// SPDX-License-Identifier: GPL-2.0 /* * Texas Instruments TSC2046 SPI ADC driver * * Copyright (c) 2021 Oleksij Rempel , Pengutronix */ #include #include #include #include #include #include #include #include #include /* * The PENIRQ of TSC2046 controller is implemented as level shifter attached to * the X+ line. If voltage of the X+ line reaches a specific level the IRQ will * be activated or deactivated. * To make this kind of IRQ reusable as trigger following additions were * implemented: * - rate limiting: * For typical touchscreen use case, we need to trigger about each 10ms. * - hrtimer: * Continue triggering at least once after the IRQ was deactivated. Then * deactivate this trigger to stop sampling in order to reduce power * consumption. */ #define TI_TSC2046_NAME "tsc2046" /* This driver doesn't aim at the peak continuous sample rate */ #define TI_TSC2046_MAX_SAMPLE_RATE 125000 #define TI_TSC2046_SAMPLE_BITS \ BITS_PER_TYPE(struct tsc2046_adc_atom) #define TI_TSC2046_MAX_CLK_FREQ \ (TI_TSC2046_MAX_SAMPLE_RATE * TI_TSC2046_SAMPLE_BITS) #define TI_TSC2046_SAMPLE_INTERVAL_US 10000 #define TI_TSC2046_START BIT(7) #define TI_TSC2046_ADDR GENMASK(6, 4) #define TI_TSC2046_ADDR_TEMP1 7 #define TI_TSC2046_ADDR_AUX 6 #define TI_TSC2046_ADDR_X 5 #define TI_TSC2046_ADDR_Z2 4 #define TI_TSC2046_ADDR_Z1 3 #define TI_TSC2046_ADDR_VBAT 2 #define TI_TSC2046_ADDR_Y 1 #define TI_TSC2046_ADDR_TEMP0 0 /* * The mode bit sets the resolution of the ADC. With this bit low, the next * conversion has 12-bit resolution, whereas with this bit high, the next * conversion has 8-bit resolution. This driver is optimized for 12-bit mode. * So, for this driver, this bit should stay zero. */ #define TI_TSC2046_8BIT_MODE BIT(3) /* * SER/DFR - The SER/DFR bit controls the reference mode, either single-ended * (high) or differential (low). */ #define TI_TSC2046_SER BIT(2) /* * If VREF_ON and ADC_ON are both zero, then the chip operates in * auto-wake/suspend mode. In most case this bits should stay zero. */ #define TI_TSC2046_PD1_VREF_ON BIT(1) #define TI_TSC2046_PD0_ADC_ON BIT(0) /* * All supported devices can do 8 or 12bit resolution. This driver * supports only 12bit mode, here we have a 16bit data transfer, where * the MSB and the 3 LSB are 0. */ #define TI_TSC2046_DATA_12BIT GENMASK(14, 3) #define TI_TSC2046_MAX_CHAN 8 /* Represents a HW sample */ struct tsc2046_adc_atom { /* * Command transmitted to the controller. This field is empty on the RX * buffer. */ u8 cmd; /* * Data received from the controller. This field is empty for the TX * buffer */ __be16 data; } __packed; /* Layout of atomic buffers within big buffer */ struct tsc2046_adc_group_layout { /* Group offset within the SPI RX buffer */ unsigned int offset; /* * Amount of tsc2046_adc_atom structs within the same command gathered * within same group. */ unsigned int count; /* * Settling samples (tsc2046_adc_atom structs) which should be skipped * before good samples will start. */ unsigned int skip; }; struct tsc2046_adc_dcfg { const struct iio_chan_spec *channels; unsigned int num_channels; }; struct tsc2046_adc_ch_cfg { unsigned int settling_time_us; unsigned int oversampling_ratio; }; struct tsc2046_adc_priv { struct spi_device *spi; const struct tsc2046_adc_dcfg *dcfg; struct iio_trigger *trig; struct hrtimer trig_timer; spinlock_t trig_lock; unsigned int trig_more_count; struct spi_transfer xfer; struct spi_message msg; struct { /* Scan data for each channel */ u16 