2 * Driver for the ADC present in the Atmel AT91 evaluation boards.
4 * Copyright 2011 Free Electrons
6 * Licensed under the GPLv2 or later.
9 #include <linux/bitmap.h>
10 #include <linux/bitops.h>
11 #include <linux/clk.h>
12 #include <linux/err.h>
14 #include <linux/interrupt.h>
15 #include <linux/jiffies.h>
16 #include <linux/kernel.h>
17 #include <linux/module.h>
19 #include <linux/of_device.h>
20 #include <linux/platform_device.h>
21 #include <linux/sched.h>
22 #include <linux/slab.h>
23 #include <linux/wait.h>
25 #include <linux/platform_data/at91_adc.h>
27 #include <linux/iio/iio.h>
28 #include <linux/iio/buffer.h>
29 #include <linux/iio/trigger.h>
30 #include <linux/iio/trigger_consumer.h>
31 #include <linux/iio/triggered_buffer.h>
33 #include <mach/at91_adc.h>
35 #define AT91_ADC_CHAN(st, ch) \
36 (st->registers->channel_base + (ch * 4))
37 #define at91_adc_readl(st, reg) \
38 (readl_relaxed(st->reg_base + reg))
39 #define at91_adc_writel(st, reg, val) \
40 (writel_relaxed(val, st->reg_base + reg))
42 struct at91_adc_caps {
43 struct at91_adc_reg_desc registers;
46 struct at91_adc_state {
49 unsigned long channels_mask;
56 void __iomem *reg_base;
57 struct at91_adc_reg_desc *registers;
61 struct iio_trigger **trig;
62 struct at91_adc_trigger *trigger_list;
66 u32 res; /* resolution used for convertions */
67 bool low_res; /* the resolution corresponds to the lowest one */
68 wait_queue_head_t wq_data_avail;
69 struct at91_adc_caps *caps;
72 static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
74 struct iio_poll_func *pf = p;
75 struct iio_dev *idev = pf->indio_dev;
76 struct at91_adc_state *st = iio_priv(idev);
79 for (i = 0; i < idev->masklength; i++) {
80 if (!test_bit(i, idev->active_scan_mask))
82 st->buffer[j] = at91_adc_readl(st, AT91_ADC_CHAN(st, i));
86 if (idev->scan_timestamp) {
87 s64 *timestamp = (s64 *)((u8 *)st->buffer +
88 ALIGN(j, sizeof(s64)));
89 *timestamp = pf->timestamp;
92 iio_push_to_buffers(idev, st->buffer);
94 iio_trigger_notify_done(idev->trig);
96 /* Needed to ACK the DRDY interruption */
97 at91_adc_readl(st, AT91_ADC_LCDR);
104 static irqreturn_t at91_adc_eoc_trigger(int irq, void *private)
106 struct iio_dev *idev = private;
107 struct at91_adc_state *st = iio_priv(idev);
108 u32 status = at91_adc_readl(st, st->registers->status_register);
110 if (!(status & st->registers->drdy_mask))
113 if (iio_buffer_enabled(idev)) {
114 disable_irq_nosync(irq);
115 iio_trigger_poll(idev->trig, iio_get_time_ns());
117 st->last_value = at91_adc_readl(st, AT91_ADC_LCDR);
119 wake_up_interruptible(&st->wq_data_avail);
125 static int at91_adc_channel_init(struct iio_dev *idev)
127 struct at91_adc_state *st = iio_priv(idev);
128 struct iio_chan_spec *chan_array, *timestamp;
131 idev->num_channels = bitmap_weight(&st->channels_mask,
132 st->num_channels) + 1;
134 chan_array = devm_kzalloc(&idev->dev,
135 ((idev->num_channels + 1) *
136 sizeof(struct iio_chan_spec)),
142 for_each_set_bit(bit, &st->channels_mask, st->num_channels) {
143 struct iio_chan_spec *chan = chan_array + idx;
145 chan->type = IIO_VOLTAGE;
148 chan->scan_index = idx;
149 chan->scan_type.sign = 'u';
150 chan->scan_type.realbits = st->res;
151 chan->scan_type.storagebits = 16;
152 chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
153 chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
156 timestamp = chan_array + idx;
158 timestamp->type = IIO_TIMESTAMP;
