[linux-block.git] / drivers / pwm / pwm-imx1.c

// 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>");
Commit	Line	Data
d80f8206 UKK	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* simple driver for PWM (Pulse Width Modulator) controller
	4	*
	5	* Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
	6	*/
	7
	8	#include <linux/bitfield.h>
	9	#include <linux/bitops.h>
	10	#include <linux/clk.h>
	11	#include <linux/delay.h>
	12	#include <linux/err.h>
	13	#include <linux/io.h>
	14	#include <linux/kernel.h>
	15	#include <linux/module.h>
	16	#include <linux/of.h>
	17	#include <linux/of_device.h>
	18	#include <linux/platform_device.h>
	19	#include <linux/pwm.h>
	20	#include <linux/slab.h>
	21
	22	#define MX1_PWMC 0x00 /* PWM Control Register */
	23	#define MX1_PWMS 0x04 /* PWM Sample Register */
	24	#define MX1_PWMP 0x08 /* PWM Period Register */
	25
	26	#define MX1_PWMC_EN BIT(4)
	27
	28	struct pwm_imx1_chip {
	29	struct clk *clk_ipg;
	30	struct clk *clk_per;
	31	void __iomem *mmio_base;
	32	struct pwm_chip chip;
	33	};
	34
	35	#define to_pwm_imx1_chip(chip) container_of(chip, struct pwm_imx1_chip, chip)
	36
	37	static int pwm_imx1_clk_prepare_enable(struct pwm_chip *chip)
	38	{
	39	struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
	40	int ret;
	41
	42	ret = clk_prepare_enable(imx->clk_ipg);
	43	if (ret)
	44	return ret;
	45
	46	ret = clk_prepare_enable(imx->clk_per);
	47	if (ret) {
	48	clk_disable_unprepare(imx->clk_ipg);
	49	return ret;
	50	}
	51
	52	return 0;
	53	}
	54
	55	static void pwm_imx1_clk_disable_unprepare(struct pwm_chip *chip)
	56	{
	57	struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
	58
	59	clk_disable_unprepare(imx->clk_per);
	60	clk_disable_unprepare(imx->clk_ipg);
	61	}
	62
	63	static int pwm_imx1_config(struct pwm_chip *chip,
b23fd25e	64	struct pwm_device *pwm, u64 duty_ns, u64 period_ns)
d80f8206 UKK	65	{
	66	struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
	67	u32 max, p;
	68
	69	/*
	70	* The PWM subsystem allows for exact frequencies. However,
	71	* I cannot connect a scope on my device to the PWM line and
	72	* thus cannot provide the program the PWM controller
	73	* exactly. Instead, I'm relying on the fact that the
	74	* Bootloader (u-boot or WinCE+haret) has programmed the PWM
	75	* function group already. So I'll just modify the PWM sample
	76	* register to follow the ratio of duty_ns vs. period_ns
	77	* accordingly.
	78	*
	79	* This is good enough for programming the brightness of
	80	* the LCD backlight.
	81	*
	82	* The real implementation would divide PERCLK[0] first by
	83	* both the prescaler (/1 .. /128) and then by CLKSEL
	84	* (/2 .. /16).
	85	*/
	86	max = readl(imx->mmio_base + MX1_PWMP);
b23fd25e	87	p = mul_u64_u64_div_u64(max, duty_ns, period_ns);
d80f8206 UKK	88
	89	writel(max - p, imx->mmio_base + MX1_PWMS);
	90
	91	return 0;
	92	}
	93
	94	static int pwm_imx1_enable(struct pwm_chip chip, struct pwm_device pwm)
	95	{
	96	struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
	97	u32 value;
	98	int ret;
	99
	100	ret = pwm_imx1_clk_prepare_enable(chip);
	101	if (ret < 0)
	102	return ret;
	103
	104	value = readl(imx->mmio_base + MX1_PWMC);
	105	value \|= MX1_PWMC_EN;
	106	writel(value, imx->mmio_base + MX1_PWMC);
	107
	108	return 0;
	109	}
	110
	111	static void pwm_imx1_disable(struct pwm_chip chip, struct pwm_device pwm)
	112	{
	113	struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
	114	u32 value;
	115
	116	value = readl(imx->mmio_base + MX1_PWMC);
	117	value &= ~MX1_PWMC_EN;
	118	writel(value, imx->mmio_base + MX1_PWMC);
	119
	120	pwm_imx1_clk_disable_unprepare(chip);
	121	}
	122
b23fd25e UKK	123	static int pwm_imx1_apply(struct pwm_chip chip, struct pwm_device pwm,
	124	const struct pwm_state *state)
	125	{
	126	int err;
	127
	128	if (state->polarity != PWM_POLARITY_NORMAL)
	129	return -EINVAL;
	130
	131	if (!state->enabled) {
	132	if (pwm->state.enabled)
	133	pwm_imx1_disable(chip, pwm);
	134
	135	return 0;
	136	}
	137
	138	err = pwm_imx1_config(chip, pwm, state->duty_cycle, state->period);
	139	if (err)
	140	return err;
	141
	142	if (!pwm->state.enabled)
	143	return pwm_imx1_enable(chip, pwm);
	144
	145	return 0;
	146	}
	147
d80f8206	148	static const struct pwm_ops pwm_imx1_ops = {
b23fd25e	149	.apply = pwm_imx1_apply,
d80f8206 UKK	150	.owner = THIS_MODULE,
	151	};
	152
	153	static const struct of_device_id pwm_imx1_dt_ids[] = {
	154	{ .compatible = "fsl,imx1-pwm", },
	155	{ /* sentinel */ }
	156	};
	157	MODULE_DEVICE_TABLE(of, pwm_imx1_dt_ids);
	158
	159	static int pwm_imx1_probe(struct platform_device *pdev)
	160	{
	161	struct pwm_imx1_chip *imx;
d80f8206 UKK	162
	163	imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
	164	if (!imx)
	165	return -ENOMEM;
	166
d80f8206	167	imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
f1332e92 AH	168	if (IS_ERR(imx->clk_ipg))
	169	return dev_err_probe(&pdev->dev, PTR_ERR(imx->clk_ipg),
	170	"getting ipg clock failed\n");
d80f8206 UKK	171
d80f8206 UKK	172	imx->clk_per = devm_clk_get(&pdev->dev, "per");
f1332e92 AH	173	if (IS_ERR(imx->clk_per))
	174	return dev_err_probe(&pdev->dev, PTR_ERR(imx->clk_per),
	175	"failed to get peripheral clock\n");
d80f8206 UKK	176
	177	imx->chip.ops = &pwm_imx1_ops;
	178	imx->chip.dev = &pdev->dev;
d80f8206 UKK	179	imx->chip.npwm = 1;
d80f8206 UKK	180
860b1ca0	181	imx->mmio_base = devm_platform_ioremap_resource(pdev, 0);
d80f8206 UKK	182	if (IS_ERR(imx->mmio_base))
	183	return PTR_ERR(imx->mmio_base);
	184
f7edeb40	185	return devm_pwmchip_add(&pdev->dev, &imx->chip);
d80f8206 UKK	186	}
	187
	188	static struct platform_driver pwm_imx1_driver = {
	189	.driver = {
	190	.name = "pwm-imx1",
	191	.of_match_table = pwm_imx1_dt_ids,
	192	},
	193	.probe = pwm_imx1_probe,
d80f8206 UKK	194	};
	195	module_platform_driver(pwm_imx1_driver);
	196
	197	MODULE_LICENSE("GPL v2");
	198	MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");