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