332 lines
8.0 KiB
C
332 lines
8.0 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 int 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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return 0;
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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 = 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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