diff options
Diffstat (limited to 'drivers/input/touchscreen/ads7846.c')
| -rw-r--r-- | drivers/input/touchscreen/ads7846.c | 1519 |
1 files changed, 1519 insertions, 0 deletions
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c new file mode 100644 index 000000000..b53676823 --- /dev/null +++ b/drivers/input/touchscreen/ads7846.c @@ -0,0 +1,1519 @@ +/* + * 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 + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ +#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/interrupt.h> +#include <linux/slab.h> +#include <linux/pm.h> +#include <linux/of.h> +#include <linux/of_gpio.h> +#include <linux/of_device.h> +#include <linux/gpio.h> +#include <linux/spi/spi.h> +#include <linux/spi/ads7846.h> +#include <linux/regulator/consumer.h> +#include <linux/module.h> +#include <asm/irq.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 ts_event { + /* + * For portability, we can't read 12 bit values using SPI (which + * would make the controller deliver them as native byte order u16 + * with msbs zeroed). Instead, we read them as two 8-bit values, + * *** WHICH NEED BYTESWAPPING *** and range adjustment. + */ + u16 x; + u16 y; + u16 z1, z2; + bool ignore; + u8 x_buf[3]; + u8 y_buf[3]; +}; + +/* + * 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 { + u8 read_x, read_y, read_z1, read_z2, pwrdown; + u16 dummy; /* for the pwrdown read */ + struct ts_event tc; + /* for ads7845 with mpc5121 psc spi we use 3-byte buffers */ + u8 read_x_cmd[3], read_y_cmd[3], pwrdown_cmd[3]; +}; + +struct ads7846 { + struct input_dev *input; + char phys[32]; + char name[32]; + + struct spi_device *spi; + struct regulator *reg; + +#if IS_ENABLED(CONFIG_HWMON) + struct device *hwmon; +#endif + + 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 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; + void (*filter_cleanup)(void *data); + int (*get_pendown_state)(void); + int gpio_pendown; + + void (*wait_for_sync)(void); +}; + +/* 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)) + +static int get_pendown_state(struct ads7846 *ts) +{ + if (ts->get_pendown_state) + return ts->get_pendown_state(); + + return !gpio_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_usecs = ts->vref_delay_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 = container_of(kobj, struct device, 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) +{ + /* 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; + } + + ts->hwmon = hwmon_device_register_with_groups(&spi->dev, spi->modalias, + ts, ads7846_attr_groups); + + return PTR_ERR_OR_ZERO(ts->hwmon); +} + +static void ads784x_hwmon_unregister(struct spi_device *spi, + struct ads7846 *ts) +{ + if (ts->hwmon) + hwmon_device_unregister(ts->hwmon); +} + +#else +static inline int ads784x_hwmon_register(struct spi_device *spi, + struct ads7846 *ts) +{ + return 0; +} + +static inline void ads784x_hwmon_unregister(struct spi_device *spi, + struct ads7846 *ts) +{ +} +#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 *ts, struct spi_message *m) +{ + int value; + struct spi_transfer *t = + list_entry(m->transfers.prev, struct spi_transfer, transfer_list); + + if (ts->model == 7845) { + value = be16_to_cpup((__be16 *)&(((char *)t->rx_buf)[1])); + } else { + /* + * adjust: on-wire is a must-ignore bit, a BE12 value, then + * padding; built from two 8 bit values written msb-first. + */ + value = be16_to_cpup((__be16 *)t->rx_buf); + } + + /* enforce ADC output is 12 bits width */ + return (value >> 3) & 0xfff; +} + +static void ads7846_update_value(struct