diff options
Diffstat (limited to 'drivers/pwm/pwm-ep93xx.c')
| -rw-r--r-- | drivers/pwm/pwm-ep93xx.c | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-ep93xx.c b/drivers/pwm/pwm-ep93xx.c new file mode 100644 index 000000000..c45a75e65 --- /dev/null +++ b/drivers/pwm/pwm-ep93xx.c @@ -0,0 +1,205 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * PWM framework driver for Cirrus Logic EP93xx + * + * Copyright (c) 2009 Matthieu Crapet <mcrapet@gmail.com> + * Copyright (c) 2009, 2013 H Hartley Sweeten <hsweeten@visionengravers.com> + * + * EP9301/02 have only one channel: + * platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14) + * + * EP9307 has only one channel: + * platform device ep93xx-pwm.0 - PWMOUT + * + * EP9312/15 have two channels: + * platform device ep93xx-pwm.0 - PWMOUT + * platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14) + */ + +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/slab.h> +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/pwm.h> + +#include <asm/div64.h> + +#include <linux/soc/cirrus/ep93xx.h> /* for ep93xx_pwm_{acquire,release}_gpio() */ + +#define EP93XX_PWMx_TERM_COUNT 0x00 +#define EP93XX_PWMx_DUTY_CYCLE 0x04 +#define EP93XX_PWMx_ENABLE 0x08 +#define EP93XX_PWMx_INVERT 0x0c + +struct ep93xx_pwm { + void __iomem *base; + struct clk *clk; + struct pwm_chip chip; +}; + +static inline struct ep93xx_pwm *to_ep93xx_pwm(struct pwm_chip *chip) +{ + return container_of(chip, struct ep93xx_pwm, chip); +} + +static int ep93xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct platform_device *pdev = to_platform_device(chip->dev); + + return ep93xx_pwm_acquire_gpio(pdev); +} + +static void ep93xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct platform_device *pdev = to_platform_device(chip->dev); + + ep93xx_pwm_release_gpio(pdev); +} + +static int ep93xx_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state) +{ + int ret; + struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip); + bool enabled = state->enabled; + void __iomem *base = ep93xx_pwm->base; + unsigned long long c; + unsigned long period_cycles; + unsigned long duty_cycles; + unsigned long term; + + if (state->polarity != pwm->state.polarity) { + if (enabled) { + writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_ENABLE); + clk_disable_unprepare(ep93xx_pwm->clk); + enabled = false; + } + + /* + * The clock needs to be enabled to access the PWM registers. + * Polarity can only be changed when the PWM is disabled. + */ + ret = clk_prepare_enable(ep93xx_pwm->clk); + if (ret) + return ret; + + if (state->polarity == PWM_POLARITY_INVERSED) + writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_INVERT); + else + writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_INVERT); + + clk_disable_unprepare(ep93xx_pwm->clk); + } + + if (!state->enabled) { + if (enabled) { + writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_ENABLE); + clk_disable_unprepare(ep93xx_pwm->clk); + } + + return 0; + } + + /* + * The clock needs to be enabled to access the PWM registers. + * Configuration can be changed at any time. + */ + if (!pwm_is_enabled(pwm)) { + ret = clk_prepare_enable(ep93xx_pwm->clk); + if (ret) + return ret; + } + + c = clk_get_rate(ep93xx_pwm->clk); + c *= state->period; + do_div(c, 1000000000); + period_cycles = c; + + c = period_cycles; + c *= state->duty_cycle; + do_div(c, state->period); + duty_cycles = c; + + if (period_cycles < 0x10000 && duty_cycles < 0x10000) { + term = readw(base + EP93XX_PWMx_TERM_COUNT); + + /* Order is important if PWM is running */ + if (period_cycles > term) { + writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT); + writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE); + } else { + writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE); + writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT); + } + ret = 0; + } else { + ret = -EINVAL; + } + + if (!pwm_is_enabled(pwm)) + clk_disable_unprepare(ep93xx_pwm->clk); + + if (ret) + return ret; + + if (!enabled) { + ret = clk_prepare_enable(ep93xx_pwm->clk); + if (ret) + return ret; + + writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_ENABLE); + } + + return 0; +} + +static const struct pwm_ops ep93xx_pwm_ops = { + .request = ep93xx_pwm_request, + .free = ep93xx_pwm_free, + .apply = ep93xx_pwm_apply, + .owner = THIS_MODULE, +}; + +static int ep93xx_pwm_probe(struct platform_device *pdev) +{ + struct ep93xx_pwm *ep93xx_pwm; + int ret; + + ep93xx_pwm = devm_kzalloc(&pdev->dev, sizeof(*ep93xx_pwm), GFP_KERNEL); + if (!ep93xx_pwm) + return -ENOMEM; + + ep93xx_pwm->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(ep93xx_pwm->base)) + return PTR_ERR(ep93xx_pwm->base); + + ep93xx_pwm->clk = devm_clk_get(&pdev->dev, "pwm_clk"); + if (IS_ERR(ep93xx_pwm->clk)) + return PTR_ERR(ep93xx_pwm->clk); + + ep93xx_pwm->chip.dev = &pdev->dev; + ep93xx_pwm->chip.ops = &ep93xx_pwm_ops; + ep93xx_pwm->chip.npwm = 1; + + ret = devm_pwmchip_add(&pdev->dev, &ep93xx_pwm->chip); + if (ret < 0) + return ret; + + return 0; +} + +static struct platform_driver ep93xx_pwm_driver = { + .driver = { + .name = "ep93xx-pwm", + }, + .probe = ep93xx_pwm_probe, +}; +module_platform_driver(ep93xx_pwm_driver); + +MODULE_DESCRIPTION("Cirrus Logic EP93xx PWM driver"); +MODULE_AUTHOR("Matthieu Crapet <mcrapet@gmail.com>"); +MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>"); +MODULE_ALIAS("platform:ep93xx-pwm"); +MODULE_LICENSE("GPL"); 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