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![Uwe Kleine-König](/assets/img/avatar_default.png)
The .remove() callback for a platform driver returns an int which makes many driver authors wrongly assume it's possible to do error handling by returning an error code. However the value returned is (mostly) ignored and this typically results in resource leaks. To improve here there is a quest to make the remove callback return void. In the first step of this quest all drivers are converted to .remove_new() which already returns void. Trivially convert this driver from always returning zero in the remove callback to the void returning variant. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
203 lines
5 KiB
C
203 lines
5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright 2014 Bart Tanghe <bart.tanghe@thomasmore.be>
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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 PERIOD_MIN 0x2
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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_apply(struct pwm_chip *chip, struct pwm_device *pwm,
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const struct pwm_state *state)
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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 long period_cycles;
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u64 max_period;
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u32 val;
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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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/*
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* period_cycles must be a 32 bit value, so period * rate / NSEC_PER_SEC
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* must be <= U32_MAX. As U32_MAX * NSEC_PER_SEC < U64_MAX the
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* multiplication period * rate doesn't overflow.
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* To calculate the maximal possible period that guarantees the
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* above inequality:
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*
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* round(period * rate / NSEC_PER_SEC) <= U32_MAX
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* <=> period * rate / NSEC_PER_SEC < U32_MAX + 0.5
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* <=> period * rate < (U32_MAX + 0.5) * NSEC_PER_SEC
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* <=> period < ((U32_MAX + 0.5) * NSEC_PER_SEC) / rate
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* <=> period < ((U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC/2) / rate
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* <=> period <= ceil((U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC/2) / rate) - 1
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*/
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max_period = DIV_ROUND_UP_ULL((u64)U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC / 2, rate) - 1;
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if (state->period > max_period)
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return -EINVAL;
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/* set period */
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period_cycles = DIV_ROUND_CLOSEST_ULL(state->period * rate, NSEC_PER_SEC);
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/* don't accept a period that is too small */
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if (period_cycles < PERIOD_MIN)
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return -EINVAL;
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writel(period_cycles, pc->base + PERIOD(pwm->hwpwm));
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/* set duty cycle */
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val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle * rate, NSEC_PER_SEC);
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writel(val, pc->base + DUTY(pwm->hwpwm));
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/* set polarity */
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val = readl(pc->base + PWM_CONTROL);
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if (state->polarity == PWM_POLARITY_NORMAL)
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val &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
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else
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val |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
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/* enable/disable */
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if (state->enabled)
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val |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
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else
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val &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
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writel(val, 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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.apply = bcm2835_pwm_apply,
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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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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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pc->base = devm_platform_ioremap_resource(pdev, 0);
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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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return dev_err_probe(&pdev->dev, PTR_ERR(pc->clk),
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"clock not found\n");
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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 void 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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pwmchip_remove(&pc->chip);
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clk_disable_unprepare(pc->clk);
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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_new = 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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