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leds: pca955x: add GPIO support 

The PCA955x family of chips are I2C LED blinkers whose pins not used
to control LEDs can be used as general purpose I/Os (GPIOs).

The following adds such a support by defining different operation
modes for the pins (See bindings documentation for more details). The
pca955x driver is then extended with a gpio_chip when some of pins are
operating as GPIOs. The default operating mode is to behave as a LED.

The GPIO support is conditioned by CONFIG_LEDS_PCA955X_GPIO.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
This commit is contained in:
Cédric Le Goater 2017-08-08 15:42:39 +02:00 committed by Jacek Anaszewski
parent 91940bb4ca
commit 561099a1a2
3 changed files with 147 additions and 17 deletions
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11
drivers/leds/Kconfig
View File

@ -377,6 +377,17 @@ config LEDS_PCA955X
LED driver chips accessed via the I2C bus. Supported
devices include PCA9550, PCA9551, PCA9552, and PCA9553.
config LEDS_PCA955X_GPIO
bool "Enable GPIO support for PCA955X"
depends on LEDS_PCA955X
depends on GPIOLIB
help
Allow unused pins on PCA955X to be used as gpio.
To use a pin as gpio the pin type should be set to
PCA955X_TYPE_GPIO in the device tree.
config LEDS_PCA963X
tristate "LED support for PCA963x I2C chip"
depends on LEDS_CLASS

