diff options
Diffstat (limited to 'drivers/pwm/pwm-rockchip.c')
| -rw-r--r-- | drivers/pwm/pwm-rockchip.c | 177 |
1 files changed, 177 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-rockchip.c b/drivers/pwm/pwm-rockchip.c new file mode 100644 index 000000000000..eec214568193 --- /dev/null +++ b/drivers/pwm/pwm-rockchip.c @@ -0,0 +1,177 @@ +/* + * PWM driver for Rockchip SoCs + * + * Copyright (C) 2014 Beniamino Galvani <b.galvani@gmail.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * version 2 as published by the Free Software Foundation. + */ + +#include <linux/clk.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/pwm.h> +#include <linux/time.h> + +#define PWM_CNTR 0x00 /* Counter register */ +#define PWM_HRC 0x04 /* High reference register */ +#define PWM_LRC 0x08 /* Low reference register */ +#define PWM_CTRL 0x0c /* Control register */ +#define PWM_CTRL_TIMER_EN (1 << 0) +#define PWM_CTRL_OUTPUT_EN (1 << 3) + +#define PRESCALER 2 + +struct rockchip_pwm_chip { + struct pwm_chip chip; + struct clk *clk; + void __iomem *base; +}; + +static inline struct rockchip_pwm_chip *to_rockchip_pwm_chip(struct pwm_chip *c) +{ + return container_of(c, struct rockchip_pwm_chip, chip); +} + +static int rockchip_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, + int duty_ns, int period_ns) +{ + struct rockchip_pwm_chip *pc = to_rockchip_pwm_chip(chip); + unsigned long period, duty; + u64 clk_rate, div; + int ret; + + clk_rate = clk_get_rate(pc->clk); + + /* + * Since period and duty cycle registers have a width of 32 + * bits, every possible input period can be obtained using the + * default prescaler value for all practical clock rate values. + */ + div = clk_rate * period_ns; + do_div(div, PRESCALER * NSEC_PER_SEC); + period = div; + + div = clk_rate * duty_ns; + do_div(div, PRESCALER * NSEC_PER_SEC); + duty = div; + + ret = clk_enable(pc->clk); + if (ret) + return ret; + + writel(period, pc->base + PWM_LRC); + writel(duty, pc->base + PWM_HRC); + writel(0, pc->base + PWM_CNTR); + + clk_disable(pc->clk); + + return 0; +} + +static int rockchip_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct rockchip_pwm_chip *pc = to_rockchip_pwm_chip(chip); + int ret; + u32 val; + + ret = clk_enable(pc->clk); + if (ret) + return ret; + + val = readl_relaxed(pc->base + PWM_CTRL); + val |= PWM_CTRL_OUTPUT_EN | PWM_CTRL_TIMER_EN; + writel_relaxed(val, pc->base + PWM_CTRL); + + return 0; +} + +static void rockchip_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct rockchip_pwm_chip *pc = to_rockchip_pwm_chip(chip); + u32 val; + + val = readl_relaxed(pc->base + PWM_CTRL); + val &= ~(PWM_CTRL_OUTPUT_EN | PWM_CTRL_TIMER_EN); + writel_relaxed(val, pc->base + PWM_CTRL); + + clk_disable(pc->clk); +} + +static const struct pwm_ops rockchip_pwm_ops = { + .config = rockchip_pwm_config, + .enable = rockchip_pwm_enable, + .disable = rockchip_pwm_disable, + .owner = THIS_MODULE, +}; + +static int rockchip_pwm_probe(struct platform_device *pdev) +{ + struct rockchip_pwm_chip *pc; + struct resource *r; + int ret; + + pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL); + if (!pc) + return -ENOMEM; + + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + pc->base = devm_ioremap_resource(&pdev->dev, r); + if (IS_ERR(pc->base)) + return PTR_ERR(pc->base); + + pc->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(pc->clk)) + return PTR_ERR(pc->clk); + + ret = clk_prepare(pc->clk); + if (ret) + return ret; + + platform_set_drvdata(pdev, pc); + + pc->chip.dev = &pdev->dev; + pc->chip.ops = &rockchip_pwm_ops; + pc->chip.base = -1; + pc->chip.npwm = 1; + + ret = pwmchip_add(&pc->chip); + if (ret < 0) { + clk_unprepare(pc->clk); + dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret); + } + + return ret; +} + +static int rockchip_pwm_remove(struct platform_device *pdev) +{ + struct rockchip_pwm_chip *pc = platform_get_drvdata(pdev); + + clk_unprepare(pc->clk); + + return pwmchip_remove(&pc->chip); +} + +static const struct of_device_id rockchip_pwm_dt_ids[] = { + { .compatible = "rockchip,rk2928-pwm" }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, rockchip_pwm_dt_ids); + +static struct platform_driver rockchip_pwm_driver = { + .driver = { + .name = "rockchip-pwm", + .of_match_table = rockchip_pwm_dt_ids, + }, + .probe = rockchip_pwm_probe, + .remove = rockchip_pwm_remove, +}; +module_platform_driver(rockchip_pwm_driver); + +MODULE_AUTHOR("Beniamino Galvani <b.galvani@gmail.com>"); +MODULE_DESCRIPTION("Rockchip SoC PWM driver"); +MODULE_LICENSE("GPL v2"); |