drivers/pwm/pwm-ep93xx.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * PWM framework driver for Cirrus Logic EP93xx
0004  *
0005  * Copyright (c) 2009        Matthieu Crapet <mcrapet@gmail.com>
0006  * Copyright (c) 2009, 2013  H Hartley Sweeten <hsweeten@visionengravers.com>
0007  *
0008  * EP9301/02 have only one channel:
0009  *   platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14)
0010  *
0011  * EP9307 has only one channel:
0012  *   platform device ep93xx-pwm.0 - PWMOUT
0013  *
0014  * EP9312/15 have two channels:
0015  *   platform device ep93xx-pwm.0 - PWMOUT
0016  *   platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14)
0017  */
0018
0019 #include <linux/module.h>
0020 #include <linux/platform_device.h>
0021 #include <linux/slab.h>
0022 #include <linux/clk.h>
0023 #include <linux/err.h>
0024 #include <linux/io.h>
0025 #include <linux/pwm.h>
0026
0027 #include <asm/div64.h>
0028
0029 #include <linux/soc/cirrus/ep93xx.h>    /* for ep93xx_pwm_{acquire,release}_gpio() */
0030
0031 #define EP93XX_PWMx_TERM_COUNT  0x00
0032 #define EP93XX_PWMx_DUTY_CYCLE  0x04
0033 #define EP93XX_PWMx_ENABLE  0x08
0034 #define EP93XX_PWMx_INVERT  0x0c
0035
0036 struct ep93xx_pwm {
0037     void __iomem *base;
0038     struct clk *clk;
0039     struct pwm_chip chip;
0040 };
0041
0042 static inline struct ep93xx_pwm *to_ep93xx_pwm(struct pwm_chip *chip)
0043 {
0044     return container_of(chip, struct ep93xx_pwm, chip);
0045 }
0046
0047 static int ep93xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
0048 {
0049     struct platform_device *pdev = to_platform_device(chip->dev);
0050
0051     return ep93xx_pwm_acquire_gpio(pdev);
0052 }
0053
0054 static void ep93xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
0055 {
0056     struct platform_device *pdev = to_platform_device(chip->dev);
0057
0058     ep93xx_pwm_release_gpio(pdev);
0059 }
0060
0061 static int ep93xx_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
0062                 const struct pwm_state *state)
0063 {
0064     int ret;
0065     struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
0066     bool enabled = state->enabled;
0067     void __iomem *base = ep93xx_pwm->base;
0068     unsigned long long c;
0069     unsigned long period_cycles;
0070     unsigned long duty_cycles;
0071     unsigned long term;
0072
0073     if (state->polarity != pwm->state.polarity) {
0074         if (enabled) {
0075             writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
0076             clk_disable_unprepare(ep93xx_pwm->clk);
0077             enabled = false;
0078         }
0079
0080         /*
0081          * The clock needs to be enabled to access the PWM registers.
0082          * Polarity can only be changed when the PWM is disabled.
0083          */
0084         ret = clk_prepare_enable(ep93xx_pwm->clk);
0085         if (ret)
0086             return ret;
0087
0088         if (state->polarity == PWM_POLARITY_INVERSED)
0089             writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
0090         else
0091             writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
0092
0093         clk_disable_unprepare(ep93xx_pwm->clk);
0094     }
0095
0096     if (!state->enabled) {
0097         if (enabled) {
0098             writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
0099             clk_disable_unprepare(ep93xx_pwm->clk);
0100         }
0101
0102         return 0;
0103     }
0104
0105     /*
0106      * The clock needs to be enabled to access the PWM registers.
0107      * Configuration can be changed at any time.
0108      */
0109     if (!pwm_is_enabled(pwm)) {
0110         ret = clk_prepare_enable(ep93xx_pwm->clk);
0111         if (ret)
0112             return ret;
0113     }
0114
0115     c = clk_get_rate(ep93xx_pwm->clk);
0116     c *= state->period;
0117     do_div(c, 1000000000);
0118     period_cycles = c;
0119
0120     c = period_cycles;
0121     c *= state->duty_cycle;
0122     do_div(c, state->period);
0123     duty_cycles = c;
0124
0125     if (period_cycles < 0x10000 && duty_cycles < 0x10000) {
0126         term = readw(base + EP93XX_PWMx_TERM_COUNT);
0127
0128         /* Order is important if PWM is running */
0129         if (period_cycles > term) {
0130             writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
0131             writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
0132         } else {
0133             writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
0134             writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
0135         }
0136         ret = 0;
0137     } else {
0138         ret = -EINVAL;
0139     }
0140
0141     if (!pwm_is_enabled(pwm))
0142         clk_disable_unprepare(ep93xx_pwm->clk);
0143
0144     if (ret)
0145         return ret;
0146
0147     if (!enabled) {
0148         ret = clk_prepare_enable(ep93xx_pwm->clk);
0149         if (ret)
0150             return ret;
0151
0152         writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
0153     }
0154
0155     return 0;
0156 }
0157
0158 static const struct pwm_ops ep93xx_pwm_ops = {
0159     .request = ep93xx_pwm_request,
0160     .free = ep93xx_pwm_free,
0161     .apply = ep93xx_pwm_apply,
0162     .owner = THIS_MODULE,
0163 };
0164
0165 static int ep93xx_pwm_probe(struct platform_device *pdev)
0166 {
0167     struct ep93xx_pwm *ep93xx_pwm;
0168     int ret;
0169
0170     ep93xx_pwm = devm_kzalloc(&pdev->dev, sizeof(*ep93xx_pwm), GFP_KERNEL);
0171     if (!ep93xx_pwm)
0172         return -ENOMEM;
0173
0174     ep93xx_pwm->base = devm_platform_ioremap_resource(pdev, 0);
0175     if (IS_ERR(ep93xx_pwm->base))
0176         return PTR_ERR(ep93xx_pwm->base);
0177
0178     ep93xx_pwm->clk = devm_clk_get(&pdev->dev, "pwm_clk");
0179     if (IS_ERR(ep93xx_pwm->clk))
0180         return PTR_ERR(ep93xx_pwm->clk);
0181
0182     ep93xx_pwm->chip.dev = &pdev->dev;
0183     ep93xx_pwm->chip.ops = &ep93xx_pwm_ops;
0184     ep93xx_pwm->chip.npwm = 1;
0185
0186     ret = devm_pwmchip_add(&pdev->dev, &ep93xx_pwm->chip);
0187     if (ret < 0)
0188         return ret;
0189
0190     return 0;
0191 }
0192
0193 static struct platform_driver ep93xx_pwm_driver = {
0194     .driver = {
0195         .name = "ep93xx-pwm",
0196     },
0197     .probe = ep93xx_pwm_probe,
0198 };
0199 module_platform_driver(ep93xx_pwm_driver);
0200
0201 MODULE_DESCRIPTION("Cirrus Logic EP93xx PWM driver");
0202 MODULE_AUTHOR("Matthieu Crapet <mcrapet@gmail.com>");
0203 MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
0204 MODULE_ALIAS("platform:ep93xx-pwm");
0205 MODULE_LICENSE("GPL");