159 timestamp->channel = -1;
160 timestamp->scan_index = idx;
161 timestamp->scan_type.sign = 's';
162 timestamp->scan_type.realbits = 64;
163 timestamp->scan_type.storagebits = 64;
165 idev->channels = chan_array;
166 return idev->num_channels;
169 static u8 at91_adc_get_trigger_value_by_name(struct iio_dev *idev,
170 struct at91_adc_trigger *triggers,
171 const char *trigger_name)
173 struct at91_adc_state *st = iio_priv(idev);
177 for (i = 0; i < st->trigger_number; i++) {
178 char *name = kasprintf(GFP_KERNEL,
186 if (strcmp(trigger_name, name) == 0) {
187 value = triggers[i].value;
198 static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
200 struct iio_dev *idev = iio_trigger_get_drvdata(trig);
201 struct at91_adc_state *st = iio_priv(idev);
202 struct iio_buffer *buffer = idev->buffer;
203 struct at91_adc_reg_desc *reg = st->registers;
204 u32 status = at91_adc_readl(st, reg->trigger_register);
208 value = at91_adc_get_trigger_value_by_name(idev,
215 st->buffer = kmalloc(idev->scan_bytes, GFP_KERNEL);
216 if (st->buffer == NULL)
219 at91_adc_writel(st, reg->trigger_register,
222 for_each_set_bit(bit, buffer->scan_mask,
224 struct iio_chan_spec const *chan = idev->channels + bit;
225 at91_adc_writel(st, AT91_ADC_CHER,
226 AT91_ADC_CH(chan->channel));
229 at91_adc_writel(st, AT91_ADC_IER, reg->drdy_mask);
232 at91_adc_writel(st, AT91_ADC_IDR, reg->drdy_mask);
234 at91_adc_writel(st, reg->trigger_register,
237 for_each_set_bit(bit, buffer->scan_mask,
239 struct iio_chan_spec const *chan = idev->channels + bit;
240 at91_adc_writel(st, AT91_ADC_CHDR,
241 AT91_ADC_CH(chan->channel));
249 static const struct iio_trigger_ops at91_adc_trigger_ops = {
250 .owner = THIS_MODULE,
251 .set_trigger_state = &at91_adc_configure_trigger,
254 static struct iio_trigger *at91_adc_allocate_trigger(struct iio_dev *idev,
255 struct at91_adc_trigger *trigger)
257 struct iio_trigger *trig;
260 trig = iio_trigger_alloc("%s-dev%d-%s", idev->name,
261 idev->id, trigger->name);
265 trig->dev.parent = idev->dev.parent;
266 iio_trigger_set_drvdata(trig, idev);
267 trig->ops = &at91_adc_trigger_ops;
269 ret = iio_trigger_register(trig);
276 static int at91_adc_trigger_init(struct iio_dev *idev)
278 struct at91_adc_state *st = iio_priv(idev);
281 st->trig = devm_kzalloc(&idev->dev,
282 st->trigger_number * sizeof(st->trig),
285 if (st->trig == NULL) {
290 for (i = 0; i < st->trigger_number; i++) {
291 if (st->trigger_list[i].is_external && !(st->use_external))
294 st->trig[i] = at91_adc_allocate_trigger(idev,
295 st->trigger_list + i);
296 if (st->trig[i] == NULL) {
298 "Could not allocate trigger %d\n", i);
307 for (i--; i >= 0; i--) {
308 iio_trigger_unregister(st->trig[i]);
309 iio_trigger_free(st->trig[i]);
315 static void at91_adc_trigger_remove(struct iio_dev *idev)
317 struct at91_adc_state *st = iio_priv(idev);
320 for (i = 0; i < st->trigger_number; i++) {
321 iio_trigger_unregister(st->trig[i]);
322 iio_trigger_free(st->trig[i]);
326 static int at91_adc_buffer_init(struct iio_dev *idev)
328 return iio_triggered_buffer_setup(idev, &iio_pollfunc_store_time,
329 &at91_adc_trigger_handler, NULL);
332 static void at91_adc_buffer_remove(struct iio_dev *idev)
334 iio_triggered_buffer_cleanup(idev);
337 static int at91_adc_read_raw(struct iio_dev *idev,
338 struct iio_chan_spec const *chan,
339 int *val, int *val2, long mask)
341 struct at91_adc_state *st = iio_priv(idev);
345 case IIO_CHAN_INFO_RAW:
