1// SPDX-License-Identifier: GPL-2.0-only
  2//
  3// ALSA SoC glue to use IIO devices as audio components
  4//
  5// Copyright 2023 CS GROUP France
  6//
  7// Author: Herve Codina <herve.codina@bootlin.com>
  8
  9#include <linux/cleanup.h>
 10#include <linux/iio/consumer.h>
 11#include <linux/minmax.h>
 12#include <linux/mod_devicetable.h>
 13#include <linux/platform_device.h>
 14#include <linux/slab.h>
 15#include <linux/string_helpers.h>
 16
 17#include <sound/soc.h>
 18#include <sound/tlv.h>
 19
 20struct audio_iio_aux_chan {
 21	struct iio_channel *iio_chan;
 22	const char *name;
 23	int max;
 24	int min;
 25	bool is_invert_range;
 26};
 27
 28struct audio_iio_aux {
 29	struct device *dev;
 30	unsigned int num_chans;
 31	struct audio_iio_aux_chan chans[]  __counted_by(num_chans);
 32};
 33
 34static int audio_iio_aux_info_volsw(struct snd_kcontrol *kcontrol,
 35				    struct snd_ctl_elem_info *uinfo)
 36{
 37	struct audio_iio_aux_chan *chan = (struct audio_iio_aux_chan *)kcontrol->private_value;
 38
 39	uinfo->count = 1;
 40	uinfo->value.integer.min = 0;
 41	uinfo->value.integer.max = chan->max - chan->min;
 42	uinfo->type = (uinfo->value.integer.max == 1) ?
 43			SNDRV_CTL_ELEM_TYPE_BOOLEAN : SNDRV_CTL_ELEM_TYPE_INTEGER;
 44	return 0;
 45}
 46
 47static int audio_iio_aux_get_volsw(struct snd_kcontrol *kcontrol,
 48				   struct snd_ctl_elem_value *ucontrol)
 49{
 50	struct audio_iio_aux_chan *chan = (struct audio_iio_aux_chan *)kcontrol->private_value;
 51	int max = chan->max;
 52	int min = chan->min;
 53	bool invert_range = chan->is_invert_range;
 54	int ret;
 55	int val;
 56
 57	ret = iio_read_channel_raw(chan->iio_chan, &val);
 58	if (ret < 0)
 59		return ret;
 60
 61	ucontrol->value.integer.value[0] = val - min;
 62	if (invert_range)
 63		ucontrol->value.integer.value[0] = max - ucontrol->value.integer.value[0];
 64
 65	return 0;
 66}
 67
 68static int audio_iio_aux_put_volsw(struct snd_kcontrol *kcontrol,
 69				   struct snd_ctl_elem_value *ucontrol)
 70{
 71	struct audio_iio_aux_chan *chan = (struct audio_iio_aux_chan *)kcontrol->private_value;
 72	int max = chan->max;
 73	int min = chan->min;
 74	bool invert_range = chan->is_invert_range;
 75	int val;
 76	int ret;
 77	int tmp;
 78
 79	val = ucontrol->value.integer.value[0];
 80	if (val < 0)
 81		return -EINVAL;
 82	if (val > max - min)
 83		return -EINVAL;
 84
 85	val = val + min;
 86	if (invert_range)
 87		val = max - val;
 88
 89	ret = iio_read_channel_raw(chan->iio_chan, &tmp);
 90	if (ret < 0)
 91		return ret;
 92
 93	if (tmp == val)
 94		return 0;
 95
 96	ret = iio_write_channel_raw(chan->iio_chan, val);
 97	if (ret)
 98		return ret;
 99
100	return 1; /* The value changed */
101}
102
103static int audio_iio_aux_add_controls(struct snd_soc_component *component,
104				      struct audio_iio_aux_chan *chan)
105{
106	struct snd_kcontrol_new control = {
107		.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
108		.name = chan->name,
109		.info = audio_iio_aux_info_volsw,
110		.get = audio_iio_aux_get_volsw,
111		.put = audio_iio_aux_put_volsw,
112		.private_value = (unsigned long)chan,
113	};
114
115	return snd_soc_add_component_controls(component, &control, 1);
116}
117
118/*
119 * These data could be on stack but they are pretty big.
