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Commit 659cb49d authored by David Brownell's avatar David Brownell Committed by Tony Lindgren
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[PATCH] ARM: OMAP: ads7846 updates, mostly for hwmon 

The ads784x chips include not just touchscreen sensors but also temperature
and voltage sensors, which are traditional hwmon fodder.

 - Register with the hwmon framework
    * hwmon needs to use subsys_init() so it's available early enough
 - Adopt hwmon convention for presenting voltages:
    * Report voltages in millivolts
    * Attribute names are "in[0-8]_input" (meaningless, ugh)
 - Be more accurate for the hwmon values:
    * vBATT gets range-adjusted
    * Discard the extra bit sent before the sample.

Battery measurements help during battery recharge monitoring.  On OSK/Mistral,
the measured voltage agreed with a multimeter until the fourth decimal place.

NOTE:  this version is only for the OMAP tree, which has some byteswap bugs
(and other changes) that are not found in the upstream kernels.
Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: default avatarTony Lindgren <tony@atomide.com>
parent 0b50a217
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Showing with 126 additions and 64 deletions
drivers/hwmon/hwmon.c
View file @ 659cb49d
......@@ -101,7 +101,7 @@ static void __exit hwmon_exit(void)
class_destroy(hwmon_class);
}
module_init(hwmon_init);
subsys_initcall(hwmon_init);
module_exit(hwmon_exit);
EXPORT_SYMBOL_GPL(hwmon_device_register);
......
drivers/input/touchscreen/Kconfig
View file @ 659cb49d
......@@ -14,10 +14,13 @@ if INPUT_TOUCHSCREEN
config TOUCHSCREEN_ADS7846
tristate "ADS 7846 based touchscreens"
depends on SPI_MASTER
select HWMON
help
Say Y here if you have a touchscreen interface using the
ADS7846 controller, and your board-specific initialization
code includes that in its table of SPI devices.
code includes that in its table of SPI devices. You will
also get hwmon interfaces for the temperature and voltage
sensors this chip provides.
If unsure, say N (but it's safe to say "Y").
......
drivers/input/touchscreen/ads7846.c
View file @ 659cb49d
......@@ -16,8 +16,9 @@
* 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>
......@@ -36,13 +37,9 @@
/*
* 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
......@@ -78,6 +75,7 @@ struct ads7846 {
char phys[32];
struct spi_device *spi;
struct class_device *hwmon;
u16 model;
u16 vref_delay_usecs;
u16 x_plate_ohms;
......@@ -164,7 +162,12 @@ struct ads7846 {
/*
* 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;
......@@ -186,50 +189,55 @@ static int ads7846_read12_ser(struct device *dev, unsigned command)
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);
......@@ -237,28 +245,70 @@ static int ads7846_read12_ser(struct device *dev, unsigned command)
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)
{
......@@ -326,13 +376,13 @@ static void ads7846_rx(void *ads)
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)
......@@ -560,6 +610,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
{
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;
......@@ -585,12 +636,14 @@ static int __devinit ads7846_probe(struct spi_device *spi)
/* 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;
}
......@@ -600,6 +653,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
ts->spi = spi;
ts->input = input_dev;
ts->hwmon = hwmon;
init_timer(&ts->timer);
ts->timer.data = (unsigned long) ts;
......@@ -737,27 +791,29 @@ static int __devinit ads7846_probe(struct spi_device *spi)
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);
......@@ -774,11 +830,13 @@ static int __devinit ads7846_probe(struct spi_device *spi)
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;
......@@ -788,6 +846,7 @@ static int __devexit ads7846_remove(struct spi_device *spi)
{
struct ads7846 *ts = dev_get_drvdata(&spi->dev);
hwmon_device_unregister(ts->hwmon);
input_unregister_device(ts->input);
ads7846_suspend(spi, PMSG_SUSPEND);
......@@ -799,8 +858,8 @@ static int __devexit ads7846_remove(struct spi_device *spi)
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)
......@@ -853,7 +912,7 @@ static int __init ads7846_init(void)
return spi_register_driver(&ads7846_driver);
}
module_init(ads7846_init);
device_initcall(ads7846_init);
static void __exit ads7846_exit(void)
{
......
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