346 mutex_lock(&st->lock);
348 at91_adc_writel(st, AT91_ADC_CHER,
349 AT91_ADC_CH(chan->channel));
350 at91_adc_writel(st, AT91_ADC_IER, st->registers->drdy_mask);
351 at91_adc_writel(st, AT91_ADC_CR, AT91_ADC_START);
353 ret = wait_event_interruptible_timeout(st->wq_data_avail,
355 msecs_to_jiffies(1000));
359 mutex_unlock(&st->lock);
363 *val = st->last_value;
365 at91_adc_writel(st, AT91_ADC_CHDR,
366 AT91_ADC_CH(chan->channel));
367 at91_adc_writel(st, AT91_ADC_IDR, st->registers->drdy_mask);
371 mutex_unlock(&st->lock);
374 case IIO_CHAN_INFO_SCALE:
375 *val = (st->vref_mv * 1000) >> chan->scan_type.realbits;
377 return IIO_VAL_INT_PLUS_MICRO;
384 static int at91_adc_of_get_resolution(struct at91_adc_state *st,
385 struct platform_device *pdev)
387 struct iio_dev *idev = iio_priv_to_dev(st);
388 struct device_node *np = pdev->dev.of_node;
389 int count, i, ret = 0;
393 count = of_property_count_strings(np, "atmel,adc-res-names");
395 dev_err(&idev->dev, "You must specified at least two resolution names for "
396 "adc-res-names property in the DT\n");
400 resolutions = kmalloc(count * sizeof(*resolutions), GFP_KERNEL);
404 if (of_property_read_u32_array(np, "atmel,adc-res", resolutions, count)) {
405 dev_err(&idev->dev, "Missing adc-res property in the DT.\n");
410 if (of_property_read_string(np, "atmel,adc-use-res", (const char **)&res_name))
411 res_name = "highres";
413 for (i = 0; i < count; i++) {
414 if (of_property_read_string_index(np, "atmel,adc-res-names", i, (const char **)&s))
417 if (strcmp(res_name, s))
420 st->res = resolutions[i];
421 if (!strcmp(res_name, "lowres"))
426 dev_info(&idev->dev, "Resolution used: %u bits\n", st->res);
430 dev_err(&idev->dev, "There is no resolution for %s\n", res_name);
437 static const struct of_device_id at91_adc_dt_ids[];
439 static int at91_adc_probe_dt(struct at91_adc_state *st,
440 struct platform_device *pdev)
442 struct iio_dev *idev = iio_priv_to_dev(st);
443 struct device_node *node = pdev->dev.of_node;
444 struct device_node *trig_node;
451 st->caps = (struct at91_adc_caps *)
452 of_match_device(at91_adc_dt_ids, &pdev->dev)->data;
454 st->use_external = of_property_read_bool(node, "atmel,adc-use-external-triggers");
456 if (of_property_read_u32(node, "atmel,adc-channels-used", &prop)) {
457 dev_err(&idev->dev, "Missing adc-channels-used property in the DT.\n");
461 st->channels_mask = prop;
463 if (of_property_read_u32(node, "atmel,adc-num-channels", &prop)) {
464 dev_err(&idev->dev, "Missing adc-num-channels property in the DT.\n");
468 st->num_channels = prop;
470 st->sleep_mode = of_property_read_bool(node, "atmel,adc-sleep-mode");
472 if (of_property_read_u32(node, "atmel,adc-startup-time", &prop)) {
473 dev_err(&idev->dev, "Missing adc-startup-time property in the DT.\n");
477 st->startup_time = prop;
480 of_property_read_u32(node, "atmel,adc-sample-hold-time", &prop);
481 st->sample_hold_time = prop;
483 if (of_property_read_u32(node, "atmel,adc-vref", &prop)) {
484 dev_err(&idev->dev, "Missing adc-vref property in the DT.\n");
490 ret = at91_adc_of_get_resolution(st, pdev);
494 st->registers = &st->caps->registers;
495 st->trigger_number = of_get_child_count(node);
496 st->trigger_list = devm_kzalloc(&idev->dev, st->trigger_number *
497 sizeof(struct at91_adc_trigger),
499 if (!st->trigger_list) {
500 dev_err(&idev->dev, "Could not allocate trigger list memory.\n");
505 for_each_child_of_node(node, trig_node) {
