mirror of
https://github.com/Ysurac/openmptcprouter.git
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192 lines
5 KiB
Diff
192 lines
5 KiB
Diff
From d9bfc095253338bbbfddbd15681c64593219f91e Mon Sep 17 00:00:00 2001
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From: Dave Stevenson <dave.stevenson@raspberrypi.com>
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Date: Thu, 14 Oct 2021 11:09:18 +0100
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Subject: [PATCH 540/828] drivers/gpio: Add a driver that wraps the PWM API as
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a GPIO controller
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For cases where spare PWM outputs are available, but are desired
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to be addressed a standard outputs instead.
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Wraps a PWM channel as a new GPIO chip with the one output.
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Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
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---
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drivers/gpio/Kconfig | 8 +++
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drivers/gpio/Makefile | 1 +
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drivers/gpio/gpio-pwm.c | 144 ++++++++++++++++++++++++++++++++++++++++
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3 files changed, 153 insertions(+)
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create mode 100644 drivers/gpio/gpio-pwm.c
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--- a/drivers/gpio/Kconfig
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+++ b/drivers/gpio/Kconfig
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@@ -485,6 +485,14 @@ config GPIO_PMIC_EIC_SPRD
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help
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Say yes here to support Spreadtrum PMIC EIC device.
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+config GPIO_PWM
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+ tristate "PWM chip GPIO"
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+ depends on OF_GPIO
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+ depends on PWM
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+ help
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+ Turn on support for exposing a PWM chip as a GPIO
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+ driver.
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+
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config GPIO_PXA
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bool "PXA GPIO support"
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depends on ARCH_PXA || ARCH_MMP || COMPILE_TEST
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--- a/drivers/gpio/Makefile
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+++ b/drivers/gpio/Makefile
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@@ -122,6 +122,7 @@ obj-$(CONFIG_GPIO_PCI_IDIO_16) += gpio-
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obj-$(CONFIG_GPIO_PISOSR) += gpio-pisosr.o
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obj-$(CONFIG_GPIO_PL061) += gpio-pl061.o
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obj-$(CONFIG_GPIO_PMIC_EIC_SPRD) += gpio-pmic-eic-sprd.o
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+obj-$(CONFIG_GPIO_PWM) += gpio-pwm.o
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obj-$(CONFIG_GPIO_PXA) += gpio-pxa.o
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obj-$(CONFIG_GPIO_RASPBERRYPI_EXP) += gpio-raspberrypi-exp.o
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obj-$(CONFIG_GPIO_RC5T583) += gpio-rc5t583.o
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--- /dev/null
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+++ b/drivers/gpio/gpio-pwm.c
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@@ -0,0 +1,144 @@
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+// SPDX-License-Identifier: GPL-2.0+
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+/*
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+ * GPIO driver wrapping PWM API
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+ *
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+ * PWM 0% and PWM 100% are equivalent to digital GPIO
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+ * outputs, and there are times where it is useful to use
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+ * PWM outputs as straight GPIOs (eg outputs of NXP PCA9685
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+ * I2C PWM chip). This driver wraps the PWM API as a GPIO
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+ * controller.
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+ *
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+ * Copyright (C) 2021 Raspberry Pi (Trading) Ltd.
