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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>
329 lines
8 KiB
C
329 lines
8 KiB
C
/*
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* Marvell Berlin PWM driver
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*
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* Copyright (C) 2015 Marvell Technology Group Ltd.
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*
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* Author: Antoine Tenart <antoine.tenart@free-electrons.com>
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*
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* This file is licensed under the terms of the GNU General Public
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* License version 2. This program is licensed "as is" without any
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* warranty of any kind, whether express or implied.
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*/
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#include <linux/clk.h>
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#include <linux/io.h>
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#include <linux/kernel.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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#include <linux/slab.h>
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#define BERLIN_PWM_EN 0x0
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#define BERLIN_PWM_ENABLE BIT(0)
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#define BERLIN_PWM_CONTROL 0x4
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/*
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* The prescaler claims to support 8 different moduli, configured using the
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* low three bits of PWM_CONTROL. (Sequentially, they are 1, 4, 8, 16, 64,
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* 256, 1024, and 4096.) However, the moduli from 4 to 1024 appear to be
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* implemented by internally shifting TCNT left without adding additional
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* bits. So, the max TCNT that actually works for a modulus of 4 is 0x3fff;
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* for 8, 0x1fff; and so on. This means that those moduli are entirely
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* useless, as we could just do the shift ourselves. The 4096 modulus is
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* implemented with a real prescaler, so we do use that, but we treat it
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* as a flag instead of pretending the modulus is actually configurable.
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*/
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#define BERLIN_PWM_PRESCALE_4096 0x7
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#define BERLIN_PWM_INVERT_POLARITY BIT(3)
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#define BERLIN_PWM_DUTY 0x8
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#define BERLIN_PWM_TCNT 0xc
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#define BERLIN_PWM_MAX_TCNT 65535
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struct berlin_pwm_channel {
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u32 enable;
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u32 ctrl;
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u32 duty;
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u32 tcnt;
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};
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struct berlin_pwm_chip {
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struct pwm_chip chip;
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struct clk *clk;
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void __iomem *base;
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};
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static inline struct berlin_pwm_chip *to_berlin_pwm_chip(struct pwm_chip *chip)
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{
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return container_of(chip, struct berlin_pwm_chip, chip);
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}
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static inline u32 berlin_pwm_readl(struct berlin_pwm_chip *bpc,
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unsigned int channel, unsigned long offset)
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{
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return readl_relaxed(bpc->base + channel * 0x10 + offset);
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}
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static inline void berlin_pwm_writel(struct berlin_pwm_chip *bpc,
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unsigned int channel, u32 value,
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unsigned long offset)
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{
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writel_relaxed(value, bpc->base + channel * 0x10 + offset);
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}
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static int berlin_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct berlin_pwm_channel *channel;
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channel = kzalloc(sizeof(*channel), GFP_KERNEL);
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if (!channel)
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return -ENOMEM;
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return pwm_set_chip_data(pwm, channel);
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}
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static void berlin_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct berlin_pwm_channel *channel = pwm_get_chip_data(pwm);
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kfree(channel);
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}
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static int berlin_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
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u64 duty_ns, u64 period_ns)
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{
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struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
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bool prescale_4096 = false;
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u32 value, duty, period;
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u64 cycles;
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cycles = clk_get_rate(bpc->clk);
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cycles *= period_ns;
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do_div(cycles, NSEC_PER_SEC);
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if (cycles > BERLIN_PWM_MAX_TCNT) {
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prescale_4096 = true;
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cycles >>= 12; // Prescaled by 4096
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if (cycles > BERLIN_PWM_MAX_TCNT)
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return -ERANGE;
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}
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period = cycles;
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cycles *= duty_ns;
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do_div(cycles, period_ns);
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duty = cycles;
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value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_CONTROL);
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if (prescale_4096)
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value |= BERLIN_PWM_PRESCALE_4096;
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else
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value &= ~BERLIN_PWM_PRESCALE_4096;
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berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_CONTROL);
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berlin_pwm_writel(bpc, pwm->hwpwm, duty, BERLIN_PWM_DUTY);
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berlin_pwm_writel(bpc, pwm->hwpwm, period, BERLIN_PWM_TCNT);
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return 0;
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}
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static int berlin_pwm_set_polarity(struct pwm_chip *chip,
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struct pwm_device *pwm,
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enum pwm_polarity polarity)
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{
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struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
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u32 value;
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value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_CONTROL);
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if (polarity == PWM_POLARITY_NORMAL)
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value &= ~BERLIN_PWM_INVERT_POLARITY;
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else
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value |= BERLIN_PWM_INVERT_POLARITY;
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berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_CONTROL);
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return 0;
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}
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static int berlin_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
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u32 value;
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value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_EN);
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value |= BERLIN_PWM_ENABLE;
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berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_EN);
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return 0;
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}
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static void berlin_pwm_disable(struct pwm_chip *chip,
