diff options
Diffstat (limited to 'drivers/pwm/pwm-imx1.c')
| -rw-r--r-- | drivers/pwm/pwm-imx1.c | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-imx1.c b/drivers/pwm/pwm-imx1.c new file mode 100644 index 000000000..1f2eb1c8f --- /dev/null +++ b/drivers/pwm/pwm-imx1.c @@ -0,0 +1,198 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * simple driver for PWM (Pulse Width Modulator) controller + * + * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com> + */ + +#include <linux/bitfield.h> +#include <linux/bitops.h> +#include <linux/clk.h> +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/of_device.h> +#include <linux/platform_device.h> +#include <linux/pwm.h> +#include <linux/slab.h> + +#define MX1_PWMC 0x00 /* PWM Control Register */ +#define MX1_PWMS 0x04 /* PWM Sample Register */ +#define MX1_PWMP 0x08 /* PWM Period Register */ + +#define MX1_PWMC_EN BIT(4) + +struct pwm_imx1_chip { + struct clk *clk_ipg; + struct clk *clk_per; + void __iomem *mmio_base; + struct pwm_chip chip; +}; + +#define to_pwm_imx1_chip(chip) container_of(chip, struct pwm_imx1_chip, chip) + +static int pwm_imx1_clk_prepare_enable(struct pwm_chip *chip) +{ + struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip); + int ret; + + ret = clk_prepare_enable(imx->clk_ipg); + if (ret) + return ret; + + ret = clk_prepare_enable(imx->clk_per); + if (ret) { + clk_disable_unprepare(imx->clk_ipg); + return ret; + } + + return 0; +} + +static void pwm_imx1_clk_disable_unprepare(struct pwm_chip *chip) +{ + struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip); + + clk_disable_unprepare(imx->clk_per); + clk_disable_unprepare(imx->clk_ipg); +} + +static int pwm_imx1_config(struct pwm_chip *chip, + struct pwm_device *pwm, u64 duty_ns, u64 period_ns) +{ + struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip); + u32 max, p; + + /* + * The PWM subsystem allows for exact frequencies. However, + * I cannot connect a scope on my device to the PWM line and + * thus cannot provide the program the PWM controller + * exactly. Instead, I'm relying on the fact that the + * Bootloader (u-boot or WinCE+haret) has programmed the PWM + * function group already. So I'll just modify the PWM sample + * register to follow the ratio of duty_ns vs. period_ns + * accordingly. + * + * This is good enough for programming the brightness of + * the LCD backlight. + * + * The real implementation would divide PERCLK[0] first by + * both the prescaler (/1 .. /128) and then by CLKSEL + * (/2 .. /16). + */ + max = readl(imx->mmio_base + MX1_PWMP); + p = mul_u64_u64_div_u64(max, duty_ns, period_ns); + + writel(max - p, imx->mmio_base + MX1_PWMS); + + return 0; +} + +static int pwm_imx1_enable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip); + u32 value; + int ret; + + ret = pwm_imx1_clk_prepare_enable(chip); + if (ret < 0) + return ret; + + value = readl(imx->mmio_base + MX1_PWMC); + value |= MX1_PWMC_EN; + writel(value, imx->mmio_base + MX1_PWMC); + + return 0; +} + +static void pwm_imx1_disable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip); + u32 value; + + value = readl(imx->mmio_base + MX1_PWMC); + value &= ~MX1_PWMC_EN; + writel(value, imx->mmio_base + MX1_PWMC); + + pwm_imx1_clk_disable_unprepare(chip); +} + +static int pwm_imx1_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) + pwm_imx1_disable(chip, pwm); + + return 0; + } + + err = pwm_imx1_config(chip, pwm, state->duty_cycle, state->period); + if (err) + return err; + + if (!pwm->state.enabled) + return pwm_imx1_enable(chip, pwm); + + return 0; +} + +static const struct pwm_ops pwm_imx1_ops = { + .apply = pwm_imx1_apply, + .owner = THIS_MODULE, +}; + +static const struct of_device_id pwm_imx1_dt_ids[] = { + { .compatible = "fsl,imx1-pwm", }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, pwm_imx1_dt_ids); + +static int pwm_imx1_probe(struct platform_device *pdev) +{ + struct pwm_imx1_chip *imx; + + imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL); + if (!imx) + return -ENOMEM; + + imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg"); + if (IS_ERR(imx->clk_ipg)) + return dev_err_probe(&pdev->dev, PTR_ERR(imx->clk_ipg), + "getting ipg clock failed\n"); + + imx->clk_per = devm_clk_get(&pdev->dev, "per"); + if (IS_ERR(imx->clk_per)) + return dev_err_probe(&pdev->dev, PTR_ERR(imx->clk_per), + "failed to get peripheral clock\n"); + + imx->chip.ops = &pwm_imx1_ops; + imx->chip.dev = &pdev->dev; + imx->chip.npwm = 1; + + imx->mmio_base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(imx->mmio_base)) + return PTR_ERR(imx->mmio_base); + + return devm_pwmchip_add(&pdev->dev, &imx->chip); +} + +static struct platform_driver pwm_imx1_driver = { + .driver = { + .name = "pwm-imx1", + .of_match_table = pwm_imx1_dt_ids, + }, + .probe = pwm_imx1_probe, +}; +module_platform_driver(pwm_imx1_driver); + +MODULE_LICENSE("GPL v2"); +MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>"); |