/* * Copyright 2014 Bart Tanghe <bart.tanghe@thomasmore.be> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; version 2. */ #include <linux/clk.h> #include <linux/err.h> #include <linux/io.h> #include <linux/module.h> #include <linux/of.h> #include <linux/platform_device.h> #include <linux/pwm.h> #define PWM_CONTROL 0x000 #define PWM_CONTROL_SHIFT(x) ((x) * 8) #define PWM_CONTROL_MASK 0xff #define PWM_MODE 0x80 /* set timer in PWM mode */ #define PWM_ENABLE (1 << 0) #define PWM_POLARITY (1 << 4) #define PERIOD(x) (((x) * 0x10) + 0x10) #define DUTY(x) (((x) * 0x10) + 0x14) #define MIN_PERIOD 108 /* 9.2 MHz max. PWM clock */ struct bcm2835_pwm { struct pwm_chip chip; struct device *dev; void __iomem *base; struct clk *clk; }; static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip) { return container_of(chip, struct bcm2835_pwm, chip); } static int bcm2835_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm) { struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); u32 value; value = readl(pc->base + PWM_CONTROL); value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm)); value |= (PWM_MODE << PWM_CONTROL_SHIFT(pwm->hwpwm)); writel(value, pc->base + PWM_CONTROL); return 0; } static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) { struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); u32 value; value = readl(pc->base + PWM_CONTROL); value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm)); writel(value, pc->base + PWM_CONTROL); } static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, int duty_ns, int period_ns) { struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); unsigned long rate = clk_get_rate(pc->clk); unsigned long scaler; if (!rate) { dev_err(pc->dev, "failed to get clock rate\n"); return -EINVAL; } scaler = NSEC_PER_SEC / rate; if (period_ns <= MIN_PERIOD) { dev_err(pc->dev, "period %d not supported, minimum %d\n", period_ns, MIN_PERIOD); return -EINVAL; } writel(duty_ns / scaler, pc->base + DUTY(pwm->hwpwm)); writel(period_ns / scaler, pc->base + PERIOD(pwm->hwpwm)); return 0; } static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) { struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); u32 value; value = readl(pc->base + PWM_CONTROL); value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm); writel(value, pc->base + PWM_CONTROL); return 0; } static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) { struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); u32 value; value = readl(pc->base + PWM_CONTROL); value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm)); writel(value, pc->base + PWM_CONTROL); } static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, enum pwm_polarity polarity) { struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); u32 value; value = readl(pc->base + PWM_CONTROL); if (polarity == PWM_POLARITY_NORMAL) value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm)); else value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm); writel(value, pc->base + PWM_CONTROL); return 0; } static const struct pwm_ops bcm2835_pwm_ops = { .request = bcm2835_pwm_request, .free = bcm2835_pwm_free, .config = bcm2835_pwm_config, .enable = bcm2835_pwm_enable, .disable = bcm2835_pwm_disable, .set_polarity = bcm2835_set_polarity, .owner = THIS_MODULE, }; static int bcm2835_pwm_probe(struct platform_device *pdev) { struct bcm2835_pwm *pc; struct resource *res; int ret; pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL); if (!pc) return -ENOMEM; pc->dev = &pdev->dev; res = platform_get_resource(pdev, IORESOURCE_MEM, 0); pc->base = devm_ioremap_resource(&pdev->dev, res); if (IS_ERR(pc->base)) return PTR_ERR(pc->base); pc->clk = devm_clk_get(&pdev->dev, NULL); if (IS_ERR(pc->clk)) { dev_err(&pdev->dev, "clock not found: %ld\n", PTR_ERR(pc->clk)); return PTR_ERR(pc->clk); } ret = clk_prepare_enable(pc->clk); if (ret) return ret; pc->chip.dev = &pdev->dev; pc->chip.ops = &bcm2835_pwm_ops; pc->chip.npwm = 2; pc->chip.of_xlate = of_pwm_xlate_with_flags; pc->chip.of_pwm_n_cells = 3; platform_set_drvdata(pdev, pc); ret = pwmchip_add(&pc->chip); if (ret < 0) goto add_fail; return 0; add_fail: clk_disable_unprepare(pc->clk); return ret; } static int bcm2835_pwm_remove(struct platform_device *pdev) { struct bcm2835_pwm *pc = platform_get_drvdata(pdev); clk_disable_unprepare(pc->clk); return pwmchip_remove(&pc->chip); } static const struct of_device_id bcm2835_pwm_of_match[] = { { .compatible = "brcm,bcm2835-pwm", }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match); static struct platform_driver bcm2835_pwm_driver = { .driver = { .name = "bcm2835-pwm", .of_match_table = bcm2835_pwm_of_match, }, .probe = bcm2835_pwm_probe, .remove = bcm2835_pwm_remove, }; module_platform_driver(bcm2835_pwm_driver); MODULE_AUTHOR("Bart Tanghe <bart.tanghe@thomasmore.be>"); MODULE_DESCRIPTION("Broadcom BCM2835 PWM driver"); MODULE_LICENSE("GPL v2");