diff options
Diffstat (limited to 'drivers/input/touchscreen/ads7846.c')
| -rw-r--r-- | drivers/input/touchscreen/ads7846.c | 625 |
1 files changed, 625 insertions, 0 deletions
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c new file mode 100644 index 0000000..dd8c6a9 --- /dev/null +++ b/drivers/input/touchscreen/ads7846.c @@ -0,0 +1,625 @@ +/* + * ADS7846 based touchscreen and sensor driver + * + * Copyright (c) 2005 David Brownell + * + * 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/device.h> +#include <linux/init.h> +#include <linux/delay.h> +#include <linux/input.h> +#include <linux/interrupt.h> +#include <linux/slab.h> +#include <linux/spi/spi.h> +#include <linux/spi/ads7846.h> + +#ifdef CONFIG_ARM +#include <asm/mach-types.h> +#ifdef CONFIG_ARCH_OMAP +#include <asm/arch/gpio.h> +#endif + +#else +#define set_irq_type(irq,type) do{}while(0) +#endif + + +/* + * This code has been lightly tested on an ads7846. + * Support for ads7843 and ads7845 has only been stubbed in. + * + * Not yet done: investigate the values reported. Are x/y/pressure + * event values sane enough for X11? How accurate are the temperature + * and voltage readings? (System-specific calibration should support + * accuracy of 0.3 degrees C; otherwise it's 2.0 degrees.) + * + * 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. + */ + +#define TS_POLL_PERIOD msecs_to_jiffies(10) + +struct ts_event { + /* For portability, we can't read 12 bit values using SPI (which + * would make the controller deliver them as native byteorder u16 + * with msbs zeroed). Instead, we read them as two 8-byte values, + * which need byteswapping then range adjustment. + */ + __be16 x; + __be16 y; + __be16 z1, z2; +}; + +struct ads7846 { + struct input_dev input; + char phys[32]; + + struct spi_device *spi; + u16 model; + u16 vref_delay_usecs; + u16 x_plate_ohms; + + struct ts_event tc; + + struct spi_transfer xfer[8]; + struct spi_message msg; + + spinlock_t lock; + struct timer_list timer; /* P: lock */ + unsigned pendown:1; /* P: lock */ + unsigned pending:1; /* P: lock */ +// FIXME remove "irq_disabled" + unsigned irq_disabled:1; /* P: lock */ +}; + +/* 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) /* lowpower 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) (ADS_START | ADS_A2A1A0_d_ ## x \ + | ADS_12_BIT | ADS_DFR) + +static const u8 read_y = READ_12BIT_DFR(y) | ADS_PD10_ADC_ON; +static const u8 read_z1 = READ_12BIT_DFR(z1) | ADS_PD10_ADC_ON; +static const u8 read_z2 = READ_12BIT_DFR(z2) | ADS_PD10_ADC_ON; +static const u8 read_x = READ_12BIT_DFR(x) | ADS_PD10_PDOWN; /* 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) + +static const u8 ref_on = READ_12BIT_DFR(x) | ADS_PD10_ALL_ON; +static const u8 ref_off = READ_12BIT_DFR(y) | ADS_PD10_PDOWN; + +/*--------------------------------------------------------------------------*/ + +/* + * Non-touchscreen sensors only use single-ended conversions. + */ + +struct ser_req { + u8 command; + u16 scratch; + __be16 sample; + struct spi_message msg; + struct spi_transfer xfer[6]; +}; + +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 = kzalloc(sizeof *req, SLAB_KERNEL); + int status; + int sample; + int i; + + if (!req) + return -ENOMEM; + + INIT_LIST_HEAD(&req->msg.transfers); + + /* activate reference, so it has time to settle; */ + req->xfer[0].tx_buf = &ref_on; + req->xfer[0].len = 1; + req->xfer[1].rx_buf = &req->scratch; + req->xfer[1].len = 2; + + /* + * for external VREF, 0 usec (and assume it's always on); + * for 1uF, use 800 usec; + * no cap, 100 usec. + */ + req->xfer[1].delay_usecs = ts->vref_delay_usecs; + + /* take sample */ + req->command = (u8) command; + req->xfer[2].tx_buf = &req->command; + req->xfer[2].len = 1; + req->xfer[3].rx_buf = &req->sample; + req->xfer[3].len = 2; + + /* REVISIT: take a few more samples, and compare ... */ + + /* turn off reference */ + req->xfer[4].tx_buf = &ref_off; + req->xfer[4].len = 1; + req->xfer[5].rx_buf = &req->scratch; + req->xfer[5].len = 2; + + CS_CHANGE(req->xfer[5]); + + /* group all the transfers together, so we can't interfere with + * reading touchscreen state; disable penirq while sampling + */ + for (i = 0; i < 6; i++) + spi_message_add_tail(&req->xfer[i], &req->msg); + + disable_irq(spi->irq); + status = spi_sync(spi, &req->msg); + enable_irq(spi->irq); + + if (req->msg.status) + status = req->msg.status; + sample = be16_to_cpu(req->sample); + sample = sample >> 4; + kfree(req); + + return status ? status : sample; +} + +#define SHOW(name) static ssize_t \ +name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \ +{ \ + ssize_t v = ads7846_read12_ser(dev, \ + READ_12BIT_SER(name) | ADS_PD10_ALL_ON); \ + if (v < 0) \ + return v; \ + return sprintf(buf, "%u\n", (unsigned) v); \ +} \ +static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL); + +SHOW(temp0) +SHOW(temp1) +SHOW(vaux) +SHOW(vbatt) + +/*--------------------------------------------------------------------------*/ + +/* + * PENIRQ only kicks the timer. The timer only reissues the SPI transfer, + * to retrieve touchscreen status. + * + * The SPI transfer completion callback does the real work. It reports + * touchscreen events and reactivates the timer (or IRQ) as appropriate. + */ + +static void ads7846_rx(void *ads) +{ + struct ads7846 *ts = ads; + unsigned Rt; + unsigned sync = 0; + u16 x, y, z1, z2; + unsigned long flags; + + /* adjust: 12 bit samples (left aligned), built from + * two 8 bit values writen msb-first. + */ + x = be16_to_cpu(ts->tc.x) >> 4; + y = be16_to_cpu(ts->tc.y) >> 4; + z1 = be16_to_cpu(ts->tc.z1) >> 4; + z2 = be16_to_cpu(ts->tc.z2) >> 4; + + /* range filtering */ + if (x == MAX_12BIT) + x = 0; + + if (x && z1 && ts->spi->dev.power.power_state.event == PM_EVENT_ON) { + /* compute touch pressure resistance using equation #2 */ + Rt = z2; + Rt -= z1; + Rt *= x; + Rt *= ts->x_plate_ohms; + Rt /= z1; + Rt = (Rt + 2047) >> 12; + } else + Rt = 0; + + /* NOTE: "pendown" is inferred from pressure; we don't rely on + * being able to check nPENIRQ status, or "friendly" trigger modes + * (both-edges is much better than just-falling or low-level). + * + * REVISIT: some boards may require reading nPENIRQ; it's + * needed on 7843. and 7845 reads pressure differently... + * + * REVISIT: the touchscreen might not be connected; this code + * won't notice that, even if nPENIRQ never fires ... + */ + if (!ts->pendown && Rt != 0) { + input_report_key(&ts->input, BTN_TOUCH, 1); + sync = 1; + } else if (ts->pendown && Rt == 0) { + input_report_key(&ts->input, BTN_TOUCH, 0); + sync = 1; + } + + if (Rt) { + input_report_abs(&ts->input, ABS_X, x); + input_report_abs(&ts->input, ABS_Y, y); + input_report_abs(&ts->input, ABS_PRESSURE, Rt); + sync = 1; + } + if (sync) + input_sync(&ts->input); + +#ifdef VERBOSE + if (Rt || ts->pendown) + pr_debug("%s: %d/%d/%d%s\n", ts->spi->dev.bus_id, + x, y, Rt, Rt ? "" : " UP"); +#endif + + /* don't retrigger while we're suspended */ + spin_lock_irqsave(&ts->lock, flags); + + ts->pendown = (Rt != 0); + ts->pending = 0; + + if (ts->spi->dev.power.power_state.event == PM_EVENT_ON) { + if (ts->pendown) + mod_timer(&ts->timer, jiffies + TS_POLL_PERIOD); + else if (ts->irq_disabled) { + ts->irq_disabled = 0; + enable_irq(ts->spi->irq); + } + } + + spin_unlock_irqrestore(&ts->lock, flags); +} + +static void ads7846_timer(unsigned