diff options
Diffstat (limited to 'drivers/input/touchscreen/ads7846.c')
| -rw-r--r-- | drivers/input/touchscreen/ads7846.c | 1401 |
1 files changed, 1401 insertions, 0 deletions
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c new file mode 100644 index 0000000000..faea40dd66 --- /dev/null +++ b/drivers/input/touchscreen/ads7846.c @@ -0,0 +1,1401 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * ADS7846 based touchscreen and sensor driver + * + * Copyright (c) 2005 David Brownell + * Copyright (c) 2006 Nokia Corporation + * Various changes: Imre Deak <imre.deak@nokia.com> + * + * Using code from: + * - corgi_ts.c + * Copyright (C) 2004-2005 Richard Purdie + * - omap_ts.[hc], ads7846.h, ts_osk.c + * Copyright (C) 2002 MontaVista Software + * Copyright (C) 2004 Texas Instruments + * Copyright (C) 2005 Dirk Behme + */ +#include <linux/types.h> +#include <linux/hwmon.h> +#include <linux/err.h> +#include <linux/sched.h> +#include <linux/delay.h> +#include <linux/input.h> +#include <linux/input/touchscreen.h> +#include <linux/interrupt.h> +#include <linux/slab.h> +#include <linux/pm.h> +#include <linux/property.h> +#include <linux/gpio/consumer.h> +#include <linux/spi/spi.h> +#include <linux/spi/ads7846.h> +#include <linux/regulator/consumer.h> +#include <linux/module.h> +#include <asm/unaligned.h> + +/* + * This code has been heavily tested on a Nokia 770, and lightly + * tested on other ads7846 devices (OSK/Mistral, Lubbock, Spitz). + * TSC2046 is just newer ads7846 silicon. + * Support for ads7843 tested on Atmel at91sam926x-EK. + * Support for ads7845 has only been stubbed in. + * Support for Analog Devices AD7873 and AD7843 tested. + * + * IRQ handling needs a workaround because of a shortcoming in handling + * edge triggered IRQs on some platforms like the OMAP1/2. These + * platforms don't handle the ARM lazy IRQ disabling properly, thus we + * have to maintain our own SW IRQ disabled status. This should be + * removed as soon as the affected platform's IRQ handling is fixed. + * + * App note sbaa036 talks in more detail about accurate sampling... + * that ought to help in situations like LCDs inducing noise (which + * can also be helped by using synch signals) and more generally. + * This driver tries to utilize the measures described in the app + * note. The strength of filtering can be set in the board-* specific + * files. + */ + +#define TS_POLL_DELAY 1 /* ms delay before the first sample */ +#define TS_POLL_PERIOD 5 /* ms delay between samples */ + +/* this driver doesn't aim at the peak continuous sample rate */ +#define SAMPLE_BITS (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */) + +struct ads7846_buf { + u8 cmd; + __be16 data; +} __packed; + +struct ads7846_buf_layout { + unsigned int offset; + unsigned int count; + unsigned int skip; +}; + +/* + * We allocate this separately to avoid cache line sharing issues when + * driver is used with DMA-based SPI controllers (like atmel_spi) on + * systems where main memory is not DMA-coherent (most non-x86 boards). + */ +struct ads7846_packet { + unsigned int count; + unsigned int count_skip; + unsigned int cmds; + unsigned int last_cmd_idx; + struct ads7846_buf_layout l[5]; + struct ads7846_buf *rx; + struct ads7846_buf *tx; + + struct ads7846_buf pwrdown_cmd; + + bool ignore; + u16 x, y, z1, z2; +}; + +struct ads7846 { + struct input_dev *input; + char phys[32]; + char name[32]; + + struct spi_device *spi; + struct regulator *reg; + + u16 model; + u16 vref_mv; + u16 vref_delay_usecs; + u16 x_plate_ohms; + u16 pressure_max; + + bool swap_xy; + bool use_internal; + + struct ads7846_packet *packet; + + struct spi_transfer xfer[18]; + struct spi_message msg[5]; + int msg_count; + wait_queue_head_t wait; + + bool pendown; + + int read_cnt; + int read_rep; + int last_read; + + u16 debounce_max; + u16 debounce_tol; + u16 debounce_rep; + + u16 penirq_recheck_delay_usecs; + + struct touchscreen_properties core_prop; + + struct mutex lock; + bool stopped; /* P: lock */ + bool disabled; /* P: lock */ + bool suspended; /* P: lock */ + + int (*filter)(void *data, int data_idx, int *val); + void *filter_data; + int (*get_pendown_state)(void); + struct gpio_desc *gpio_pendown; + + void (*wait_for_sync)(void); +}; + +enum ads7846_filter { + ADS7846_FILTER_OK, + ADS7846_FILTER_REPEAT, + ADS7846_FILTER_IGNORE, +}; + +/* leave chip selected when we're done, for quicker