diff options
Diffstat (limited to 'drivers/pwm/pwm-lpc32xx.c')
| -rw-r--r-- | drivers/pwm/pwm-lpc32xx.c | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-lpc32xx.c b/drivers/pwm/pwm-lpc32xx.c new file mode 100644 index 000000000..806f0bb3a --- /dev/null +++ b/drivers/pwm/pwm-lpc32xx.c @@ -0,0 +1,175 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright 2012 Alexandre Pereira da Silva <aletes.xgr@gmail.com> + */ + +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/of_address.h> +#include <linux/platform_device.h> +#include <linux/pwm.h> +#include <linux/slab.h> + +struct lpc32xx_pwm_chip { + struct pwm_chip chip; + struct clk *clk; + void __iomem *base; +}; + +#define PWM_ENABLE BIT(31) +#define PWM_PIN_LEVEL BIT(30) + +#define to_lpc32xx_pwm_chip(_chip) \ + container_of(_chip, struct lpc32xx_pwm_chip, chip) + +static int lpc32xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, + int duty_ns, int period_ns) +{ + struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip); + unsigned long long c; + int period_cycles, duty_cycles; + u32 val; + c = clk_get_rate(lpc32xx->clk); + + /* The highest acceptable divisor is 256, which is represented by 0 */ + period_cycles = div64_u64(c * period_ns, + (unsigned long long)NSEC_PER_SEC * 256); + if (!period_cycles || period_cycles > 256) + return -ERANGE; + if (period_cycles == 256) + period_cycles = 0; + + /* Compute 256 x #duty/period value and care for corner cases */ + duty_cycles = div64_u64((unsigned long long)(period_ns - duty_ns) * 256, + period_ns); + if (!duty_cycles) + duty_cycles = 1; + if (duty_cycles > 255) + duty_cycles = 255; + + val = readl(lpc32xx->base); + val &= ~0xFFFF; + val |= (period_cycles << 8) | duty_cycles; + writel(val, lpc32xx->base); + + return 0; +} + +static int lpc32xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip); + u32 val; + int ret; + + ret = clk_prepare_enable(lpc32xx->clk); + if (ret) + return ret; + + val = readl(lpc32xx->base); + val |= PWM_ENABLE; + writel(val, lpc32xx->base); + + return 0; +} + +static void lpc32xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip); + u32 val; + + val = readl(lpc32xx->base); + val &= ~PWM_ENABLE; + writel(val, lpc32xx->base); + + clk_disable_unprepare(lpc32xx->clk); +} + +static int lpc32xx_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state) +{ + int err; + + if (state->polarity != PWM_POLARITY_NORMAL) + return -EINVAL; + + if (!state->enabled) { + if (pwm->state.enabled) + lpc32xx_pwm_disable(chip, pwm); + + return 0; + } + + err = lpc32xx_pwm_config(pwm->chip, pwm, state->duty_cycle, state->period); + if (err) + return err; + + if (!pwm->state.enabled) + err = lpc32xx_pwm_enable(chip, pwm); + + return err; +} + +static const struct pwm_ops lpc32xx_pwm_ops = { + .apply = lpc32xx_pwm_apply, + .owner = THIS_MODULE, +}; + +static int lpc32xx_pwm_probe(struct platform_device *pdev) +{ + struct lpc32xx_pwm_chip *lpc32xx; + int ret; + u32 val; + + lpc32xx = devm_kzalloc(&pdev->dev, sizeof(*lpc32xx), GFP_KERNEL); + if (!lpc32xx) + return -ENOMEM; + + lpc32xx->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(lpc32xx->base)) + return PTR_ERR(lpc32xx->base); + + lpc32xx->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(lpc32xx->clk)) + return PTR_ERR(lpc32xx->clk); + + lpc32xx->chip.dev = &pdev->dev; + lpc32xx->chip.ops = &lpc32xx_pwm_ops; + lpc32xx->chip.npwm = 1; + + /* If PWM is disabled, configure the output to the default value */ + val = readl(lpc32xx->base); + val &= ~PWM_PIN_LEVEL; + writel(val, lpc32xx->base); + + ret = devm_pwmchip_add(&pdev->dev, &lpc32xx->chip); + if (ret < 0) { + dev_err(&pdev->dev, "failed to add PWM chip, error %d\n", ret); + return ret; + } + + return 0; +} + +static const struct of_device_id lpc32xx_pwm_dt_ids[] = { + { .compatible = "nxp,lpc3220-pwm", }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, lpc32xx_pwm_dt_ids); + +static struct platform_driver lpc32xx_pwm_driver = { + .driver = { + .name = "lpc32xx-pwm", + .of_match_table = lpc32xx_pwm_dt_ids, + }, + .probe = lpc32xx_pwm_probe, +}; +module_platform_driver(lpc32xx_pwm_driver); + +MODULE_ALIAS("platform:lpc32xx-pwm"); +MODULE_AUTHOR("Alexandre Pereira da Silva <aletes.xgr@gmail.com>"); +MODULE_DESCRIPTION("LPC32XX PWM Driver"); +MODULE_LICENSE("GPL v2"); |