* ADS7846 based touchscreen and sensor driver
*
* Copyright (c) 2005 David Brownell
- * Copyright (c) 2006 Imre Deak <imre.deak@nokia.com>
+ * Copyright (c) 2006 Nokia Corporation
+ * Various changes: Imre Deak <imre.deak@nokia.com>
*
* Using code from:
* - corgi_ts.c
* 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/hwmon.h>
#include <linux/init.h>
+#include <linux/err.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>
+#include <asm/irq.h>
#ifdef CONFIG_ARM
#include <asm/mach-types.h>
/*
* This code has been heavily tested on a Nokia 770, and lightly
- * tested on an other ads7846 device.
+ * tested on other ads7846 devices (OSK/Mistral, Lubbock).
* Support for ads7843 and ads7845 has only been stubbed in.
*
- * Not yet done: 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.)
- *
* 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 platforms' IRQ handling is fixed.
+ * 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
char phys[32];
struct spi_device *spi;
+ struct class_device *hwmon;
u16 model;
u16 vref_delay_usecs;
u16 x_plate_ohms;
- u16 pressure_max;
u8 read_x, read_y, read_z1, read_z2, pwrdown;
u16 dummy; /* for the pwrdown read */
struct ts_event tc;
- u16 last_x;
- u16 last_y;
- u16 last_pressure;
struct spi_transfer xfer[10];
struct spi_message msg[5];
/*
* 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.
+ *
+ * FIXME make external vREF_mV be a module option, and use that as needed...
*/
+static const unsigned vREF_mV = 2500;
struct ser_req {
u8 ref_on;
struct ser_req *req = kzalloc(sizeof *req, SLAB_KERNEL);
int status;
int sample;
- int i;
+ int use_internal;
if (!req)
return -ENOMEM;
spi_message_init(&req->msg);
- /* activate reference, so it has time to settle; */
- req->ref_on = REF_ON;
- req->xfer[0].tx_buf = &req->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;
+ /* FIXME boards with ads7846 might use external vref instead ... */
+ use_internal = (ts->model == 7846);
+
+ /* maybe turn on internal vREF, and let it settle */
+ if (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);
+ }
/* 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 ... */
- /* turn off reference */
- req->ref_off = REF_OFF;
- req->xfer[4].tx_buf = &req->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);
+ /* maybe off internal vREF */
+ if (use_internal) {
+ req->ref_off = REF_OFF;
+ 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);
+ }
disable_irq(spi->irq);
status = spi_sync(spi, &req->msg);
if (req->msg.status)
status = req->msg.status;
+
+ /* on-wire is a must-ignore bit, a BE12 value, then padding */
sample = be16_to_cpu(req->sample);
- sample = sample >> 4;
- kfree(req);
+ sample = sample >> 3;
+ sample &= 0x0fff;
+ kfree(req);
return status ? status : sample;
}
-#define SHOW(name) static ssize_t \
+#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(dev, \
- READ_12BIT_SER(name) | ADS_PD10_ALL_ON); \
+ READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
if (v < 0) \
return v; \
- return sprintf(buf, "%u\n", (unsigned) v); \
+ return sprintf(buf, "%u\n", adjust(ts, v)); \
} \
static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
-SHOW(temp0)
-SHOW(temp1)
-SHOW(vaux)
-SHOW(vbatt)
+
+/* Sysfs conventions report temperatures in millidegrees Celcius.
+ * We 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 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 *= 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 int is_pen_down(struct device *dev)
{
const char *buf, size_t count)
{
struct ads7846 *ts = dev_get_drvdata(dev);
- unsigned long flags;
char *endp;
int i;
i = simple_strtoul(buf, &endp, 10);
- spin_lock_irqsave(&ts->lock, flags);
+ spin_lock_irq(&ts->lock);
if (i)
ads7846_disable(ts);
else
ads7846_enable(ts);
- spin_unlock_irqrestore(&ts->lock, flags);
+ spin_unlock_irq(&ts->lock);
return count;
}
u16 x, y, z1, z2;
unsigned long flags;
- /* adjust: 12 bit samples (left aligned), built from
- * two 8 bit values writen msb-first.
+ /* adjust: on-wire is a must-ignore bit, a BE12 value, then padding;
+ * built from two 8 bit values written msb-first.
*/
- x = ts->tc.x >> 3;
- y = ts->tc.y >> 3;
- z1 = ts->tc.z1 >> 3;
- z2 = ts->tc.z2 >> 3;
+ x = (be16_to_cpu(ts->tc.x) >> 3) & 0x0fff;
+ y = (be16_to_cpu(ts->tc.y) >> 3) & 0x0fff;
+ z1 = (be16_to_cpu(ts->tc.z1) >> 3) & 0x0fff;
+ z2 = (be16_to_cpu(ts->tc.z2) >> 3) & 0x0fff;
/* range filtering */
if (x == MAX_12BIT)
} else
Rt = 0;
- if (Rt > ts->pressure_max) {
- if (ts->last_pressure) {
- x = ts->last_x;
- y = ts->last_y;
- }
- Rt = ts->pressure_max;
- }
-
- ts->last_x = x;
- ts->last_y = y;
- ts->last_pressure = Rt;
-
/* 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).
t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
val = (*(u16 *)t->rx_buf) >> 3;
- if (!ts->read_cnt || (abs(ts->last_read - val) > ts->debounce_tol &&
- ts->read_cnt < ts->debounce_max)) {
+ if (!ts->read_cnt || (abs(ts->last_read - val) > ts->debounce_tol
+ && ts->read_cnt < ts->debounce_max)) {
/* Repeat it, if this was the first read or the read wasn't
- * consistent enough */
+ * consistent enough
+ */
ts->read_cnt++;
ts->last_read = val;
} else {
spin_lock_irqsave(&ts->lock, flags);
if (likely(!ts->irq_disabled && !ts->disabled)) {
if (!ts->irq_disabled) {
+ /* REVISIT irq logic for many ARM chips has cloned a
+ * bug wherein disabling an irq in its handler won't
+ * work;(it's disabled lazily, and too late to work.