data[TI_TSC2046_MAX_CHAN]; /* Timestamp */ s64 ts __aligned(8); } scan_buf; /* * Lock to protect the layout and the SPI transfer buffer. * tsc2046_adc_group_layout can be changed within update_scan_mode(), * in this case the l[] and tx/rx buffer will be out of sync to each * other. */ struct mutex slock; struct tsc2046_adc_group_layout l[TI_TSC2046_MAX_CHAN]; struct tsc2046_adc_atom *rx; struct tsc2046_adc_atom *tx; struct tsc2046_adc_atom *rx_one; struct tsc2046_adc_atom *tx_one; unsigned int count; unsigned int groups; u32 effective_speed_hz; u32 scan_interval_us; u32 time_per_scan_us; u32 time_per_bit_ns; struct tsc2046_adc_ch_cfg ch_cfg[TI_TSC2046_MAX_CHAN]; }; #define TI_TSC2046_V_CHAN(index, bits, name) \ { \ .type = IIO_VOLTAGE, \ .indexed = 1, \ .channel = index, \ .datasheet_name = "#name", \ .scan_index = index, \ .scan_type = { \ .sign = 'u', \ .realbits = bits, \ .storagebits = 16, \ .endianness = IIO_CPU, \ }, \ } #define DECLARE_TI_TSC2046_8_CHANNELS(name, bits) \ const struct iio_chan_spec name ## _channels[] = { \ TI_TSC2046_V_CHAN(0, bits, TEMP0), \ TI_TSC2046_V_CHAN(1, bits, Y), \ TI_TSC2046_V_CHAN(2, bits, VBAT), \ TI_TSC2046_V_CHAN(3, bits, Z1), \ TI_TSC2046_V_CHAN(4, bits, Z2), \ TI_TSC2046_V_CHAN(5, bits, X), \ TI_TSC2046_V_CHAN(6, bits, AUX), \ TI_TSC2046_V_CHAN(7, bits, TEMP1), \ IIO_CHAN_SOFT_TIMESTAMP(8), \ } static DECLARE_TI_TSC2046_8_CHANNELS(tsc2046_adc, 12); static const struct tsc2046_adc_dcfg tsc2046_adc_dcfg_tsc2046e = { .channels = tsc2046_adc_channels, .num_channels = ARRAY_SIZE(tsc2046_adc_channels), }; /* * Convert time to a number of samples which can be transferred within this * time. */ static unsigned int tsc2046_adc_time_to_count(struct tsc2046_adc_priv *priv, unsigned long time) { unsigned int bit_count, sample_count; bit_count = DIV_ROUND_UP(time * NSEC_PER_USEC, priv->time_per_bit_ns); sample_count = DIV_ROUND_UP(bit_count, TI_TSC2046_SAMPLE_BITS); dev_dbg(&priv->spi->dev, "Effective speed %u, time per bit: %u, count bits: %u, count samples: %u\n", priv->effective_speed_hz, priv->time_per_bit_ns, bit_count, sample_count); return sample_count; } static u8 tsc2046_adc_get_cmd(struct tsc2046_adc_priv *priv, int ch_idx, bool keep_power) { u32 pd; /* * if PD bits are 0, controller will automatically disable ADC, VREF and * enable IRQ. */ if (keep_power) pd = TI_TSC2046_PD0_ADC_ON; else pd = 0; return TI_TSC2046_START | FIELD_PREP(TI_TSC2046_ADDR, ch_idx) | pd; } static u16 tsc2046_adc_get_value(struct tsc2046_adc_atom *buf) { return FIELD_GET(TI_TSC2046_DATA_12BIT, get_unaligned_be16(&buf->data)); } static int tsc2046_adc_read_one(struct tsc2046_adc_priv *priv, int ch_idx, u32 *effective_speed_hz) { struct spi_transfer xfer; struct spi_message msg; int ret; memset(&xfer, 0, sizeof(xfer)); priv->tx_one->cmd = tsc2046_adc_get_cmd(priv, ch_idx, false); priv->tx_one->data = 0; xfer.tx_buf = priv->tx_one; xfer.rx_buf = priv->rx_one; xfer.len = sizeof(*priv->tx_one); spi_message_init_with_transfers(&msg, &xfer, 1); /* * We aren't using spi_write_then_read() because we need to be able * to get hold of the effective_speed_hz from the xfer */ ret = spi_sync(priv->spi, &msg); if (ret) { dev_err_ratelimited(&priv->spi->dev, "SPI transfer failed %pe\n", ERR_PTR(ret)); return ret; } if (effective_speed_hz) *effective_speed_hz = xfer.effective_speed_hz; return tsc2046_adc_get_value(priv->rx_one); } static size_t tsc2046_adc_group_set_layout(struct tsc2046_adc_priv *priv, unsigned int group, unsigned int