long handle) +{ + struct ads7846 *ts = (void *)handle; + int status = 0; + unsigned long flags; + + spin_lock_irqsave(&ts->lock, flags); + if (!ts->pending) { + ts->pending = 1; + if (!ts->irq_disabled) { + ts->irq_disabled = 1; + disable_irq(ts->spi->irq); + } + status = spi_async(ts->spi, &ts->msg); + if (status) + dev_err(&ts->spi->dev, "spi_async --> %d\n", + status); + } + spin_unlock_irqrestore(&ts->lock, flags); +} + +static irqreturn_t ads7846_irq(int irq, void *handle, struct pt_regs *regs) +{ + ads7846_timer((unsigned long) handle); + return IRQ_HANDLED; +} + +/*--------------------------------------------------------------------------*/ + +static int +ads7846_suspend(struct spi_device *spi, pm_message_t message) +{ + struct ads7846 *ts = dev_get_drvdata(&spi->dev); + unsigned long flags; + + spin_lock_irqsave(&ts->lock, flags); + + spi->dev.power.power_state = message; + + /* are we waiting for IRQ, or polling? */ + if (!ts->pendown) { + if (!ts->irq_disabled) { + ts->irq_disabled = 1; + disable_irq(ts->spi->irq); + } + } else { + /* polling; force a final SPI completion; + * that will clean things up neatly + */ + if (!ts->pending) + mod_timer(&ts->timer, jiffies); + + while (ts->pendown || ts->pending) { + spin_unlock_irqrestore(&ts->lock, flags); + udelay(10); + spin_lock_irqsave(&ts->lock, flags); + } + } + + /* we know the chip's in lowpower mode since we always + * leave it that way after every request + */ + + spin_unlock_irqrestore(&ts->lock, flags); + return 0; +} + +static int ads7846_resume(struct spi_device *spi) +{ + struct ads7846 *ts = dev_get_drvdata(&spi->dev); + + ts->irq_disabled = 0; + enable_irq(ts->spi->irq); + spi->dev.power.power_state = PMSG_ON; + return 0; +} + +static int __devinit ads7846_probe(struct spi_device *spi) +{ + struct ads7846 *ts; + struct ads7846_platform_data *pdata = spi->dev.platform_data; + struct spi_transfer *x; + int i; + + if (!spi->irq) { + dev_dbg(&spi->dev, "no IRQ?\n"); + return -ENODEV; + } + + if (!pdata) { + dev_dbg(&spi->dev, "no platform data?\n"); + return -ENODEV; + } + + /* don't exceed max specified sample rate */ + if (spi->max_speed_hz > (125000 * 16)) { + dev_dbg(&spi->dev, "f(sample) %d KHz?\n", + (spi->max_speed_hz/16)/1000); + return -EINVAL; + } + + /* We'd set the wordsize to 12 bits ... except that some controllers + * will then treat the 8 bit command words as 12 bits (and drop the + * four MSBs of the 12 bit result). Result: inputs must be shifted + * to discard the four garbage LSBs. + */ + + if (!(ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL))) + return -ENOMEM; + + dev_set_drvdata(&spi->dev, ts); + + ts->spi = spi; + spi->dev.power.power_state = PMSG_ON; + + init_timer(&ts->timer); + ts->timer.data = (unsigned long) ts; + ts->timer.function = ads7846_timer; + + ts->model = pdata->model ? : 7846; + ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100; + ts->x_plate_ohms = pdata->x_plate_ohms ? : 400; + + init_input_dev(&ts->input); + + ts->input.dev = &spi->dev; + ts->input.name = "ADS784x Touchscreen"; + snprintf(ts->phys, sizeof ts->phys, "%s/input0", spi->dev.bus_id); + ts->input.phys = ts->phys; + + ts->input.evbit[0] = BIT(EV_KEY) | BIT(EV_ABS); + ts->input.keybit[LONG(BTN_TOUCH)] = BIT(BTN_TOUCH); + input_set_abs_params(&ts->input, ABS_X, + pdata->x_min ? : 0, + pdata->x_max ? : MAX_12BIT, + 0, 0); + input_set_abs_params(&ts->input, ABS_Y, + pdata->y_min ? : 0, + pdata->y_max ? : MAX_12BIT, + 0, 0); + input_set_abs_params(&ts->input, ABS_PRESSURE, + pdata->pressure_min, pdata->pressure_max, 0, 0); + + input_register_device(&ts->input); + + /* set up the transfers to read touchscreen state; this assumes we + * use formula #2 for pressure, not #3. + */ + x = ts->xfer; + + /* y- still on; turn on only y+ (and ADC) */ + x->tx_buf = &read_y; + x->len = 1; + x++; + x->rx_buf = &ts->tc.y; + x->len = 2; + x++; + + /* turn y+ off, x- on; we'll use formula #2 */ + if (ts->model == 7846) { + x->tx_buf = &read_z1; + x->len = 1; + x++; + x->rx_buf = &ts->tc.z1; + x->len = 2; + x++; + + x->tx_buf = &read_z2; + x->len = 1; + x++; + x->rx_buf = &ts->tc.z2; + x->len = 2; + x++; + } + + /* turn y- off, x+ on, then leave in lowpower */ + x->tx_buf = &read_x; + x->len = 1; + x++; + x->rx_buf = &ts->tc.x; + x->len = 2; + x++; + + CS_CHANGE(x[-1]); + + for (i = 0; i < x - ts->xfer; i++) + spi_message_add_tail(&ts->xfer[i], &ts->msg); + ts->msg.complete = ads7846_rx; + ts->msg.context = ts; + + if (request_irq(spi->irq, ads7846_irq, SA_SAMPLE_RANDOM, + spi->dev.bus_id, ts)) { + dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq); + input_unregister_device(&ts->input); + kfree(ts); + return -EBUSY; + } + set_irq_type(spi->irq, IRQT_FALLING); + + dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq); + + /* take a first sample, leaving nPENIRQ active; avoid + * the touchscreen, in case it's not connected. + */ + (void) ads7846_read12_ser(&spi->dev, + READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON); + + /* ads7843/7845 don't have temperature sensors, and + * use the other sensors a bit differently too + */ + if (ts->model == 7846) { + device_create_file(&spi->dev, &dev_attr_temp0); + device_create_file(&spi->dev, &dev_attr_temp1); + } + if (ts->model != 7845) + device_create_file(&spi->dev, &dev_attr_vbatt); + device_create_file(&spi->dev, &dev_attr_vaux); + + return 0; +} + +static int __devexit ads7846_remove(struct spi_device *spi) +{ + struct ads7846 *ts = dev_get_drvdata(&spi->dev); + + ads7846_suspend(spi, PMSG_SUSPEND); + free_irq(ts->spi->irq, ts); + if (ts->irq_disabled) + enable_irq(ts->spi->irq); + + if (ts->model == 7846) { + device_remove_file(&spi->dev, &dev_attr_temp0); + device_remove_file(&spi->dev, &dev_attr_temp1); + } + if (ts->model != 7845) + device_remove_file(&spi->dev, &dev_attr_vbatt); + device_remove_file(&spi->dev, &dev_attr_vaux); + + input_unregister_device(&ts->input); + kfree(ts); + + dev_dbg(&spi->dev, "unregistered touchscreen\n"); + return 0; +} + +static struct spi_driver ads7846_driver = { + .driver = { + .name = "ads7846", + .bus = &spi_bus_type, + .owner = THIS_MODULE, + }, + .probe = ads7846_probe, + .remove = __devexit_p(ads7846_remove), + .suspend = ads7846_suspend, + .resume = ads7846_resume, +}; + +static int __init ads7846_init(void) +{ + /* grr, board-specific init should stay out of drivers!! */ + +#ifdef CONFIG_ARCH_OMAP + if (machine_is_omap_osk()) { + /* GPIO4 = PENIRQ; GPIO6 = BUSY */ + omap_request_gpio(4); + omap_set_gpio_direction(4, 1); + omap_request_gpio(6); + omap_set_gpio_direction(6, 1); + } + // also TI 1510 Innovator, bitbanging through FPGA + // also Nokia 770 + // also Palm Tungsten T2 +#endif + + // PXA: + // also Dell Axim X50 + // also HP iPaq H191x/H192x/H415x/H435x + // also Intel Lubbock (additional to UCB1400; as temperature sensor) + // also Sharp Zaurus C7xx, C8xx (corgi/sheperd/husky) + + // Atmel at91sam9261-EK uses ads7843 + + // also various AMD Au1x00 devel boards + + return spi_register_driver(&ads7846_driver); +} +module_init(ads7846_init); + +static void __exit ads7846_exit(void) +{ + spi_unregister_driver(&ads7846_driver); + +#ifdef CONFIG_ARCH_OMAP + if (machine_is_omap_osk()) { + omap_free_gpio(4); + omap_free_gpio(6); + } +#endif + +} +module_exit(ads7846_exit); + +MODULE_DESCRIPTION("ADS7846 TouchScreen Driver"); +MODULE_LICENSE("GPL"); |
