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