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+ */
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+
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+#include <linux/err.h>
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+#include <linux/gpio/driver.h>
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+#include <linux/module.h>
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+#include <linux/platform_device.h>
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+#include <linux/pwm.h>
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+
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+struct pwm_gpio {
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+ struct gpio_chip gc;
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+ struct pwm_device **pwm;
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+};
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+
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+static int pwm_gpio_get_direction(struct gpio_chip *gc, unsigned int off)
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+{
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+ return GPIO_LINE_DIRECTION_OUT;
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+}
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+
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+static void pwm_gpio_set(struct gpio_chip *gc, unsigned int off, int val)
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+{
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+ struct pwm_gpio *pwm_gpio = gpiochip_get_data(gc);
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+ struct pwm_state state;
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+
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+ pwm_get_state(pwm_gpio->pwm[off], &state);
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+ state.duty_cycle = val ? state.period : 0;
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+ pwm_apply_state(pwm_gpio->pwm[off], &state);
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+}
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+
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+static int pwm_gpio_parse_dt(struct pwm_gpio *pwm_gpio,
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+ struct device *dev)
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+{
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+ struct device_node *node = dev->of_node;
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+ struct pwm_state state;
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+ int ret = 0, i, num_gpios;
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+ const char *pwm_name;
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+
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+ if (!node)
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+ return -ENODEV;
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+
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+ num_gpios = of_property_count_strings(node, "pwm-names");
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+ if (num_gpios <= 0)
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+ return 0;
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+
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+ pwm_gpio->pwm = devm_kzalloc(dev,
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+ sizeof(*pwm_gpio->pwm) * num_gpios,
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+ GFP_KERNEL);
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+ if (!pwm_gpio->pwm)
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+ return -ENOMEM;
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+
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+ for (i = 0; i < num_gpios; i++) {
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+ ret = of_property_read_string_index(node, "pwm-names", i,
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+ &pwm_name);
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+ if (ret) {
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+ dev_err(dev, "unable to get pwm device index %d, name %s",
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+ i, pwm_name);
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+ goto error;
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+ }
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+
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+ pwm_gpio->pwm[i] = devm_pwm_get(dev, pwm_name);
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+ if (IS_ERR(pwm_gpio->pwm[i])) {
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+ ret = PTR_ERR(pwm_gpio->pwm[i]);
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+ if (ret != -EPROBE_DEFER)
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+ dev_err(dev, "unable to request PWM\n");
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+ goto error;
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+ }
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+
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+ /* Sync up PWM state. */
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+ pwm_init_state(pwm_gpio->pwm[i], &state);
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+
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+ state.duty_cycle = 0;
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+ pwm_apply_state(pwm_gpio->pwm[i], &state);
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+ }
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+
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+ pwm_gpio->gc.ngpio = num_gpios;
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+
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+error:
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+ return ret;
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+}
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+
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+static int pwm_gpio_probe(struct platform_device *pdev)
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+{
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+ struct device *dev = &pdev->dev;
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+ struct pwm_gpio *pwm_gpio;
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+ int ret;
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+
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+ pwm_gpio = devm_kzalloc(dev, sizeof(*pwm_gpio), GFP_KERNEL);
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+ if (!pwm_gpio)
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+ return -ENOMEM;
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+
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+ pwm_gpio->gc.parent = dev;
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+ pwm_gpio->gc.label = "pwm-gpio";
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+ pwm_gpio->gc.owner = THIS_MODULE;
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+ pwm_gpio->gc.of_node = dev->of_node;
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+ pwm_gpio->gc.base = -1;
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+
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+ pwm_gpio->gc.get_direction = pwm_gpio_get_direction;
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+ pwm_gpio->gc.set = pwm_gpio_set;
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+ pwm_gpio->gc.can_sleep = true;
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+
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+ ret = pwm_gpio_parse_dt(pwm_gpio, dev);
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+ if (ret)
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+ return ret;
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+
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+ if (!pwm_gpio->gc.ngpio)
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+ return 0;
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+
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+ return devm_gpiochip_add_data(dev, &pwm_gpio->gc, pwm_gpio);
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+}
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+
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+static int pwm_gpio_remove(struct platform_device *pdev)
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+{
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+ return 0;
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+}
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+
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+static const struct of_device_id pwm_gpio_of_match[] = {
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+ { .compatible = "pwm-gpio" },
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+ { }
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+};
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+MODULE_DEVICE_TABLE(of, pwm_gpio_of_match);
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+
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+static struct platform_driver pwm_gpio_driver = {
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+ .driver = {
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+ .name = "pwm-gpio",
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+ .of_match_table = of_match_ptr(pwm_gpio_of_match),
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+ },
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+ .probe = pwm_gpio_probe,
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+ .remove = pwm_gpio_remove,
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+};
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+module_platform_driver(pwm_gpio_driver);
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+
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+MODULE_LICENSE("GPL");
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+MODULE_AUTHOR("Dave Stevenson <dave.stevenson@raspberrypi.com>");
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+MODULE_DESCRIPTION("PWM GPIO driver");
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