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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;
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>");
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