diff options
Diffstat (limited to 'drivers/pwm/pwm-bcm2835.c')
| -rw-r--r-- | drivers/pwm/pwm-bcm2835.c | 214 |
1 files changed, 214 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c new file mode 100644 index 000000000..e340ad79a --- /dev/null +++ b/drivers/pwm/pwm-bcm2835.c @@ -0,0 +1,214 @@ +/* + * 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.base = -1; + 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"); |