ch_idx) { struct tsc2046_adc_ch_cfg *ch = &priv->ch_cfg[ch_idx]; struct tsc2046_adc_group_layout *cur; unsigned int max_count, count_skip; unsigned int offset = 0; if (group) offset = priv->l[group - 1].offset + priv->l[group - 1].count; count_skip = tsc2046_adc_time_to_count(priv, ch->settling_time_us); max_count = count_skip + ch->oversampling_ratio; cur = &priv->l[group]; cur->offset = offset; cur->count = max_count; cur->skip = count_skip; return sizeof(*priv->tx) * max_count; } static void tsc2046_adc_group_set_cmd(struct tsc2046_adc_priv *priv, unsigned int group, int ch_idx) { struct tsc2046_adc_group_layout *l = &priv->l[group]; unsigned int i; u8 cmd; /* * Do not enable automatic power down on working samples. Otherwise the * plates will never be completely charged. */ cmd = tsc2046_adc_get_cmd(priv, ch_idx, true); for (i = 0; i < l->count - 1; i++) priv->tx[l->offset + i].cmd = cmd; /* automatically power down on last sample */ priv->tx[l->offset + i].cmd = tsc2046_adc_get_cmd(priv, ch_idx, false); } static u16 tsc2046_adc_get_val(struct tsc2046_adc_priv *priv, int group) { struct tsc2046_adc_group_layout *l; unsigned int val, val_normalized = 0; int valid_count, i; l = &priv->l[group]; valid_count = l->count - l->skip; for (i = 0; i < valid_count; i++) { val = tsc2046_adc_get_value(&priv->rx[l->offset + l->skip + i]); val_normalized += val; } return DIV_ROUND_UP(val_normalized, valid_count); } static int tsc2046_adc_scan(struct iio_dev *indio_dev) { struct tsc2046_adc_priv *priv = iio_priv(indio_dev); struct device *dev = &priv->spi->dev; int group; int ret; ret = spi_sync(priv->spi, &priv->msg); if (ret < 0) { dev_err_ratelimited(dev, "SPI transfer failed: %pe\n", ERR_PTR(ret)); return ret; } for (group = 0; group < priv->groups; group++) priv->scan_buf.data[group] = tsc2046_adc_get_val(priv, group); ret = iio_push_to_buffers_with_timestamp(indio_dev, &priv->scan_buf, iio_get_time_ns(indio_dev)); /* If the consumer is kfifo, we may get a EBUSY here - ignore it. */ if (ret < 0 && ret != -EBUSY) { dev_err_ratelimited(dev, "Failed to push scan buffer %pe\n", ERR_PTR(ret)); return ret; } return 0; } static irqreturn_t tsc2046_adc_trigger_handler(int irq, void *p) { struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct tsc2046_adc_priv *priv = iio_priv(indio_dev); mutex_lock(&priv->slock); tsc2046_adc_scan(indio_dev); mutex_unlock(&priv->slock); iio_trigger_notify_done(indio_dev->trig); return IRQ_HANDLED; } static int tsc2046_adc_update_scan_mode(struct iio_dev *indio_dev, const unsigned long *active_scan_mask) { struct tsc2046_adc_priv *priv = iio_priv(indio_dev); unsigned int ch_idx, group = 0; size_t size; mutex_lock(&priv->slock); size = 0; for_each_set_bit(ch_idx, active_scan_mask, indio_dev->num_channels) { size += tsc2046_adc_group_set_layout(priv, group, ch_idx); tsc2046_adc_group_set_cmd(priv, group, ch_idx); group++; } priv->groups = group; priv->xfer.len = size; priv->time_per_scan_us = size * 8 * priv->time_per_bit_ns / NSEC_PER_USEC; if (priv->scan_interval_us < priv->time_per_scan_us) dev_warn(&priv->spi->dev, "The scan interval (%d) is less then calculated scan time (%d)\n", priv->scan_interval_us, priv->time_per_scan_us); mutex_unlock(&priv->slock); return 0; } static const struct iio_info tsc2046_adc_info = { .update_scan_mode = tsc2046_adc_update_scan_mode, }; static enum hrtimer_restart tsc2046_adc_trig_more(struct hrtimer *hrtimer) { struct tsc2046_adc_priv *priv = container_of(hrtimer, struct