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![Stefan Wahren](/assets/img/avatar_default.png)
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com> Reviewed-by: Eric Anholt <eric@anholt.net> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
211 lines
5 KiB
C
211 lines
5 KiB
C
/*
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* Copyright 2014 Bart Tanghe <bart.tanghe@thomasmore.be>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2.
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*/
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#include <linux/clk.h>
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#include <linux/err.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/platform_device.h>
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#include <linux/pwm.h>
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#define PWM_CONTROL 0x000
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#define PWM_CONTROL_SHIFT(x) ((x) * 8)
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#define PWM_CONTROL_MASK 0xff
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#define PWM_MODE 0x80 /* set timer in PWM mode */
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#define PWM_ENABLE (1 << 0)
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#define PWM_POLARITY (1 << 4)
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#define PERIOD(x) (((x) * 0x10) + 0x10)
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#define DUTY(x) (((x) * 0x10) + 0x14)
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#define MIN_PERIOD 108 /* 9.2 MHz max. PWM clock */
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struct bcm2835_pwm {
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struct pwm_chip chip;
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struct device *dev;
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void __iomem *base;
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struct clk *clk;
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};
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static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip)
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{
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return container_of(chip, struct bcm2835_pwm, chip);
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}
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static int bcm2835_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
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u32 value;
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value = readl(pc->base + PWM_CONTROL);
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value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
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value |= (PWM_MODE << PWM_CONTROL_SHIFT(pwm->hwpwm));
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writel(value, pc->base + PWM_CONTROL);
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return 0;
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}
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static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
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u32 value;
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value = readl(pc->base + PWM_CONTROL);
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value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
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writel(value, pc->base + PWM_CONTROL);
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}
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static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
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int duty_ns, int period_ns)
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{
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struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
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unsigned long rate = clk_get_rate(pc->clk);
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unsigned long scaler;
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if (!rate) {
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dev_err(pc->dev, "failed to get clock rate\n");
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return -EINVAL;
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}
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scaler = NSEC_PER_SEC / rate;
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if (period_ns <= MIN_PERIOD) {
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dev_err(pc->dev, "period %d not supported, minimum %d\n",
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period_ns, MIN_PERIOD);
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return -EINVAL;
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}
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writel(duty_ns / scaler, pc->base + DUTY(pwm->hwpwm));
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writel(period_ns / scaler, pc->base + PERIOD(pwm->hwpwm));
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return 0;
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}
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static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
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u32 value;
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value = readl(pc->base + PWM_CONTROL);
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value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
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writel(value, pc->base + PWM_CONTROL);
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return 0;
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}
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static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
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u32 value;
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value = readl(pc->base + PWM_CONTROL);
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value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
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writel(value, pc->base + PWM_CONTROL);
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}
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static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
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enum pwm_polarity polarity)
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{
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struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
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u32 value;
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value = readl(pc->base + PWM_CONTROL);
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if (polarity == PWM_POLARITY_NORMAL)
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value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
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else
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value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
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writel(value, pc->base + PWM_CONTROL);
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return 0;
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}
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static const struct pwm_ops bcm2835_pwm_ops = {
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.request = bcm2835_pwm_request,
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.free = bcm2835_pwm_free,
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.config = bcm2835_pwm_config,
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.enable = bcm2835_pwm_enable,
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.disable = bcm2835_pwm_disable,
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.set_polarity = bcm2835_set_polarity,
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.owner = THIS_MODULE,
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};
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static int bcm2835_pwm_probe(struct platform_device *pdev)
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{
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struct bcm2835_pwm *pc;
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struct resource *res;
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int ret;
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pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
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if (!pc)
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return -ENOMEM;
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pc->dev = &pdev->dev;
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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pc->base = devm_ioremap_resource(&pdev->dev, res);
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if (IS_ERR(pc->base))
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return PTR_ERR(pc->base);
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pc->clk = devm_clk_get(&pdev->dev, NULL);
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if (IS_ERR(pc->clk)) {
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dev_err(&pdev->dev, "clock not found: %ld\n", PTR_ERR(pc->clk));
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return PTR_ERR(pc->clk);
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}
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ret = clk_prepare_enable(pc->clk);
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if (ret)
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return ret;
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pc->chip.dev = &pdev->dev;
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pc->chip.ops = &bcm2835_pwm_ops;
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pc->chip.npwm = 2;
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platform_set_drvdata(pdev, pc);
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ret = pwmchip_add(&pc->chip);
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if (ret < 0)
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goto add_fail;
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return 0;
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add_fail:
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clk_disable_unprepare(pc->clk);
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return ret;
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}
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static int bcm2835_pwm_remove(struct platform_device *pdev)
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{
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struct bcm2835_pwm *pc = platform_get_drvdata(pdev);
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clk_disable_unprepare(pc->clk);
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return pwmchip_remove(&pc->chip);
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}
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static const struct of_device_id bcm2835_pwm_of_match[] = {
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{ .compatible = "brcm,bcm2835-pwm", },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match);
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static struct platform_driver bcm2835_pwm_driver = {
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.driver = {
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.name = "bcm2835-pwm",
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.of_match_table = bcm2835_pwm_of_match,
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},
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.probe = bcm2835_pwm_probe,
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.remove = bcm2835_pwm_remove,
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};
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module_platform_driver(bcm2835_pwm_driver);
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MODULE_AUTHOR("Bart Tanghe <bart.tanghe@thomasmore.be>");
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MODULE_DESCRIPTION("Broadcom BCM2835 PWM driver");
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MODULE_LICENSE("GPL v2");
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