Hi Dmitry I am curious about how reset gpio works and I think the reset gpio at low level after elants_i2c_power_on(), So that the controller won't response anyway, please see below my question and correct me if I am wrong. > -----Original Message----- > From: Dmitry Torokhov [mailto:dtor@xxxxxxxxxxxx] > Sent: Thursday, August 06, 2015 2:54 AM > To: linux-input@xxxxxxxxxxxxxxx > Cc: Rob Herring; Mark Rutland; Benson Leung; Duson Lin; Scott Liu; James > Chen; devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > linux-input@xxxxxxxxxxxxxxx > Subject: [PATCH] Input: elants_i2c - wire up regulator support > > Elan touchscreen controllers use two power supplies, vcc33 and vccio, and > we need to enable them before trying to access the device. On X86 firmware > usually does this, but on ARM it is usually left to the kernel. > > Signed-off-by: Dmitry Torokhov <dtor@xxxxxxxxxxxx> > Reviewed-by: Benson Leung <bleung@xxxxxxxxxxxx> > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> > --- > .../devicetree/bindings/input/elants_i2c.txt | 3 + > drivers/input/touchscreen/elants_i2c.c | 184 > ++++++++++++++++++--- > 2 files changed, 165 insertions(+), 22 deletions(-) > > diff --git a/Documentation/devicetree/bindings/input/elants_i2c.txt > b/Documentation/devicetree/bindings/input/elants_i2c.txt > index a765232..8a71038 100644 > --- a/Documentation/devicetree/bindings/input/elants_i2c.txt > +++ b/Documentation/devicetree/bindings/input/elants_i2c.txt > @@ -13,6 +13,9 @@ Optional properties: > - pinctrl-names: should be "default" (see pinctrl binding [1]). > - pinctrl-0: a phandle pointing to the pin settings for the device (see > pinctrl binding [1]). > +- reset-gpios: reset gpio the chip is connected to. > +- vcc33-supply: a phandle for the regulator supplying 3.3V power. > +- vccio-supply: a phandle for the regulator supplying IO power. > > [0]: Documentation/devicetree/bindings/interrupt-controller/interrupts.txt > [1]: Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt > diff --git a/drivers/input/touchscreen/elants_i2c.c > b/drivers/input/touchscreen/elants_i2c.c > index 42e43f1..1912265 100644 > --- a/drivers/input/touchscreen/elants_i2c.c > +++ b/drivers/input/touchscreen/elants_i2c.c > @@ -38,6 +38,8 @@ > #include <linux/input/mt.h> > #include <linux/acpi.h> > #include <linux/of.h> > +#include <linux/gpio/consumer.h> > +#include <linux/regulator/consumer.h> > #include <asm/unaligned.h> > > /* Device, Driver information */ > @@ -102,6 +104,9 @@ > /* calibration timeout definition */ > #define ELAN_CALI_TIMEOUT_MSEC 10000 > > +#define ELAN_POWERON_DELAY_USEC 500 > +#define ELAN_RESET_DELAY_MSEC 20 > + > enum elants_state { > ELAN_STATE_NORMAL, > ELAN_WAIT_QUEUE_HEADER, > @@ -118,6 +123,10 @@ struct elants_data { > struct i2c_client *client; > struct input_dev *input; > > + struct regulator *vcc33; > + struct regulator *vccio; > + struct gpio_desc *reset_gpio; > + > u16 fw_version; > u8 test_version; > u8 solution_version; > @@ -141,6 +150,7 @@ struct elants_data { > u8 buf[MAX_PACKET_SIZE]; > > bool wake_irq_enabled; > + bool keep_power_in_suspend; > }; > > static int elants_i2c_send(struct i2c_client *client, @@ -1058,6 +1068,67 > @@ static void elants_i2c_remove_sysfs_group(void *_data) > sysfs_remove_group(&ts->client->dev.kobj, > &elants_attribute_group); } > > +static int elants_i2c_power_on(struct elants_data *ts) { > + int error; > + > + /* > + * If we do not have reset gpio assume platform firmware > + * controls regulators and does power them on for us. > + */ > + if (IS_ERR_OR_NULL(ts->reset_gpio)) > + return 0; > + > + gpiod_set_value_cansleep(ts->reset_gpio, 1); > + > + error = regulator_enable(ts->vcc33); > + if (error) { > + dev_err(&ts->client->dev, > + "failed to enable vcc33 regulator: %d\n", > + error); > + goto release_reset_gpio; > + } > + > + error = regulator_enable(ts->vccio); > + if (error) { > + dev_err(&ts->client->dev, > + "failed to enable vccio regulator: %d\n", > + error); > + regulator_disable(ts->vcc33); > + goto release_reset_gpio; > + } > + > + /* > + * We need to wait a bit after powering on controller before > + * we are allowed to release reset GPIO. > + */ > + udelay(ELAN_POWERON_DELAY_USEC); > + > +release_reset_gpio: > + gpiod_set_value_cansleep(ts->reset_gpio, 0); > + if (error) > + return error; > + > + msleep(ELAN_RESET_DELAY_MSEC); > + > + return 0; > +} > + > +static void elants_i2c_power_off(void *_data) { > + struct elants_data *ts = _data; > + > + if (!IS_ERR_OR_NULL(ts->reset_gpio)) { > + /* > + * Activate reset gpio to prevent leakage through the > + * pin once we shut off power to the controller. > + */ > + gpiod_set_value_cansleep(ts->reset_gpio, 