120 * As ASoC internally copy them and protect them against concurrent accesses
121 * (snd_soc_bind_card() protects using client_mutex), keep them in the global
122 * data area.
123 */
124static struct snd_soc_dapm_widget widgets[3];
125static struct snd_soc_dapm_route routes[2];
126
127/* Be sure sizes are correct (need 3 widgets and 2 routes) */
128static_assert(ARRAY_SIZE(widgets) >= 3, "3 widgets are needed");
129static_assert(ARRAY_SIZE(routes) >= 2, "2 routes are needed");
130
131static int audio_iio_aux_add_dapms(struct snd_soc_component *component,
132				   struct audio_iio_aux_chan *chan)
133{
134	struct snd_soc_dapm_context *dapm = snd_soc_component_get_dapm(component);
135	int ret;
136
137	/* Allocated names are not needed afterwards (duplicated in ASoC internals) */
138	char *input_name __free(kfree) = kasprintf(GFP_KERNEL, "%s IN", chan->name);
139	if (!input_name)
140		return -ENOMEM;
141
142	char *output_name __free(kfree) = kasprintf(GFP_KERNEL, "%s OUT", chan->name);
143	if (!output_name)
144		return -ENOMEM;
145
146	char *pga_name __free(kfree) = kasprintf(GFP_KERNEL, "%s PGA", chan->name);
147	if (!pga_name)
148		return -ENOMEM;
149
150	widgets[0] = SND_SOC_DAPM_INPUT(input_name);
151	widgets[1] = SND_SOC_DAPM_OUTPUT(output_name);
152	widgets[2] = SND_SOC_DAPM_PGA(pga_name, SND_SOC_NOPM, 0, 0, NULL, 0);
153	ret = snd_soc_dapm_new_controls(dapm, widgets, 3);
154	if (ret)
155		return ret;
156
157	routes[0].sink = pga_name;
158	routes[0].control = NULL;
159	routes[0].source = input_name;
160	routes[1].sink = output_name;
161	routes[1].control = NULL;
162	routes[1].source = pga_name;
163
164	return snd_soc_dapm_add_routes(dapm, routes, 2);
165}
166
167static int audio_iio_aux_component_probe(struct snd_soc_component *component)
168{
169	struct audio_iio_aux *iio_aux = snd_soc_component_get_drvdata(component);
170	struct audio_iio_aux_chan *chan;
171	int ret;
172	int i;
173
174	for (i = 0; i < iio_aux->num_chans; i++) {
175		chan = iio_aux->chans + i;
176
177		ret = iio_read_max_channel_raw(chan->iio_chan, &chan->max);
178		if (ret)
179			return dev_err_probe(component->dev, ret,
180					     "chan[%d] %s: Cannot get max raw value\n",
181					     i, chan->name);
182
183		ret = iio_read_min_channel_raw(chan->iio_chan, &chan->min);
184		if (ret)
185			return dev_err_probe(component->dev, ret,
186					     "chan[%d] %s: Cannot get min raw value\n",
187					     i, chan->name);
188
189		if (chan->min > chan->max) {
190			/*
191			 * This should never happen but to avoid any check
192			 * later, just swap values here to ensure that the
193			 * minimum value is lower than the maximum value.