tsc2046_adc_priv, trig_timer); unsigned long flags; spin_lock_irqsave(&priv->trig_lock, flags); disable_irq_nosync(priv->spi->irq); priv->trig_more_count++; iio_trigger_poll(priv->trig); spin_unlock_irqrestore(&priv->trig_lock, flags); return HRTIMER_NORESTART; } static irqreturn_t tsc2046_adc_irq(int irq, void *dev_id) { struct iio_dev *indio_dev = dev_id; struct tsc2046_adc_priv *priv = iio_priv(indio_dev); spin_lock(&priv->trig_lock); hrtimer_try_to_cancel(&priv->trig_timer); priv->trig_more_count = 0; disable_irq_nosync(priv->spi->irq); iio_trigger_poll(priv->trig); spin_unlock(&priv->trig_lock); return IRQ_HANDLED; } static void tsc2046_adc_reenable_trigger(struct iio_trigger *trig) { struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig); struct tsc2046_adc_priv *priv = iio_priv(indio_dev); unsigned long flags; int delta; /* * We can sample it as fast as we can, but usually we do not need so * many samples. Reduce the sample rate for default (touchscreen) use * case. * Currently we do not need a highly precise sample rate. It is enough * to have calculated numbers. */ delta = priv->scan_interval_us - priv->time_per_scan_us; if (delta > 0) fsleep(delta); spin_lock_irqsave(&priv->trig_lock, flags); /* * We need to trigger at least one extra sample to detect state * difference on ADC side. */ if (!priv->trig_more_count) { int timeout_ms = DIV_ROUND_UP(priv->scan_interval_us, USEC_PER_MSEC); hrtimer_start(&priv->trig_timer, ms_to_ktime(timeout_ms), HRTIMER_MODE_REL_SOFT); } enable_irq(priv->spi->irq); spin_unlock_irqrestore(&priv->trig_lock, flags); } static int tsc2046_adc_set_trigger_state(struct iio_trigger *trig, bool enable) { struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig); struct tsc2046_adc_priv *priv = iio_priv(indio_dev); if (enable) { enable_irq(priv->spi->irq); } else { disable_irq(priv->spi->irq); hrtimer_try_to_cancel(&priv->trig_timer); } return 0; } static const struct iio_trigger_ops tsc2046_adc_trigger_ops = { .set_trigger_state = tsc2046_adc_set_trigger_state, .reenable = tsc2046_adc_reenable_trigger, }; static int tsc2046_adc_setup_spi_msg(struct tsc2046_adc_priv *priv) { unsigned int ch_idx; size_t size; int ret; priv->tx_one = devm_kzalloc(&priv->spi->dev, sizeof(*priv->tx_one), GFP_KERNEL); if (!priv->tx_one) return -ENOMEM; priv->rx_one = devm_kzalloc(&priv->spi->dev, sizeof(*priv->rx_one), GFP_KERNEL); if (!priv->rx_one) return -ENOMEM; /* * Make dummy read to set initial power state and get real SPI clock * freq. It seems to be not important which channel is used for this * case. */ ret = tsc2046_adc_read_one(priv, TI_TSC2046_ADDR_TEMP0, &priv->effective_speed_hz); if (ret < 0) return ret; /* * In case SPI controller do not report effective_speed_hz, use * configure value and hope it will match. */ if (!priv->effective_speed_hz) priv->effective_speed_hz = priv->spi->max_speed_hz; priv->scan_interval_us = TI_TSC2046_SAMPLE_INTERVAL_US; priv->time_per_bit_ns = DIV_ROUND_UP(NSEC_PER_SEC, priv->effective_speed_hz); /* * Calculate and allocate maximal size buffer if all channels are * enabled. */ size = 0; for (ch_idx = 0; ch_idx < priv->dcfg->num_channels; ch_idx++) size += tsc2046_adc_group_set_layout(priv, ch_idx, ch_idx); priv->tx = devm_kzalloc(&priv->spi->dev, size, GFP_KERNEL); if (!priv->tx) return -ENOMEM; priv->rx = devm_kzalloc(&priv->spi->dev, size, GFP_KERNEL); if (!priv->rx) return -ENOMEM; priv->xfer.tx_buf = priv->tx; priv->xfer.rx_buf = priv->rx; priv->xfer.len = size; spi_message_init_with_transfers(&priv->msg, &priv->xfer, 1); return 0; } static void tsc2046_adc_parse_fwnode(struct tsc2046_adc_priv *priv) { struct fwnode_handle *child; struct device *dev = &priv->spi->dev; unsigned int i; for (i = 0; i < ARRAY_SIZE(priv->ch_cfg); i++) { priv->ch_cfg[i].settling_time_us = 1; priv->ch_cfg[i].oversampling_ratio = 1; } device_for_each_child_node(dev, child) { u32 stl, overs, reg; int ret; ret = fwnode_property_read_u32(child, "reg", ®); if (ret) { dev_err(dev, "invalid reg on %pfw, err: %pe\n", child, ERR_PTR(ret)); continue; } if (reg >= ARRAY_SIZE(priv->ch_cfg)) { dev_err(dev, "%pfw: Unsupported reg value: %i, max supported is: %zu.\n", child, reg, ARRAY_SIZE(priv->ch_cfg)); continue; } ret = fwnode_property_read_u32(child, "settling-time-us", &stl); if (!ret) priv->ch_cfg[reg].settling_time_us = stl; ret = fwnode_property_read_u32(child, "oversampling-ratio", &overs); if (!ret) priv->ch_cfg[reg].oversampling_ratio = overs; } } static int tsc2046_adc_probe(struct spi_device *spi) { const struct tsc2046_adc_dcfg *dcfg; struct device *dev = &spi->dev; struct tsc2046_adc_priv *priv; struct iio_dev *indio_dev; struct iio_trigger *trig; int ret; if (spi->max_speed_hz > TI_TSC2046_MAX_CLK_FREQ) { dev_err(dev, "SPI max_speed_hz is too high: %d Hz. Max supported freq is %zu Hz\n", spi->max_speed_hz, TI_TSC2046_MAX_CLK_FREQ); return -EINVAL; } dcfg = device_get_match_data(dev); if (!dcfg) return -EINVAL; spi->bits_per_word = 8; spi->mode &= ~SPI_MODE_X_MASK; spi->mode |= SPI_MODE_0; ret = spi_setup(spi); if (ret < 0) return dev_err_probe(dev, ret, "Error in SPI setup\n"); indio_dev = devm_iio_device_alloc(dev, sizeof(*priv)); if (!indio_dev) return -ENOMEM; priv = iio_priv(indio_dev); priv->dcfg = dcfg; priv->spi = spi; indio_dev->name = TI_TSC2046_NAME; indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_TRIGGERED; indio_dev->channels = dcfg->channels; indio_dev->num_channels = dcfg->num_channels; indio_dev->info = &tsc2046_adc_info; tsc2046_adc_parse_fwnode(priv); ret = tsc2046_adc_setup_spi_msg(priv); if (ret) return ret; mutex_init(&priv->slock); ret = devm_request_irq(dev, spi->irq, &tsc2046_adc_irq, IRQF_NO_AUTOEN, indio_dev->name, indio_dev); if (ret) return ret; trig = devm_iio_trigger_alloc(dev, "touchscreen-%s", indio_dev->name); if (!trig) return -ENOMEM; priv->trig = trig; iio_trigger_set_drvdata(trig, indio_dev); trig->ops = &tsc2046_adc_trigger_ops; spin_lock_init(&priv->trig_lock); hrtimer_init(&priv->trig_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT); priv->trig_timer.function = tsc2046_adc_trig_more; ret = devm_iio_trigger_register(dev, trig); if (ret) { dev_err(dev, "failed to register trigger\n"); return ret; } ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL, &tsc2046_adc_trigger_handler, NULL); if (ret) { dev_err(dev, "Failed to setup triggered buffer\n"); return ret; } /* set default trigger */ indio_dev->trig = iio_trigger_get(priv->trig); return devm_iio_device_register(dev, indio_dev); } static const struct of_device_id ads7950_of_table[] = { { .compatible = "ti,tsc2046e-adc", .data = &tsc2046_adc_dcfg_tsc2046e }, { } }; MODULE_DEVICE_TABLE(of, ads7950_of_table); static struct spi_driver tsc2046_adc_driver = { .driver = { .name = "tsc2046", .of_match_table = ads7950_of_table, }, .probe = tsc2046_adc_probe, }; module_spi_driver(tsc2046_adc_driver); MODULE_AUTHOR("Oleksij Rempel "); MODULE_DESCRIPTION("TI TSC2046 ADC"); MODULE_LICENSE("GPL v2");