1); > + regulator_disable(ts->vccio); > + regulator_disable(ts->vcc33); > + } > +} > + > static int elants_i2c_probe(struct i2c_client *client, > const struct i2c_device_id *id) > { > @@ -1072,13 +1143,6 @@ static int elants_i2c_probe(struct i2c_client > *client, > return -ENXIO; > } > > - /* Make sure there is something at this address */ > - if (i2c_smbus_xfer(client->adapter, client->addr, 0, > - I2C_SMBUS_READ, 0, I2C_SMBUS_BYTE, &dummy) < 0) { > - dev_err(&client->dev, "nothing at this address\n"); > - return -ENXIO; > - } > - > ts = devm_kzalloc(&client->dev, sizeof(struct elants_data), > GFP_KERNEL); > if (!ts) > return -ENOMEM; > @@ -1089,6 +1153,70 @@ static int elants_i2c_probe(struct i2c_client > *client, > ts->client = client; > i2c_set_clientdata(client, ts); > > + ts->vcc33 = devm_regulator_get(&client->dev, "vcc33"); > + if (IS_ERR(ts->vcc33)) { > + error = PTR_ERR(ts->vcc33); > + if (error != -EPROBE_DEFER) > + dev_err(&client->dev, > + "Failed to get 'vcc33' regulator: %d\n", > + error); > + return error; > + } > + > + ts->vccio = devm_regulator_get(&client->dev, "vccio"); > + if (IS_ERR(ts->vccio)) { > + error = PTR_ERR(ts->vccio); > + if (error != -EPROBE_DEFER) > + dev_err(&client->dev, > + "Failed to get 'vccio' regulator: %d\n", > + error); > + return error; > + } > + > + ts->reset_gpio = devm_gpiod_get(&client->dev, "reset"); > + if (IS_ERR(ts->reset_gpio)) { > + error = PTR_ERR(ts->reset_gpio); > + > + if (error == -EPROBE_DEFER) > + return error; > + > + if (error != -ENOENT && error != -ENOSYS) { > + dev_err(&client->dev, > + "failed to get reset gpio: %d\n", > + error); > + return error; > + } > + > + ts->keep_power_in_suspend = true; > + } else { > + error = gpiod_direction_output(ts->reset_gpio, 0); Does it mean to reset our controller? (reset gpio pull low). > + if (error) { > + dev_err(&client->dev, > + "failed to configure reset gpio as output: %d\n", > + error); > + return error; > + } > + } > + > + error = elants_i2c_power_on(ts); If reset gpio is at low, controller won't response initialize flow. I am curious that does reset pin be at low level after elants_i2c_power_on(ts)? Thanks, Scott > + if (error) > + return error; > + > + error = devm_add_action(&client->dev, elants_i2c_power_off, ts); > + if (error) { > + dev_err(&client->dev, > + "failed to install power off action: %d\n", error); > + elants_i2c_power_off(ts); > + return error; > + } > + > + /* Make sure there is something at this address */ > + if (i2c_smbus_xfer(client->adapter, client->addr, 0, > + I2C_SMBUS_READ, 0, I2C_SMBUS_BYTE, &dummy) < 0) { > + dev_err(&client->dev, "nothing at this address\n"); > + return -ENXIO; > + } > + > error = elants_i2c_initialize(ts); > if (error) { > dev_err(&client->dev, "failed to initialize: %d\n", error); @@ > -1196,17 +1324,23 @@ static int __maybe_unused elants_i2c_suspend(struct > device *dev) > > disable_irq(client->irq); > > - for (retry_cnt = 0; retry_cnt < MAX_RETRIES; retry_cnt++) { > - error = elants_i2c_send(client, set_sleep_cmd, > - sizeof(set_sleep_cmd)); > - if (!error) > - break; > + if (device_may_wakeup(dev) || ts->keep_power_in_suspend) { > + for (retry_cnt = 0; retry_cnt < MAX_RETRIES; retry_cnt++) { > + error = elants_i2c_send(client, set_sleep_cmd, > + sizeof(set_sleep_cmd)); > + if (!error) > + break; > > - dev_err(&client->dev, "suspend command failed: %d\n", error); > - } > + dev_err(&client->dev, > + "suspend command failed: %d\n", error); > + } > > - if (device_may_wakeup(dev)) > - ts->wake_irq_enabled = (enable_irq_wake(client->irq) == 0); > + if (device_may_wakeup(dev)) > + ts->wake_irq_enabled = > + (enable_irq_wake(client->irq) == 0); > + } else { > + elants_i2c_power_off(ts); > + } > > return 0; > } > @@ -1222,13 +1356,19 @@ static int __maybe_unused > elants_i2c_resume(struct device *dev) > if (device_may_wakeup(dev) && ts->wake_irq_enabled) > disable_irq_wake(client->irq); > > - for (retry_cnt = 0; retry_cnt < MAX_RETRIES; retry_cnt++) { > - error = elants_i2c_send(client, set_active_cmd, > - sizeof(set_active_cmd)); > - if (!error) > - break; > + if (ts->keep_power_in_suspend) { > + for (retry_cnt = 0; retry_cnt < MAX_RETRIES; retry_cnt++) { > + error = elants_i2c_send(client, set_active_cmd, > + sizeof(set_active_cmd)); > + if (!error) > + break; > > - dev_err(&client->dev, "resume command failed: %d\n", error); > + dev_err(&client->dev, > + "resume command failed: %d\n", error); > + } > + } else { > + elants_i2c_power_on(ts); > + elants_i2c_initialize(ts); > } > > ts->state = ELAN_STATE_NORMAL; > -- > 2.5.0.rc2.392.g76e840b > > > -- > Dmitry -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
