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144 lines
3.3 KiB
144 lines
3.3 KiB
// 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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#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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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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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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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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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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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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if (!node) |
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return -ENODEV; |
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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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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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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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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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/* Sync up PWM state. */ |
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pwm_init_state(pwm_gpio->pwm[i], &state); |
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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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pwm_gpio->gc.ngpio = num_gpios; |
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error: |
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return ret; |
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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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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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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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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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ret = pwm_gpio_parse_dt(pwm_gpio, dev); |
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if (ret) |
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return ret; |
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if (!pwm_gpio->gc.ngpio) |
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return 0; |
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return devm_gpiochip_add_data(dev, &pwm_gpio->gc, pwm_gpio); |
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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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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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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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MODULE_LICENSE("GPL"); |
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MODULE_AUTHOR("Dave Stevenson <[email protected]>"); |
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MODULE_DESCRIPTION("PWM GPIO driver");
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