re-select? */ +#if 0 +#define CS_CHANGE(xfer) ((xfer).cs_change = 1) +#else +#define CS_CHANGE(xfer) ((xfer).cs_change = 0) +#endif + +/*--------------------------------------------------------------------------*/ + +/* The ADS7846 has touchscreen and other sensors. + * Earlier ads784x chips are somewhat compatible. + */ +#define ADS_START (1 << 7) +#define ADS_A2A1A0_d_y (1 << 4) /* differential */ +#define ADS_A2A1A0_d_z1 (3 << 4) /* differential */ +#define ADS_A2A1A0_d_z2 (4 << 4) /* differential */ +#define ADS_A2A1A0_d_x (5 << 4) /* differential */ +#define ADS_A2A1A0_temp0 (0 << 4) /* non-differential */ +#define ADS_A2A1A0_vbatt (2 << 4) /* non-differential */ +#define ADS_A2A1A0_vaux (6 << 4) /* non-differential */ +#define ADS_A2A1A0_temp1 (7 << 4) /* non-differential */ +#define ADS_8_BIT (1 << 3) +#define ADS_12_BIT (0 << 3) +#define ADS_SER (1 << 2) /* non-differential */ +#define ADS_DFR (0 << 2) /* differential */ +#define ADS_PD10_PDOWN (0 << 0) /* low power mode + penirq */ +#define ADS_PD10_ADC_ON (1 << 0) /* ADC on */ +#define ADS_PD10_REF_ON (2 << 0) /* vREF on + penirq */ +#define ADS_PD10_ALL_ON (3 << 0) /* ADC + vREF on */ + +#define MAX_12BIT ((1<<12)-1) + +/* leave ADC powered up (disables penirq) between differential samples */ +#define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \ + | ADS_12_BIT | ADS_DFR | \ + (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0)) + +#define READ_Y(vref) (READ_12BIT_DFR(y, 1, vref)) +#define READ_Z1(vref) (READ_12BIT_DFR(z1, 1, vref)) +#define READ_Z2(vref) (READ_12BIT_DFR(z2, 1, vref)) +#define READ_X(vref) (READ_12BIT_DFR(x, 1, vref)) +#define PWRDOWN (READ_12BIT_DFR(y, 0, 0)) /* LAST */ + +/* single-ended samples need to first power up reference voltage; + * we leave both ADC and VREF powered + */ +#define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \ + | ADS_12_BIT | ADS_SER) + +#define REF_ON (READ_12BIT_DFR(x, 1, 1)) +#define REF_OFF (READ_12BIT_DFR(y, 0, 0)) + +/* Order commands in the most optimal way to reduce Vref switching and + * settling time: + * Measure: X; Vref: X+, X-; IN: Y+ + * Measure: Y; Vref: Y+, Y-; IN: X+ + * Measure: Z1; Vref: Y+, X-; IN: X+ + * Measure: Z2; Vref: Y+, X-; IN: Y- + */ +enum ads7846_cmds { + ADS7846_X, + ADS7846_Y, + ADS7846_Z1, + ADS7846_Z2, + ADS7846_PWDOWN, +}; + +static int get_pendown_state(struct ads7846 *ts) +{ + if (ts->get_pendown_state) + return ts->get_pendown_state(); + + return gpiod_get_value(ts->gpio_pendown); +} + +static void ads7846_report_pen_up(struct ads7846 *ts) +{ + struct input_dev *input = ts->input; + + input_report_key(input, BTN_TOUCH, 0); + input_report_abs(input, ABS_PRESSURE, 0); + input_sync(input); + + ts->pendown = false; + dev_vdbg(&ts->spi->dev, "UP\n"); +} + +/* Must be called with ts->lock held */ +static void ads7846_stop(struct ads7846 *ts) +{ + if (!ts->disabled && !ts->suspended) { + /* Signal IRQ thread to stop polling and disable the handler. */ + ts->stopped = true; + mb(); + wake_up(&ts->wait); + disable_irq(ts->spi->irq); + } +} + +/* Must be called with ts->lock held */ +static void ads7846_restart(struct ads7846 *ts) +{ + if (!ts->disabled && !ts->suspended) { + /* Check if pen was released since last stop */ + if (ts->pendown && !get_pendown_state(ts)) + ads7846_report_pen_up(ts); + + /* Tell IRQ thread that it may poll the device. */ + ts->stopped = false; + mb(); + enable_irq(ts->spi->irq); + } +} + +/* Must be called with ts->lock held */ +static void __ads7846_disable(struct ads7846 *ts) +{ + ads7846_stop(ts); + regulator_disable(ts->reg); + + /* + * We know the chip's in low power mode since we always + * leave it that way after every request + */ +} + +/* Must be called with ts->lock held */ +static void __ads7846_enable(struct ads7846 *ts) +{ + int error; + + error = regulator_enable(ts->reg); + if (error != 0) + dev_err(&ts->spi->dev, "Failed to enable supply: %d\n", error); + + ads7846_restart(ts); +} + +static void ads7846_disable(struct ads7846 *ts) +{ + mutex_lock(&ts->lock); + + if (!ts->disabled) { + + if (!ts->suspended) + __ads7846_disable(ts); + + ts->disabled = true; + } + + mutex_unlock(&ts->lock); +} + +static void ads7846_enable(struct ads7846 *ts) +{ + mutex_lock(&ts->lock); + + if (ts->disabled) { + + ts->disabled = false; + + if (!ts->suspended) + __ads7846_enable(ts); + } + + mutex_unlock(&ts->lock); +} + +/*--------------------------------------------------------------------------*/ + +/* + * Non-touchscreen sensors only use single-ended conversions. + * The range is GND..vREF. The ads7843 and ads7835 must use external vREF; + * ads7846 lets that pin be unconnected, to use internal vREF. + */ + +struct ser_req { + u8 ref_on; + u8 command; + u8 ref_off; + u16 scratch; + struct spi_message msg; + struct spi_transfer xfer[6]; + /* + * DMA (thus cache coherency maintenance) requires the + * transfer buffers to live in their own cache lines. + */ + __be16 sample ____cacheline_aligned; +}; + +struct ads7845_ser_req { + u8 command[3]; + struct spi_message msg; + struct spi_transfer xfer[2]; + /* + * DMA (thus cache coherency maintenance) requires the + * transfer buffers to live in their own cache lines. + */ + u8 sample[3] ____cacheline_aligned; +}; + +static int ads7846_read12_ser(struct device *dev, unsigned command) +{ + struct spi_device *spi = to_spi_device(dev); + struct ads7846 *ts = dev_get_drvdata(dev); + struct ser_req *req; + int status; + + req = kzalloc(sizeof *req, GFP_KERNEL); + if (!req) + return -ENOMEM; + + spi_message_init(&req->msg); + + /* maybe turn on internal vREF, and let it settle */ + if (ts->use_internal) { + req->ref_on = REF_ON; + req->xfer[0].tx_buf = &req->ref_on; + req->xfer[0].len = 1; + spi_message_add_tail(&req->xfer[0], &req->msg); + + req->xfer[1].rx_buf = &req->scratch; + req->xfer[1].len = 2; + + /* for 1uF, settle for 800 usec; no cap, 100 usec. */ + req->xfer[1].delay.value = ts->vref_delay_usecs; + req->xfer[1].delay.unit = SPI_DELAY_UNIT_USECS; + spi_message_add_tail(&req->xfer[1], &req->msg); + + /* Enable reference voltage */ + command |= ADS_PD10_REF_ON; + } + + /* Enable ADC in every case */ + command |= ADS_PD10_ADC_ON; + + /* take sample */ + req->command = (u8) command; + req->xfer[2].tx_buf = &req->command; + req->xfer[2].len = 1; + spi_message_add_tail(&req->xfer[2], &req->msg); + + req->xfer[3].rx_buf = &req->sample; + req->xfer[3].len = 2; + spi_message_add_tail(&req->xfer[3], &req->msg); + + /* REVISIT: take a few more samples, and compare ... */ + + /* converter in low power mode & enable PENIRQ */ + req->ref_off = PWRDOWN; + req->xfer[4].tx_buf = &req->ref_off; + req->xfer[4].len = 1; + spi_message_add_tail(&req->xfer[4], &req->msg); + + req->xfer[5].rx_buf = &req->scratch; + req->xfer[5].len = 2; + CS_CHANGE(req->xfer[5]); + spi_message_add_tail(&req->xfer[5], &req->msg); + + mutex_lock(&ts->lock); + ads7846_stop(ts); + status = spi_sync(spi, &req->msg); + ads7846_restart(ts); + mutex_unlock(&ts->lock); + + if (status == 0) { + /* on-wire is a must-ignore bit, a BE12 value, then padding */ + status = be16_to_cpu(req->sample); + status = status >> 3; + status &= 0x0fff; + } + + kfree(req); + return status; +} + +static int ads7845_read12_ser(struct device *dev, unsigned command) +{ + struct spi_device *spi = to_spi_device(dev); + struct ads7846 *ts = dev_get_drvdata(dev); + struct ads7845_ser_req *req; + int status; + + req = kzalloc(sizeof *req, GFP_KERNEL); + if (!req) + return -ENOMEM; + + spi_message_init(&req->msg); + + req->command[0] = (u8) command; + req->xfer[0].tx_buf = req->command; + req->xfer[0].rx_buf = req->sample; + req->xfer[0].len = 3; + spi_message_add_tail(&req->xfer[0], &req->msg); + + mutex_lock(&ts->lock); + ads7846_stop(ts); + status = spi_sync(spi, &req->msg); + ads7846_restart(ts); + mutex_unlock(&ts->lock); + + if (status == 0) { + /* BE12 value, then padding */ + status = get_unaligned_be16(&req->sample[1]); + status = status >> 3; + status &= 0x0fff; + } + + kfree(req); + return status; +} + +#if IS_ENABLED(CONFIG_HWMON) + +#define SHOW(name, var, adjust) static ssize_t \ +name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \ +{ \ + struct ads7846 *ts = dev_get_drvdata(dev); \ + ssize_t v = ads7846_read12_ser(&ts->spi->dev, \ + READ_12BIT_SER(var)); \ + if (v < 0) \ + return v; \ + return sprintf(buf, "%u\n", adjust(ts, v)); \ +} \ +static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL); + + +/* Sysfs conventions report temperatures in millidegrees Celsius. + * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high + * accuracy scheme without calibration data. For now we won't try either; + * userspace sees raw sensor values, and must scale/calibrate appropriately. + */ +static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v) +{ + return