_gen3_thermal_priv *priv;
255 	struct device *dev = &pdev->dev;
256 	struct resource *res;
257 	struct thermal_zone_device *zone;
258 	int ret, i;
259 	const struct rcar_gen3_thermal_data *match_data =
260 		of_device_get_match_data(dev);
261 
262 	/* default values if FUSEs are missing */
263 	/* TODO: Read values from hardware on supported platforms */
264 	int ptat[3] = { 2351, 1509, 435 };
265 	int thcode[TSC_MAX_NUM][3] = {
266 		{ 3248, 2800, 2221 },
267 		{ 3245, 2795, 2216 },
268 		{ 3250, 2805, 2237 },
269 	};
270 
271 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
272 	if (!priv)
273 		return -ENOMEM;
274 
275 	platform_set_drvdata(pdev, priv);
276 
277 	pm_runtime_enable(dev);
278 	pm_runtime_get_sync(dev);
279 
280 	for (i = 0; i < TSC_MAX_NUM; i++) {
281 		struct rcar_gen3_thermal_tsc *tsc;
282 
283 		tsc = devm_kzalloc(dev, sizeof(*tsc), GFP_KERNEL);
284 		if (!tsc) {
285 			ret = -ENOMEM;
286 			goto error_unregister;
287 		}
288 
289 		res = platform_get_resource(pdev, IORESOURCE_MEM, i);
290 		if (!res)
291 			break;
292 
293 		tsc->base = devm_ioremap_resource(dev, res);
294 		if (IS_ERR(tsc->base)) {
295 			ret = PTR_ERR(tsc->base);
296 			goto error_unregister;
297 		}
298 
299 		priv->tscs[i] = tsc;
300 		mutex_init(&tsc->lock);
301 
302 		match_data->thermal_init(tsc);
303 		rcar_gen3_thermal_calc_coefs(&tsc->coef, ptat, thcode[i]);
304 
305 		zone = devm_thermal_zone_of_sensor_register(dev, i, tsc,
306 							    &rcar_gen3_tz_of_ops);
307 		if (IS_ERR(zone)) {
308 			dev_err(dev, "Can't register thermal zone\n");
309 			ret = PTR_ERR(zone);
310 			goto error_unregister;
311 		}
312 		tsc->zone = zone;
313 	}
314 
315 	return 0;
316 
317 error_unregister:
318 	rcar_gen3_thermal_remove(pdev);
319 
320 	return ret;
321 }
322 
323 static struct platform_driver rcar_gen3_thermal_driver = {
324 	.driver	= {
325 		.name	= "rcar_gen3_thermal",
326 		.of_match_table = rcar_gen3_thermal_dt_ids,
327 	},
328 	.probe		= rcar_gen3_thermal_probe,
329 	.remove		= rcar_gen3_thermal_remove,
330 };
331 module_platform_driver(rcar_gen3_thermal_driver);
332 
333 MODULE_LICENSE("GPL v2");
334 MODULE_DESCRIPTION("R-Car Gen3 THS thermal sensor driver");
335 MODULE_AUTHOR("Wolfram Sang <wsa+renesas@sang-engineering.com>");
336