506 struct at91_adc_trigger *trig = st->trigger_list + i;
509 if (of_property_read_string(trig_node, "trigger-name", &name)) {
510 dev_err(&idev->dev, "Missing trigger-name property in the DT.\n");
516 if (of_property_read_u32(trig_node, "trigger-value", &prop)) {
517 dev_err(&idev->dev, "Missing trigger-value property in the DT.\n");
522 trig->is_external = of_property_read_bool(trig_node, "trigger-external");
532 static int at91_adc_probe_pdata(struct at91_adc_state *st,
533 struct platform_device *pdev)
535 struct at91_adc_data *pdata = pdev->dev.platform_data;
540 st->use_external = pdata->use_external_triggers;
541 st->vref_mv = pdata->vref;
542 st->channels_mask = pdata->channels_used;
543 st->num_channels = pdata->num_channels;
544 st->startup_time = pdata->startup_time;
545 st->trigger_number = pdata->trigger_number;
546 st->trigger_list = pdata->trigger_list;
547 st->registers = pdata->registers;
552 static const struct iio_info at91_adc_info = {
553 .driver_module = THIS_MODULE,
554 .read_raw = &at91_adc_read_raw,
557 static int at91_adc_probe(struct platform_device *pdev)
559 unsigned int prsc, mstrclk, ticks, adc_clk, shtim;
561 struct iio_dev *idev;
562 struct at91_adc_state *st;
563 struct resource *res;
566 idev = devm_iio_device_alloc(&pdev->dev, sizeof(struct at91_adc_state));
572 if (pdev->dev.of_node)
573 ret = at91_adc_probe_dt(st, pdev);
575 ret = at91_adc_probe_pdata(st, pdev);
578 dev_err(&pdev->dev, "No platform data available.\n");
582 platform_set_drvdata(pdev, idev);
584 idev->dev.parent = &pdev->dev;
585 idev->name = dev_name(&pdev->dev);
586 idev->modes = INDIO_DIRECT_MODE;
587 idev->info = &at91_adc_info;
589 st->irq = platform_get_irq(pdev, 0);
591 dev_err(&pdev->dev, "No IRQ ID is designated\n");
595 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
597 st->reg_base = devm_ioremap_resource(&pdev->dev, res);
598 if (IS_ERR(st->reg_base)) {
599 return PTR_ERR(st->reg_base);
603 * Disable all IRQs before setting up the handler
605 at91_adc_writel(st, AT91_ADC_CR, AT91_ADC_SWRST);
606 at91_adc_writel(st, AT91_ADC_IDR, 0xFFFFFFFF);
607 ret = request_irq(st->irq,
608 at91_adc_eoc_trigger,
610 pdev->dev.driver->name,
613 dev_err(&pdev->dev, "Failed to allocate IRQ.\n");
617 st->clk = devm_clk_get(&pdev->dev, "adc_clk");
618 if (IS_ERR(st->clk)) {
619 dev_err(&pdev->dev, "Failed to get the clock.\n");
620 ret = PTR_ERR(st->clk);
624 ret = clk_prepare_enable(st->clk);
627 "Could not prepare or enable the clock.\n");
631 st->adc_clk = devm_clk_get(&pdev->dev, "adc_op_clk");
632 if (IS_ERR(st->adc_clk)) {
633 dev_err(&pdev->dev, "Failed to get the ADC clock.\n");
634 ret = PTR_ERR(st->adc_clk);
635 goto error_disable_clk;
638 ret = clk_prepare_enable(st->adc_clk);
641 "Could not prepare or enable the ADC clock.\n");
642 goto error_disable_clk;
646 * Prescaler rate computation using the formula from the Atmel's
647 * datasheet : ADC Clock = MCK / ((Prescaler + 1) * 2), ADC Clock being
648 * specified by the electrical characteristics of the board.
650 mstrclk = clk_get_rate(st->clk);
651 adc_clk = clk_get_rate(st->adc_clk);
652 prsc = (mstrclk / (2 * adc_clk)) - 1;
654 if (!st->startup_time) {
655 dev_err(&pdev->dev, "No startup time available.\n");
657 goto error_disable_adc_clk;
661 * Number of ticks needed to cover the startup time of the ADC as
662 * defined in the electrical characteristics of the board, divided by 8.