spi_message *m, int val) +{ + struct spi_transfer *t = + list_entry(m->transfers.prev, struct spi_transfer, transfer_list); + + *(u16 *)t->rx_buf = val; +} + +static void ads7846_read_state(struct ads7846 *ts) +{ + struct ads7846_packet *packet = ts->packet; + struct spi_message *m; + int msg_idx = 0; + int val; + int action; + int error; + + while (msg_idx < ts->msg_count) { + + 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->tc.ignore = true; + return; + } + + /* + * Last message is power down request, no need to convert + * or filter the value. + */ + if (msg_idx < ts->msg_count - 1) { + + val = ads7846_get_value(ts, m); + + action = ts->filter(ts->filter_data, msg_idx, &val); + switch (action) { + case ADS7846_FILTER_REPEAT: + continue; + + case ADS7846_FILTER_IGNORE: + packet->tc.ignore = true; + msg_idx = ts->msg_count - 1; + continue; + + case ADS7846_FILTER_OK: + ads7846_update_value(m, val); + packet->tc.ignore = false; + msg_idx++; + break; + + default: + BUG(); + } + } else { + msg_idx++; + } + } +} + +static void ads7846_report_state(struct ads7846 *ts) +{ + struct ads7846_packet *packet = ts->packet; + unsigned int Rt; + u16 x, y, z1, z2; + + /* + * ads7846_get_value() does in-place conversion (including byte swap) + * from on-the-wire format as part of debouncing to get stable + * readings. + */ + if (ts->model == 7845) { + x = *(u16 *)packet->tc.x_buf; + y = *(u16 *)packet->tc.y_buf; + z1 = 0; + z2 = 0; + } else { + x = packet->tc.x; + y = packet->tc.y; + z1 = packet->tc.z1; + z2 = packet->tc.z2; + } + + /* range filtering */ + if (x == MAX_12BIT) + x = 0; + + if (ts->model == 7843) { + Rt = ts->pressure_max / 2; + } else if (ts->model == 7845) { + if (get_pendown_state(ts)) + Rt = ts->pressure_max / 2; + else + Rt = 0; + dev_vdbg(&ts->spi->dev, "x/y: %d/%d, PD %d\n", x, y, Rt); + } 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->tc.ignore || Rt > ts->pressure_max) { + dev_vdbg(&ts->spi->dev, "ignored %d pressure %d\n", + packet->tc.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->swap_xy) + swap(x, y); + + if (!ts->pendown) { + input_report_key(input, BTN_TOUCH, 1); + ts->pendown = true; + dev_vdbg(&ts->spi->dev, "DOWN\n"); + } + + input_report_abs(input, ABS_X, x); + input_report_abs(input, ABS_Y, y); + 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 __maybe_unused 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 __maybe_unused 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 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) +{ + int err; + + /* + * 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 if (gpio_is_valid(pdata->gpio_pendown)) { + + err = gpio_request_one(pdata->gpio_pendown, GPIOF_IN, + "ads7846_pendown"); + if (err) { + dev_err(&spi->dev, + "failed to request/setup pendown GPIO%d: %d\n", + pdata->gpio_pendown, err); + return err; + } + + ts->gpio_pendown = pdata->gpio_pendown; + + if (pdata->gpio_pendown_debounce) + gpio_set_debounce(pdata->gpio_pendown, + pdata->gpio_pendown_debounce); + } else { + dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?