+ * until all their irq logic is fixed, we must shadow
+ * that state here.
+ */
ts->irq_disabled = 1;
- /* The following has at the moment no effect whatsoever
- * on OMAP, that's why we maintain the disabled
- * state ourselves */
+
disable_irq(ts->spi->irq);
}
if (!ts->pending) {
disable_irq(ts->spi->irq);
}
} else {
- unsigned long flags;
-
/* polling; force a final SPI completion;
* that will clean things up neatly
*/
mod_timer(&ts->timer, jiffies);
while (ts->pendown || ts->pending) {
- spin_unlock_irqrestore(&ts->lock, flags);
+ spin_unlock_irq(&ts->lock);
msleep(1);
- spin_lock_irqsave(&ts->lock, flags);
+ spin_lock_irq(&ts->lock);
}
}
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);
+ spin_lock_irq(&ts->lock);
spi->dev.power.power_state = message;
ads7846_disable(ts);
- spin_unlock_irqrestore(&ts->lock, flags);
+ spin_unlock_irq(&ts->lock);
return 0;
static int ads7846_resume(struct spi_device *spi)
{
struct ads7846 *ts = dev_get_drvdata(&spi->dev);
- unsigned long flags;
- spin_lock_irqsave(&ts->lock, flags);
+ spin_lock_irq(&ts->lock);
spi->dev.power.power_state = PMSG_ON;
ads7846_enable(ts);
- spin_unlock_irqrestore(&ts->lock, flags);
+ spin_unlock_irq(&ts->lock);
return 0;
}
{
struct ads7846 *ts;
struct input_dev *input_dev;
+ struct class_device *hwmon = ERR_PTR(-ENOMEM);
struct ads7846_platform_data *pdata = spi->dev.platform_data;
struct spi_message *m;
struct spi_transfer *x;
/* 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.
+ * to discard the four garbage LSBs. (Also, not all controllers can
+ * support 12 bit words.)
*/
ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
input_dev = input_allocate_device();
- if (!ts || !input_dev) {
+ hwmon = hwmon_device_register(&spi->dev);
+ if (!ts || !input_dev || IS_ERR(hwmon)) {
err = -ENOMEM;
goto err_free_mem;
}
ts->spi = spi;
ts->input = input_dev;
+ ts->hwmon = hwmon;
init_timer(&ts->timer);
ts->timer.data = (unsigned long) ts;
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->debounce_max = pdata->debounce_max ? : 1;
ts->debounce_tol = pdata->debounce_tol ? : 10;
goto err_free_mem;
}
- dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
+ dev_info(&spi->dev, "touchscreen + hwmon, irq %d\n", spi->irq);
- /* take a first sample, leaving nPENIRQ active; avoid
+ /* take a first sample, leaving nPENIRQ active and vREF off; 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
+ * use the other ADC lines a bit differently too
*/
if (ts->model == 7846) {
device_create_file(&spi->dev, &dev_attr_temp0);
device_create_file(&spi->dev, &dev_attr_temp1);
}
+ /* in1 == vBAT (7846), or a non-scaled ADC input */
if (ts->model != 7845)
- device_create_file(&spi->dev, &dev_attr_vbatt);
- device_create_file(&spi->dev, &dev_attr_vaux);
+ device_create_file(&spi->dev, &dev_attr_in1_input);
+ /* in0 == a non-scaled ADC input */
+ device_create_file(&spi->dev, &dev_attr_in0_input);
+ /* non-hwmon device attributes */
device_create_file(&spi->dev, &dev_attr_pen_down);
-
device_create_file(&spi->dev, &dev_attr_disable);
err = input_register_device(input_dev);
device_remove_file(&spi->dev, &dev_attr_temp0);
}
if (ts->model != 7845)
- device_remove_file(&spi->dev, &dev_attr_vbatt);
- device_remove_file(&spi->dev, &dev_attr_vaux);
+ device_remove_file(&spi->dev, &dev_attr_in1_input);
+ device_remove_file(&spi->dev, &dev_attr_in0_input);
free_irq(spi->irq, ts);
err_free_mem:
+ if (!IS_ERR(hwmon))
+ hwmon_device_unregister(hwmon);
input_free_device(input_dev);
kfree(ts);
return err;
{
struct ads7846 *ts = dev_get_drvdata(&spi->dev);
+ hwmon_device_unregister(ts->hwmon);
input_unregister_device(ts->input);
ads7846_suspend(spi, PMSG_SUSPEND);
device_remove_file(&spi->dev, &dev_attr_temp0);
}
if (ts->model != 7845)
- device_remove_file(&spi->dev, &dev_attr_vbatt);
- device_remove_file(&spi->dev, &dev_attr_vaux);
+ device_remove_file(&spi->dev, &dev_attr_in1_input);
+ device_remove_file(&spi->dev, &dev_attr_in0_input);
free_irq(ts->spi->irq, ts);
if (ts->irq_disabled)
return spi_register_driver(&ads7846_driver);
}
-module_init(ads7846_init);
+device_initcall(ads7846_init);
static void __exit ads7846_exit(void)
{
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