v; +} + +SHOW(temp0, temp0, null_adjust) /* temp1_input */ +SHOW(temp1, temp1, null_adjust) /* temp2_input */ + + +/* sysfs conventions report voltages in millivolts. We can convert voltages + * if we know vREF. userspace may need to scale vAUX to match the board's + * external resistors; we assume that vBATT only uses the internal ones. + */ +static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v) +{ + unsigned retval = v; + + /* external resistors may scale vAUX into 0..vREF */ + retval *= ts->vref_mv; + retval = retval >> 12; + + return retval; +} + +static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v) +{ + unsigned retval = vaux_adjust(ts, v); + + /* ads7846 has a resistor ladder to scale this signal down */ + if (ts->model == 7846) + retval *= 4; + + return retval; +} + +SHOW(in0_input, vaux, vaux_adjust) +SHOW(in1_input, vbatt, vbatt_adjust) + +static umode_t ads7846_is_visible(struct kobject *kobj, struct attribute *attr, + int index) +{ + struct device *dev = kobj_to_dev(kobj); + struct ads7846 *ts = dev_get_drvdata(dev); + + if (ts->model == 7843 && index < 2) /* in0, in1 */ + return 0; + if (ts->model == 7845 && index != 2) /* in0 */ + return 0; + + return attr->mode; +} + +static struct attribute *ads7846_attributes[] = { + &dev_attr_temp0.attr, /* 0 */ + &dev_attr_temp1.attr, /* 1 */ + &dev_attr_in0_input.attr, /* 2 */ + &dev_attr_in1_input.attr, /* 3 */ + NULL, +}; + +static const struct attribute_group ads7846_attr_group = { + .attrs = ads7846_attributes, + .is_visible = ads7846_is_visible, +}; +__ATTRIBUTE_GROUPS(ads7846_attr); + +static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts) +{ + struct device *hwmon; + + /* hwmon sensors need a reference voltage */ + switch (ts->model) { + case 7846: + if (!ts->vref_mv) { + dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n"); + ts->vref_mv = 2500; + ts->use_internal = true; + } + break; + case 7845: + case 7843: + if (!ts->vref_mv) { + dev_warn(&spi->dev, + "external vREF for ADS%d not specified\n", + ts->model); + return 0; + } + break; + } + + hwmon = devm_hwmon_device_register_with_groups(&spi->dev, + spi->modalias, ts, + ads7846_attr_groups); + + return PTR_ERR_OR_ZERO(hwmon); +} + +#else +static inline int ads784x_hwmon_register(struct spi_device *spi, + struct ads7846 *ts) +{ + return 0; +} +#endif + +static ssize_t ads7846_pen_down_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct ads7846 *ts = dev_get_drvdata(dev); + + return sprintf(buf, "%u\n", ts->pendown); +} + +static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL); + +static ssize_t ads7846_disable_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct ads7846 *ts = dev_get_drvdata(dev); + + return sprintf(buf, "%u\n", ts->disabled); +} + +static ssize_t ads7846_disable_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct ads7846 *ts = dev_get_drvdata(dev); + unsigned int i; + int err; + + err = kstrtouint(buf, 10, &i); + if (err) + return err; + + if (i) + ads7846_disable(ts); + else + ads7846_enable(ts); + + return count; +} + +static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store); + +static struct attribute *ads784x_attributes[] = { + &dev_attr_pen_down.attr, + &dev_attr_disable.attr, + NULL, +}; + +static const struct attribute_group ads784x_attr_group = { + .attrs = ads784x_attributes, +}; + +/*--------------------------------------------------------------------------*/ + +static void null_wait_for_sync(void) +{ +} + +static int ads7846_debounce_filter(void *ads, int data_idx, int *val) +{ + struct ads7846 *ts = ads; + + if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) { + /* Start over collecting consistent readings. */ + ts->read_rep = 0; + /* + * Repeat it, if this was the first read or the read + * wasn't consistent enough. + */ + if (ts->read_cnt < ts->debounce_max) { + ts->last_read = *val; + ts->read_cnt++; + return ADS7846_FILTER_REPEAT; + } else { + /* + * Maximum number of debouncing reached and still + * not enough number of consistent readings. Abort + * the whole sample, repeat it in the next sampling + * period. + */ + ts->read_cnt = 0; + return ADS7846_FILTER_IGNORE; + } + } else { + if (++ts->read_rep > ts->debounce_rep) { + /* + * Got a good reading for this coordinate, + * go for the next one. + */ + ts->read_cnt = 0; + ts->read_rep = 0; + return ADS7846_FILTER_OK; + } else { + /* Read more values that are consistent. */ + ts->read_cnt++; + return