137
drivers/leds/leds-pca955x.c
View File

@ -53,6 +53,8 @@
#include <linux/slab.h>
#include <linux/string.h>
#include <dt-bindings/leds/leds-pca955x.h>
/* LED select registers determine the source that drives LED outputs */
#define PCA955X_LS_LED_ON 0x0 /* Output LOW */
#define PCA955X_LS_LED_OFF 0x1 /* Output HI-Z */
@ -118,6 +120,9 @@ struct pca955x {
struct pca955x_led *leds;
struct pca955x_chipdef *chipdef;
struct i2c_client *client;
#ifdef CONFIG_LEDS_PCA955X_GPIO
struct gpio_chip gpio;
#endif
};
struct pca955x_led {
@ -125,6 +130,7 @@ struct pca955x_led {
struct led_classdev led_cdev;
int led_num; /* 0 .. 15 potentially */
char name[32];
u32 type;
const char *default_trigger;
};
@ -259,6 +265,65 @@ static int pca955x_led_set(struct led_classdev *led_cdev,
return 0;
}
#ifdef CONFIG_LEDS_PCA955X_GPIO
/*
* Read the INPUT register, which contains the state of LEDs.
*/
static u8 pca955x_read_input(struct i2c_client *client, int n)
{
return (u8)i2c_smbus_read_byte_data(client, n);
}
static int pca955x_gpio_request_pin(struct gpio_chip *gc, unsigned int offset)
{
struct pca955x *pca955x = gpiochip_get_data(gc);
struct pca955x_led *led = &pca955x->leds[offset];
if (led->type == PCA955X_TYPE_GPIO)
return 0;
return -EBUSY;
}
static void pca955x_gpio_set_value(struct gpio_chip *gc, unsigned int offset,
int val)
{
struct pca955x *pca955x = gpiochip_get_data(gc);
struct pca955x_led *led = &pca955x->leds[offset];
if (val)
pca955x_led_set(&led->led_cdev, LED_FULL);
else
pca955x_led_set(&led->led_cdev, LED_OFF);
}
static int pca955x_gpio_get_value(struct gpio_chip *gc, unsigned int offset)
{
struct pca955x *pca955x = gpiochip_get_data(gc);
struct pca955x_led *led = &pca955x->leds[offset];
u8 reg = pca955x_read_input(pca955x->client, led->led_num / 8);
return !!(reg & (1 << (led->led_num % 8)));
}
static int pca955x_gpio_direction_input(struct gpio_chip *gc,
unsigned int offset)
{
/* To use as input ensure pin is not driven */
pca955x_gpio_set_value(gc, offset, 0);
return 0;
}
static int pca955x_gpio_direction_output(struct gpio_chip *gc,
unsigned int offset, int val)
{
pca955x_gpio_set_value(gc, offset, val);
return 0;
}
#endif /* CONFIG_LEDS_PCA955X_GPIO */
#if IS_ENABLED(CONFIG_OF)
static struct pca955x_platform_data *
pca955x_pdata_of_init(struct i2c_client *client, struct pca955x_chipdef *chip)
@ -297,6 +362,8 @@ pca955x_pdata_of_init(struct i2c_client *client, struct pca955x_chipdef *chip)
snprintf(pdata->leds[reg].name, sizeof(pdata->leds[reg].name),
"%s", name);
pdata->leds[reg].type = PCA955X_TYPE_LED;
of_property_read_u32(child, "type", &pdata->leds[reg].type);
of_property_read_string(child, "linux,default-trigger",
&pdata->leds[reg].default_trigger);
}
@ -332,6 +399,7 @@ static int pca955x_probe(struct i2c_client *client,
struct i2c_adapter *adapter;
int i, err;
struct pca955x_platform_data *pdata;
int ngpios = 0;
if (id) {
chip = &pca955x_chipdefs[id->driver_data];
@ -392,9 +460,19 @@ static int pca955x_probe(struct i2c_client *client,
pca955x_led = &pca955x->leds[i];
pca955x_led->led_num = i;
pca955x_led->pca955x = pca955x;
pca955x_led->type = pdata->leds[i].type;
/* Platform data can specify LED names and default triggers */
if (pdata) {
switch (pca955x_led->type) {
case PCA955X_TYPE_NONE:
break;
case PCA955X_TYPE_GPIO:
ngpios++;
break;
case PCA955X_TYPE_LED:
/*
* Platform data can specify LED names and
* default triggers
*/
if (pdata->leds[i].name)
snprintf(pca955x_led->name,
sizeof(pca955x_led->name), "pca955x:%s",
@ -402,24 +480,21 @@ static int pca955x_probe(struct i2c_client *client,
if (pdata->leds[i].default_trigger)
pca955x_led->led_cdev.default_trigger =
pdata->leds[i].default_trigger;
} else {
snprintf(pca955x_led->name, sizeof(pca955x_led->name),
"pca955x:%d", i);
pca955x_led->led_cdev.name = pca955x_led->name;
pca955x_led->led_cdev.brightness_set_blocking =
pca955x_led_set;
err = devm_led_classdev_register(&client->dev,
&pca955x_led->led_cdev);
if (err)
return err;
/* Turn off LED */
pca955x_led_set(&pca955x_led->led_cdev, LED_OFF);
}
pca955x_led->led_cdev.name = pca955x_led->name;
pca955x_led->led_cdev.brightness_set_blocking = pca955x_led_set;
err = devm_led_classdev_register(&client->dev,
&pca955x_led->led_cdev);
if (err)
return err;
}
/* Turn off LEDs */
for (i = 0; i < pca95xx_num_led_regs(chip->bits); i++)
pca955x_write_ls(client, i, 0x55);
/* PWM0 is used for half brightness or 50% duty cycle */
pca955x_write_pwm(client, 0, 255-LED_HALF);
@ -430,6 +505,34 @@ static int pca955x_probe(struct i2c_client *client,
pca955x_write_psc(client, 0, 0);
pca955x_write_psc(client, 1, 0);
#ifdef CONFIG_LEDS_PCA955X_GPIO
if (ngpios) {
pca955x->gpio.label = "gpio-pca955x";
pca955x->gpio.direction_input = pca955x_gpio_direction_input;
pca955x->gpio.direction_output = pca955x_gpio_direction_output;
pca955x->gpio.set = pca955x_gpio_set_value;
pca955x->gpio.get = pca955x_gpio_get_value;
pca955x->gpio.request = pca955x_gpio_request_pin;
pca955x->gpio.can_sleep = 1;
pca955x->gpio.base = -1;
pca955x->gpio.ngpio = ngpios;
pca955x->gpio.parent = &client->dev;
pca955x->gpio.owner = THIS_MODULE;
err = devm_gpiochip_add_data(&client->dev, &pca955x->gpio,
pca955x);
if (err) {
/* Use data->gpio.dev as a flag for freeing gpiochip */
pca955x->gpio.parent = NULL;
dev_warn(&client->dev, "could not add gpiochip\n");
return err;
}
dev_info(&client->dev, "gpios %i...%i\n",
pca955x->gpio.base, pca955x->gpio.base +
pca955x->gpio.ngpio - 1);
}
#endif
return 0;
}

16
include/dt-bindings/leds/leds-pca955x.h Normal file
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@ -0,0 +1,16 @@
/*
* This header provides constants for pca955x LED bindings.
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#ifndef _DT_BINDINGS_LEDS_PCA955X_H
#define _DT_BINDINGS_LEDS_PCA955X_H
#define PCA955X_TYPE_NONE 0
#define PCA955X_TYPE_LED 1
#define PCA955X_TYPE_GPIO 2
#endif /* _DT_BINDINGS_LEDS_PCA955X_H */