663 * The formula thus is : Startup Time = (ticks + 1) * 8 / ADC Clock
665 ticks = round_up((st->startup_time * adc_clk /
666 1000000) - 1, 8) / 8;
668 * a minimal Sample and Hold Time is necessary for the ADC to guarantee
669 * the best converted final value between two channels selection
670 * The formula thus is : Sample and Hold Time = (shtim + 1) / ADCClock
672 shtim = round_up((st->sample_hold_time * adc_clk /
675 reg = AT91_ADC_PRESCAL_(prsc) & st->registers->mr_prescal_mask;
676 reg |= AT91_ADC_STARTUP_(ticks) & st->registers->mr_startup_mask;
678 reg |= AT91_ADC_LOWRES;
680 reg |= AT91_ADC_SLEEP;
681 reg |= AT91_ADC_SHTIM_(shtim) & AT91_ADC_SHTIM;
682 at91_adc_writel(st, AT91_ADC_MR, reg);
684 /* Setup the ADC channels available on the board */
685 ret = at91_adc_channel_init(idev);
687 dev_err(&pdev->dev, "Couldn't initialize the channels.\n");
688 goto error_disable_adc_clk;
691 init_waitqueue_head(&st->wq_data_avail);
692 mutex_init(&st->lock);
694 ret = at91_adc_buffer_init(idev);
696 dev_err(&pdev->dev, "Couldn't initialize the buffer.\n");
697 goto error_disable_adc_clk;
700 ret = at91_adc_trigger_init(idev);
702 dev_err(&pdev->dev, "Couldn't setup the triggers.\n");
703 goto error_unregister_buffer;
706 ret = iio_device_register(idev);
708 dev_err(&pdev->dev, "Couldn't register the device.\n");
709 goto error_remove_triggers;
714 error_remove_triggers:
715 at91_adc_trigger_remove(idev);
716 error_unregister_buffer:
717 at91_adc_buffer_remove(idev);
718 error_disable_adc_clk:
719 clk_disable_unprepare(st->adc_clk);
721 clk_disable_unprepare(st->clk);
723 free_irq(st->irq, idev);
727 static int at91_adc_remove(struct platform_device *pdev)
729 struct iio_dev *idev = platform_get_drvdata(pdev);
730 struct at91_adc_state *st = iio_priv(idev);
732 iio_device_unregister(idev);
733 at91_adc_trigger_remove(idev);
734 at91_adc_buffer_remove(idev);
735 clk_disable_unprepare(st->adc_clk);
736 clk_disable_unprepare(st->clk);
737 free_irq(st->irq, idev);
743 static struct at91_adc_caps at91sam9260_caps = {
745 .channel_base = AT91_ADC_CHR(0),
746 .drdy_mask = AT91_ADC_DRDY,
747 .status_register = AT91_ADC_SR,
748 .trigger_register = AT91_ADC_TRGR_9260,
749 .mr_prescal_mask = AT91_ADC_PRESCAL_9260,
750 .mr_startup_mask = AT91_ADC_STARTUP_9260,
754 static struct at91_adc_caps at91sam9g45_caps = {
756 .channel_base = AT91_ADC_CHR(0),
757 .drdy_mask = AT91_ADC_DRDY,
758 .status_register = AT91_ADC_SR,
759 .trigger_register = AT91_ADC_TRGR_9G45,
760 .mr_prescal_mask = AT91_ADC_PRESCAL_9G45,
761 .mr_startup_mask = AT91_ADC_STARTUP_9G45,
765 static struct at91_adc_caps at91sam9x5_caps = {
767 .channel_base = AT91_ADC_CDR0_9X5,
768 .drdy_mask = AT91_ADC_SR_DRDY_9X5,
769 .status_register = AT91_ADC_SR_9X5,
770 .trigger_register = AT91_ADC_TRGR_9X5,
771 /* prescal mask is same as 9G45 */
772 .mr_prescal_mask = AT91_ADC_PRESCAL_9G45,
773 .mr_startup_mask = AT91_ADC_STARTUP_9X5,
777 static const struct of_device_id at91_adc_dt_ids[] = {
778 { .compatible = "atmel,at91sam9260-adc", .data = &at91sam9260_caps },
779 { .compatible = "atmel,at91sam9g45-adc", .data = &at91sam9g45_caps },
780 { .compatible = "atmel,at91sam9x5-adc", .data = &at91sam9x5_caps },
783 MODULE_DEVICE_TABLE(of, at91_adc_dt_ids);
786 static struct platform_driver at91_adc_driver = {
787 .probe = at91_adc_probe,
788 .remove = at91_adc_remove,
791 .of_match_table = of_match_ptr(at91_adc_dt_ids),
795 module_platform_driver(at91_adc_driver);
797 MODULE_LICENSE("GPL");
798 MODULE_DESCRIPTION("Atmel AT91 ADC Driver");
799 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");