\n"); + return -EINVAL; + } + + return 0; +} + +/* + * Set up the transfers to read touchscreen state; this assumes we + * use formula #2 for pressure, not #3. + */ +static void 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; + + 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; + + if (ts->model == 7845) { + packet->read_y_cmd[0] = READ_Y(vref); + packet->read_y_cmd[1] = 0; + packet->read_y_cmd[2] = 0; + x->tx_buf = &packet->read_y_cmd[0]; + x->rx_buf = &packet->tc.y_buf[0]; + x->len = 3; + spi_message_add_tail(x, m); + } else { + /* y- still on; turn on only y+ (and ADC) */ + packet->read_y = READ_Y(vref); + x->tx_buf = &packet->read_y; + x->len = 1; + spi_message_add_tail(x, m); + + x++; + x->rx_buf = &packet->tc.y; + x->len = 2; + spi_message_add_tail(x, m); + } + + /* + * The first sample after switching drivers can be low quality; + * optionally discard it, using a second one after the signals + * have had enough time to stabilize. + */ + if (pdata->settle_delay_usecs) { + x->delay_usecs = pdata->settle_delay_usecs; + + x++; + x->tx_buf = &packet->read_y; + x->len = 1; + spi_message_add_tail(x, m); + + x++; + x->rx_buf = &packet->tc.y; + x->len = 2; + spi_message_add_tail(x, m); + } + + ts->msg_count++; + m++; + spi_message_init(m); + m->context = ts; + + if (ts->model == 7845) { + x++; + packet->read_x_cmd[0] = READ_X(vref); + packet->read_x_cmd[1] = 0; + packet->read_x_cmd[2] = 0; + x->tx_buf = &packet->read_x_cmd[0]; + x->rx_buf = &packet->tc.x_buf[0]; + x->len = 3; + spi_message_add_tail(x, m); + } else { + /* turn y- off, x+ on, then leave in lowpower */ + x++; + packet->read_x = READ_X(vref); + x->tx_buf = &packet->read_x; + x->len = 1; + spi_message_add_tail(x, m); + + x++; + x->rx_buf = &packet->tc.x; + x->len = 2; + spi_message_add_tail(x, m); + } + + /* ... maybe discard first sample ... */ + if (pdata->settle_delay_usecs) { + x->delay_usecs = pdata->settle_delay_usecs; + + x++; + x->tx_buf = &packet->read_x; + x->len = 1; + spi_message_add_tail(x, m); + + x++; + x->rx_buf = &packet->tc.x; + x->len = 2; + spi_message_add_tail(x, m); + } + + /* turn y+ off, x- on; we'll use formula #2 */ + if (ts->model == 7846) { + ts->msg_count++; + m++; + spi_message_init(m); + m->context = ts; + + x++; + packet->read_z1 = READ_Z1(vref); + x->tx_buf = &packet->read_z1; + x->len = 1; + spi_message_add_tail(x, m); + + x++; + x->rx_buf = &packet->tc.z1; + x->len = 2; + spi_message_add_tail(x, m); + + /* ... maybe discard first sample ... */ + if (pdata->settle_delay_usecs) { + x->delay_usecs = pdata->settle_delay_usecs; + + x++; + x->tx_buf = &packet->read_z1; + x->len = 1; + spi_message_add_tail(x, m); + + x++; + x->rx_buf = &packet->tc.z1; + x->len = 2; + spi_message_add_tail(x, m); + } + + ts->msg_count++; + m++; + spi_message_init(m); + m->context = ts; + + x++; + packet->read_z2 = READ_Z2(vref); + x->tx_buf = &packet->read_z2; + x->len = 1; + spi_message_add_tail(x, m); + + x++; + x->rx_buf = &packet->tc.z2; + x->len = 2; + spi_message_add_tail(x, m); + + /* ... maybe discard first sample ... */ + if (pdata->settle_delay_usecs) { + x->delay_usecs = pdata->settle_delay_usecs; + + x++; + x->tx_buf = &packet->read_z2; + x->len = 1; + spi_message_add_tail(x, m); + + x++; + x->rx_buf = &packet->tc.z2; + x->len = 2; + spi_message_add_tail(x, m); + } + } + + /* power down */ + ts->msg_count++; + m++; + spi_message_init(m); + m->context = ts; + + if (ts->model == 7845) { + x++; + packet->pwrdown_cmd[0] = PWRDOWN; + packet->pwrdown_cmd[1] = 0; + packet->pwrdown_cmd[2] = 0; + x->tx_buf = &packet->pwrdown_cmd[0]; + x->len = 3; + } else { + x++; + packet->pwrdown = PWRDOWN; + x->tx_buf = &packet->pwrdown; + x->len = 1; + spi_message_add_tail(x, m); + + x++; + x->rx_buf = &packet->dummy; + x->len = 2; + } + + CS_CHANGE(*x); + spi_message_add_tail(x, m); +} + +#ifdef CONFIG_OF +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_probe_dt(struct device *dev) +{ + struct ads7846_platform_data *pdata; + struct device_node *node = dev->of_node; + const struct of_device_id *match; + + if (!node) { + dev_err(dev, "Device does