1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (c) 2019 Nuvoton Technology corporation.
3
4 #include <linux/clk.h>
5 #include <linux/device.h>
6 #include <linux/mfd/syscon.h>
7 #include <linux/io.h>
8 #include <linux/iio/iio.h>
9 #include <linux/interrupt.h>
10 #include <linux/kernel.h>
11 #include <linux/mod_devicetable.h>
12 #include <linux/module.h>
13 #include <linux/platform_device.h>
14 #include <linux/property.h>
15 #include <linux/regmap.h>
16 #include <linux/regulator/consumer.h>
17 #include <linux/spinlock.h>
18 #include <linux/uaccess.h>
19 #include <linux/reset.h>
20
21 struct npcm_adc_info {
22 u32 data_mask;
23 u32 internal_vref;
24 u32 res_bits;
25 };
26
27 struct npcm_adc {
28 bool int_status;
29 u32 adc_sample_hz;
30 struct device *dev;
31 void __iomem *regs;
32 struct clk *adc_clk;
33 wait_queue_head_t wq;
34 struct regulator *vref;
35 struct reset_control *reset;
36 /*
37 * Lock to protect the device state during a potential concurrent
38 * read access from userspace. Reading a raw value requires a sequence
39 * of register writes, then a wait for a event and finally a register
40 * read, during which userspace could issue another read request.
41 * This lock protects a read access from ocurring before another one
42 * has finished.
43 */
44 struct mutex lock;
45 const struct npcm_adc_info *data;
46 };
47
48 /* ADC registers */
49 #define NPCM_ADCCON 0x00
50 #define NPCM_ADCDATA 0x04
51
52 /* ADCCON Register Bits */
53 #define NPCM_ADCCON_ADC_INT_EN BIT(21)
54 #define NPCM_ADCCON_REFSEL BIT(19)
55 #define NPCM_ADCCON_ADC_INT_ST BIT(18)
56 #define NPCM_ADCCON_ADC_EN BIT(17)
57 #define NPCM_ADCCON_ADC_RST BIT(16)
58 #define NPCM_ADCCON_ADC_CONV BIT(13)
59
60 #define NPCM_ADCCON_CH_MASK GENMASK(27, 24)
61 #define NPCM_ADCCON_CH(x) ((x) << 24)
62 #define NPCM_ADCCON_DIV_SHIFT 1
63 #define NPCM_ADCCON_DIV_MASK GENMASK(8, 1)
64
65 #define NPCM_ADC_ENABLE (NPCM_ADCCON_ADC_EN | NPCM_ADCCON_ADC_INT_EN)
66
67 /* ADC General Definition */
68 static const struct npcm_adc_info npxm7xx_adc_info = {
69 .data_mask = GENMASK(9, 0),
70 .internal_vref = 2048,
71 .res_bits = 10,
72 };
73
74 static const struct npcm_adc_info npxm8xx_adc_info = {
75 .data_mask = GENMASK(11, 0),
76 .internal_vref = 1229,
77 .res_bits = 12,
78 };
79
80 #define NPCM_ADC_CHAN(ch) { \
81 .type = IIO_VOLTAGE, \
82 .indexed = 1, \
83 .channel = ch, \
84 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
85 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \
86 BIT(IIO_CHAN_INFO_SAMP_FREQ), \
87 }
88
89 static const struct iio_chan_spec npcm_adc_iio_channels[] = {
90 NPCM_ADC_CHAN(0),
91 NPCM_ADC_CHAN(1),
92 NPCM_ADC_CHAN(2),
93 NPCM_ADC_CHAN(3),
94 NPCM_ADC_CHAN(4),
95 NPCM_ADC_CHAN(5),
96 NPCM_ADC_CHAN(6),
97 NPCM_ADC_CHAN(7),
98 };
99
npcm_adc_isr(int irq,void * data)100 static irqreturn_t npcm_adc_isr(int irq, void *data)
101 {
102 u32 regtemp;
103 struct iio_dev *indio_dev = data;
104 struct npcm_adc *info = iio_priv(indio_dev);
105
106 regtemp = ioread32(info->regs + NPCM_ADCCON);
107 if (regtemp & NPCM_ADCCON_ADC_INT_ST) {
108 iowrite32(regtemp, info->regs + NPCM_ADCCON);
109 wake_up_interruptible(&info->wq);
110 info->int_status = true;
111 }
112
113 return IRQ_HANDLED;
114 }
115
npcm_adc_read(struct npcm_adc * info,int * val,u8 channel)116 static int npcm_adc_read(struct npcm_adc *info, int *val, u8 channel)
