Input: ads7846 - be more compatible with the hwmon framework
- Hook up to hwmon
* show sensor attributes only if hwmon is present
* ... and the board's reference voltage is known
* otherwise be just a touchscreen
- Report voltages per hwmon convention
* measure in millivolts
* voltages are named in[0-8]_input (ugh)
* for 7846 chips, properly range-adjust vBATT/in1_input
Battery measurements help during recharge monitoring. On OSK/Mistral,
the measured voltage agreed with a multimeter to several decimal places.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index b18c63a..cd251ef 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -17,8 +17,9 @@
* 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>
@@ -69,7 +70,7 @@
u16 x;
u16 y;
u16 z1, z2;
- int ignore;
+ int ignore;
};
struct ads7846 {
@@ -77,7 +78,12 @@
char phys[32];
struct spi_device *spi;
+
+#if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
struct attribute_group *attr_group;
+ struct class_device *hwmon;
+#endif
+
u16 model;
u16 vref_delay_usecs;
u16 x_plate_ohms;
@@ -170,7 +176,12 @@
/*
* 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.
*/
+static unsigned vREF_mV;
+module_param(vREF_mV, uint, 0);
+MODULE_PARM_DESC(vREF_mV, "external vREF voltage, in milliVolts");
struct ser_req {
u8 ref_on;
@@ -198,50 +209,55 @@
struct ser_req *req = kzalloc(sizeof *req, GFP_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;
+ /* FIXME boards with ads7846 might use external vref instead ... */
+ use_internal = (ts->model == 7846);
- /*
- * 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;
+ /* 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;
+ /* 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);
- 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);
+ 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);
+ }
ts->irq_disabled = 1;
disable_irq(spi->irq);
@@ -261,25 +277,173 @@
return status ? status : sample;
}
-#define SHOW(name) static ssize_t \
+#if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
+
+#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.
+ * 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 *= 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 struct attribute *ads7846_attributes[] = {
+ &dev_attr_temp0.attr,
+ &dev_attr_temp1.attr,
+ &dev_attr_in0_input.attr,
+ &dev_attr_in1_input.attr,
+ NULL,
+};
+
+static struct attribute_group ads7846_attr_group = {
+ .attrs = ads7846_attributes,
+};
+
+static struct attribute *ads7843_attributes[] = {
+ &dev_attr_in0_input.attr,
+ &dev_attr_in1_input.attr,
+ NULL,
+};
+
+static struct attribute_group ads7843_attr_group = {
+ .attrs = ads7843_attributes,
+};
+
+static struct attribute *ads7845_attributes[] = {
+ &dev_attr_in0_input.attr,
+ NULL,
+};
+
+static struct attribute_group ads7845_attr_group = {
+ .attrs = ads7845_attributes,
+};
+
+static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
+{
+ struct class_device *hwmon;
+ int err;
+
+ /* hwmon sensors need a reference voltage */
+ switch (ts->model) {
+ case 7846:
+ if (!vREF_mV) {
+ dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
+ vREF_mV = 2500;
+ }
+ break;
+ case 7845:
+ case 7843:
+ if (!vREF_mV) {
+ dev_warn(&spi->dev,
+ "external vREF for ADS%d not specified\n",
+ ts->model);
+ return 0;
+ }
+ break;
+ }
+
+ /* different chips have different sensor groups */
+ switch (ts->model) {
+ case 7846:
+ ts->attr_group = &ads7846_attr_group;
+ break;
+ case 7845:
+ ts->attr_group = &ads7845_attr_group;
+ break;
+ case 7843:
+ ts->attr_group = &ads7843_attr_group;
+ break;
+ default:
+ dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model);
+ return 0;
+ }
+
+ err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
+ if (err)
+ return err;
+
+ hwmon = hwmon_device_register(&spi->dev);
+ if (IS_ERR(hwmon)) {
+ sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
+ return PTR_ERR(hwmon);
+ }
+
+ ts->hwmon = hwmon;
+ return 0;
+}
+
+static void ads784x_hwmon_unregister(struct spi_device *spi,
+ struct ads7846 *ts)
+{
+ if (ts->hwmon) {
+ sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
+ 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 int is_pen_down(struct device *dev)
{
- struct ads7846 *ts = dev_get_drvdata(dev);
+ struct ads7846 *ts = dev_get_drvdata(dev);
return ts->pendown;
}
@@ -323,46 +487,14 @@
static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
-static struct attribute *ads7846_attributes[] = {
- &dev_attr_temp0.attr,
- &dev_attr_temp1.attr,
- &dev_attr_vbatt.attr,
- &dev_attr_vaux.attr,
+static struct attribute *ads784x_attributes[] = {
&dev_attr_pen_down.attr,
&dev_attr_disable.attr,
NULL,
};
-static struct attribute_group ads7846_attr_group = {
- .attrs = ads7846_attributes,
-};
-
-/*
- * ads7843/7845 don't have temperature sensors, and
- * use the other sensors a bit differently too
- */
-
-static struct attribute *ads7843_attributes[] = {
- &dev_attr_vbatt.attr,
- &dev_attr_vaux.attr,
- &dev_attr_pen_down.attr,
- &dev_attr_disable.attr,
- NULL,
-};
-
-static struct attribute_group ads7843_attr_group = {
- .attrs = ads7843_attributes,
-};
-
-static struct attribute *ads7845_attributes[] = {
- &dev_attr_vaux.attr,
- &dev_attr_pen_down.attr,
- &dev_attr_disable.attr,
- NULL,
-};
-
-static struct attribute_group ads7845_attr_group = {
- .attrs = ads7845_attributes,
+static struct attribute_group ads784x_attr_group = {
+ .attrs = ads784x_attributes,
};
/*--------------------------------------------------------------------------*/
@@ -886,28 +1018,21 @@
goto err_cleanup_filter;
}
+ 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; 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);
- switch (ts->model) {
- case 7846:
- ts->attr_group = &ads7846_attr_group;
- break;
- case 7845:
- ts->attr_group = &ads7845_attr_group;
- break;
- default:
- ts->attr_group = &ads7843_attr_group;
- break;
- }
- err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
+ err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
if (err)
- goto err_free_irq;
+ goto err_remove_hwmon;
err = input_register_device(input_dev);
if (err)
@@ -916,7 +1041,9 @@
return 0;
err_remove_attr_group:
- sysfs_remove_group(&spi->dev.kobj, ts->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_cleanup_filter:
@@ -932,11 +1059,12 @@
{
struct ads7846 *ts = dev_get_drvdata(&spi->dev);
+ ads784x_hwmon_unregister(spi, ts);
input_unregister_device(ts->input);
ads7846_suspend(spi, PMSG_SUSPEND);
- sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
+ sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
free_irq(ts->spi->irq, ts);
/* suspend left the IRQ disabled */