not have associated DT data\n"); + return ERR_PTR(-EINVAL); + } + + match = of_match_device(ads7846_dt_ids, dev); + if (!match) { + dev_err(dev, "Unknown device model\n"); + return ERR_PTR(-EINVAL); + } + + pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL); + if (!pdata) + return ERR_PTR(-ENOMEM); + + pdata->model = (unsigned long)match->data; + + of_property_read_u16(node, "ti,vref-delay-usecs", + &pdata->vref_delay_usecs); + of_property_read_u16(node, "ti,vref-mv", &pdata->vref_mv); + pdata->keep_vref_on = of_property_read_bool(node, "ti,keep-vref-on"); + + pdata->swap_xy = of_property_read_bool(node, "ti,swap-xy"); + + of_property_read_u16(node, "ti,settle-delay-usec", + &pdata->settle_delay_usecs); + of_property_read_u16(node, "ti,penirq-recheck-delay-usecs", + &pdata->penirq_recheck_delay_usecs); + + of_property_read_u16(node, "ti,x-plate-ohms", &pdata->x_plate_ohms); + of_property_read_u16(node, "ti,y-plate-ohms", &pdata->y_plate_ohms); + + of_property_read_u16(node, "ti,x-min", &pdata->x_min); + of_property_read_u16(node, "ti,y-min", &pdata->y_min); + of_property_read_u16(node, "ti,x-max", &pdata->x_max); + of_property_read_u16(node, "ti,y-max", &pdata->y_max); + + of_property_read_u16(node, "ti,pressure-min", &pdata->pressure_min); + of_property_read_u16(node, "ti,pressure-max", &pdata->pressure_max); + + of_property_read_u16(node, "ti,debounce-max", &pdata->debounce_max); + of_property_read_u16(node, "ti,debounce-tol", &pdata->debounce_tol); + of_property_read_u16(node, "ti,debounce-rep", &pdata->debounce_rep); + + of_property_read_u32(node, "ti,pendown-gpio-debounce", + &pdata->gpio_pendown_debounce); + + pdata->wakeup = of_property_read_bool(node, "wakeup-source") || + of_property_read_bool(node, "linux,wakeup"); + + pdata->gpio_pendown = of_get_named_gpio(dev->of_node, "pendown-gpio", 0); + + return pdata; +} +#else +static const struct ads7846_platform_data *ads7846_probe_dt(struct device *dev) +{ + dev_err(dev, "no platform data defined\n"); + return ERR_PTR(-EINVAL); +} +#endif + +static int ads7846_probe(struct spi_device *spi) +{ + const struct ads7846_platform_data *pdata; + struct ads7846 *ts; + struct ads7846_packet *packet; + struct input_dev *input_dev; + unsigned long irq_flags; + int err; + + if (!spi->irq) { + dev_dbg(&spi->dev, "no IRQ?\n"); + return -EINVAL; + } + + /* don't exceed max specified sample rate */ + if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) { + dev_err(&spi->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_0; + err = spi_setup(spi); + if (err < 0) + return err; + + ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL); + packet = kzalloc(sizeof(struct ads7846_packet), GFP_KERNEL); + input_dev = input_allocate_device(); + if (!ts || !packet || !input_dev) { + err = -ENOMEM; + goto err_free_mem; + } + + 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(&spi->dev); + if (!pdata) { + pdata = ads7846_probe_dt(&spi->dev); + if (IS_ERR(pdata)) { + err = PTR_ERR(pdata); + goto err_free_mem; + } + } + + ts->model = pdata->model ? : 7846; + ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100; + ts->x_plate_ohms = pdata->x_plate_ohms ? : 400; + ts->pressure_max = pdata->pressure_max ? : ~0; + + ts->vref_mv = pdata->vref_mv; + ts->swap_xy = pdata->swap_xy; + + if (pdata->filter != NULL) { + if (pdata->filter_init != NULL) { + err = pdata->filter_init(pdata, &ts->filter_data); + if (err < 0) + goto err_free_mem; + } + ts->filter = pdata->filter; + ts->filter_cleanup = pdata->filter_cleanup; + } else 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) + goto