ADS7846_FILTER_REPEAT; + } + } +} + +static int ads7846_no_filter(void *ads, int data_idx, int *val) +{ + return ADS7846_FILTER_OK; +} + +static int ads7846_get_value(struct ads7846_buf *buf) +{ + int value; + + value = be16_to_cpup(&buf->data); + + /* enforce ADC output is 12 bits width */ + return (value >> 3) & 0xfff; +} + +static void ads7846_set_cmd_val(struct ads7846 *ts, enum ads7846_cmds cmd_idx, + u16 val) +{ + struct ads7846_packet *packet = ts->packet; + + switch (cmd_idx) { + case ADS7846_Y: + packet->y = val; + break; + case ADS7846_X: + packet->x = val; + break; + case ADS7846_Z1: + packet->z1 = val; + break; + case ADS7846_Z2: + packet->z2 = val; + break; + default: + WARN_ON_ONCE(1); + } +} + +static u8 ads7846_get_cmd(enum ads7846_cmds cmd_idx, int vref) +{ + switch (cmd_idx) { + case ADS7846_Y: + return READ_Y(vref); + case ADS7846_X: + return READ_X(vref); + + /* 7846 specific commands */ + case ADS7846_Z1: + return READ_Z1(vref); + case ADS7846_Z2: + return READ_Z2(vref); + case ADS7846_PWDOWN: + return PWRDOWN; + default: + WARN_ON_ONCE(1); + } + + return 0; +} + +static bool ads7846_cmd_need_settle(enum ads7846_cmds cmd_idx) +{ + switch (cmd_idx) { + case ADS7846_X: + case ADS7846_Y: + case ADS7846_Z1: + case ADS7846_Z2: + return true; + case ADS7846_PWDOWN: + return false; + default: + WARN_ON_ONCE(1); + } + + return false; +} + +static int ads7846_filter(struct ads7846 *ts) +{ + struct ads7846_packet *packet = ts->packet; + int action; + int val; + unsigned int cmd_idx, b; + + packet->ignore = false; + for (cmd_idx = packet->last_cmd_idx; cmd_idx < packet->cmds - 1; cmd_idx++) { + struct ads7846_buf_layout *l = &packet->l[cmd_idx]; + + packet->last_cmd_idx = cmd_idx; + + for (b = l->skip; b < l->count; b++) { + val = ads7846_get_value(&packet->rx[l->offset + b]); + + action = ts->filter(ts->filter_data, cmd_idx, &val); + if (action == ADS7846_FILTER_REPEAT) { + if (b == l->count - 1) + return -EAGAIN; + } else if (action == ADS7846_FILTER_OK) { + ads7846_set_cmd_val(ts, cmd_idx, val); + break; + } else { + packet->ignore = true; + return 0; + } + } + } + + return 0; +} + +static void ads7846_read_state(struct ads7846 *ts) +{ + struct ads7846_packet *packet = ts->packet; + struct spi_message *m; + int msg_idx = 0; + int error; + + packet->last_cmd_idx = 0; + + while (true) { + ts->wait_for_sync(); + + m = &ts->msg[msg_idx]; + error = spi_sync(ts->spi, m); + if (error) { + dev_err(&ts->spi->dev, "spi_sync --> %d\n", error); + packet->ignore = true; + return; + } + + error = ads7846_filter(ts); + if (error) + continue; + + return; + } +} + +static void ads7846_report_state(struct ads7846 *ts) +{ + struct ads7846_packet *packet = ts->packet; + unsigned int Rt; + u16 x, y, z1, z2; + + x = packet->x; + y = packet->y; + if (ts->model == 7845) { + z1 = 0; + z2 = 0; + } else { + z1 = packet->z1; + z2 = packet->z2; + } + + /* range filtering */ + if (x == MAX_12BIT) + x = 0; + + if (ts->model == 7843 || ts->model == 7845) { + Rt = ts->pressure_max / 2; + } else if (likely(x && z1)) { + /* compute touch pressure resistance using equation #2 */ + Rt = z2; + Rt -= z1; + Rt *= ts->x_plate_ohms; + Rt = DIV_ROUND_CLOSEST(Rt, 16); + Rt *= x; + Rt /= z1; + Rt = DIV_ROUND_CLOSEST(Rt, 256); + } else { + Rt = 0; + } + + /* + * Sample found inconsistent by debouncing or pressure is beyond + * the maximum. Don't report it to user space, repeat at least + * once more the measurement + */ + if (packet->ignore || Rt > ts->pressure_max) { + dev_vdbg(&ts->spi->dev, "ignored %d pressure %d\n", + packet->ignore, Rt); + return; + } + + /* + * Maybe check the pendown state before reporting. This discards + * false readings when the pen is lifted. + */ + if (ts->penirq_recheck_delay_usecs) { + udelay(ts->penirq_recheck_delay_usecs); + if (!get_pendown_state(ts)) + Rt = 0; + } + + /* + * NOTE: We can't rely on the pressure to determine the pen down + * state, even this controller has a pressure sensor. The pressure + * value can fluctuate for quite a while after lifting the pen and + * in some cases may not even settle at the expected value. + * + * The only safe way to check for the pen up condition is in the + * timer by reading the pen signal state (it's a GPIO _and_ IRQ). + */ + if (Rt) { + struct input_dev *input = ts->input; + + if (!ts->pendown) { + input_report_key(input, BTN_TOUCH, 1); + ts->pendown = true; + dev_vdbg(&ts->spi->dev, "DOWN\n"); + } + + touchscreen_report_pos(input, &ts->core_prop, x, y, false); + input_report_abs(input, ABS_PRESSURE, ts->pressure_max - Rt); + + input_sync(input); + dev_vdbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt); + } +} + +static irqreturn_t ads7846_hard_irq(int irq, void *handle) +{ + struct ads7846 *ts = handle; + + return get_pendown_state(ts) ? IRQ_WAKE_THREAD : IRQ_HANDLED; +} + + +static irqreturn_t ads7846_irq(int irq, void *handle) +{ + struct ads7846 *ts = handle; + + /* Start with a small delay before checking pendown state */ + msleep(TS_POLL_DELAY); + + while (!ts->stopped && get_pendown_state(ts)) { + + /* pen is down, continue with the measurement */ + ads7846_read_state(ts); + + if (!ts->stopped) + ads7846_report_state(ts); + + wait_event_timeout(ts->wait, ts->stopped, + msecs_to_jiffies(TS_POLL_PERIOD)); + } + + if (ts->pendown && !ts->stopped) + ads7846_report_pen_up(ts); + + return IRQ_HANDLED; +} + +static int ads7846_suspend(struct device *dev) +{ + struct ads7846 *ts = dev_get_drvdata(dev); + + mutex_lock(&ts->lock); + + if (!ts->suspended) { + + if (!ts->disabled) + __ads7846_disable(ts); + + if (device_may_wakeup(&ts->spi->dev)) + enable_irq_wake(ts->spi->irq); + + ts->suspended = true; + } + + mutex_unlock(&ts->lock); + + return 0; +} + +static int ads7846_resume(struct device *dev) +{ + struct ads7846 *ts = dev_get_drvdata(dev); + + mutex_lock(&ts->lock); + + if (ts->suspended) { + + ts->suspended = false; + + if (device_may_wakeup(&ts->spi->dev)) + disable_irq_wake(ts->spi->irq); + + if (!ts->disabled) + __ads7846_enable(ts); + } + + mutex_unlock(&ts->lock); + + return 0; +} + +static DEFINE_SIMPLE_DEV_PM_OPS(ads7846_pm, ads7846_suspend, ads7846_resume); + +static int ads7846_setup_pendown(struct spi_device *spi, + struct ads7846 *ts, + const struct ads7846_platform_data *pdata) +{ + /* + * REVISIT when the irq can be triggered active-low, or if for some + * reason the touchscreen isn't hooked up, we don't need to access + * the pendown state. + */ + + if (pdata->get_pendown_state) { + ts->get_pendown_state = pdata->get_pendown_state; + } else { + ts->gpio_pendown = gpiod_get(&spi->dev, "pendown", GPIOD_IN); + if (IS_ERR(ts->gpio_pendown)) { + dev_err(&spi->dev, "failed to request pendown GPIO\n"); + return PTR_ERR(ts->gpio_pendown); + } + if (pdata->gpio_pendown_debounce) + gpiod_set_debounce(ts->gpio_pendown, + pdata->gpio_pendown_debounce); + } + + return 0; +} + +/* + * Set up the transfers to read touchscreen state; this assumes we + * use formula #2 for pressure, not #3. + */ +static int ads7846_setup_spi_msg(struct ads7846 *ts, + const struct ads7846_platform_data *pdata) +{ + struct spi_message *m = &ts->msg[0]; + struct spi_transfer *x = ts->xfer; + struct ads7846_packet *packet = ts->packet; + int vref = pdata->keep_vref_on; + unsigned int count, offset = 0; + unsigned int cmd_idx, b; + unsigned long time; + size_t size = 0; + + /* time per bit */ + time = NSEC_PER_SEC / ts->spi->max_speed_hz; + + count = pdata->settle_delay_usecs * NSEC_PER_USEC / time; + packet->count_skip = DIV_ROUND_UP(count, 24); + + if (ts->debounce_max && ts->debounce_rep) + /* ads7846_debounce_filter() is making ts->debounce_rep + 2 + * reads. So we need to get all samples for normal case. */ + packet->count = ts->debounce_rep + 2; + else + packet->count = 1; + + if (ts->model == 7846) + packet->cmds = 5; /* x, y, z1, z2, pwdown */ + else + packet->cmds = 3; /* x, y, pwdown */ + + for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) { + struct ads7846_buf_layout *l = &packet->l[cmd_idx]; + unsigned int max_count; + + if (cmd_idx == packet->cmds - 1) + cmd_idx = ADS7846_PWDOWN; + + if (ads7846_cmd_need_settle(cmd_idx)) + max_count = packet->count + packet->count_skip; + else + max_count = packet->count; + + l->offset = offset; + offset += max_count; + l->count = max_count; + l->skip = packet->count_skip; + size += sizeof(*packet->tx) * max_count; + } + + packet->tx = devm_kzalloc(&ts->spi->dev, size, GFP_KERNEL); + if (!packet->tx) + return -ENOMEM; + + packet->rx = devm_kzalloc(&ts->spi->dev, size, GFP_KERNEL); + if (!packet->rx) + return -ENOMEM; + + if (ts->model == 7873) { + /* + * The AD7873 is almost identical to the ADS7846 + * keep VREF off during differential/ratiometric + * conversion modes. + */ + ts->model = 7846; + vref = 0; + } + + ts->msg_count = 1; + spi_message_init(m); + m->context = ts; + + for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) { + struct ads7846_buf_layout *l = &packet->l[cmd_idx]; + u8 cmd; + + if (cmd_idx == packet->cmds - 1) + cmd_idx = ADS7846_PWDOWN; + + cmd = ads7846_get_cmd(cmd_idx, vref); + + for (b = 0; b < l->count; b++) + packet->tx[l->offset + b].cmd = cmd; + } + + x->tx_buf = packet->tx; + x->rx_buf = packet->rx; + x->len = size; + spi_message_add_tail(x, m); + + return 0; +} + +static const struct of_device_id ads7846_dt_ids[] = { + { .compatible = "ti,tsc2046", .data = (void *) 7846 }, + { .compatible = "ti,ads7843", .data = (void *) 7843 }, + { .compatible = "ti,ads7845", .data = (void *) 7845 }, + { .compatible = "ti,ads7846", .data = (void *) 7846 }, + { .compatible = "ti,ads7873", .data = (void *) 7873 }, + { } +}; +MODULE_DEVICE_TABLE(of, ads7846_dt_ids); + +static const struct ads7846_platform_data *ads7846_get_props(struct device *dev) +{ + struct ads7846_platform_data *pdata; + u32 value; + + pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL); + if (!pdata) + return ERR_PTR(-ENOMEM); + + pdata->model = (uintptr_t)device_get_match_data(dev); + + device_property_read_u16(dev, "ti,vref-delay-usecs", + &pdata->vref_delay_usecs); + device_property_read_u16(dev, "ti,vref-mv", &pdata->vref_mv); + pdata->keep_vref_on = device_property_read_bool(dev, "ti,keep-vref-on"); + + pdata->swap_xy = device_property_read_bool(dev, "ti,swap-xy"); + + device_property_read_u16(dev, "ti,settle-delay-usec", + &pdata->settle_delay_usecs); + device_property_read_u16(dev, "ti,penirq-recheck-delay-usecs", + &pdata->penirq_recheck_delay_usecs); + + device_property_read_u16(dev, "ti,x-plate-ohms", &pdata->x_plate_ohms); + device_property_read_u16(dev, "ti,y-plate-ohms", &pdata->y_plate_ohms); + + device_property_read_u16(dev, "ti,x-min", &pdata->x_min); + device_property_read_u16(dev, "ti,y-min", &pdata->y_min); + device_property_read_u16(dev, "ti,x-max", &pdata->x_max); + device_property_read_u16(dev, "ti,y-max", &pdata->y_max); + + /* + * touchscreen-max-pressure gets parsed during + * touchscreen_parse_properties() + */ + device_property_read_u16(dev, "ti,pressure-min", &pdata->pressure_min); + if (!device_property_read_u32(dev, "touchscreen-min-pressure", &value)) + pdata->pressure_min = (u16) value; + device_property_read_u16(dev, "ti,pressure-max", &pdata->pressure_max); + + device_property_read_u16(dev, "ti,debounce-max", &pdata->debounce_max); + if (!device_property_read_u32(dev, "touchscreen-average-samples", &value)) + pdata->debounce_max = (u16) value; + device_property_read_u16(dev, "ti,debounce-tol", &pdata->debounce_tol); + device_property_read_u16(dev, "ti,debounce-rep", &pdata->debounce_rep); + + device_property_read_u32(dev, "ti,pendown-gpio-debounce", + &pdata->gpio_pendown_debounce); + + pdata->wakeup = device_property_read_bool(dev, "wakeup-source") || + device_property_read_bool(dev, "linux,wakeup"); + + return pdata; +} + +static void ads7846_regulator_disable(void *regulator) +{ + regulator_disable(regulator); +} + +static int ads7846_probe(struct spi_device *spi) +{ + const struct ads7846_platform_data *pdata; + struct ads7846 *ts; + struct device *dev = &spi->dev; + struct ads7846_packet *packet; + struct input_dev *input_dev; + unsigned long irq_flags; + int err; + + if (!spi->irq) { + dev_dbg(dev, "no IRQ?\n"); + return -EINVAL; + } + + /* don't exceed max specified sample rate */ + if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) { + dev_err(dev, "f(sample) %d KHz?\n", + (spi->max_speed_hz/SAMPLE_BITS)/1000); + return -EINVAL; + } + + /* + * We'd set TX word size 8 bits and RX word size to 13 bits ... except + * that even if the hardware can do that, the SPI controller driver + * may not. So we stick to very-portable 8 bit words, both RX and TX. + */ + spi->bits_per_word = 8; + spi->mode &= ~SPI_MODE_X_MASK; + spi->mode |= SPI_MODE_0; + err = spi_setup(spi); + if (err < 0) + return err; + + ts = devm_kzalloc(dev, sizeof(struct ads7846), GFP_KERNEL); + if (!ts) + return -ENOMEM; + + packet = devm_kzalloc(dev, sizeof(struct ads7846_packet), GFP_KERNEL); + if (!packet) + return -ENOMEM; + + input_dev = devm_input_allocate_device(dev); + if (!input_dev) + return -ENOMEM; + + spi_set_drvdata(spi, ts); + + ts->packet = packet; + ts->spi = spi; + ts->input = input_dev; + + mutex_init(&ts->lock); + init_waitqueue_head(&ts->wait); + + pdata = dev_get_platdata(dev); + if (!pdata) { + pdata = ads7846_get_props(dev); + if (IS_ERR(pdata)) + return PTR_ERR(pdata); + } + + ts->model = pdata->model ? : 7846; + ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100; + ts->x_plate_ohms = pdata->x_plate_ohms ? : 400; + ts->vref_mv = pdata->vref_mv; + + if (pdata->debounce_max) { + ts->debounce_max = pdata->debounce_max; + if (ts->debounce_max < 2) + ts->debounce_max = 2; + ts->debounce_tol = pdata->debounce_tol; + ts->debounce_rep = pdata->debounce_rep; + ts->filter = ads7846_debounce_filter; + ts->filter_data = ts; + } else { + ts->filter = ads7846_no_filter; + } + + err = ads7846_setup_pendown(spi, ts, pdata); + if (err) + return err; + + if (pdata->penirq_recheck_delay_usecs) + ts->penirq_recheck_delay_usecs = + pdata->penirq_recheck_delay_usecs; + + ts->wait_for_sync = pdata->wait_for_sync ? : null_wait_for_sync; + + snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(dev)); + snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model); + + input_dev->name = ts->name; + input_dev->phys = ts->phys; + + input_dev->id.bustype = BUS_SPI; + input_dev->id.product = pdata->model; + + input_set_capability(input_dev, EV_KEY, BTN_TOUCH); + input_set_abs_params(input_dev, ABS_X, + pdata->x_min ? : 0, + pdata->x_max ? : MAX_12BIT, + 0, 0); + input_set_abs_params(input_dev, ABS_Y, + pdata->y_min ? : 0, + pdata->y_max ? : MAX_12BIT, + 0, 0); + if (ts->model != 7845) + input_set_abs_params(input_dev, ABS_PRESSURE, + pdata->pressure_min, pdata->pressure_max, 0, 0); + + /* + * Parse common framework properties. Must be done here to ensure the + * correct behaviour in case of using the legacy vendor bindings. The + * general binding value overrides the vendor specific one. + */ + touchscreen_parse_properties(ts->input, false, &ts->core_prop); + ts->pressure_max = input_abs_get_max(input_dev, ABS_PRESSURE) ? : ~0; + + /* + * Check if legacy ti,swap-xy binding is used instead of + * touchscreen-swapped-x-y + */ + if (!ts->core_prop.swap_x_y && pdata->swap_xy) { + swap(input_dev->absinfo[ABS_X], input_dev->absinfo[ABS_Y]); + ts->core_prop.swap_x_y = true; + } + + ads7846_setup_spi_msg(ts, pdata); + + ts->reg = devm_regulator_get(dev, "vcc"); + if (IS_ERR(ts->reg)) { + err = PTR_ERR(ts->reg); + dev_err(dev, "unable to get regulator: %d\n", err); + return err; + } + + err = regulator_enable(ts->reg); + if (err) { + dev_err(dev, "unable to enable regulator: %d\n", err); + return err; + } + + err = devm_add_action_or_reset(dev, ads7846_regulator_disable, ts->reg); + if (err) + return err; + + irq_flags = pdata->irq_flags ? : IRQF_TRIGGER_FALLING; + irq_flags |= IRQF_ONESHOT; + + err = devm_request_threaded_irq(dev, spi->irq, + ads7846_hard_irq, ads7846_irq, + irq_flags, dev->driver->name, ts); + if (err && err != -EPROBE_DEFER && !pdata->irq_flags) { + dev_info(dev, + "trying pin change workaround on irq %d\n", spi->irq); + irq_flags |= IRQF_TRIGGER_RISING; + err = devm_request_threaded_irq(dev, spi->irq, + ads7846_hard_irq, ads7846_irq, + irq_flags, dev->driver->name, + ts); + } + + if (err) { + dev_dbg(dev, "irq %d busy?\n", spi->irq); + return err; + } + + err = ads784x_hwmon_register(spi, ts); + if (err) + return err; + + dev_info(dev, "touchscreen, irq %d\n", spi->irq); + + /* + * Take a first sample, leaving nPENIRQ active and vREF off; avoid + * the touchscreen, in case it's not connected. + */ + if (ts->model == 7845) + ads7845_read12_ser(dev, PWRDOWN); + else + (void) ads7846_read12_ser(dev, READ_12BIT_SER(vaux)); + + err = devm_device_add_group(dev, &ads784x_attr_group); + if (err) + return err; + + err = input_register_device(input_dev); + if (err) + return err; + + device_init_wakeup(dev, pdata->wakeup); + + /* + * If device does not carry platform data we must have allocated it + * when parsing DT data. + */ + if (!dev_get_platdata(dev)) + devm_kfree(dev, (void *)pdata); + + return 0; +} + +static void ads7846_remove(struct spi_device *spi) +{ + struct ads7846 *ts = spi_get_drvdata(spi); + + ads7846_stop(ts); +} + +static struct spi_driver ads7846_driver = { + .driver = { + .name = "ads7846", + .pm = pm_sleep_ptr(&ads7846_pm), + .of_match_table = ads7846_dt_ids, + }, + .probe = ads7846_probe, + .remove = ads7846_remove, +}; + +module_spi_driver(ads7846_driver); + +MODULE_DESCRIPTION("ADS7846 TouchScreen Driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("spi:ads7846"); |