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struct pwm_device *pwm)
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{
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struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
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u32 value;
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value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_EN);
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value &= ~BERLIN_PWM_ENABLE;
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berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_EN);
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}
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static int berlin_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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int err;
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bool enabled = pwm->state.enabled;
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if (state->polarity != pwm->state.polarity) {
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if (enabled) {
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berlin_pwm_disable(chip, pwm);
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enabled = false;
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}
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err = berlin_pwm_set_polarity(chip, pwm, state->polarity);
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if (err)
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return err;
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}
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if (!state->enabled) {
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if (enabled)
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berlin_pwm_disable(chip, pwm);
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return 0;
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}
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err = berlin_pwm_config(chip, pwm, state->duty_cycle, state->period);
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if (err)
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return err;
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if (!enabled)
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return berlin_pwm_enable(chip, pwm);
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return 0;
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}
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static const struct pwm_ops berlin_pwm_ops = {
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.request = berlin_pwm_request,
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.free = berlin_pwm_free,
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.apply = berlin_pwm_apply,
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.owner = THIS_MODULE,
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};
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static const struct of_device_id berlin_pwm_match[] = {
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{ .compatible = "marvell,berlin-pwm" },
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{ },
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};
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MODULE_DEVICE_TABLE(of, berlin_pwm_match);
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static int berlin_pwm_probe(struct platform_device *pdev)
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{
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struct berlin_pwm_chip *bpc;
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int ret;
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bpc = devm_kzalloc(&pdev->dev, sizeof(*bpc), GFP_KERNEL);
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if (!bpc)
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return -ENOMEM;
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bpc->base = devm_platform_ioremap_resource(pdev, 0);
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if (IS_ERR(bpc->base))
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return PTR_ERR(bpc->base);
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bpc->clk = devm_clk_get(&pdev->dev, NULL);
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if (IS_ERR(bpc->clk))
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return PTR_ERR(bpc->clk);
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ret = clk_prepare_enable(bpc->clk);
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if (ret)
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return ret;
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bpc->chip.dev = &pdev->dev;
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bpc->chip.ops = &berlin_pwm_ops;
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bpc->chip.npwm = 4;
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ret = pwmchip_add(&bpc->chip);
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if (ret < 0) {
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dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
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clk_disable_unprepare(bpc->clk);
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return ret;
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}
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platform_set_drvdata(pdev, bpc);
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return 0;
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}
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static void berlin_pwm_remove(struct platform_device *pdev)
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{
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struct berlin_pwm_chip *bpc = platform_get_drvdata(pdev);
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pwmchip_remove(&bpc->chip);
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clk_disable_unprepare(bpc->clk);
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}
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#ifdef CONFIG_PM_SLEEP
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static int berlin_pwm_suspend(struct device *dev)
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{
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struct berlin_pwm_chip *bpc = dev_get_drvdata(dev);
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unsigned int i;
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for (i = 0; i < bpc->chip.npwm; i++) {
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struct berlin_pwm_channel *channel;
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channel = pwm_get_chip_data(&bpc->chip.pwms[i]);
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if (!channel)
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continue;
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channel->enable = berlin_pwm_readl(bpc, i, BERLIN_PWM_ENABLE);
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channel->ctrl = berlin_pwm_readl(bpc, i, BERLIN_PWM_CONTROL);
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channel->duty = berlin_pwm_readl(bpc, i, BERLIN_PWM_DUTY);
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channel->tcnt = berlin_pwm_readl(bpc, i, BERLIN_PWM_TCNT);
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}
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clk_disable_unprepare(bpc->clk);
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return 0;
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}
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static int berlin_pwm_resume(struct device *dev)
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{
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struct berlin_pwm_chip *bpc = dev_get_drvdata(dev);
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unsigned int i;
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int ret;
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ret = clk_prepare_enable(bpc->clk);
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if (ret)
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return ret;
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for (i = 0; i < bpc->chip.npwm; i++) {
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struct berlin_pwm_channel *channel;
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channel = pwm_get_chip_data(&bpc->chip.pwms[i]);
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if (!channel)
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continue;
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berlin_pwm_writel(bpc, i, channel->ctrl, BERLIN_PWM_CONTROL);
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berlin_pwm_writel(bpc, i, channel->duty, BERLIN_PWM_DUTY);
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berlin_pwm_writel(bpc, i, channel->tcnt, BERLIN_PWM_TCNT);
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berlin_pwm_writel(bpc, i, channel->enable, BERLIN_PWM_ENABLE);
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}
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return 0;
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}
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#endif
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static SIMPLE_DEV_PM_OPS(berlin_pwm_pm_ops, berlin_pwm_suspend,
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berlin_pwm_resume);
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static struct platform_driver berlin_pwm_driver = {
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.probe = berlin_pwm_probe,
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.remove_new = berlin_pwm_remove,
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.driver = {
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.name = "berlin-pwm",
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.of_match_table = berlin_pwm_match,
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.pm = &berlin_pwm_pm_ops,
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},
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};
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module_platform_driver(berlin_pwm_driver);
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MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>");
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MODULE_DESCRIPTION("Marvell Berlin PWM driver");
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MODULE_LICENSE("GPL v2");
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