err_cleanup_filter; + + 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(&spi->dev)); + snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model); + + input_dev->name = ts->name; + input_dev->phys = ts->phys; + input_dev->dev.parent = &spi->dev; + + input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS); + input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(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); + input_set_abs_params(input_dev, ABS_PRESSURE, + pdata->pressure_min, pdata->pressure_max, 0, 0); + + ads7846_setup_spi_msg(ts, pdata); + + ts->reg = regulator_get(&spi->dev, "vcc"); + if (IS_ERR(ts->reg)) { + err = PTR_ERR(ts->reg); + dev_err(&spi->dev, "unable to get regulator: %d\n", err); + goto err_free_gpio; + } + + err = regulator_enable(ts->reg); + if (err) { + dev_err(&spi->dev, "unable to enable regulator: %d\n", err); + goto err_put_regulator; + } + + irq_flags = pdata->irq_flags ? : IRQF_TRIGGER_FALLING; + irq_flags |= IRQF_ONESHOT; + + err = request_threaded_irq(spi->irq, ads7846_hard_irq, ads7846_irq, + irq_flags, spi->dev.driver->name, ts); + if (err && !pdata->irq_flags) { + dev_info(&spi->dev, + "trying pin change workaround on irq %d\n", spi->irq); + irq_flags |= IRQF_TRIGGER_RISING; + err = request_threaded_irq(spi->irq, + ads7846_hard_irq, ads7846_irq, + irq_flags, spi->dev.driver->name, ts); + } + + if (err) { + dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq); + goto err_disable_regulator; + } + + err = ads784x_hwmon_register(spi, ts); + if (err) + goto err_free_irq; + + dev_info(&spi->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(&spi->dev, PWRDOWN); + else + (void) ads7846_read12_ser(&spi->dev, READ_12BIT_SER(vaux)); + + err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group); + if (err) + goto err_remove_hwmon; + + err = input_register_device(input_dev); + if (err) + goto err_remove_attr_group; + + device_init_wakeup(&spi->dev, pdata->wakeup); + + /* + * If device does not carry platform data we must have allocated it + * when parsing DT data. + */ + if (!dev_get_platdata(&spi->dev)) + devm_kfree(&spi->dev, (void *)pdata); + + return 0; + + err_remove_attr_group: + sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group); + err_remove_hwmon: + ads784x_hwmon_unregister(spi, ts); + err_free_irq: + free_irq(spi->irq, ts); + err_disable_regulator: + regulator_disable(ts->reg); + err_put_regulator: + regulator_put(ts->reg); + err_free_gpio: + if (!ts->get_pendown_state) + gpio_free(ts->gpio_pendown); + err_cleanup_filter: + if (ts->filter_cleanup) + ts->filter_cleanup(ts->filter_data); + err_free_mem: + input_free_device(input_dev); + kfree(packet); + kfree(ts); + return err; +} + +static int ads7846_remove(struct spi_device *spi) +{ + struct ads7846 *ts = spi_get_drvdata(spi); + + sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group); + + ads7846_disable(ts); + free_irq(ts->spi->irq, ts); + + input_unregister_device(ts->input); + + ads784x_hwmon_unregister(spi, ts); + + regulator_put(ts->reg); + + if (!ts->get_pendown_state) { + /* + * If we are not using specialized pendown method we must + * have been relying on gpio we set up ourselves. + */ + gpio_free(ts->gpio_pendown); + } + + if (ts->filter_cleanup) + ts->filter_cleanup(ts->filter_data); + + kfree(ts->packet); + kfree(ts); + + dev_dbg(&spi->dev, "unregistered touchscreen\n"); + + return 0; +} + +static struct spi_driver ads7846_driver = { + .driver = { + .name = "ads7846", + .pm = &ads7846_pm, + .of_match_table = of_match_ptr(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"); |