117 {
118 int ret;
119 u32 regtemp;
120
121 /* Select ADC channel */
122 regtemp = ioread32(info->regs + NPCM_ADCCON);
123 regtemp &= ~NPCM_ADCCON_CH_MASK;
124 info->int_status = false;
125 iowrite32(regtemp | NPCM_ADCCON_CH(channel) |
126 NPCM_ADCCON_ADC_CONV, info->regs + NPCM_ADCCON);
127
128 ret = wait_event_interruptible_timeout(info->wq, info->int_status,
129 msecs_to_jiffies(10));
130 if (ret == 0) {
131 regtemp = ioread32(info->regs + NPCM_ADCCON);
132 if (regtemp & NPCM_ADCCON_ADC_CONV) {
133 /* if conversion failed - reset ADC module */
134 reset_control_assert(info->reset);
135 msleep(100);
136 reset_control_deassert(info->reset);
137 msleep(100);
138
139 /* Enable ADC and start conversion module */
140 iowrite32(NPCM_ADC_ENABLE | NPCM_ADCCON_ADC_CONV,
141 info->regs + NPCM_ADCCON);
142 dev_err(info->dev, "RESET ADC Complete\n");
143 }
144 return -ETIMEDOUT;
145 }
146 if (ret < 0)
147 return ret;
148
149 *val = ioread32(info->regs + NPCM_ADCDATA);
150 *val &= info->data->data_mask;
151
152 return 0;
153 }
154
npcm_adc_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)155 static int npcm_adc_read_raw(struct iio_dev *indio_dev,
156 struct iio_chan_spec const *chan, int *val,
157 int *val2, long mask)
158 {
159 int ret;
160 int vref_uv;
161 struct npcm_adc *info = iio_priv(indio_dev);
162
163 switch (mask) {
164 case IIO_CHAN_INFO_RAW:
165 mutex_lock(&info->lock);
166 ret = npcm_adc_read(info, val, chan->channel);
167 mutex_unlock(&info->lock);
168 if (ret) {
169 dev_err(info->dev, "NPCM ADC read failed\n");
170 return ret;
171 }
172 return IIO_VAL_INT;
173 case IIO_CHAN_INFO_SCALE:
174 if (!IS_ERR(info->vref)) {
175 vref_uv = regulator_get_voltage(info->vref);
176 *val = vref_uv / 1000;
177 } else {
178 *val = info->data->internal_vref;
179 }
180 *val2 = info->data->res_bits;
181 return IIO_VAL_FRACTIONAL_LOG2;
182 case IIO_CHAN_INFO_SAMP_FREQ:
183 *val = info->adc_sample_hz;
184 return IIO_VAL_INT;
185 default:
186 return -EINVAL;
187 }
188
189 return 0;
190 }
191
192 static const struct iio_info npcm_adc_iio_info = {
193 .read_raw = &npcm_adc_read_raw,
194 };
195
196 static const struct of_device_id npcm_adc_match[] = {
197 { .compatible = "nuvoton,npcm750-adc", .data = &npxm7xx_adc_info},
198 { .compatible = "nuvoton,npcm845-adc", .data = &npxm8xx_adc_info},
199 { /* sentinel */ }
200 };
201 MODULE_DEVICE_TABLE(of, npcm_adc_match);
202
npcm_adc_probe(struct platform_device * pdev)203 static int npcm_adc_probe(struct platform_device *pdev)
204 {
205 int ret;
206 int irq;
207 u32 div;
208 u32 reg_con;
209 struct npcm_adc *info;
210 struct iio_dev *indio_dev;
211 struct device *dev = &pdev->dev;
212
213 indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*info));
214 if (!indio_dev)
215 return -ENOMEM;
216 info = iio_priv(indio_dev);
217
218 info->data = device_get_match_data(dev);
219 if (!info->data)
220 return -EINVAL;
221
222 mutex_init(&info->lock);
223
224 info->dev = &pdev->dev;
225
226 info->regs = devm_platform_ioremap_resource(pdev, 0);
227 if (IS_ERR(info->regs))
228 return PTR_ERR(info->regs);
229
230 info->reset = devm_reset_control_get(&pdev->dev, NULL);
231 if (IS_ERR(info->reset))
232 return PTR_ERR(info->reset);
233
234 info->adc_clk = devm_clk_get(&pdev->dev, NULL);
235 if (IS_ERR(info->adc_clk)) {
236 dev_warn(&pdev->dev, "ADC clock failed: can't read clk\n");