194			 */
195			dev_dbg(component->dev, "chan[%d] %s: Swap min and max\n",
196				i, chan->name);
197			swap(chan->min, chan->max);
198		}
199
200		/* Set initial value */
201		ret = iio_write_channel_raw(chan->iio_chan,
202					    chan->is_invert_range ? chan->max : chan->min);
203		if (ret)
204			return dev_err_probe(component->dev, ret,
205					     "chan[%d] %s: Cannot set initial value\n",
206					     i, chan->name);
207
208		ret = audio_iio_aux_add_controls(component, chan);
209		if (ret)
210			return ret;
211
212		ret = audio_iio_aux_add_dapms(component, chan);
213		if (ret)
214			return ret;
215
216		dev_dbg(component->dev, "chan[%d]: Added %s (min=%d, max=%d, invert=%s)\n",
217			i, chan->name, chan->min, chan->max,
218			str_on_off(chan->is_invert_range));
219	}
220
221	return 0;
222}
223
224static const struct snd_soc_component_driver audio_iio_aux_component_driver = {
225	.probe = audio_iio_aux_component_probe,
226};
227
228static int audio_iio_aux_probe(struct platform_device *pdev)
229{
230	struct audio_iio_aux_chan *iio_aux_chan;
231	struct device *dev = &pdev->dev;
232	struct audio_iio_aux *iio_aux;
233	int count;
234	int ret;
235	int i;
236
237	count = device_property_string_array_count(dev, "io-channel-names");
238	if (count < 0)
239		return dev_err_probe(dev, count, "failed to count io-channel-names\n");
240
241	iio_aux = devm_kzalloc(dev, struct_size(iio_aux, chans, count), GFP_KERNEL);
242	if (!iio_aux)
243		return -ENOMEM;
244
245	iio_aux->dev = dev;
246
247	iio_aux->num_chans = count;
248
249	const char **names __free(kfree) = kcalloc(iio_aux->num_chans,
250						   sizeof(*names),
251						   GFP_KERNEL);
252	if (!names)
253		return -ENOMEM;
254
255	u32 *invert_ranges __free(kfree) = kcalloc(iio_aux->num_chans,
256						   sizeof(*invert_ranges),
257						   GFP_KERNEL);
258	if (!invert_ranges)
259		return -ENOMEM;
260
261	ret = device_property_read_string_array(dev, "io-channel-names",
262						names, iio_aux->num_chans);
263	if (ret < 0)
264		return dev_err_probe(dev, ret, "failed to read io-channel-names\n");
265
266	/*
267	 * snd-control-invert-range is optional and can contain fewer items
268	 * than the number of channels. Unset values default to 0.
269	 */
270	count = device_property_count_u32(dev, "snd-control-invert-range");
271	if (count > 0) {
272		count = min_t(unsigned int, count, iio_aux->num_chans);
273		ret = device_property_read_u32_array(dev, "snd-control-invert-range",
274						     invert_ranges, count);
275		if (ret < 0)
276			return dev_err_probe(dev, ret, "failed to read snd-control-invert-range\n");
277	}
278
279	for (i = 0; i < iio_aux->num_chans; i++) {
280		iio_aux_chan = iio_aux->chans + i;
281		iio_aux_chan->name = names[i];
282		iio_aux_chan->is_invert_range = invert_ranges[i];
283
284		iio_aux_chan->iio_chan = devm_iio_channel_get(dev, iio_aux_chan->name);
285		if (IS_ERR(iio_aux_chan->iio_chan))
286			return dev_err_probe(dev, PTR_ERR(iio_aux_chan->iio_chan),
287					     "get IIO channel '%s' failed\n",
288					     iio_aux_chan->name);
289	}
290
291	platform_set_drvdata(pdev, iio_aux);
292
293	return devm_snd_soc_register_component(dev, &audio_iio_aux_component_driver,
294					       NULL, 0);
295}
296
297static const struct of_device_id audio_iio_aux_ids[] = {
298	{ .compatible = "audio-iio-aux" },
299	{ }
300};
301MODULE_DEVICE_TABLE(of, audio_iio_aux_ids);
302
303static struct platform_driver audio_iio_aux_driver = {
304	.driver = {
305		.name = "audio-iio-aux",
306		.of_match_table = audio_iio_aux_ids,
307	},
308	.probe = audio_iio_aux_probe,
309};
310module_platform_driver(audio_iio_aux_driver);
311
312MODULE_AUTHOR("Herve Codina <herve.codina@bootlin.com>");
313MODULE_DESCRIPTION("IIO ALSA SoC aux driver");
314MODULE_LICENSE("GPL");