230 lines
5.9 KiB
C
230 lines
5.9 KiB
C
/*
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* PWM framework driver for Cirrus Logic EP93xx
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*
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* Copyright (c) 2009 Matthieu Crapet <mcrapet@gmail.com>
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* Copyright (c) 2009, 2013 H Hartley Sweeten <hsweeten@visionengravers.com>
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*
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* EP9301/02 have only one channel:
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* platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14)
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*
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* EP9307 has only one channel:
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* platform device ep93xx-pwm.0 - PWMOUT
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*
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* EP9312/15 have two channels:
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* platform device ep93xx-pwm.0 - PWMOUT
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* platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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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/pwm.h>
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#include <asm/div64.h>
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#include <mach/platform.h> /* for ep93xx_pwm_{acquire,release}_gpio() */
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#define EP93XX_PWMx_TERM_COUNT 0x00
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#define EP93XX_PWMx_DUTY_CYCLE 0x04
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#define EP93XX_PWMx_ENABLE 0x08
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#define EP93XX_PWMx_INVERT 0x0c
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struct ep93xx_pwm {
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void __iomem *base;
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struct clk *clk;
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struct pwm_chip chip;
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};
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static inline struct ep93xx_pwm *to_ep93xx_pwm(struct pwm_chip *chip)
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{
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return container_of(chip, struct ep93xx_pwm, chip);
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}
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static int ep93xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct platform_device *pdev = to_platform_device(chip->dev);
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return ep93xx_pwm_acquire_gpio(pdev);
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}
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static void ep93xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct platform_device *pdev = to_platform_device(chip->dev);
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ep93xx_pwm_release_gpio(pdev);
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}
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static int ep93xx_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 ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
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void __iomem *base = ep93xx_pwm->base;
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unsigned long long c;
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unsigned long period_cycles;
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unsigned long duty_cycles;
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unsigned long term;
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int ret = 0;
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/*
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* The clock needs to be enabled to access the PWM registers.
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* Configuration can be changed at any time.
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*/
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if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
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ret = clk_enable(ep93xx_pwm->clk);
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if (ret)
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return ret;
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}
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c = clk_get_rate(ep93xx_pwm->clk);
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c *= period_ns;
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do_div(c, 1000000000);
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period_cycles = c;
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c = period_cycles;
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c *= duty_ns;
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do_div(c, period_ns);
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duty_cycles = c;
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if (period_cycles < 0x10000 && duty_cycles < 0x10000) {
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term = readw(base + EP93XX_PWMx_TERM_COUNT);
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/* Order is important if PWM is running */
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if (period_cycles > term) {
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writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
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writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
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} else {
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writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
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writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
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}
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} else {
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ret = -EINVAL;
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}
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if (!test_bit(PWMF_ENABLED, &pwm->flags))
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clk_disable(ep93xx_pwm->clk);
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return ret;
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}
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static int ep93xx_pwm_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 ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
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int ret;
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/*
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* The clock needs to be enabled to access the PWM registers.
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* Polarity can only be changed when the PWM is disabled.
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*/
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ret = clk_enable(ep93xx_pwm->clk);
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if (ret)
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return ret;
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if (polarity == PWM_POLARITY_INVERSED)
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writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
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else
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writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
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clk_disable(ep93xx_pwm->clk);
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return 0;
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}
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static int ep93xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
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int ret;
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ret = clk_enable(ep93xx_pwm->clk);
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if (ret)
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return ret;
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writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
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return 0;
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}
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static void ep93xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
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writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
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clk_disable(ep93xx_pwm->clk);
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}
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static const struct pwm_ops ep93xx_pwm_ops = {
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.request = ep93xx_pwm_request,
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.free = ep93xx_pwm_free,
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.config = ep93xx_pwm_config,
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.set_polarity = ep93xx_pwm_polarity,
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.enable = ep93xx_pwm_enable,
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.disable = ep93xx_pwm_disable,
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.owner = THIS_MODULE,
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};
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static int ep93xx_pwm_probe(struct platform_device *pdev)
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{
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struct ep93xx_pwm *ep93xx_pwm;
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struct resource *res;
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int ret;
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ep93xx_pwm = devm_kzalloc(&pdev->dev, sizeof(*ep93xx_pwm), GFP_KERNEL);
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if (!ep93xx_pwm)
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return -ENOMEM;
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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ep93xx_pwm->base = devm_ioremap_resource(&pdev->dev, res);
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if (IS_ERR(ep93xx_pwm->base))
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return PTR_ERR(ep93xx_pwm->base);
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ep93xx_pwm->clk = devm_clk_get(&pdev->dev, "pwm_clk");
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if (IS_ERR(ep93xx_pwm->clk))
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return PTR_ERR(ep93xx_pwm->clk);
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ep93xx_pwm->chip.dev = &pdev->dev;
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ep93xx_pwm->chip.ops = &ep93xx_pwm_ops;
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ep93xx_pwm->chip.base = -1;
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ep93xx_pwm->chip.npwm = 1;
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ret = pwmchip_add(&ep93xx_pwm->chip);
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if (ret < 0)
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return ret;
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platform_set_drvdata(pdev, ep93xx_pwm);
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return 0;
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}
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static int ep93xx_pwm_remove(struct platform_device *pdev)
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{
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struct ep93xx_pwm *ep93xx_pwm = platform_get_drvdata(pdev);
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return pwmchip_remove(&ep93xx_pwm->chip);
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}
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static struct platform_driver ep93xx_pwm_driver = {
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.driver = {
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.name = "ep93xx-pwm",
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},
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.probe = ep93xx_pwm_probe,
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.remove = ep93xx_pwm_remove,
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};
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module_platform_driver(ep93xx_pwm_driver);
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MODULE_DESCRIPTION("Cirrus Logic EP93xx PWM driver");
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MODULE_AUTHOR("Matthieu Crapet <mcrapet@gmail.com>");
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MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
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MODULE_ALIAS("platform:ep93xx-pwm");
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MODULE_LICENSE("GPL");
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