237 return PTR_ERR(info->adc_clk);
238 }
239
240 /* calculate ADC clock sample rate */
241 reg_con = ioread32(info->regs + NPCM_ADCCON);
242 div = reg_con & NPCM_ADCCON_DIV_MASK;
243 div = div >> NPCM_ADCCON_DIV_SHIFT;
244 info->adc_sample_hz = clk_get_rate(info->adc_clk) / ((div + 1) * 2);
245
246 irq = platform_get_irq(pdev, 0);
247 if (irq < 0) {
248 ret = irq;
249 goto err_disable_clk;
250 }
251
252 ret = devm_request_irq(&pdev->dev, irq, npcm_adc_isr, 0,
253 "NPCM_ADC", indio_dev);
254 if (ret < 0) {
255 dev_err(dev, "failed requesting interrupt\n");
256 goto err_disable_clk;
257 }
258
259 reg_con = ioread32(info->regs + NPCM_ADCCON);
260 info->vref = devm_regulator_get_optional(&pdev->dev, "vref");
261 if (!IS_ERR(info->vref)) {
262 ret = regulator_enable(info->vref);
263 if (ret) {
264 dev_err(&pdev->dev, "Can't enable ADC reference voltage\n");
265 goto err_disable_clk;
266 }
267
268 iowrite32(reg_con & ~NPCM_ADCCON_REFSEL,
269 info->regs + NPCM_ADCCON);
270 } else {
271 /*
272 * Any error which is not ENODEV indicates the regulator
273 * has been specified and so is a failure case.
274 */
275 if (PTR_ERR(info->vref) != -ENODEV) {
276 ret = PTR_ERR(info->vref);
277 goto err_disable_clk;
278 }
279
280 /* Use internal reference */
281 iowrite32(reg_con | NPCM_ADCCON_REFSEL,
282 info->regs + NPCM_ADCCON);
283 }
284
285 init_waitqueue_head(&info->wq);
286
287 reg_con = ioread32(info->regs + NPCM_ADCCON);
288 reg_con |= NPCM_ADC_ENABLE;
289
290 /* Enable the ADC Module */
291 iowrite32(reg_con, info->regs + NPCM_ADCCON);
292
293 /* Start ADC conversion */
294 iowrite32(reg_con | NPCM_ADCCON_ADC_CONV, info->regs + NPCM_ADCCON);
295
296 platform_set_drvdata(pdev, indio_dev);
297 indio_dev->name = dev_name(&pdev->dev);
298 indio_dev->info = &npcm_adc_iio_info;
299 indio_dev->modes = INDIO_DIRECT_MODE;
300 indio_dev->channels = npcm_adc_iio_channels;
301 indio_dev->num_channels = ARRAY_SIZE(npcm_adc_iio_channels);
302
303 ret = iio_device_register(indio_dev);
304 if (ret) {
305 dev_err(&pdev->dev, "Couldn't register the device.\n");
306 goto err_iio_register;
307 }
308
309 pr_info("NPCM ADC driver probed\n");
310
311 return 0;
312
313 err_iio_register:
314 iowrite32(reg_con & ~NPCM_ADCCON_ADC_EN, info->regs + NPCM_ADCCON);
315 if (!IS_ERR(info->vref))
316 regulator_disable(info->vref);
317 err_disable_clk:
318 clk_disable_unprepare(info->adc_clk);
319
320 return ret;
321 }
322
npcm_adc_remove(struct platform_device * pdev)323 static int npcm_adc_remove(struct platform_device *pdev)
324 {
325 struct iio_dev *indio_dev = platform_get_drvdata(pdev);
326 struct npcm_adc *info = iio_priv(indio_dev);
327 u32 regtemp;
328
329 iio_device_unregister(indio_dev);
330
331 regtemp = ioread32(info->regs + NPCM_ADCCON);
332 iowrite32(regtemp & ~NPCM_ADCCON_ADC_EN, info->regs + NPCM_ADCCON);
333 if (!IS_ERR(info->vref))
334 regulator_disable(info->vref);
335 clk_disable_unprepare(info->adc_clk);
336
337 return 0;
338 }
339
340 static struct platform_driver npcm_adc_driver = {
341 .probe = npcm_adc_probe,
342 .remove = npcm_adc_remove,
343 .driver = {
344 .name = "npcm_adc",
345 .of_match_table = npcm_adc_match,
346 },
347 };
348
349 module_platform_driver(npcm_adc_driver);
350
351 MODULE_DESCRIPTION("Nuvoton NPCM ADC Driver");
352 MODULE_AUTHOR("Tomer Maimon <tomer.maimon@nuvoton.com>");
353 MODULE_LICENSE("GPL v2");
354