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- // 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, int duty_ns, int 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 = 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 const struct pwm_ops pwm_imx1_ops = {
- .enable = pwm_imx1_enable,
- .disable = pwm_imx1_disable,
- .config = pwm_imx1_config,
- .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;
- struct resource *r;
- imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
- if (!imx)
- return -ENOMEM;
- platform_set_drvdata(pdev, imx);
- imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
- if (IS_ERR(imx->clk_ipg)) {
- dev_err(&pdev->dev, "getting ipg clock failed with %ld\n",
- PTR_ERR(imx->clk_ipg));
- return PTR_ERR(imx->clk_ipg);
- }
- imx->clk_per = devm_clk_get(&pdev->dev, "per");
- if (IS_ERR(imx->clk_per)) {
- int ret = PTR_ERR(imx->clk_per);
- if (ret != -EPROBE_DEFER)
- dev_err(&pdev->dev,
- "failed to get peripheral clock: %d\n",
- ret);
- return ret;
- }
- imx->chip.ops = &pwm_imx1_ops;
- imx->chip.dev = &pdev->dev;
- imx->chip.base = -1;
- imx->chip.npwm = 1;
- r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
- imx->mmio_base = devm_ioremap_resource(&pdev->dev, r);
- if (IS_ERR(imx->mmio_base))
- return PTR_ERR(imx->mmio_base);
- return pwmchip_add(&imx->chip);
- }
- static int pwm_imx1_remove(struct platform_device *pdev)
- {
- struct pwm_imx1_chip *imx = platform_get_drvdata(pdev);
- return pwmchip_remove(&imx->chip);
- }
- static struct platform_driver pwm_imx1_driver = {
- .driver = {
- .name = "pwm-imx1",
- .of_match_table = pwm_imx1_dt_ids,
- },
- .probe = pwm_imx1_probe,
- .remove = pwm_imx1_remove,
- };
- module_platform_driver(pwm_imx1_driver);
- MODULE_LICENSE("GPL v2");
- MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
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